SOX8 is essential for male sexual differentiation in the Chinese soft-shelled turtle Pelodiscus sinensis

Abstract

SOX8, which belongs to SOXE transcription factor subfamily together with SOX9, participates in sex differentiation and testicular development by enhancing the function of SOX9 in mammals. However, the functional role of SOX8 in sex differentiation has not yet been identified in any non-mammalian vertebrates. Here, we found in the Chinese soft-shelled turtle Pelodiscus sinensis that SOX8 exhibited male-specific higher expression from stage 14 to 18, the critical period of sex determination, prior to the onset of gonadal differentiation. In addition, SOX8 was rapidly down-regulated during male-to-female sex reversal induced by estradiol. Moreover, knockdown of SOX8 led to complete feminization of ZZ P. sinensis, determined by gonadal morphology and distribution of germ cells, as well as the down-regulation of testicular marker DMRT1 and the up-regulation of ovarian regulator FOXL2. In conclusion, this study provides evidence that SOX8 is a key regulator of early male differentiation in P. sinensis, highlighting the significance of the SOX family in reptile sex determination.

Cross-species genomic survey reveals a single origin of the soft-shelled turtles

“…We also found the similar patterns in other star genes for sex determination in P . sinensis , such as Amh (Zhou et al, 2019), Foxl2 (Jin et al, 2022), Rspo1 (Zhang et al, 2021), Esr1 (Li et al, 2022b), and Sox8 (Yang et al, 2023). Accordingly, we hypothesize that the W chromosome may contain different SDGs and regulates sex determination in P .…”

Reproduction-associated pathways in females of gibel carp (Carassius gibelio) shed light on the molecular mechanisms of the coexistence of asexual and sexual reproduction

“…These genes were shown to promote male differentiation and repress female-specific differentiation of the gonads, and they are also involved in brain sexual differentiation [ 114 – 118 ] as well as in XY reversal in sex-alternating fish species [ 115 ]. Gynogenetic females of C. gibelio also upregulated ncoa2 , a transcriptional coactivator of steroid receptors and nuclear receptor, as well as sox8 , involved in female sex determination [ 119 ], meiotic progression, and embryonic development [ 120 ], and inhibin alpha ( inha) , involved in steroid hormone biosynthesis. Ovarian aromatase or estrogen synthetase ( cyp19a1a ), a member of the cytochrome P450 subfamily involved in steroidogenesis [ 121 ] and female folliculogenesis and gonadal differentiation, was also upregulated in gynogenetic females of C. gibelio , as was oxtr , a gene encoding the oxytocin receptor, a component of the oxytocin signalling system that modulates reproductive behaviour.…”