EphrinA1 inactivates integrin-mediated vascular smooth muscle cell spreading via the Rac/PAK pathway
EphrinA1 inactivates integrin-mediated vascular smooth muscle cell spreading via the Rac/PAK pathway
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DOI：
10.1242/jcs.00308
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发表时间：
2003-04-01
影响因子：
4
通讯作者：
Pouysségur, J
中科院分区：
文献类型：
--
作者：
Deroanne, C;Vouret-Craviari, V;Pouysségur, J
Eph受体酪氨酸激酶和ephrin配体之间的相互作用传递调节轴突寻路、心血管系统发育以及神经元和非神经元细胞迁移和扩散的短程信号。其中一些作用被认为是由肌动蛋白动力学的改变介导的。小Rho GTdR家族的成员引起肌动蛋白结构的各种影响，并可能参与Eph受体诱导的肌动蛋白调节。EphrinA 1被认为有助于血管生成，因为它在新血管形成部位强烈表达。此外，血管生成因子诱导ephrinA 1在内皮细胞中的表达。在这项研究中，使用大鼠血管平滑肌细胞（VSMCs），我们调查的贡献小Rho GTPases ephrinA 1诱导的整合素失活。EphrinA 1没有显着影响VSMCs对纯化层粘连蛋白或纤连蛋白的早期粘附，但强烈损害细胞铺展。Rho激酶抑制剂Y-27632部分逆转了ephrinA 1的作用，表明Rho参与了该模型。然而，抑制RhoA合成与短干扰（si）RNA有适度的影响，表明RhoA在ephrinA 1介导的抑制VSMCs的扩散中起着有限的作用。ephrinA 1介导的形态学改变与Rac 1和p21激活的激酶I（PAK 1）活性的抑制相关，并被组成型活性Rac突变体的表达所拮抗。此外，用siRNA抑制Rac 1合成放大了ephrinA 1诱导的扩散抑制。最后，鞘氨醇-1-磷酸（SO），一种脂质介质，已知抑制Rac激活VSMCs放大ephrinA 1的效果。总之，我们的研究结果强调了Rac/PAK通路在ephrinA 1介导的扩散抑制中的作用。以这种方式，ephrinA 1，单独或与SO协同，可以参与血管不稳定，血管生成的先决条件。
Interactions between the Eph receptor tyrosine kinase and ephrin ligands transiduce short-range signals regulating axon pathfinding, development of the cardiovascular system, as well as migration and spreading of neuronal and non-neuronal cells. Some of these effects are believed to be mediated by alterations in actin dynamics. The members of the small Rho GTPase family elicit various effects on actin structures and are probably involved in Eph receptor-induced actin modulation. EphrinA1 is proposed to contribute to angiogenesis as it is strongly expressed at sites of neovascularization. Moreover, angiogenic factors induce the expression of ephrinA1 in endothelial cells. In this study, using rat vascular smooth muscle cells (VSMCs), we investigated the contribution of the small Rho GTPases in ephrinA1-induced integrin inactivation. EphrinA1 did not significantly affect early adhesion of VSMCs on purified laminin or fibronectin, but strongly impaired cell spreading. The Rho kinase inhibitor Y-27632 partly reversed the ephrinA1 effect, suggesting involvement of Rho in this model. However, inhibition of RhoA synthesis with short interfering (si)RNA had a modest effect, suggesting that RhoA plays a limited role in ephrinA1-mediated inhibition of spreading in VSMCs. The ephrinA1-mediated morphological alterations correlated with inhibition of Rac1 and p21-activated kinase I (PAK1) activity, and were antagonized by the expression of a constitutively active Rac mutant. Moreover, repression of Rac1 synthesis with siRNA amplifies the ephrinA1-induced inhibition of spreading. Finally, sphingosine-1-phosphate (SO), a lipid mediator known to inhibit Rac activation in VSMCs amplifies the ephrinA1 effect. In conclusion, our results emphasize the role of the Rac/PAK pathway in ephrinA1-mediated inhibition of spreading. In this way, ephrinA1, alone or in synergy with SO, can participate in blood vessel destabilization, a prerequisite for angiogenesis.