The Abl-related Gene Tyrosine Kinase Acts through p190RhoGAP to Inhibit Actomyosin Contractility and Regulate Focal Adhesion Dynamics upon Adhesion to Fibronectin

Abstract

In migrating cells, actin polymerization promotes protrusion of the leading edge, whereas actomyosin contractility powers net cell body translocation. Although they promote F-actin-dependent protrusions of the cell periphery upon adhesion to fibronectin (FN), Abl family kinases inhibit cell migration on FN. We provide evidence here that the Abl-related gene (Arg/Abl2) kinase inhibits fibroblast migration by attenuating actomyosin contractility and regulating focal adhesion dynamics. arg؊/؊ fibroblasts migrate at faster average speeds than wild-type (wt) cells, whereas Arg re-expression in these cells slows migration. Surprisingly, the faster migrating arg؊/؊ fibroblasts have more prominent F-actin stress fibers and focal adhesions and exhibit increased actomyosin contractility relative to wt cells. Interestingly, Arg requires distinct functional domains to inhibit focal adhesions and actomyosin contractility. The kinase domain-containing Arg N-terminal half can act through the RhoA inhibitor p190RhoGAP to attenuate stress fiber formation and cell contractility. However, Arg requires both its kinase activity and its cytoskeleton-binding C-terminal half to fully inhibit focal adhesions. Although focal adhesions do not turn over efficiently in the trailing edge of arg؊/؊ cells, the increased contractility of arg؊/؊ cells tears the adhesions from the substrate, allowing for the faster migration observed in these cells. Together, our data strongly suggest that Arg inhibits cell migration by restricting actomyosin contractility and regulating its coupling to the substrate through focal adhesions.

Genomic and genome-wide association of susceptibility to radiation-induced fibrotic lung disease in mice

“…For example, pulmonary fibrosis can occur as a result of increased extracellular matrix deposition and genes involved in this process such as Abl2 and Ddr1 [42,43] were identified to have variation significantly associated with the trait. Supporting this, Ddr1 -/-mice have been shown to develop a reduced amount of pulmonary fibrosis in response to a related challenge, that of bleomycin-induced lung injury [44], and in separate work [45], to be protected from renal fibrosis.…”

Regulation of cell migration and morphogenesis by Abl-family kinases: emerging mechanisms and physiological contexts

“…As discussed above, Abl-family kinases stimulate actin polymerization, leading to cellular protrusion, the first step in cell motility. Surprisingly, however, fibroblasts that are deficient for Abl and/or Arg migrate faster than wild-type controls (Kain and Klemke, 2001;Peacock et al, 2007), and reconstitution with Abl or Arg slows these cells. Here, we describe evidence that Abl-family kinases act through the GTPase RhoA and other mechanisms to attenuate cell migration by modulating cell adhesion and contractility.…”

“…Because active Rho is membrane-bound, Arg dictates the ability of p190 to inhibit Rho by modulating p190 localization. With elevated Rho activity, Arg -/-fibroblasts are highly contractile (Peacock et al, 2007). Reconstitution of these cells with wild-type, but not kinase-inactive, Arg restores p190 phosphorylation and localization, and reduces Rho activity and contractility to normal levels.…”

Inhibition of Rho via Arg and p190RhoGAP in the Postnatal Mouse Hippocampus Regulates Dendritic Spine Maturation, Synapse and Dendrite Stability, and Behavior

“…p190RhoGAP phosphorylation and binding to p120RasGAP are reduced in arg Ϫ/Ϫ hippocampus After integrin-mediated fibroblast adhesion to fibronectin, Arg acts via its substrate p190RhoGAP (p190) to inhibit Rho and attenuate actomyosin contractility (Hernandez et al, 2004;Bradley et al, 2006;Peacock et al, 2007). As a first step toward understanding whether p190 mediates the effects of Arg on hippocampal synapse morphology and dendrite stability, we examined p190 localization and activity.…”

“…This genetic analysis indicates that Abl performs a function that is required for the development of a phenotype in arg Ϫ/Ϫ mice and points to different functions for these kinases in hippocampal dendrites. arg Ϫ/Ϫ fibroblasts, which lack Arg/p190RhoGAP-dependent inhibition of Rho, are hypercontractile and have more prominent adhesions and stress fibers than WT cells (Peacock et al, 2007). Abl mediates signaling from integrin receptors (Lewis et al, 1996).…”