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Wang Y, Yang Q, Meng X, Wijaya CS, Ren X, Xu S. Recruitment of tetraspanin TSP-15 to epidermal wounds promotes plasma membrane repair in C. elegans. Dev Cell 2022; 57:1630-1642.e4. [PMID: 35777354 DOI: 10.1016/j.devcel.2022.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 04/26/2022] [Accepted: 06/07/2022] [Indexed: 01/14/2023]
Abstract
Maintaining the integrity of the plasma membrane after cellular damage is essential for cell survival. However, it is unclear how cells repair large membrane injuries in vivo. Here, we report that the tetraspanin protein, TSP-15, is recruited to large membrane wounds and forms a ring-like structure in C. elegans epidermis and promotes membrane repair after an injury. TSP-15 recruits from the adjacent region underneath the plasma membrane to the wound site in a RAB-5-dependent manner upon membrane damage. Genetic and live-imaging analysis suggested that the endosomal sorting complex required for transport III (ESCRT III) is necessary for recruiting TSP-15 from the early endosome to the damaged membrane. Moreover, TSP-15 interacts with and is required for the accumulation of t-SNARE protein Syntaxin-2, which facilitates membrane repair. These findings provide valuable insights into the role of the conserved tetraspanin TSP-15 in the cellular repair of large wounds resulting from environmental insults.
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Jayaraman A, Htike TT, James R, Picon C, Reynolds R. TNF-mediated neuroinflammation is linked to neuronal necroptosis in Alzheimer's disease hippocampus. Acta Neuropathol Commun 2021; 9:159. [PMID: 34625123 PMCID: PMC8501605 DOI: 10.1186/s40478-021-01264-w] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/17/2021] [Indexed: 12/12/2022] Open
Abstract
The pathogenetic mechanisms underlying neuronal death and dysfunction in Alzheimer’s disease (AD) remain unclear. However, chronic neuroinflammation has been implicated in stimulating or exacerbating neuronal damage. The tumor necrosis factor (TNF) superfamily of cytokines are involved in many systemic chronic inflammatory and degenerative conditions and are amongst the key mediators of neuroinflammation. TNF binds to the TNFR1 and TNFR2 receptors to activate diverse cellular responses that can be either neuroprotective or neurodegenerative. In particular, TNF can induce programmed necrosis or necroptosis in an inflammatory environment. Although activation of necroptosis has recently been demonstrated in the AD brain, its significance in AD neuron loss and the role of TNF signaling is unclear. We demonstrate an increase in expression of multiple proteins in the TNF/TNF receptor-1-mediated necroptosis pathway in the AD post-mortem brain, as indicated by the phosphorylation of RIPK3 and MLKL, predominantly observed in the CA1 pyramidal neurons. The density of phosphoRIPK3 + and phosphoMLKL + neurons correlated inversely with total neuron density and showed significant sexual dimorphism within the AD cohort. In addition, apoptotic signaling was not significantly activated in the AD brain compared to the control brain. Exposure of human iPSC-derived glutamatergic neurons to TNF increased necroptotic cell death when apoptosis was inhibited, which was significantly reversed by small molecule inhibitors of RIPK1, RIPK3, and MLKL. In the post-mortem AD brain and in human iPSC neurons, in response to TNF, we show evidence of altered expression of proteins of the ESCRT III complex, which has been recently suggested as an antagonist of necroptosis and a possible mechanism by which cells can survive after necroptosis has been triggered. Taken together, our results suggest that neuronal loss in AD is due to TNF-mediated necroptosis rather than apoptosis, which is amenable to therapeutic intervention at several points in the signaling pathway.
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Nepal B, Sepehri A, Lazaridis T. Mechanisms of negative membrane curvature sensing and generation by ESCRT III subunit Snf7. Protein Sci 2020; 29:1473-1485. [PMID: 32142182 DOI: 10.1002/pro.3851] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 12/13/2022]
Abstract
Certain proteins have the propensity to bind to negatively curved membranes and generate negative membrane curvature. The mechanism of action of these proteins is much less studied and understood than those that sense and generate positive curvature. In this work, we use implicit membrane modeling to explore the mechanism of an important negative curvature sensing and generating protein: the main ESCRT III subunit Snf7. We find that Snf7 monomers alone can sense negative curvature and that curvature sensitivity increases for dimers and trimers. We have observed spontaneous bending of Snf7 oligomers into circular structures with preferred radius of ~20 nm. The preferred curvature of Snf7 filaments is further confirmed by the simulations of preformed spirals on a cylindrical membrane surface. Snf7 filaments cannot bind with the same interface to flat and curved membranes. We find that even when a filament has the preferred radius, it is always less stable on the flat membrane surface than on the interior cylindrical membrane surface. This provides an additional energy for membrane bending which has not been considered in the spiral spring model. Furthermore, the rings on the cylindrical spirals are bridged together by helix 4 and hence are extra stabilized compared to the spirals on the flat membrane surface.
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Affiliation(s)
- Binod Nepal
- Department of Chemistry, City College of New York, New York, New York, USA
| | - Aliasghar Sepehri
- Department of Chemistry, City College of New York, New York, New York, USA
| | - Themis Lazaridis
- Department of Chemistry, City College of New York, New York, New York, USA.,Graduate Programs in Chemistry, Biochemistry, and Physics, The Graduate Center, City University of New York, New York, New York, USA
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Kumar H, Pushpa K, Kumari A, Verma K, Pergu R, Mylavarapu SVS. The exocyst complex and Rab5 are required for abscission by localizing ESCRT III subunits to the cytokinetic bridge. J Cell Sci 2019; 132:jcs.226001. [PMID: 31221728 PMCID: PMC6679584 DOI: 10.1242/jcs.226001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 06/14/2019] [Indexed: 01/26/2023] Open
Abstract
Cytokinesis is the final step of cell division following chromosome segregation that generates two daughter cells. The conserved exocyst complex is required for scission of the intercellular cytokinetic bridge, although the molecular mechanisms it employs in this process are unclear. We identify and validate the early endocytic GTPase Rab5 as interacting with the exocyst complex in mammalian cells. Rab5 localizes in the cytokinetic bridge and on the midbody ring in a manner similar to the exocyst complex. Depletion of Rab5 led to delayed abscission. Caenorhabditis elegans orthologs of both exocyst complex subunits and Rab5 localize along the cleavage furrow and are required for cytokinesis in early embryos. Cytokinetic cells depleted of either Rab5 or the exocyst subunits Exoc3 and Exoc4 showed impaired deposition of the endosomal sorting complexes required for transport (ESCRT) III subunits CHMP2B and/or CHMP4B near the midbody ring. The study reveals an evolutionarily conserved role for the early endocytic marker Rab5 in cytokinetic abscission. In addition, it uncovers a key requirement of the exocyst and Rab5 for the delivery of components of the membrane-severing ESCRT III machinery to complete cytokinesis. Summary: The conserved exocytic vesicle-tethering exocyst complex and the endocytic master regulator Rab5 mutually interact and are required to deliver the ESCRT III membrane scission apparatus for completion of cytokinesis.
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Affiliation(s)
- Harsh Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Kumari Pushpa
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Amrita Kumari
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Kuldeep Verma
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Rajaiah Pergu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India .,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
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Su M, Guo EZ, Ding X, Li Y, Tarrasch JT, Brooks CL, Xu Z, Skiniotis G. Mechanism of Vps4 hexamer function revealed by cryo-EM. Sci Adv 2017; 3:e1700325. [PMID: 28439563 PMCID: PMC5392032 DOI: 10.1126/sciadv.1700325] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 02/11/2017] [Indexed: 05/08/2023]
Abstract
Vps4 is a member of AAA+ ATPase (adenosine triphosphatase associated with diverse cellular activities) that operates as an oligomer to disassemble ESCRT-III (endosomal sorting complex required for transport III) filaments, thereby catalyzing the final step in multiple ESCRT-dependent membrane remodeling events. We used electron cryo-microscopy to visualize oligomers of a hydrolysis-deficient Vps4 (vacuolar protein sorting-associated protein 4) mutant in the presence of adenosine 5'-triphosphate (ATP). We show that Vps4 subunits assemble into an asymmetric hexameric ring following an approximate helical path that sequentially stacks substrate-binding loops along the central pore. The hexamer is observed to adopt an open or closed ring configuration facilitated by major conformational changes in a single subunit. The structural transition of the mobile Vps4 subunit results in the repositioning of its substrate-binding loop from the top to the bottom of the central pore, with an associated translation of 33 Å. These structures, along with mutant-doping experiments and functional assays, provide evidence for a sequential and processive ATP hydrolysis mechanism by which Vps4 hexamers disassemble ESCRT-III filaments.
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Affiliation(s)
- Min Su
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Emily Z. Guo
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Xinqiang Ding
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yan Li
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Charles L. Brooks
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Zhaohui Xu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Corresponding author. (G.S.); (Z.X.)
| | - Georgios Skiniotis
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Corresponding author. (G.S.); (Z.X.)
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Gershony O, Pe’er T, Noach-Hirsh M, Elia N, Tzur A. Cytokinetic abscission is an acute G1 event. Cell Cycle 2014; 13:3436-41. [PMID: 25485587 PMCID: PMC4614370 DOI: 10.4161/15384101.2014.956486] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 08/11/2014] [Accepted: 08/16/2014] [Indexed: 11/19/2022] Open
Abstract
Animal cell division ends with the cutting of the microtubule and membrane intercellular bridge connecting the 2 daughter cells. This process, known as cytokinetic abscission (abscission), is widely regarded as the last step of cytokinesis, i.e., the last step of the cell cycle. Major breakthroughs have been recently achieved, illuminating mechanistic aspects of abscission; however, the timing of abscission with respect to the mammalian cell cycle remains unclear. In this study, we carefully measured the onset and progression of abscission in dividing cells expressing a G1 reporter. We conclude that abscission commences long after cells enter the G1 phase. Affiliating abscission with G1 is beyond semantics since it essentially postulates that the last step of the cell cycle is regulated in, and probably by, the following cycle.
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Affiliation(s)
- Ofir Gershony
- Department of Life Sciences and the National Institute for Biotechnology in the Negev; Ben-Gurion University; Beer-Sheva, Israel
| | - Tal Pe’er
- The Mina and Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials; Bar-Ilan University; Ramat-Gan, Israel
| | - Meirav Noach-Hirsh
- The Mina and Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials; Bar-Ilan University; Ramat-Gan, Israel
| | - Natalie Elia
- Department of Life Sciences and the National Institute for Biotechnology in the Negev; Ben-Gurion University; Beer-Sheva, Israel
| | - Amit Tzur
- The Mina and Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials; Bar-Ilan University; Ramat-Gan, Israel
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