<i>Ybx1</i> deficiency impairs spermatid development and male fertility without affecting meiosis in mice: insights into spermatogenesis

Spermatogenesis is a complex process that is required for sperm production. Multiple RNA-binding proteins participate in regulating spermatogenesis. Y-box-binding protein 1 (YBX1) is involved in transcriptional regulation, mRNA stabilization, and translational repression. However, its specific role in spermatogenesis remains unclear. This study investigated the role of YBX1 in spermatogenesis using a Ybx1 conditional knockout (Ybx1 cKO) mouse model. By analyzing the phenotype of Ybx1 cKO mice, we investigated the role of YBX1 in spermatogenesis and male fertility. The morphology and weight of Ybx1 cKO mouse testes were similar to those of wild-type (WT) testes. Sperm count and motility were lower in Ybx1 cKO mice than in WT mice. Histological analysis showed reduced numbers of elongated spermatids in seminiferous tubules and spermatozoa in tubules of the epididymis in Ybx1 cKO mice. Although YBX1 was highly expressed in the cytoplasm of spermatocytes, meiosis progressed normally in Ybx1 cKO spermatocytes. Finally, the fertilization potential of spermatozoa from Ybx1 cKO epididymis was decreased. In conclusion, our results indicate that YBX1 participates in the regulation of spermatid development but is dispensable for meiosis.