βγ subunits of Gi/o suppress EGF-induced ERK5 phosphorylation, whereas ERK1/2 phosphorylation is enhanced
βγ subunits of Gi/o suppress EGF-induced ERK5 phosphorylation, whereas ERK1/2 phosphorylation is enhanced
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DOI：
10.1016/j.cellsig.2008.02.016
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发表时间：
2008-07-01
影响因子：
4.8
通讯作者：
Nakahata, Norimichi
中科院分区：
文献类型：
--
作者：
Obara, Yutaro;Okano, Yumiko;Nakahata, Norimichi
细胞外信号调节激酶（extracellular signal-regulated kinases，ERK）在细胞增殖、分化和基因表达中起着重要的生理作用。ERK 5的大小是ERK 1/2的两倍，氨基端的一半含有与ERK 1/2和TEY激活基序同源的激酶结构域，而羧基端的一半是独特的。在这项研究中，我们研究了G蛋白偶联受体（GPCRs）和受体酪氨酸激酶之间的串扰机制，重点是ERK 1/2和5。用百日咳毒素（PTX）预处理大鼠嗜铬细胞瘤细胞（PC 12），特异性增强表皮生长因子（EGF）诱导的ERK 5磷酸化。此外，溶血磷脂酸（LPA）以LPA（1）受体和G（i/o）依赖的方式减弱EGF诱导的ERK 5磷酸化。另一方面，LPA单独通过G β γ亚基和Ras激活ERK 1/2，并在晚期时间点增强EGF诱导的ERK 1/2磷酸化。这些结果表明G（i/o）负性调节ERK 5，而正性调节ERK 1/2。EGF处理后，LPA不影响cAMP水平，促进cAMP产生的试剂如毛喉素和霍乱毒素也减弱EGF诱导的ERK 5磷酸化，表明LPA通过G（i/o）对ERK 5抑制的抑制作用不是由于G（alpha i/o）抑制腺苷酸环化酶。但在稳定过表达GRK 2的PC 12细胞中，LPA对ERK 5的抑制作用被消除，且G β 1和γ 2亚基的过表达也抑制EGF对ERK 5的磷酸化。在LPA的作用下，G β γ亚基与EGF受体以时间依赖性的方式相互作用。这些结果有力地表明，LPA通过G β γ亚基负调控EGF诱导的ERK 5磷酸化。(c)2008年爱思唯尔公司All rights reserved.
Extracellular signal-regulated kinases (ERKs) play important physiological roles in proliferation, differentiation and gene expression. ERK5 is twice the size of ERK1/2, the amino-terminal half contains the kinase domain that shares the homology with ERK1/2 and TEY activation motif, whereas the carboxy-terminal half is unique. In this study, we examined the cross-talk mechanism between G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases, focusing on ERK1/2 and 5. The pretreatment of rat pheochromocytoma cells (PC12) with pertussis toxin (PTX) specifically enhanced epidermal growth factor (EGF)-induced ERK5 phosphorylation. In addition, lysophosphatidic acid (LPA) attenuated the EGF-induced ERK5 phosphorylation in LPA(1) receptor- and G(i/o) -dependent manners. On the other hand, LPA alone activated ERK1/2 via G beta gamma subunits and Ras and potentiated EGF-induced ERK1/2 phosphorylation at late time points. These results suggest G(i/o) negatively regulates ERK5, while it positively regulates ERK1/2. LPA did not affect cAMP levels after EGF treatment, and the reagents promoting cAMP production such as forskolin and cholera toxin also attenuated the EGF-induced ERK5 phosphorylation, indicating that the inhibitory effect of LPA on ERK5 inhibition via G(i/o) is not due to inhibition of adenylyl cyclase by G(alpha i/o). However, the inhibitory effect of LPA on ERK5 was abolished in PC12 cells stably overexpressing C-terminus of GPCR kinase2 (GRK2), and overexpression of G beta(1) and gamma(2) subunits also suppressed ERK5 phosphorylation by EGF. In response to LPA, G beta gamma subunits interacted with EGF receptor in a time-dependent manner. These results strongly suggest that LPA negatively regulates the EGF-induced ERK5 phosphorylation through G beta gamma subunits. (c) 2008 Elsevier Inc. All rights reserved.