Diacylglycerol Kinase ζ Regulates Actin Cytoskeleton Reorganization through Dissociation of Rac1 from RhoGDI
Diacylglycerol Kinase ζ Regulates Actin Cytoskeleton Reorganization through Dissociation of Rac1 from RhoGDI
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DOI：
10.1091/mbc.e07-12-1248
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发表时间：
2009-04-01
影响因子：
3.3
通讯作者：
Gee, Stephen H.
中科院分区：
文献类型：
--
作者：
Abramovici, Hanan;Mojtabaie, Parmiss;Gee, Stephen H.
Rac1 GTPase信号的激活是由效应物p21活化激酶1 （PAK1）磷酸化和释放RhoGDI刺激的，但尚不清楚是什么启动了这种调节Rac活性的潜在前馈机制。磷脂酸（PA）由脂质第二信使二酰基甘油（DAG）通过DAG激酶（DGKs）的作用产生，已知可激活PAK1。在这里，我们研究了DGK zeta产生的PA是否启动RhoGDI释放和Rac1激活。在DGK中，齐塔缺陷成纤维细胞PAK1磷酸化和Rac1- rhogdi解离减弱，导致血小板源性生长因子刺激后Rac1活化减少。细胞在rac1调控的行为中存在缺陷，包括板足形成、膜褶皱、迁移和扩散。野生型DGK zeta，但不是激酶死亡突变体，或添加外源PA可恢复Rac激活。DGK zeta与PAK1和RhoGDI稳定相关，表明这些蛋白形成一个复合物，作为rac1选择性RhoGDI解离因子。这些结果定义了一条将二酰基甘油、DGK zeta和PA与Rac1激活联系起来的途径：DGK zeta产生的PA激活PAK1，使RhoGDI与Rac1分离，导致肌动蛋白动力学的变化，促进细胞运动所必需的变化。
Activation of Rac1 GTPase signaling is stimulated by phosphorylation and release of RhoGDI by the effector p21-activated kinase 1 (PAK1), but it is unclear what initiates this potential feed-forward mechanism for regulation of Rac activity. Phosphatidic acid (PA), which is produced from the lipid second messenger diacylglycerol (DAG) by the action of DAG kinases (DGKs), is known to activate PAK1. Here, we investigated whether PA produced by DGK zeta initiates RhoGDI release and Rac1 activation. In DGK zeta-deficient fibroblasts PAK1 phosphorylation and Rac1-RhoGDI dissociation were attenuated, leading to reduced Rac1 activation after platelet-derived growth factor stimulation. The cells were defective in Rac1-regulated behaviors, including lamellipodia formation, membrane ruffling, migration, and spreading. Wild-type DGK zeta, but not a kinase-dead mutant, or addition of exogenous PA rescued Rac activation. DGK zeta stably associated with PAK1 and RhoGDI, suggesting these proteins form a complex that functions as a Rac1-selective RhoGDI dissociation factor. These results define a pathway that links diacylglycerol, DGK zeta, and PA to the activation of Rac1: the PA generated by DGK zeta activates PAK1, which dissociates RhoGDI from Rac1 leading to changes in actin dynamics that facilitate the changes necessary for cell motility.