Abstract: 【Objective】 This study was aimed to clone and obtain the keratin 79 (KRT79) gene from the skin in Hetian sheep,investigate the effects of androgens on the skin structure of Hetian sheep,and understand the role of KRT79 in the process of influencing the skin structure of Hetian sheep through androgens,so as to lay the foundation for in-depth research on the function of KRT79 in sheep skin and the mechanism of androgen on the expression and regulation of KRT79 gene. 【Method】 Fifteen 2-year-old Hetian ewes were randomly divided into five groups with three in each group.Corn oil was injected into Hetian sheep in control group by intramuscular injection,while testosterone at doses of 1,2,3,and 4 mg/kg BW were injected into Hetian sheep in four experimental groups every three days for a total of 42 days.On the 42nd day,the back skin tissue was collected.Total RNA was extracted from the skin of Hetian sheep in control group,and the KRT79 gene CDS sequence was amplified by PCR,cloned and sequenced.The obtained KRT79 gene sequence of Hetian sheep was compared with the corresponding gene sequences of Ovis aries and other species using DNAStar software,and the phylogenetic tree of KRT79 gene of each species was constructed by Mega 5.0 software.The physicochemical property and structural characteristic of KRT79 protein were analyzed by bioinformatics online website.HE staining was used to observe the changes in the skin structure of Hetian sheep treated with testosterone.Real-time quantitative PCR and Western blotting were used to detect and analyze the difference of KRT79 gene and protein expression in the skin of Hetian sheep treated with different concentrations of testosterone.Immunofluorescence staining was used to explore the effect of testosterone on the expression distribution of KRT79 protein in the skin of Hetian sheep. 【Result】 The CDS region sequence length of KRT79 gene in Hetian sheep was 1 614 bp.The similarity of KRT79 gene sequence was 99.9% between Hetian sheep and Ovis aries.Phylogenetic tree analysis demonstrated that KRT79 gene had the closest evolutionary kindred with Ovis aries and the farthest evolutionary kindred with Mus musculus.KRT79 gene encoded 537 amino acids,which was an unstable hydrophilic protein,and the secondary structure of KRT79 protein was mainly comprised of alpha helix and random coil.The results of morphological analysis showed that the area of sebaceous glands in the skin of Hetian sheep expanded after testosterone treatment,and the number raised.Real-time quantitative PCR,Western blotting and immunofluorescence results indicated that the expression of KRT79 gene and protein in the skin of Hetian sheep were significantly higher than that in control group after testosterone treatment (P＜0.05).KRT79 protein was mainly distributed in the sebaceous glands,epidermis,and hair follicle areas of the skin in Hetian sheep. 【Conclusion】 The CDS region of KRT79 gene in Hetian sheep was 1 614 bp,and was an unstable hydrophilic protein.Androgen stimulation could significantly promote an increase in the area and quantity of sebaceous glands in the skin of Hetian sheep,and promote the expression of KRT79 gene and protein in the skin.This results provided a theoretical basis for further exploring the effects and mechanisms of androgens on the skin in Hetian sheep,and also provided a reference for the development of treatment methods for skin lipid metabolism abnormalities and keratin imbalance diseases caused by androgens.

Key words: Hetian sheep; KRT79 gene; skin; sebaceous glands; androgens