Hrs is a positive regulator of VEGF and insulin signaling.
Both VEGF and insulin are implicated in the pathogenesis of diabetic retinopathy. While it has been established for many years that the number of cell surface receptors impacts upon VEGF and insulin action, little is known about the precise machinery and proteins driving VEGF-R2 and IR degradation. Here, we investigate the role of Hepatocyte growth factor-Regulated tyrosine kinase Substrate (Hrs), a regulator of RTK trafficking, in VEGF and insulin signaling. We report that ectopic expression of Hrs increases VEGF-R2 and IR number and tyrosine phosphorylation, leading to amplification of their downstream signaling. The UIM (Ubiquitin Interacting Motif) domain of Hrs is required for Hrs-induced increases in VEGF-R2, but not in IR. Furthermore, Hrs is tyrosine-phosphorylated in response to VEGF and insulin. We show that the UIM domain is required for Hrs phosphorylation in response to VEGF, but not to insulin. Importantly, Hrs co-localizes with both VEGF-R2 and IR and co-immunoprecipitates with both in a manner independent of the Hrs-UIM domain. Finally, we demonstrate that Hrs inhibits Nedd4-mediated VEGF-R2 degradation and acts additively with Grb10. We conclude that Hrs is a positive regulator of VEGF-R2 and IR signaling and that ectopic expression of Hrs protects both VEGF-R2 and IR from degradation.
Hasseine
Larbi Kamal
LK
INSERM, U145, F-06107 Nice, France.
Murdaca
Joseph
J
Suavet
Florence
F
Longnus
Sarah
S
Giorgetti-Peraldi
Sophie
S
Van Obberghen
Emmanuel
E
D001665:Binding Sites / Q000502:physiology; D002460:Cell Line; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000503:physiopathology; D056827:Endosomal Sorting Complexes Required for Transport; D051383:GRB10 Adaptor Protein / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000075702:Nedd4 Ubiquitin Protein Ligases; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000502:physiology; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
D056827:Endosomal Sorting Complexes Required for Transport; C096358:GRB10 protein, human; D007328:Insulin; D010750:Phosphoproteins; D025801:Ubiquitin; D042461:Vascular Endothelial Growth Factor A; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate; D051383:GRB10 Adaptor Protein; D014443:Tyrosine; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; D044767:Ubiquitin-Protein Ligases; D011972:Receptor, Insulin; D040301:Vascular Endothelial Growth Factor Receptor-2