Phosphorylation of glycogen synthase kinase-3 and stimulation of T-cell factor signaling following activation of EP2 and EP4 prostanoid receptors by prostaglandin E2
Phosphorylation of glycogen synthase kinase-3 and stimulation of T-cell factor signaling following activation of EP2 and EP4 prostanoid receptors by prostaglandin E2
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DOI：
10.1074/jbc.m109440200
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发表时间：
2002-01-25
影响因子：
4.8
通讯作者：
Regan, JW
中科院分区：
文献类型：
--
作者：
Fujino, H;West, KA;Regan, JW
最近我们已经表明，FP（前列腺素受体），一种与Gαq偶联的G蛋白偶联受体，可激活T细胞因子（Tcf）/淋巴增强因子（Lef）介导的转录激活（藤野，H.，和里根，J.W.（2001年）《生物化学杂志》276，12489 - 12492）。我们现在报道，与Gαs偶联的EP2和EP4前列腺素受体也能激活Tcf/Lef信号传导。通过使用一个对Tcf/Lef有响应的荧光素酶报告基因，在稳定转染了人EP2和EP4受体的HEK细胞中，用前列腺素E2（PGE2）处理1小时后，转录活性比基础水平提高了约10倍。报告基因活性的这种刺激伴随着糖原合成酶激酶 - 3（GSK - 3）和Akt激酶磷酸化的PGE2依赖性增加。H - 89，一种蛋白激酶A（PKA）抑制剂，在表达EP2和EP4的细胞中完全阻断了激动剂依赖性的GSK - 3磷酸化。然而，与在表达EP2的细胞中65%的抑制率相比，H - 89预处理在表达EP4的细胞中仅阻断了20%的PGE2刺激的Lef/Tcf报告基因活性。另一方面，渥曼青霉素，一种磷脂酰肌醇3 - 激酶抑制剂，具有相反的效果，并且与表达EP2的细胞相比，在表达EP4的细胞中更大程度地抑制了PGE2刺激的报告基因活性。这些发现表明，EP2受体对Tcf/Lef信号传导的激活主要通过PKA依赖性途径发生，而EP4受体主要通过磷脂酰肌醇3 - 激酶依赖性途径激活Tcf/Lef信号传导。这是EP2和EP4前列腺素受体在信号传导潜能方面存在根本差异的第一个迹象。
Recently we have shown that the FP, prostanoid receptor, a G-protein-coupled receptor that couples to Galpha(q), activates T-cell factor (Tcf)/Iymphoid enhancer factor (Lef)-mediated transcriptional activation (Fujino, H., and Regan, J. W. (2001) J. Biol. Chem. 276, 1248912492). We now report that the EP2 and EP4 prostanoid receptors, which couple to Galpha(s), also activate Tcf/Lef signaling. By using a Tcf/Lef-responsive luciferase reporter gene, transcriptional activity was stimulated similar to10-fold over basal by I h of treatment with prostaglandin E-2 (PGE(2)) in HEK cells that were stably transfected with the human EP2 and EP4 receptors. This stimulation of reporter gene activity was accompanied by a PGE(2)-dependent increase in the phosphorylation of both glycogen synthase kinase-3 (GSK-3) and Akt kinase. H-89, an inhibitor of protein kinase A (PKA), completely blocked the agonist-dependent phosphorylation of GSK-3 in both EP2- and EP4-expressing cells. However, H-89 pretreatment only blocked PGE(2)-stimulated Lef/Tef reporter gene activity by 20% in EP4-expressing cells compared with 65% inhibition in EP2-expressing cells. On the other hand wortmannin, an inhibitor of phosphatidylinositol 3-kinase, had the opposite effect and inhibited PGE(2)-stimulated reporter gene activity to a much greater extent in EP4-expressing cells as compared with EP2-expressing cells. These findings indicate that the activation of Tcf/Lef signaling by EP2 receptors occurs primarily through a PKA-dependent pathway, whereas EP4 receptors activate Tcf/Lef signaling mainly through a phosphatidylinositol 3-kinase-dependent pathway. This is the first indication of a fundamental difference in the signaling potential of EP2 and EP4 prostanoid receptors.