μ-opioid receptor-mediated ERK activation involves calmodulin-dependent epidermal growth factor receptor transactivation
μ-opioid receptor-mediated ERK activation involves calmodulin-dependent epidermal growth factor receptor transactivation
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DOI：
10.1074/jbc.m101535200
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发表时间：
2001-09-07
影响因子：
4.8
通讯作者：
Coscia, CJ
中科院分区：
文献类型：
--
作者：
Belcheva, MM;Szùcs, M;Coscia, CJ
G蛋白偶联受体对MAPK亚型ERK的磷酸化涉及多条信号通路。其中一个途径需要生长因子受体的反式激活，然后是ERK的激活。这项研究表明，HEK293细胞中表达的mU-阿片受体(MOR)也使用了类似的信号通路，并涉及钙调蛋白(CaM)。刺激MOR可导致表皮生长因子受体(EGFR)和ERK的磷酸化。使用EGFR酪氨酸激酶和膜金属蛋白酶抑制剂获得的数据支持EGFR激活的中间作用，包括释放内源性膜结合的表皮生长因子。以前的研究已经证明了CaM在阿片信号转导中的作用，这是基于CaM与MOR的直接结合。为了测试CaM是否参与了MOR对EGFR的反式激活和ERK的磷酸化，我们比较了野生型MOR和突变体K273A MOR，后者与CaM结合得很差，但通常与G蛋白偶联。[D-Ala(2)，MePhe(4)，Gly-ol(5)]脑啡肽(10-100 nM)刺激K273A MOR可显著降低ERK的磷酸化。此外，野生型MOR刺激EGFR Tyr的磷酸化是K273A MOR的3倍以上，表明CaM-MOR直接相互作用在反式激活过程中起着关键作用。CaM和蛋白激酶C的抑制剂也减弱了脑啡肽诱导的野生型(但不是突变型)MOR表达细胞中的EGFR反式激活。这一新的EGFR反式激活途径可能被其他与CaM相互作用的G蛋白偶联受体所共享。
Phosphorylation of the MAPK isoform ERK by G protein-coupled receptors involves multiple signaling pathways. One of these pathways entails growth factor receptor transactivation followed by ERK activation. This study demonstrates that a similar signaling pathway is used by the mu -opioid receptor (MOR) expressed in HEK293 cells and involves calmodulin (CaM). Stimulation of MOR resulted in both epidermal growth factor receptor (EGFR) and ERK phosphorylation. Data obtained with inhibitors of EGFR Tyr kinase and membrane metalloproteases support an intermediate role of EGFR activation, involving release of endogenous membrane-bound epidermal growth factor. Previous studies had demonstrated a role for CaM in opioid signaling based on direct CaM binding to MOR. To test whether CaM contributes to EGFR transactivation and ERK phosphorylation by MOR, we compared wild-type MOR with mutant K273A MOR, which binds CaM poorly, but couples normally to G proteins. Stimulation of K273A MOR with [D-Ala(2), MePhe(4), Gly-ol(5)]enkephalin (10-100 nM) resulted in significantly reduced ERK phosphorylation. Furthermore, wild-type MOR stimulated EGFR Tyr phosphorylation 3-fold more than K273A MOR, indicating that direct CaM-MOR interaction plays a key role in the transactivation process. Inhibitors of CaM and protein kinase C also attenuated [D-Ala(2), MePhe(4), Glyol(5)]enkephalin-induced EGFR transactivation in wildtype (but not mutant) MOR-expressing cells. This novel pathway of EGFR transactivation may be shared by other G protein-coupled receptors shown to interact with CaM.