FSH-STIMULATED SIGNALS THAT REGULATE FOLLICULAR MATURATION

卵巢卵泡的生长是一个动态的过程，需要精细的调控。卵泡在窦前阶段被抑制，直到它们被卵泡刺激素（FSH）刺激。FSH通过cAMP和cAMP依赖性蛋白激酶（PKA）通过其细胞表面受体进行信号传导。通过特异性PKA抑制剂肽PKI阻断急性信号传导事件（例如组蛋白H3磷酸化和细胞外调节激酶ERK的活化）以及防止诱导排卵前表型发展所需的基因/蛋白质的能力，证明了对PKA的需求。然而，FSH刺激的 颗粒细胞成熟也被磷脂酰肌醇-3（PI-3）的化学抑制剂阻断 激酶途径PI-3激酶及其下游激酶靶AKT在结合衔接蛋白胰岛素受体底物（IRS）1/2后被胰岛素或胰岛素样生长因子1受体经典激活。FSH刺激的AKT磷酸化也被PKI阻断。我们假设PKA独特地协调所有FSH调节的信号通路来指导颗粒细胞分化。我们还假设FSH通过PI-3激酶途径通过诱导转录因子缺氧诱导因子-1 α（HIF-1 α）和抑制抑制颗粒细胞成熟的转录因子FKHR的信号来传递信号。在本研究中，我们将验证FSH通过PKA信号激活PI-3激酶的假说 FSH通过PI-3激酶诱导HIF-1 α，HIF-1 α是诱导FSH应答基因的关键正信号，FKHR通过PI-3激酶途径磷酸化，中和了维持颗粒细胞未分化状态的信号。因此，诱导表征成熟颗粒细胞的关键调控基因不仅需要通过CREB、组蛋白H3和ERK调节信号传导，还需要通过PI-3激酶靶向HIF-1 α和HIF-1a调节信号传导。 FKHR。了解卵泡成熟是如何调节的可以转化为更安全，更有效的生育治疗。

Ovarian follicle growth is a dynamic process that requires exquisite regulation. Follicles are restrained at the preantral stage until they are stimulated by follicle stimulating hormone (FSH). FSH signals through its cell-surface receptor via cAMP and cAMP-dependent protein kinase (PKA). The requirement for PKA is demonstrated by the ability of the specific PKA inhibitor peptide, PKI, to block acute signaling events, such as histone H3 phosphorylation and activation of the extracellular regulated kinase ERK, as well as to prevent induction of genes/proteins required for development of the preovulatory phenotype. However, FSH-stimulated granulosa cell maturation is also blocked by chemical inhibitors of the phosphoinositide-3 (PI-3) kinase pathway. PI-3 kinase and its downstream kinase target AKT are classically activated by the insulin or insulin-like growth factor 1 receptors upon binding the adaptor protein insulin receptor substrates (IRS) 1/2. FSH-stimulated AKT phosphorylation is also blocked by PKI. We hypothesize that PKA uniquely orchestrates all of the FSH-regulated signaling pathways to direct granulosa cell differentiation. We also hypothesize that FSH signals through the PI-3 kinase pathway by inducing the transcription factor hypoxia inducible factor-1alpha (HIF-1alpha) and inhibiting signals from the transcription factor FKHR that repress granulosa cell maturation. In this proposal we will test the hypotheses that FSH signals via PKA to activate PI-3 kinase via the adapters IRS1 and/or IRS2, that FSH via PI-3 kinase induces HIF-1alpha and that HIF-1alpha is a key positive signal leading to induction of FSH-responsive genes, and that signaling from FKHR which maintains granulosa cells in an undifferentiated state is neutralized by its phosphorylation via the PI-3 kinase pathway. Induction of key regulatory genes that characterize mature granulosa cells therefore requires regulated signaling not only through CREB, histone H3, and ERK but also through PI-3 kinase targets HIF-1alpha and FKHR. Understanding how follicular maturation is regulated can translate into safer and more effective treatments for fertility.