hnRNPU cooperates with SF3B3 to regulate alternative splicing and mediate Leydig cell differentiation and testosterone synthesis in mice

In this study, we identify the RNA-binding protein hnRNPU as a critical splicing regulator in mouse LCs. Conditional knockout of Hnrnpu in LCs severely disrupts male fertility, characterized by drastically reduced testosterone levels, abolished male sexual behavior, impaired testicular development, decreased sperm numbers and defective sperm morphology. Multi-omics integrative analyses revealed that the expression of many key genes (e.g., Cyp11a1, Hsd3b1, Hsd17b3) involved in testosterone synthesis was markedly dysregulated in hnRNPU-deficient LCs, and that hnRNPU could directly bind to target genes associated with the mitotic cell cycle to modulate their AS.