Laboratory for Toxicopathology, Institute of Pathology, Rikshospitalet University Hospital, University of Oslo, Oslo, Norway.
J Cell Physiol. 2011 Sep;226(9):2267-78. doi: 10.1002/jcp.22563.
Reactive oxygen species (ROS) function as signaling molecules mainly by reversible oxidation of redox-sensitive target proteins. ROS can be produced in response to integrin ligation and growth factor stimulation through Rac1 and its effector protein NADPH oxidase. One of the central roles of Rac1-NADPH oxidase is actin cytoskeletal rearrangement, which is essential for cell spreading and migration. Another important regulator of cell spread is focal adhesion kinase (FAK), a coordinator of integrin and growth factor signaling. Here, we propose a novel role for NADPH oxidase as a modulator of the FAK autophosphorylation site. We found that Rac1-NADPH oxidase enhanced the phosphorylation of FAK at Y397. This site regulates FAK's ability to act as a scaffold for EGF-mediated signaling, including activation of ERK. Accordingly, we found that EGF-induced activation of FAK at Y925, the following activation of ERK, and phosphorylation of FAK at the ERK-regulated S910-site depended upon NADPH oxidase. Furthermore, the inhibition of NADPH oxidase caused excessive focal adhesions, which is in accordance with ERK and FAK being modulators of focal adhesion dissociation. Our data suggest that Rac1 through NADPH oxidase is part of the signaling pathway constituted by FAK, Rac1, and ERK that regulates focal adhesion disassembly during cell spreading.
活性氧（ROS）主要通过氧化还原敏感靶蛋白的可逆氧化来作为信号分子发挥作用。ROS 可以通过 Rac1 及其效应蛋白 NADPH 氧化酶对整合素连接和生长因子刺激做出反应而产生。Rac1-NADPH 氧化酶的一个核心作用是肌动蛋白细胞骨架的重排，这对于细胞铺展和迁移是必不可少的。细胞铺展的另一个重要调节因子是粘着斑激酶（FAK），它是整合素和生长因子信号的协调者。在这里，我们提出 NADPH 氧化酶作为 FAK 自身磷酸化位点调节剂的新作用。我们发现 Rac1-NADPH 氧化酶增强了 FAK 在 Y397 处的磷酸化。该位点调节 FAK 作为 EGF 介导的信号传导，包括 ERK 激活的支架的能力。因此，我们发现 EGF 诱导的 FAK 在 Y925 处的激活、随后的 ERK 激活以及 ERK 调节的 S910 位点的 FAK 磷酸化取决于 NADPH 氧化酶。此外，NADPH 氧化酶的抑制导致了过多的焦点粘连，这与 ERK 和 FAK 作为焦点粘连解离的调节剂一致。我们的数据表明，Rac1 通过 NADPH 氧化酶是由 FAK、Rac1 和 ERK 构成的信号通路的一部分，该信号通路调节细胞铺展过程中粘着斑的解体。
