Integrin adhesion and force coupling are independently regulated by localized PtdIns(4,5)2 synthesis

The 90-kDa isoform of the lipid kinase PIP kinase Type I c (PIPKI gamma) localizes to focal adhesions (FAs), where it provides a local source of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P-2). Although PtdIns(4,5) P2 regulates the function of several FA-associated molecules, the role of the FA-specific pool of PtdIns(4,5)P-2 is not known. We report that the genetic ablation of PIPKI gamma specifically from FAs results in defective integrin-mediated adhesion and force coupling. Adhesion defects in cells deficient in FA-PtdIns(4,5)P-2 synthesis are corrected within minutes while integrin-actin force coupling remains defective over a longer period. Talin and vinculin, but not kindlin, are less efficiently recruited to new adhesions in these cells. These data demonstrate that the specific depletion of PtdIns(4,5) P2 from FAs temporally separates integrin-ligand binding from integrin-actin force coupling by regulating talin and vinculin recruitment. Furthermore, it suggests that force coupling relies heavily on locally generated PtdIns(4,5) P2 rather than bulk membrane PtdIns(4,5) P2. The EMBO Journal (2011) 30, 4539-4553. doi: 10.1038/emboj.2011.332; Published online 16 September 2011 Subject Categories: membranes & transport; cell & tissue architecture