title: Cbl-mediated ubiquitinylation is required for lysosomal sorting of epidermal growth factor receptor but is dispensable for endocytosis.
abstract: Ligand-induced down-regulation controls the signaling potency of the epidermal growth factor receptor (EGFR/ErbB1). Overexpression studies have identified Cbl-mediated ubiquitinylation of EGFR as a mechanism of ligand-induced EGFR down-regulation. However, the role of endogenous Cbl in EGFR down-regulation and the precise step in the endocytic pathway regulated by Cbl remain unclear. Using Cbl-/- mouse embryonic fibroblast cell lines, we demonstrate that endogenous Cbl is essential for ligand-induced ubiquitinylation and efficient degradation of EGFR. Further analyses using Chinese hamster ovary cells with a temperature-sensitive defect in ubiquitinylation confirm a crucial role of the ubiquitin machinery in Cbl-mediated EGFR degradation. However, internalization into early endosomes did not require Cbl function or an intact ubiquitin pathway. Confocal immunolocalization studies indicated that Cbl-dependent ubiquitinylation plays a critical role at the early endosome to late endosome/lysosome sorting step of EGFR down-regulation. These findings establish Cbl as the major endogenous ubiquitin ligase responsible for EGFR degradation, and show that the critical role of Cbl-mediated ubiquitinylation is at the level of endosomal sorting, rather than at the level of internalization.
authors.affiliation: Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Duan
authors.forename: Yuko
authors.initials: Y
authors.lastname: Miura
authors.forename: Manjari
authors.initials: M
authors.lastname: Dimri
authors.forename: Biswanath
authors.initials: B
authors.lastname: Majumder
authors.forename: Ingrid L
authors.initials: IL
authors.lastname: Dodge
authors.forename: Alagarsamy L
authors.initials: AL
authors.lastname: Reddi
authors.forename: Amiya
authors.initials: A
authors.lastname: Ghosh
authors.forename: Norvin
authors.initials: N
authors.lastname: Fernandes
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Zhou
authors.forename: Karen
authors.initials: K
authors.lastname: Mullane-Robinson
authors.forename: Navin
authors.initials: N
authors.lastname: Rao
authors.forename: Stephen
authors.initials: S
authors.lastname: Donoghue
authors.forename: Rick A
authors.initials: RA
authors.lastname: Rogers
authors.forename: David
authors.initials: D
authors.lastname: Bowtell
authors.forename: Mayumi
authors.initials: M
authors.lastname: Naramura
authors.forename: Hua
authors.initials: H
authors.lastname: Gu
authors.forename: Vimla
authors.initials: V
authors.lastname: Band
authors.forename: Hamid
authors.initials: H
authors.lastname: Band
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D015536:Down-Regulation; D004622:Embryo, Mammalian; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D050722:Oncogene Protein v-cbl; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D050721:Proto-Oncogene Proteins c-cbl; D012333:RNA, Messenger / Q000032:analysis; D015682:Retroviridae Proteins, Oncogenic / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D013696:Temperature; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
chemical_list: D050722:Oncogene Protein v-cbl; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D015682:Retroviridae Proteins, Oncogenic; D025801:Ubiquitin; D004815:Epidermal Growth Factor; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D066246:ErbB Receptors; C067419:CBL protein, human; C493849:Cbl protein, mouse