The fusion gene hsf5-rnf43 in Nile tilapia: A potential regulator in the maintenance of testis function and sexual differentiation

We identified that the genes heat shock transcription factor 5 (hsf5) and ring finger protein 43 (rnf43) happened fusion in Nile tilapia (Oreochromis niloticus), called hsf5-rnf43, and provided the characteristic and functional analysis of hsf5-rnf43 gene in fish for the first time. Analysis of spatiotemporal expression showed that hsf5-rnf43 was specifically expressed in the testis and located in primary spermatocytes of adult Nile tilapia and gradually increased during testis development from 5 to 180 days after hatching. We also found DNA methylation regulated sex-biased expression of hsf5-rnf43 in the early development of Nile tilapia, and was affected by high temperature during the thermosensitive period of Nile tilapia sex differentiation. Therefore, we first reported that the fusion gene hsf5-rnf43 was sex-biased expressed in the testis regulated by DNA methylation and affected by high temperature, which may be involved in the maintenance of testis function and sex differentiation of Nile tilapia. [Display omitted] •The genes hsf5 and rnf43 fused to form hsf5-rnf43 in Nile tilapia•Hsf5-rnf43 was located in primary spermatocytes and increased as testis developed•DNA methylation controlled hsf5-rnf43 expression as testis developed•Temperature affected DNA methylation regulating hsf5-rnf43 sex-biased expression Ichthyology; Genetics; Epigenetics; Developmental biology