DDX19B modulates post-meiotic 3′-UTR profile shifts in mice

In mammals, the transition from meiotic spermatocytes to post-meiotic spermatids requires post-transcriptional reprogramming, but how nuclear mRNA-export machinery adapts remains unclear. Here we identify DDX19B, a testis-enriched DDX19/DBP5-family helicase, as a nuclear-pore-associated regulator of the post-meiotic transcriptome. DDX19B is preferentially expressed in male germ cells across this transition. Ddx19b loss does not cause overt testicular failure or infertility, yet mutant round spermatids show altered 3′ UTR profiles, with greater long-isoform representation among transcripts that normally shift toward shorter isoforms. Mechanistically, DDX19B associates with nuclear-pore-proximal proteins rather than core cleavage-and-polyadenylation complexes. It preferentially associates with long transcripts, whereas DDX19B-associated RNAs show little overlap with the major transcript cohort undergoing developmental 3′ UTR-profile shifts. More broadly, Ddx19b loss perturbs RNA-regulatory networks, including cleavage-and-polyadenylation-associated factors, supporting an indirect model of DDX19B-dependent 3′ UTR regulation. Cross-species single-cell analyses further show that the shift toward proximal 3′ UTR usage during this transition is shared across mouse, macaque and human. Together, these findings link DDX19B to RNA handling at nuclear pores and reveal conserved post-meiotic shifts in 3′ UTR profiles.