Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
Nat Commun. 2018 Oct 26;9(1):4465. doi: 10.1038/s41467-018-06906-7.
Dynamic communication between integrin-containing complexes (focal adhesions, FAs) and actin filaments is critical for regulating cell adhesion. Pseudokinase ILK plays a key role in this process but the underlying mechanism remains highly elusive. Here we show that by recruiting FA adaptors PINCH and Parvin into a heterotrimeric complex (IPP), ILK triggers F-actin filament bundling - a process known to generate force/mechanical signal to promote cytoskeleton reassembly and dynamic cell adhesion. Structural, biochemical, and functional analyses revealed that the F-actin bundling is orchestrated by two previously unrecognized WASP-Homology-2 actin binding motifs within IPP, one from PINCH and the other from Parvin. Strikingly, this process is also sensitized to Mg-ATP bound to the pseudoactive site of ILK and its dysregulation severely impairs stress fibers formation, cell spreading, and migration. These data identify a crucial mechanism for ILK, highlighting its uniqueness as a pseudokinase to transduce non-catalytic signal and regulate cell adhesion.
整合素包含复合物（黏着斑，FA）与肌动蛋白丝之间的动态通讯对于调节细胞黏附至关重要。假激酶 ILK 在这个过程中起着关键作用，但潜在的机制仍然非常难以捉摸。在这里，我们表明，通过将 FA 衔接蛋白 PINCH 和 Parvin 招募到三聚体复合物（IPP）中，ILK 引发 F-肌动蛋白丝束状化——这一过程已知会产生力/机械信号，以促进细胞骨架重组和动态细胞黏附。结构、生化和功能分析表明，IPP 中的两个以前未被识别的 Wiskott-Aldrich 综合征蛋白同源物 2（WASP-Homology-2）肌动蛋白结合基序协调 F-肌动蛋白束状化，一个来自 PINCH，另一个来自 Parvin。引人注目的是，这个过程也对结合在 ILK 假活性位点上的 Mg-ATP 敏感，其失调严重损害了应力纤维的形成、细胞铺展和迁移。这些数据确定了 ILK 的一个关键机制，突出了其作为一种非催化信号转导和调节细胞黏附的假激酶的独特性。
