Machiyama Hiroaki, Hirata Hiroaki, Loh Xia Kun, Kanchi Madhu Mathi, Fujita Hideaki, Tan Song Hui, Kawauchi Keiko, Sawada Yasuhiro
Mechanobiology Institute, National University of Singapore, 117411 Singapore Department of Biological Sciences, National University of Singapore, 117411 Singapore.
Mechanobiology Institute, National University of Singapore, 117411 Singapore.
J Cell Sci. 2014 Aug 15;127(Pt 16):3440-50. doi: 10.1242/jcs.143438. Epub 2014 Jun 13.
Cell adhesion complexes provide platforms where cell-generated forces are transmitted to the extracellular matrix (ECM). Tyrosine phosphorylation of focal adhesion proteins is crucial for cells to communicate with the extracellular environment. However, the mechanisms that transmit actin cytoskeletal motion to the extracellular environment to drive cell migration are poorly understood. We find that the movement of p130Cas (Cas, also known as BCAR1), a mechanosensor at focal adhesions, correlates with actin retrograde flow and depends upon actomyosin contraction and phosphorylation of the Cas substrate domain (CasSD). This indicates that CasSD phosphorylation underpins the physical link between Cas and the actin cytoskeleton. Fluorescence recovery after photobleaching (FRAP) experiments reveal that CasSD phosphorylation, as opposed to the association of Cas with Src, facilitates Cas displacement from adhesion complexes in migrating cells. Furthermore, the stabilization of Src-Cas binding and inhibition of myosin II, both of which sustain CasSD phosphorylation but mitigate Cas displacement from adhesion sites, retard cell migration. These results indicate that Cas promotes cell migration by linking actomyosin contractions to the adhesion complexes through a dynamic interaction with Src as well as through the phosphorylation-dependent association with the actin cytoskeleton.
细胞黏附复合体提供了将细胞产生的力传递到细胞外基质（ECM）的平台。黏着斑蛋白的酪氨酸磷酸化对于细胞与细胞外环境的通讯至关重要。然而，将肌动蛋白细胞骨架运动传递到细胞外环境以驱动细胞迁移的机制仍知之甚少。我们发现，黏着斑处的机械传感器p130Cas（Cas，也称为BCAR1）的运动与肌动蛋白逆行流相关，并且依赖于肌动球蛋白收缩和Cas底物结构域（CasSD）的磷酸化。这表明CasSD磷酸化是Cas与肌动蛋白细胞骨架之间物理联系的基础。光漂白后荧光恢复（FRAP）实验表明，与Cas与Src的结合相反，CasSD磷酸化促进了Cas从迁移细胞中的黏附复合体上的位移。此外，Src-Cas结合的稳定和肌球蛋白II的抑制，这两者都维持CasSD磷酸化但减轻Cas从黏附位点的位移，会阻碍细胞迁移。这些结果表明，Cas通过与Src的动态相互作用以及与肌动蛋白细胞骨架的磷酸化依赖性结合，将肌动球蛋白收缩与黏附复合体联系起来，从而促进细胞迁移。
