Abstract: Objective To study the effects and the regulation mechanism of microRNA-21 (miRNA-21, miR-21) on the expressions of matrix metalloproteinase 2 (MMP-2) and MMP-9 in podocytes under lipid polysaccharide (LPS) stimulation in phosphatase and tensin homology deleted on chromosome ten (PTEN) / phosphorylated protein kinase B (pAKT) signaling pathway. Methods The podocytes of 3-8 generation were divided into LPS group and control group. LPS group was given 10 mg/L LPS. The control group was given the same dose of phosphate buffer saline. After 24 h, expressions of miR-21, MMP-2 and MMP-9 were detected by real-time fluorescent quantitative PCR and ELISA, and the correlation between miR-21, MMP-2 and MMP-9 was analyzed. The model of podocyte injury interfered by exogenous miR-21 under LPS stimulation was constructed. The effects of exogenous miR-21 on expressions of MMP-2, MMP-9, PTEN and p-AKT were detected by Western blot assay. Results Compared with the control group, the expressions of miR-21, MMP-2 and MMP-9 increased in podocytes under LPS stimulation, and they were positively correlated (P＜0.05). After the expression of exogenous miR-21 was up-regulated, the expressions of MMP-2, MMP-9 and p-AKT increased but the expression of PTEN decreased (P＜0.05). While the expression of exogenous miR-21 was controlled, the expressions of MMP-2, MMP-9 and pAKT decreased but the expression of PTEN increased (P＜0.05). Conclusion The miR-21 can regulate PTEN / AKT pathway to affect the expressions of MMP-2 and MMP-9 under LPS stimulation in podocytes.

Key words: microRNAs, matrix metalloproteinase 2, matrix metalloproteinase 9, PTEN phosphohydrolase, oncogene protein v-akt, podocytes, microRNA-21