Zheng Hang, Li Hong, Tan Wenbo, Xu Chunlin, Jia Lijuan, Wang Dandan, Li Zhuanjian, Sun Gunrong, Kang Xiangtao, Yan Fengbin, Liu Xiaojun
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, People's Republic of China.
J Genet. 2018 Mar;97(1):145-155.
The cathepsin E-A-like, also known as 'similar to nothepsin', is a new member of the aspartic protease family, which may take part in processing of egg yolk macromolecules, due to it was identified in the chicken egg-yolk. Previously, studies have suggested that the expression of cathepsin E-A-like increased gradually during sexual maturation of pullets, but the exact regulation mechanism is poorly understood. In this study, to gain insight into the function and regulation mechanism of the gene in egg-laying hen, we cloned the cathepsin E-A-like gene and evaluated its evolutionary origin by using both phylogenetic and syntenic methods. The mode of the gene expression regulation was analysed through stimulating juvenile hens with 17β-estradiol and chicken embryo hepatocytes with 17β-estradiol combined with oestrogen receptor antagonists including MPP, ICI 182,780 and tamoxifen. Our results showed that cathepsin E-A-like was an orthologoues gene with nothepsin, which is present in birds but not in mammals. The expression of cathepsin E-A-like significantly increased in a dose-dependent manner after the juvenile hens were treated with 17β-estradiol (P < 0.05). Compared with the 17β-estradiol treatment group, the expression of cathepsin E-A-like was not significantly changed when the hepatocytes were treated with 17β-estradiol combined with MPP (P < 0.05). In contrast, compared with the 17β-estradiol combined with MPP treatment group, the expression of cathepsin E-A-like was significantly downregulated when the hepatocytes were treated with 17β-estradiol combined with tamoxifen or ICI 182,780 (P < 0.05). These results demonstrated that cathepsin E-A-like shared the same evolutionary origin with nothepsin. The expression of cathepsin E-A-like was regulated by oestrogen, and the regulative effect was predominantly mediated through ER-Β in liver of chicken.
组织蛋白酶E-A样蛋白，也被称为“类诺特蛋白酶”，是天冬氨酸蛋白酶家族的一个新成员，由于它是在鸡蛋黄中被鉴定出来的，因此可能参与蛋黄大分子的加工过程。此前的研究表明，在小母鸡性成熟过程中，组织蛋白酶E-A样蛋白的表达逐渐增加，但具体的调控机制尚不清楚。在本研究中，为了深入了解该基因在产蛋母鸡中的功能和调控机制，我们克隆了组织蛋白酶E-A样蛋白基因，并通过系统发育和共线性方法评估了其进化起源。通过用17β-雌二醇刺激幼年母鸡以及用17β-雌二醇联合包括MPP、ICI 182,780和他莫昔芬在内的雌激素受体拮抗剂刺激鸡胚肝细胞，分析了该基因的表达调控模式。我们的结果表明，组织蛋白酶E-A样蛋白是诺特蛋白酶的直系同源基因，存在于鸟类而非哺乳动物中。用17β-雌二醇处理幼年母鸡后，组织蛋白酶E-A样蛋白的表达呈剂量依赖性显著增加（P<0.05）。与17β-雌二醇处理组相比，用17β-雌二醇联合MPP处理肝细胞时，组织蛋白酶E-A样蛋白的表达没有显著变化（P<0.05）。相反，与17β-雌二醇联合MPP处理组相比，用17β-雌二醇联合他莫昔芬或ICI 182,780处理肝细胞时，组织蛋白酶E-A样蛋白 的表达显著下调（P<0.05）。这些结果表明，组织蛋白酶E-A样蛋白与诺特蛋白酶具有相同的进化起源。组织蛋白酶E-A样蛋白的表达受雌激素调控，且这种调控作用主要通过鸡肝脏中的雌激素受体β介导。
