Unité de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, F-37 380 Nouzilly, France Unité de Recherches Avicoles, INRA, URA83, F-37 380 Nouzilly, France.
Reproduction. 2010 Feb;139(2):409-18. doi: 10.1530/REP-09-0351. Epub 2009 Nov 11.
Although its mechanism of action is still unclear, metformin is an anti-diabetic drug effective to restore cyclicity and spontaneous ovulation in women with polycystic ovary syndrome. It may also reduce the risk of cancer. We have recently shown that metformin treatment decreases steroidogenesis through AMP-activated kinase (AMPK) in granulosa cells of various species. Here, we investigated the effects and the molecular mechanisms of metformin in IGF1-induced proliferation and protein synthesis in cultured bovine granulosa cells. Treatment with metformin (10 mM) for 24 h reduced cell proliferation and the levels of cyclin D2 and E, and increased the associations cyclin D2/p21 and cyclin D2/p27 without affecting cell viability in response to IGF1 (10(-8) M). It also decreased IGF1-induced protein synthesis and phosphorylation of P70S6 kinase and ribosomal S6 protein. Interestingly, metformin treatment for 1 h decreased MAPK3/1 (ERK1/2) and P90RSK phosphorylation without affecting AKT phosphorylation in response to IGF1. Adenovirus-mediated expression of dominant-negative AMPK totally abolished the effects of metformin on cell proliferation and phosphorylation of P70S6K in response to IGF1. It also eliminated the inhibitory effects of metformin on MAPK3/1 and P90RSK phosphorylation. Taken together, our results strongly suggest that metformin reduces cell growth, protein synthesis, MAPK3/1, and P90RSK phosphorylation in response to IGF1 through an AMPK-dependent mechanism in cultured bovine granulosa cells.
虽然其作用机制尚不清楚，但二甲双胍是一种抗糖尿病药物，可有效恢复多囊卵巢综合征妇女的周期性和自发性排卵。它还可能降低癌症风险。我们最近表明，二甲双胍通过 AMP 激活的蛋白激酶（AMPK）在各种物种的颗粒细胞中降低类固醇生成。在这里，我们研究了二甲双胍在 IGF1 诱导的培养牛颗粒细胞增殖和蛋白质合成中的作用及其分子机制。二甲双胍（10mM）处理 24 小时可降低细胞增殖和细胞周期蛋白 D2 和 E 的水平，并增加细胞周期蛋白 D2/p21 和细胞周期蛋白 D2/p27 的关联，而对 IGF1（10(-8)M）的细胞活力无影响。它还降低了 IGF1 诱导的蛋白质合成和 P70S6 激酶和核糖体 S6 蛋白的磷酸化。有趣的是，二甲双胍处理 1 小时可降低 MAPK3/1（ERK1/2）和 P90RSK 的磷酸化，而对 IGF1 反应中的 AKT 磷酸化无影响。腺病毒介导的显性失活 AMPK 的表达完全消除了二甲双胍对 IGF1 反应中细胞增殖和 P70S6K 磷酸化的影响。它还消除了二甲双胍对 MAPK3/1 和 P90RSK 磷酸化的抑制作用。总之，我们的结果强烈表明，二甲双胍通过培养牛颗粒细胞中的 AMPK 依赖性机制降低 IGF1 反应中的细胞生长、蛋白质合成、MAPK3/1 和 P90RSK 磷酸化。
