MiR-34 promotes apoptosis of lens epithelial cells in cataract rats via the TGF-β/Smads signaling pathway.

Abstract

To discuss the effect of micro ribonucleic acid (miR)-34 on the lens epithelial cell functions in the cataract rats. Differentially expressed miRNAs in the lens epithelial cells of the cataract rats were screened out by analyzing microarrays. The lens epithelial cells of the cataract rats transfected with miR-34 mimics were set as transfection group. Cells with silenced transforming growth factor-β (TGF-β) using RepSox were regarded as the transfection + inhibitor group, and the cells transfected with NC constituted control group. Relative expressions of miR-34, key genes in the TGF-β/Smads signaling pathway and apoptosis-related proteins [B-cell lymphoma-2 (Bcl-2), Bcl-2 associated X protein (Bax), Bcl-2 associated K protein (Bak), caspase-9 and surviving] in the control group, transfection group, and transfection + inhibitor group were detected. The proportions of apoptotic cells in the three groups were determined via flow cytometry. The differentially expressed miRNAs in the lens epithelial cells of the cataract rats included miR-5, miR-128, etc. Among the tested miRNAs, miR-34 presented remarkably downregulated expression [log2 fold change (FC) =-2.11, p=0.000]. After the lens epithelial cells of the cataract rats were transfected with miR-34 mimics, the expression of miR-34 was evidently elevated (p=0.000), while the expressions of TGF-β, Smad1, and Smad3 were significantly up-regulated. Following the treatment with the TGF-β inhibitor RepSox, the expressions of TGF-β, Smad1, and Smad3 were downregulated. After transfection of miR-34 mimics in lens epithelial cells of the cataract rats, upregulated Bax and Bak, downregulated Bcl-2 and surviving, and elevated apoptosis rate were observed. After the TGF-β inhibitor RepSox was added, the expressions of Bax and Bak declined prominently, while those of Bcl-2 and survivin were on the contrary, manifesting a declining cell apoptosis rate. The expression of caspase-9 had no significant change among the three groups. The proportion of apoptotic cells in control group, transfection group, and transfection + inhibitor group was 2.33%, 38.14%, and 16.88%, respectively, displaying differences among the three groups (p=0.002). MiR-34 can promote the apoptosis in lens epithelial cells of cataract rats via the TGF-β/Smads signaling pathway.