Ftz-f1 is involved in gonadal development by transcriptionally regulating the cyp19a1 gene in Chinese tongue sole (Cynoglossus semilaevis).

The cyp19a1 gene is a ubiquitous sex-related gene that encodes aromatase, which catalyzes the conversion of androgen to estrogen. Expression of the cyp19a1 gene is closely tied to female sex differentiation. Therefore, we studied sexual expression differences and the transcriptional regulatory mechanism in a fish that is easily sex-reversible, the Chinese tongue sole (Cynoglossus semilaevis). The results showed that cyp19a1 was expressed in the gonads of males, pseudomales, and females, specifically in the seminiferous lobule cavity and sertoli cells of the testis, as well as within oocytes of the ovary. The results of dual-luciferase reporter assay in HEK293T cells and overexpression ftz-f1 experiment in in vitro-cultured Chinese tongue sole ovarian cells revealed that the Ftz-f1 transcription factor regulated the cyp19a1 gene. Furthermore, we concluded that the CTGGCCTTCCT sequence located at -952 position was the transcriptional binding sequence according to fragment deletion and directed base mutation of dual-luciferase reporter assay. In summary, Ftz-f1 transcriptionally regulated the sex-related cyp19a1 gene by binding to the -952 site to affect gonadal development. These results will enhance the precision of female-biased breeding for Chinese tongue sole at the molecular level, providing valuable insights for the aquaculture industry.