A novel positive feedback regulatory loop, TGF-β1/SMAD4/miR-184, controls the follicular development in sows.

transcription by binding to its promoter and forming an RNA-induced transcriptional activation complex with AGO2, CTR9, DHX9, and RNA polymerase II. Consequently, a novel positive feedback loop (TGF-β1/SMAD4/miR-184) was identified. In vitro GC and follicle culture systems validated the anti-apoptotic/atretic functions of this loop. Moreover, comparative analyses showed that the levels of TGF-β1 and miR-184 in the follicles of high-fertility sows were significantly higher than those in low-fertility sows. Our findings highlight the critical role of the interaction between TGF-β1 and miR-184 in inhibiting GC apoptosis and follicular atresia, providing potential targets for improving follicular development and sow fertility.