Arachidonic Acid Stimulates Cell Adhesion through a Novel p38 MAPK-RhoA Signaling Pathway That Involves Heat Shock Protein 27
Arachidonic Acid Stimulates Cell Adhesion through a Novel p38 MAPK-RhoA Signaling Pathway That Involves Heat Shock Protein 27
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DOI：
10.1074/jbc.m109.020271
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发表时间：
2009-07-31
影响因子：
4.8
通讯作者：
Roberts, John D.
中科院分区：
文献类型：
--
作者：
Garcia, Melissa C.;Ray, Denise M.;Roberts, John D.
Rho GTP酶是细胞信号转导途径的关键组分。在人类癌症中已经观察到这些蛋白质的过度活性和过度表达，并且这些蛋白质被认为是转移的重要因素。我们以前表明，饮食n-6脂肪酸增加癌细胞粘附细胞外基质蛋白，如IV型胶原蛋白。在这里，我们报告说，在MDA-MB-435人黑色素瘤细胞，花生四烯酸激活RhoA，和抑制RhoA信号与C3外切酶或显性负Rho阻断花生四烯酸诱导的细胞粘附。用小分子抑制剂或ROCK II特异性小干扰RNA（siRNA）抑制Rho激酶（ROCK）阻断脂肪酸诱导的粘附。然而，与其他系统不同的是，ROCK的抑制并不能阻断p38丝裂原活化蛋白激酶（MAPK）的激活;相反，Rho的激活依赖于p38 MAPK活性和热休克蛋白27（HSP 27）的存在，后者在花生四烯酸处理后在p38下游磷酸化。在脂肪酸处理的细胞中，HSP 27与p115 RhoGEF相关，当p38被抑制时，这种关联被阻断。此外，HSP 27的siRNA敲低阻断了脂肪酸刺激的Rho活性。显性负性p115-RhoGEF或p115 RhoGEF特异性siRNA的表达抑制了RhoA活化和对IV型胶原的粘附，而组成型活性p115 RhoGEF恢复了p38 MAPK被抑制的细胞中花生四烯酸的刺激。这些数据表明，n-6膳食脂肪酸刺激一组相互作用，通过RhoA和ROCK II通过HSP 27和p115 RhoGEF的p38 MAPK依赖性协会调节细胞粘附。
Rho GTPases are critical components of cellular signal transduction pathways. Both hyperactivity and overexpression of these proteins have been observed in human cancers and have been implicated as important factors in metastasis. We previously showed that dietary n-6 fatty acids increase cancer cell adhesion to extracellular matrix proteins, such as type IV collagen. Here we report that in MDA-MB-435 human melanoma cells, arachidonic acid activates RhoA, and inhibition of RhoA signaling with either C3 exoenzyme or dominant negative Rho blocked arachidonic acid-induced cell adhesion. Inhibition of the Rho kinase (ROCK) with either small molecule inhibitors or ROCK II-specific small interfering RNA (siRNA) blocked the fatty acid-induced adhesion. However, unlike other systems, inhibition of ROCK did not block the activation of p38 mitogen-activated protein kinase (MAPK); instead, Rho activation depended on p38 MAPK activity and the presence of heat shock protein 27 (HSP27), which is phosphorylated downstream of p38 after arachidonic acid treatment. HSP27 associated with p115RhoGEF in fatty acid-treated cells, and this association was blocked when p38 was inhibited. Furthermore, siRNA knockdown of HSP27 blocked the fatty acid-stimulated Rho activity. Expression of dominant negative p115-RhoGEF or p115RhoGEF-specific siRNA inhibited both RhoA activation and adhesion on type IV collagen, whereas a constitutively active p115RhoGEF restored the arachidonic acid stimulation in cells in which the p38 MAPK had been inhibited. These data suggest that n-6 dietary fatty acids stimulate a set of interactions that regulates cell adhesion through RhoA and ROCK II via a p38 MAPK-dependent association of HSP27 and p115RhoGEF.