Expression analysis and localization of wt1, ad4bp/sf-1 and gata4 in the testis of catfish, Clarias batrachus: Impact of wt1-esiRNA silencing

• Wt1, Ad4bp/Sf-1 and gata4 were localized in spermatogonia and spermatocytes.
• Higher expression of these genes were observed in developing and adult testis.
• Transient silencing of wt1 decreased the expression of steroidogenic enzyme genes.
• Induction by hCG upregulated wt1, ad4bp/sf-1 and gata4 expression.

In teleosts, a comprehensive role or interaction of wt1, ad4bp/sf-1 and gata4 genes in relation to gonadal development and/or recrudescence was never attempted. Present study aimed to identify the involvement of these genes during testicular development of catfish, Clarias batrachus. Dominant expression of wt1 and gata4 was observed in developing and adult testis, while ad4bp/sf-1 showed steady expression. Localization of these genes in adult testis revealed their presence in spermatogonia, spermatocytes and interstitial/Leydig cells. Significant high expression during pre-spawning and spawning phases, and upregulated levels of these genes after hCG induction authenticated gonadotropic regulation. Transient silencing of wt1-esiRNA displayed decrease in wt1 expression, which further downregulated the expression of ad4bp/sf-1 and gata4, and certain steroidogenic enzyme genes related to androgen production. These results suggest that wt1 might target ad4bp/sf-1 and gata4 expression, and also have regulatory influence either indirectly or directly on the steroidogenic enzyme genes of catfish.

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