Inhibition of c-Abl Tyrosine Kinase Activity by Filamentous Actin

Abstract

The catalytic activity of c-Abl tyrosine kinase is reduced in fibroblasts that are detached from the extracellular matrix. We report here that a deletion of the extreme C terminus of c-Abl (

Cytoplasmic c-Abl provides a molecular ‘Rheostat’ controlling carcinoma cell survival and invasion

“…Changes in p73 tyrosine phosphorylation were determined by densitometry relative to the total p73 protein present in the immunoprecipitates While we demonstrate that deregulation of the Abl 'rheostat' leads to increased Crk/CAS coupling, Abl activity is normally tightly regulated by a complex balance of positive and negative inputs from intra-and extracellular factors that control cell movement and survival (Dai and Pendergast, 1995;Lewis et al, 1996;Plattner et al, 1999;Fan and Goff, 2000;Woodring et al, 2001;Pluk et al, 2002). Abl activity is regulated by integrins, growth factors, oxidative and genotoxic stress, as well as through intracellular mechanisms that involve autoregulation, src kinase, and several Ablbinding proteins including actin (Lewis et al, 1996;Lewis and Schwartz 1998;Plattner et al, 1999;Woodring et al, 2001Woodring et al, , 2002. Furthermore, Abl protein shuttles to different intracellular compartments, adding another level of complexity to its regulation and substrate diversity (Lewis et al, 1996;Wen et al, 1996;Woodring et al, 2001).…”

“…(d) Lysates from these cells were examined by measuring the relative decrease in Crk protein mobility by SDS-PAGE and immunoblotting, and densitometry was used to determine the percent of phosphorylated Crk as described above in constitutive activation of Abl (for a review, see Smith and Mayer, 2002) (Figure 4e), and is also required for Abl interaction with p73 (Agami et al, 1999;Yuan et al, 1999). Reconstitution of A/AÀ/À cells with Abl lacking the SH3 domain (Abl SH3) (Woodring et al, 2001) inhibited cell migration, and induced strong apoptosis as a result of increased Crk phosphorylation and decreased Crk/CAS coupling (Figure 4b-d). The reduced Abl DSH3 expression in these cells (Figure 4c) likely results from the increased apoptotic rate of cells expressing elevated levels of the mutant protein in culture as well as increased ubiquitin-mediated degradation of active Abl, as previously reported (Echarri and Pendergast, 2001).…”

F-actin-binding domain of c-Abl regulates localized phosphorylation of C3G: role of C3G in c-Abl-mediated cell death

“…As localized Abl activation is dependent on an intact cytoskeleton and on the FABD of c-Abl, we suggest that F-actin binding regulates c-Abl activation. It is known that reciprocal relationship exists with respect to c-Abl and F-actin interactions, in which the kinase can remodel actin, and F-actin can regulate c-Abl's ability to phosphorylate specific target proteins (Woodring et al, 2001(Woodring et al, , 2005. In stimulated neutrophils, c-Abl activity increases concomitant with an increase in F-actin concentration (Chen et al, 2006) and c-Abl regulates actin remodelling at immune synapse (Huang et al, 2008b).…”

“…c-Abl with deletion of its actin-binding domain (DFABD) was generated by inserting a stop codon after amino-acid 1119 at C-terminal of c-Abl-pSGT construct. This protein lacks ability to bind F-actin (Woodring et al, 2001).…”

Nucleo-cytoplasmic communication in apoptotic response to genotoxic and inflammatory stress

“…The C-terminal region of Abl contains subcellular location cues, including NLS, NES, binding sites for G-actin, F-actin and binding site for DNA [10,11]. We have shown that F-actin, but not G-actin, is an allosteric inhibitor of Abl tyrosine kinase [15]. F-actin functions as a "coinhibitor", enforcing or stabilizing the "auto-inhibited" conformation to inhibit Abl kinase activity [14].…”