CELL CYCLE-DEPENDENT GLUCOCORTICOID RECEPTOR PHOSPHORYLATION AND ACTIVITY
CELL CYCLE-DEPENDENT GLUCOCORTICOID RECEPTOR PHOSPHORYLATION AND ACTIVITY
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DOI：
10.1210/me.8.12.1709
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发表时间：
1994-12-01
影响因子：
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通讯作者：
MUNCK, A
中科院分区：
文献类型：
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作者：
HU, JM;BODWELL, JE;MUNCK, A
增殖细胞对糖皮质激素基因激活的敏感性表现出明显的细胞周期依赖性；它们在GAP 1/合成晚期(G1/S)(G1和S)敏感，但在GAP 2/有丝分裂期(G2/M)耐受，我们描述了与细胞周期相关的糖皮质激素受体(GR)磷酸化的变化，这种变化伴随着并可能解释了敏感性的变化，GR在激素诱导激活后基本被磷酸化并经历过度磷酸化。鉴定出的磷酸化位点都在N-末端结构域。在一个区域需要几个IIE，以充分反式激活活性和减少与DNA的非特异性结合。大多数都是在细胞周期相关激酶的共同序列中发现的，这表明这种激酶可以磷酸化GRs，我们现在在WCL2细胞(GRS过表达的中国仓鼠卵巢细胞)中表明：1)糖皮质激素处理不能过度磷酸化G2/M中的GRS，但在S细胞中磷酸化倍增，比未同步的细胞更多；2)基础GR磷酸化在G2/M中几乎是S的三倍，这些结果与早期的观察结果一起，暗示GR磷酸化与糖皮质激素耐药在G2/M中的机制有关，这种机制可能是炎症性和淋巴增生性疾病中糖皮质激素耐药的基础。S和G2/M的GRs的高效液相色谱图显示，GRs的磷酸化位点在质量上没有显著差异，这与G2/M期间N-末端结构域的负电荷普遍增加一致。我们还表明，前面描述的从G1到S的GR激素结合能力的增加伴随着GR蛋白的平行增加。
Proliferating cells display striking cell cycle dependence in sensitivity to gene activation by glucocorticoids; they are sensitive in late gap 1/synthesis (G1/S) (late G1 and S phases) but resistant in gap 2/mitotic (G2/M), Here we describe large cell cycle-dependent variations in glucocorticoid receptor(GR) phosphorylation that accompany, and may account for, the changes in sensitivity, GRs are basally phosphorylated and undergo hyperphosphorylation after hormone-induced activation. Identified phosphorylated sites are all in the N-terminal domain. Several iie in a region required for full transactivating activity and reduction of nonspecific binding to DNA. Most are in consensus sequences for cell cycle-associated kinases, suggesting that such kinases phosphorylate GRs, We now show with WCL2 cells (Chinese hamster ovary cells with overexpressed GRs) that: 1) glucocorticoid treatment fails to hyperphosphorytate GRs in G2/M but doubles phosphorylation in S, more than seen with unsynchronized cells; and 2) basal GR phosphorylation is almost three times higher in G2/M than S, These results, along with earlier observations, implicate GR phosphorylation with mechanisms of glucocorticoid resistance in G2/M, Such mechanisms might underlie some forms of glucocorticoid resistance in inflammatory and lymphoproliferative diseases. HPLC phosphopeptide maps of GRs from S and G2/M reveal no significant qualitative differences in phosphorylated sites, consistent with a general increase during G2/M in negative charge of the N-terminal domain. We also show that the previously described increase in GR hormone-binding capacity from G1 to S is accompanied by a parallel increase in GR protein.