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 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 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.

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.

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 SCAMP3 Negatively Regulates Epidermal Growth Factor Receptor Degradation and Promotes Receptor Recycling

2009 ◽  
Vol 20 (6) ◽  
pp. 1816-1832 ◽  
Author(s):  
Quyen L. Aoh ◽  
Anna M. Castle ◽  
Charles H. Hubbard ◽  
Osamu Katsumata ◽  
J. David Castle
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Multivesicular Bodies ◽  
Receptor Recycling ◽  
Endosomal Sorting ◽  
Accelerated Degradation ◽  
Early Endosomes ◽  
Epidermal Growth

The epidermal growth factor receptor (EGFR) is targeted for lysosomal degradation by ubiquitin-mediated interactions with the ESCRTs (endosomal-sorting complexes required for transport) in multivesicular bodies (MVBs). We show that secretory carrier membrane protein, SCAMP3, localizes in part to early endosomes and negatively regulates EGFR degradation through processes that involve its ubiquitylation and interactions with ESCRTs. SCAMP3 is multimonoubiquitylated and is able to associate with Nedd4 HECT ubiquitin ligases and the ESCRT-I subunit Tsg101 via its PY and PSAP motifs, respectively. SCAMP3 also associates with the ESCRT-0 subunit Hrs. Depletion of SCAMP3 in HeLa cells by inhibitory RNA accelerated degradation of EGFR and EGF while inhibiting recycling. Conversely, overexpression enhanced EGFR recycling unless ubiquitylatable lysines, PY or PSAP motifs in SCAMP3 were mutated. Notably, dual depletions of SCAMP3 and ESCRT subunits suggest that SCAMP3 has a distinct function in parallel with the ESCRTs that regulates receptor degradation. This function may affect trafficking of receptors from prelysosomal compartments as SCAMP3 depletion appeared to sustain the incidence of EGFR-containing MVBs detected by immunoelectron microscopy. Together, our results suggest that SCAMP3, its modification with ubiquitin, and its interactions with ESCRTs coordinately regulate endosomal pathways and affect the efficiency of receptor down-regulation.

scholarly journals RAB31 marks and controls an ESCRT-independent exosome pathway

Cell Research ◽  
2020 ◽  
Author(s):  
Denghui Wei ◽  
Weixiang Zhan ◽  
Ying Gao ◽  
Liyan Huang ◽  
Run Gong ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor Receptor ◽  
Gtpase Activating Protein ◽  
Endosomal Sorting ◽  
Exosome Biogenesis ◽  
Epidermal Growth ◽  
Spfh Domain ◽  
Lipid Raft Microdomains ◽  
Multivesicular Endosomes ◽  
Dual Functions

Abstract Exosomes are generated within the multivesicular endosomes (MVEs) as intraluminal vesicles (ILVs) and secreted during the fusion of MVEs with the cell membrane. The mechanisms of exosome biogenesis remain poorly explored. Here we identify that RAB31 marks and controls an ESCRT-independent exosome pathway. Active RAB31, phosphorylated by epidermal growth factor receptor (EGFR), engages flotillin proteins in lipid raft microdomains to drive EGFR entry into MVEs to form ILVs, which is independent of the ESCRT (endosomal sorting complex required for transport) machinery. Active RAB31 interacts with the SPFH domain and drives ILV formation via the Flotillin domain of flotillin proteins. Meanwhile, RAB31 recruits GTPase-activating protein TBC1D2B to inactivate RAB7, thereby preventing the fusion of MVEs with lysosomes and enabling the secretion of ILVs as exosomes. These findings establish that RAB31 has dual functions in the biogenesis of exosomes: driving ILVs formation and suppressing MVEs degradation, providing an exquisite framework to better understand exosome biogenesis.

scholarly journals Involvement of calpain-7 in epidermal growth factor receptor degradation via the endosomal sorting pathway

FEBS Journal ◽  
2014 ◽  
Vol 281 (16) ◽  
pp. 3642-3655 ◽  
Author(s):  
Yuki Maemoto ◽  
Yasuko Ono ◽  
Satomi Kiso ◽  
Hideki Shibata ◽  
Terunao Takahara ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Endosomal Sorting ◽  
Epidermal Growth
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