Expression and localization of EphA2 gene in testis and epididymis of Tibetan sheep

Testicular development and sperm production are regulated by several complex and precise factors. Erythropoietin-producing hepatocellular A2 (EphA2) is a transmembrane protein involved in intercellular signaling. Four healthy male Tibetan sheep aged 3 months, 1 year, and 3 years were selected to investigate the expression characteristics and biological functions of the EphA2 gene in developmental Tibetan sheep testis and epididymis. The expression and cellular distribution characteristics of the EphA2 gene in testis and epididymis at different developmental stages were detected by quantitative real-time Polymerase Chain Reaction (PCR), western blot, and immunofluorescence (IF) staining, respectively. The results of mRNA detection showed that the expression of the EphA2 gene in the testis, epididymis head, body, and tail tended to decrease with age. Results showed that with increasing age, the expression of EphA2 protein significantly increased in the testis and epididymal head (P < 0.01) while significantly decreasing in the epididymal body and tail (P < 0.01) (except for the epididymis at 3 months and 1 year). EphA2 protein was mainly localized in the gonocytes of the 3-month-old testes, spermatogonia of the 3-year-old group, and spermatocytes of the 1- and 3-year-old groups. In the epididymis, it is mainly present in the loose connective tissue of the epididymal head and body of the 3-month-old group and the pseudostratified columnar ciliated epithelial cells of the epididymal head and body of the 1- and 3-year-old groups, as well as in the entire developmental stage of the epididymal tail. In conclusion, EphA2 may play an important regulatory role in early germ cell development, sperm differentiation, and sperm maturation. This provides a clue for further understanding of the molecular mechanisms of the EphA2 gene in spermatogenesis and maturation in Tibetan and other sheep.