title: Grb10 prevents Nedd4-mediated vascular endothelial growth factor receptor-2 degradation.
abstract: One of the cellular mechanisms used to prevent continuous and enhanced activation in response to growth factors is the internalization and degradation of their receptors. Little is known about the molecular mechanisms involved in vascular endothelial growth factor receptor-2 (VEGF-R2) degradation. In a previous work, we have shown that the adaptor protein Grb10 is a positive regulator of the VEGF signaling pathway. Indeed, VEGF stimulates Grb10 expression, and Grb10 overexpression induces an increase in the amount and the tyrosine phosphorylation of VEGF-R2. In the present manuscript, we demonstrate that Grb10 stimulates VEGF-R2 expression by inhibiting the Nedd4-mediated VEGF-R2 degradation. First, we show that proteasome inhibition by MG132 induces an increase in VEGF-R2 amount, and that VEGF-R2 is ubiquitinated in response to VEGF. Expression of Nedd4, a HECT domain-containing ubiquitin ligase, induces the disappearance of VEGF-R2 in cells, suggesting that Nedd4 is involved in VEGF-R2 degradation. To determine whether Nedd4 directly ubiquitinates VEGF-R2, we expressed a ubiquitin ligase-deficient mutant Nedd4C854S. In the presence of Nedd4C854S, VEGF-R2 is expressed and ubiquitinated. These results suggest that VEGF-R2 is ubiquitinated but that Nedd4 is not involved in this process. Finally, we show that Grb10 constitutively associates with Nedd4. Co-expression of Nedd4 and Grb10 restores the expression of VEGF-R2, suggesting that Grb10 inhibits the Nedd4-mediated degradation of VEGF-R2. In this study, we show that Grb10 acts as a positive regulator in VEGF-R2 signaling and protects VEGF-R2 from degradation by interacting with Nedd4, a component of the endocytic machinery.
authors.affiliation: INSERM U145, Institut Federatif de Recherche 50, Faculte de Medecine, 06107 Nice Cedex 2, France.
authors.forename: Joseph
authors.initials: J
authors.lastname: Murdaca
authors.forename: Caroline
authors.initials: C
authors.lastname: Treins
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Monthouël-Kartmann
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Pontier-Bres
authors.forename: Sharad
authors.initials: S
authors.lastname: Kumar
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Van Obberghen
authors.forename: Sophie
authors.initials: S
authors.lastname: Giorgetti-Peraldi
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004705:Endocytosis; D056827:Endosomal Sorting Complexes Required for Transport; D004730:Endothelium, Vascular / Q000166:cytology; D051383:GRB10 Adaptor Protein; D006801:Humans; D008856:Microscopy, Fluorescence; D009154:Mutation; D000075702:Nedd4 Ubiquitin Protein Ligases; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D011506:Proteins; D012333:RNA, Messenger; D025801:Ubiquitin; D051383:GRB10 Adaptor Protein; D004247:DNA; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; D044767:Ubiquitin-Protein Ligases; D040301:Vascular Endothelial Growth Factor Receptor-2