Cellular and molecular mechanism for reproductive capacity of male Mongolian cattle basing on single-cell sequencing for testis

Abstract Mongolian cattle is an excellent local breed with strong reproductive ability in Inner Mongolia of China. Spermatogenesis is a comprehensive process to decide the reproductive ability. In order to understand the cellular and molecular mechanism of spermatogenesis of Mongolian cattle, scRNA-seq was used to describe the heterogeneity of cells and gene expression profile in testis. The results showed 8 cell clusters. Among somatic cells, Sertoli cells were obviously more in young cattle than that in adult cattle, moreover, there were 4 subpopulations of Sertoli cells (SC1∼4). In the matured Sertoli cells (SC4), up-regulated genes were mainly enriched in immune system activity, enhancing immune response, and regulating cellular processes. The top 5 marker genes (BTG2, FOSB, EGR1, JUNB, CCNL1) were highly expressed in the testes of Mongolian cattle and water buffalo compared to Holstein cattle, which were highly expressed in the developing SC1. Gain/loss-of-function of EGR1 in Sertoli cells isolated from Mongolian cattle testes positively regulated the expression of FOS and JUN. The results indicated that SC1 acted as the foundation and SC4 as the matured supportive cells and EGR1 would promote the spermatogenesis by regulating AP-1 transcription factor member FOS and JUNto maintain strong reproductive capacity of Mongolian cattle.