Cellular process
POPULARITY
7 episodes with Endocytosis
2 episodes with Endocytosis
9 episodes with Endocytosis
3 episodes with Endocytosis
4 episodes with Endocytosis
9 episodes with Endocytosis
4 episodes with Endocytosis
4 episodes with Endocytosis
For the past 60 years the medical community has obsessively focused on lowering LDL-cholesterol levels… Research shows these five preventable health conditions make LDL-Cholesterol more likely to cause artery plaque build-up, even if your LDL-Cholesterol levels are low. Sponsored: Crush your Workouts and stay hydrated this summer with the Electrolyte + Creatine Combo by MYOXCIENCE: https://bit.ly/electrolyte-stix *Save with code podcast at checkout Link to Video and Show Notes: https://bit.ly/3WfpI5R Research Mentioned: Zanoni, P., Velagapudi, S., Yalcinkaya, M., Rohrer, L. & Eckardstein, A. von. Endocytosis of lipoproteins. Atherosclerosis 275, 273–295 (2018). Ference, B. A., Braunwald, E. & Catapano, A. L. The LDL cumulative exposure hypothesis: evidence and practical applications. Nat. Rev. Cardiol. 1–16 (2024) doi:10.1038/s41569-024-01039-5. Time Stamps: 00:45 LDL's link with atherosclerosis is nuanced. 02:30 Initial damage to the arterial wall makes LDL levels problematic. 03:45 Increases risk of arterial wall damage: elevated blood pressure, insulin resistance/diabetes, smoking/vaping, obesity, elevated blood viscosity, consuming oxidizableoils. 08:40 High LDL and high triglycerides suggest insulin resistance and increased cardiovascular risk. 09:50 Start with diet and exercise together. 11:20 Statins have concerning side effects. 13:15 Plaque formation begins early in life. 13:50 High LDL is found in centenarians. 14:44 Centenarians are metabolically healthy. 15:40 Your liver makes LDL cholesterol. 16:10 Every cell in your body requires cholesterol. 18:00 Diets high in seed oils make your LDL more likely to be oxidized. 20:55 30-50% of people who have heart attacks have optimal serum cholesterol.
Researchers define a nanopipette fabrication protocol for high resolution cell imagingTranscript of this podcastHello and welcome to the NanoLSI podcast. Thank you for joining us today. In this episode we feature the latest research by Yasufumi Takahashi at the Kanazawa University NanoLSI.The research described in this podcast was published in Analytical Chemistry in August 2023 Kanazawa University NanoLSI websitehttps://nanolsi.kanazawa-u.ac.jp/en/Researchers define a nanopipette fabrication protocol for high resolution cell imagingResearchers at Kanazawa University report in Analytical Chemistry how to produce nanopipettes that reliably provide nanoscale resolution scanning ion conductance microscopy images of living cells.A nanoscale view of living cells can provide valuable insights into cell structure and function. Over the years, various microscopy techniques have been enrolled to obtain a window into biological specimens at the nanoscale but all with their limitations and challenges. Although scanning ion conductance microscopy has demonstrated the capability to image living biological samples in solution with nanoscale resolution, it has been hampered by challenges in reliably producing nanopipettes with the optimum geometry for the job. Now researchers led by Yasufumi Takahashi at Kanazawa University's Nano LSI and Nagoya University have devised a protocol for reproducibly fabricating nanopipettes with the preferred geometry for high quality imaging. So what is scanning ion conductance microscopy and what kind of nanopipette does it need?Scanning ion conductance microscopy uses a nanopipette to control the distance between nanopipette and sample using an ion current as feedback signal. The shape of the nanopipette significantly influences the performance of the device. For instance, a wide aperture limits the possible resolution, a long shunt can lead to rectification effects that warp the ion current measurements, and if the glass of the nanopipette is too thick it can deform the sample before the proximity of the aperture has reached the point needed for constant ion current topographical mapping. As a result, the ideal nanopipette has a short shunt, small aperture and thin glass walls.The standard procedure for fabricating the nanopipette is to pull a capillary tube with a laser puller that heats the capillary tube it is manipulating. The capillary then narrows where it lengthens until it is finally drawn into two separate pieces. Although quartz can allow a little more control in the process of drawing the capillary tube into shape it is hydrophobic, which raises complications in actually filling the nanopipette with the aqueous solution needed for the ion current. For this reason, the researchers developed a protocol by which they could draw nanopipettes from borosilicate glass capillaries with the required control and reproducibility.Takahashi and his collaborators noted that ideally the starting capillary should have thick walls and a narrow inner diameter, however it is not easy to obtain capillary tubes to these requirements from commercial suppliers. Instead, they preheat the capillary for 5 s without pulling it, which causes the glass walls to the thicken and reduces the inner diameter. They also optimized the parameters for pulling the tube, such as the velocity.So did it work? Apparently soThe researchers demonstrated the performance of the nanopipettes they produced by imaging a cell undergoing a type of endocytosis, where it engulfs and absorbs some external material. They were able to image the microvilli – that is, tiny cellular membrane protrusions – found on the cell surface, as well as the endocytic pits that NanoLSI Podcast website
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.08.01.551580v1?rss=1 Authors: Mahapatra, S., Takahashi, T. Abstract: After exocytosis, release sites are cleared of vesicular residues to be replenished with transmitter-filled vesicles. Endocytic and scaffold proteins are thought to underlie this mechanism. However, physiological significance of the site-clearance mechanism among diverse central synapses remains unknown. Here, we tested this using action-potential evoked EPSCs in mouse brainstem and hippocampal slices in physiologically optimized condition. Pharmacological block of endocytosis enhanced synaptic depression at brainstem calyceal fast synapses, whereas it attenuated synaptic facilitation at hippocampal CA1 slow synapses. Block of scaffold protein activity likewise enhanced synaptic depression at calyceal synapses but had no effect at hippocampal synapses. At calyceal synapses, enhancement of synaptic depression by blocking endocytosis or scaffold activity occurred at nearly identical time courses with a time constant of several milliseconds starting immediately after the stimulation onset. Neither endocytic nor scaffold inhibitors prolonged the recovery from short-term depression. We conclude that endocytic release-site clearance can be a universal phenomenon supporting vesicle replenishment across fast and slow synapses, whereas presynaptic scaffold mechanism likely plays a specialized role in vesicle replenishment predominantly at fast synapses. 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/2023.07.12.548725v1?rss=1 Authors: Song, A., Phandthong, R., Talbot, P. Abstract: Both spill over and spill back of SARS-CoV-2 virus have been reported on mink farms in Europe and the United States. Zoonosis is a public health concern as dangerous mutated forms of the virus could be introduced into the human population through spillback. The purpose of our study was to determine the SARS-CoV-2 entry mechanism using mink lung epithelial cell line (Mv1Lu) and to block entry with drug inhibitors. Mv1Lu cells were susceptible to SARS-CoV-2 viral pseudoparticle infection, validating them as a suitable disease model for COVID-19. Inhibitors of TMPRSS2 and of endocytosis, two pathways of viral entry, were tested to identify those that blocked infection. Dyngo4a, a small molecule endocytosis inhibitor, significantly reduced infection, while TMPRSS2 inhibitors had minimal impact, supporting the conclusion that the entry of the SARS-CoV-2 virus into Mv1Lu cells occurs primarily through endocytosis. The small molecule inhibitors that were effective in this study could potentially be used therapeutically to prevent SARS-CoV-2 infection in mink populations. This study will facilitate the development of therapeutics to prevent zoonotic transmission of SARS-CoV-2 variants to other animals, including humans. 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/2023.07.10.548473v1?rss=1 Authors: Singh, S. B., Rajput, S. S., Sharma, A., Ananthanarayanan, V., Nandi, A., Patil, S. P. V., majumdar, a., Subramanyam, D. Abstract: Protein aggregation is a common underlying feature of neurodegenerative disorders. Cells expressing neurodegeneration associated mutant proteins show altered uptake of ligands, suggestive of impaired endocytosis, in a manner as yet unknown. Using live cell imaging, we show that clathrin mediated endocytosis (CME) is affected due to altered actin cytoskeletal organization in the presence of Huntingtin aggregates. Additionally, we find that cells containing Huntingtin aggregates are stiffer and less viscous than their wild type counterparts due to altered actin conformation, and not merely due to the physical presence of aggregate(s). We further demonstrate that CME and cellular viscosity can be rescued by overexpressing Hip1, Arp2/3 or transient LatrunculinA treatment. Examination of other pathogenic aggregates revealed that only a subset of these display defective CME, along with altered actin organization and increased stiffness. Together, our results point to an intimate connection between functional CME, actin organization and cellular stiffness in the context of neurodegeneration. 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/2023.04.29.538819v1?rss=1 Authors: Woodard, T. K., Rioux, D. J., Prosser, D. C. Abstract: Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC
Listen to a blog summary of an editorial perspective that was published in Oncotarget's Volume 14, entitled, “EGFR endocytosis: more than meets the eye.” _________________________________ EGFR (epidermal growth factor receptor) is a crucial protein that plays a significant role in various biological processes such as cell growth, proliferation, differentiation, and survival. Dysregulation of EGFR signaling has been implicated in the development and progression of numerous human cancers, including lung, breast and colon cancer. Therefore, EGFR has emerged as an attractive target for cancer therapy, and several drugs that target EGFR are in clinical use or under investigation. In recent years, endocytosis, the process by which cells internalize molecules and transport them into intracellular compartments, has emerged as a critical modulator of EGFR signaling. Endocytosis of EGFR not only regulates the duration and intensity of EGFR signaling but also modulates the signaling output. Dysregulation of EGFR endocytosis has been implicated in the development of drug resistance to EGFR-targeted therapies, highlighting the importance of understanding the mechanisms that regulate EGFR endocytosis. In a new editorial perspective, researchers Aysegul Sapmaz and Ayse Elif Erson-Bensan from Middle East Technical University provide an overview of the recent advances in our understanding of EGFR endocytosis and its role in EGFR signaling and cancer. The authors highlight the importance of the dynamic interplay between EGFR endocytosis and downstream signaling pathways and discuss how aberrant EGFR endocytosis contributes to drug resistance to EGFR-targeted therapies. On April 10, 2023, their editorial perspective was published in Oncotarget's Volume 14, entitled, “EGFR endocytosis: more than meets the eye.” “Here we review the role of the EGF-SNX3-EGFR axis in breast cancers with an extended discussion on deregulated EGFR endocytosis in cancer.” Full blog - https://www.oncotarget.org/2023/04/27/defining-the-complexity-of-egfr-endocytosis-in-cancer/ Paper DOI - https://doi.org/10.18632/oncotarget.28400 Correspondence to - Ayse Elif Erson-Bensan - erson@metu.edu.tr Sign up for free Altmetric alerts about this article - https://oncotarget.altmetric.com/details/email_updates?id=10.18632%2Foncotarget.28400 Subscribe for free publication alerts from Oncotarget - https://www.oncotarget.com/subscribe/ Keywords - EGFR, SNX3, USP32, endocytosis, cancer, breast cancer About Oncotarget Oncotarget is a primarily oncology-focused, peer-reviewed, open access journal. Papers are published continuously within yearly volumes in their final and complete form, and then quickly released to Pubmed. On September 15, 2022, Oncotarget was accepted again for indexing by MEDLINE. Oncotarget is now indexed by Medline/PubMed and PMC/PubMed. 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/2023.04.27.538587v1?rss=1 Authors: Toth, A. D., Szalai, B., Kovacs, O. T., Garger, D., Prokop, S., Balla, A., Inoue, A., Varnai, P., Turu, G., Hunyady, L. Abstract: The varying efficacy of biased and balanced agonists is generally explained by the stabilization of different active receptor conformations. In this study, systematic profiling of transducer activation of AT1 angiotensin receptor agonists revealed that the extent and kinetics of {beta}-arrestin binding exhibit substantial ligand-dependent differences, which however completely disappear upon the inhibition of receptor internalization. Even weak partial agonists for the {beta}-arrestin pathway acted as full or near full agonists, if receptor endocytosis was prevented, indicating that receptor conformation is not an exclusive determinant of {beta}-arrestin recruitment. The ligand-dependent variance in {beta}-arrestin translocation at endosomes was much larger than it was at the plasma membrane, showing that ligand efficacy in the {beta}-arrestin pathway is spatiotemporally determined. Experimental investigations and mathematical modeling demonstrated how multiple factors concurrently shape the effects of agonists on endosomal receptor-{beta}-arrestin binding and thus determine the extent of bias. Among others, ligand dissociation rate and G protein activity have particularly strong impact on receptor-{beta}-arrestin interaction, and their effects are integrated at endosomes. Our results highlight that endocytosis forms a key spatiotemporal platform for biased GPCR signaling and can aid the development of more efficacious functionally-selective compounds. 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/2023.02.15.528749v1?rss=1 Authors: Maxson, M. E., Huynh, K., Grinstein, S. Abstract: While it has been known for decades that luminal acidification is required for normal traffic along the endocytic pathway, the precise underlying mechanism(s) remain unknown. We found that dissipation of the endomembrane pH gradient resulted in acute formation of large Rab5- or Rab7-positive vacuoles. Vacuole formation was associated with and required hyperactivation of the Rabs, which was attributable to impaired GTPase activity, despite normal recruitment of cognate GAPs. Surprisingly, LRRK2 -a kinase linked to Parkinsons disease-was recruited to endomembranes and markedly activated upon dissipation of luminal acidification. LRRK2 phosphorylated Rab GTPases, rendering them insensitive to deactivation. Importantly, genetic deletion of LRRK2 prevented the {Delta}pH-induced vacuolation, implying that the kinase is required to modulate vesicular traffic. We propose that by dictating the state of activation of LRRK2 and in turn that of Rab GTPases, the development of a progressive luminal acidification serves as a timing device to control endocytic maturation. 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/2022.12.31.522383v1?rss=1 Authors: Matsubayashi, H. T., Mountain, J., Yao, T., Peterson, A. F., Deb Roy, A., Inoue, T. Abstract: Class IA phosphoinositide 3-kinase (PI3K) galvanizes fundamental cellular processes such as migration, proliferation, and differentiation. To enable multifaceted roles, the catalytic subunit p110 utilizes a multi-domain, regulatory subunit p85 through its inter SH2 domain (iSH2). In cell migration, their product PI(3,4,5)P3 generates locomotive activity. While non-catalytic roles are also implicated, underlying mechanisms and its relationship to PI(3,4,5)P3 signaling remain elusive. Here, we report that a disordered region of iSH2 contains previously uncharacterized AP-2 binding motifs which can trigger clathrin and dynamin-mediated endocytosis independent of PI3K catalytic activity. The AP-2 binding motif mutants of p85 aberrantly accumulate at focal adhesions and upregulate both velocity and persistency in fibroblast migration. We thus propose the dual functionality of PI3K in the control of cell motility, catalytic and non-catalytic, arising distinctly from juxtaposed regions within iSH2. 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/2022.12.08.519265v1?rss=1 Authors: Weinelt, N., Waechtershaeuser, K. N., Smith, S., Andrieux, G., Das, T., Jeiler, B., Roedig, J., Feist, L., Rotter, B., Boerries, M., Pampaloni, F., van Wijk, S. J. L. Abstract: Plasma membrane accumulation of phosphorylated mixed lineage kinase domain-like (MLKL) is a hallmark of necroptosis, leading to membrane rupture and inflammatory cell death. Pro-death functions of MLKL are tightly controlled by several checkpoints, including phosphorylation. Endocytosis and exocytosis limit MLKL membrane accumulation and counteract necroptosis, but the exact mechanisms remain poorly understood. Here, we identify linear ubiquitin chain assembly complex (LUBAC)-mediated M1 poly-ubiquitination (poly-Ub) as novel checkpoint for necroptosis regulation downstream of activated MLKL in human cells. Loss of LUBAC activity inhibits necroptosis, without affecting necroptotic signaling, but by preventing membrane accumulation of activated MLKL. Flotillin-1/2 act as putative necroptotic M1 poly-Ub targets that inhibit necroptosis suppression induced by LUBAC inhibition. Finally, we confirm LUBAC-dependent suppression of necroptosis in primary human pancreatic organoids. Our findings identify LUBAC as species-specific regulator of necroptosis which prevents MLKL membrane accumulation and pioneer primary human organoids to model necroptosis in near-physiological settings. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC
References Respir Res. 2017 Sep 6;18(1):168 Front Behav Neurosci. 2020; 14: 24 JLR Methods| 2020.Volume 61, ISSUE 11, P1512-1523, November 01 --- Send in a voice message: https://anchor.fm/dr-daniel-j-guerra/message
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.11.25.517735v1?rss=1 Authors: Mousavi, S. I., Lacy, M. M., Li, X., Berro, J. Abstract: The actin cytoskeleton is central to force production in numerous cellular processes in eukaryotic cells. During clathrin-mediated endocytosis (CME), a dynamic actin meshwork is required to deform the membrane against high membrane tension or turgor pressure. Previous experimental work from our lab showed that several endocytic proteins, including actin and actin-interacting proteins, turn over several times during the formation of a vesicle during CME in yeast and their dwell-time distributions were reminiscent of Gamma distributions with a peak around 1 s (Lacy et al., 2019). However, the distribution for the filament crosslinking protein fimbrin contains a second peak around 0.5 s. To better understand the nature of these dwell-time distributions, here we developed a stochastic model for the dynamics of actin and its binding partners. Our model demonstrates that very fast actin filament disassembly is necessary to reproduce experimental dwell-time distributions. Our model also predicts that actin-binding proteins bind rapidly to nascent filaments and filaments are fully decorated. Last, our model predicts that fimbrin detachment from actin endocytic structures is mechanosensitive to explain the extra peak observed in the dwell-time distribution. 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/2022.11.21.517438v1?rss=1 Authors: Yu, Y., Ozaki, T., Yoshimura, S. H. Abstract: Clathrin-mediated endocytosis plays a pivotal role in signal transduction pathways between the extracellular environment and the intracellular space. Accumulating evidence from live-cell imaging and super-resolution microscopy of mammalian cells suggests an asymmetric distribution of actin fibers near the clathrin-coated pit, which induces asymmetric pit-closing, rather than radial constriction. However, detailed molecular mechanisms of this asymmetricity remain elusive. Herein, we used high-speed atomic force microscopy to demonstrate that CIP4, a multidomain protein with a classic F-BAR domain and intrinsically disordered regions, is necessary for asymmetric pit-closing. Strong self-assembly of CIP4 via intrinsically disordered regions, together with stereospecific interactions with the curved membrane and actin-regulating proteins, generates a small actin-rich environment near the pit, which deforms the membrane and closes the pit. Our results provide a mechanistic insight into how spatio-temporal actin polymerization near the plasma membrane is promoted by a collaboration of disordered and structured domains. 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/2022.11.09.515770v1?rss=1 Authors: FREAL, A., Jamann, N., Ten Bos, J., Jansen, J., Petersen, N., Ligthart, T., Hoogenraad, C., Kole, M. H. P. Abstract: Activity-dependent plasticity of the axon initial segment (AIS) endows neurons with the ability to adapt action potential output to changes in network activity. Action potential initiation at the AIS highly depends on the clustering of voltage-gated sodium channels, however the molecular mechanisms regulating their plasticity remain largely unknown. Here, we used novel genetic tools to endogenously label sodium channels and their scaffolding protein, to reveal their nanoscale organization and longitudinally image AIS plasticity in hippocampal neurons, in slices and primary cultures. We find that induction of NMDA receptor-mediated long-term synaptic depression is linked to a rapid and local endocytosis of sodium channels from the distal AIS. These data reveal a novel fundamental mechanism for rapid activity-dependent AIS reorganization sharing conserved features with synaptic plasticity. 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/2022.10.03.510587v1?rss=1 Authors: Ramgoolam, K. H., Dolphin, A. C. Abstract: The N-type calcium channel, CaV2.2 is key to neurotransmission from the primary afferent terminals of dorsal root ganglion (DRG) neurons to their post-synaptic targets in the spinal cord. In this study we have utilized CaV2.2_HA knock-in mice, because the exofacial epitope tag in CaV2.2_HA enables accurate detection and localization of endogenous CaV2.2. CaV2.2_HA knock-in mice were used as a source of DRGs to exclusively study the presynaptic expression of N-type calcium channels in co-cultures between DRG neurons and wild-type spinal cord neurons. CaV2.2_HA is strongly expressed on the cell surface, particularly in TRPV1-positive small and medium DRG neurons. Super-resolution images of the presynaptic terminals revealed an increase in CaV2.2_HA expression and increased association with the post-synaptic marker Homer over time in vitro. Brief application of the TRPV1 agonist, capsaicin, resulted in a significant down-regulation of cell surface CaV2.2_HA expression in DRG neuron somata. At their presynaptic terminals, capsaicin caused a reduction in CaV2.2_HA proximity to and co-localization with the active zone marker RIM 1/2, as well as a lower contribution of N-type channels to single action potential-mediated Ca2+ influx. The mechanism of this down-regulation of CaV2.2_HA involves a Rab 11a-dependent trafficking process, since dominant-negative Rab11a(S25N) occludes the effect of capsaicin on presynaptic CaV2.2_HA expression, and also prevents the effect of capsaicin on action potential induced Ca2+ influx. Taken together, these data suggest that capsaicin causes a decrease in cell surface CaV2.2_HA expression in DRG terminals via a Rab11a-dependent endosomal trafficking pathway. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer
My AP Biology Thoughts Unit 2 Cell Structure and FunctionWelcome to My AP Biology Thoughts podcast, my name is Morgan Bernstein and I am your host for episode #59 Unit 2: Active Transport: Endocytosis, Exocytosis, and Protein Pumps. Segment 1: Introduction to Active TransportFirst, we have to know that within any cell, things are always moving. Proteins need to get places, waste has to be excreted, and food is consumed. Two umbrella terms of movement- Passive Transport and Active Transport Passive Transport=no energy required, almost like a habit Active transport = within a vesicle, does require energy Active transport is what we will be discussing in this episode, but be sure to check out episode 58 to learn about passive transport as well! Why does active transport require energy? Goes against the concentration gradient Things are moving from low concentration to high concentration (disrupts equilibrium and requires extra energy) Can happen across a cell membrane or within the cell itself Segment 2: Examples of Active Transport: Endo/Exocytosis and PumpsThe first type of active transport is one that does cross a cell-membrane barrier, and it is known as the sodium-potassium pump. Two potassium ions into the cell and takes three sodium ions out Works because of the protein pump in the plasma membrane. Three sodium ions bind to the carrier protein pump inside the cell, and are transported out using the energy available from ATP. Protein then changes shape to allow for the potassium ions to bind to it as well, and pumps those inside of the cell membrane where they are transported for use in the cell before the process repeats. Higher concentration of potassium ions inside the cell than outside, and a higher concentration of sodium ions outside the cell, so this sodium-potassium pump is going against the concentration gradient and is therefore a form of ACTIVE transport Requires energy. Another form of active transport comes in endocytosis and exocytosis First, cytosis means cell, which is present in all three terms Endo = enter, + cytosis = cell, so endocytosis = into the cell Exo = exit, + cytosis = cell, so exocytosis = exiting the cell. Endocytosis Things brought into the cell across the membrane, but not through a pump Requires energy Happens inside a vesicle (small cellular bubble that holds and transports other molecules and ions) Molecules or ions outside of the cell are enclosed by a part of the plasma membrane, forming the vesicle, and vesicle brings the contents through the membrane into the cell for transport Exocytosis export proteins or excrete waste products Requires energy Necessary protein or waste products inside of a transport vesicle, vesicle connects with plasma membrane and contents released into outside environment. Segment 3: Connection to the CourseActive transport has many connections to our Unit 2 about Cells and to biology in general. Goes against the rules used for any other cellular movement ex. osmosis or diffusion. Usually moving from high concentrated areas to low concentrated areas, active transport is OPPOSITE and requires energy. These processes are all due to the selective permeability of the plasma membrane of cells. Membrane structure of phospholipids and proteins (w/0 = everything or nothing would be able to enter and exit a cell) No active transport without transport vesicles and protein pumps Potassium is charged- could not enter phospholipid bilayer Important to remember the characteristics and functions of the cell membrane and organelles when studying types of cellular movement such as active transport. We can also connect active transport to the most basic of everyday activities; eating and drinking phagocytosis and pinocytosis- cellular eating and cellular drinking Without this, cells would be...
Welcome all to IS PHARMACOLOGY DIFFICULT Podcast! I am Dr Radhika Vijay.In today's episode, a little brushing before I take a deep dive in true and exact process of Pharmacokinetics, let the oven preheat before true baking starts!!The heads covered are Vesicular transport and Filtration. As I solve the puzzle of tangled and knotty wool yarn of the day's talk, the beginnings of conversation are marked by definitions and explanations of Pinocytosis and Phagocytosis, two types of Endocytosis. Its own description is as simple as simplicity.After covering details along with examples for this heads mentioned, i will shift the tides of my talk towards Exocytosis, another good simple talk unfolds in words and this is followed by something too simple equalling to 2+2 addition in mathematics, which never turns greater as 5 , or less as 3, but exactly as equal to 4. Decorated with classical antique examples, I will pull down the curtains for today's talk while slowly curbing the pace and volume of my verbal proceedings, a quick tip to revise and learn better!Just grab it hard, and make a difference in your performance, nothing left untold.......... For all the updates and latest episodes of my podcast, please visit www.ispharmacologydifficult.com where you can also sign up for a free monthly newsletter of mine. It actually contains lot of updates about the medical sciences, drug information and my podcast updates also. You can follow me on different social media handles like twitter, insta, facebook and linkedin. They all are with same name "IS PHARMACOLOGY DIFFICULT". If you are listening for the first time, do follow me here, whatever platform you are consuming this episode, stay tuned, do rate and review on ITunes, Apple podcasts, stay safe, stay happy, stay enlightened, Thank you!!
Welcome all to IS PHARMACOLOGY DIFFICULT Podcast! I am Dr Radhika Vijay. In today's episode, a little brushing before I take a deep dive in true and exact process of Pharmacokinetics, let the oven preheat before true baking starts!! The heads covered are Vesicular transport and Filtration. As I solve the puzzle of tangled and knotty wool yarn of the day's talk, the beginnings of conversation are marked by definitions and explanations of Pinocytosis and Phagocytosis, two types of Endocytosis. Its own description is as simple as simplicity.After covering details along with examples for this heads mentioned, i will shift the tides of my talk towards Exocytosis, another good simple talk unfolds in words and this is followed by something too simple equalling to 2+2 addition in mathematics, which never turns greater as 5 , or less as 3, but exactly as equal to 4. Decorated with classical antique examples, I will pull down the curtains for today's talk while slowly curbing the pace and volume of my verbal proceedings, a quick tip to revise and learn better!Just grab it hard, and make a difference in your performance, nothing left untold.......... For all the updates and latest episodes of my podcast, please visit www.ispharmacologydifficult.com where you can also sign up for a free monthly newsletter of mine. It actually contains lot of updates about the medical sciences, drug information and my podcast updates also. You can follow me on different social media handles like twitter, insta, facebook and linkedin. They all are with same name "IS PHARMACOLOGY DIFFICULT". If you are listening for the first time, do follow me here, whatever platform you are consuming this episode, stay tuned, do rate and review on ITunes, Apple podcasts, stay safe, stay happy, stay enlightened, Thank you!!
Welcome all to IS PHARMACOLOGY DIFFICULT Podcast! I am Dr Radhika Vijay.In today's episode, a little brushing before I take a deep dive in true and exact process of Pharmacokinetics, let the oven preheat before true baking starts!!The heads covered are Vesicular transport and Filtration. As I solve the puzzle of tangled and knotty wool yarn of the day's talk, the beginnings of conversation are marked by definitions and explanations of Pinocytosis and Phagocytosis, two types of Endocytosis. Its own description is as simple as simplicity.After covering details along with examples for this heads mentioned, i will shift the tides of my talk towards Exocytosis, another good simple talk unfolds in words and this is followed by something too simple equalling to 2+2 addition in mathematics, which never turns greater as 5 , or less as 3, but exactly as equal to 4. Decorated with classical antique examples, I will pull down the curtains for today's talk while slowly curbing the pace and volume of my verbal proceedings, a quick tip to revise and learn better!Just grab it hard, and make a difference in your performance, nothing left untold.......... For all the updates and latest episodes of my podcast, please visit www.ispharmacologydifficult.com where you can also sign up for a free monthly newsletter of mine. It actually contains lot of updates about the medical sciences, drug information and my podcast updates also. You can follow me on different social media handles like twitter, insta, facebook and linkedin. They all are with same name "IS PHARMACOLOGY DIFFICULT". If you are listening for the first time, do follow me here, whatever platform you are consuming this episode, stay tuned, do rate and review on ITunes, Apple podcasts, stay safe, stay happy, stay enlightened, Thank you!!
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.11.11.377515v1?rss=1 Authors: Dankovich, T. M., Kaushik, R., Cassinelli Petersen, G., Giro, P. E., Abdul Hadi, H., Bao, G., Beuermann, S., Cooper, B. H., Dityatev, A., Rizzoli, S. O. Abstract: The brain extracellular matrix (ECM) assembles around neurons and synapses, and is thought to change only rarely, through proteolysis and renewed protein synthesis. We report here an alternative ECM remodeling mechanism, based on the recycling of ECM molecules. We found that a key ECM protein, Tenascin-R, is frequently endocytosed, and later resurfaces, preferentially near synapses. The TNR molecules complete this cycle within ~3 days, in an activity-dependent fashion. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.11.03.364851v1?rss=1 Authors: Lizarrondo, J., Klebl, D. P., Niebling, S., Abella, M., Schroer, M. A., Mertens, H. D. T., Veith, K., Svergun, D. I., Skruzny, M., Sobott, F., Muench, S., Garcia-Alai, M. M. Abstract: During clathrin-mediated endocytosis, a complex and dynamic network of protein-membrane interactions cooperate to achieve membrane invagination. Throughout this process, middle coat adaptors, Sla2 and Ent1, must remain attached to the plasma membrane to transmit force from the actin cytoskeleton required for successful membrane invagination. Here, we present a cryoEM structure of a 16-mer complex of membrane binding domains from Sla2 and Ent1 that anchors to the plasma membrane. Detailed mutagenesis in vitro and in vivo of the tetramer interfaces delineate the key interactions for complex formation and deficient cell growth phenotypes demonstrate the biological relevance of these interactions. Finally, time-resolved experiments in solution suggest that adaptors have evolved to achieve a fast subsecond timescale assembly in the presence of PIP2. Together, these findings provide a molecular understanding of an essential piece for the molecular puzzle of clathrin-coated sites. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.06.327742v1?rss=1 Authors: Kliche, J., Ali, M., Ivarsson, Y. Abstract: The spike protein of the SARS-CoV-2 interacts with angiotensin converting enzyme 2 (ACE2) and enters the host cell by receptor-mediated endocytosis. Concomitantly, evidence is pointing to the involvement of additional host cell receptors, such as integrins. The cytoplasmic tails of ACE2 and integrin beta3 contain a plethora of predicted binding motifs. Here, we confirm the functionality of some of these motifs through affinity measurements. The class I PDZ binding motif in the ACE2 cytoplasmic tail binds the first PDZ domain of the scaffold protein NHERF3. The clathrin-adaptor subunit AP2 Mu2 interacts with an endocytic motif in the ACE2 with low affinity and the interaction is abolished by phosphorylation of Tyr781. Furthermore, the C-terminal region of integrin beta3 contains a LC3-interacting region, and its interaction with ATG8 domains is enhanced by phosphorylation. Together, our data provides possible molecular links between host cell receptors and endocytosis and autophagy Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.10.291062v1?rss=1 Authors: Bonnycastle, K., Kind, P. C., Cousin, M. A. Abstract: Synaptic vesicle (SV) recycling is essential for the maintenance of neurotransmission, with a number of neurodevelopmental disorders linked to defects in this process. Fragile X syndrome (FXS) results from a loss of fragile X mental retardation protein (FMRP) encoded by the FMR1 gene. FMRP is an established translation repressor, however it also has translation-independent presynaptic roles, including regulation of the trafficking and function of specific ion channels. Since defects in SV recycling are exacerbated during intense neuronal activity, we investigated whether these events were disproportionately affected by the absence of FMRP. We revealed that primary neuronal cultures from a Fmr1 knockout rat model display a specific defect in activity-dependent bulk endocytosis (ADBE). ADBE is dominant during intense neuronal activity, and this defect resulted in an inability of Fmr1 knockout neurons to sustain SV recycling during trains of high frequency stimulation. Using a molecular replacement strategy, we revealed that a human FMRP interaction mutant failed to correct ADBE dysfunction in knockout neurons. Therefore, FMRP performs a key role in sustaining neurotransmitter release via selective control of the endocytosis mode, ADBE. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.11.246363v1?rss=1 Authors: Evans, L. D., Strano, A., Campbell, A., Karakoc, E., Iorio, F., Bassett, A. R., Livesey, F. J. Abstract: Pathological protein aggregation in Alzheimers disease and other dementias is proposed to spread through the nervous system by a process of intercellular transfer of pathogenic forms of tau protein. Defining the cellular mechanisms of tau entry to human neurons is essential for understanding dementia pathogenesis and the rational design of disease-modifying therapeutics. Using whole genome CRISPR knockout screens in human iPSC-derived excitatory neurons, the primary cell type affected in these diseases, we identified genes and pathways required specifically for uptake of monomeric and aggregated tau. Monomeric and aggregated tau are both taken up by human neurons by receptor-mediated endocytosis, with the low-density lipoprotein LRP1 a significant surface receptor for both forms of tau. Perturbations of the endolysosome and autophagy systems at many levels, and specifically endosome sorting and receptor recycling, greatly reduced tau uptake. Of particular therapeutic interest is that loss of function of the endocytosis and autophagy regulator LRRK2, as well as acute inhibition of its kinase activity, reduced neuronal uptake of monomeric and aggregated tau. Kinase-activating mutations in LRRK2 are a cause of Parkinsons disease accompanied by neuronal tau aggregation, suggesting that LRRK2 mediates tau spreading in vivo and that LRRK2 inhibition has the potential to inhibit interneuronal spread of tau pathology, slowing disease progression. Overall, pathways for tau entry share significant similarity with those required for virus entry by receptor-mediated endocytosis, suggesting that tau spreading is a quasi-infectious process. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.20.211854v1?rss=1 Authors: Laporte, M. H., Chi, K. I., Rolland, M., Caudal, L. C., Martinez-Hernandez, J., Martineau, M., Chatellard, C., Denarier, E., Mercier, V., Lemaitre, F., Blot, B., Moutaux, E., Cazorla, M., Buisson, A., Perrais, D., Fraboulet, S., Lante, F., Kirchhoff, F., Hemming, F. J., Sadoul, R. Abstract: In chemical synapses undergoing high frequency stimulation, vesicle components can be retrieved from the plasma membrane via a clathrin-independent process called activity dependent bulk endocytosis (ADBE). Alix (ALG-2 interacting protein X)/ PDCD6IP) is an adaptor protein binding to ESCRT and endophilin-A proteins and thereby driving deformation and fission of endosomal and cell surface membranes. In fibroblasts, Alix is required for clathrin-independent endocytosis. Here, using electron microscopy, we show that synapses from mice lacking Alix have subtle defects in presynaptic compartments, translating into flawed synaptic plasticity. Using cultured neurons, we demonstrate that Alix is required for ADBE. We further demonstrate that in order to perform ADBE, Alix must be recruited to synapses by the calcium-binding protein ALG-2 and interact with endophilin-A. Finally, we show that mutant mice lacking Alix in the forebrain undergo less seizures during kainate-induced status epilepticus. Furthermore, propagation of the epileptiform activity to the contralateral side of kainate injection is reduced. These results thus highlight Alix ko mice as an invaluable model to study the exact role of ADBE at synapses undergoing physiological or pathological stimulations. Copy rights belong to original authors. Visit the link for more info
Drs. Petersen, Mallik and Neher discuss the latest research looking at endocytosis and calcium signaling in the context of SARS-CoV-2, organelle transport and calcium imaging.
Drs. Petersen, Mallik and Neher discuss the latest research looking at endocytosis and calcium signaling in the context of SARS-CoV-2, organelle transport and calcium imaging.
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.26.172874v1?rss=1 Authors: Cho, Y. Y., Kwon, O.-H., Chung, S. Abstract: Amyloid precursor protein (APP) at the plasma membrane is internalized via endocytosis, and delivered to endosomes and lysosomes, where neurotoxic amyloid-{beta} (A{beta}) is produced via {beta}-, {gamma}-secretases. Hence, endocytosis plays a key role in the processing of APP and subsequent A{beta} generation. {beta}-, {gamma}-secretases as well as APP are localized in cholesterol-enriched lipid raft microdomains. However, it is still unclear whether lipid rafts are the site where APP undergoes endocytosis and whether cholesterol levels affect this process. In this study, we found that localization of APP in lipid rafts was increased by elevated cholesterol level. We also showed that increasing or decreasing cholesterol levels increased or decreased APP endocytosis, respectively. When we labeled cell surface APP, APP localized in lipid rafts preferentially underwent endocytosis compared to non-raft localized APP. In addition, APP endocytosis from lipid rafts was regulated by cholesterol levels. Our results indicate that cholesterol levels regulate the localization of APP in lipid rafts affecting raft-dependent APP endocytosis. Thus, regulating the microdomain localization of APP could offer a new therapeutic strategy for Alzheimer's disease. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.22.164400v1?rss=1 Authors: Yao, C.-K., Li, T.-N., Chen, Y.-J., Wang, Y.-T., Lin, H.-C. Abstract: Synaptic vesicle (SV) endocytosis is coupled to exocytosis to maintain SV pool size and thus neurotransmitter release. Intense stimulation induces activity-dependent bulk endocytosis (ADBE) to recapture large quantities of SV constituents in large endosomes from which SVs reform. How these consecutive processes are spatiotemporally coordinated remains unknown. Here, we show that the Flower Ca2+ channel-dependent phosphatidylinositol 4,5-bisphosphate (PIP2) compartmentalization governs such control. Strong stimuli trigger PIP2 microdomain formation at periactive zones. Upon exocytosis Flower translocates from SVs to periactive zones, where it increases PIP2 levels via Ca2+ influxes. Remarkably, PIP2 directly enhances Flower channel activity, thereby establishing a positive feedback loop for PIP2 microdomain compartmentalization. The PIP2 microdomains drive ADBE and SV reformation from bulk endosomes. PIP2 further sorts Flower to bulk endosomes, thereby terminating endocytosis. Hence, we propose that the interplay between Flower and PIP2 is the crucial spatiotemporal cue that couples exocytosis to ADBE and subsequent SV reformation. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.18.158709v1?rss=1 Authors: Schechter, M., Atias, M., Abd Elhadi, S., Davidi, D., Gitler, D., Sharon, R. Abstract: alpha-Synuclein (a-Syn) is a protein implicated in the pathogenesis of Parkinson s disease (PD). It is an intrinsically disordered protein that binds acidic phospholipids. Growing evidence supports a role for a-Syn in membrane trafficking, including, mechanisms of endocytosis and exocytosis, although the exact role of a-Syn in these mechanisms is currently unclear. Here we have investigated the role of a-Syn in membrane trafficking through its association with acidic phosphoinositides (PIPs), such as phosphatidylinositol 4,5-bisphosphate (PI4,5P2) and phosphatidylinositol 3,4-bisphosphate (PI3,4P2). Our results show that a-Syn colocalizes with PIP2 and the phosphorylated active form of the clathrin adaptor AP2 at clathrin-coated pits. Using endocytosis of transferrin, an indicator of clathrin mediated endocytosis (CME), we find that a-Syn involvement in endocytosis is specifically mediated through PI4,5P2 levels. We further show that the rate of synaptic vesicle (SV) endocytosis is differentially affected by a-Syn mutations. In accord with their effects on PI4,5P2 levels at the plasma membrane, the PD associated E46K and A53T mutations further enhance SV endocytosis. However, neither A30P mutation, nor Lysine to Glutamic acid substitutions at the KTKEGV repeat domain of a-Syn, that interfere with phospholipid binding, affect SV endocytosis. This study provides evidence for a critical involvement of PIPs in a-Syn-mediated membrane trafficking. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.27.119388v1?rss=1 Authors: Liu, Q., Bautista-Gomez, J., Higgins, D. A., Yu, J., Xiong, Y. Abstract: Recent genetic evidence revealed that endocytic pathway plays a major role in Parkinsons disease (PD) risk. However, the molecular mechanism of how endocytic defects contribute to dopaminergic neurodegeneration in PD is poorly understood. Here we report that LRRK2, the mutations of which are the most genetic causes of PD, binds to and phosphorylates AP2M1, the core component of endocytosis that has been recently implicated in PD risk. Our study revealed that abnormal AP2M1 phosphorylation cycle, regulated either by knockout or overexpression of LRRK2, cause endocytic defects. Our study also uncovered a novel tissue-specific regulation of AP2M1 phosphorylation by LRRK2. Further, we found that LRRK2 phosphorylation on AP2M1 mediates LRRK2-induced neuronal toxicity both in vitro in neuronal cultures and in vivo in Drosophila dopamine neurons. Importantly, AP2M1 phosphorylation levels are elevated in patient fibroblasts of both LRRK2-associated PD and sporadic PD, suggesting the clinical relevance of our finding in PD. Together, our study provides a direct mechanistic link between LRRK2, AP2 and endocytosis in PD pathogenesis. Copy rights belong to original authors. Visit the link for more info
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.04.29.069344v1?rss=1 Authors: Vargas, K. J., Colosi, P. L., Girardi, E., Chandra, S. S. Abstract: -Synuclein plays a central role in Parkinson disease (PD); hence, elucidating its normal physiological function(s) is important. -Synuclein and family members {beta}-, and {gamma}-synuclein, are presynaptically enriched proteins. Synucleins sense and generate membrane curvature, properties consistent with their described roles in synaptic vesicle (SV) cycling. We have previously shown SV endocytosis (SVE) deficits in {beta}{gamma}-synuclein knockout (KO) neurons. Here, we investigate which steps of SVE are regulated by -synuclein. Immuno-electron microscopy (EM) of synaptosomes reveals that -synuclein relocalizes from SVs to the synaptic membrane upon stimulation, allowing -synuclein to function there during or after stimulation. Using membrane recruitment assays, we show that -synuclein is co-localized with clathrin patches. We also observe that recruitment of clathrin and its adaptor, AP180, to synaptic membranes is altered in the absence of synucleins. Visualizing clathrin assembly on membranes in an in vitro reconstitution system reveal that synucleins increase clathrin patch size and curvature, facilitating clathrin coated pit maturation during the early steps of SVE. Copy rights belong to original authors. Visit the link for more info
The TWiP professors solve the case of the Ugandan Child with Splenomegaly, and reveal that mutations in the P. falciparum genome that confer artemisinin resistance interfere with endocytic uptake of hemoglobin. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Subscribe (free): iTunes, Google Podcasts, RSS, email Links for this episode PWB social media: Facebook, Instagram, Twitter Endocytosis pathway mediates artemisinin resistance in malaria parasites (Science) Letters read on TWiP 180 Become a patron of TWiP. Case Study for TWiP 180 Uganda with a twist. Meets two people with watery diarrhea, 12 episodes/day, loss of appetite. No fever, no blood in stool. Living for months at staff guest house. One week prior to onset went on weekend trip to area with waterfalls. Were served outdoor meal: meat, salad, fruit. Recommends empiric treatment trimethoprim/sulfamethoxzole for 7 days. Prompt resolution of diarrhea. A few days later, upon drinking coffee with milk gets severe cramps. 20s, long term female volunteers. Send your case diagnosis, questions and comments to twip@microbe.tv Music by Ronald Jenkees
Active Transport, Endocytosis, Phagocytosis, Pinocytosis, and Exocytosis are discussed during this segment.
Drubin explains how he and his lab transferred their knowledge of endocytosis in yeast to determine how actin dynamics are harnessed to drive endocytic traffic in mammalian cells. In mammalian cells, his team observed the importance of actin-dynamin interactions in clathrin-dependent endocytosis. Interestingly, they found variability in endocytic site morphology and dynamics. Studies using stem cells suggested that this diversity in actin-mediated endocytosis is important for determining cell identity and development.
Actin forms many cellular structures and regulates a variety of critical biological processes. Dr. David Drubin's lab focuses on studying actin in the context of membrane trafficking. In his first iBiology seminar, Drubin recounts seminal research done using the intracellular pathogen Listeria that uncovered how the bacteria harnesses phagocytosis and actin polymerization to facilitate motility. These initial studies led to the discovery of key regulators of actin filament formation including Arp2/3 and N-WASP. Advances in yeast genetics, biochemistry and imaging then allowed Drubin and others to expand their studies to actin dynamics and endocytosis in yeast.
Drubin describes how his lab began studying actin dynamics and endocytosis in yeast using two-color, real-time fluorescence and kymographs. These tools enabled his team to confirm that actin regulated clathrin-mediated endocytosis. They discovered that BAR and F-BAR proteins stabilized the process by acting as a scaffold for actin and facilitating invagination and fission of the cell membrane to develop vesicles.
Andrews further explains how Ca2+-dependent exocytosis of lysosomes aids membrane repair. Her laboratory showed that after lysosomal exocytosis, an injury to the plasma membrane would also trigger a Ca2+-dependent endocytosis that is required for the repair mechanism. Andrews laboratory showed that lysosomes release the enzyme acid sphingomyelinase (ASM) which induce the endocytosis required for plasma membrane repair.
The TWiVers present mitoviruses, which infect mitochondria, and how quasi-enveloped hepatitis A virus gets naked again. Hosts: Vincent Racaniello, Dickson Despommier, Alan Dove, and Kathy Spindler Subscribe (free): iTunes, Google Podcasts, RSS, email Become a patron of TWiV! Links for this episode Evidence for plant mitoviruses (Virology) Uncoating of quasi-enveloped HAV (eLife) Image credit Letters read on TWiV 541 Timestamps by Jolene. Thanks! Weekly Science Picks Alan- Where and when to see cherry blossoms Dickson- Nebraska floods Kathy- Peeps fungal infection experiment Vincent - Emergency declared in NY over measles, unvaccinated barred from public spaces Listener Pick Sam- STLR conversations Josh- Tree of Life Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
The TWiVers present mitoviruses, which infect mitochondria, and how quasi-enveloped hepatitis A virus gets naked again. Hosts: Vincent Racaniello, Dickson Despommier, Alan Dove, and Kathy Spindler Subscribe (free): iTunes, Google Podcasts, RSS, email Become a patron of TWiV! Links for this episode Evidence for plant mitoviruses (Virology) Uncoating of quasi-enveloped HAV (eLife) Image credit Letters read on TWiV 541 Timestamps by Jolene. Thanks! Weekly Science Picks Alan- Where and when to see cherry blossoms Dickson- Nebraska floods Kathy- Peeps fungal infection experiment Vincent - Emergency declared in NY over measles, unvaccinated barred from public spaces Listener Pick Sam- STLR conversations Josh- Tree of Life Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
The TWiV team discuss the use of quantum dots to study uncoating of influenza virus in real time, and induction of endothelial dysfunction by flavivirus NS1 proteins in a tissue-specific manner. Hosts: Vincent Racaniello, Dickson Despommier, Rich Condit, and Brianne Barker Subscribe (free): iTunes, Google Podcasts, RSS, email Become a patron of TWiV! Links for this episode European Congress of Virology 2019 ASM Clinical Virology Symposium Intel ISEF judges needed Quantum dots to visualize influenza entry (PNAS) Quantum dots (Wikipedia) Flavivirus NS1 triggers endothelial dysfunction (Cell Rep) Image credit Letters read on TWiV 535 Timestamps by Jolene. Thanks! Weekly Science Picks Brianne - Hotel Influenza Alan- Your town’s climate in 60 years Dickson- BMC Research in Progress Photo Competition Rich- NASA's Opportunity Rover Mission on Mars Ends (landing animation) Vincent - Watch a single cell become a complex organism in six minutes Listener Pick Anne- Pathogenesis II Kickstarter Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
The TWiV team discuss the use of quantum dots to study uncoating of influenza virus in real time, and induction of endothelial dysfunction by flavivirus NS1 proteins in a tissue-specific manner. Hosts: Vincent Racaniello, Dickson Despommier, Rich Condit, and Brianne Barker Subscribe (free): iTunes, Google Podcasts, RSS, email Become a patron of TWiV! Links for this episode European Congress of Virology 2019 ASM Clinical Virology Symposium Intel ISEF judges needed Quantum dots to visualize influenza entry (PNAS) Quantum dots (Wikipedia) Flavivirus NS1 triggers endothelial dysfunction (Cell Rep) Image credit Letters read on TWiV 535 Timestamps by Jolene. Thanks! Weekly Science Picks Brianne - Hotel Influenza Alan- Your town’s climate in 60 years Dickson- BMC Research in Progress Photo Competition Rich- NASA's Opportunity Rover Mission on Mars Ends (landing animation) Vincent - Watch a single cell become a complex organism in six minutes Listener Pick Anne- Pathogenesis II Kickstarter Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
The TWiV crew reveal a unique portal on the calcivirus capsid formed upon receptor engagement, and the regulation of interferon responses in virus-infected cells by methylation of mRNA. Hosts: Vincent Racaniello, Dickson Despommier, Kathy Spindler, and Brianne Barker Subscribe (free): iTunes, Google Podcasts, RSS, email Become a patron of TWiV! Links for this episode European Congress of Virology 2019 ASM Clinical Virology Symposium Intel ISEF judges needed Calicivirus portal visualized (Nature) Calicivirus portal - long version (biorXiv) m6A modification and innate response (Nat Immunol) Brianne Barker's immunology course m6A modification and innate response (Genes Dev) Letters read on TWiV 534 Timestamps by Jolene. Thanks! Weekly Science Picks Brianne - The Red Queen's Race Card Game Alan- Pentax Papilio II Dickson- Felice Frankel on improving visual side of science Kathy- History of the alphabet chart (free download) usefulcharts.com (see blog, such as Latin Greek Cyrillic Venn Diagram) Vincent - Virology Lectures 2019 Listener Pick Peter- Microbehunter (YouTube, blog, forum) Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
The TWiV crew reveal a unique portal on the calcivirus capsid formed upon receptor engagement, and the regulation of interferon responses in virus-infected cells by methylation of mRNA. Hosts: Vincent Racaniello, Dickson Despommier, Kathy Spindler, and Brianne Barker Subscribe (free): iTunes, Google Podcasts, RSS, email Become a patron of TWiV! Links for this episode European Congress of Virology 2019 ASM Clinical Virology Symposium Intel ISEF judges needed Calicivirus portal visualized (Nature) Calicivirus portal - long version (biorXiv) m6A modification and innate response (Nat Immunol) Brianne Barker's immunology course m6A modification and innate response (Genes Dev) Letters read on TWiV 534 Timestamps by Jolene. Thanks! Weekly Science Picks Brianne - The Red Queen's Race Card Game Alan- Pentax Papilio II Dickson- Felice Frankel on improving visual side of science Kathy- History of the alphabet chart (free download) usefulcharts.com (see blog, such as Latin Greek Cyrillic Venn Diagram) Vincent - Virology Lectures 2019 Listener Pick Peter- Microbehunter (YouTube, blog, forum) Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
The TWiVerati follow up on the Ebola virus outbreak, virulence of Ebola-Makona, and reveal how a parasitoid is revealed to hyperparasitoids, and binding of influenza virus to a calcium ion channel to mediate influenza virus entry. Hosts: Vincent Racaniello, Alan Dove, and Kathy Spindler Become a patron of TWiV! Links for this episode ASM Microbe 2018 Support Viruses & Cells Gordon Conference Faculty positions at Icahn School of Medicine International dsRNA Virus Symposium Tracing Ebola virus contacts(CIDRAP) WHO FAQ Ebola virus vaccine(WHO) Nipah virusoutbreak (CIDRAP) Revealingparasitoid to hyperparasitoid (PNAS) Hyperparasitoidvideo (YouTube) Calcium channeland influenza virus entry (Cell Host Microbe) Letters readon TWiV 495 Weekly Science Picks Alan - National Cryptologic Museum Rich - Science is mostly about staring Dickson - New Zealand gloworms Kathy - Openingof Smithsonian Outbreak; conference advice General ASV Vincent - ICTV online Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
Cytotoxic T cells use Flower power In order to efficiently kill multiple target cells, cytotoxic T lymphocytes must endocytose and recycle cytotoxic granule membrane components from the immunological synapse. Chang et al. reveal that a protein called Flower facilitates granule endocytosis in a calcium-dependent manner. This biosights episode presents the paper by Chang et al. from the February 5th, 2018, issue of the Journal of Cell Biology and includes an interview with one of the paper's senior authors, Jens Rettig (Saarland University, Saarbrücken, Germany). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research. Subscribe to biosights via iTunes or RSS View biosights archive The Rockefeller University Press biosights@rockefeller.edu
The TWiV ninjas reveal that bacteriophage particles rapidly move across monolayers of eukaryotic cells from different tissues. Hosts: Vincent Racaniello, Dickson Despommier, Alan Dove, Rich Condit, and Kathy Spindler Become a patron of TWiV! Links for this episode Transcytosis of bacteriophage across cell layers (mBio) Image credit Letters read on TWiV 470 This episode is brought to you by Blue Apron. Blue Apron is the #1 fresh ingredient and recipe delivery service in the country. Get $30 off your first delivery and FREE SHIPPING by going to blueapron.com/twiv. Weekly Science Picks Kathy - Photo of 3200 year-old tree in one image Dickson - Microsculpture Rich - A Short History Of Humans And Germs Alan - Planets app Vincent - Laptops Are Great. But Not During a Lecture or a Meeting Listener Picks Basel - Joint Pathology Center John - OpenStax Intro music is by Ronald Jenkees. Send your virology questions and comments to twiv@microbe.tv
Hosts: Vincent Racaniello, Dickson Despommier, Alan Dove, Rich Condit, and Kathy Spindler Guest: Jeremy Luban Jeremy joins the TWiVeroids to tell the amazing story of how the function of the HIV-1 protein called Nef was discovered and found to promote infection by excluding the host protein SERINC from virus particles. Become a patron of TWiV! Links for this episode No recovery in PACE trial (virology blog) The real PACE data (virology blog) Contagious Thinking Florida DOH daily Zika update Congress does not fail on Zika (NPR) Nef history (Luban lab) Nef excludes SERINC from virions (Nature) SERINC counters Nef (Nature) ASM Grant Writing Online Course Letters read on TWiV 409 This episode is brought to you by CuriosityStream, a subscription streaming service that offers over 1,400 documentaries and nonfiction series from the world's best filmmakers. Get unlimited access starting at just $2.99 a month, and for our audience, the first two months are completely free if you sign up at curiositystream.com/microbe and use the promo code MICROBE. 0:25, 28:50 This episode is also brought to you by Drobo, a family of safe, expandable, yet simple to use storage arrays. Drobos are designed to protect your important data forever. Visit www.drobo.com to learn more. Listeners can save $100 on a Drobo system at drobostore.com by using the discount code Microbe100. Weekly Science Picks Alan - Migration in MotionDickson - Beautiful Chemistry Rich - XKCD Timeline of Earth Temperature Kathy - Vaccine Heroes from Vaccine Education CenterJeremy - CIDRAP posters and Demon in the Freezer Vincent - People Peas and Pathogens Listener Picks Matlock - Science isn't broken Send your virology questions and comments to twiv@microbe.tv
Septins step in to promote macropinosome fusion After they are formed by the closure of membrane ruffles, macropinosomes mature by fusing with each other and with endosomes, before eventually delivering their fluid phase cargo to lysosomes. Dolat and Spiliotis reveal that septin filaments promote macropinosome maturation and lysosomal delivery by facilitating macropinosome/endosome fusion. This biosights episode presents the paper by Dolat and Spiliotis from the August 29th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Elias Spiliotis (Drexel University, Philadelphia, PA). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research. Subscribe to biosights via iTunes or RSS View biosights archive The Rockefeller University Press biosights@rockefeller.edu
Surf's uptake! Exosomes ride filopodia into cells Exosomes are small, extracellular vesicles that transfer lipid, protein, and RNA cargoes between cells, but relatively little is known about how they are taken up and processed by their target cells. Heusermann et al. reveal that exosomes "surf" along recipient cell filopodia before being efficiently endocytosed and targeted to the endoplasmic reticulum. This biosights episode presents the paper by Heusermann et al. from the April 25, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Nicole Meisner-Kober (Novartis Institutes for Biomedical Research, Basel, Switzerland). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research. Subscribe to biosights via iTunes or RSS View biosights archive The Rockefeller University Press biosights@rockefeller.edu
Roy Silverstein explains how the Na+/K+-ATPase helps turn macrophages into foam cells at atherosclerotic plaques.
Endocytosis brings closure to epithelial wounds Epithelial cells bordering a wound respond by forming two types of actin-based structure: dynamic membrane protrusions that help the cells crawl into the wound and/or seal it and an actomyosin cable that encircles the wound and closes it like a purse string. Matsubayashi et al. reveal that the endocytic remodeling of intercellular adherens junctions promotes Drosophila epidermal wound healing by coordinating the activity of multiple actin regulators at the wound edge. This biosights episode presents the paper by Matsubayashi et al. from the August 3rd, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Tom Millard (University of Manchester, Manchester, UK). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research. Subscribe to biosights via iTunes or RSS View biosights archive The Rockefeller University Press biosights@rockefeller.edu
Vincent, Dickson, and Daniel explain how trypanolytic factor forms membrane channels to lyse trypanosomes, and present a new case study. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Links for this episode: Human trypanolytic factor forms channels (PNAS) Human paragonimiasis (MMWR) Don't eat raw crawfish Daniel and Dickson in studio (jpg) Image credit Letters read on TWiP 85 Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv Subscribe Subscribe to TWiP (free) in iTunes, by the RSS feed or by email
Lowengrub, J (University of California, Irvine) Friday 27 June 2014, 10:00-10:45
Activation of the calcium-sensing receptor promotes its trafficking to the cell surface and enhances signaling.
Alexander Sorkin, PhD, University of Pittsburgh, Pittsburgh, Pennsylvania
Fakultät für Biologie - Digitale Hochschulschriften der LMU - Teil 04/06
The yeast plasma membrane contains at least three microdomains – membrane compartment containing Pma1 (MCP), membrane compartment containing TORC2 (MCT) and membrane compartment containing Can1 (MCC). Eisosomes underlie the MCC domain defined by the marker protein arginine permease (Can1). Eisosomes are large protein assemblies composed of Pil1 and Lsp1 proteins, of which Pil1 is essential for plasma membrane organization. We found that the uncharacterized AAA-ATPase protein Yta6 dynamically colocalizes with eisosomes. Yta6 physically interacts with eisosome components, specifically with Pil1. In PIL1 deletion cells, Yta6 is unable to localize normally to the plasma membrane. Yta6 foci colocalize with the intermediates of FM4-64 on the plasma membrane. The number of these intermediates is increased upon overexpression of Yta6. Overexpressed Yta6 is also able to rescue the defects of endocytosis in cells devoid of amphiphysins. Together rescue experiments and colocalization of a protein cargo Hxt3 with eisosomes suggest that Yta6 likely plays a role in endocytosis at eisosomes. To identify genes whose products function together with eisosome components, we independently carried out a genetic interaction study (epistatic mini array profile) which revealed the protein Emp70. EMP70 showed the strongest correlation in genetic profile with PIL1. Emp70 localizes to a subset of eisosomes in addition to its localization in endosomes and vacuoles. We found eisosomes are required for normal numbers of Emp70 plasma membrane foci. Deletion of Emp70 misdirected endosomal protein Kex2 to vacuole, implicating its essential role in maintaining the architecture of the endosomal compartment. In summary, Yta6 likely plays a role in initiation of endocytosis at eisosomes and Emp70 during intracellular trafficking from plasma membrane to vacuole.
Opioid receptors stimulated with morphine signal less efficiently than those stimulated with an endogenous opioid peptide.
Vincent and Dick continue virology 101 with a discussion of virus entry into cells, then answer reader email on colony collapse disorder and viruses that confer a benefit to their host. Links for this episode: Illustrations of virus entry into cells Nice reference for biological items (thanks Jim!) Colony collapse disorder: PBS program, descriptive study, metagenomic study, genetic analysis (thanks Swiss compass!) Potato virus Y and Alzheimer's disease (thanks Jennifer!) A virus in a fungus in a plant (thanks Jennifer!) Weekly Science Picks Vincent PLoS PearlsDick West Nile virus website at CDC
Fakultät für Biologie - Digitale Hochschulschriften der LMU - Teil 03/06
Vesicle traffic in eukaryotic cells is a tightly organized process involving a multitude of regulatory proteins. Key regulators of this traffic are small GTPases called Rabs. With about 60 members in the human genome, they constitute the largest subgroup in the superfamily of Ras like monomeric GTPases. They recruit effector proteins to specific membranes and thus define the identity of organelles. Rabs switch between an active, GTP bound state and an inactive GDP bound state. Key regulators of this conversion are RabGAPs, which accelerate the hydrolysis of bound GTP. All RabGAPs are characterized by the presence of a TBC domain. In the human genome 40 RabGAPs were identified, most of which had not been studied so far. To assign them to their specific Rab proteins, a novel reverse yeast two-hybrid screening method was developed. This identified a GAP for Rab5 termed RabGAP-5. RabGAP-5 stimulated the GTPase activity of Rab5. Its expression inactivated Rab5 and redistributed the Rab5 effector EEA1 from early endosomes to the cytoplasm. RabGAP-5 also blocked the Rab5 dependent uptake of EGF and transferrin from the plasma membrane. When RabGAP-5 was depleted, the size of endosomes was increased, indicating elevated Rab5-GTP levels. Endocytosed EGF was unable to exit the endosome, indicating that trafficking through endosomes was also blocked. To identify GAPs and Rabs implicated in the regulation of early secretory events simultaneously, a second novel screening method was established. It involved the analysis of phenotypes caused by the inactivation of endogenous target Rabs via the overexpression of RabGAPs. Changes in Golgi morphology, ERGIC organisation and the proceeding of secretion were only observed with one candidate RabGAP, the highly conserved protein TBC1D20. TBC1D20 showed activity towards Rab1 and Rab2 in vitro, and acted primarily on Rab1 in vivo. In contrast to all other RabGAPs it has a transmembrane domain, which localises it to the ER. TBC1D20 interacts with RTN-1 on ER membranes. This interaction modulates the activity of TBC1D20. These data indicate a novel function for Rab1 in regulating ER exit, and thus extend the classical view of RabGAPs as regulators of active Rab lifetime.
This poscast discusses cell echange with the environment.
Fakultät für Biologie - Digitale Hochschulschriften der LMU - Teil 01/06
Eph receptors and their membrane associated ephrin ligands mediate cell-cell repulsion to guide migrating cells and axons. A peculiarity of this signaling system is that both receptors and ligands can transduce signals into the cell resulting in a bidirectional signaling mode. An important step of ephrinB ligand ‘reverse signaling’ is the regulated tyrosine phosphorylation of the cytoplasmic domain, initiating docking sites for downstream signaling adaptors. Moreover, ephrinB ligands can signal by interactions with various PDZ-domain containing proteins. Using a broad range of in vitro assays the presented work demonstrates that upon binding to their cognate receptor, ephrinB ligands rapidly activate Src family kinases (SFKs) which subsequently phosphorylate ephrinB. Tyrosine phosphorylation appears to be a transient event that is downregulated by the tyrosine phosphatase PTP-BL, which interacts with ephrinB via one of its PDZ-domains. Studies on PTP-BL and another multiple PDZ domain containing protein GRIP (Glutamate Receptor Interacting Protein) revealed that PDZ interactions with ephrinB are also regulated by EphB receptor binding but, unlike tyrosine phosphorylation, these interactions are long lasting. These findings led to postulate a ‘switch model’ for ephrinB reverse signaling: Tyrosine dependent signaling appears to be a rapid and transient event which is later replaced by stable PDZ-dependent signaling. EphB ‘forward’ signaling as well as ephrinB ‘reverse’ signaling are important for axonal pathfinding and cell migration during development. Prior to their repellent effect on migrating cells and growth cones, Eph receptors form a high affinity complex with their ligands at sites of cell-cell contact. Therefore, mechanisms have to be in place that allow cells to detach from each other permitting retraction and withdrawal. To overcome this adhesive barrier, the ectodomain of ephrinA ligands is cleaved by metalloproteinases and shed upon receptor binding. Intrigued by the previous findings that activated ephrins cluster in cells, we hypothesized that these Eph/ephrin clusters undergo endocytosis. We developed immunofluorescence internalization and co-culture assays to study clustering and endocytosis at cell-cell contact sites. We established an experimental setup to perform fast time lapse imaging studies of cells expressing different fluorescently tagged proteins. Cell contact-induced ephrinB-EphB complexes are rapidly endocytosed during the retraction of cells and neuronal growth cones. Endocytosis occurs in a bidirectional manner, leading to internalized complexes of full length receptor and ligand, a yet rarely observed phenomenon. Signaling inactive mutants of EphB receptors and ephrinB ligands lead to a strong adhesion between cells. Endocytosis is sufficient to convert this adhesion into the detachment of cells. Bidirectional endocytosis is necessary to efficiently promote axon detachment during growth cone collapse mediated by ephrinB ligands. On the cell biological level, bidirectional endocytosis of two full length transmembrane (TM) proteins is a new phenomenon. Moreover, these studies reveal a novel mechanism of signal termination, de-adhesion and promotion of cell repulsion after intercellular (trans) interaction between two TM proteins.
Transferrin, an iron-transporting serum glycoprotein, is efficiently taken up into cells by the process of receptor-mediated endocytosis. Transferrin receptors are found on the surface of most proliferating cells, in elevated numbers on erythroblasts and on many kinds of tumors. The efficient cellular mechanism for uptake of transferrin has been subverted for the delivery of low-molecular-weight drugs, protein toxins, and liposomes by linkage of these agents to transferrin or to anti-transferrin receptor antibodies. Linkage may be via chemical conjugation procedures or by the generation of chimeric fusion proteins. Transferrin conjugated to DNA-binding compounds (e.g. polycations or intercalating agents) has been successfully used for the import of DNA molecules into cells. High-level gene expression is obtained only if endosome-disruptive agents such as influenza hemagglutinin peptides or adenovirus particles are included which release the DNA complex from intracellular vesicles into the cytoplasm.
Fri, 1 Jan 1993 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4048/ http://epub.ub.uni-muenchen.de/4048/1/027.pdf Michael, S. I.; Huang, C. H.; Romer, M.; Wagner, Ernst; Hu, P.-C.; Curiel, David T. Michael, S. I.; Huang, C. H.; Romer, M.; Wagner, Ernst; Hu, P.-C. und Curiel, David T. (1993): Binding-incompetent adenovirus facilitates molecular conjugate-mediated gene transfer by the receptor-mediated endocytosis pathway. In: Journal of Biological Chemistry, Vol. 268: pp. 6866-6869.
Wed, 1 Jan 1992 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4041/ http://epub.ub.uni-muenchen.de/4041/1/4041.pdf Curiel, David T.; Agarwal, Santosh; Romer, N.; Wagner, Ernst; Cotten, Matt; Birnstiel, Max L.; Boucher, R. C. Curiel, David T.; Agarwal, Santosh; Romer, N.; Wagner, Ernst; Cotten, Matt; Birnstiel, Max L. und Boucher, R. C. (1992): Gene transfer to respiratory epithelial cells via the receptor-mediated endocytosis pathway. In: American Journal of Respiratory Cell and Molecular Biology, Vol. 6: pp. 247-252.
Wed, 1 Jan 1992 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4034/ http://epub.ub.uni-muenchen.de/4034/1/024.pdf Plank, Christian; Zatloukal, Kurt; Cotten, Matt; Mechtler, Karl; Wagner, Ernst Plank, Christian; Zatloukal, Kurt; Cotten, Matt; Mechtler, Karl und Wagner, Ernst (1992): Gene transfer into hepatocytes using asialoglycoprotein receptor mediated endocytosis of DNA complexed with an artificial tetra-antennary galactose ligand. In: Bioconjugate Chemistry, Vol.
Mon, 1 Jan 1990 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4029/ http://epub.ub.uni-muenchen.de/4029/1/008.pdf Zenke, Martin; Steinlein, Peter; Wagner, Ernst; Cotten, Matt; Beug, Hartmut; Birnstiel, Max L. Zenke, Martin; Steinlein, Peter; Wagner, Ernst; Cotten, Matt; Beug, Hartmut und Birnstiel, Max L. (1990): Receptor-mediated endocytosis of transferrin-polycation conjugates. An efficient way to introduce DNA into hematopoietic cells. In: Proceedings of the National Academy of Science of the U S A, Vol. 87, Nr. 10: pp. 3655-3659.
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