Podcasts about Hsp70

Demencja to jedno z największych wyzwań zdrowotnych naszych czasów. Szacuje się, że w 2019 roku na świecie żyło 57 milionów osób dotkniętych tą chorobą, a według prognoz do 2050 roku liczba ta wzrośnie do 153 milionów. Wzrost długości życia sprawia, że liczba przypadków stale rośnie, zwłaszcza w krajach o niższych dochodach. Czy można temu zapobiec? Jakie czynniki zwiększają ryzyko demencji i czy geny mają znaczenie? Jak dieta, ruch i sen wpływają na zdrowie mózgu? Na te i inne pytania odpowiemy w dzisiejszym odcinku.Moim dzisiejszym gościem jest Asia Wojsiat - neurobiolog i doktor nauk biologicznych w dyscyplinie biochemia (ze specjalnością neurochemia). Jej praca doktorska dotyczyła mechanizmów molekularnych powstawania choroby Alzheimera. Asia prowadzi swój autorski podcast „Wojsiat ogólnie”, jest autorem popularnonaukowej książki „Tak działa mózg. Jak mądrze zadbać o jego funkcjonowanie” oraz oraz filmu dokumentalnego "Jak ruchem zmieniać umysł" stworzonego wespół z fundacją Veritas. W swoich działaniach edukatorskich porusza głównie kwestie związane z neuronauką, neurobiologią, pracą z umysłem i medycyną stylu życia. Asię znajdziecie na Instagramie pod nickiem @drjoanwojsiat oraz stronie internetowej: https://drasiawojsiat.pl/ Odcinek podcastu jest wspierany przez markę Kogen, która czerpie inspirację z japońskiej filozofii troski o zdrowie oraz łączy naturę z osiągnięciami nauki. Marka Kogen tworzy zaawansowane nutraceutyki, które skutecznie wspierają organizm w radzeniu sobie z wyzwaniami współczesnego życia. Z kodem DRKARABIN otrzymasz 10% zniżki na produkty w sklepie Kogen: https://kogen.pl/sklep/Lista publikacji o których wspominamy w podcaście: https://docs.google.com/document/d/1sZJzFXBprS09y1ZLcpNT4DtzcknrVsISmokTdYSTacM/edit?usp=sharing Ten materiał nie stanowi zamiennika wizyty lekarskiej. Nie jest też poradą zdrowotną, ani nie służy do diagnozowania ani leczenia chorób. Materiał ma charakter wyłącznie edukacyjny. Autorka nie ponosi odpowiedzialności za sposób wykorzystania przedstawionych informacji.0:00 Intro 0:37 - Wstęp2:14 - Przedstawienie gościa4:10 - Czym jest demencja, jakie są jej rodzaje i jak często występuje?11:28 - Czy choroba Parkinsona jest rodzajem demencji?13:42 - Dlaczego schizofrenia czasami nazywana jest demencją młodych ludzi?16:33 - Jakie są najczęstsze objawy demencji?19:16 - Książki dotycząca demencji23:01 - Czy demencja jest dziedziczna?31:35 - W jaki sposób dieta może wpływać na ryzyko demencji?37:03 -  Alkohol a ryzyko demencji38:53 - Aktywność fizyczna a ryzyko demencji46:36 - Zanieczyszczenie środowiska a ryzyko demencji47:45 - Aktywność intelektualna - czym jest i w jaki sposób może zmniejszać ryzyko demencji50:38 - Samotność i izolacja społeczna  a ryzyko demencji56:15 - W jaki sposób zapobiegać demencji?57:45 - Sen a ryzyko demencji1:02:20 - Co powoduje choroby neurodegeneracyjne?1:09:18 - Jakie są metody leczenia farmakologicznego  choroby Alzheimera?1:11:39 -  Czym jest białko HSP70 i jaki ma związek z demencją?1:18:04 - Podsumowanie - czy da się spowolnić postępowanie chorób neurodegeneracyjnych?

Drs. Mehdi Mollapour, Jennifer Heritz, and Sarah Backe from SUNY Upstate Medical University (Syracuse, NY) discuss a review they co-authored that was published by Oncotarget in Volume 15, entitled, “Molecular chaperones: Guardians of tumor suppressor stability and function.” DOI - https://doi.org/10.18632/oncotarget.28653 Correspondence to - Mehdi Mollapour - mollapom@upstate.edu Video interview - https://www.youtube.com/watch?v=vEHmyemWgNo Video transcript - https://www.oncotarget.net/2024/10/24/behind-the-study-molecular-chaperones-tumor-suppressor-stability/ Abstract The term ‘tumor suppressor' describes a widely diverse set of genes that are generally involved in the suppression of metastasis, but lead to tumorigenesis upon loss-of-function mutations. Despite the protein products of tumor suppressors exhibiting drastically different structures and functions, many share a common regulatory mechanism—they are molecular chaperone ‘clients'. Clients of molecular chaperones depend on an intracellular network of chaperones and co-chaperones to maintain stability. Mutations of tumor suppressors that disrupt proper chaperoning prevent the cell from maintaining sufficient protein levels for physiological function. This review discusses the role of the molecular chaperones Hsp70 and Hsp90 in maintaining the stability and functional integrity of tumor suppressors. The contribution of cochaperones prefoldin, HOP, Aha1, p23, FNIP1/2 and Tsc1 as well as the chaperonin TRiC to tumor suppressor stability is also discussed. Genes implicated in renal cell carcinoma development—VHL, TSC1/2, and FLCN—will be used as examples to explore this concept, as well as how pathogenic mutations of tumor suppressors cause disease by disrupting protein chaperoning, maturation, and function. Sign up for free Altmetric alerts about this article: https://oncotarget.altmetric.com/details/email_updates?id=10.18632%2Foncotarget.28653 Subscribe for free publication alerts from Oncotarget: https://www.oncotarget.com/subscribe/ Keywords - cancer, molecular chaperone, tumor suppressor, renal cell carcinoma, Birt-Hogg-Dubé (BHD) syndrome, TSC syndrome About Oncotarget Oncotarget (a primarily oncology-focused, peer-reviewed, open access journal) aims to maximize research impact through insightful peer-review; eliminate borders between specialties by linking different fields of oncology, cancer research and biomedical sciences; and foster application of basic and clinical science. Oncotarget is indexed and archived by PubMed/Medline, PubMed Central, Scopus, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science). To learn more about Oncotarget, please visit https://www.oncotarget.com and connect with us: Facebook - https://www.facebook.com/Oncotarget/ X - https://twitter.com/oncotarget Instagram - https://www.instagram.com/oncotargetjrnl/ YouTube - https://www.youtube.com/@OncotargetJournal LinkedIn - https://www.linkedin.com/company/oncotarget Pinterest - https://www.pinterest.com/oncotarget/ Reddit - https://www.reddit.com/user/Oncotarget/ Spotify - https://open.spotify.com/show/0gRwT6BqYWJzxzmjPJwtVh MEDIA@IMPACTJOURNALS.COM

BUFFALO, NY- October 16, 2024 – A new #review was #published in Oncotarget's Volume 15 on October 1, 2024, entitled, “Molecular chaperones: Guardians of tumor suppressor stability and function.” As highlighted in the abstract of this paper, "tumor suppressor" describes a diverse set of genes typically involved in suppressing metastasis, but which can lead to tumorigenesis when loss-of-function mutations occur. Despite the varied structures and functions of tumor suppressor proteins, many share a common regulatory mechanism—they are "clients" of molecular chaperones, and they rely on an intracellular network of chaperones and co-chaperones to maintain their stability. Mutations in tumor suppressors that disrupt proper chaperoning prevent cells from maintaining sufficient protein levels for normal physiological function. In their review, researchers Jennifer A. Heritz, Sarah J. Backe, and Mehdi Mollapour from SUNY Upstate Medical University and New York VA Health Care in Syracuse, New York, discuss the role of molecular chaperones Hsp70 and Hsp90 in maintaining the stability and functional integrity of tumor suppressors. They also detail the contributions of co-chaperones prefoldin, HOP, Aha1, p23, FNIP1/2, and Tsc1, as well as the chaperonin TRiC, to tumor suppressor stability. “Overall, it is clear that oncogenesis can result from the dysregulation of tumor suppressor stabilization by chaperones.” DOI - https://doi.org/10.18632/oncotarget.28653 Correspondence to - Mehdi Mollapour - mollapom@upstate.edu Video short - https://www.youtube.com/watch?v=V5OFjeqaH3A Sign up for free Altmetric alerts about this article: https://oncotarget.altmetric.com/details/email_updates?id=10.18632%2Foncotarget.28653 Subscribe for free publication alerts from Oncotarget: https://www.oncotarget.com/subscribe/ Keywords - cancer, molecular chaperone, tumor suppressor, renal cell carcinoma, Birt-Hogg-Dubé (BHD) syndrome, TSC syndrome About Oncotarget Oncotarget (a primarily oncology-focused, peer-reviewed, open access journal) aims to maximize research impact through insightful peer-review; eliminate borders between specialties by linking different fields of oncology, cancer research and biomedical sciences; and foster application of basic and clinical science. Oncotarget is indexed and archived by PubMed/Medline, PubMed Central, Scopus, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science). To learn more about Oncotarget, please visit https://www.oncotarget.com and connect with us: Facebook - https://www.facebook.com/Oncotarget/ X - https://twitter.com/oncotarget Instagram - https://www.instagram.com/oncotargetjrnl/ YouTube - https://www.youtube.com/@OncotargetJournal LinkedIn - https://www.linkedin.com/company/oncotarget Pinterest - https://www.pinterest.com/oncotarget/ Reddit - https://www.reddit.com/user/Oncotarget/ Spotify - https://open.spotify.com/show/0gRwT6BqYWJzxzmjPJwtVh MEDIA@IMPACTJOURNALS.COM

In Episode 9 of the Athletes Compass podcast, hosts Paul Warloski and Marjaana Rakai, along with Dr. Paul Laursen, discuss the short-term and potential long-term effects of extreme endurance events on the body, addressing a question from listener Janice Campbell. The episode delves into various stressors athletes face during such events and the time frame for recovery.Key Discussion Points:Short-term Effects of Extreme Endurance Events:Gastrointestinal Issues: Often occur, especially during running in triathlons, and can be nutritional or related to sugar intake.Electrolyte Imbalance: Conditions like hypernatremia due to excessive water intake or significant sweat loss.Temperature-Related Issues: Heatstroke or hypothermia, depending on the event's environmental conditions.Muscle Damage and Inflammation: Caused by microtears during long runs or events like Ironman, leading to substances like myoglobin present in the blood, potentially causing rhabdomyolysis.Central Nervous System Fatigue: A feeling of being utterly drained after an event.Recovery from Extreme Events:The recovery process involves a gradual decrease in markers of muscle damage (like creatine kinase and myoglobin) over a period of days.Recovery methods and strategies, including the importance of hydration and monitoring sodium levels to prevent conditions like hyponatremia.The role of proper nutrition and rest in the recovery process.Potential Long-term Effects:Discussion on the rarity but existence of long-term health effects like heart issues, with examples from professional athletes.Importance of considering lifestyle factors, overall stress, and nutrition in relation to long-term health.The balance between the benefits of exercise and potential risks, emphasizing quality of life and a common-sense approach to training and health monitoring.Self-Monitoring and Awareness:The importance of being attentive to abnormal symptoms or changes in performance, which may indicate more significant health issues.The role of common sense and tools like heart rate monitoring, pace, power, and heart rate variability in understanding one's health and training status.Changes in markers of muscle damage, inflammation and HSP70 after an Ironman Triathlon race - PubMedThe Coaching Professor — Dangerous Waters: The Hidden Threat of HyponatremiaCore temperature and hydration status during an Ironman Core temperature and hydration status during an Ironman triathlon triathlon Muscle damage and inflammation during recovery from exercise - Kazunori "Ken" NosakaMaximum Aerobic Function: Clinical Relevance, Physiological Underpinnings, and Practical ApplicationPaul Warloski - Endurance, Strength Training, YogaMarjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.Athletica AI Endurance Training Platform

The life of a protein, from birth till death, is complex and challenging. At times, because of stresses or bad luck, it might take the wrong conformation and start aggregating. This process is intrinsic to the physics of proteins, and life has had to cope with it since its early days. The solution devised by evolution comes in the form of chaperone protein, a broad class of machines, present in all organisms on Earth, that repair conformationally damaged proteins, making them functional again, at an energy cost. In this talk I will provide a view of our present understanding of the molecular mechanism of function of Hsp70, possibly the most central of all chaperones, and of its consequences on proteins.

The third in a series about the beneficial effects of Ashwagandha, this episode looks at the anti-stress and adaptogenic effects of this incredible herb. Ashwagandha helps improve neuronal plasticity and regeneration, and reduces the damage and death of these cells. To accomplish this effect, ashwagandha triggers the upregulation of HSP70 proteins. Let's review. URL list from August 3, 2023 Pharmaceutics | Free Full-Text | Ashwagandha (Withania somnifera)—Current Research on the Health-Promoting Activities: A Narrative Review https://www.mdpi.com/1999-4923/15/4/1057 Evidence-Based Efficacy of Adaptogens in Fatigue, and Molecular M...: Ingenta Connect https://www.ingentaconnect.com/content/ben/ccp/2009/00000004/00000003/art00004 Heat Shock Protein 70 (Hsp70) as an Emerging Drug Target - PMC https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2895966/#:~:text=Heat%20shock%20protein%2070%20(Hsp70)%20is%20a%20molecular%20chaperone%20that,or%20aggregation%20until%20conditions%20improve . Adaptogenic activity of Withania somnifera: an experimental study using a rat model of chronic stress - ScienceDirect https://www.sciencedirect.com/science/article/abs/pii/S0091305703001102 Phytotherapy Research | Medicinal Chemistry Journal | Wiley Online Library https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.858 Frontiers | c-Jun N-terminal Kinase (JNK) Signaling as a Therapeutic Target for Alzheimer's Disease https://www.frontiersin.org/articles/10.3389/fphar.2015.00321/full Frontiers | DAF-16/FOXO Transcription Factor in Aging and Longevity https://www.frontiersin.org/articles/10.3389/fphar.2017.00548/full Disclaimer: This video is not intended to provide assessment, diagnosis, treatment, or medical advice; it also does not constitute provision of healthcare services. The content provided in this video is for informational and educational purposes only. Please consult with a physician or healthcare professional regarding any medical or mental health related diagnosis or treatment. No information in this video should ever be considered as a substitute for advice from a healthcare professional.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.03.547488v1?rss=1 Authors: Romenskaja, D., Jonavice, U., Pivoriunas, A. Abstract: Autophagy dysfunction has been closely related with pathogenesis of many neurodegenerative diseases and therefore represents a potential therapeutic target. Extracellular vesicles (EVs) may act as a potent anti-inflammatory agents and also modulators of autophagy in target cells. However, the molecular mechanisms by which EVs modulate autophagy flux in human microglia remain largely unexplored. In the present study we investigated the effects of EVs derived from human oral mucosa stem cells on the autophagy in human microglia. We demonstrate that EVs promoted autophagy and autophagic flux in human microglia and that this process was dependent on the integrity of lipid rafts. LPS also activated autophagy, but combined treatment with EVs and LPS suppressed autophagy response indicating interference between these signalling pathways. Blockage of Toll-like receptor 4 (TLR4) with anti-TLR4 antibody suppressed EV-induced autophagy. Furthermore, blockage of EV- asscoiated HSP70 chaperone which is one of the endogenous ligands of the TLR4 also suppressed EV- induced lipid raft formation and autophagy. Pre-treatment of microglia with selective inhibitor of v{beta}3/v{beta}5 integrins cilengitide inhibited EV-induced autophagy. Finally, blockage of purinergic P2X4 receptor (P2X4R) with selective inhibitor 5-BDBD also suppressed of EV-induced autophagy. In conclusion, we demonstrate that EVs activate autophagy in human microglia through interaction with HSP70/TLR4, V{beta}3/V{beta}5, and P2X4R signalling pathways and that these effects depend on the integrity of lipid rafts. Our findings could be used for development of new therapeutic strategies targeting disease-associated microglia. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.04.01.535233v1?rss=1 Authors: Zhang, P.-P., Benske, T. M., Paton, J. C., Paton, A. W., Mu, T., Wang, Y.-J. Abstract: The GRIN genes encoding N-methyl-D-aspartate receptor (NMDAR) subunits are remarkably intolerant to variation. Many pathogenic NMDAR variants result in their protein misfolding, inefficient assembly, reduced surface expression, and impaired functionality at the plasma membrane, causing neurological disorders including epilepsy and intellectual disability. Here, we concentrate on the proteostasis maintenance of NMDARs containing epilepsy-associated variations in the GluN2A (or NR2A) subunit, including M705V and A727T. We showed that these two variants are targeted to the proteasome for degradation and have reduced functional surface expression. We demonstrated that the application of BIX, a known small molecule activator of an HSP70 family chaperone BiP (Binding immunoglobulin Protein) in the endoplasmic reticulum (ER), significantly increases total and surface protein levels, and thus the function of the M705V and A727T variants in HEK293T cells. Mechanistic studies revealed that BIX promotes folding, inhibits degradation, and enhances anterograde trafficking of the M705V variant by modest activation of the IRE1 pathway of the unfolded protein response. Our results showed that adapting the ER proteostasis network restores the folding, trafficking, and function of pathogenic NMDAR variants, representing a potential treatment for neurological disorders resulting from NMDAR dysfunction. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.22.529417v1?rss=1 Authors: Hino, C., Chan, G., Jordaan, G., Chang, S. S., Saunders, J., Bashir, M. T., Hansen, J. E., Gera, J., Weisbart, R. H., Nishimura, R. N. Abstract: Heat shock proteins (HSPs), especially Hsp70 (HSPA1), have been associated with cellular protection from various cellular stresses including heat, hypoxia-ischemia, neurodegeneration, toxins, and trauma. Endogenous HSPs are often synthesized in direct response to these stresses but in many situations are inadequate in protecting cells. The present study addresses the transduction of Hsp70 into cells providing protection from acute oxidative stress by H2O2. The recombinant Fv-Hsp70 protein and two mutant Fv-Hsp70 proteins minus the ATPase domain, and minus the ATPase and terminal lid domains were tested at 0.5 and 1.0 uM concentrations after two different concentrations of H2O2 treatment. All three recombinant proteins protected SH-SY5Y cells from acute H2O2 toxicity. This data indicated that the protein binding domain was responsible for cellular protection. In addition, experiments pretreating cells with inhibitors of antioxidant proteins catalase and gamma-glutamylcysteine synthase (GGCS) before H2O2 resulted in cell death despite treatment with Fv-Hsp70, implying that both enzymes were protected from acute oxidative stress after treatment with Fv-Hsp70. This study demonstrates that Fv-Hsp70 is protective in our experiments primarily by the protein-binding domain. The Hsp70 terminal lid domain was also not necessary for protection. Cellular protection was protective via the antioxidant proteins catalase and GGCS. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.17.528950v1?rss=1 Authors: Gayen, N., Mitra, S., Roy, S., Mandal, A. K. Abstract: The stability and activity of CRAF kinase are stringently regulated by heat shock protein 90 (Hsp90). Hsp90-mediated client folding and maturation is governed by its co-chaperones, but their functionality in chaperoning CRAF/Raf1 kinase to accomplish signaling under physiological conditions remains poorly understood. Here, we show that Hsp70/Hsp90 organizing protein (HOP) associates with CRAF kinase for maintaining its kinase activity and facilitates the activation of the MAPK pathway. Such activation is mediated by TPR2A-2B-DP2 domain of HOP and requires efficient binding to Hsp90. Being a recruiter of Hsp90, Cdc37 is unable to supplement the function of HOP/Sti1. Downregulation of HOP/Sti1 in yeast and in vitro cell culture significantly reduces the CRAF signaling. Our data suggest that Hsp90 is recruited to CRAF in two steps, separately initiated by co-chaperones HOP and Cdc37 respectively during CRAF folding/maturation, and again upon CRAF activation mediated by HOP during MAPK signaling. Therefore, HOP is a regulator of CRAF kinase during activation of MAPK pathway and serves as a sensor of growth signaling beyond its client folding and maturation function. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.02.526918v1?rss=1 Authors: Singh, G., Lakhotia, S. C. Abstract: Oncogenic cells recruit diverse cellular survival machineries, including the highly conserved heat shock proteins (Hsps), to counter stressful conditions during tumour progression. Despite important roles of Hsps in several cancers, poor understanding of their regulation leaves major gaps in identifying mechanisms of cellular stress responses exploited by cancer cells. Following our earlier report of stress inducible Hsp70 expression only in a few cells in polarity defective tumorous clones, we now show that Hsp70 is expressed only in neoplastic tumours. Hsp70s expression at 72h after clone induction is mostly limited to a few lgl- ykiOE cells exhibiting mesenchymal features in hypoxic zone closer to tracheae, although all tumorous cells express hsp70 transcripts. Down-regulation of the hsp70a but not hsp70b cluster transcripts substantially suppresses growth of lgl- ykiOE clones without affecting their early establishment. However, over-expression of Hsp70 or Hsp70-cochaperone DnaJ suppress lgl- ykiOE clones growth at early stage. This spatially and temporally regulated expression of Hsp70 in lgl- ykiOE clones is independent of HSF but requires dFOXO and JNK signalling, while a nearly similar pattern of Hsp70 expression in lgl- RasV12 clones requires HSF, rather than dFOXO. Such context dependent Hsp70 regulation provides novel insight into stress regulatory machinery in cancer cells. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.11.09.515856v1?rss=1 Authors: Ali, A., Garde, R., Schaffer, O. C., Bard, J. A. M., Husain, K., Keyport Kik, S., Davis, K. A., Luengo-Woods, S., Drummond, D. A., Squires, A. H., Pincus, D. Abstract: Ribosome biogenesis is among the most resource-intensive cellular processes, with ribosomal proteins accounting for up to half of all newly synthesized proteins in eukaryotic cells. During stress, cells shut down ribosome biogenesis in part by halting rRNA synthesis, potentially leading to massive accumulation of aggregation-prone 'orphan' ribosomal proteins (oRPs). Here we show that during heat shock in yeast and human cells, oRPs accumulate as reversible condensates at the nucleolar periphery recognized by the Hsp70 co-chaperone Sis1/DnaJB6. oRP condensates are liquid-like in cell-free lysate but solidify upon depletion of Sis1 or inhibition of Hsp70. When cells recover from heat shock, oRP condensates disperse in a Sis1-dependent manner, and their ribosomal protein constituents are incorporated into functional ribosomes in the cytosol, enabling cells to efficiently resume growth. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.11.01.514535v1?rss=1 Authors: Lavie, J., Lalou, C., Mahouf, W., Dupuy, J.-W., Lacaule, A., Ars, A., Lacombe, D., Duchene, A.-M., Raymond, A.-A., Rezvani, H. R., Ngondo, P., Benard, G. Abstract: The large majority of mitochondrial proteins is synthesized in the cytosol and then imported to the organelle. To ensure proper mitochondrial functions, the quality of these proteins needs to be guaranteed. Here, we show that the E3 ubiquitin ligase F-box/LRR-repeat protein 6 (FBXL6) participates to the quality of these mitochondrial proteins at the level of the cytosolic translation. We found that lack of FBXL6 has severe effects including mitochondrial ribosomal protein aggregations, altered mitochondrial metabolism and inhibited cell cycle progression in oxidative conditions. FBXL6 was found to interact specifically with ribosomal-associated quality control proteins and chaperones involved in the regulation of newly synthesized proteins and also it preferentially binds newly synthesized mitochondrial ribosomal proteins. Consistently, deletion of the RQC protein, NEMF or HSP70-family chaperone HSPA1A impedes FBXL6 interaction with its substrate. In addition, cells lacking FBXL6 display altered degradation of defective mitochondrial ribosomal protein containing C-terminal alanyl-threonyl extension. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.10.16.512122v1?rss=1 Authors: Desai, M., Singh, H., Deo, A., Naik, J., Bose, T., Majumdar, A. Abstract: Orb2 the Drosophila homolog of Cytoplasmic polyadenylation element binding protein (CPEB) forms prion-like oligomers. These oligomers consist of Orb2A and Orb2B isoforms and their formation are dependent on the oligomerization of the Orb2A isoform. Drosophila with a mutation diminishing Orb2A's prion-like oligomerization forms long-term memory but fails to maintain it over time. Since, this prion-like oligomerization of Orb2A plays a crucial role in the maintenance of memory, here we aim to find what regulates this oligomerization. In an immunoprecipitation-based screen, we identify interactors of Orb2A in the Hsp40 and Hsp70 families of proteins. Amongst these, we find an Hsp40 family protein Mrj as a regulator of the conversion of Orb2A to its prion-like form. Mrj interacts with Hsp70 proteins and acts as a chaperone by interfering with the aggregation of pathogenic Huntingtin. Unlike its mammalian homolog, we find Drosophila Mrj is neither an essential gene nor causes any gross neurodevelopmental defect. We observe a loss of Mrj results in a reduction in Orb2 oligomers. Further, the knockdown of Mrj in the mushroom body neurons results in a deficit in long-term memory. Our work implicates a chaperone Mrj in mechanisms of memory regulation through controlling the oligomerization of Orb2A and its association with the translating polysomes. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

A new research paper was published in Aging (“Aging (Albany NY)” by Medline/PubMed, “Aging-US” by Web of Science) Volume 14, Issue 16, entitled, “Systemic lipolysis promotes physiological fitness in Drosophila melanogaster.” A large body of literature shows that lipid metabolism exerts profound regulatory effects on aging and affects stress responses. Interventions such as caloric restriction or fasting robustly promote lipid catabolism and improve aging-related phenotypical markers. Researchers Linshan Shang, Elizabeth Aughey, Huiseon Kim, Timothy D. Heden, Lu Wang, Charles P. Najt, Nicholas Esch, Sophia Brunko, Juan E. Abrahante, Marissa Macchietto, Mara T. Mashek, Todd Fairbanks, Daniel E. L. Promislow, Thomas P. Neufeld, and Douglas G. Mashek from the University of Minnesota and University of Washington investigated the direct effect of increased lipid catabolism via overexpression of bmm (brummer, FBgn0036449), the major triglyceride hydrolase in Drosophila, on lifespan and physiological fitness. Comprehensive characterization was carried out using RNA-seq, lipidomics and metabolomics analysis. Global overexpression of bmm strongly promoted numerous markers of physiological fitness, including increased female fecundity, fertility maintenance, preserved locomotion activity, increased mitochondrial biogenesis and oxidative metabolism. Since bmm drives fatty acid oxidation, the data in this study implicated differential partitioning of glucose into the pentose phosphate pathway and purine biosynthesis between males and females. However, the underlying mechanisms through which bmm elicits these sex-specific effects remains to be determined. “Increased bmm robustly upregulated the heat shock protein 70 (Hsp70) family of proteins, which equipped the flies with higher resistance to heat, cold, and ER [endoplasmic reticulum] stress via improved proteostasis.” Despite improved physiological fitness, bmm overexpression did not extend lifespan. Taken together, these data show that bmm overexpression has broad beneficial effects on physiological fitness, but not lifespan. “Collectively, these studies reveal diverse beneficial effects of global elevation of lipolysis on physiological fitness. This work provides additional rationale for pursuing therapeutic approaches, as done previously [39], that enhance lipolysis to mitigate metabolic and aging-related diseases.” DOI: https://doi.org/10.18632/aging.204251 Corresponding Author: Douglas G. Mashek – Email: dmashek@umn.edu Keywords: brummer, lipolysis, physiological fitness, stress resistance, proteostasis Sign up for free Altmetric alerts about this article: https://aging.altmetric.com/details/email_updates?id=10.18632%2Faging.204251 About Aging-US: Launched in 2009, Aging (Aging-US) publishes papers of general interest and biological significance in all fields of aging research and age-related diseases, including cancer—and now, with a special focus on COVID-19 vulnerability as an age-dependent syndrome. Topics in Aging go beyond traditional gerontology, including, but not limited to, cellular and molecular biology, human age-related diseases, pathology in model organisms, signal transduction pathways (e.g., p53, sirtuins, and PI-3K/AKT/mTOR, among others), and approaches to modulating these signaling pathways. Please visit our website at www.Aging-US.com​​ and connect with us: SoundCloud – https://soundcloud.com/Aging-Us Facebook – https://www.facebook.com/AgingUS/ Twitter – https://twitter.com/AgingJrnl Instagram – https://www.instagram.com/agingjrnl/ YouTube – https://www.youtube.com/agingus​ LinkedIn – https://www.linkedin.com/company/aging/ Reddit – https://www.reddit.com/user/AgingUS Pinterest – https://www.pinterest.com/AgingUS/ For media inquiries, please contact media@impactjournals.com

In this 40 min discussion Dr Viehweger explains the importance of heat shock or chaperone proteins in cellular protection - called the heat shock response (HSR). We see how these proteins protect three dimensional protein folding and therefore function when exposed to threat like viral infection or cancer for instance. In fact they were first discovered after cells were exposed to heat - hence the name - so are very important in instances of fever and other cellular threats. Proteins are the building blocks of life, being part of both the structure of membranes, organelles and even DNA transcription (reading) so without them our cells die pretty quickly.  Heat shock proteins are categorised by their molecular weight and there are very many of them. One of the most significant groups to be studied are the HSP70 group.  We have teamed up with other practitioners to form a virtual health group called Greenwood Holistic Health Group offering an integrated multidisciplinary approach to chronic fatigue and post-viral syndromes. (see fatigue-free.me - from March 2021)  We can be contacted on greenwoodholistic@gmail.com and individually at tybmas-health.co.uk (where the HSP drops can be ordered) and alchemytherapies.co.uk 

In this 40 min discussion Dr Viehweger explains the importance of heat shock or chaperone proteins in cellular protection - called the heat shock response (HSR). We see how these proteins protect three dimensional protein folding and therefore function when exposed to threat like viral infection or cancer for instance. In fact they were first discovered after cells were exposed to heat - hence the name - so are very important in instances of fever and other cellular threats. Proteins are the building blocks of life, being part of both the structure of membranes, organelles and even DNA transcription (reading) so without them our cells die pretty quickly.Heat shock proteins are categorised by their molecular weight and there are very many of them. One of the most significant groups to be studied are the HSP70 group.We have teamed up with other practitioners to form a virtual health group called Greenwood Holistic Health Group offering an integrated multidisciplinary approach to chronic fatigue and post-viral syndromes. (see fatigue-free.me - from March 2021)We can be contacted on greenwoodholistic@gmail.com and individually at tybmas-health.co.uk (where the HSP drops can be ordered) and alchemytherapies.co.uk

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.11.05.370247v1?rss=1 Authors: Wang, R. Y.- R., Noddings, C. M., Kirschke, E., Myasnikov, A., Johnson, J. L., Agard, D. A. Abstract: Maintaining a healthy proteome is fundamental for organism survival. Integral to this are Hsp90 and Hsp70 molecular chaperones that together facilitate the folding, remodeling and maturation of Hsp90's many "client" proteins. The glucocorticoid receptor (GR) is a model client strictly dependent upon Hsp90/Hsp70 for activity. Chaperoning GR involves a cycle of inactivation by Hsp70, formation of an inactive GR:Hsp90:Hsp70:Hop "loading" complex, conversion to an active GR:Hsp90:p23 "maturation" complex, and subsequent GR release. Unfortunately, a molecular understanding of this intricate chaperone cycle is lacking for any client. Here, we report the cryo-EM structure of the GR loading complex, in which Hsp70 loads GR onto Hsp90, revealing the molecular basis of direct Hsp90/Hsp70 coordination. The structure reveals two Hsp70s--one delivering GR and the other scaffolding Hop. Unexpectedly, the Hop cochaperone interacts with all components of the complex including GR, poising Hsp90 for subsequent ATP hydrolysis. GR is partially unfolded and recognized via an extended binding pocket composed of Hsp90, Hsp70 and Hop, revealing the mechanism of GR loading and inactivation. Together with the GR maturation complex (Noddings et al., 2020), we present the first complete molecular mechanism of chaperone-dependent client remodeling, establishing general principles of client recognition, inhibition, transfer and activation. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.11.02.365825v1?rss=1 Authors: Schneider, M. M., Gautam, S., Herling, T. W., Andrzejwska, E., Krainer, G., Miller, A. M., Peter, Q. A. E., Ruggeri, F. S., Vendruscolo, M., Bracher, A., Dobson, C. M., Hartl, F.-U., Knowles, T. Abstract: Molecular chaperones contribute to the maintenance of cellular protein homeostasis through a wide range of mechanisms, including the assistance of de novo protein folding, the rescue of misfolded proteins, and the prevention of amyloid formation. Chaperones of the Hsp70 family have a striking capability of disaggregating otherwise irreversible aggregate structures such as amyloid fibrils that accumulate during the development of neurodegenerative diseases. However, the mechanisms of this key emerging functionality remain largely unknown. Here, we bring together microfluidic measurements with kinetic analysis and show that that the Hsp70 protein heat chock complement Hsc70 together with its two co-chaperones DnaJB1 and the nucleotide exchange factor Apg2 is able to completely reverse the aggregation process of alpha-synuclein, associated with Parkinson's disease, back to its soluble monomeric state. Moreover, we show that this reaction proceeds with first order kinetics in a process where monomer units are taken off directly from the fibril ends. Our results demonstrate that all components of the chaperone triad are essential for fibril disaggregation. Lastly, we quantify the interactions between the three chaperones as well as between the chaperones and the fibrils in solution, yielding both binding stoichiometries and dissociation constants. Crucially, we find that the stoichiometry of Hsc70 binding to fibrils suggests Hsc70 clustering at the fibril ends. Taken together, our results show that the mechanism of action of the Hsc70-DnaJB1-Apg2 chaperone system in disaggregating -synuclein fibrils involves the removal of monomer units without any intermediate fragmentation steps. These findings are fundamental to our understanding of the suppression of amyloid proliferation early in life and the natural clearance mechanisms of fibrillar deposits in Parkinson's disease, and inform on the possibilities and limitations of this strategy in the development of therapeutics against synucleinopathies and related neurodegenerative diseases. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.24.311779v1?rss=1 Authors: Jin, Y., Kotler, J. L. M., Wang, S., Huang, B., Halpin, J. C., Street, T. O. Abstract: While cytosolic Hsp70 and Hsp90 chaperones have been extensively studied, less is known about how the ER Hsp70 and Hsp90 paralogs (BiP and Grp94) recognize clients and influence their folding. Here, we examine how BiP and Grp94 influence the folding of insulin-like growth factor 2 (IGF2). Full-length proIGF2 is composed of an insulin-like hormone and an E-peptide that has sequence characteristics of an intrinsically disordered region. We find that the E-peptide region allows proIGF2 to form oligomers. BiP and Grp94 influence both the folding and the oligomerization of proIGF2. BiP and Grp94 exert a similar holdase function on proIGF2 folding by preferentially binding the proIGF2 unfolded state, rather than stabilizing specific folding intermediates and changing the proIGF2 folding process. In contrast, BiP and Grp94 exert counteracting effects on proIGF2 oligomerization. BiP suppresses proIGF2 oligomerization under both ADP and ATP conditions. Interestingly, Grp94 can enhance proIGF2 oligomerization when Grp94 adopts an open conformation (ADP conditions), but not when Grp94 is in the closed conformation (ATP conditions). We propose that BiP and Grp94 regulate the assembly of proIGF2 oligomers, and that regulated oligomerization may enable proIGF2 to be effectively packaged for export from the ER to the Golgi. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.12.294975v1?rss=1 Authors: Noddings, C. M., Wang, R. Y.-R., Agard, D. A. Abstract: Hsp90 is a conserved and essential molecular chaperone responsible for the folding and activation of hundreds of client proteins. The glucocorticoid receptor (GR) is a model client that constantly depends on Hsp90 for activity. Previously, we revealed GR ligand binding is inhibited by Hsp70 and restored by Hsp90, aided by the cochaperone p23. However, a molecular understanding of the chaperone-induced transformations that occur between the inactive Hsp70:Hsp90 client-loading complex and an activated Hsp90:p23 client-maturation complex is lacking for GR, or for any client. Here, we present a 2.56A cryo-EM structure of the GR-maturation complex (GR:Hsp90:p23), revealing that the GR ligand binding domain is, surprisingly, restored to a folded, ligand-bound conformation, while simultaneously threaded through the Hsp90 lumen. Also, unexpectedly, p23 directly stabilizes native GR using a previously uncharacterized C-terminal helix, resulting in enhanced ligand-binding. This is the highest resolution Hsp90 structure to date and the first atomic resolution structure of a client bound to Hsp90 in a native conformation, sharply contrasting with the unfolded kinase:Hsp90 structure. Thus, aided by direct cochaperone:client interactions, Hsp90 dictates client-specific folding outcomes. Together with the GR-loading complex structure (Wang et al. 2020), we present the molecular mechanism of chaperone-mediated GR remodeling, establishing the first complete chaperone cycle for any client. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.04.283028v1?rss=1 Authors: Gersing, S. K., Wang, Y., Gronbaek-Thygesen, M., Kampmeyer, C., Clausen, L., Andreasson, C., Stein, A., Lindorff-Larsen, K., Hartmann-Petersen, R. Abstract: Canavan disease is a severe progressive neurodegenerative disorder that is characterized by swelling and spongy degeneration of brain white matter. The disease is genetically linked to polymorphisms in the aspartoacylase (ASPA) gene, including the substitution C152W. ASPA C152W is associated with greatly reduced protein levels in cells, yet biophysical experiments suggest a wild-type like thermal stability. Here, we examine the stability and degradation pathway of ASPA C152W. When we expressed ASPA C152W in Saccharomyces cerevisiae, we found a decreased steady state compared to wild-type ASPA as a result of increased proteasomal degradation. However, molecular dynamics simulations of ASPA C152W did not substantially deviate from wild-type ASPA, indicating that the native state is structurally preserved. Instead, we suggest that the C152W substitution prevents ASPA from reaching its stable native conformation, presumably by impacting on de novo folding. Systematic mapping of the protein quality control components acting on misfolded and aggregation-prone species of C152W, revealed that the degradation is highly dependent on the molecular chaperone Hsp70, its co-chaperone Hsp110 as well as several quality control E3 ubiquitin-protein ligases, including Ubr1. In human cells, ASPA C152W displayed increased proteasomal turnover that was similarly dependent on Hsp70 and Hsp110. We propose that Hsp110 is a potential therapeutic target for misfolding ASPA variants that trigger Canavan disease due to excessive degradation. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.13.249201v1?rss=1 Authors: Moharir, S. C., Raghawan, A. K., Swarup, G. Abstract: Optineurin (OPTN), a cytoplasmic adaptor protein involved in cargo selective autophagy of bacteria, damaged mitochondria and mutant protein aggregates, is frequently seen in pathological structures containing protein aggregates, associated with several neurodegenerative diseases. However, the function of OPTN in these protein aggregates is not known. Here, we have explored the role of OPTN in mutant protein aggregation and in cytoprotection from toxicity of mutant proteins. Mutant huntingtin (mHtt) and mutant ataxin-3 (mAtax-3) showed reduced formation of aggregates in Optn-/- mouse embryonic fibroblasts as compared with wild type cells. Co-expression of OPTN enhanced aggregate formation by mHtt and mAtax-3 in Optn-/- cells. C-terminal domain of OPTN (412-577 amino acids) was necessary and sufficient to promote aggregate formation by these mutant proteins. The E478G mutant of OPTN, defective in ubiquitin-binding and autophagy, was also able to promote aggregation of mHtt and mAtax-3. OPTN and its C-terminal domain form a complex with the chaperone HSP70 known to promote mutant protein aggregation. Overexpression of mHtt or mAtax-3 induced more cell death in Optn-/- cells compared with wild type cells. Importantly, compared to wild type cells, Optn-deficient cells having mHtt or mAtax-3 aggregates showed higher level of cell death in neuronal (N2A) and non-neuronal cells. Our results show that OPTN promotes formation of mutant huntingtin and mutant ataxin-3 aggregates, and this function of OPTN might be mediated through interaction with HSP70 chaperones. Our results also show that OPTN reduces cytotoxicity caused by these mutant protein aggregates. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.02.129783v1?rss=1 Authors: Ramirez de Mingo, D., Lopez-Garcia, P., Hervas, R., Laurents, D. V., Carrion-Vazquez, M. Abstract: The cytoplasmic polyadenylation element-binding protein 3 (CPEB3), is an RNA-binding protein which in its soluble state is localized in membraneless neuronal RNA granules keeping target mRNAs in a repressed state. The stimulus-dependent aggregation of CPEB3 activates target mRNAs translation, a central event for the maintenance of long-term memory-related synaptic plasticity in mammals. To date, the molecular determinants that govern both connected events remain unclear. Here, to gain insight into these processes, the biophysical properties of the human CPEB3 (hCPEB3) are characterized. We found that hCPEB3 homotypic condensation is mainly driven by hydrophobic interactions and occurs under physiological conditions. Moreover, hCPEB3 biomolecular condensates are dynamic inside living cells, whose localization and stabilization are mediated by its RNA-recognition domains. In contrast, the hCPEB3 polar N-terminal region is crucial for hCPEB3 amyloid-like aggregation in vitro, which is disrupted by the polyglutamine binding peptide 1 (QBP1), A{beta}42 seeds and Hsp70, highlighting the importance of the Q4RQ4 tract as well as the hydrophobic residues for hCPEB3 functional aggregation. Based on these findings, we postulate a model for the role of hCPEB3 in memory persistence that advances a rather sophisticated control for hCPEB3 condensate dissociation and amyloid-like formation to achieve its physiological function. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.15.098699v1?rss=1 Authors: Tao, J., Berthet, A., Citron, R., Stanley, R., Gestwicki, J., Agard, D. A., McConlogue, L. Abstract: Over-expression and aggregation of alpha-synuclein (ASyn) are linked to the onset and pathology of Parkinsons disease and related synucleinopathies. Elevated levels of the stress induced chaperone, Hsp70, protects against ASyn misfolding and ASyn-driven neurodegeneration in cell and animal models, yet there is minimal mechanistic understanding of this important protective pathway. It is generally assumed that Hsp70 binds to ASyn using its canonical and promiscuous substrate-binding cleft to limit aggregation. Here we report that this activity is due to a novel and unexpected mode of Hsp70 action, involving neither ATP nor the typical substrate-binding cleft. We use novel ASyn oligomerization assays to show that Hsp70 directly blocks ASyn oligomerization, an early event in ASyn misfolding. Using truncations, mutations and inhibitors, we confirmed that Hsp70 interacts with ASyn via an as yet unidentified, non-canonical interaction site in the C-terminal domain. Finally, a biological role for a non-canonical interaction was observed in H4 neuroglioma cells. Together, these findings suggest that new chemical approaches will be required to target Hsp70-ASyn interaction in synucleinopathies. Such approaches are likely to be more specific than targeting Hsp70 canonical actions. Additionally, these results raise the question of whether other misfolded proteins might also engage via the same non-canonical mechanism. Copy rights belong to original authors. Visit the link for more info

Das ist also jetzt der Jahres-Rückblick im Houseschuh-Mix, mit den Songs, für die du in den letzten zwei Wochen abstimmen konntest. Vielen Dank für deine Stimme. Bei deinen Vorschlägen kristallisierten sich schnell zwei Favoriten heraus: Der Underground-Hit „Coeur De La Nuit“, den ich in HSP41 zum ersten Mal spielte. Und der Superhit „Fade Out Lines“, […] Der Beitrag HSP70 Retrospektive 2014 mit Robin Schulz, The Avener, Coeur De La Nuit, Mendo, Oliver Dollar | Folge 70 Houseschuh Podcast erschien zuerst bei Houseschuh. Verpasse keine Podcast-Folge und werde VIP-Hörer unter houseschuh.com/vip.

ACS Chemical Biology editors highlight articles from Volume 9, Issue 8 and speak with author Tony Taldone (from the lab of Gabriela Chiosis) who reports a new toolset for the investigation of the Hsp70 proteome in cancer.

Listen to Professor Rick Dobrowsky discussing his recent ASN NEURO paper on how Hsp70 induction is sufficient to prevent NRG1 (neuregulin-1 type 1)-induced demyelination by enhancing the proteasomal degradation of c-Jun

Thu, 13 Feb 2014 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/16697/ https://edoc.ub.uni-muenchen.de/16697/1/Li_Zhuo.pdf Li, Zhuo ddc:540, ddc:500, Fakultät für Chemie und Pharmaz

Sarkome stellen eine heterogene Gruppe von mesenchymalen Tumoren mit einem teilweise aggressiven klinischen Verlauf dar. Die biomedizinische Forschung untersucht molekulare Mechanismen, um durch eine gezielte Pharmaka-Modulierung die Effizienz klassischer Behandlungsmethoden zu steigern. Ein vielversprechendes therapeutisches Verfahren basiert auf der Anwendung der Hyperthermie in Kombination mit einer Standardchemotherapie. Die biologischen Auswirkungen der Hyperthermie auf intrazelluläre Prozesse, wie z.B. Signaltransduktionskaskaden, Reparaturmechanismen und Apoptosewege sind bislang nur teilweise erforscht. In der Arbeit wurde die Auswirkung eines Hitzeschocks auf den anti-apoptotischen Akt-mTOR-Signaltransduktionsweg und dessen Bedeutung für die Vitalität der mit Hitze- oder Thermo-Chemotherapie behandelten Krebszellen in vitro untersucht. Anhand der in unterschiedlichen Sarkomzelllinien durchgeführten Analysen konnte festgestellt werden, dass eine Hitzeexposition bei einer klinisch relevanten Temperatur von 41,8°C eine starke Phosphorylierung der Kinasen Akt, mTOR und p70/p85 S6K induziert. Die zeitgleich beobachtete Erhöhung der HSP70-Expression unter einem Hitzeschock deutet auf eine adäquate Antwort der Zellen auf Hitzeschock hin. Die Aktivierung des Akt-mTOR-Signalweges sowie die Induktion von HSP70 wirken anti-apoptotisch. Eine Unterdrückung von PTEN und die resultierende Hyperaktivierung von Akt führten zu einer gesteigerten Proliferation der Zellen. Durch die Hyperaktivierung von Akt konnte die Vitatlität und Koloniebildungsfähigkeit der Zellen nach einem Hitzeschock verbessert werden, was durch Perifosin wiederum unterdrückt werden konnte. Die Anwendung des Akt-Inhibitors Perifosin hat einen stark reduzierenden Effekt auf die konstitutive und Hitzeschock-bedingte Phosphorylierung der Akt-Kinase und ihrer downstream targets. So vermindert Perifosin die Vitalität und das klonogene Überleben von Sarkomzellen, die einem Hitzeschock ausgesetzt wurden. Eine Analyse hinsichtlich des Akt-mTOR-Signalweges in vitro zeigt, dass auch Doxorubicin bei 37°C die Aktivierung der Signalkaskade auslöst. Zusätzlich wird durch Doxorubicin die PARP-Expression verstärkt. Die Kombinationsbehandlung von Sarkomzellen mit Doxorubicin und Perifosin zeigt einen reduzierenden Effekt auf die Akt-Phosphorylierung, sowie die Induktion der PARP-Expression und sensitiviert die Sarkomzellen gegenüber einem Hitzeschock. Darüber hinaus konnte Perifosin die relative Resistenz den Osteosarkom MG63-Zellen und den Fibrosarkom HT1080-Zellen gegenüber Doxorubicin verringern. In Akt-KD-Experimenten konnte dabei gezeigt werden, dass der Effekt von Perifosin spezifisch der Akt-Inhibition zugeschrieben werden kann. Sowohl ein Akt-KD als auch Perifosin führt zu einer Unterdrückung der Phosphorylierung von mTOR und p70/p85 S6K, zu einer Verminderung der Hitze-bedingten HSP70-Induktion und zur Induktion der Apoptose. Die Ergebnisse dieser Arbeit zeigen, dass Akt eine wichtige Rolle in dem intrazellulären Schutzmechanismus und Überleben der dem Hitzeschock ausgesetzten Zellen spielt. Sie deuten auf eine wichtige Rolle des Akt-mTOR-Signalweges bezüglich der Überlebensfähigkeit der Zellen während eines Hitzeschocks hin.

Molecular chaperones of the Hsp70 class are essential for a number of cellular processes. The yeast mitochondrial Hsp70 chaperone Ssc1 plays an indispensable role for the mitochondrial biogenesis. As an essential component of the import motor of the TIM23 transolcase, Ssc1 drives the ATP-dependent translocation of proteins into the mitochondrial matrix. Moreover, it mediates the de novo folding and the assembly of several proteins in the mitochondrial matrix and prevents the formation of protein aggregates. Surprisingly, Ssc1 itself has a propensity to self-aggregate. Thus, it requires a helper protein, the chaperone Hep1 that prevents Ssc1 aggregation and maintains its structure and function. The mechanism of the protective function of Hep1 on Ssc1, however, is not understood. In the present study, the structural determinants of Ssc1 that make it prone to aggregation and the structural requirements of Ssc1 for its interaction with Hep1 were analysed and provided insights into the mechanism of prevention of Ssc1 aggregation by Hep1. The aggregation studies demonstrate that a variant of Ssc1 consisting of the ATPase domain and the subsequent interdomain linker aggregates in absence of Hep1. In contrast, the PBD and the ATPase domain alone are not prone to aggregation. Moreover, the interaction studies reveal that the aggregation-prone region seems to be the smallest entity within Ssc1 required for the interaction with Hep1. Taken together, the native Ssc1 adopts an aggregation-prone conformation, in which the ATPase domain with the interdomain linker has the propensity to aggregate. Hep1 binds to this aggregation-prone region and thereby counteracts the aggregation process and keeps the native Ssc1 in a functional and active state. Although Hsp70 chaperones are important for the biogenesis of a multitude of proteins, little is known about the biogenesis of these chaperones themselves. The present study reports on the analysis of the folding process of the mitochondrial Hsp70 chaperone Ssc1. In organello, in vivo and in vitro assays were established and then employed to study the de novo folding of Ssc1. Upon import into mitochondria, Ssc1 folds rapidly with the ATPase domain and the PBD adopting their structures independently of each other. Notably, the ATPase domain requires the presence of the interdomain linker for its folding, whereas the PBD folds without the linker. Moreover, in the absence of Hep1, the ATPase domain with the interdomain linker displays a severe folding defect, which indicates a role of Hep1 in the folding process of Ssc1. Apart from Hep1, none of the general mitochondrial chaperone systems seem to be important for the folding of Ssc1. Furthermore, the folding process of Ssc1 was reconstituted in vitro and the main steps of the folding pathway of Ssc1 were characterised. Hep1 and ATP/ADP are required and sufficient for the folding of Ssc1 into the native, catalytically active form. In an early step of folding, Hep1 interacts with the folding intermediate of Ssc1. This interaction induces conformational changes which allow binding of ATP/ADP. The binding of a nucleotide triggers Hep1 release and further folding of the intermediate into a native Ssc1. The present study provides the first direct evidence for the requirement of Hep1 for the folding of the Ssc1 chaperone. Thus, it demonstrates for the first time that the de novo folding of an Hsp70 chaperone depends on a specialized proteinaceous factor. In conclusion, Hep1 fulfils a dual chaperone function in the cell. It mediates the de novo folding of Ssc1 and maintains folded Ssc1 in a functional state during the ATPase cycle. Therefore, the Hep1 chaperone plays a crucial role for the protein biogenesis and homeostasis in mitochondria.

Thu, 25 Oct 2012 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/14957/ https://edoc.ub.uni-muenchen.de/14957/1/Fu_Peng.pdf Fu, Peng ddc:610, ddc:600, Medizinische Fakultät

Background: Surfactant protein C (SP-C) is important for the function of pulmonary surfactant. Heterozygous mutations in SFTPC, the gene encoding SP-C, cause sporadic and familial interstitial lung disease (ILD) in children and adults. Mutations mapping to the BRICHOS domain located within the SP-C proprotein result in perinuclear aggregation of the proprotein. In this study, we investigated the effects of the mutation A116D in the BRICHOS domain of SP-C on cellular homeostasis. We also evaluated the ability of drugs currently used in ILD therapy to counteract these effects. Methods: SP-C-A116D was expressed in MLE-12 alveolar epithelial cells. We assessed in vitro the consequences for cellular homeostasis, immune response and effects of azathioprine, hydroxychloroquine, methylprednisolone and cyclophosphamide. Results: Stable expression of SP-C-A116D in MLE-12 alveolar epithelial cells resulted in increased intracellular accumulation of proSP-C processing intermediates. SP-C-A116D expression further led to reduced cell viability and increased levels of the chaperones Hsp90, Hsp70, calreticulin and calnexin. Lipid analysis revealed decreased intracellular levels of phosphatidylcholine (PC) and increased lyso-PC levels. Treatment with methylprednisolone or hydroxychloroquine partially restored these lipid alterations. Furthermore, SP-C-A116D cells secreted soluble factors into the medium that modulated surface expression of CCR2 or CXCR1 receptors on CD4(+) lymphocytes and neutrophils, suggesting a direct paracrine effect of SP-C-A116D on neighboring cells in the alveolar space. Conclusions: We show that the A116D mutation leads to impaired processing of proSP-C in alveolar epithelial cells, alters cell viability and lipid composition, and also activates cells of the immune system. In addition, we show that some of the effects of the mutation on cellular homeostasis can be antagonized by application of pharmaceuticals commonly applied in ILD therapy. Our findings shed new light on the pathomechanisms underlying SP-C deficiency associated ILD and provide insight into the mechanisms by which drugs currently used in ILD therapy act.

Meme kanserine dair çalışması Türk basınında yer bulan Doç. Dr. Tan İnce ile araştırmaları hakkında görüştük. Doç. Dr. Tan İnce Dr. Tan İnce şu anda Miami Üniversitesi'ne bağlı Miller Tıp Fakültesi'nde Multidisipliner (Çokyaklaşımlı) Kök Hücre Enstitüsü'nde Tümör Kök Hücreleri bölümünü yönetiyor. Kendisine söyleşi için yeniden teşekkür ederiz. Notlar Dr Tan İnce ve ekibinin, bu söyleşide tartıştığımız son makalesi şu: Sandra Santagata vd., 2011. High levels of nuclear heat-shock factor 1 (HSF1) are associated with poor prognosis in breast cancer. Proceedings of the National Academy of Sciences of the United States of America 108:18378-18383. Bu makaleye dair İngilizce basın açıklamasını buradan okuyabilirsiniz. Dr İnce'nin daha önce geliştirdiği kanser hücresi kültürünün makalesi: Tan A. Ince vd., 2007. Transformation of Different Human Breast Epithelial Cell Types Leads to Distinct Tumor Phenotypes. Cancer Cell 12:160-170. HSF1'in bu makalede tartışılan rolünün tarif edildiği makale: Chengkai Dai vd., 2007. Heat Shock Factor 1 Is a Powerful Multifaceted Modifier of Carcinogenesis. Cell 130:1005-1018. Bu makale Dr İnce ile işbirligi yapan Dr Susan Lindquist ekibinin çalışmasını tarif ediyor. HSF1'in rolünü Şekil 1'deki çizimle anlatmaya çalıştım: (A) HSF1, hücre içinde ama çekirdek dışında HSP70 ve HSP90 gibi protenlerle bir arada bulunur. Bu esnada HSF1 henüz etkin değildir. Hücre çeşitli olumsuz fiziksel/kimyasal şartlar altındayken hücre içindeki elverişsiz ortam, çeşitli proteinlerin yapısal özelliklerini ve işlevlerini kaybetmesine yol açar. (B) Bu bozuk proteinlerin temizlenmesi görevi HSP70 ve HSP90 gibi proteinlere düşer. Bu sırada HSF1 bunlarla temasını kaybeder, çekirdek içine aktarılır, etkinleştirilir ve oradaki DNA'ya bağlanır. (C) HSF1, hücreye daha çok HSP70 ve HSP90 ürettirerek elverişsiz ortam ile başa çıkmasını sağlar. Bu esnada hücrenin içindeki ortamın kötüleşmesine (ya da iyileşmesine) bağlı olarak çekirdek içindeki HSF1 miktarı da artacaktır (veya azalacaktır). Şekil 1. HSF1,in hücre içindeki rolü (ölçeksiz çizilmiştir)

Folding of newly synthesized proteins is an essential part of protein biosynthesis and misfolding can result in protein aggregation which can also lead to several severe diseases. Protein folding is a highly heterogeneous process and rarely populated intermediate states may play an important role. Single-molecule techniques are ideally suited to resolve these heterogeneities. In this thesis, I have employed a variety of single-molecule fluorescence spectroscopy techniques to study protein folding using model systems on different levels of complexity. The acidic compact state (A state) of Myo- globin is used as a model system of a protein folding intermediate and is studied by a combination of molecular dynamics (MD) simulations and several fluorescence spectroscopic techniques. Using two-focus fluorescence correlation spectroscopy (FCS), it is shown that the A state is less compact than the native state of myoglobin, but not as expanded as the fully unfolded state. The analysis of exposed hydrophobic regions in the acidic structures generated by the MD simulations reveals poten- tial candidates involved in the aggregation processes of myoglobin in the acidic compact state. These results contribute to the understanding of disease-related fibril formation which may lead ultimately to better treatments for these diseases. A huge machinery of specialized proteins, the molecular chaperones, has evolved to assist protein folding in the cell. Using single molecule fluorescence spectroscopy, I have studied several members of this machinery. Single-pair fluorescence resonance energy transfer (spFRET) experiments probed the conformation of the mitochondrial heat shock protein 70 (Hsp70), Ssc1, in different stages along its functional cycle. Ssc1 has a very defined conformation in the ATP state with closely docked domains but shows significantly more heterogeneity in the presence of ADP. This heterogeneity is due to binding and release of ADP. The nucleotide-free state has less inter-domain contacts than the ATP or ADP-bound states. However, the addition of a substrate protein decreases the interaction between the domains even further simultaneously closing the substrate binding lid, showing that substrate binding plays an active role in the remodeling of Ssc1. This behavior is strikingly different than in DnaK, the major bacterial Hsp70. In DnaK, complete domain undocking in the presence of ADP was observed, followed by a slight re-compaction upon substrate binding. These differences may reflect tuning of Ssc1 to meet specific functions, i.e. protein import into mitochondria, in addition to protein folding. Ssc1 requires the assistance of several cofactors depending on the specific task at hand. The results of spFRET experiments suggest that the cofactors modulate the conformation of Ssc1 to enable it to perform tasks as different as protein import and protein folding. Downstream of Hsp70 in the chaperone network, the GroEL/ES complex is a highly specialized molecular machine that is essential for folding of a large subset of proteins. The criteria that distin- guish proteins requiring the assistance of GroEL are not completely understood yet. It is shown here that GroEL plays an active role in the folding of double-mutant maltose binding protein (DM-MBP). DM-MBP assumes a kinetically trapped intermediate state when folding spontaneously, and GroEL rescues DM-MBP by the introduction of entropic constraints. These findings suggest that proteins with a tendency to populate kinetically trapped intermediates require GroEL assistance for folding. The capacity of GroEL to rescue proteins from such folding traps may explain the unique role of GroEL within the cellular chaperone machinery.

Upon emerging from the ribosomal exit tunnel, folding of the polypeptide chain is necessary to form the fully functional protein. In E. coli, correct and efficient protein folding is mainly secured by an organized and complex chaperone system which includes two main principles: The first principle consists of the nascent binding chaperones including trigger factor (TF) and the DnaK/DnaJ system, while the second principle is represented by the downstream GroEL/ES chaperonin system. The identification of ~250 natural GroEL substrates demonstrated that GroEL/ES specifically folds a small group of proteins with complex domain topologies (Kerner et al., 2005) which include some essential proteins. Although the structural, functional and mechanistic aspects of DnaK, the E. coli Hsp70 chaperone, have been extensively studied, a systematic profiling of the natural DnaK substrates is still missing. Moreover, the cooperation between the two main chaperone systems remains to be elucidated. Here we analyzed the central role of DnaK in the bacterial chaperone network and its cooperation with the ribosome-associated chaperone TF and the downstream chaperonin GroEL/GroES using SILAC-based proteomics of DnaK-pulldowns. In parallel, we also analyzed the changes at the global proteome level under conditions of single or combined chaperone deletion. Our measurements show that DnaK normally interacts with at least ~700 newly-synthesized and pre-existent proteins (~30 % of all cytosolic proteins), including ~200 aggregation-prone substrates. Individual deletion of TF or depletion of GroEL/ES at 30 oC-37 oC leads to limited but highly specific changes in the DnaK interactome and in global proteome composition. Specifically, loss of TF results in increased interaction of DnaK with ribosomal and other small, basic proteins, and in a specific defect in the biogenesis of outer membrane -barrel proteins. While deletion of DnaK/DnaJ leads to the degradation or aggregation of ~150 highly DnaK-dependent proteins of large size, massive proteostasis collapse is only observed upon combined deletion of the DnaK system and TF, and is accompanied by extensive aggregation of GroEL substrates and ribosomal proteins. We conclude that DnaK is a central hub in the cytosolic E. coli chaperone network, interfacing with the upstream TF and the downstream chaperonin. These three major chaperone machineries have partially overlapping and non-redundant functions.

To become biologically active, a protein must fold into a distinct three-dimensional structure. Many non-native proteins require molecular chaperones to support folding and assembly. These molecular chaperones are important for de novo protein folding as well as refolding of denatured proteins under stress conditions. A certain subset of chaperones, the chaperonins, are required for the folding of the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco); furthermore, correct folding of Rubisco is also aided by the Hsp70 chaperone system. Rubisco catalyzes the initial step of CO2 assimilation in the Calvin-Benson-Bassham (CBB) cycle. Unfortunately, this enzyme is extremely inefficient, not only does it exhibit a slow catalytic rate (three CO2 molecules fixed per second per Rubisco) but it also discriminates poorly between the assimilation of CO2 and O2 to its sugar-phosphate substrate ribulose-1,5-bisphosphate (RuBP), the latter resulting in loss of photosynthetic efficiency. Due to these inefficiencies, carbon fixation by Rubisco is the rate limiting step of the CBB cycle. Photosynthetic organisms must produce tremendous amounts of Rubisco to alleviate these shortcomings; therefore significant quantities of nitrogen stores are invested in the production of Rubisco making Rubisco the most abundant protein on earth. These drawbacks of Rubisco have important implications in increasing CO2 concentrations and temperatures in the context of global warming. The ability to engineer a more efficient Rubisco could potentially reduce photosynthetic water usage, increase plant growth yield, and reduce nitrogen usage is plants. However, eukaryotic Rubisco cannot fold and assemble outside of the chloroplast, hindering advancements in creating a more efficient Rubisco. Form I Rubisco, found in higher plants, algae, and cyanobacteria, is a hexadecameric complex consisting of a core of eight ~50 kDa large subunits (RbcL), which is capped by four ~15 kDa small subunits (RbcS) on each end. The discovery of a Rubisco-specific assembly chaperone, RbcX, has lead to a better understanding of the components necessary for the form I Rubisco assembly process. RbcX is a homodimer of ~15 kDa subunits consisting of four α- helices aligned in an anti-parallel fashion along the α4 helix. RbcX2 functions as a stabilizer of folded RbcL by recognizing a highly conserved C-terminal sequence of RbcL: EIKFEFD, termed the C-terminal recognition motif. As has been demonstrated by studies of cyanobacterial Rubisco, de novo synthesized RbcL is folded by the chaperonins, whereupon RbcX2 stabilizes the folded RbcL monomer upon release from the folding cavity and then assists in the formation of the RbcL8 core. RbcX2 forms a dynamic complex with RbcL8 and as a result, RbcX2 is readily displaced by RbcS docking in an ATP-independent manner, thereby creating the functional holoenzyme. However, the exact mechanism by which RbcS binding displaces RbcX2 from the RbcL8 core is still unknown. Furthermore, though much advancement has been made in the understanding of form I Rubisco folding and assembly, an exact and detailed mechanism of form I Rubisco assembly is still lacking. The highly dynamic complex of RbcL/RbcX is critical for the formation of the holoenzyme; however it has hindered attempts to characterize critical regions of RbcL that interact with the peripheral regions of RbcX2. An important observation arose when heterologous RbcL and RbcX2 components interacted; a stable complex could form enabling in depth characterization of the RbcL/RbcX2 interaction. In the present study, the detailed structural mechanism of RbcX2-mediated cyanobacterial form I Rubisco assembly is elucidated. To obtain molecular insight into the RbcX2-mediated assembly process of cyanobacterial form I Rubisco, cryo-EM and crystallographic studies in concert with mutational analysis were employed by taking advantage of the high affinity interaction between RbcL and RbcX2 in the heterologous system (Synechococcus sp. PCC6301 RbcL and Anabaena sp. CA RbcX2). Structure guided mutational analysis based on the 3.2 Å crystal structure of the RbcL8/(RbcX2)8 assembly intermediate were utilized to determine the precise interaction site between the body of RbcL and the peripheral region of RbcX2. From these studies a critical salt bridge could be identified that functions as a guidepoint for correct dimer formation, and it was observed that RbcX2 exclusively mediates Rubisco dimer assembly. Furthermore, the mechanism of RbcX2 displacement from the RbcL8 core by RbcS binding was elucidated as well as indications of how RbcS docking on the RbcL8 core is imperative for full form I Rubisco catalytic function by stabilizing the enzymatically competent conformation of an N-terminal loop of Rubisco termed the ‘60ies loop’. Finally, initial attempts in in vitro reconstitution of eukaryotic Rubisco are reported along with the characterization of Arabidopsis thaliana RbcX2 binding to the C-terminal recognition motif of the Rubisco large subunit from various species.

Protein folding is a crucial process for cell survival. Only natively structured proteins can perform their essential biological functions. Although all structure-relevant information is principally encoded in the amino acid sequence of a protein, the efficient folding of many larger proteins depends on the assistance of molecular chaperones. These proteins bind reversibly to exposed hydrophobic sequences in folding intermediates, thereby preventing aggregation and supporting effective folding. The Hsp70 family proteins constitute key components of the cellular chaperone network in eukaryotes and bacteria. They are involved in diverse protein processing reactions, reaching from folding and assembly of nascent polypeptides to protein transport across membranes. Regular Hsp70s consist of an N-terminal nucleotide binding domain (NBD) and an allosterically coupled C-terminal substrate binding domain, which is further divided into a beta-sandwich domain and a three helix bundle domain (3HBD). Hsp70s perform their cellular functions through ATP-driven cycles of substrate binding and release: In the ATP state, peptide binding is dynamic. ATP hydrolysis results in a dramatic structural rearrangement, leading to a conformation in which hydrophobic peptide segments are locked between 3HBD and beta-sandwich domain. Thus, substrate proteins are stably bound in the ADP and apo state. This Hsp70 folding cycle is tightly controlled by a large complement of cochaperones. Whereas J-domain proteins recruit substrates and trigger ATP hydrolysis, nucleotide exchange factors (NEFs) accelerate ADP release. In eukaryotes, four evolutionarily unrelated classes of Hsp70 NEFs have been identified, among which Hsp110 homologs are most abundant. As judged by their conserved domain composition, Hsp110s derive from canonical Hsp70s, but have evolved into NEFs, preserving the ability to stabilize misfolded proteins in solution. In the present study, the cooperation of Hsp70 and Hsp110 molecular chaperones in protein folding was investigated. First, the crystal structure of a functional complex between the yeast Hsp110 homolog Sse1p and the NBD of human Hsp70 was determined. The structure was solved by selenium multiple wavelength anomalous diffraction and refined at 2.3 Å resolution to a crystallographic R-factor of 19.7 %. The structure of Sse1p is characterized by extended domain-domain interactions. Beta-sandwich domain and 3HBD are arranged along the NBD and point into opposite directions. Importantly, Sse1p has ATP bound, a prerequisite for efficient complex formation with Hsp70. In the complex, the NBD and 3HBD of Sse1p embrace the Hsp70 NBD, thereby opening the nucleotide binding cleft of Hsp70 and releasing ADP. In a subsequent mutational analysis, key features of the chaperone complex were targeted. Specifically, amino acid exchanges were introduced (i) in the areas of close surface contacts between Sse1p and Hsp70N, (ii) at the interfaces between individual Sse1p domains, (iii) in the nucleotide binding pocket of Sse1p, and (iv) at the putative substrate binding site in the beta-sandwich domain of Sse1p. Sse1p mutations affecting the interaction between the Hsp70 NBD and the Sse1p 3HBD strongly impaired Hsp70 complex formation and nucleotide exchange. Consistently, these Sse1p variants were less effective than wildtype (wt) Sse1p in supporting substrate release from Hsp70 and Hsp70-mediated refolding of thermally denatured firefly luciferase. In vivo, the respective sse1 mutations caused severe stress and a pronounced growth defect, likely because of reduced substrate flux through the Hsp70 machinery. Taken together, these results define nucleotide exchange on Hsp70 as the main function of Sse1p. Furthermore, they highlight the importance of the interaction between the Hsp70 NBD and the Sse1p 3HBD for the nucleotide exchange activity of Sse1p. No evidence was found for an ATP-driven, Hsp70-like conformational cycle of Sse1p. Mutations targeting the Sse1p inter-domain communication and the ATPase activity did not impair Sse1p function in vitro and in vivo. Mutations at the putative substrate binding cleft of Sse1p aggravated the functional defect of partially NEF-deficient Sse1p mutants in vitro and in vivo. Thus, direct substrate interactions mediated by the beta-sandwich domain may support Hsp70-assisted protein folding in addition to the nucleotide exchange function of Sse1p. According to our mutational analysis, Hsp110s contribute to Hsp70-assisted protein folding in two ways: Their major function is the acceleration of ADP dissociation from Hsp70 by stabilizing the Hsp70 NBD in an open conformation with low affinity for the nucleotide. Consequently, Hsp110s support the rapid conformational cycling of Hsp70 and thus efficient substrate binding and release. In addition, Hsp110s may directly interact with the unfolded substrate upon binding to Hsp70. By holding the misfolded protein chain, Hsp110s might cooperatively aid Hsp70 in remodeling the substrate via large-scale thermal motions of the Hsp70 PBD.

Background: Membrane-bound heat shock protein 70 (Hsp70) serves as a tumor-specific recognition structure for Hsp70-peptide (TKD) plus IL-2 activated NK cells. A phase I clinical trial has shown that repeated re-infusions of ex vivo TKD/IL-2-activated, autologous leukapheresis product is safe. This study investigated the maintenance of the cytolytic activity of NK cells against K562 cells and autologous tumor after 6 plus 3 infusions of TKD/IL-2-activated effector cells. Methods: A stable tumor cell line was generated from the resected anastomotic relapse of a patient with colon carcinoma (pT3, N2, M0, G2). Two months after surgery, the patient received the first monthly i.v. infusion of his ex vivo TKD/IL-2-activated peripheral blood mononuclear cells (PBMNC). After 6 infusions and a pause of 3 months, the patient received another 3 cell infusions. The phenotypic characteristics and activation status of tumor and effector cells were determined immediately before and at times after each infusion. Results: The NK cell ligands Hsp70, MICA/B, and ULBP-1,2,3 were expressed on the patient's anastomotic relapse. An increased density of activatory NK cell receptors following ex vivo stimulation correlated with an enhanced anti-tumoricidal activity. After 4 re-infusion cycles, the intrinsic cytolytic activity of non-stimulated PBMNC was significantly elevated and this heightened responsiveness persisted for up to 3 months after the last infusion. Another 2 re-stimulations with TKD/IL-2 restored the cytolytic activity after the therapeutic pause. Conclusion: In a patient with colon carcinoma, repeated infusions of ex vivo TKD/IL-2-activated PBMNC initiate an intrinsic NK cell-mediated cytolytic activity against autologous tumor cells.

Ziel dieser Dissertation war es, die Funktionen des rekombinanten humanen Hitzeschock-Protein 70 (rhuHsp70) in der durch dendritischen Zellen (DCs) vermittelten innaten und adaptiven Immunantwort zu untersuchen. Intrazellular hat das Hitzeschock-Protein 70 vielfältige Funktionen unter anderem bei der Proteinfaltung und der Verhinderung von Aggregationen. Die Rolle des extrazellulären Hsp70 im Immunsystem ist Gegenstand der aktuellen Forschung. Aufgrund seiner verschiedenen beschriebenen Funktionen, die die innate Aktivierung von von immunkompetenten Zellen, wie DCs, und die effiziente Präsentierung von gebundenen Antigenen umfassen, wurde ein bedeutendes thera-peutisches Potential des rekombinanten oder aus Tumormaterial isolierten Hsp70 für die immun-basierte Tumortherapie postuliert. Allerdings gibt es zu der Rolle von Hsp70 im Immunsystem widersprüchliche Daten. Mit dem Nachweis von Kontaminationen in dem für viele Studien verwendeten rekombinanten Hsp70, die auf die E.coli Kultur zurückgeführt wurden, wurden die Funktionen von Hsp70 angezweifelt. Welches therapeutisches Potential Hsp70 tatsächlich hat, war offen. Im Rahmen dieser Arbeit wurde gezeigt, dass rhuHsp70 die Kreuzpräsentation von Peptidantigenen signifikant steigerte. Durch den Vergleich von gleichen Mengen Peptid-antigen, allein oder im Komplex mit rhuHsp70, wurde zum ersten Mal die Steigerung durch rhuHsp70 quantifiziert. Dabei zeigte rhuHsp70 selbst keine Signal-Funktion auf die DCs. RhuHsp70 induzierte keinen intrazellulären Einstrom von Calciumionen, induzierte nicht die phänotypische Maturierung, aktivierte nicht Zytokinsektretion und veränderte nicht die Makropinozytoseeigenschaften der DCs. Demnach hat rhuHsp70 keine dem einem Maturierungssignal vergleichbaren Eigenschaften. Die Ergebnisse dieser Arbeit verdeutlichen, dass die Reinheit des verwendeten rhuHsp70 entscheidend für die korrekte Schlussfolgerung und Interpretation der experimentellen Ergebnisse ist. Schon geringe Mengen an Kontaminationen wie Endotoxine haben stimulatorische Aktivität auf DCs, die fälschlicherweise dem rhuHsp70 zugeschrieben wird. Mit dieser Arbeit wurde erstmals nachgewiesen, dass die in den rhuHsp70 Präparationen in nanomolaren Konzentrationen enthaltenen freien Nukleotide und nicht rhuHsp70 selbst den intrazellulären Einstrom von Calciumionen in DCs induzieren. Bis dato wurden die Nukleotide nicht als Ursache für das mit Hsp70 induzierte Calciumsignal beachtet. Mit der vorliegenden Arbeit wurde weiterhin gezeigt, dass die Funktion von rhuHsp70 in der Kreuzpräsentation nicht an eine innate Signalfunktion gebunden ist. Durch eine bisher nicht durchgeführte Verknüpfung von biochemischer Analyse der Substrat- rhuHsp70 Interaktionen und immunologischer Antigenpräsentation wurde als wichtige Voraussetzung für die Verbesserung der Kreuzpräsentation die Komplexbildung zwischen Peptid und rhuHsp70 nachgewiesen. Die gesteigerte Kreuzpräsentation korreliert direkt mit der biochemischen Komplexbildung. Dabei war die rhuHsp70 vermittelte Steigerung unabhängig von TAP, Sec61 und der Ansäuerung der endolysosomalen Kompartimente. Die Kreuzpräsentation von verschiedenen Peptiden mit unterschiedlichen Prozessierungsbedingungen wurde durch Bindung an rhuHsp70 verstärkt. Es wurde gezeigt, dass mehr Peptidantigen in den APCs vorhanden war, die mit rhuHsp70:Peptid inkubiert wurden, im Vergleich zu den APCs, die mit der gleichen Menge Peptid ohne rhuHsp70 inkubiert wurden. Darüber hinaus wurde untersucht, ob die verbesserte Kreuzpräsentation der Peptid-antigene durch rhuHsp70 auch zu einer Zunahme von Antigen-spezifischen T-Zellen unter Primingbedingungen führt. Dabei wurden beim Priming mit rhuHsp70:Peptid gepulsten DCs im Vergleich zu Peptid gepulsten DCs weniger oder gleich viel Antigen-spezifische IFN-g und Perforin sezernierenden Zellen erhalten. Bemerkenswert ist, das die Zellen aus dem Primingansatz mit den rhuHsp70:Peptid gepulsten DCs eine deutlich bessere Antigenspezifität als die Zellen aus dem Primingansatz mit Peptid gepulsten DCs aufwiesen. Die Quantifizierung der Zusammensetzung der geprimten Zellpopulation ergab, dass mit rhuHsp70:Peptid gepulsten im Vergleich zu Peptid gepulsten DCs weniger CD8+ T-Zellen erhalten wurden. Konsistent wurde eine Zunahme der CD3+CD4+ T-Zellen beobachtet. Innerhalb dieser CD3+CD4+ T-Zellpopulation war der Anteil der FOXP3+ T-Zellen in den Ansätzen mit rhuHsp70:Peptid gepulsten DCs erhöht, aber es wurde hierbei keine konsistente Zunahme der CD25++FOXP3+ Zellen beobachtet. Ausgehend von den Ergebnissen dieser Arbeit ergeben sich neue interessante Fragen zu der Interaktion von rhuHsp70 mit dem Immunsystem. So ist zu klären, welche Funktionen die durch das Priming mit rhuHsp70:Peptid Komplex gepulsten DCs entstehenden CD4+ T-Zellen ausüben. Wichtig ist auch, den Grund der besseren Antigenspezifität der mit rhuHsp70:Peptid Komplex geprimten Zellen zu untersuchen.

To become biologically active, proteins have to acquire their correct three-dimensional structure by folding, which is frequently followed by assembly into oligomeric complexes. Although all structure relevant information is contained in the amino acid sequence of a polypeptide, numerous proteins require the assistance of molecular chaperones which prevent the aggregation and promote the efficient folding and/or assembly of newly-synthesized proteins. The enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), which catalyzes carbon fixation in the Calvin-Benson-Bassham cycle, requires chaperones in order to acquire its active structure. In plants and cyanobacteria, RuBisCO (type I) is a complex of approximately 550 kDa composed of eight large (RbcL) and eight small (RbcS) subunits. Remarkably, despite the high abundance and importance of this enzyme, the characteristics and requirements for its folding and assembly pathway are only partly understood. It is known that folding of RbcL is accomplished by chaperonin and most likely supported by the Hsp70 system, whereas recent findings indicate the additional need of specific chaperones for assembly. Nevertheless, this knowledge is incomplete, reflected by the fact that in vitro reconstitution of hexadecameric RuBisCO or synthesis of functional plant RuBisCO in E. coli has not been accomplished thus far. In this thesis, attempts to reconstitute type I RuBisCO in vitro did not result in production of active enzyme although a variety of reaction conditions and additives as well as chaperones of different kind, origin and combination were applied. The major obstacle for reconstitution was found to be the incapability to produce RbcL8 cores competent to form RbcL8S8 holoenzyme. It could be shown that the RbcL subunits interact properly with the chaperonin GroEL in terms of binding, encapsulation and cycling. However, they are not released from GroEL in an assembly-competent state, leading to the conclusion that a yet undefined condition or (assembly) factor is required to shift the reaction equilibrium from GroEL-bound RbcL to properly folded and released RbcL assembling to RbcL8 and RbcL8S8, respectively. Cyanobacterial RbcX was found to promote the production of cynanobacterial RbcL8 core complexes downstream of chaperonin-assisted RbcL folding, both in E. coli and in an in vitro translation system. Structural and functional analysis defined RbcX as a homodimeric, arc-shaped complex of approximately 30 kDa, which interacts with RbcL via two distinct but cooperating binding regions. A central hydrophobic groove recognizes and binds a specific motif in the exposed C-terminus of unassembled RbcL, thereby preventing the latter from uncontrolled misassembly and establishing further contacts with the polar peripheral surface of RbcX. These interactions allow optimal positioning and interconnection of the RbcL subunits, resulting in efficient assembly of RbcL8 core complexes. As a result of the highly dynamic RbcL-RbcX interaction, RbcS can displace RbcX from the core-complexes to produce active RbcL8S8 holoenzyme. Species-specific co-evolution of RbcX with RbcL and RbcS accounts for limited interspecies exchangeability of RbcX and for RbcX-supported or -dependent assembly modes, respectively. In summary, this study helped to specify the problem causing prevention of proper in vitro reconstitution of type I RuBisCO. Moreover, the structural and mechanistic properties of RbcX were analyzed, demonstrating its function as specific assembly chaperone for cyanobacterial RuBisCO. Since the latter is very similar to RuBisCO of higher plants, this work may not only augment the general understanding of type I RuBisCO synthesis, but it might also contribute to advancing the engineering of catalytically more efficient crop plant RuBisCO both in heterologous systems and in planta.

To become biologically active, most proteins need to fold into precise three dimensional structures. It has been well established that all the folding information is contained within the primary structure of a protein. However, the mechanisms utilized by proteins to avoid sampling the extraordinarily large amount of possible conformations during their folding process are just beginning to be understood. Molecular chaperones assist the folding of newly synthesized and denatured proteins in acquiring their native state in the crowded intracellular environment. As a nascent chain leaves the ribosome, it is captured first by the upstream chaperones and then possibly transferred to the downstream chaperonins. GroEL-GroES, the Hsp-60 of E.coli, is one of the best studied chaperone systems. An appreciable amount of data is available providing information regarding its structure and function. GroEL encapsulates the substrate into the central cavity where folding occurs unimpaired by aggregation and unwanted inter-molecular interactions. Nevertheless, many important aspects of the GroEL mechanism remain to be addressed. Some of the open questions we have addressed in this study include: In what conformation does a substrate protein bind to the apical domains of GroEL; how is it that GroEL is able to accelerate the rate of folding of certain proteins, and how do the conformational properties of the substrate change as it undergoes repeated cycling. By using ensemble FRET and Sp-FRET (Single Pair-Fluorescence Resonance Energy Transfer), we have probed the conformation of the model substrate DM-MBP (Double Mutant Maltose Binding Protein) during different stages of the functional cycle of GroEL. With Sp-FRET coupled to PIE (Pulsed Interleaved Excitation), we have been able to explore the heterogeneity of the GroEL bound substrate protein and observed a bimodal conformational distribution. One of the two populations is as compact as the native state, whereas the other is as extended as the unfolded protein in denaturant. This unfolding is a local phenomena and can also be observed when the substrate is transferred from DnaK/J system (bacterial Hsp70) to GroEL, indicating the possibility of the existence of this conformational heterogeneity in vivo as the protein follows the cellular chaperone pathway. Subsequent to GroEL binding, there is a transient expansion of the protein upon binding of ATP to GroEL, followed by compaction when GroES triggers the encapsulation of the protein inside the chaperonin cage. This transient expansion is however found not to be a necessary event for the rate acceleration of DM-MBP folding, since ADP-AlFx (transition state analogue of ATP hydrolysis) results in a much slower rate of expansion, which does not cause a change in the folding rate. Anisotropy measurements, probing the freedom of motion of different regions of the GroEL bound protein, revealed that there is a segmental release of the substrate protein from the GroEL surface upon binding of ATP and GroES. As a consequence, the hydrophobic collapse of the protein upon encapsulation by GroES follows a step-wise mechanism. In this process, less hydrophobic regions are released upon binding of ATP, prior to more hydrophobic ones which are released only by GroES binding. Thus, the order of Hydrophobic collapse is reversed as compared to spontaneous folding possibly resulting in conformationally different folding intermediates. Evidence that the folding pathway inside the cage differs from that of spontaneous folding was obtained by observing the effect of external perturbations (e.g. mutations in substrate protein and use of different solvent conditions) on the rate of spontaneous and GroEL assisted folding reactions. These two folding reactions respond differently to the introduced perturbations. Kinetic data obtained from ensemble FRET measurements suggest that the conformation of refolding intermediate is altered by the GroEL cavity, which leads to a folding pathway that is different from the spontaneous refolding pathway. In summary, this study revealed significant novel aspects of the GroEL folding mechanism and provided insights into the basis of rate acceleration of the substrate protein by the chaperonin. This work may thus contribute to advance our fundamental knowledge of the chaperonin system and the basic mechanism of protein folding.

Polyglutaminerkrankungen sind neurodegenerative Erkrankungen mit fatalem Verlauf, die sich durch selektive neuronale Degeneration und die Bildung intrazellulärer Aggregate auszeichnen. Verursacht werden sie durch eine Expansion einer Polyglutaminsequenz in einem für die Erkrankung spezifischen Protein, die Fehlfaltung und Aggregation des entsprechenden Proteins bewirkt. Die Aggregation wirkt dabei neurotoxisch, wobei Toxizität hauptsächlich durch lösliche Intermediate des Aggregationsprozesses vermittelt wird. Zur Untersuchung der frühen Aggregationsphase und der späteren Elongationsphase wurden in dieser Arbeit verschiedene fluoreszenzbasierte Methoden etabliert. Mit Hilfe dieser Methoden konnte gezeigt werden, dass nach proteolytischer Spaltung von GST-Htt-Exon1 das Monomer eine Konformationsumlagerung durchmacht, die von einer Dimerisierung oder Oligomerisierung gefolgt wird. Dimere oder Oligomere bilden dabei eine kompakte Struktur aus. Wachstum der Fibrillen erfolgt durch Anlagerung von Monomeren oder einer anderen bisher nicht identifizierten Spezies. Durch Distanzmessungen innerhalb verschiedener Spezies konnte gezeigt werden, dass unlösliche Spezies eine kompakte Struktur aufweisen, die spezifisch für unlösliche Spezies ist. Lösliche Spezies liegen dagegen in einer expandierteren Konformation vor. Molekulare Chaperone üben oftmals eine protektive Funktion auf Neuronen in neurodegenerativen Erkrankungen aus. In dieser Arbeit wurde untersucht, inwieweit das eukaryontische Chaperonin TRiC, das in einem RNA-interference screen als potentieller Suppressor der Huntingtin-Aggregation identifiziert wurde, Aggregation modulieren kann. Gereinigtes TRiC hat keinen Einfluss auf die frühe Phase der Htt-Exon1-Aggregation, vielmehr inhibiert es die Elongation von fibrillären Strukturen, indem es mit Htt-Exon1-Oligomeren interagiert. Diese Interaktion ist transient und ATP-unabhängig. Im Gegensatz dazu interagiert TRiC in Kooperation mit dem Hsp70/40-System mit Htt-Exon1-Monomeren und verhindert die Nukleation der Aggregation. Stattdessen wird ein „gefaltetes“ Htt-Exon1-Produkt mit einer neuartigen Konformation gebildet, das löslich, nicht-fibrillär und nicht-toxisch ist und ~500 kDa-Oligomere ausbildet. Diese Interaktion ist kooperativ, sequentiell und benötigt ATP, ähnelt also der kooperativen Interaktion von TRiC und Hsp70/40 in der de novo-Proteinfaltung und stellt möglicherweise einen natürlichen Faltungsweg für Huntingtin dar.

Tue, 8 May 2007 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/6907/ https://edoc.ub.uni-muenchen.de/6907/1/Hellwig_Alice.pdf Hellwig, Alice ddc:540, ddc:500, Fakultät für Chemie und Pharmazie

Mitochondriales Hsp70 spielt eine wichtige Rolle bei der Biogenese und Funktion von Mitochondrien. Es ist essenziell für den Import, die Faltung und den Abbau mitochondrialer Proteine. Wie alle Hsp70-Proteine arbeitet mtHsp70 dabei mit Cochaperonen zusammen. In dieser Arbeit wurden neue Interaktionspartner von mtHsp70 identifiziert und funktionell charakterisiert. MtHsp70 ist die zentrale Komponente des Importmotors der TIM23-Translokase, der den ATP-abhängigen Transport von Proteinen über die Innenmembran der Mitochondrien vermittelt. Mit Tim14 und Mdj2 wurden in dieser Arbeit zwei Proteine des Importmotors als J-Cochaperone identifiziert. Sowohl Tim14 als auch Mdj2 wurden als MBP-Fusionsproteine aus E. coli gereinigt und stimulierten die ATPase-Aktivität von mtHsp70. Eine Variante von Tim14 mit einer Mutation im HPD-Motiv, die die Stimulation der ATPase-Aktivität von mtHsp70 durch Tim14 verhindert, konnte die Funktion von Tim14 in Hefezellen nicht übernehmen. Die Entdeckung von membranassoziierten J-Proteinen im Importmotor macht deutlich, dass mtHsp70 durch die Stimulation seiner ATPase-Aktivität effizient an ein importiertes Protein binden kann, sobald dieses die Translokationspore des TIM23- Komplexes verlässt. Ebenso wird die evolutionäre Konservierung zwischen dem Importmotor und bakteriellen Hsp70-Systemen ersichtlich. Der Importmotor der TIM23-Translokase ist aber eine Ausnahme unter den Hsp70-Systemen, da in diesem System mit Tim16 eine weitere, regulatorische Komponente identifiziert werden konnte. Tim16 ist ein J-ähnliches Protein, das selber keine stimulierende Wirkung auf die ATPase-Aktivität von mtHsp70 hat, aber die Stimulation von mtHsp70 durch Tim14 reguliert. Dies könnte einen unnötigen Verbrauch von ATP durch mtHsp70 in Abwesenheit eines Präproteins verhindern. Mit der Charakterisierung der J- und J-ähnlichen Proteine des Importmotors wurden wesentliche Erkenntnisse über die Funktionsweise des Importmotors geliefert. Ein bisher nicht bekanntes Protein wurde zusammen mit mtHsp70 aus S. cerevisiae gereinigt und anschließend biochemisch charakterisiert. Dieses Protein, Hep1, ist ein lösliches Protein der mitochondrialen Matrix. Es interagiert mit mtHsp70 in seiner nukleotidfreien und ADPgebundenen Form. Für diese Interaktion ist die ATPase-Domäne von mtHsp70 notwendig. Jedoch trägt vermutlich auch die PBD zur Bindung von mtHsp70 an Hep1 bei, da eine solche Bindung nur beobachtet werden konnte, wenn mtHsp70 sowohl die ATPase-Domäne als auch die PBD aufweist. Hep1 hat im Gegensatz zu den bekannten Cochaperonen keinen Einfluss auf den ATPase- Zyklus von mtHsp70. Allerdings aggregieren in Abwesenheit von Hep1 mitochondriale Hsp70-Proteine. Diese Aggregation ist irreversibel und führt zum Verlust der Funktion der mitochondrialen Hsp70-Proteine. Diese Beeinträchtigung führt wiederum zu Defekten in Prozessen, die funktionelle mitochondriale Hsp70-Proteine benötigen. So wurden in ∆hep1- Zellen Defekte im mitochondrialen Proteinimport und der Biogenese von Eisen-Schwefel- Clustern beobachtet. Aufgrund dieser Defekte zeigen ∆hep1-Zellen einen Temperatursensitiven Wachstumsphänotyp. Die Tendenz zur Aggregation ist spezifisch für mitochondriale Hsp70-Proteine, wobei besonders die nukleotidfreie Form von mtHsp70 betroffen ist. Im aggregierten Material ließ sich eine erhöhte Sensitivität der ATPase-Domäne gegenüber zugesetzter Protease feststellen, was auf eine Fehlfaltung dieser Domäne deutet. Es wurde eine Region in der ATPase- Domäne von mtHsp70 identifiziert, die zur Aggregation von mtHsp70 beiträgt. Durch Austausch dieser Region gegen die entsprechende Region aus DnaK, dem nächsten nicht mitochondrialen Verwandten von mtHsp70, konnte ein teilweise funktionsfähiges Hsp70- Protein hergestellt werden, dessen Löslichkeit nicht mehr von Hep1 abhängig ist. MtHsp70 aggregiert nur, wenn es sowohl die ATPase-Domäne als auch die PBD aufweist. Die Interdomänenkommunikation zwischen der ATPase-Domäne und der PBD von mtHsp70 scheint zur Ausbildung einer instabilen Konformation notwendig zu sein. Hep1 bindet an mtHsp70 in dieser Konformation und verhindert somit die Aggregation. Mit Hep1 wurde in dieser Arbeit ein neuer Typ von Interaktionspartnern mitochondrialer Hsp70-Proteine entdeckt. Es wirkt als Chaperon für dieses Hsp70-Proteine, indem es an sie bindet und deren Aggregation verhindert.

Proteins are central to all biological processes. To become functionally active, newly synthesized protein chains must fold into unique three-dimensional conformations. A group of proteins, known as molecular chaperones, are essential for protein folding to occur with high efficiency in cells. Their main role is to prevent off-pathway reactions during folding that lead to misfolding and aggregation. A number of human diseases are known to result from aberrant folding reactions. The formation of insoluble protein aggregates in neurons is a hallmark of neurodegenerative diseases including Huntington’s disease (HD). These disorders are though to result from the acquisition of dominant, toxic functions of misfolded proteins. HD is caused by a CAG trinucleotide expansion that results in the expansion of a polyglutamine (polyQ) tract in the protein Huntingtin (Htt). The disorder is characterized by a progressive loss of specific neurons and the formation of inclusions containing aggregated Htt. Aggregate formation is causally linked to the progressive HD neuropathology, though it is not clear whether large insoluble, fibrillar structures or smaller assemblies of Htt are the toxic agents. Toxicity could arise from the recruitment of other polyQ-containing proteins, i.e. transcription factors, into the inclusions resulting in a loss of their normal cellular functions. Here, soluble Htt oligomers have been found to accumulate in the nucleus and to inhibit the function of the transcription factors TBP and CBP in cells. Aberrant interaction of toxic Htt with the benign polyQ repeat of TBP structurally destabilized the transcription factor, independent of the formation of insoluble coaggregates and caused transcriptional dysregulation. Chaperones of the Hsp70 family protect against this deactivation by modulating the conformation of Htt. This protective effect of Hsp70 was found to be based on a cooperation between Hsp70 and the chaperonin TRiC. Both chaperone systems cooperate in eliminating toxic polyQ oligomers, which may resemble the potentially pathogenic, prefibrillar states of other amyloidogenic disease proteins, and in stabilizing mutant Htt in a soluble, oligomeric state that is not associated with toxicity. TRiC and Hsp70 appear to be part of an effective chaperone network preventing the formation of harmful, amyloidogenic proteins species. They act synergistically on Htt, reminiscent of their sequential action in assisting the folding of newly-synthesized proteins.

Extracellular proteome of Aeromonas hydrophila AH-1, Albumin and Hsp70 in corneal epithelial wound repair, Arginine-mediated protein expression in intestinal Caco-2 cells, 3D-LC-MS/MS proteomics

Extracellular proteome of Aeromonas hydrophila AH-1, Albumin and Hsp70 in corneal epithelial wound repair, Arginine-mediated protein expression in intestinal Caco-2 cells, 3D-LC-MS/MS proteomics

Import of a hybrid construct consisting of the transit sequence of SSU, the N-proximal part of mature Tic110 and the mature SSU into chloroplasts led to the appearance of a soluble stromal import intermediate and the proposal that Tic110 might use a re-export pathway from the stroma to the inner envelope membrane. For full length Tic110 no soluble intermediate has been observed yet. One of the goals of this work was to investigate the import pathway of Tic110 in more detail. In this research the soluble stromal intermediate of Tic110 was observed, its re-export to the membrane was followed, and finally, the intermediate was isolated and co-immunoprecipitated with the stromal chaperones Hsp93, Hsp70 and to a lesser extent Cpn60. The obtained results indicate that Tic110, as proposed, uses a re-export pathway (conservative sorting) during its import into the chloroplast inner envelope membrane. Tic110 also requires stromal chaperones for achieving its native conformation, prior to the insertion into the inner envelope membrane. The pathway for targeting to the intermembrane space of chloroplasts had not been intensively studied yet. For this reason, the analysis of two intermembrane space localized proteins was conducted: Tic22, a 22 kDa Tic-complex protein component, and MGD1, synthase of MGDG, the most abundant galactolipid in nature. Both proteins are nuclear-encoded and synthesized on cytosolic ribosomes with a cleavable N?terminal chloroplast targeting presequence. Tic22 was found to be associated with the outer face of the inner envelope membrane, as well as with the inner face of the outer envelope membrane, even though at a lower level. MGD1 was proposed to be associated with one of the envelopes by weak electrostatic interactions. Import properties of Tic22 and MGD1 and the localization of MGD1 were investigated in this research. Results presented in this thesis show that import of MGD1 is dependent on, and that of Tic22 is enhanced by, but not dependent on, addition of external ATP. Both preproteins need thermolysin sensitive components on the chloroplast surface for successful import. Chemical crosslinking and immunoprecipitation have demonstrated that Tic22 and MGD1 interact with the components of the Toc translocon of the chloroplast outer envelope during their translocation. Import competition experiments showed that both proteins use the Toc machinery of the general import pathway. Therefore, proteins targeted to the intermembrane space seem to use the same translocation mode across the outer envelope as stromal proteins.

We applied mass spectrometry based approach to explore the proteins differentially regulated by PML-RARalpha a translocation characteristic of acute promyelocytic leukemia (APL). Differentialy expressed proteins, a number of which are related to cell cycle function, including OP18, HSP70, GRP75 and Pin1 were identified by mass spectrometry. Further analysis of the OP18 pathway indicated that mRNA expression of OP18 was higher in APL patients and the increased OP18 protein expression upon PML-RAR induction was overcome by retinoic acid treatment. PML-RARalpha induced cell cycle progression and led to mitotic exit. RNA interference experiments revealed that siRNA against OP18 overcomes PML-RARalpha effects on cell cycle progression. In addition to increased OP18 expression by PML-RARalpha, 2D gel electrophoresis revealed an isomer of OP18, subsequently confirmed as Ser63 phosphomer to be downregulated by PML-RARalpha. Based on these findings, point mutation experiments indicated that decreased phosphorylation of Ser63 in OP18 is important for PML-RARalpha mediated cell cycle and mitotic index effects since constitutive phosphorylated mutant (Ser63-asp) of OP18 overcame the PML-RARalpha effects in U937-PR cells, NB4 and APL patients. In summary, our results demonstrate that the effect of PML-RAR on cell cycle progression and mitotic exit is via two mechanisms: increasing the expression of OP18 and decreasing the phosphorylation of OP18 at Ser63.

Die genetischen Grundlagen der chronisch-entzündlichen Darmerkrankungen M. Crohn und Colitis ulcerosa sind komplex und noch nicht in allen Einzelheiten aufgeklärt. Hitzeschockproteine (Hsp72) haben eine protektive Wirkung in entzündeter Darmmukosa. Daher könnte ein Mangel dieser Proteine den Verlauf inflammatorischer Darmerkrankungen beeinflussen. Zur Verifikation dieser Hypothese wurde die genomische DNA aus Leukozyten von 61 kaukasischen Patienten mit M. Crohn und 25 Patienten mit Colitis ulcerosa isoliert. Anschliessend wurde durch Polymerase-Kettenreaktion ein Segment des Hsp70-2 Gens amplifiziert, das einen A/G-Transitionspolymorphismus trägt (Allel B), der mit einer geringeren Hsp72-Expression assoziiert ist. Durch eine Restriktionsanalyse (Enzym: PstI) und konsekutiver Elektrophorese konnte das Vorliegen der Transition überprüft werden. Die aus den Krankenakten erhobenen Krankheitsverläufe (Alter bei Erstdiagnose, Ausdehnung und Lokalisation der Erkrankung, extraintestinale Manifestationen, Operationen, Komplikationen, Medikation) wurden mit den Ergebnissen der Genanalyse korreliert. Das Allel B kam bei Patienten mit M. Crohn nicht signifikant häufiger vor als bei gesunden Personen (44 % bei Patienten vs. 42 % bei Gesunden). Die Resultate zeigten jedoch eine signifikante Assoziation (p

Die Zusammensetzung und Arbeitsweise des Tic Komplexes ist noch ungeklärt. Tic110 ist die einzige von sieben Komponenten, die allgemein akzeptiert ist. Die Funktion und genaue Topologie des Proteins ist aber noch umstritten (Abb.3). Im Rahmen dieser Arbeit wurden verschiedene Experimente zur Klärung der Topologie und Funktion des Proteins durchgeführt. Zum Einen wurde über ein CD-Spektrum eine alpha-helikale Sekundärstruktur für Tic110 gezeigt. Proteasebehandlung sowohl von Vesikeln der inneren Hüllmembran als auch von intakten Chloroplasten lassen vermuten, dass Bereiche von Tic110 in den Intermembranraum zeigen. Auf der anderen Seite weisen Affinitätschromatographieversuche mit dem C-Terminus von Tic110 darauf hin, dass das Protein im Stroma mit HSP93 und HSP70 interagiert. Diese Ergebnisse lassen vermuten, dass ein Teil des C-Terminus in den Intermembranraum ragt und ein anderer Teil ins Stroma. Ob im C-Terminus amphiphile Helices ausgebildet werden können, muss geklärt werden. Mengenmäßig ist Tic110 prominenter in der inneren chloroplastidären Hüllmembran vorhanden als Tic20, der andere „Kandidat“ für die Pore des Tic Komplexes. Im Vergleich zur Menge von Toc75, der Pore der äusseren Hüllmembran, ist Tic110 in ähnlichen Mengen vorhanden. Tic110 ist also ein geeigneter Kandidat, an der Porenbildung beteiligt zu sein. Desweiteren wurden Interaktionspartner vom N-Terminus von Tic110 gesucht. Dabei wurde ein 32 kDa Protein gefunden, dass große Homologien zu sogenannten „short-chain“ Dehydrogenasen aufweist. In der vorliegenden Arbeit wurde über Importversuche und Immunpräzipitationsexperimente eine Zugehörigkeit des Proteins zum Tic Komplex gezeigt. Die Komponente wurde Tic32 genannt. Tic32 ist eine funktionelle Dehydrogenase, deren Beteiligung während des Importprozesses noch zu klären bleibt. T-DNA Insertionslinien von Tic32 ergaben, dass das Protein für die für die Plastidenentwicklung essentiell ist. Da mit Tic32 neben Tic55 und Tic62 nun schon die dritte Tic Komponente gefunden wurde, die Redox Charakteristika aufweist, wurden verschiedene Importexperimente durchgeführt. Dafür wurden zwei chloroplastidäre FNR-Isologe und zwei chloroplastidäre Fd-Isologe in Chloroplasten importiert, deren Redoxzustand vor der Importreaktion mit verschiedenen Metaboliten oder Redoxkomponenten beeinflusst wurde. Sowohl nach Behandlung der Chloroplasten mit HAR, deamino-NAD, Oxalacetat und Kaliumhexacyanoferrat nimmt die Importeffizienz der FNR L2 Form stark ab. Auch für die Ferredoxin-Isologe ließ sich ein unterschiedliches Importverhalten feststellen, wenn auch nicht so eindeutig wie für die FNR-Isologe. Dieser Regulationsmechanismus muß nun in weiteren Experimenten genauer untersucht werden.

A broad variety of tumor cells express Hsp70 on their cell surface. These tumor cells are more sensitive to the lysis mediated by NK cells. Here, it was shown that the 14mer peptide TKD (TKDNNLLGRFELSG, aa450-463) derived from the C-terminus of Hsp70 is the minimal sequence of Hsp70 that has the capacity to activate NK cells. NK cells incubated with low dose IL-2 (100 IU/ml) plus TKD (2 µg/ml) showed an enhanced proliferative capacity and an enhanced cytolytic activity and migratory capacity against Hsp70 membrane-positive tumor cells. Furterhmore, secretion of the cytokines IFN-g and TNF-a was enhanced. TKD stimulated NK cells also showed enhanced intracellular levels of the serine protease granzyme B. Since binding of fulllength Hsp70 protein and TKD to NK cells was specific and concentration-dependent, an involvement of a Hsp70 specific receptor was hypothesized. It was shown that the C-type lectine receptor CD94 is involved in Hsp70/TKD-NK cell interaction: (i) CD94 was upregulated in NK cells after incubation with Hsp70/TKD; (ii) binding of Hsp70 could be inhibited by a CD94 specific antibody; (iii) Hsp70 reactivity correlated with CD94 expression on NK cells; and (iv) Hsp70 reactivity of NK cells could be inhibited by a CD94 specific antibody. Finally, the mechanism of lysis of Hsp70 membrane-positive tumor cells by NK cells could be elucidated. It was shown that the serine protease granzyme B binds to Hsp70/TKD on the cell surface of Hsp70 membrane-positive tumor cells and is specifically taken up by these cells. As demonstrated by different apoptosis assays (Annexin V staining, cytochrome c release, and DAPI staining) granzyme B causes apoptosis specifically in Hsp70 membrane-positive tumor cells, but not in their Hsp70 membrane-negative counterparts.

Im Rahmen dieser Arbeit wurde an Hand dreier verschiedener Ansätze, die Bedeutung von HSP70 für die Stressreaktion der Bauchspeicheldrüse und den Schweregrad bei der akuten experimentellen Pankreatitis untersucht. Im Zentrum stand dabei die Frage, ob durch die verschiedenen gewählten Präkonditionierungsmodelle HSP70 induziert werden kann und welche Auswirkungen HSP70 auf die pankreatitisspezifischen Parameter, insbesondere der frühzeitigen intrazellulären Trypsinaktivierung hat. Von besonderem Interesse war zudem die hormonelle Präkonditionierung mit dem Atrial Natriuretischen Peptid zur Prävention vor einer Caerulein-induzierten Pankreatitis durch Induktion von HSP70. Weiterhin wurde die Bedeutung der Hyperthermie-Präkonditionierung an isolierten Azinuszellen eingehend studiert und schließlich durch die Generierung einer transgenen Maus versucht, die genaue Funktion von HSP70 bei der akuten experimentellen Pankreatitis aufzudecken. Am Modell frisch isolierter Azinuszellen wurde untersucht, ob und in welchem Ausmaß es durch eine Hyperthermie Präkonditionierung zu Veränderungen in der azinären Antwort auf eine CCK- Hyperstimulation kommt. Die Hyperthermie führt sowohl im Pankreas als auch in Azinuszellen zu einer verstärkten Expression von Hitzeschockproteinen, insbesondere von HSP70. Die Untersuchung des Effekts der Hyperthermie an isolierten Azinuszellen, die einer Hyperthermie Präkonditionierung unterzogen wurden, stellte sich als ein nicht prakti-kables Modell heraus, da die Zellen durch die vorangegangene Hyperthermie so in ihrer Funktionalität geschädigt waren, dass sie keine Reaktion mehr auf die Stimulation mit ver-schiedenen CCK- Konzentrationen zeigten. Die Kombination einer in vivo Hyperthermiebe-handlung von Ratten mit einem in vitro Modell der experimentellen Pankreatitis an frisch isolierten Azinuszellen, gewonnen aus den vorbehandelten Tieren, zeigte dann eine sehr deut-liche Reduktion der CCK- vermittelten intrazellulären Trypsinaktivierung. Dies spricht dafür, dass die Präkonditionierung und die darausfolgende gesteigerte HSP70 Expression eine Pro-tektion des Pankreas bewirkt und dadurch eine Reduktion der pathophysiologisch für die Ent-stehung der Pankreatitis bedeutsamen frühzeitigen intrazellulären Trypsinaktivierung hervor-ruft. Die hormonelle Präkonditionierung mit ANP hat sich als wirksamer Schutz vor Ischämie- Reperfusionsschäden in der isoliert perfundierten Rattenleber herausgestellt. Untersuchungen haben gezeigt, dass der protektiven Effekt von ANP über einen Anstieg des cGMP- Spiegels, eine Aktivierung des Hitzeschocktranskriptionsfaktors (HSF) und die dadurch hervorgerufene Expression von HSP70 zustande kommt. Pankreas- Azinuszellen weisen ANP- Rezeptoren auf und reagieren auf ANP mit einem Anstieg des cGMP- Spiegel. Deshalb wurde der Effekt der intravenösen ANP- Präkonditionierung untersucht, als mögliche Protektion des Pankreas vor einer Caerulein- induzierten Pankreatitis. Eine Gabe von ANP 20 Minuten vor der Induk-tion einer akuten Pankreatitis erwies sich aber als nicht protektiv. Dagegen konnte 24 h nach einer Präkonditionierung eine Induktion der HSP70 Expression und eine Protektion des Pank-reas vor einer experimentellen Pankreatitis beobachtet werden. Jedoch zeigte sich bei der Kontrollgruppe, die nur mit NaCl vorbehandelt wurde, der gleiche Effekt auf ANP. Dies lässt darauf schließen, dass Stress hervorgerufen durch die Anästhesie und die Katheterisierung der Jugularvene für eine Präkonditionierung und damit für eine Protektion ausreichend ist und damit ANP, im Gegensatz zum Modell des Ischämie-Reperfusionsschadens Leber, nicht für eine Präkonditionierung des Pankreas eingesetzt werden kann. Die Generierung einer transgenen Maus, zum definitiven Beweis des protektiven Potentials von HSP70, führte zwar zu einer Inkorporation des Transgens, aber zu keiner Expression von HSP70 auf Proteineben, so dass hier keine neuen Erkenntnisse gewonnen werden konnten.

The goal of this study was to investigate the function of the heat shock protein 70 family members, expressed in tumors under physiological and stress conditions and to dissect their role in tumor immune recognition as a function of intra- versus extracellular location. Another goal was to investigate whether heat-treatment at clinically relevant thermal doses affects the immunophenotype of a given tumor, as defined by tumor cell sensitivity to immune effector cells. For these questions, the human melanoma system was selected because it is well characterized with regards to tumor-associated antigens, like tyrosinase and Melan-A/MART-1, their epitopes and restriction elements for MHC class I presentation. In the first part of the study the focus specifically was on the time-temperature dependent effects of heat exposure. Two different thermal doses (41,8°C/120 minutes and 45°C/22 minutes) were selected that mimic the heterogeneity of the achieved temperature distribution within the tumor and the time-temperature dependent changes were determined in: a) antigen expression (tyrosinase and Melan-A/MART-1) at the protein and mRNA level; b) expression of the inducible HSP70 and the constitutive HSC70; c) processing and presentation of tyrosinase and MART-1 via MHC class I; d) susceptibility of melanoma cell lines to cytotoxic T lymphocytes like CD8+ T cells, LAK and NK cells. It was demonstrated that HSP70 and antigen expression display distinct expression and kinetics that reflect the thermohistory of the cells, i.e. exposure to high or low thermal doses. Immunologically, a low thermal dose did not alter immune recognition of the cells despite the fact that intracellular HSP70 and tyrosinase protein were upregulated. High thermal dose induced a pleiotropy of effects, including stronger upregulation of HSP70 and tyrosinase protein but downregulation of tyrosinase at mRNA level. Concordant with reduced HLA-A2 surface expression and tyrosinase mRNA levels, immune recognition of the heat-treated cells was initially reduced, but pretreatment levels were restored after 72 hours of recovery. The observation that tumor cells treated with temperatures below the breakpoint temperature maintain an immunological homeostasis during the heat shock response is of critical importance for the clinical application of hyperthermia in the treatment of tumors. In the second part of the study, the ability of HSP70 to cross-present a naturally expressed human tumor antigen, tyrosinase, that is of low immunigenicity, a situation that more closely resembles the patient situation was investigated. It was demonstrated that HSP70-peptide complexes (HSP70-PC) purified from tyrosinase-positive (HSP70-PC/tyr+) but not from tyrosinase-negative (HSP70-PC/tyr-) melanoma cells deliver the tyrosinase antigen to immature DCs for MHC class I restricted T cell recognition. T cell stimulation by HSP70-PC/tyr+ incubated with immature DCs with was very efficient even without additional DC maturation signals (e.g. exogenous TNF-?) demonstrating the ability of tumor-derived HSP70-PC to act as a chaperone for peptides and a signal for DC maturation. HSP70-PC in exerting both functions on DCs, delivering antigens and maturing DCs, ensures that the peptides that are delivered to the DCs are presented in an immunogenic context optimal for T cell stimulation. In conlusion, induction of intracellular heat shock proteins (HSPs) by heat does not interfere with the tumor immune recognition and when HSPs are expressed extracellularly they acquire immunostimulatory properties. These observations open new perspectives for the application of hyperthermia in combination with HSP-based vaccine in the treatment of solid tumors.

Myosine sind molekulare Motoren, die an einer Vielzahl von zellulären Prozessen wie Bewegung, Zellteilung oder Polarität beteiligt sind. Ihr Grundaufbau gliedert sich in Motordomäne, Hals- und Schwanzdomäne. Der Motor interagiert ATP-abhängig mit dem Aktinzytoskelett und ist die krafterzeugende Komponente. Vergleicht man die verschiedenen Myosine miteinander, zeigt der Kopfbereich die höchste Konservierung. An den Motor schliesst sich der Halsbereich an, der die Bindestellen für regulatorische Untereinheiten wie z.B. Calmodulin beinhaltet. Der Schwanzbereich dient zum einem der Interaktion mit der transportierten Fracht und zum anderen der Dimerisierung oder Organisation in Filamente. In der Hefe Saccharomyces cerevisiae findet man fünf Myosine aus drei verschiedenen Klassen. Myo1p ist das einzige Klasse II Myosinund gehört zu den muskelähnlichen Myosinen, die sich in Filamenten organisieren. Myo2p und Myo4p gehören zu den Klasse V Myosinen und vermitteln Prozesse wie Vesikel-Transport, mRNALokalisation und Vererbung von Organellen und Endoplasmatischen Retikulum. Es wird vermutet, dass sie Dimere bilden, die als prozessive Motoren, also eigenständig, durch die Zelle wandern und so ihre Fracht an den Ort ihrer Bestimmung bringen. Myo3p und Myo5p sind in ihrer Funktion redundant und vermitteln als Klasse I Myosine die Endozytose, sowie die Integrität und Polarität des kortikalen Aktinzytoskeletts. Sie liegen als Monomere vor und interagieren über spezifische Domänen in ihren Schwanzbereich mit einer Vielzahl von Proteinen wie z.B. Verprolin oder Komponenten des Arp2/3-Komplexes. Die rekombinante Expression von Myosinen stellt sich als sehr problematisch dar, da sich die Motordomäne nicht spontan in eine funktionelle Konformation falten kann. Verschiedene Publikationen deuten daraufhin, dass für die Faltung dieser Multidomänenstruktur die UCS-Proteine notwendig sind. UCS leitet sich von den Namen der zuerst identifizierten Mitglieder ab (UNC-45 aus C. elegans, Cro1p aus P. anserina und She4p aus S. cerevisiae), welche lediglich die C-terminale UCS-Domäne gemeinsam haben. Für UNC-45 konnte bereits gezeigt werden, das es über die UCS-Domäne mit der Motordomäne von Muskelmyosin interagiert und als Chaperon dessen thermale Aggregation verhindert. Ausserdem interagiert UNC-45 über eine N-terminale TPR-Domäne mit Hsp90 und über den zentralen Bereich mit Hsp70. Im Rahmen meiner Arbeit wurde der Einfluss von She4p auf die Funktion der Myosine untersucht. Es wurde gezeigt, dass She4p über die UCS-Domäne mit der Motordomäne von Klasse I und Klasse V Myosinen interagiertund somit die Lokalisation von Myo3p, Myo4p und Myo5p ermöglicht. Mit Hilfe eines Aktin Pelleting Assays konnte gezeigt werden, dass die Misslokalisation der Klasse I Myosine im she4! Hintergrund durch einen Defekt in der Aktinbindedomäne im Motorbereich verursacht wird. Die Spezifität von She4p für verschiedene Myosinklassen spiegelt sich in der zellulären Verteilung des Proteins wieder. Das UCS-Protein wird Myo2p-abhängig in die Knospenspitze transportiert, um dort die Interaktion zwischen Klasse I Myosinen und dem Aktinzytoskelett zu vermitteln. Im Gegensatz dazu benötigt Myo4p lediglich funktionelles She4p innerhalb der Zelle, da dieses Myosin durch Mutter- und Tochterzelle wandert und somit seinen Regulator überall benötigt. Die Tatsache, ob She4p wie UNC-45 als Chaperon an der Faltung der Motordomäne beteiligt ist, ist weiterhin unklar. Es konnte jedoch in einem Pulldown Experiment und einer Immunpräzipitation eine Interaktion zwischen She4p und Hsp90 festgestellt werden. Es ist daher durchaus möglich, dass She4p als Kochaperon das Hsp90 System zum Myosin rekrutiert, damit die Motordomäne in eine funktionelle Konformation gefaltet wird. Neben der zytoplasmatischen Funktion von She4p scheint es noch eine nukleäre zu geben, da im Pulldown Experiment zahlreiche Proteine gefunden wurden, die Teil des Processosomes der kleinen ribosomalen Untereinheit sind und im Nucleolus lokalisieren. Die Funktion von She4p in diesem Prozess ist noch unbekannt.

Mitochondrial heat shock protein 70 (mt-Hsp70) has been shown to play an important role in facilitating import into, as well as folding and assembly of nuclear-encoded proteins in the mitochondrial matrix. Here, we describe a role for mt-Hsp70 in chaperoning proteins encoded by mitochondrial DNA and synthesized within mitochondria. The availability of mt-Hsp70 function influences the pattern of proteins synthesized in mitochondria of yeast both in vivo and in vitro. In particular, we show that mt-Hsp70 acts in maintaining the var1 protein, the only mitochondrially encoded subunit of mitochondrial ribosomes, in an assembly competent state, especially under heat stress conditions. Furthermore, mt-Hsp70 helps to facilitate assembly of mitochondrially encoded subunits of the ATP synthase complex. By interacting with the ATP-ase 9 oligomer, mt-Hsp70 promotes assembly of ATP-ase 6, and thereby protects the latter protein from proteolytic degradation. Thus mt-Hsp70 by acting as a chaperone for proteins encoded by the mitochondrial DNA, has a critical role in the assembly of supra- molecular complexes.

The family of hsp70 (70 kilodalton heat shock protein) molecular chaperones plays an essential and diverse role in cellular physiology, Hsp70 proteins appear to elicit their effects by interacting with polypeptides that present domains which exhibit non-native conformations at distinct stages during their life in the cell. In this paper we review work pertaining to the functions of hsp70 proteins in chaperoning mitochondrial protein biogenesis. Hsp70 proteins function in protein synthesis, protein translocation across mitochondrial membranes, protein folding and finally the delivery of misfolded proteins to proteolytic enzymes in the mitochondrial matrix.

The role of ATP in the matrix for the import of precursor proteins into the various mitochondrial subcompartments was investigated by studying protein translocation at experimentally defined ATP levels. Proteins targeted to the matrix were neither imported or processed when matrix ATP was depleted. Import and processing of precytochrome b2, (pb2), a precursor carrying a bipartite presequence, into the intermembrane space was also strongly dependent on matrix ATP. Preproteins, consisting of 220 or more residues of pb2 fused to dihydrofolate reductase, showed the same requirement for matrix ATP, whereas the import of shorter fusion proteins (up to 167 residues of pb2) was largely independent of matrix ATP. For those intermembrane-space-targeted proteins that did need matrix ATP, the dependence could be relieved either by unfolding these proteins prior to import or by introducing a deletion into the mature portion of the protein thereby impairing the tight folding of the cytochrome b5 domain. These results suggest the following: (a) The import of matrix-targeted preproteins, in addition to a membrane potential ΔΨ, requires matrix ATP [most likely to facilitate reversible binding of mitochondrial heat-shock protein 70 (mt-Hsp70) to incoming precursors], for two steps, securing the presequence on the matrix side of the inner membrane and for the completion of translocation; (b) in the case of intermembrane-space-targeted precursors with bipartite signals, the function of ATP/mt-Hsp70 is not obligatory, as components of the intermembrane-space-sorting pathway may substitute for ATP/mt-Hsp70 function (however, if a tightly folded domain is present in the precursor, ATP/mt-Hsp70 is indispensable); (c) unfolding on the mitochondrial surface of tightly folded segments of preproteins is facilitated by matrix-ATP/mt-Hsp70.

We previously reported that hsp70 in the mitochondrial matrix (mt-hsp70 = Ssc1p) is required for import of precursor proteins destined for the matrix or intermembrane space. Here we show that mt-hsp70 is also needed for the import of mitochondrial inner membrane proteins. In particular, the precursor of ADP/ATP carrier that is known not to interact with hsp60 on its assembly pathway requires functional mt-hsp70 for import, suggesting a general role of mt-hsp70 in membrane translocation of precursors. Moreover, a precursor arrested in contact sites was specifically co-precipitated with antibodies directed against mt-hsp70. We conclude that mt-hsp70 is directly involved in the translocation of many, if not all, precursor proteins that are transported across the inner membrane.

Thu, 8 Nov 1990 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7582/1/Neupert_Walter_7582.pdf Pfanner, Nikolaus; Craig, Elisabeth A.; Neupert, Walter; Shilling, Jeffery; Ostermann, Joachim; Kang, Pil-Jung

Mon, 1 Jan 1990 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7574/1/7574.pdf Neupert, Walter; Langer, Thomas