Sirt3 regulated apoptosis and aerobic glycolysis during renal interstitial fibrosis

Objective  To observe the expression of silent information regulator 3 （Sirt3）, detect the level of aerobic glycolysis in renal fibrosis model and explore the role of Sirt3 in renal interstitial fibrosis.

Methods  Wild-type and Sirt3 gene knockout mice were utilized for constructing a renal fibrosis model by unilateral ureteral obstruction （UUO） and contralateral kidneys were used as sham surgery control group. The pathological changes of kidney were observed after hematoxylin-eosin （HE） and Masson stain. The expressions of Sirt3, signature proteins associated with fibrosis （fibronectin & collagen-I）, key enzymes of aerobic glycolysis hexokinase-II （HXK-II） & pyruvate kinase M2 （PKM2） and caspase-3 were evaluated by Western blot. Apoptotic level of renal tubular epithelial cells （RTECs） was assessed by terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling （TUNEL） stain. Human renal tubular epithelial cells （HK-2） were divided into control and si-Sirt3 groups and exposed to transforming growth factor-β1 （TGF-β1）. Western blot was utilized for detecting the expressions of fibronectin, collagen-I, HXK-II and PKM2. Flow cytometry was employed for detecting apoptosis.

Results  Apoptosis and aerobic glycolysis accelerated significantly during in vivo and in vitro fibrotic reactions. Sirt3 became markedly down-regulated. Sirt3 gene knockout further aggravated renal tubular epithelial cell apoptosis and abnormal aerobic glycolysis and promoted renal interstitial fibrosis.

Conclusions  Sirt3 may alleviate renal interstitial fibrosis through suppressing aerobic glycolysis of RTECs. It plays some protective role in chronic kidney disease （CKD）.