FSH DIRECTED SIGNALING IN GRANULOSA CELLS--ROLE OF AKAP

颗粒细胞从未成熟表型向成熟表型的分化 受FSH刺激的cAMP依赖的蛋白激酶激活所调节 (PKA)。虽然已经发现了一些早期反应基因和许多晚期反应基因 在未成熟颗粒细胞中，PKA下游的信号通路 除了PKA以外，导致这些基因激活的机制还知之甚少。 我们已经在未成熟的细胞中确定FSH直接激活PKA 使核蛋白组蛋白H3磷酸化，PKA促进 P38和p42/44丝裂原激活蛋白的独特激活 激酶(MAPK)途径；在大多数其他途径中，这些途径被cAMP抑制 细胞。成熟颗粒细胞中PKA的激活(由黄体生成素激活)类似 促进p42/44 MAPK通路的激活和磷酸化 组蛋白3，但如其他人所示，导致一些基因的下调。 晚反应基因在未成熟的颗粒细胞中被激活，而UP-1 对其他蛋白质的调节。最近的研究表明，细胞 PKA(A)的位置是磷酸化的关键决定因素 适当的靶蛋白和(B)通过与A- 激酶锚定蛋白(AKAP)。我们假设独一无二的 颗粒细胞对PKA的反应，如MAPK激活，以及不同的 未成熟细胞和成熟细胞之间的反应部分是通过 一个或多个AKAP的特定表达。为了支持这一假设， 我们已经证明，FSH促进80kda AKAP的诱导 其优先结合RIIpha和AKAP 80的表达 促进PKAIIpha在成熟颗粒细胞中的重新分布。目标 这一提议的提出将检验FSH在未成熟阶段的作用 颗粒细胞需要将PKA锚定到AKAP上；FSH诱导的 80KDA AKAP是一种独特的蛋白，它与PKAIIpha共定位于 排卵前颗粒细胞；PKA需要AKAP 80 激活成熟颗粒细胞特有的反应；这是基本的 颗粒细胞中cAMP/PKA信号的预期 为了解调节排卵的途径提供了见解 和黄体生成素，这可以转化为更安全和更有效的 不孕不育和早孕丢失的治疗。

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.