The Poly(rC) binding protein 2 is required for spermatogenesis by regulating alternative splicing and mRNA stability

RNA-binding proteins (RBPs) govern mRNA fate and critically regulate spermatogenesis. The poly(rC)-binding protein 2 (PCBP2), a testis-enriched RBP, remains uncharacterized in spermatogenesis. In this study, we identified and validated PCBP2 downregulation in testicular tissues from patients with non-obstructive azoospermia (NOA) by integrating bulk and single-cell RNA sequencing (scRNA-seq) datasets. To investigate its function, we generated mice with a germline-specific ablation of Pcbp2. These mice exhibited delayed meiotic prophase and impaired spermiogenesis. Specifically, we observed a reduction in mid-pachytene spermatocytes and a distinct developmental arrest at step 9 of spermiogenesis. Mechanistically, integrated IP-MS, RNA-Seq, and RIP-Seq analyses revealed that PCBP2 recruits hnRNPU and DDX5 to key transcripts related to meiosis (Spo11, Tdrd5 and Brme1) and spermiogenesis (Eif4g3, Piwil1 and Dlec1), thereby orchestrating mRNA stability and alternative splicing of target genes. This study establishes PCBP2 as an indispensable multifunctional RBP required for meiotic progression and spermiogenesis. Our findings identify a novel mechanism of RBP-driven male infertility and indicate PCBP2 as a potential diagnostic marker and therapeutic target for NOA.