Role of AURKA in the hypothalamus-pituitary-testicular axis in Tibetan sheep from Tianzhu.

The mitosis-associated protein aurora kinase A (AURKA) regulates the maturation of germ cells. We have previously reported using transcriptome analysis that AURKA is expressed in yak testes. Although Tibetan sheep possess an immense economic value, their reproductive rate is low. Herein, the expression and functions of AURKA in the hypothalamus-pituitary-testicular (HPT) axis in Tibetan sheep from Tianzhu were investigated. The cDNA sequence of sheep AURKA was cloned and bioinformatics techniques were used to predict its structure. Tissue expression of AURKA was determined by qPCR, immunoblotting, immunostaining, and immunohistochemistry. The AURKA coding sequence was found to be 1218 bp in length, encoding a 405-amino acid polypeptide chain. Furthermore, the highest sequence similarity of AURKA with the corresponding sequence in other species was seen in goat and cattle; the least degree of similarity was seen in the domestic cat. In addition, AURKA expression was elevated in the testes compared to that in the hypothalamus and pituitary (p < 0.01). Moreover, AURKA was mainly localized in the hypothalamic paraventricular nucleus (magnocellular), chromophobe cells of the pituitary, and spermatogenic cells of the testis. These results indicated that AURKA might participate in sheep reproductive regulation, thus providing a reference for the study of AURKA function in the reproductive process of Tibetan sheep from Tianzhu.