title: Arrestin-2 interacts with the endosomal sorting complex required for transport machinery to modulate endosomal sorting of CXCR4.
abstract: The chemokine receptor CXCR4, a G protein-coupled receptor, is targeted for lysosomal degradation via a ubiquitin-dependent mechanism that involves the endosomal sorting complex required for transport (ESCRT) machinery. We have reported recently that arrestin-2 also targets CXCR4 for lysosomal degradation; however, the molecular mechanisms by which this occurs remain poorly understood. Here, we show that arrestin-2 interacts with ESCRT-0, a protein complex that recognizes and sorts ubiquitinated cargo into the degradative pathway. Signal-transducing adaptor molecule (STAM)-1, but not related STAM-2, interacts directly with arrestin-2 and colocalizes with CXCR4 on early endosomal antigen 1-positive early endosomes. Depletion of STAM-1 by RNA interference and disruption of the arrestin-2/STAM-1 interaction accelerates agonist promoted degradation of CXCR4, suggesting that STAM-1 via its interaction with arrestin-2 negatively regulates CXCR4 endosomal sorting. Interestingly, disruption of this interaction blocks agonist promoted ubiquitination of hepatocyte growth factor-regulated tyrosine kinase substrate (HRS) but not CXCR4 and STAM-1 ubiquitination. Our data suggest a mechanism whereby arrestin-2 via its interaction with STAM-1 modulates CXCR4 sorting by regulating the ubiquitination status of HRS.
authors.affiliation: Program in Molecular Biology and Department of Pharmacology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.
authors.forename: Rohit
authors.initials: R
authors.lastname: Malik
authors.forename: Adriano
authors.initials: A
authors.lastname: Marchese
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D019390:Arrestins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D019718:Receptors, CXCR4 / Q000378:metabolism*; D054875:Ubiquitination; D000071557:beta-Arrestins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D019390:Arrestins; D056827:Endosomal Sorting Complexes Required for Transport; D010750:Phosphoproteins; D019718:Receptors, CXCR4; C109775:STAM protein, human; D000071557:beta-Arrestins; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate