CaMK‐II promotes focal adhesion turnover and cell motility by inducing tyrosine dephosphorylation of FAK and paxillin

Abstract

Transient elevations in Ca 2+ have previously been shown to promote focal adhesion disassembly and cell motility through an unknown mechanism. In this study, evidence is provided to show that CaMK-II, a Ca 2+ /calmodulin dependent protein kinase, influences fibroblast adhesion and motility. TIRF microscopy reveals a dynamic population of CaMK-II at the cell surface in migrating cells. Inhibition of CaMK-II with two mechanistically distinct, membrane permeant inhibitors (KN-93 and myr-AIP) freezes lamellipodial dynamics, accelerates spreading on fibronectin, enlarges paxillin-containing focal adhesions and blocks cell motility. In contrast, constitutively active CaMK-II is not found at the cell surface, reduces cell attachment, eliminates paxillin from focal adhesions and decreases the phospho-tyrosine levels of both FAK and paxillin; all of these events can be reversed with myr-AIP. Thus, both CaMK-II inhibition and constitutive activation block cell motility through overstabilization or destabilization of focal adhesions, respectively. Coupled with the existence of transient Ca 2+ elevations and a dynamic CaMK-II population, these findings provide the first direct evidence that CaMK-II enables cell motility by transiently and locally stimulating tyrosine dephosphorylation of focal adhesion proteins to promote focal adhesion turnover. Cell Motil.

Cytoskeletal Disassembly and Cell Rounding Promotes Adipogenesis from ES Cells

“…In contrast, nocodazole decreases the activity of CaMKII, which may have multiple, stimulatory effects on cell adhesion. Decreasing the activity of CaMKII may increase focal adhesion-based cellsubstratum adhesion as described before [12,32,34,79,81,83]. Inactivation of c-Src by microtubule depolymerization may help in inhibiting CaMKII activity as c-Src is one of the activators of the CaMKII signalling pathway [19,20].…”

“…Increased activity of CaMKII (as in the case of cytochalasin D treatment) has been shown to diminish cell adhesiveness [81][82][83], and we observe an association between activation of CaMKII and increased cell rounding [12,32,34,79]. CaMKII activation reduces cell adhesiveness by promoting dephosphorylation of focal adhesion kinase and paxillin [83], which reduces their incorporation into focal adhesions and may promote adipogenesis [11,84,85]. In contrast, nocodazole decreases the activity of CaMKII, which may have multiple, stimulatory effects on cell adhesion.…”

Calcium and Calmodulin-dependent Serine/Threonine Protein Kinase Type II (CaMKII)-mediated Intramolecular Opening of Integrin Cytoplasmic Domain-associated Protein-1 (ICAP-1α) Negatively Regulates β1 Integrins

“…CaMKII function in the control of cell adhesion has been demonstrated in several previous reports. CaMKII inhibition accelerates cell spreading on FN, whereas its constitutive activation decreases cell adhesion and destabilizes FAs (22,26). CaMKII activity is largely controlled by an increase in cytoplasmic calcium content within the cell (44).…”

“…CaMKII activity promotes FA turnover (22) and cell migration (23,24). CaMKII is activated following ␣5␤1 integrin engagement and is required for ␣5␤1-dependent cell migration and phagocytosis (25).…”

Sodium-Calcium Exchanger 1 Regulates Epithelial Cell Migration via Calcium-dependent Extracellular Signal-regulated Kinase Signaling

“…Enhanced intracellular calcium can activate PI3K via Ca 2ϩ sensor calmodulin or calmodulin-dependent kinase II, which are key players in calcium-mediated cell migration (35)(36)(37). ␤-KD cells were treated with W-13 or KN-93, which inhibit calmodulin and calmodulin-dependent kinase II, respectively.…”