DeManno D A, Cottom J E, Kline M P, Peters C A, Maizels E T, Hunzicker-Dunn M
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA.
Mol Endocrinol. 1999 Jan;13(1):91-105. doi: 10.1210/mend.13.1.0222.
FSH promoted the rapid phosphorylation of the nuclear protein histone H3 in immature rat ovarian granulosa cells under experimental conditions that lead to cellular differentiation and not proliferation. FSH-stimulated histone H3 phosphorylation correlated with cAMP-dependent protein kinase A (PKA) activation and translocation of the PKA catalytic subunit to a nuclear-enriched fraction and was inhibited by the PKA inhibitor H89, and histone H3 phosphorylation was stimulated in cells treated with agents that raise intracellular cAMP levels such as forskolin and 8-bromo-cAMP. FSH-stimulated histone H3 phosphorylation in granulosa cells mapped to ser-10, a site previously identified as the PKA phosphorylation site in various mitotically active cells as the mitosis-specific phosphorylation site. Injection of the FSH analog PMSG to immature rats, which is known to stimulate granulosa cell proliferation as well as differentiation, also promoted histone H3 phosphorylation on ser-10 in granulosa cells. These results establish that FSH-stimulated histone H3 phosphorylation in granulosa cells is linked not only to granulosa cell mitosis but also to granulosa cell differentiation and that FSH-stimulated histone H3 phosphorylation on ser-10 in isolated granulosa cells is mediated by PKA. These results also identify the PKA-dependent histone H3 phosphorylation as an early nuclear protein marker for FSH-stimulated differentiation of granulosa cells. Based on the recently described function of histone H3 as a coactivator of transcription, these results are consistent with the hypothesis that phosphorylated histone H3 may facilitate PKA-dependent gene transcription in granulosa cells leading to the preovulatory phenotype.
在导致细胞分化而非增殖的实验条件下，促卵泡激素（FSH）促进未成熟大鼠卵巢颗粒细胞中核蛋白组蛋白H3的快速磷酸化。FSH刺激的组蛋白H3磷酸化与环磷酸腺苷（cAMP）依赖性蛋白激酶A（PKA）的激活以及PKA催化亚基向富含核的部分的转位相关，并被PKA抑制剂H89抑制，在用提高细胞内cAMP水平的试剂（如福斯可林和8-溴-cAMP）处理的细胞中，组蛋白H3磷酸化受到刺激。FSH刺激的颗粒细胞中组蛋白H3磷酸化定位于丝氨酸10，该位点先前在各种有丝分裂活跃细胞中被确定为PKA磷酸化位点，作为有丝分裂特异性磷酸化位点。向未成熟大鼠注射已知能刺激颗粒细胞增殖以及分化的FSH类似物孕马血清促性腺激素（PMSG），也促进了颗粒细胞中丝氨酸10处的组蛋白H3磷酸化。这些结果表明，FSH刺激的颗粒细胞中组蛋白H3磷酸化不仅与颗粒细胞有丝分裂有关，还与颗粒细胞分化有关，并且FSH刺激的分离颗粒细胞中丝氨酸10处的组蛋白H3磷酸化是由PKA介导的。这些结果还将PKA依赖性组蛋白H3磷酸化鉴定为FSH刺激的颗粒细胞分化的早期核蛋白标志物。基于最近描述的组蛋白H3作为转录共激活因子的功能，这些结果与以下假设一致：磷酸化的组蛋白H3可能促进颗粒细胞中PKA依赖性基因转录，从而导致排卵前表型。
