Tengteng Xu

Follicular atresia constitutes a major constraint on sow reproductive performance. Aberrant miRNA expression is well documented to promote follicular atresia. However, precise identification of the functional miRNAs responsible for this process remains a formidable challenge. In this study, we integrated multiple transcriptome datasets and identified miR-149, a miRNA located within the quantitative trait loci (QTL) associated with litter size in sow. Notably, miR-149 was highly expressed in atretic follicles and ovaries of sow with low litter size. Subsequent in vitro culture of ovarian granulosa cells (GCs) combined with miR-149 overexpression assays revealed that miR-149 significantly promotes the expression of cleaved caspase 3 (c-caspase 3), a marker of apoptosis in ovarian GCs. Mechanistic studies revealed that miR-149 functions as small activating RNA (saRNA) to activate the transcription of Caspase 8. This triggers the death receptor-mediated apoptotic, upregulates the expression of Caspase 3, and ultimately accelerates apoptosis in ovarian GCs. Collectively, these results indicate that miR-149 acts as negative regulator of sow reproduction. This study elucidates the miR-149/Caspase 8/Caspase 3 signaling axis as a novel pathway governing sow fertility, which provides molecular targets for improving reproductive performance in sow.

The corpus luteum number in sows is a key reproductive indicator for measuring ovulation rate and reproductive efficiency. Its formation is precisely regulated by a complex gene regulatory network composed of multi-level molecular interactions. To systematically elucidate the molecular basis of this trait, this study comprehensively analyzed genes located within QTL for corpus luteum number. This approach identified a series of key regulatory molecules specifically expressed in the ovary, including transcription factors (TFs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs). Using bioinformatics methods to predict the target genes of candidate miRNAs, combined with functional enrichment analysis, revealed that these target genes were significantly enriched in multiple core reproductive pathways closely related to cell proliferation, differentiation, and hormone regulation, including the ErbB signaling pathway, PI3K-Akt signaling pathway, and TGF-beta signaling pathway. Based on the above findings, this study ultimately constructed a TF-lncRNA-miRNA-mRNA network, which is associated with QTL for corpus luteum number. Furthermore, key genes were validated via quantitative real-time PCR (qRT-PCR). Significant positive correlations were identified between the transcription factor NEUROG2 and lncRNA LOC102167554, along with its potential target gene ESRP1, as well as between transcription factor SNAI2 and lncRNAs (LOC102167554, LOC102167796) and their potential target genes (FXR, ERBB4). In addition, the functional validation results showed that the interference of LOC102167554 significantly reduced the proliferation ability of sGCs. These key genes represent potential targets for genetic improvement of sow reproduction.