Characterization of the Es-DDX52 involved in the spermatogonial mitosis and spermatid differentiation in Chinese mitten crab (Eriocheir sinensis)

Spermatogenesis involves a series of process including exiting from the mitotic cell cycle, entry into meiosis, completion of complex differentiation programs, and producing spermatozoa. Expression of various genes in an ordered manner, and interactions between various genes and their protein products, primarily controlled at the post-transcriptional level with DEAD-box RNA helicases playing a crucial role in germ cell development, are required for production of fertile sperm. Many members of this family have been deeply studied in spermatogenesis, such as DDX3X, DDX25 and DDX4, but few data are available on DDX52. In this study, we analyzed the expression patterns of Es-DDX52, Es-DDX6, Es-Vasa and Es-XRN1 both at mRNA and protein levels in different tissues and during gonadal development. It showed that Es-vasa, Es-DDX6 and Es-Xrn1, components of cytoplasmic foci P-bodies, have the similar transcriptional expression pattern, while Es-DDX52 has the reverse tendency. Furthermore, Es-DDX6 and Es-XRN1 proteins have the same localization in testicular tissues. Es-DDX52 mainly distributed in the cytoplasm of spermatogonia, only localized in the nucleus of early and middle spermatid and shifted to pre-acrosome vesicle (later developed into apical cap and acrosome tube) at both mRNA and protein levels. These results indicated that Es-DDX52 may participate in regulation of P-bodies and microtubules by Es-XRN1, and involved in the mitosis of spermatonia and spermatid differentiation.