T-2 toxin regulates steroid hormone secretion of rat ovarian granulosa cells through cAMP-PKA pathway
T-2 toxin regulates steroid hormone secretion of rat ovarian granulosa cells through cAMP-PKA pathway
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T-2毒素通过cAMP-PKA通路调节大鼠卵巢颗粒细胞类固醇激素分泌
DOI：
10.1016/j.toxlet.2014.12.016
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发表时间：
2015-02-03
影响因子：
3.5
通讯作者：
Tian, Yanan
中科院分区：
文献类型：
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作者：
Wu, Jing;Tu, Di;Tian, Yanan
T-2毒素是由镰刀菌属产生的次生代谢物，是谷类食品和饲料中常见的污染物。在猪颗粒细胞(GC)中，T-2毒素具有抑制类固醇合成的作用，但其作用机制尚不清楚。促性腺激素刺激的类固醇合成受cAMP-PKA途径的调节。在本研究中，我们重点研究了T-2毒素影响cAMP-PKA途径的关键步骤，探讨了T-2毒素诱导生殖毒性的可能机制。我们首先分析了T-2毒素对大鼠颗粒细胞孕酮和雌激素产生的影响。为此，颗粒细胞在含10%胎牛血清的培养液中培养48h，然后在含有FSH(10 ng/ml)和雄烯二酮(3 ng/ml)的无血清培养液中培养24 h，这两种激素都是正常类固醇合成所必需的。用T-2毒素处理这些细胞可剂量依赖性地抑制细胞生长和类固醇激素的产生。T-2毒素(0、1、10和100 nM，24 h)呈剂量依赖性抑制细胞内cAMP水平。此外，我们还发现，虽然T-2毒素可抑制8-Br-cAMP(FSH模拟物)和22R-HC(孕酮底物)对孕酮的诱导作用，但增加22R-HC的剂量可逆转T-2的抑制作用，而增加8-Br-cAMP的作用则不起作用，提示T2毒素的作用机制不同。CAMP刺激的类固醇合成急性调节蛋白(STAR)是孕酮合成的限速蛋白。经Western blotting和半定量RT-PCR检测，T2毒素可显着抑制STAR的表达，提示STAR是T-2毒素的敏感靶点。综上所述，我们的结果强烈表明T2毒素通过抑制cAMP-PKA途径来抑制类固醇的生成，而STAR是T-2-毒素的靶标。T-2毒素在低剂量(1 ng/ml)时有抗类固醇生成作用，提示T-2毒素具有内分泌干扰作用。(C)2014爱思唯尔爱尔兰有限公司。保留所有权利。
T-2 toxin is a secondary metabolite produced by Fusarium genus and is a common contaminant in food and feedstuffs of cereal origin. In porcine granulosa cells(GC), T-2 toxin has been shown to inhibit the steroidogenesis; however, the mechanism has not been well understood. Gonadotropin-stimulated steroidogenesis is regulated by the cAMP-PKA pathway. In this study, we investigated potential mechanisms for T-2 toxin-induced reproductive toxicity focusing on the critical steps of the cAMP-PKA pathway affected by T-2 toxin. We first analyzed the effects of T-2 toxin on progesterone and estrogen production in rat granulosa cells. For this purpose the granulosa cells were cultured for 48 h in 10% fetal bovine serum-containing medium followed by 24 h in serum-free medium containing FSH (10 ng/ml) and androstenedione (3 ng/ml), both are required for normal steroidogenesis. Treatment of these cells with T-2 toxin dose-dependently inhibited the growth of cells and the steroid hormone production. Cellular cyclic AMP levels were dose-dependently inhibited by T-2 toxin (0, 1, 10 and 100 nM, 24 h). Furthermore, we found that although the induction of progesterone by 8-Br-cAMP (a FSH mimetic) and 22R-HC (substrate for progesterone) could both be inhibited by T-2 toxin treatment, the T-2-imposed inhibitory effects could be reversed by increasing doses of 22R-HC, while increasing 8-Br-cAMP had no effects, suggesting that T2 toxin targeted at distinct mechanisms. cAMP-stimulated steroidogenic acute regulatory protein (StAR) is a rate limiting protein in progesterone synthesis. Exposure to T2 toxin caused significant suppression of StAR expression as determined by Western blotting and semi-quantitative RT-PCR suggesting StAR is a sensitive target for T-2 toxin. Taken together, our results strongly suggest that T2 toxin inhibits steroidogenesis by suppressing cAMP-PKA pathway and StAR is a target for T-2-toxin. The antisteroidogenesis effects were observable at low T-2 dose (1 ng/ml) suggesting T-2 toxin has an endocrine disruptive effect. (C) 2014 Elsevier Ireland Ltd. All rights reserved.