The distribution of vinculin to lipid rafts plays an important role in sensing stiffness of extracellular matrix

Extracellular matrix (ECM) stiffness regulates cell differentiation, survival, and migration. Our previous study has shown that the interaction of the focal adhesion protein vinculin with vinexin α plays a critical role in sensing ECM stiffness and regulating stiffness-dependent cell migration. However, the mechanism how vinculin–vinexin α interaction affects stiffness-dependent cell migration is unclear. Lipid rafts are membrane microdomains that are known to affect ECM-induced signals and cell behaviors. Here, we show that vinculin and vinexin α can localize to lipid rafts. Cell-ECM adhesion, intracellular tension, and a rigid ECM promote vinculin distribution to lipid rafts. The disruption of lipid rafts with Methyl-β-cyclodextrin impaired the ECM stiffness-mediated regulation of vinculin behavior and rapid cell migration on rigid ECM. These results indicate that lipid rafts play an important role in ECM-stiffness regulation of cell migration via vinculin. Vinculin is in non-raft on soft ECM. Rigid ECM promotes vinculin binding to vinexin α and PIP2, leading to distribution to raft and enhanced migration

细胞外基质（Extracellular matrix, ECM）的刚度可调控细胞的分化、存活与迁移。本课题组前期研究证实，黏着斑蛋白纽蛋白（vinculin）与α-纽带蛋白（vinexin α）的相互作用，在感知ECM刚度以及调控刚度依赖性细胞迁移的过程中发挥关键作用。然而，纽蛋白与α-纽带蛋白的相互作用如何影响刚度依赖性细胞迁移的具体机制仍未阐明。脂筏（lipid rafts）是一类已知可调控ECM诱导信号通路与细胞行为的膜微区结构。本研究发现，纽蛋白与α-纽带蛋白均可定位于脂筏。细胞-ECM黏附、细胞内张力以及刚性ECM可促进纽蛋白向脂筏区域的分布。采用甲基-β-环糊精（Methyl-β-cyclodextrin）破坏脂筏结构，会削弱ECM刚度介导的纽蛋白行为调控，以及细胞在刚性ECM表面的快速迁移能力。上述结果表明，脂筏可通过纽蛋白参与ECM刚度对细胞迁移的调控过程。在软ECM环境中，纽蛋白定位于非脂筏区域；而刚性ECM可促进纽蛋白与α-纽带蛋白及磷脂酰肌醇二磷酸（PIP2）结合，进而使其向脂筏区域募集并增强细胞迁移能力。