hnRNPU is required for spermatogonial stem cell pool establishment in mice.

The continuous regeneration of spermatogonial stem cells (SSCs) underpins spermatogenesis and lifelong male fertility, but the developmental origins of the SSC pool remain unclear. Here, we document that hnRNPU is essential for establishing the SSC pool. In male mice, conditional loss of hnRNPU in prospermatogonia (ProSG) arrests spermatogenesis and results in sterility. hnRNPU-deficient ProSG fails to differentiate and migrate to the basement membrane to establish SSC pool in infancy. Moreover, hnRNPU deletion leads to the accumulation of ProSG and disrupts the process of T1-ProSG to T2-ProSG transition. Single-cell transcriptional analyses reveal that germ cells are in a mitotically quiescent state and lose their unique identity upon hnRNPU depletion. We further show that hnRNPU could bind to Vrk1 , Slx4 , and Dazl transcripts that have been identified to suffer aberrant alternative splicing in hnRNPU-deficient testes. These observations offer important insights into SSC pool establishment and may have translational implications for male fertility. [Display omitted] • hnRNPU expression traverses germ-cell development and is abundant in perinatal germ cells • hnRNPU regulates the establishment of the SSC pool and is essential for male fertility • Loss of hnRNPU causes ProSG-to-SG transition failure and Sertoli-cell-only syndrome in mice • hnRNPU modulates alternative splicing of cell-cycle-related genes in male germ cells Wen et al. report that loss of hnRNPU results in failure to establish a spermatogonial stem cell pool, leading to Sertoli-cell-only syndrome. Single-cell RNA sequencing revealed that ProSG-to-SG transitions are disturbed in Hnrnpu -deficient mice. hnRNPU affects the migration and differentiation of ProSG by regulating alternative splicing of cell-cycle-related genes. [ABSTRACT FROM AUTHOR]