Podcasts about h3k27

A new editorial paper was published in Oncotarget's Volume 14 on May 12, 2023, entitled, “Targeting H3K27me3 loss in pediatric brain tumors - a perspective on epigenetically guided cancer therapy.” High-grade tumors of the central nervous system, including medulloblastoma, ependymoma and DMG (diffuse midline glioma, formerly known as DIPG (diffuse intrinsic pontine glioma)), constitute a major challenge in pediatric oncology. They are characterized by an aggressive growth and high relapse rates and claim the lives of many pediatric cancer patients. Both medulloblastoma and ependymoma are treated with surgical resection followed by adjuvant radiation therapy. DMG, on the other hand, diffusely infiltrates the brain stem making a resection virtually impossible. Thus, radiotherapy is the primary treatment modality for this tumor. While radiation temporarily attenuates the progression of DMG this brain cancer remains incurable and most children succumb to their disease. In his new editorial, Dr. Michael Goldstein from Johns Hopkins University School of Medicine discusses the extensively investigated molecular profiles of the aforementioned pediatric brain tumors demonstrating distinct epigenetic traits. “Strikingly, a global loss of H3K27 tri-methylation (H3K27me3) as a result of the dominant-negative histone H3K27M mutation was found to be a hallmark of DMG occurring in the majority of the tumors.” H3K27me3 is a product of the EZH2 histone methyltransferase affecting multiple cellular processes including transcription, chromatin structure and DNA damage response. Similarly, the aggressive PFA ependymoma subgroup is characterized by a lack of H3K27me3 due to an overexpression of the EZHIP protein that acts as an EZH2 inhibitor whereas less aggressive PFB tumors retain normal H3K27me3 levels. However, no comprehensive analysis of H3K27me3 expression patterns in medulloblastoma has been performed and the significance of this epigenetic mark in pediatric brain tumors has remained unknown. “To address this, we have investigated the levels of the H3K27me3 histone mark and its role in treatment response of non-WNT/SHH medulloblastoma comprising group 3 and group 4 tumors. We demonstrated that about 50% of the tumors in patients with group 3 and group 4 medulloblastoma are H3K27me3 deficient. Strikingly, loss of H3K27me3 was associated with high relapse rates and poor survival.” DOI - https://doi.org/10.18632/oncotarget.28427 Correspondence to - Michael Goldstein - mgolds33@jhu.edu Sign up for free Altmetric alerts about this article - https://oncotarget.altmetric.com/details/email_updates?id=10.18632%2Foncotarget.28427 Subscribe for free publication alerts from Oncotarget - https://www.oncotarget.com/subscribe/ Keywords - cancer, epigenetics, brain tumor, EZH2, H3K27me3, radiation therapy 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. To learn more about Oncotarget, please visit https://www.oncotarget.com and connect with us: SoundCloud - https://soundcloud.com/oncotarget Facebook - https://www.facebook.com/Oncotarget/ Twitter - 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/ Media Contact MEDIA@IMPACTJOURNALS.COM 18009220957

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.01.518657v1?rss=1 Authors: He, X.-B., Guo, F., Zhang, W., Wu, Y., Le, W., Wang, H., Zhou, Q., Huang, H. Abstract: Regulation of dopamine (DA) biosynthesis is critical for the functionalities of midbrain DA neurons. Tyrosine hydroxylase (TH) is the rate-limiting enzyme for dopamine (DA) biosynthesis in midbrain DA neurons. Here we report that DA contents are decreased in the midbrain and striatum of DA neuron-specific JMJD3 conditional knockdown mice. Consistent results are obtained from mice underwent pharmaceutical JMJD3 inhibition. Biochemical and histological experiments reveal that TH mRNA and protein levels are specifically decreased in DA neurons residing in ventral tegmental area but not substantia nigra pars compacta. On behavioral level, JMJD3 knockdown affects inflammation-induced chronic mechanical hyperalgesia but not locomotor coordination, corresponding to DA-associated behavior in ventral tegmental area and in substantia nigra pars compacta, respectively. Mechanistically, using a midbrain DA neuron culture, we demonstrate that JMJD3 transactivates TH gene expression through direct binding onto TH promoter and catalyzing H3K27 de-methylation. In summary, our findings reveal a novel role of JMJD3 in adult midbrain DA system and suggest its functional specificity with DA subtype heterogeneity. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Aging-US published a Special Collection on Eye Disease which included "ALKBH5-mediated m6A demethylation of FOXM1 mRNA promotes progression of uveal melanoma" which reported that ALKBH5, a key component of the N6-methyladenosine (m6A) methyltransferase complex, was significantly elevated in uveal melanoma cell lines and inhibited tumor growth in vitro and in vivo. EP300-induced H3K27 acetylation activation activated increased ALkbH5 expression and inhibited UM cell proliferation, migration, invasion and increased apoptosis in vitro. Besides, it may promote UM metastasis by inducing epithelial-to-mesenchymal transition (EMT) via demethylation of FOXM1 mRNA, which increases its expression and stability. It is a potential prognostic biomarker and therapeutic target in UM. Dr. Jingxiang Zhong and Dr. Lian Liu said, "Uveal melanoma (UM), which originates from melanocytes, is the most common primary intraocular malignancy in adults." Up to 50% of patients with primary malignant meningitis (UM) will develop metastatic disease. The most common sites of UM metastasis are the liver (60.5%), lungs (24.4%), skin/soft tissue (10.9%), and bone (8.4%). Unfortunately, the 1-year survival rate of UM patients with metastases is only 15% [5]. There is a pressing need to find useful prognostic biomarkers and therapeutic targets for this disease. Alkhabh5 overexpression of ALKBH5 promotes EMT of UM by upregulating FOXM1 expression via demethylating the m6A modification and further increasing the stability of FOXm1 mRNA. The Zhong/Liu Research Team concluded in their Aging-US Research Output, "we demonstrate that ALKBH5, which is positively regulated by epigenetic modifications of H3K27 acetylation, promotes tumor progression by inducing tumor EMT and increasing FOXM1 expression via m6A demethylation (Figure 7). Therefore, ALKBH5 is a potential target of UM molecular therapy." Full Text - https://www.aging-us.com/article/202371/text Correspondence to: Jingxiang Zhong email: tzjx@jnu.edu.cn and Lian Liu email: lianliu@jnu.edu.cn Keywords: uveal melanoma, ALKBH5, FOXM1, senescence-associated T cells, m6A demethylation About Aging-US Launched in 2009, Aging-US publishes papers of general interest and biological significance in all fields of aging research as well as topics beyond traditional gerontology, including, but not limited to, cellular and molecular biology, human age-related diseases, pathology in model organisms, cancer, signal transduction pathways (e.g., p53, sirtuins, and PI-3K/AKT/mTOR among others), and approaches to modulating these signaling pathways. To learn more about Aging-US, please visit http://www.Aging-US.com or connect with @AgingJrnl Aging-US is published by Impact Journals, LLC please visit http://www.ImpactJournals.com or connect with @ImpactJrnls Media Contact 18009220957x105 MEDIA@IMPACTJOURNALS.COM

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.27.223438v1?rss=1 Authors: Kraft, K., Yost, K. E., Murphy, S., Magg, A., Long, Y., Corces, R. M., Granja, J. M., Mundlos, S., Cech, T. R., Boettiger, A., Chang, H. Y. Abstract: Polycomb-group proteins play critical roles in gene silencing through the deposition of histone H3 lysine 27 trimethylation (H3K27me3) and chromatin compaction. This process is essential for embryonic stem cell (ESCs) pluripotency, differentiation, and development. Polycomb repressive complex 2 (PRC2) can both read and write H3K27me3, enabling progressive spread of H3K27me3 on the linear genome. Long-range Polycomb-associated DNA contacts have also been described, but their regulation and role in gene silencing remains unclear. Here, we apply H3K27me3 HiChIP, a protein-directed chromosome conformation method, and optical reconstruction of chromatin architecture to profile long-range Polycomb-associated DNA loops that span tens to hundreds of megabases across multiple topological associated domains in mouse ESCs and human induced pluripotent stem cells. We find that H3K27me3 loop anchors are enriched for Polycomb nucleation points and coincide with key developmental genes, such as Hmx1, Wnt6 and Hoxa. Genetic deletion of H3K27me3 loop anchors revealed a coupling of Polycomb-associated genome architecture and H3K27me3 deposition evidenced by disruption of spatial contact between distant loci and altered H3K27me3 in cis, both locally and megabases away on the same chromosome. Further, we find that global alterations in PRC2 occupancy resulting from an EZH2 mutant selectively deficient in RNA binding is accompanied by loss of Polycomb-associated DNA looping. Together, these results suggest PRC2 acts as a "genomic wormhole", using RNA binding to enhance long range chromosome folding and H3K27me3 spreading. Additionally, developmental gene loci have novel roles in Polycomb spreading, emerging as important architectural elements of the epigenome. Copy rights belong to original authors. Visit the link for more info

Dr Carolyn Lam:                Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the Journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center in Duke National University of Singapore. Dr Greg Hundley:             And I'm Greg Hundley, also associate editor of Circulation and director of the Poly Heart Center at BCU Health in Richmond. Carolyn, we've got a really exciting interview to follow our coffee chat and it's evaluating individuals with low complexity congenital heart disease. We often think of those with high complexity congenital heart disease and looking at their cardiovascular events. We're going to hear a little bit about low complexity congenital heart disease.                                                 Now you've got a paper you wanted to talk about first. Dr Carolyn Lam:                Absolutely. You've got to hang on for that because I'm going to delve into chromatin architecture in heart failure, and it's in this paper from corresponding author Dr Foo from Genome Institute of Singapore.                                                 So, as background, the human genome actually folds in 3D to form thousands of chromatin loops within the nucleus encasing the genes and assists regulatory elements for accurate gene expression control. Now, these physical tethers of loops are anchored by the DNA binding protein CTCF, also known as the weaver of the genome and the cohesion ring complex. Now, the role of CTC in binding and changes in chromatin structure in heart failure are not well understood. Well, until today's paper.                                                 What the author said is they undertook an independent analysis of chromatin organization with mouse pressure overload model of myocardial stress or transverse aortic constriction, and a cardiomyocyte specific knockout of CTCF. So, interestingly, they found that the cardiac chromatin architectural in adult terminally differentiated cardiomyocytes was unchanged in pressure overload from transverse aortic constriction. Now this was completely unlike the CTCF knockout model where they verified that there was generation of vast genome-wide loss of genomic insulation and near complete abolition of the CTCF chromatin loops.                                                 Instead of chromatin rewiring on the scale of that knockout, the myocardial stress response appeared to proceed through enhancer H3K27 acetylation epigenetic changes and gene network co-regulation driven largely by fixed cardiac 3D chromatin architecture. In other words, a stable chromatin architecture really set the stage for accurate enhancer promoter interactions required for basal gene expression control and induction of the classical myocardial stress gene response. Dr Greg Hundley:             So Carolyn, are there therapeutic implications here for this? Dr Carolyn Lam:                Now of course, that was preclinical work, but it really opens the door to consider these epigenetic regulators that control disease expression changes and interacting gene sets in heart as potential future targets for novel heart failure therapy. Dr Greg Hundley:             Very interesting. So, I'm going to review and switch gears a little bit and focus on diabetic cardiomyopathy and mitochondria associated endoplasmic reticulin membranes. And this paper is from Shengnan Wu from the Center for Molecular and Translational Medicine at Georgia State University here in the US in Atlanta, Georgia. So as we all know, mitochondria are essential for cellular energy production, but when they're damaged, they become a major source of reactive oxygen species and pro-apoptotic factors. In particular, increasing evidence suggests that mitochondrial dysfunction is a central event in diabetic cardiomyopathy.                                                 Well, the mitochondria and the endoplasmic reticulum are key players that regulate many cellular functions and their structural and functional interactions are essential for cellular homeostasis. The contact points, however, through which the endoplasmic reticulum communicates with mitochondria, they're known as mitochondria associated endoplasmic reticulum membranes, or MAMS. Importantly, MAMS play a pivotal role in calcium signaling, lipid transport, energy metabolism and cell survival, and they've been implicated in a variety of diseases, including Alzheimer's Disease, cancer, lysosomal storage diseases, diabetes, obesity induced mitochondrial dysfunction and other metabolic disorders.                                                 But the role of these MAMS in the initiation and progression of Diabetic Cardiomyopathy is really unknown. So now, FUNDC1 is a highly conserved protein that's exclusively localized to the mitochondria. And this group had previously demonstrated that FUNDC1 was essential for maintaining the structure of MAMS and ensuring appropriate calcium transfer from the endoplasmic reticulum to the mitochondria normal hearts. Moreover, cardiac specific deletion of FUNDC1 induced cardiac dysfunction by inhibiting MAM formation. Dr Carolyn Lam:                Interesting. So that was their prior work? What did the current study show? Dr Greg Hundley:             Right, so what the investigator showed in this study is that high glucose driven inactivation of AMP-activated protein kinase increased FUNDC1 stability, but resulted in aberrant MAM formation, impaired mitochondrial calcium increase, mitochondria dysfunction and then cardiac dysfunction. And additionally, AMP-K activation reverses Diabetic Cardiomyopathy by suppressing high glucose induced MAM formation, mitochondrial calcium increase and mitochondrial dysfunction.                                                 And interestingly, Metformin, an AMP-K activator, used exclusively for Type 2 Diabetes, might be effective in treating Diabetic Cardiomyopathy in individuals with Type 1 Diabetes. So a very interesting mechanistic study providing some information of how MAMS, mitochondrial function and endoplasmic reticulum could be important in understanding how to prevent Diabetic Cardiomyopathy. Dr Carolyn Lam:                Indeed. And you know, that last note that you made on Type 1 Diabetes, also links very well with the next paper that I chose. Which really asks the question, in Type 1 Diabetes, what are the relative prognostic importance and optimal levels of risk factors for mortality and cardiovascular outcomes? And this comes from Dr Rawshani and colleagues from the Swedish National Diabetes register who studied more than 32,600 patients with Type 1 Diabetes in their national observational cohort study from the Swedish National Diabetes register, with a mean follow-up of 10.4 years and a mean duration of diabetes of 17.9 years.                                                 They found that the most important predictors for outcomes were HP-A1C, albuminuria, duration of diabetes, systolic blood pressure and low-density lipoprotein cholesterol, or LDL cholesterol. Now, the lower levels of HP-A1C, systolic blood pressure and LDL cholesterol than contemporary target levels were associated with lower risk for outcomes. Albuminuria was associated with a two to four times greater risk of cardiovascular disease and death. And each millimole increase of LDL cholesterol was associated with 35 to 50% higher risk for outcomes. Dr Greg Hundley:             Boy, Carolyn, those are interesting results. So, what do we take away from this in clinical management of patients? Dr Carolyn Lam:                The take home message is that in patients with Type 1 Diabetes, the strongest predictors for mortality and cardiovascular disease, with the exception of age, were mostly conventional and modifiable cardio-metabolic risk factors. And this in turn suggests that increased clinical focus on these risk factors, particularly in primary prevention, may result in the largest relative risk reduction for mortality and cardiovascular disease, even in Type 1 Diabetes. So, future clinical trials may be designed to test these findings. Dr Greg Hundley:             Very good. Well, Carolyn, my next paper, I'm going to talk about five year outcomes after off-pump versus on-pump coronary artery bypass grafting in those over the age of 75 years. And this paper comes from Anno Diegeler from Bad Neustadt in Germany. From June of 2008 to September of 2011, they evaluated a total of 2,539 patients that were 75 years or older, who had been randomly assigned to undergo off-pump or on-pump coronary artery bypass grafting across 12 centers in Germany.                                                 And the primary outcome was all cause mortality at five years, and the secondary outcome included a composite of death, myocardial infarction and repeat revascularization. What did they show in this study? Well, after a median follow up of five years, the hazard ratio for off-pump versus on-pump coronary artery bypass grafting was 1.03, confidence interval 0.81 to 1.19, no difference. The composite outcome of death, myocardial infarction and repeat revascularization, the same. Hazard ratio 1.03, confidence interval 0.89 to 1.18, P-value 0.7.                                                 So, first take-home message, no difference if you had your surgery off-pump or on-pump, if you're over the age of 75. Now, another outcome related to incomplete revascularization. And what was striking I this study is whether you underwent on-pump or off-pump bypass, if you were incompletely revascularized, that was associated with both the primary as well as the secondary outcomes. So, in elderly patients, in summary, greater than or equal to 75 years, the five year survival rates as well as the combined outcome of death, MI and repeat revascularization, was similar for on-pump versus off-pump CABG. And incomplete revascularization was associated with a lower five year survival rate, irrespective of the type of surgery that was performed. Dr Carolyn Lam:                Interesting. Beautifully summarized, Greg. Thank you. Dr Greg Hundley:             Absolutely. And let's head on to that featured article.                                                 Well, welcome everyone to the second half of our program. We are very excited today to have Dr James Priest, from Stanford University School of Medicine. And also our associate editor Gerald Greil from University of Texas Southwestern School of Medicine in Dallas. And we're going to be discussing the article, Substantial Cardiovascular Morbidity in Adults with Lower Complexity Cardiovascular Disease.                                                 So, James, first could you tell us a little bit about what constitutes low complexity congenital heart disease? And then a little bit about your study population, your design, and the results that you found with your study? Dr James Priest:                So, low complexity congenital heart disease really derives from definitions of congenital heart disease in adults that are grown up and have different complexity of lesions. And so high complexity congenital heart disease, you see things that, as people may remember, adult cardiologists may remember from their training. People remember from medical school, things like single ventricle disease, hypoplastic left heart, tetralogy of fallot, transposition of the great arteries. But, non-complex, so our low complexity disease, really constitutes a relatively simple malformation. Things like atrial septal defects, ventricular septal defects, patent ductus arteriosus. Things that are treatable with a single surgery.                                                 You close the hole, you ligate the vessels, you dilate the valve, and the patient is affectively cured. So relatively low complexity diseases that can be treated with typically, a single surgery or minimal interventions to restore completely, or essentially normal, cardiovascular physiology.                                                 So, the study was based upon a very large you know, volunteer data set, the UK Biobank. It comes from the United Kingdom where 500 thousand individuals enrolled, and from those individuals there is genetic information, medical histories dating back to the 1990s, self-reported history. A variety of functional and neuropsychiatric measures. And if you get a group of 500 thousand individuals from anywhere, there's going to be some congenital heart disease in there. And so, we looked to see what types of congenital heart disease were in there. And in fact, there was lower complexity individuals.                                                 And because I spent some time on the research side of things with my adult colleagues, the first thing we looked at were from the common adult cardiovascular outcomes, things people write about in Circulation all the time. Coronary artery disease, atrial fibrillation, heart failure. We know these things are problems in adults with complex cardiovascular disease, but nobody had really looked for the most part in adults with low complexity or non-complex disease. And we were surprised to see such high event rates for these common adult cardiovascular conditions. Dr Greg Hundley:             So, what type of events did you appreciate in the population in follow up? Dr James Priest:                So, we really appreciated about a two-fold rate of let's say, acute coronary syndrome relative to the general population. Up to almost 13 fold risk of atrial fibrillation and heart failure, relative to the general population. So, really substantial and very impactful event rates. Dr Greg Hundley:             Very good. And so, just a couple points of clarification. Do you think that the events you observed, were they related to the congenital heart disease, per se? Or could it have been a result from the surgical procedure to treat that heart disease? Dr James Priest:                So, that's a great question. I think, in some ways, that's the fundamental question that the paper leads to. So, we thought of it in two different ways. You know, one, were these events, and they're perioperative events, for individuals receiving some type of care for their congenital heart disease, during their adulthood? And we performed a sensitivity analysis where we basically looked at those events and then looked for events occurring within a year of adult interventions. And we saw no difference in those event rates. So, they weren't perioperative or postoperative events in adults receiving adult congenital heart disease care.                                                 The second part of the question is really more of an existential question in some ways. You know, is there some fundamental relationship between the care these people received as children? Or the genetic basis of congenital heart disease in the first place that is somehow put people at risk long term for adult cardiovascular disease, acquired adult cardiovascular disease? And I think there's indeed a lot of different ways to try and get at that question and explore that more, which we're currently working on. Dr Greg Hundley:             So, Gerald, I wanted to turn over to you now and, in your practice that encompasses those that are young adults that have this low complexity congenital heart disease, how do you manage them now? And how might the results of this study suggest, potentially, a different management strategy? Dr Gerald Greil:                 Usually these patients, they're kind of thought to be cured or only needed minimal follow up in the past. So, if you take a patient with a VSD, rarely during childhood, young adult or even kind of in 20s and 30s, you have any major difficulties. And as a pediatric cardiologist, you rarely experience any major follow up problems with these patients. I think, particularly in the US, and I work actually for more than 10 years in the UK, the problem in the US is how can you organize follow up in these patients?                                                 There're insurance issues, there're issues about moving into different areas, and since these patients were kind of labeled as being healthy and close to normal, they were lost for follow up, particularly in the US. I think this study raises some concerns, we should probably be more careful and cautious and follow these patients up kind of in a lifelong session. And take care of them. This is definitely something, which is a new finding, and what the cause is, how we are following up, that's the question. I guess it could be a good question for future studies. Dr Greg Hundley:             You mentioned future studies. Specifically, what type of future studies do you think we need to perform next? This shows us that the events are occurring, are we ready yet for randomized trials to perform prevention? Do we need studies that have more frequent observation? What are your thoughts there? And I'll get your answer and then we'll come back to James and get his thoughts on the same question. Dr Gerald Greil:                 Yeah, I think the major thing is we need close follow up of these patients. And it will be a combined effort between pediatric and specialized adult cardiologists, with a special interest in patients with congenital heart disease. Once again, coming back to it, a closer follow up is a little bit dependent on the medical system, which you have. If you take Canada and the UK, it may be easier in these patients are under close follow up. And this allows large multicenter studies, large data bases like UK Bio Bank are kind of exemplary. And we should try to get something similar within the US or in other countries.                                                 I think that's the lesson what we take from that, we need larger data bases, probably more granular than what we have right now. I mean, James probably can comment in a second about the shortcomings and what can be done better in the UK Bio Bank to allow more detailed conclusions than we have currently from his study. Dr Greg Hundley:             James? Dr James Priest:                I would agree with that. I think as a person who does not, clinically speaking, take care of adults with congenital heart disease, my colleagues and I, or I have the impression from my colleagues that for most of the time, in most of these patients in the Unites States adults who had VSD or ASD repair as a child, they were essentially said, oh, you're cured. And they perhaps had some follow up during childhood, but then were otherwise discharged to live the rest of their lives.                                                 And so, in many cases I'd say the first step before performing any studies is to simply identify who these patients are, and figure out you know, what their risk factors otherwise for cardiovascular disease might be. Now, that being said, I think that was one of the powerful things about the UK Bio Bank study is that there's a large population in which all these traditional cardiovascular risk factors you know, obesity, lipid levels, hypertension, smoking status, all these things were uniformly measured in both the individuals with congenital heart disease, the adults with congenital heart disease. And of course the control population.                                                 And so that allowed us to make some estimates about what proportion of disease was attributable to these traditional cardiovascular risk factors. And what was attributable to other factors related, potentially, to the congenital heart disease. But all those things being said, I think the first questions that I often to tend to receive about these studies from the pediatric cardiologists and the adult congenital heart disease doctors, reflects the sorts of data sets that we're used to looking at.                                                 Well, what sort of an intervention did this person have? Did they have a ventriculostomy? When did they receive their diagnosis and their repair? Details of the surgical care and the perioperative of course, are not available in this data set because it's not a particularly pediatric cardiology focused data set. It's a broad population based data set. And so the relationship specifically the details of their perioperative care and diagnosis are not able to be attained. And so we'll need larger data sets that include that information to fully start to develop those sorts of relationships over time. Dr Greg Hundley:             So, we want to thank our lead author, Dr James Priest from Stanford University School of Medicine, and our associate editor, Gerald Greil from the University of Texas Southwestern Medical School in Dallas. And reviewing this very interesting article on lower complexity cardiovascular disease and its association with an increased risk of cardiovascular events. And thank you both so much for clarifying. It sounds like an opportunity to collect more data through registries, et cetera, that we may need to expand around the world.                                                 Thank you everyone for listening to Circulation on the Run. Remember that's your back stage pass to our journal. And we'll see you next week.  

Background: Radiation-induced alterations in posttranslational histone modifications (PTMs) may affect the cellular response to radiation damage in the DNA. If not reverted appropriately, altered PTM patterns may cause long-term alterations in gene expression regulation and thus lead to cancer. It is therefore important to characterize radiation-induced alterations in PTM patterns and the factors affecting them. Methods: A lymphoblastoid cell line established from a normal donor was used to screen for alterations in methylation levels at H3K4, H3K9, H3K27, and H4K20, as well as acetylation at H3K9, H3K56, H4K5, and H4K16, by quantitative Western Blot analysis at 15 min, 1 h and 24 h after irradiation with 2 Gy and 10 Gy. The variability of alterations in acetylation marks was in addition investigated in a panel of lymphoblastoid cell lines with differing radiosensitivity established from lung cancer patients. Results: The screening procedure demonstrated consistent hypomethylation at H3K4me3 and hypoacetylation at all acetylation marks tested. In the panel of lymphoblastoid cell lines, however, a high degree of inter-individual variability became apparent. Radiosensitive cell lines showed more pronounced and longer lasting H4K16 hypoacetylation than radioresistant lines, which correlates with higher levels of residual gamma-H2AX foci after 24 h. Conclusion: So far, the factors affecting extent and duration of radiation-induced histone alterations are poorly defined. The present work hints at a high degree of inter-individual variability and a potential correlation of DNA damage repair capacity and alterations in PTM levels.

Im Zellkern einer jeden Zelle besteht eine gewisse Ordnung der darin vorhandenen DNA und Proteine. Diese Ordnung wird unter dem Begriff „Zellkernarchitektur“ zusammengefasst. In der vorliegenden Arbeit ging es um die nähere Betrachtung einiger Aspekte der Zellkernarchitektur. Diese Aspekte betrafen 1. die Anordnung von Genen, 2. die Anordnung von Chromatin mit Hilfe unterschiedlicher Histonmodifikationen und 3. die Anordnungen von Chromosomenabschnitten, die mit komplexen messenger RNA-Sonden hybridisiert werden. Im ersten Teil der vorliegenden Arbeit wurde mittels 3D FISH die dreidimensionale Positionierung von drei auf dem Chromosom 1 lokalisierten Genen in Zellkernen der Burkitt- Lymphom Zelllinie DG75 bestimmt. Diese Zelllinie wurde von Stefan Bohlander zur Verfügung gestellt und enthielt einen induzierbaren episomalen Vektor für das CALM-AF 10 Gen. Messungen der Genexpression, die in der Bohlander Gruppe mit Hilfe eines Affymetrix- Chips durchgeführt wurden, zeigten das die Induktion des Transgens zu genomweiten Veränderungen der Expressionsmuster hunderter Gene in dieser Zelllinie führten. Die für die 3D FISH Experimente ausgewählten Markergene zeigten nach der Induktion eine signifikant veränderte Expression. Dennoch änderte sich die radiale Positionierung dieser Gene, darunter versteht man die mehr innere oder mehr periphere Position der Gene, nicht. Dieses Ergebnis schien zuerst darauf hinzuweisen, dass die Transkriptionsstärke keine bedeutsamer Faktor im Hinblick auf die radiale Positionierung ist. Die Befunde der Affymetrix-Chip Analyse für diese Gene konnten jedoch in einer anschließende Untersuchungen der Genexpression mit Real-Time-PCR nicht bestätigt werden, obwohl der Vergleich von Affymetrix-Chip und Real- Time-PCR Daten insgesamt eine klare Korrelation zwischen den Datensätzen zeigte. Bei Diskrepanzen gehen wir davon aus, dass Real-Time-PCR die zuverlässigeren Ergebnisse liefert. Bei der hier durchgeführten Real-Time-PCR Untersuchung wurden auch die Expressionsstärken aller in einer Nachbarschaft von etwa 1 Mbp um die Markergene annotierten Gene ermittelt. Dieses Fenster wurde gewählt, weil Untersuchungen in der Arbeitsgruppe von Thomas Cremer und anderen Gruppen gezeigt haben, dass ~1 Mbp Chromatindomänen die Basisstruktur der Chromatinorganisation darstellen. Als Maß für die gesamte Genexpression einer Chromatindomäne wurde eine „Total Expression Strength“ (TES) berechnet. Dieser Wert basiert auf den Real-Time-PCR Werten der annotierten Gene und berücksichtigt auch die Länge der ungespleissten RNA, die von einem Gen transkribiert wird. Dabei zeigte sich, dass das Markergen in der Domäne mit dem höchsten TES Wert am weitesten innen im Zellkern lokalisiert ist. Dieser Befund unterstützt Befunde aus der wissenschaftlichen Literatur, dass die radiale Positionierung von individuellen Genen von Eigenschaften der lokalen Umgebung abhängt. Da sich die Nachbarschaft der untersuchten Markergene nicht nur im Hinblick auf die TES Werte sondern auch im Hinblick auf die Dichte der dort annotierten Gene und den GC-Gehalt unterscheidet, bleibt offen, welcher dieser Parameter als Prädiktor für die zu erwartende radiale Position individueller Gene eine entscheidende Rolle spielt. Möglich ist auch, dass alle Parameter zusammenwirken oder dass je nach den speziellen Umständen einer Untersuchung verschiedene Parameter die radiale Positionierung eines Gens bevorzugt beeinflussen. Die Stabilität der radialen Positionierung der Markergene trotz einer genomweiten Veränderung des Genexpressionsmusters nach CALM-AF 10 Induktion stimmt mit Befunden verschiedener Arbeitsgruppe überein, die für einen hohen Grad an räumlicher Stabilität der Chromatinanordnung während der Interphase sprechen; ~1 Mbp Chromatindomänen zeigen dementsprechend meist nur sehr begrenzte lokale Bewergungen (

Cellular gene regulation depends on fundamental epigenetic mechanisms, but epigenetic modifications also govern the regulation of the life cycle of Epstein-Barr virus (EBV). Promoter usage during latency depends on DNA methylation of the viral genome and CpG-methylation of certain promoters with meZREs is an indispensable prerequisite to switch from the latent to the lytic phase. In my thesis, I wanted to assess the underlying epigenetic principles of EBV’s gene regulation during the establishment of latency and upon lytic reactivation. My results suggested a new classification of viral promoters and phases of gene regulation that depend on the epigenetic state of the viral chromatin. According to this new model, EBV’s infectious cycle consists of an initial abortive lytic, a latent, and a productive lytic phase, and the viral promoters can be classified into default-on, poised-on, and poised-off promoters. Default-on promoters are immediately active upon infection of primary B cells leading to the so-called abortive lytic phase of an EBV infection. Default-on promoters encounter the cell in an environment that supports binding of the basal transcription machinery to activate viral gene transcription. Default-on promoters include the promoters of BALF1, BHRF1, BZLF1, BRLF1, BNLF2a, BCRF1, and Wp. The protein products are indispensible for the permanent establishment of EBV’s genome in latently infected cells supporting growth transformation, immune evasion, and anti-apoptotic cellular pathways. Default-on promoters are epigenetically silenced upon occupancy of EBV’s DNA with nucleosomes very early after infection and a switch to poised-on promoters is initiated. Poised-on promoters embody an epigenetically active state upon infection, but their activation requires an additional, virus-encoded factor to allow initiation of transcription. Wp-induced expression of EBNA1 promotes the switch to the poised-on promoter Cp to sustain long-term EBNA expression. Other poised-on genes including the viral structural proteins are not provided with their cofactor initially. During latency, these promoters are repressed through compaction of chromatin by high nucleosome occupancy, trimethylation of H3K27, and a stable transmission of repressive modifications by Polycomb-mediated long-term silencing. The establishment of a defined DNA methylation pattern on EBV’s DNA further represses poised-on promoters. DNA methylation is a prerequisite for the activation of a third promoter class, termed default-off promoters. Default-off promoters are bound and transactivated by BZLF1 in a methylation-dependent manner. Upon infection of primary B cells, EBV’s DNA is completely unmethylated, impeding an early expression of default-off genes. Only two to three weeks post infection the viral genome has acquired a proper epigenetic configuration that supports transcription of default-off genes. Binding of BZLF1 alone does not suffice to recruit the cellular transcription machinery including RNA polymerase II, but the chromatin requires remodeling, including a loss of nucleosomes and repressive modifications at default-off promoter sites. Default-off genes encode the viral lytic DNA replication machinery. The newly synthesized DNA templates lack epigenetic modifications because lytic DNA amplification is uncoupled from cellular DNA replication, eliminating the epigenetic maintenance mechanisms during the synthesis of viral progeny. As a consequence, default-on promoters and silenced poised-on promoters, which rely on unmethylated, epigenetically naïve templates, become also activated in the onset of the lytic phase. Silenced poised-on promoters require additionally a viral cofactor for their activation. This so-far unknown factor is probably provided upon lytic DNA amplification allowing the transcription of genes encoding for structural proteins that are necessary for the packaging of viral progeny. The released EBV progeny is epigenetically unmodified and ready to infect other cells. In essence, the regulation of EBV’s life cycle by epigenetic mechanisms is a paradigm for viral coevolution with its host. Repressive epigenetic modifications are common cellular defense mechanism to fight invading pathogens. EBV has hijacked this system for the regulation of promoter usage during its own life cycle, which has become a key principle of EBV’s success in infecting and persisting in its host.