title: Regulation of the platelet-derived growth factor receptor-beta by G protein-coupled receptor kinase-5 in vascular smooth muscle cells involves the phosphatase Shp2.
abstract: Smooth muscle cell (SMC) proliferation and migration are substantially controlled by the platelet-derived growth factor receptor-beta (PDGFRbeta), which can be regulated by the Ser/Thr kinase G protein-coupled receptor kinase-2 (GRK2). In mouse aortic SMCs, however, we found that prolonged PDGFRbeta activation engendered down-regulation of GRK5, but not GRK2; moreover, GRK5 and PDGFRbeta were coordinately up-regulated in SMCs from atherosclerotic arteries. With SMCs from GRK5 knock-out and cognate wild type mice (five of each), we found that physiologic expression of GRK5 increased PDGF-promoted PDGFRbeta seryl phosphorylation by 3-fold and reduced PDGFRbeta-promoted phosphoinositide hydrolysis, thymidine incorporation, and overall PDGFRbeta tyrosyl phosphorylation by approximately 35%. Physiologic SMC GRK5 activity also increased PDGFRbeta association with the phosphatase Shp2 (8-fold), enhanced phosphorylation of PDGFRbeta Tyr(1009) (the docking site for Shp2), and reduced phosphorylation of PDGFRbeta Tyr(1021). Consistent with having increased PDGFRbeta-associated Shp2 activity, GRK5-expressing SMCs demonstrated greater PDGF-induced Src activation than GRK5-null cells. GRK5-mediated desensitization of PDGFRbeta inositol phosphate signaling was diminished by Shp2 knock-down or impairment of PDGFRbeta/Shp2 association. In contrast to GRK5, physiologic GRK2 activity did not alter PDGFRbeta/Shp2 association. Finally, purified GRK5 effected agonist-dependent seryl phosphorylation of partially purified PDGFRbetas. We conclude that GRK5 mediates the preponderance of PDGF-promoted seryl phosphorylation of the PDGFRbeta in SMCs, and, through mechanisms involving Shp2, desensitizes PDGFRbeta inositol phosphate signaling and enhances PDGFRbeta-triggered Src activation.
authors.affiliation: Department of Medicine (Cardiology), Duke University, Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Jiao-Hui
authors.initials: JH
authors.lastname: Wu
authors.forename: Robi
authors.initials: R
authors.lastname: Goswami
authors.forename: Xinjiang
authors.initials: X
authors.lastname: Cai
authors.forename: Sabrina T
authors.initials: ST
authors.lastname: Exum
authors.forename: Xuewei
authors.initials: X
authors.lastname: Huang
authors.forename: Lisheng
authors.initials: L
authors.lastname: Zhang
authors.forename: Leigh
authors.initials: L
authors.lastname: Brian
authors.forename: Richard T
authors.initials: RT
authors.lastname: Premont
authors.forename: Karsten
authors.initials: K
authors.lastname: Peppel
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Freedman
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D054774:G-Protein-Coupled Receptor Kinase 5; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D011817:Rabbits; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D020797:Receptor, Platelet-Derived Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D054774:G-Protein-Coupled Receptor Kinase 5; C517898:GRK5 protein, human; C517895:Grk5 protein, mouse; C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse