Unité de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, UMR85, F-37380 Nouzilly, France.
Mol Hum Reprod. 2013 May;19(5):313-26. doi: 10.1093/molehr/gat002. Epub 2013 Jan 11.
Visfatin is a cytokine hormone and an enzyme involved in metabolic (obesity, type II diabetes) and immune disorders. Some data suggest a role of visfatin in ovarian function. Here, we identified visfatin in human follicles and investigated the molecular mechanisms involved in the regulation of its expression in response to insulin sensitizers, metformin (MetF) and rosiglitazone, in primary human granulosa cells (hGCs) and in a human ovarian granulosa-like tumour cell line (KGN). We also studied the effects of human recombinant visfatin (RhVisf) on steroid production and on the activation of various signalling pathways. By RT-PCR, immunoblotting and immunohistochemistry, we showed that visfatin is expressed not only in hGCs and KGN cells, but also in human cumulus cells and oocytes. In hGCs and KGN cells, MetF increased visfatin mRNA in a dose-dependent manner (0.1, 1 and 10 mM), and rosiglitazone increased visfatin mRNA expression (only at 10 μM) after treatments for 24 h, whereas both reduced it after 48 h of incubation. This regulation was confirmed at the protein level for the MetF treatment only. Using the compound C and Aicar, inhibitor and activator of AMP-activated protein kinase (AMPK), respectively, and Sirtinol, an inhibitor of sirtuin-1 (SIRT1), we observed that these MetF effects on visfatin expression were mediated through the AMPK/SIRT1 signalling pathways. RhVisf (10 ng/ml) significantly increased insulin-like growth factor-1 (IGF-1) (10 nM)- but not FSH (10 nM)-induced secretion of progesterone and estradiol as determined by radioimmunoassay and IGF-1-induced thymidine incorporation in hGCs and KGN cells. Finally, rhVisf rapidly activates the mitogen-activated protein kinase pathway via ERK1/2, P38 and Akt phosphorylation under basal conditions in primary hGC cells. In conclusion, visfatin is present in ovarian human follicles, and in hGCs and KGN cells, visfatin increases IGF-1-induced steroidogenesis and cell proliferation and MetF regulates visfatin expression through the AMPK/SIRT1 signalling pathway.
内脂素是一种细胞因子激素和一种参与代谢（肥胖、2 型糖尿病）和免疫紊乱的酶。一些数据表明内脂素在卵巢功能中起作用。在这里，我们在人类卵泡中鉴定了内脂素，并研究了在胰岛素增敏剂二甲双胍（MetF）和罗格列酮作用下，其表达受到调节的分子机制，在原代人颗粒细胞（hGCs）和人卵巢颗粒样肿瘤细胞系（KGN）中。我们还研究了人重组内脂素（RhVisf）对类固醇产生和各种信号通路激活的影响。通过 RT-PCR、免疫印迹和免疫组织化学，我们表明内脂素不仅在 hGCs 和 KGN 细胞中表达，而且在人卵丘细胞和卵母细胞中表达。在 hGCs 和 KGN 细胞中，MetF 以剂量依赖性方式增加内脂素 mRNA（0.1、1 和 10 mM），并且在 24 小时处理后增加内脂素 mRNA 表达（仅在 10 μM 时），而在孵育 48 小时后两者均降低。这种调节仅在 MetF 处理时在蛋白质水平上得到证实。使用化合物 C 和 Aicar，分别为 AMP 激活蛋白激酶（AMPK）的抑制剂和激活剂，以及 Sirtinol，一种 Sirtuin-1（SIRT1）的抑制剂，我们观察到 MetF 对内脂素表达的这些影响是通过 AMPK/SIRT1 信号通路介导的。RhVisf（10 ng/ml）显著增加胰岛素样生长因子-1（IGF-1）（10 nM）-但不是促卵泡激素（FSH）（10 nM）诱导的孕酮和雌二醇的分泌，如放射免疫测定法和 IGF-1 在 hGCs 和 KGN 细胞中诱导的胸苷掺入所确定的。最后，rhVisf 在原代 hGC 细胞中，在基础条件下，通过 ERK1/2、P38 和 Akt 磷酸化迅速激活丝裂原激活蛋白激酶途径。总之，内脂素存在于卵巢人类卵泡中，并且在 hGCs 和 KGN 细胞中，内脂素增加 IGF-1 诱导的类固醇生成和细胞增殖，MetF 通过 AMPK/SIRT1 信号通路调节内脂素表达。
