FSH DIRECTED SIGNALING IN GRANULOSA CELLS--ROLE OF AKAP

颗粒细胞从未成熟到成熟表型的分化 受FSH刺激的cAMP依赖性蛋白激酶激活的调节 （PKA）.虽然一些早期和许多晚期反应基因已被确定， 在未成熟颗粒细胞PKA的下游， 除了PKA之外，导致这些基因激活的机制还知之甚少。 我们已经确定在未成熟细胞中，FSH直接激活PKA， 磷酸化核蛋白组蛋白H3和PKA促进 p38和p42/44丝裂原活化蛋白的独特活化 激酶（MAPK）途径;这些途径在大多数其他 细胞成熟颗粒细胞中PKA的激活（LH）类似 促进p42/44 MAPK途径的激活和磷酸化 组蛋白3，但如其他人所示，导致下调的一些 在未成熟颗粒细胞中激活的晚期反应基因和向上- 调节其他蛋白质。最近的研究表明， PKA（a）的位置是磷酸化的关键决定因素， 合适的靶蛋白，和（B）通过与A- 激酶锚定蛋白（AKAP）。我们假设 颗粒细胞对PKA的反应，如MAPK激活，和不同的 未成熟细胞与成熟细胞之间的反应部分由 一种或多种AKAP的特异性表达。为了支持这一假设， 我们已经证明FSH促进80 kDA AKAP的诱导， 其优先结合RII α，并且AKAP 80的表达 促进PKAII α在成熟颗粒细胞中的再分布。旨在 这项建议将测试的假设，FSH的行动，在不成熟的 颗粒细胞需要PKA锚定AKAP; FSH诱导的 80 kDA AKAP是一种独特的蛋白质，它与PKAII α共定位于 排卵前颗粒细胞; PKA需要AKAP 80， 激活成熟颗粒细胞的特征性反应;这种基本的 了解颗粒细胞中cAMP/PKA信号传导的方式， 为了解调节排卵的途径提供见解 和黄体化，这可以转化为更安全，更有效的 治疗不孕症和早孕流产。

Differentiation of granulosa cells from an immature to a mature phenotype is regulated by FSH-stimulated activation of cAMP-dependent protein kinase (PKA). While some early and many late response genes have been identified downstream of PKA in immature granulosa cells, the signaling pathways beyond PKA which lead to activation of these genes are poorly understood. We have determined in immature cells that FSH-activated PKA directly phosphorylates the nuclear protein histone H3 and that PKA promotes the unique activation of both the p38 and p42/44 mitogen activated protein kinase (MAPK) pathways; these pathways are inhibited by cAMP in most other cells. Activation of PKA in mature granulosa cells (by LH) similarly promotes activation of the p42/44 MAPK pathway and phosphorylation of histone 3, but as shown by others, leads to down-regulation of some of the late response genes activated in immature granulosa cells and up- regulation of other proteins. Recent studies suggest that the cellular location of PKA (a) is a critical determinant for phosphorylation of appropriate target proteins and (b) is regulated by association with A- kinase anchoring proteins (AKAPs). We hypothesize that the unique responses of granulosa cells to PKA, like MAPK activation, and distinct responses between immature versus mature cells are mediated in part by specific expression of one or more AKAPs. In support of this hypothesis, we have demonstrated that FSH promotes the induction of an 80 kDA AKAP which preferentially binds RIIalpha, and that expression of AKAP 80 promotes the redistribution of PKAIIalpha in mature granulosa cells. Aims of this proposal will test the hypotheses that actions of FSH in immature granulosa cells require anchoring of PKA to AKAPs; that the FSH-inducible 80 kDA AKAP is a unique protein which co-localizes with PKAIIalpha in preovulatory granulosa cells; and that AKAP 80 is required for PKA to activate responses characteristic of mature granulosa cells; This basic knowledge of how cAMP/PKA signals in granulosa cells is expected to provide insights towards understanding pathways which regulate ovulation and luteinization and which can translate into safer and more effective treatments of infertility and early pregnancy loss.