title: Angiotensin II inhibits activity of human organic anion transporter 3 through activation of protein kinase Calpha: accelerating endocytosis of the transporter.
abstract: Human organic anion transporter 3 (hOAT3) belongs to a family of organic anion transporters that play critical roles in the body disposition of numerous clinically important drugs. In the kidney, hOAT3 functions through a tertiary transport mechanism involving two other membrane proteins Na/K-ATPase and Na-dicarboxylate cotransporter. In the current study, we established COS-7 cells stably expressing hOAT3 and examined the regulation of hOAT3 by protein kinase C (PKC) and angiotensin II. Both PKC activation and angiotensin II inhibited hOAT3 transport activity. Angiotensin II induced inhibition of hOAT3 activity could be prevented by treating hOAT3-expressing cells with staurosporine, a general inhibitor for PKC, and with Gö6976 (5,6,7,13-Tetrahydro-13-methyl-5-oxo-12H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-12-propanenitrile), a PKCalpha-specific inhibitor. Examination of hOAT3 expression and transport kinetics revealed that angiotensin II induced inhibition of hOAT3 activity mainly resulted from a decreased cell surface expression kinetically reflected as a decreased V(max) without a significant change in K(m). Such angiotensin II induced decrease in cell surface expression of hOAT3 was caused by an increase in hOAT3 endocytosis. However, angiotensin II induced endocytosis of Na/K-ATPase did not occur under such condition. We concluded that angiotensin II inhibited hOAT3 activity through the activation of PKCalpha, which led to an acceleration of hOAT3 endocytosis.
authors.affiliation: Department of Pharmaceutics, Rutgers, The State University of New Jersey, United States.
authors.forename: Peng
authors.initials: P
authors.lastname: Duan
authors.forename: Shanshan
authors.initials: S
authors.lastname: Li
authors.forename: Guofeng
authors.initials: G
authors.lastname: You
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004705:Endocytosis / Q000187:drug effects*; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D029362:Organic Anion Transporters, Sodium-Independent / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D051571:Protein Kinase C-alpha / Q000378:metabolism*
chemical_list: D029362:Organic Anion Transporters, Sodium-Independent; C114338:organic anion transport protein 3; D000804:Angiotensin II; D051571:Protein Kinase C-alpha