The regulatory role of BMP4 in testicular Sertoli cells of Tibetan sheep.

The fertility of male Tibetan sheep is mainly affected by testicular development and spermatogenesis. In these processes, Sertoli cells (SCs) play a central role and are regulated by a variety of genes and factors. BMP4 is mainly distributed in Sertoli cells, and its expression level increases with age. Overexpression of the BMP4 gene in Tibetan sheep testis SCs revealed elevated expression of BMP4 protein and its downstream genes SMAD5, pathway receptor proteins BMPR1A and BMPR1B; followed by elevated expression levels of cell proliferation-related genes and decreased expression levels of apoptosis-related genes. Meanwhile, the expression of tight junction proteins was also elevated. These results indicate that BMP4 affects testicular development by regulating the Sertoli cells and blood­testis barrier, thereby affecting the spermatogenesis of Tibetan sheep.