MicroRNA-34b-5p targets PPP1R11 to inhibit proliferation and promote apoptosis in cattleyak Sertoli cells by regulating specific signaling pathways.

Cattleyaks, a hybrid of (♂) and yak (♀), exhibit the marked productivity and adaptability of plateau, but suffer from male infertility. Small non-coding RNAs, especially miRNAs, play crucial roles in spermatogenesis and affect the growth of Sertoli cells (SCs). The objective of the present study was to explore the interaction between miR-34b-5p and protein phosphatase 1 regulatory inhibitor subunit 11 (PPP1R11) and its effect on cattleyak SCs. RT-qPCR was used to determine the expression pattern of miR-34b-5p and PPP1R11, while the cellular and subcellular localization of PPP1R11 was determined by immunohistochemistry and immunocytochemistry. The interaction between MiR-34b-5p and PPP1R11 was evaluated by immunofluorescence, proliferation, apoptosis, and western blotting assays. The potential binding sites between miR-34b-5p and PPP1R11 were uncovered through targeted search of an online database, and verified using a dual luciferase reporter system. Our data show that miR-34b-5p is differentially expressed in the testes and SCs of cattleyaks compared to yaks. Overexpression of miR-34b-5p in SCs suppressed proliferation and induced apoptosis, while the effects of miR-34b-5p knockdown were the reverse. The 3'UTR of PPP1R11 was identified as a potential target site of miR-34b-5p, and this was validated by online database searches and our data from the dual-luciferase reporter assay, and it displayed an inverse expression pattern to miR-34b-5p in SCs. The effects of silencing PPP1R11 by siRNA were similar to the results of miR-34b-5p upregulation, but significantly different from miR-34b-5p downregulation in cattleyak SCs. The effects with PPP1R11 overexpression were opposite, suggesting a novel biofunctional role of PPP1R11 inactivation in depressing cattleyak SCs growth. Lastly, we confirmed that miR-34b-5p inhibited PPP1R11 expression and induced apoptosis by regulating proliferation- and apoptosis-related genes in SCs. Thus, miR-34b-5p regulates the apoptosis and proliferation of cattleyak SCs via targeting PPP1R11, which can provide an innovative direction for exploring the mechanism of cattleyak male sterility.