Yap1 mediates miR-143 regulation of ovarian estrogen synthesis in Larimichthys crocea‌

Only the guide strand of a miRNA precursor is conventionally thought to be active, with the passenger strand degraded; however, emerging evidence shows that both the 3p and 5p strands of some precursors can be retained and remain biologically active. This study used gonadal development in the large yellow croaker (Larimichthys crocea) as a model to investigate the function of such dual-strand miRNAs. Analysis of gonadal transcriptome data identified miR-143 as a sex-biased miRNA and yap1 as its target gene. Combined in vitro and in vivo functional assays showed that both miR-143-3p and miR-143-5p repress yap1 expression at the transcriptional and translational levels, with miR-143-3p exerting a stronger repressive effect than miR-143-5p. RNA fluorescence in situ hybridization (RNA-FISH) revealed markedly different subcellular localization patterns of the two miRNA strands in gonadal tissues. Gonadal injection of miR-143-3p and miR-143-5p agomir and antagomir led to different degrees of yap1 up- and down-regulation, indicating that the two strands differ in their regulation of the target gene. Intraperitoneal injection of verteporfin down-regulated cyp19a1a mRNA expression. Together, these results indicate that miR-143 targets and regulates yap1, thereby affecting cyp19a1a expression and participating in the regulation of gonadal estrogen synthesis. This study not only reveals a novel gonadal regulatory mechanism in teleost fish, but also provides new insights into the functional significance of asymmetric miRNA strand selection and utilization, deepening our understanding of the complexity of post-transcriptional regulation.