Follicle-stimulating hormone induces multiple signaling cascades: Evidence that activation of Rous sarcoma oncogene, RAS, and the epidermal growth factor receptor are critical for granulosa cell differentiation
Follicle-stimulating hormone induces multiple signaling cascades: Evidence that activation of Rous sarcoma oncogene, RAS, and the epidermal growth factor receptor are critical for granulosa cell differentiation
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DOI：
10.1210/me.2007-0020
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发表时间：
2007-08-01
影响因子：
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通讯作者：
Richards, JoAnne S.
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文献类型：
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作者：
Wayne, Chad M.;Fan, Heng-Yu;Richards, JoAnne S.
FSH不仅通过激活腺苷酸环化酶和蛋白激酶A（PKA）调节卵巢颗粒细胞的分化，而且还通过其他复杂的机制。使用原代大鼠颗粒细胞培养，我们提供了新的证据，FSH快速激活两个小的GTP结合蛋白RAP 1和RAS。FSH激活RAP 1需要cAMP介导的cAMP/RAPGEF 3激活的交换因子的激活，而FSH激活RAS和下游信号级联涉及多种因素。具体而言，FSH激活RAS需要劳斯肉瘤癌基因（SRC）家族酪氨酸激酶（SFK）和表皮生长因子受体（EGFR）酪氨酸激酶活性，但不需要PKA。FSH诱导的ERK 1/2磷酸化被显性负性RAS以及EGFR酪氨酸激酶、参与生长因子脱落的金属蛋白酶和SFKs抑制剂阻断。相反，FSH诱导的蛋白激酶B（PKB/AKT）和叉头转录因子FOXO 1a的磷酸化通过SFK依赖性但RAS独立性机制发生。SFKs，c-SRC和FYN，以及SRC相关的酪氨酸激酶ABL的存在和磷酸化迅速响应FSH。最后，表皮生长因子样因子双调蛋白（AREG）激活RAS和ERK 1/2磷酸化的颗粒细胞的机制，选择性地阻断EGFR拮抗剂，但不是由SFK拮抗剂。然而，AREG介导的PKB和FOXO 1a磷酸化需要EGFR和SFK激活。此外，我们发现FSH诱导AREG，EGFR的激活影响颗粒细胞分化和黄体细胞表型特征基因的表达。因此，FSH协调三种不同的膜相关信号级联（腺苷酸环化酶，RAS和SFKs）的协调激活，这些级联在下游会聚以激活控制颗粒细胞功能和分化的特定激酶（PKA，ERK 1/2和PKB/FOXO 1a）。
FSH regulates ovarian granulosa cell differentiation not only by activating adenylyl cyclase and protein kinase A (PKA) but also by other complex mechanisms. Using primary rat granulosa cell cultures, we provide novel evidence that FSH rapidly activates two small GTP-binding proteins RAP1 and RAS. FSH activation of RAP1 requires cAMP-mediated activation of exchange factor activated by cAMP/RAPGEF3 whereas FSH activation of RAS and downstream signaling cascades involves multiple factors. Specifically, FSH activation of RAS required Rous sarcoma oncogene (SRC) family tyrosine kinase (SFK) and epidermal growth factor receptor (EGFR) tyrosine kinase activities but not PKA. FSH-induced phosphorylation of ERK1/2 was blocked by dominant-negative RAS as well as by inhibitors of EGFR tyrosine kinase, metalloproteinases involved in growth factor shedding, and SFKs. In contrast, FSH-induced phosphorylation of protein kinase B (PKB/AKT) and the Forkhead transcription factor, FOXO1a occurred by SFK-dependent but RAS-independent mechanisms. The SFKs, c-SRC and FYN, and the SRC-related tyrosine kinase ABL were present and phosphorylated rapidly in response to FSH. Lastly, the EGF-like factor amphiregulin (AREG) activated RAS and ERK1/2 phosphorylation in granulosa cells by mechanisms that were selectively blocked by an EGFR antagonist but not by an SFK antagonist. However, AREG-mediated phosphorylation of PKB and FOXO1a required both EGFR and SFK activation. Moreover, we show that FSH induces AREG and that activation of the EGFR impacts granulosa cell differentiation and the expression of genes characteristic of the luteal cell phenotype. Thus, FSH orchestrates the coordinate activation of three diverse membrane-associated signaling cascades (adenylyl cyclase, RAS, and SFKs) that converge downstream to activate specific kinases (PKA, ERK1/2, and PKB/FOXO1a) that control granulosa cell function and differentiation.