TSG101 interaction with HRS mediates endosomal trafficking and receptor down-regulation

Abstract

Down-regulation of mitogenic signaling in mammalian cells relies in part on endosomal trafficking of activated receptors into lysosomes, where the receptors are degraded. These events are mediated by ubiquitination of the endosomal cargo and its consequent sorting into multivesicular bodies that form at the surfaces of late endosomes. Tumor susceptibility gene 101 (tsg101) recently was found to be centrally involved in this process. Here we report that TSG101 interacts with hepatocyte growth factor-regulated tyrosine kinase substrate (HRS), an early endosomal protein, and that disruption of this interaction impedes endosomal trafficking and endocytosis-mediated degradation of mitogenic receptors. TSG101͞HRS interaction occurs between a ubiquitin-binding domain of TSG101 and two distinct proline-rich regions of HRS, and is modulated by a C-terminal TSG101 sequence that resembles a motif targeted in HRS. Mutational perturbation of TSG101͞HRS interaction prevented delivery of epidermal growth factor receptor (EGFR) to late endosomes, resulted in the cellular accumulation of ubiquitinated EGFR in early endosomes, and inhibited ligandinduced down-regulation of EGFR. Our results reveal the TSG101 interaction with HRS as a crucial step in endocytic down-regulation of mitogenic signaling and suggest a role for this interaction in linking the functions of early and late endosomes.epidermal growth factor receptor ͉ endocytosis ͉ multivesicular body ͉ endosomes

ESCRT-I Component VPS23A Affects ABA Signaling by Recognizing ABA Receptors for Endosomal Degradation

“…The UEV domain of Vps23p/TSG101 can interact simultaneously with ubiquitin and the P(S/T)xP motif of Vps27p/Hrs (Bilodeau et al,2003;Katzmann et al, 2003;Lu et al, 2003).…”

Regulation of Epidermal Growth Factor Receptor Down-Regulation by UBPY-mediated Deubiquitination at Endosomes

“…On transport from the cell surface to endosomes, ubiquitinated EGFR is recognized by the Hrs-STAM complex. EGFR is then transferred to endosomal sorting complex required for transport (ESCRT)-I, a protein complex that also binds to ubiquitinated cargo proteins and sorts them into MVB lumenal vesicles in collaboration with ESCRT-II and ESCRT-III (Katzmann et al, 2001Bache et al, 2003a;Lu et al, 2003; Figure 8, route A). However, a certain proportion of EGFR is transferred to UBPY from the Hrs-STAM complex instead, via transient interaction between STAM and UBPY (Figure 8, route B).…”

“…Depletion of Hrs or STAM using RNA interference (RNAi) or gene disruption inhibits RTK down-regulation in mammalian cells (Bache et al, 2003b;Hammond et al, 2003;Kanazawa et al, 2003;Lu et al, 2003) and in Drosophila (Lloyd et al, 2002). The budding yeast Saccharomyces cerevisiae also has orthologues of Hrs and STAM, which are Vps27 (vacuolar protein sorting 27) and Hse1 (Hbp/STAM/EAST 1), respectively.…”

Ubiquitinylation of Igβ Dictates the Endocytic Fate of the B Cell Antigen Receptor

“…Receptors labeled with single ubiquitin (Ub) molecules are recognized in early endosomes by Hrs/Vps27p and ESCRT I complexes which sort receptors toward late endosomes (10). At the limiting membrane of targeted vesicles, components of the ESCRT II/III complex (11,12) segregate ubiquitinylated molecules into IMBs (13,14). In some cases ubiquitinylation of receptors, or of components of the endocytic machinery, can initiate sorting into clathrin-coated pits and receptor endocytosis (15,16).…”