PTBP1 supports mouse spermatogenesis by facilitating cytoskeletal organization through the mTORC2-PKCα pathway in...

Somatic Sertoli cells in the seminiferous tubule provide structural and paracrine support for spermatogenesis. Proper regulation of Sertoli cell cytoskeleton dynamics is essential for this function; however, the regulatory mechanisms remain unclear. Here, we found that polypyrimidine tract-binding protein 1 (PTBP1) maintained cytoskeletal integrity in Sertoli cells via mTORC2 signaling. Sertoli cell-specific Ptbp1 deletion in mice resulted in germ cell loss, blood-testis barrier disruption, and male infertility. Transcriptomic analysis of purified Sertoli cells revealed the dysregulation of cytoskeletal and adhesion-related genes. RNA immunoprecipitation sequencing demonstrated that PTBP1 bound to Rictor mRNA. PTBP1 loss reduced RICTOR protein expression and downstream PKCα activation, impairing the F-actin cytoskeleton. Cytoskeletal defects caused by PTBP1 deficiency were restored by constitutively active PKCα, confirming the functional relevance of the mTORC2-PKCα axis. These findings highlighted PTBP1's role as a post-transcriptional regulator of male fertility through the maintenance of Sertoli cell architecture and spermatogenesis.