LncRNA ‐412.25 activates the LIF / STAT3 signaling pathway in ovarian granulosa cells of Hu sheep by sponging miR ‐346

Abstract Although long non‐coding RNAs (lncRNAs) are reported to regulate follicular development and reproductive disease pathogenesis, the underlying mechanisms have not been elucidated. In this study, lncRNA expression profiling of different‐sized healthy follicles from Hu sheep with different prolificacy revealed 50 613 lncRNAs. Numerous lncRNAs were differentially expressed among different comparison groups. This study characterized one novel transcript, lncRNA‐412.25 (from healthy follicles with a diameter of >5 mm), which was predominantly expressed in the high prolificacy group and localized to the cytoplasm of granulosa cells (GCs). LncRNA‐412.25 knockdown promoted and inhibited Hu sheep GC apoptosis and proliferation, respectively. Interestingly, lncRNA‐412.25 could directly bind to miR‐346, which can target the gene of leukemia inhibitory factor (LIF). Knockdown of lncRNA‐412.25 promoted GC apoptosis by downregulating LIF expression, where this effect was attenuated by miR‐346. Moreover, the miR‐346 inhibitor mitigated the lncRNA‐412.25 knockdown‐induced downregulation of phosphorylated protein of signal transducer and activator of transcription 3 (STAT3), which was validated using immunofluorescence analysis. Our results demonstrated that lncRNA‐412.25 regulates GC proliferation and apoptosis in Hu sheep by binding to miR‐346 and then activating the LIF/STAT3 pathway. These findings provide novel insights into the mechanisms underlying prolificacy in sheep.