Mechanisms of p130Cas-mediated mechano-sensing in cells

贴壁细胞在机械压力下表现出广泛的反应，包括机械行为和基因表达模式的大规模变化。这在一定程度上是通过激活粘着斑蛋白p130Cas，通过力诱导的构象变化，随后导致下游通路的激活，如细胞外信号调节激酶(ERK1/2)的磷酸化。我们最近已经证明，p130Cas上的磷酸化位点Y12调节与纽蛋白的结合，纽蛋白是焦点黏附复合体中一种重要的机械偶联蛋白。初步数据显示，Y12的磷酸化或突变与模拟磷酸化的谷氨酸Y12E抑制p130Cas与纽蛋白的结合，导致局部粘连中p130Cas定位的下降，以及拉伸诱导的p130Cas激活和下游ERK1/2信号的减少。这些观察结果表明，纽蛋白是p130Cas介导的细胞机械信号转导途径的重要调节器。该项目的中心目标是检验纽蛋白对p130Cas整合到焦点黏附复合体和向p130Cas分子传递力至关重要的假说。

Adherent cells, when mechanically stressed, show a wide range of responses including large-scale changes in their mechanical behavior and gene expression pattern. This is in part facilitated by activating the focal adhesion protein p130Cas through force-induced conformational changes that subsequently lead to activation of downstream pathways such as extracellular-signal-regulated kinase (ERK1/2) phosphorylation. We have recently demonstrated that the phosphorylation site Y12 on p130Cas modulates the binding with vinculin, which is a prominent mechano-coupling protein in the focal adhesion complex. Preliminary data show that phosphorylation of Y12 or mutation with phospho-mimicking glutamate Y12E suppresses the binding of p130Cas to vinculin, leads to a decline of p130Cas localization in focal adhesions, and to a reduction of stretch-induced p130Cas activation and downstream ERK1/2 signaling. These observations demonstrate that vinculin is an important modulator of the p130Cas-mediated mechano-transduction pathway in cells. The central aim of this project is to test the hypothesis that vinculin is critical for p130Cas incorporation into the focal adhesion complex and for transmitting forces to the p130Cas molecule.