Bai Long, Chu Guiyan, Wang Wusu, Xiang Aoqi, Yang Gongshe
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, PR China.
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, PR China.
Theriogenology. 2017 Sep 15;100:24-31. doi: 10.1016/j.theriogenology.2017.05.022. Epub 2017 May 28.
Transforming growth factor β (TGF-β), acting as the auto/para endocrine factors, has multi-function in mammalian follicle development. Bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) is considered as a pseudoreceptor in the TGF-β signal pathway which has the similar extracellular structure of TGF-β receptor but lack of intracellular serine/threonine kinase domains. However, the biological function of BAMBI involved in porcine granulosa cell steroidogenesis remains unknown. This study was thus carried out to explore the effect of BAMBI on the steroidogenesis process in porcine primary granulosa cells. Our results showed overexpression of BAMBI promoted aromatase and StAR, but not P450scc and 3β-HSD mRNA and protein expression levels in porcine primary granulosa cells, and increased the accumulation of estradiol and progesterone in the culture medium. Meanwhile, knockdown endogenous BAMBI decreased the mRNA expression levels of Cyp19a1 and Star and the accumulation levels of estradiol and progesterone. TGF-β1 could decrease Cyp19a1 and Star mRNA expression and estradiol and progesterone production in a dose-dependent manner. Pre-treatment with BAMBI adenovirus reversed TGFβ1-induced downregulation of Cyp19a1 and Star mRNA expression. Moreover, TGF-β1 could induce the phosphorylation of SMAD3 in porcine granulosa cells. Pre-transfected with BAMBI adenovirus also inhibited TGF-β1-induced downregulation of estradiol and progesterone production as well as TGF-β1-induced phosphorylation of SMAD3 in porcine granulosa cells. These findings provided a potential mechanism by which BAMBI could regulate porcine granulosa cell steroidogenesis.
转化生长因子β（TGF-β）作为自分泌/旁分泌因子，在哺乳动物卵泡发育中具有多种功能。骨形态发生蛋白与激活素膜结合抑制剂（BAMBI）被认为是TGF-β信号通路中的一种假受体，其具有与TGF-β受体相似的细胞外结构，但缺乏细胞内丝氨酸/苏氨酸激酶结构域。然而，BAMBI参与猪颗粒细胞类固醇生成的生物学功能仍不清楚。因此，本研究旨在探讨BAMBI对猪原代颗粒细胞类固醇生成过程的影响。我们的结果表明，BAMBI的过表达促进了猪原代颗粒细胞中芳香化酶和类固醇生成急性调节蛋白（StAR）的表达，但不影响细胞色素P450侧链裂解酶（P450scc）和3β-羟基类固醇脱氢酶（3β-HSD）的mRNA和蛋白表达水平，并增加了培养基中雌二醇和孕酮的积累。同时，敲低内源性BAMBI可降低细胞色素P450芳香化酶1（Cyp19a1）和StAR的mRNA表达水平以及雌二醇和孕酮的积累水平。TGF-β1可呈剂量依赖性地降低Cyp19a1和StAR的mRNA表达以及雌二醇和孕酮的产生。用BAMBI腺病毒预处理可逆转TGF-β1诱导的Cyp19a1和StAR mRNA表达下调。此外，TGF-β1可诱导猪颗粒细胞中SMAD3的磷酸化。用BAMBI腺病毒预转染也可抑制TGF-β1诱导的猪颗粒细胞中雌二醇和孕酮产生的下调以及TGF-β1诱导的SMAD3磷酸化。这些发现提供了一种BAMBI调节猪颗粒细胞类固醇生成的潜在机制。
