The regulatory role of INSIG1 in testicular Sertoli cells in boars.

The fertility of boars is affected by testicular development and spermatogenesis, Sertoli cells (SCs) play a central role in these processes and are regulated by multiple genes and factors. Insulin-induced gene 1 (INSIG1) is a transmembrane protein involved in various physiological processes, such as cell proliferation, differentiation, and cholesterol metabolism. However, the role of INSIG1 in SCs and development of porcine testes has not been reported. In this study, we reported that the expression level of INSIG1 gradually increased in testicular tissues at 2, 80, and 240 days. In vitro, transfection of SCs with the overexpression plasmid pBI-INSIG1 and interference fragment siRNA indicated that INSIG1 could cause cell cycle arrest and inhibit cholesterol production and cell proliferation. Western blotting and immunofluorescence staining revealed that INSIG1 deactivated the Wnt/β-catenin signaling pathway by downregulating the expression of WNT1 and reducing the translocation of β-catenin to the nucleus. Activation of the Wnt/β-catenin signaling pathway mitigates INSIG1-mediated effects, including the inhibition of SCs proliferation and the upregulation of androgen receptor (AR) levels. Our results indicated that INSIG1 plays a significant role in the proliferation and maturation of porcine SCs, revealing emerging directions to investigate in both reproductive biology and agricultural sciences.