title: Phosphoproteomic analysis of AT1 receptor-mediated signaling responses in proximal tubules of angiotensin II-induced hypertensive rats.
abstract: The signaling mechanisms underlying the effects of angiotensin II in proximal tubules of the kidney are not completely understood. Here we measured signal protein phosphorylation in isolated proximal tubules using pathway-specific proteomic analysis in rats continuously infused with pressor or non-pressor doses of angiotensin II over a 2-week period. Of the 38 phosphoproteins profiled, 14 were significantly altered by the pressor dose. This included increased phosphorylation of the protein kinase C isoenzymes, PKCα and PKCβII, and the glycogen synthase kinases, GSK3α and GSK3β. Phosphorylation of the cAMP-response element binding protein 1 and PKCδ were decreased, whereas PKCɛ remained unchanged. By contrast, the phosphorylation of only seven proteins was altered by the non-pressor dose, which increased that of PKCα, PKCδ, and GSKα. Phosphorylation of MAP kinases, ERK1/2, was not increased in proximal tubules in vivo by the pressor dose, but was in proximal tubule cells in vitro. Infusion of the pressor dose decreased, whereas the non-pressor dose of angiotensin II increased the phosphorylation of the sodium and hydrogen exchanger 3 (NHE-3) in membrane fractions of proximal tubules. Losartan largely blocked the signaling responses induced by the pressor dose. Thus, PKCα and PKCβII, GSK3α and GSK3β, and cAMP-dependent signaling pathways may have important roles in regulating proximal tubular sodium and fluid transport in Ang II-induced hypertensive rats.
authors.affiliation: Laboratory of Receptor and Signal Transduction, Department of Pharmacology and Toxicology, The University of Mississippi Medical Center, 1500 North State Street, Jackson, MS 39216, USA.
authors.forename: Xiao C
authors.initials: XC
authors.lastname: Li
authors.forename: Jia L
authors.initials: JL
authors.lastname: Zhuo
mesh_terms: D000804:Angiotensin II / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D005796:Genes; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D019808:Losartan / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D051379:Mice; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; C508137:Creb1 protein, rat; D017362:Cyclic AMP Response Element-Binding Protein; D010750:Phosphoproteins; D044140:Receptor, Angiotensin, Type 1; C000613386:Slc9a3 protein, mouse; C000613387:Slc9a3 protein, rat; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D000804:Angiotensin II; D000242:Cyclic AMP; D051571:Protein Kinase C-alpha; D038362:Glycogen Synthase Kinase 3; D019808:Losartan