Gα12/13- and rho-dependent activation of phospholipase C-ε by lysophosphatidic acid and thrombin receptors
Gα12/13- and rho-dependent activation of phospholipase C-ε by lysophosphatidic acid and thrombin receptors
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DOI：
10.1124/mol.105.017921
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发表时间：
2006-06-01
影响因子：
3.6
通讯作者：
Harden, T. Kendall
中科院分区：
文献类型：
--
作者：
Hains, Melinda D.;Wing, Michele R.;Harden, T. Kendall
由于磷脂酶C-epsilon （PLC-epsilon）被G α(12/13)和Rho家族gtpase激活，我们研究了这些G蛋白是否有助于在某些G蛋白偶联受体激活后在COS-7细胞中观察到的肌醇脂水解增加。内源性溶血磷脂酸（LPA）或凝血酶受体对肌醇脂质水解的刺激作用被PLC-epsilon的表达显著增强。LPA(1)或PAR1受体的表达分别在LPA或SFLLRN的作用下增加了肌醇磷酸的产生，这些激动剂刺激的反应被PLC-epsilon的共同表达显著增强。LPA(1)和PAR1受体介导的PLC-epsilon的激活均可通过G α的gtpase激活蛋白p115RhoGEF的G蛋白信号（RGS）调节域的共表达而抑制（12/13），但不能通过抑制G α (q)信号的GRK2的RGS结构域的表达而抑制。相比之下，G(q)偶联M1毒蕈碱或P2Y(2)嘌呤能受体的激活既不因与PLC-epsilon共表达而增强，也不因p115RhoGEF的RGS结构域而受到抑制，但却因GRK2的RGS结构域的表达而被阻断。在没有PLC-epsilon的情况下，Rho抑制剂C3肉毒毒素的表达不影响LPA-或sfllrn刺激的肌醇脂质水解，但完全阻止了PLC-epsilon依赖性肌醇磷酸积累的增加。同样，C3毒素阻断了LPA(1)、LPA(2)、LPA(3)或PAR1受体的plc -epsilon依赖性刺激作用，但对M1或P2Y(2)受体的激动剂促进的肌醇磷酸反应没有影响。此外，通过激活表皮生长因子受体，plc -epsilon依赖性刺激肌醇磷酸积累，包括Ras介导的磷脂酶激活，而不是rho介导的磷脂酶激活，不受C3毒素影响。这些研究表明，特异性LPA和凝血酶受体通过激活G α(12/13)和Rho来促进肌醇脂质信号传导。
Because phospholipase C epsilon (PLC-epsilon) is activated by G alpha(12/13) and Rho family GTPases, we investigated whether these G proteins contribute to the increased inositol lipid hydrolysis observed in COS-7 cells after activation of certain G protein-coupled receptors. Stimulation of inositol lipid hydrolysis by endogenous lysophosphatidic acid (LPA) or thrombin receptors was markedly enhanced by the expression of PLC-epsilon. Expression of the LPA(1) or PAR1 receptor increased inositol phosphate production in response to LPA or SFLLRN, respectively, and these agonist-stimulated responses were markedly enhanced by coexpression of PLC-epsilon. Both LPA(1) and PAR1 receptor-mediated activation of PLC-epsilon was inhibited by coexpression of the regulator of G protein signaling (RGS) domain of p115RhoGEF, a GTPase-activating protein for G alpha(12/13) but not by expression of the RGS domain of GRK2, which inhibits G alpha(q) signaling. In contrast, activation of the G(q)-coupled M1 muscarinic or P2Y(2) purinergic receptor was neither enhanced by coexpression with PLC-epsilon nor inhibited by the RGS domain of p115RhoGEF but was blocked by expression of the RGS domain of GRK2. Expression of the Rho inhibitor C3 botulinum toxin did not affect LPA- or SFLLRN-stimulated inositol lipid hydrolysis in the absence of PLC-epsilon but completely prevented the PLC-epsilon-dependent increase in inositol phosphate accumulation. Likewise, C3 toxin blocked the PLC-epsilon-dependent stimulatory effects of the LPA(1), LPA(2), LPA(3), or PAR1 receptor but had no effect on the agonist-promoted inositol phosphate response of the M1 or P2Y(2) receptor. Moreover, PLC-epsilon-dependent stimulation of inositol phosphate accumulation by activation of the epidermal growth factor receptor, which involves Ras- but not Rho-mediated activation of the phospholipase, was unaffected by C3 toxin. These studies illustrate that specific LPA and thrombin receptors promote inositol lipid signaling via activation of G alpha(12/13) and Rho.