miR-34c inhibits proliferation and enhances apoptosis in immature porcine Sertoli cells by targeting the SMAD7 gene

MicroRNAs(miRNAs) are implicated in swine spermatogenesis via their regulations of cell proliferation, apoptosis, and differentiation. Recent studies indicated that miR-34 c is indispensable in the late steps of spermatogenesis. However, whether miR-34 c plays similar important roles in immature porcine Sertoli cells remain unknown. In the present study, we conducted two experiments using a completely randomised design to study the function roles of miR-34 c. The results from experiment I demonstrated that the relative expression level of miR-34 c in swine testicular tissues increased(P=0.0017) quadratically with increasing age, while the relative expression level of SMAD family member 7(SMAD7) decreased(P=0.0009) with curve. Furthermore, miR-34 c expression levels showed a significant negative correlation(P=0.013) with SMAD7 gene expression levels. The results from experiment II indicated that miR-34 c directly targets the SMAD7 gene using a luciferase reporter assay, and suppresses(P<0.05) SMAD7 mRNA and protein expressions in immature porcine Sertoli cells. Overexpression of miR-34 c inhibited(P<0.05) proliferation and enhanced(P<0.05) apoptosis in the immature porcine Sertoli cells, which was supported by the results from the Cell Counting Kit-8(CCK-8) assay, the 5-Ethynyl-2′-deoxyuridine(EdU) assay, and the Annexin V-FITC/PI staining assay. Furthermore, knockdown of SMAD7 via small interfering RNA(siR NA) gave a similar result. It is concluded that miR-34 c inhibits proliferation and enhances apoptosis in immature porcine Sertoli cells by targeting the SMAD7 gene.