CTRP3 Mediates Cholesterol Transport in Renal Tubular Cells under High Glucose Condition by Regulating Sirt1
LIANG Zihui1, ZHU Yan2, REN Yunzhuo3, WU Ming3, HAN Weixia3, ZHANG Guoyu3, HU Yue3, DU Chunyang3*
The purpose of this study is to investigate the role and molecular mechanisms of CTRP3 on cholesterol transport in renal tubular cells under high glucose condition. Cultured HK-2 cells were randomly divided into normal glucose group (NG), NG plus CTRP3 group (NG+CT), high glucose (HG), HG plus CTRP3 group (HG+CT), HG plus CTRP3 treatment plus siRNA transfection group (HG+CT+siRNA), HG plus CTRP3 treatment plus Sirt1 siRNA transfection group (HG+CT+siSirt1). Cholesterol content and efflux levels in different groups were detected using cholesterol detection kits according to instructions of the manufacturer, and cholesterol accumulation was detected by Filipin staining. The activity of Sirt1 enzyme was measured using commercial detection kit. Western blot was used to detect the protein expression of CTRP3, Sirt1, LXRα, and ABCA1 in HK-2 cells. The level of CTRP3 mRNA was detected by Real-time PCR. Recombinant protein CTRP3 treatment significantly inhibited the HG-induced cholesterol accumulation and promoted the level of cholesterol efflux in HK-2 cells. In addition, down -regulation of CTRP3, Sirt1, LXRα, and ABCA1protein expression and Sirt1 activity induced by HG were markedly prevented by treatment with recombinant protein CTRP3. After the application of Sirt1 siRNA to inhibit the expression of Sirt1,the above regulatory effects of CTRP3 on HK-2 cells disappeared. These findings indicated that CTRP3 had protective effects on HG-induced cholesterol accumulation in HK-2 cells. The mechanism of role performed by CTRP3 may include, at least in part regulating the expression of Sirt1 and promoting the cholesterol efflux.
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