Angiotensin II Receptor Blocker Induced Inhibition of Cellular Hypertrophy and Differential Expression of Cyclin-dependent Kinase Inhibitors in Cultured Podocytes Stimulated by Long-term High Glucose / 대한신장학회잡지

ABSTRACT

BACKGROUND: Hypertrophy of podocytes is observed in type 2 diabetic patients. Cellular hypertrophy requires combined effects of various mitogen- induced entry into the cell cycle and subsequent cell cycle arrest at the G1/S interphase. This cell cycle arrest is mediated by various cyclin-dependent kinase inhibitors (CKIs). We investigated the effect of angiotensin II receptor blocker (ARB) treatment on podocyte hypertrophy and CKIs expression in cultured podocytes stimulated by long-term high glucose. METHODS: Immortalized mouse podocytes were cultured in media containing 5.6 mM normal glucose (NG), 30 mM high glucose (HG), or NG+angiotensin II (AII, 10(-7)M) for 7 days with or without ARB (L-158,809, 10(-6)M). Cellular hypertrophy was assessed by measurement of cellular protein/cell counts, and CKIs mRNA and protein expression were assessed by reverse-transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. RESULTS: Cellular hypertrophy was induced in podocytes exposed to HG or AII compared to NG cells and this HG-induced cellular hypertrophy was inhibited with ARB treatment by 70% (p<0.05). In addition, there were 1.5-fold and 2.0 fold increases in p27Kip1 mRNA and protein expression, respectively, in HG-stimulated podocytes compared to NG- treated cells (p<0.05). p27Kip1 mRNA and protein expression were also increased in cultured podocytes stimulated by AII by 156% and 199%, respectively (p<0.05). ARB treatment ameliorated HG-induced increase in p27Kip1 mRNA by 75% and protein expression by 70% (p<0.05). In contrast, there were no significant changes in p21Cip1 and p57Kip2 protein expression in cultured podocytes exposed to HG or AII. CONCLUSION: High glucose induced significant cellular hypertrophy and increased p27Kip1 mRNA and protein expression in cultured mouse podocytes, and these changes were effectively inhibited by ARB treatment.