scholarly journals VPS37A directs ESCRT recruitment for phagophore closure

2019 ◽  
Vol 218 (10) ◽  
pp. 3336-3354 ◽  
Author(s):  
Yoshinori Takahashi ◽  
Xinwen Liang ◽  
Tatsuya Hattori ◽  
Zhenyuan Tang ◽  
Haiyan He ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Growth Factor Receptor ◽  
Multivesicular Body ◽  
Regulatory Mechanisms ◽  
Endosomal Sorting ◽  
Aaa Atpase ◽  
Escrt Machinery ◽  
Genome Wide ◽  
A Genome ◽  
Epidermal Growth

The process of phagophore closure requires the endosomal sorting complex required for transport III (ESCRT-III) subunit CHMP2A and the AAA ATPase VPS4, but their regulatory mechanisms remain unknown. Here, we establish a FACS-based HaloTag-LC3 autophagosome completion assay to screen a genome-wide CRISPR library and identify the ESCRT-I subunit VPS37A as a critical component for phagophore closure. VPS37A localizes on the phagophore through the N-terminal putative ubiquitin E2 variant domain, which is found to be required for autophagosome completion but dispensable for ESCRT-I complex formation and the degradation of epidermal growth factor receptor in the multivesicular body pathway. Notably, loss of VPS37A abrogates the phagophore recruitment of the ESCRT-I subunit VPS28 and CHMP2A, whereas inhibition of membrane closure by CHMP2A depletion or VPS4 inhibition accumulates VPS37A on the phagophore. These observations suggest that VPS37A coordinates the recruitment of a unique set of ESCRT machinery components for phagophore closure in mammalian cells.

The relationship between ER–multivesicular body membrane contacts and the ESCRT machinery

2012 ◽  
Vol 40 (2) ◽  
pp. 464-468 ◽  
Author(s):  
Emily R. Eden ◽  
Thomas Burgoyne ◽  
James R. Edgar ◽  
Alexander Sorkin ◽  
Clare E. Futter
Keyword(s):  
Catalytic Domain ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Multivesicular Body ◽  
Endosomal Sorting ◽  
Membrane Contact Sites ◽  
Escrt Machinery ◽  
Membrane Contacts ◽  
Epidermal Growth ◽  
The Relationship

Activated EGFR (epidermal growth factor receptor) undergoes ESCRT (endosomal sorting complex required for transport)-mediated sorting on to ILVs (intraluminal vesicles) of endosomes before degradation in the lysosome. Sorting of endocytosed EGFR on to ILVs removes the catalytic domain of the EGFR from the cytoplasm, resulting in termination of receptor signalling. EGFR signalling is also subject to down-regulation through receptor dephosphorylation by the ER (endoplasmic reticulum)-localized PTP1B (protein tyrosine phosphatase 1B). PTP1B on the cytoplasmic face of the ER interacts with endocytosed EGFR via direct membrane contacts sites between the ER and endosomes. In the present paper, we review the relationship between ER–endosome membrane contact sites and ILV formation, and their potential role in the regulation of EGFR sorting on to ILVs, through PTP1B-mediated dephosphorylation of both EGFR and components of the ESCRT machinery.

scholarly journals Distinct Roles for Tsg101 and Hrs in Multivesicular Body Formation and Inward Vesiculation

2006 ◽  
Vol 17 (8) ◽  
pp. 3469-3483 ◽  
Author(s):  
M. Razi ◽  
C. E. Futter
Keyword(s):  
Growth Factor ◽  
Mammalian Cells ◽  
Susceptibility Gene ◽  
Growth Factor Receptor ◽  
Multivesicular Body ◽  
Early Endosome ◽  
Endosomal Sorting ◽  
Epidermal Growth ◽  
Tumor Susceptibility Gene ◽  
Hepatocyte Growth

In mammalian cells, epidermal growth factor (EGF) stimulation promotes multivesicular body (MVB) formation and inward vesiculation within MVB. Annexin 1 is required for EGF-stimulated inward vesiculation but not MVB formation, demonstrating that MVB formation (the number of MVBs/unit cytoplasm) and inward vesiculation (the number of internal vesicles/MVB) are regulated by different mechanisms. Here, we show that EGF-stimulated MVB formation requires the tumor susceptibility gene, Tsg101, a component of the ESCRT (endosomal sorting complex required for transport) machinery. Depletion of Tsg101 potently inhibits EGF degradation and MVB formation and causes the vacuolar domains of the early endosome to tubulate. Although Tsg101 depletion inhibits MVB formation and alters the morphology of the early endosome in unstimulated cells, these effects are much greater after EGF stimulation. In contrast, depletion of hepatocyte growth factor receptor substrate (Hrs) only modestly inhibits EGF degradation, does not induce tubulation of the early endosome, and causes the generation of enlarged MVBs that retain the ability to fuse with the lysosome. Together, these results indicate that Tsg101 is required for the formation of stable vacuolar domains within the early endosome that develop into MVBs and Hrs is required for the accumulation of internal vesicles within MVBs and that both these processes are up-regulated by EGF stimulation.

scholarly journals Trafficking defects in WASH-knockout fibroblasts originate from collapsed endosomal and lysosomal networks

2012 ◽  
Vol 23 (16) ◽  
pp. 3215-3228 ◽  
Author(s):  
Timothy S. Gomez ◽  
Jacquelyn A. Gorman ◽  
Amaia Artal-Martinez de Narvajas ◽  
Alexander O. Koenig ◽  
Daniel D. Billadeau
Keyword(s):  
Mammalian Cells ◽  
Cellular Localization ◽  
Growth Factor Receptor ◽  
Membrane Domains ◽  
Filamentous Actin ◽  
Endosomal Sorting ◽  
Associated Proteins ◽  
Epidermal Growth ◽  
Trafficking Defects ◽  
Syndrome Protein

The Arp2/3-activator Wiskott–Aldrich syndrome protein and Scar homologue (WASH) is suggested to regulate actin-dependent membrane scission during endosomal sorting, but its cellular roles have not been fully elucidated. To investigate WASH function, we generated tamoxifen-inducible WASH-knockout mouse embryonic fibroblasts (WASHout MEFs). Of interest, although EEA1+ endosomes were enlarged, collapsed, and devoid of filamentous-actin and Arp2/3 in WASHout MEFs, we did not observe elongated membrane tubules emanating from these disorganized endomembranes. However, collapsed WASHout endosomes harbored segregated subdomains, containing either retromer cargo recognition complex–associated proteins or EEA1. In addition, we observed global collapse of LAMP1+ lysosomes, with some lysosomal membrane domains associated with endosomes. Both epidermal growth factor receptor (EGFR) and transferrin receptor (TfnR) exhibited changes in steady-state cellular localization. EGFR was directed to the lysosomal compartment and exhibited reduced basal levels in WASHout MEFs. However, although TfnR was accumulated with collapsed endosomes, it recycled normally. Moreover, EGF stimulation led to efficient EGFR degradation within enlarged lysosomal structures. These results are consistent with the idea that discrete receptors differentially traffic via WASH-dependent and WASH-independent mechanisms and demonstrate that WASH-mediated F-actin is requisite for the integrity of both endosomal and lysosomal networks in mammalian cells.

scholarly journals Essential Role of hIST1 in Cytokinesis

2009 ◽  
Vol 20 (5) ◽  
pp. 1374-1387 ◽  
Author(s):  
Monica Agromayor ◽  
Jez G. Carlton ◽  
John P. Phelan ◽  
Daniel R. Matthews ◽  
Leo M. Carlin ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Multivesicular Body ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Membrane Fission ◽  
Immunodeficiency Virus ◽  
Positive Modulator ◽  
Essential Function ◽  
Hiv 1

The last steps of multivesicular body (MVB) formation, human immunodeficiency virus (HIV)-1 budding and cytokinesis require a functional endosomal sorting complex required for transport (ESCRT) machinery to facilitate topologically equivalent membrane fission events. Increased sodium tolerance (IST) 1, a new positive modulator of the ESCRT pathway, has been described recently, but an essential function of this highly conserved protein has not been identified. Here, we describe the previously uncharacterized KIAA0174 as the human homologue of IST1 (hIST1), and we report its conserved interaction with VPS4, CHMP1A/B, and LIP5. We also identify a microtubule interacting and transport (MIT) domain interacting motif (MIM) in hIST1 that is necessary for its interaction with VPS4, LIP5 and other MIT domain-containing proteins, namely, MITD1, AMSH, UBPY, and Spastin. Importantly, hIST1 is essential for cytokinesis in mammalian cells but not for HIV-1 budding, thus providing a novel mechanism of functional diversification of the ESCRT machinery. Last, we show that the hIST1 MIM activity is essential for cytokinesis, suggesting possible mechanisms to explain the role of hIST1 in the last step of mammalian cell division.

ESCRT proteins, endosome organization and mitogenic receptor down-regulation

2009 ◽  
Vol 37 (1) ◽  
pp. 146-150 ◽  
Author(s):  
Philip Woodman
Keyword(s):  
Growth Factor Receptor ◽  
Multivesicular Body ◽  
Early Endosome ◽  
Tyrosine Kinase Receptors ◽  
Physical Separation ◽  
Endosomal Sorting ◽  
Associated Proteins ◽  
Epidermal Growth ◽  
Detailed Function ◽  
Subsequent Incorporation

Mitogenic tyrosine kinase receptors such as the EGFR (epidermal growth factor receptor) are endocytosed once they are activated at the cell surface. After reaching the early endosome, they are ubiquitinated within their cytosolic domain and are consequently sorted away from recycling receptors. They are then incorporated into intraluminal vesicles within the MVB (multivesicular body) en route to the lysosome, where they are degraded. MVB formation requires the stabilization of the vacuolar domain of the early endosome, the segregation of degradative cargo within this domain (with subsequent incorporation of receptors such as EGFR into intraluminal vesicles) and the physical separation and movement of this domain away from the tubular regions of the early endosome. How these different aspects of MVB biogenesis are coupled is unknown, but ESCRTs (endosomal sorting complexes required for transport) have been identified as key molecular players in driving mitogenic receptor sequestration and formation of intraluminal vesicles. The present review summarizes recent findings within the field and from our laboratory regarding the detailed function of ESCRTs and associated proteins in driving the ubiquitin-dependent sorting of EGFR and in maintaining the domain organization of the early endosome.

scholarly journals The secreted Salmonella dublin phosphoinositide phosphatase, SopB, localizes to PtdIns(3)P-containing endosomes and perturbs normal endosome to lysosome trafficking

2006 ◽  
Vol 395 (2) ◽  
pp. 239-247 ◽  
Author(s):  
Joseph D. Dukes ◽  
Huailo Lee ◽  
Rachel Hagen ◽  
Barbara J. Reaves ◽  
Abigail N. Layton ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Growth Factor Receptor ◽  
Secretion Systems ◽  
Endosomal Sorting ◽  
Salmonella Dublin ◽  
Phosphoinositide Phosphatase ◽  
Type Iii Secretion Systems ◽  
Epidermal Growth

Invasion and survival in mammalian cells by Salmonella enterica is mediated by bacterial proteins that are delivered to the host cell cytoplasm by type III secretion systems. One of these proteins, SopB/SigD, is a phosphoinositide phosphatase that can hydrolyse a number of substrates in vitro including PtdIns(3,5)P2. These substrates are, however, likely to be restricted in vivo by the localization of SopB, as different phosphoinositides have distinct spatial distributions in mammalian cells. In the present study, we show that heterologously expressed SopB localizes almost exclusively to endosomes containing the lipid PtdIns(3)P, and on which ESCRT (endosomal sorting complexes required for transport) proteins assemble. Furthermore, we present evidence that SopB can inhibit trafficking of activated epidermal growth factor receptor to the lysosome. These results provide further evidence that PtdIns(3,5)P2, a lipid involved in endosomal maturation, may be a relevant in vivo substrate of SopB. We hypothesize that reduction of PtdIns(3,5)P2 levels in cells by the action of SopB may perturb the function of a subset of ESCRT proteins that have previously been shown to bind to this lipid.

scholarly journals Regulatory Mechanisms of Metamorphic Neuronal Remodeling Revealed Through a Genome-Wide Modifier Screen in Drosophila melanogaster

Genetics ◽  
2017 ◽  
Vol 206 (3) ◽  
pp. 1429-1443 ◽  
Author(s):  
Dahong Chen ◽  
Tingting Gu ◽  
Tom N. Pham ◽  
Montgomery J. Zachary ◽  
Randall S. Hewes
Keyword(s):  
Drosophila Melanogaster ◽  
Regulatory Mechanisms ◽  
Neuronal Remodeling ◽  
Genome Wide ◽  
A Genome

An epidermal growth factor receptor/ret chimera generates mitogenic and transforming signals: evidence for a ret-specific signaling pathway

1994 ◽  
Vol 14 (1) ◽  
pp. 663-675
Author(s):  
M Santoro ◽  
W T Wong ◽  
P Aroca ◽  
E Santos ◽  
B Matoskova ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinases ◽  
Mammalian Cells ◽  
Egf Receptor ◽  
Biological Effects ◽  
Ectopic Expression ◽  
Growth Factor Receptor ◽  
Dependent Signal ◽  
Epidermal Growth

A chimeric expression vector which encoded for a molecule encompassing the extracellular domain of the epidermal growth factor (EGF) receptor (EGFR) and the intracellular domain of the ret kinase (EGFR/ret chimera) was generated. Upon ectopic expression in mammalian cells, the EGFR/ret chimera was correctly synthesized and transported to the cell surface, where it was shown capable of binding EGF and transducing an EGF-dependent signal intracellularly. Thus, the EGFR/ret chimera allows us to study the biological effects and biochemical activities of the ret kinase under controlled conditions of activation. Comparative analysis of the growth-promoting activity of the EGFR/ret chimera expressed in fibroblastic or hematopoietic cells revealed a biological phenotype clearly distinguishable from that of the EGFR, indicating that the two kinases couple with mitogenic pathways which are different to some extent. Analysis of biochemical pathways implicated in the transduction of mitogenic signals also evidenced significant differences between the ret kinase and other receptor tyrosine kinases. Thus, the sum of our results indicates the existence of a ret-specific pathway of mitogenic signaling.

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