CREB activity is required for mTORC1 signaling-induced primordial follicle activation in mice
CREB activity is required for mTORC1 signaling-induced primordial follicle activation in mice
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CREB 活性是 mTORC1 信号诱导小鼠原始卵泡激活所必需的
DOI：
10.1007/s00418-020-01888-4
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发表时间：
2020-06-03
影响因子：
2.3
通讯作者：
Zhang, Meijia
中科院分区：
文献类型：
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作者：
Li, Jia;Zhang, Yu;Zhang, Meijia
在哺乳动物中，原始卵泡的渐进激活对于维持生殖寿命是必不可少的。一些报道表明，颗粒前细胞中的丝裂原激活蛋白激酶3和1(MAPK3/1)-雷帕霉素复合体的哺乳动物靶标1(MTORC1)信号通过增加KITL的表达进而刺激卵母细胞中的磷脂酰肌醇3激酶信号通路来促进原始卵泡的激活。然而，mTORC1信号在促进KITL表达中的作用机制尚不清楚。免疫荧光染色结果显示，磷酸化的环磷酸腺苷反应元件结合蛋白(CREB)主要在颗粒前细胞表达。CREB抑制剂KG-501和CREB被Creb siRNA敲除可显著抑制原始卵泡的激活，减少颗粒前细胞的增殖，显著增加卵母细胞的凋亡率。Western blotting结果显示，MAPK3/1抑制剂U0126和mTORC1抑制剂雷帕霉素均能显著降低CREB的磷酸化水平，提示CREB的激活需要MAPK3/1-mTORC1信号通路。此外，CREB可与KITL启动子区域结合，KG-501显著降低KITL的表达水平。此外，KG-501和CREB基因敲除显著降低了Akt的磷酸化水平，导致带有Foxo3a核输出的卵母细胞数量减少。Kg-501还可抑制BPV(Hopic)刺激的原始卵泡激活。综上所述，这些结果表明，CREB是MAPK3/1-mTORC1信号促进KITL表达进而激活原始卵泡所必需的。
In mammals, progressive activation of primordial follicles is essential for maintenance of the reproductive lifespan. Several reports have demonstrated that mitogen-activated protein kinases 3 and 1 (MAPK3/1)-mammalian target of rapamycin complex 1 (mTORC1) signaling in pre-granulosa cells promotes primordial follicle activation by increasing KIT ligand (KITL) expression and then stimulating phosphatidylinositol 3 kinase signaling in oocytes. However, the mechanism of mTORC1 signaling in the promotion of KITL expression is unclear. Immunofluorescence staining results showed that phosphorylated cyclic AMP response element-binding protein (CREB) was mainly expressed in pre-granulosa cells. The CREB inhibitor KG-501 and CREB knockdown by Creb siRNA significantly suppressed primordial follicle activation, reduced pre-granulosa cell proliferation and dramatically increased oocyte apoptosis. Western blotting results demonstrated that both the MAPK3/1 inhibitor U0126 and mTORC1 inhibitor rapamycin significantly decreased the levels of phosphorylated CREB, indicating that MAPK3/1-mTORC1 signaling is required for CREB activation. Furthermore, CREB could bind to the Kitl promoter region, and KG-501 significantly decreased the expression levels of KITL. In addition, KG-501 and CREB knockdown significantly decreased the levels of phosphorylated Akt, leading to a reduced number of oocytes with Foxo3a nuclear export. KG-501 also inhibited bpV (HOpic)-stimulated primordial follicle activation. Taken together, the results show that CREB is required for MAPK3/1-mTORC1 signaling-promoted KITL expression followed by the activation of primordial follicles.