Sun Penghao, Wang Hongliang, Liu Lingyun, Guo Kaimin, Li Xian, Cao Yin, Ko Chemyong, Lan Zi-Jian, Lei Zhenmin
Department of Andrology, The First Hospital of Jilin University, Changchun, China.
Department of OB/GYN, University of Louisville School of Medicine, Louisville, KY, United States.
Front Physiol. 2022 Aug 19;13:991719. doi: 10.3389/fphys.2022.991719. eCollection 2022.
KRAS plays critical roles in regulating a range of normal cellular events as well as pathological processes in many tissues mediated through a variety of signaling pathways, including ERK1/2 and AKT signaling, in a cell-, context- and development-dependent manner. The function of KRAS and its downstream targets in gonadal steroidogenic cells for the development and homeostasis of reproductive functions remain to be determined. To understand the functions of KRAS signaling in gonadal theca and interstitial cells, we generated a mutant () mouse line that selectively expressed a constitutively active in these cells. expression in ovarian theca cells did not block follicle development to the preovulatory stage. However, females failed to ovulate and thus were infertile. The phosphorylated ERK1/2 and forkhead box O1 (FOXO1) and total FOXO1 protein levels were markedly reduced in theca cells. expression in theca cells also curtailed the phosphorylation of ERK1/2 and altered the expression of several ovulation-related genes in gonadotropin-primed granulosa cells. To uncover downstream targets of KRAS/FOXO1 signaling in theca cells, we found that the expression of bone morphogenic protein 7 (), a theca-specific factor involved in ovulation, was significantly elevated in theca cells. Chromosome immunoprecipitation assays demonstrated that FOXO1 interacted with the promoter containing forkhead response elements and that the binding activity was attenuated in theca cells. Moreover, knockdown caused an elevation, whereas overexpression resulted in an inhibition of expression, suggesting that KRAS signaling regulates FOXO1 protein levels to control expression in theca cells. Thus, the anovulation phenotype observed in mice may be attributed to aberrant KRAS/FOXO1/BMP7 signaling in theca cells. Our work provides the first evidence that maintaining normal KRAS activity in ovarian theca cells is crucial for ovulation and female fertility.
KRAS在调节一系列正常细胞事件以及许多组织中的病理过程中发挥着关键作用，这些过程通过多种信号通路介导，包括ERK1/2和AKT信号通路，其作用方式取决于细胞、环境和发育阶段。KRAS及其下游靶点在性腺类固醇生成细胞中对生殖功能的发育和稳态的作用仍有待确定。为了了解KRAS信号在性腺膜细胞和间质细胞中的功能，我们构建了一种突变（）小鼠品系，该品系在这些细胞中选择性表达组成型激活的。在卵巢膜细胞中的表达并未阻止卵泡发育到排卵前阶段。然而，雌性小鼠无法排卵，因此不育。在膜细胞中，磷酸化的ERK1/2和叉头框O1（FOXO1）以及总FOXO1蛋白水平显著降低。在膜细胞中的表达还减少了ERK1/2的磷酸化，并改变了促性腺激素刺激的颗粒细胞中几种排卵相关基因的表达。为了揭示膜细胞中KRAS/FOXO1信号的下游靶点，我们发现骨形态发生蛋白7（）的表达在膜细胞中显著升高，是一种参与排卵的膜细胞特异性因子。染色体免疫沉淀分析表明，FOXO1与含有叉头反应元件的启动子相互作用，并且在膜细胞中这种结合活性减弱。此外，敲低导致升高，而过表达则导致表达受到抑制，这表明KRAS信号通过调节FOXO1蛋白水平来控制膜细胞中的表达。因此，在小鼠中观察到的无排卵表型可能归因于膜细胞中异常的KRAS/FOXO1/BMP7信号。我们的工作提供了首个证据，即维持卵巢膜细胞中正常的KRAS活性对于排卵和雌性生育能力至关重要。
