Molecular cloning, characterization, and function analysis of the AMH gene in Yak (Bos grunniens) Sertoli cells

Sertoli cells (SCs) are important testicular somatic cells that carry out various functions in spermatogenesis. Understanding the biological mechanisms underlying SC development may facilitate the understanding of animal reproduction. Anti-Mullerian hormone (AMH) is a dimeric glycoprotein produced by SCs and plays essential roles in spermatogenesis. In this study, we cloned the coding sequence of the yak AMH, predicated the structure of AMH protein, analyzed AMH expression in the testis at different stages, and studied the functions of AMH in yak SCs. The open reading frame (ORF) of the yak AMH contained 1728 bp and encoded 575 amino acids. Structural analysis revealed that the yak AMH protein had a highly conserved transforming growth factor-β (TGF-β) domain. The mRNA expression level for the AMH gene in yak testis increased significantly from the fetal stage to calf stage, then decreased with the increase of age. The highest expression was found in calf stage. Cell proliferation was depressed in AMH-deficient SCs. Expression of several genes involved in SC proliferation and development, including PCNA, BCL-2, BAX, CASP3, AR and AMHR2 were altered after knockdown of AMH. Also, three SC-secreted factors essential for spermatogenesis, SCF, GDNF and ABP, were repressed at the transcription level after AMH knockdown in yak SCs. Moreover, supplementation with exogenous AMH protein partially rescued SC proliferation, and the expression of PCNA, BCL-2, AR and AMHR2 after AMH gene interference. This research provided theoretical basis for understanding the mechanism by which AMH regulates yak spermatogenesis and might give new insights in improving yak reproductive performance in the future.