Role of Sirt3 in lipopolysaccharide-induced abnormal mitochondrial dynamics in renal tubular epithelial cells / 中华肾脏病杂志

ABSTRACT

Objective:To observe the expression of sirtuin 3 (Sirt3) and mitochondrial damage-associated proteins in lipopolysaccharide (LPS)-induced acute kidney injury mouse model and renal tubular epithelial cells, and to explore the role of Sirt3 in LPS-induced abnormal mitochondrial dynamics in renal tubular epithelial cells.Methods:Eighteen specific pathogen free (SPF) male C57BL/6 mice were randomly assigned to control group, LPS 24 h group and LPS 48 h group. The control group was intraperitoneally injected with physiological saline (0.1 ml/10 g), and LPS 24 h group and LPS 48 h group were intraperitoneally injected with LPS (10 mg/kg) solution. Renal functional indexes of mice were analyzed by automatic biochemical analyzer. The pathological change of the kidney was observed by HE staining, and the expressions of dynamin-related protein-1 (Drp1), optic atrophy type 1 (Opa1) and Sirt3 were evaluated by Western blotting. Expression and distribution of Sirt3 in kidney was assessed by immunohistochemistry. Human renal tubular epithelial cells (HK-2) were exposed to 10 μg/ml LPS for 24 h, and the expression of Drp1, Opa1 and Sirt3 were detected by Western blotting. Cell apoptosis was assessed by Hoechst-33342 staining. After transfection to HK-2 cells with pcDNA3.1-Sirt3 recombinant plasmid, the expressions of Sirt3, Drp1, Opa1 and cell apoptosis were detected by the same methods as above.Results:(1) The levels of blood urea nitrogen and serum creatinine in LPS group were significantly higher than those in control group (both P<0.05), and the pathological changes of kidney were obvious. (2) Compared with the control group, the expression of mitochondrial fission-associated protein Drp1 in renal tissue of LPS group was significantly higher ( P<0.05), and the expression of mitochondrial fusion associated protein Opa1 was significantly lower ( P<0.05). (3) Compared with the control group, the expression of Sirt3 in LPS group was significantly lower ( P<0.05), and immunohistochemistry results showed that Sirt3 was mainly expressed in glomerular vascular endothelial cells and renal tubular epithelial cells. (4) In vitro, LPS stimulation induced increased Drp1 expression in HK-2 cells ( P<0.05), decreased Opa1 and Sirt3 expression (both P<0.05), and increased apoptosis ( P<0.05). (5) LPS-induced mitochondrial dynamics disturbance and apoptosis were alleviated by pcDNA3.1-Sirt3 recombinant plasmid transfection. Conclusions:LPS can induce down-regulation of Sirt3 expression and disturbance of mitochondrial dynamics, and Sirt3 may play a protective role in LPS-induced acute kidney injury by regulating mitochondrial dynamics.