Teiko Ohashi1,2, Keiko Uchida3, Shinichi Uchida2, Sei Sasaki2, Kosaku Nitta1. 1. Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjyuku-ku, Tokyo, 162-8666, Japan. 2. Department of Nephrology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo, 113-8519, Japan. 3. Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjyuku-ku, Tokyo, 162-8666, Japan. kuchida@kc.twmu.ac.jp.
Abstract
BACKGROUND: We reported that nephrin is phosphorylated at Y1204 and Y1228 under normal conditions and that the phosphorylation is decreased in puromycin nephrosis and in human minimal change nephrosis. These results indicate that the phosphorylation of nephrin is important for maintaining normal podocyte function. However, little is known about the regulation of nephrin phosphorylation. Here, we investigated whether glucocorticoid, a drug used to treat glomerular diseases with proteinuria, might affect the phosphorylation of nephrin. METHODS: Human cultured podocytes transiently expressing human nephrin were treated with dexamethasone (Dex), and the phosphorylation of nephrin was determined by immunoblot with the anti-pY1228 antibody. RESULTS: Dex treatment for 24 h increased the phosphorylation of nephrin; this increased phosphorylation was inhibited by the glucocorticoid receptor antagonist but not by the mineral corticoid receptor antagonist. A shorter incubation time (30 min) did not increase the phosphorylation, and actinomycin D and cycloheximide treatments abolished the increased phosphorylation. The activation of Src-family kinases was correlated with nephrin phosphorylation, both of which were abolished by small interfering RNA (siRNA) treatment for serum/glucocorticoid-induced kinase 1 (SGK1). CONCLUSIONS: These results clarify a novel action of glucocorticoid on nephrin phosphorylation through SGK1. Glucocorticoid treatment for human glomerulonephritis may exert its function by regulating the phosphorylation of nephrin.
BACKGROUND: We reported that nephrin is phosphorylated at Y1204 and Y1228 under normal conditions and that the phosphorylation is decreased in puromycinnephrosis and in human minimal change nephrosis. These results indicate that the phosphorylation of nephrin is important for maintaining normal podocyte function. However, little is known about the regulation of nephrin phosphorylation. Here, we investigated whether glucocorticoid, a drug used to treat glomerular diseases with proteinuria, might affect the phosphorylation of nephrin. METHODS:Human cultured podocytes transiently expressing humannephrin were treated with dexamethasone (Dex), and the phosphorylation of nephrin was determined by immunoblot with the anti-pY1228 antibody. RESULTS:Dex treatment for 24 h increased the phosphorylation of nephrin; this increased phosphorylation was inhibited by the glucocorticoid receptor antagonist but not by the mineral corticoid receptor antagonist. A shorter incubation time (30 min) did not increase the phosphorylation, and actinomycin D and cycloheximide treatments abolished the increased phosphorylation. The activation of Src-family kinases was correlated with nephrin phosphorylation, both of which were abolished by small interfering RNA (siRNA) treatment for serum/glucocorticoid-induced kinase 1 (SGK1). CONCLUSIONS: These results clarify a novel action of glucocorticoid on nephrin phosphorylation through SGK1. Glucocorticoid treatment for humanglomerulonephritis may exert its function by regulating the phosphorylation of nephrin.
Authors: Nina Jones; Laura A New; Megan A Fortino; Vera Eremina; Julie Ruston; Ivan M Blasutig; Lamine Aoudjit; Youling Zou; Xiuwen Liu; Guo-Liang Yu; Tomoko Takano; Susan E Quaggin; Tony Pawson Journal: J Am Soc Nephrol Date: 2009-05-14 Impact factor: 10.121
Authors: Nina Jones; Ivan M Blasutig; Vera Eremina; Julie M Ruston; Friedhelm Bladt; Hongping Li; Haiming Huang; Louise Larose; Shawn S-C Li; Tomoko Takano; Susan E Quaggin; Tony Pawson Journal: Nature Date: 2006-03-08 Impact factor: 49.962
Authors: M Kestilä; U Lenkkeri; M Männikkö; J Lamerdin; P McCready; H Putaala; V Ruotsalainen; T Morita; M Nissinen; R Herva; C E Kashtan; L Peltonen; C Holmberg; A Olsen; K Tryggvason Journal: Mol Cell Date: 1998-03 Impact factor: 17.970