Center for Cardiovascular Sciences, Albany Medical College, Albany, New York.
Am J Physiol Cell Physiol. 2014 Apr 15;306(8):C753-61. doi: 10.1152/ajpcell.00327.2013. Epub 2014 Jan 29.
c-Abl is a nonreceptor protein tyrosine kinase that has a role in regulating smooth muscle cell proliferation and contraction. The role of c-Abl in smooth muscle cell migration has not been investigated. In the present study, c-Abl was found in the leading edge of smooth muscle cells. Knockdown of c-Abl by RNA interference attenuated smooth muscle cell motility as evidenced by time-lapse microscopy. Furthermore, the actin-associated proteins cortactin and profilin-1 (Pfn-1) have been implicated in cell migration. In this study, cell adhesion induced cortactin phosphorylation at Tyr-421, an indication of cortactin activation. Phospho-cortactin and Pfn-1 were also found in the cell edge. Pfn-1 directly interacted with cortactin in vitro. Silencing of c-Abl attenuated adhesion-induced cortactin phosphorylation and Pfn-1 localization in the cell edge. To assess the role of cortactin/Pfn-1 coupling, we developed a cell-permeable peptide. Treatment with the peptide inhibited the interaction of cortactin with Pfn-1 without affecting cortactin phosphorylation. Moreover, treatment with the peptide impaired the recruitment of Pfn-1 to the leading edge and cell migration. Finally, β1-integrin was required for the recruitment of c-Abl to the cell edge. Inhibition of actin dynamics impaired the spatial distribution of c-Abl. These results suggest that β1-integrin may recruit c-Abl to the leading cell edge, which may regulate cortactin phosphorylation in response to cell adhesion. Phosphorylated cortactin may facilitate the recruitment of Pfn-1 to the cell edge, which promotes localized actin polymerization, leading edge formation, and cell movement. Conversely, actin dynamics may strengthen the recruitment of c-Abl to the leading edge.
c-Abl 是一种非受体蛋白酪氨酸激酶，在调节平滑肌细胞增殖和收缩方面发挥作用。c-Abl 在平滑肌细胞迁移中的作用尚未得到研究。在本研究中，c-Abl 存在于平滑肌细胞的前缘。RNA 干扰敲低 c-Abl 可减弱平滑肌细胞的迁移能力，这可通过延时显微镜观察到。此外，肌动蛋白相关蛋白 cortactin 和 Profilin-1（Pfn-1）已被牵连到细胞迁移中。在这项研究中，细胞黏附诱导 cortactin 在 Tyr-421 发生磷酸化，这表明 cortactin 被激活。磷酸化 cortactin 和 Pfn-1 也存在于细胞膜边缘。Pfn-1 可在体外与 cortactin 直接相互作用。c-Abl 沉默减弱了黏附诱导的 cortactin 磷酸化和 Pfn-1 在细胞膜边缘的定位。为了评估 cortactin/Pfn-1 偶联的作用，我们开发了一种细胞通透性肽。该肽处理抑制了 cortactin 与 Pfn-1 的相互作用，而不影响 cortactin 的磷酸化。此外，该肽处理损害了 Pfn-1 向细胞膜前缘的募集和细胞迁移。最后，β1-整合素是 c-Abl 募集到细胞膜前缘所必需的。肌动蛋白动力学的抑制损害了 c-Abl 的空间分布。这些结果表明，β1-整合素可能将 c-Abl 募集到细胞膜前缘，这可能调节细胞黏附后 cortactin 的磷酸化。磷酸化 cortactin 可能促进 Pfn-1 募集到细胞膜边缘，从而促进局部肌动蛋白聚合、前缘形成和细胞运动。相反，肌动蛋白动力学可能增强 c-Abl 向细胞膜前缘的募集。
