Es-SOX8 regulates the morphological changes of the sperm nucleus of Eriocheir sinensis by activating Es-BMP2 transcription

The SRY-related high mobility group(HMG)box(SOX)transcription factors participate in many physiological processes of animal growth,development,and reproduction and are related to spermatogenesis in many species.However,the relationship between SOX and spermatogenesis in Eriocheir sinensis is rarely reported.Here,we studied the role of Es-SOX8 in the spermatogenesis of E.sinensis and its possible regulation mechanism.Immunofluorescence results demonstrated Es-SOX8 signal in both cytoplasm and nucleus of spermatogonia,spermatocytes as well as spermatids,but not in mature spermatozoa.Hematoxylin and eosin staining showed a significant increase in the number of spermatozoa with abnormal nuclear morphology in vivo,described as prominent edges and corners,after the knockdown of Es-SOX8 through RNA interference.This indicated a possible role of Es-SOX8 in the nuclear deformation process in the spermatogenesis of E.sinensis.Analysis of the mRNA levels of Es-bone morphogenetic protein 2(BMP2)in the Es-Sox8 knocked-down testis tissue revealed significantly decreased transcription of Es-BMP2.Chromatin immunoprecipitation results showed the binding of Es-SOX8 protein to the promoter region of Es-BMP2.Thus,Es-SOX8 can directly regulate the transcription of Es-BMP2 by activating the promoter of Es-BMP2 and thus affects the sperm nucleus deformation of E.sinensis.