Biology subjects

Martin-Serrano, J.

Publications and source records attributed to Martin-Serrano, J..

3 recordsLinked to original sources

bioRxiv2020

Vaccinia virus hijacks ESCRT-mediated multivesicular body formation for virus egress

Unlike most enveloped viruses, poxvirus egress is a complex process whereby cytoplasmic single membrane-bound virions are wrapped in a cell-derived double membrane. These triple membrane-bound particles, termed intracellular enveloped virions (IEVs), are then released from infected cells by fusion. While the wrapping double membrane is thought to be derived from virus-modified trans-Golgi or early endosomal cisternae, the cellular factors that regulate virus wrapping remain largely undefined. To identify novel cell factors required for this process the prototypic poxvirus, vaccinia virus (VACV), was subjected to a high-throughput RNAi screen directed against cellular membrane trafficking proteins. Focusing on the endosomal sorting complexes required for transport (ESCRT), we demonstrate that ESCRT-III and VPS4 are required for packaging of virus into multivesicular bodies (MVBs). EM-based characterization of these MVB-IEVs showed that they account for half of IEV production indicating that MVBs serve as a second major source of VACV wrapping membrane. These data support a model whereby, in addition to cisternae-based wrapping, VACV hijacks ESCRT-mediated MVB formation to facilitate virus egress and spread.

cell biology↗

bioRxiv2019

Midbody remnant inheritance is regulated by the ESCRT subunit CHMP4C

The inheritance of the midbody remnant (MBR) breaks the symmetry of the two daughter cells, with functional consequences for lumen and primary cilium formation by polarized epithelial cells, and also for development and differentiation. However, despite their importance, neither the relationship between the plasma membrane and the inherited MBR nor the mechanism of MBR inheritance is well known. Here, the analysis by correlative light and ultra-high-resolution scanning electron microscopy reveals a membranous stalk that physically connects the MBR to the apical membrane of epithelial cells. The stalk, which derives from the uncleaved side of the midbody, concentrates the ESCRT machinery. The ESCRT CHMP4C subunit enables MBR inheritance, and its depletion dramatically reduces the percentage of ciliated cells. We demonstrate: (1) that MBRs are physically connected to the plasma membrane, (2) how CHMP4C helps maintain the integrity of the connection, and (3) the functional importance of the connection.

cell biology↗

bioRxiv2018

A cancer-associated polymorphism in ESCRT-III disrupts the abscission checkpoint and promotes genome instability

Cytokinetic abscission facilitates the irreversible separation of daughter cells. This process requires the Endosomal Sorting Complexes Required for Transport (ESCRT) machinery and is tightly regulated by Charged Multivesicular body Protein 4C (CHMP4C), an ESCRT-III subunit that engages the abscission checkpoint (NoCut) in response to mitotic problems such as persisting chromatin bridges within the midbody. Importantly, a human polymorphism in CHMP4CT232 (rs35094336), increases cancer susceptibility. Here, we explain the structural and functional basis for this cancer association: the CHMP4CT232 allele unwinds the C-terminal helix of CHMP4C, impairs binding to the early-acting ESCRT factor ALIX, and disrupts the abscission checkpoint. Cells expressing CHMP4CT232 exhibit increased levels of DNA damage and are sensitized to several conditions that increase chromosome mis-segregation, including DNA replication stress, inhibition of the mitotic checkpoint, and loss of p53. Our data demonstrate the biological importance of the abscission checkpoint, and suggest that dysregulation of abscission by CHMP4CT232 may synergize with oncogene-induced mitotic stress to promote genomic instability and tumorigenesis.\n\nSignificance StatementThe final step of cell division, abscission, is temporally regulated by the Aurora B kinase and CHMP4C in a conserved pathway called the abscission checkpoint which arrests abscission in the presence of lingering mitotic problems. Despite extensive study, the physiological importance of this pathway to human health has remained elusive. We now demonstrate that a cancer predisposing polymorphism in CHMP4C disrupts the abscission checkpoint and results in DNA damage accumulation. Moreover, deficits in this checkpoint synergize with p53 loss and generate aneuploidy under stress conditions that increase the frequency of chromosome missegregation. Therefore, cells expressing the cancer-associated polymorphism in CHMP4C are genetically unstable, thus suggesting a novel oncogenic mechanism that may involve the dysregulation of abscission.

cell biology↗