The mechanism of INO80D involved in chromatin remodeling regulating spermatogenesis in Chinese mitten crab (Eriocheir sinensis).

The INO80D protein, a component of the INO80 chromatin remodeling complex, plays a pivotal role in chromatin remodeling, gene expression, and DNA repair within mammalian sperm. In contrast to the condensed nuclear structure of mammalian sperm, Chinese mitten crab, Eriocheir sinensis, exhibits a distinctively decondensed sperm nucleus. The distribution and function of INO80D during the E. sinensis spermatogenesis were previously enigmatic. Our research endeavored to elucidate the distribution and function of INO80D, thereby enhancing our comprehension of sperm decondensation and the process of spermatogenesis in this species. Employing transcriptome sequencing, RT-qPCR, western blot analysis, and immunofluorescence techniques, we observed a pronounced upregulation of INO80D in the adult E. sinensis in comparison to the juvenile. The protein predominantly resides in the cellular nucleus, with high levels in spermatogonia and spermatocytes, less in stage I and III spermatids, and lowest in mature sperm. The results indicated that INO80D is initially instrumental in chromatin decondensation to facilitate gene accessibility and DNA repair during the early phases of spermatogenesis. Its role subsequently shifts to maintaining decondensed chromatin stability and genetic integrity during spermiogenesis. The sustained presence of INO80D during spermiogenesis is essential for the ultimate maturation of the decondensed sperm nucleus, imperative for preserving the unique decondensed state and the protection of genetic material in E. sinensis. Our study concludes that INO80D exerts a multifaceted influence on the spermatogenesis of E. sinensis, impacting chromatin decondensation, genetic integrity, and the regulation of early gene expression. This understanding could potentially improve crab breeding in aquaculture.