Genetic ablation of zyxin causes Mena/VASP mislocalization, increased motility, and deficits in actin remodeling.
Focal adhesions are specialized regions of the cell surface where integrin receptors and associated proteins link the extracellular matrix to the actin cytoskeleton. To define the cellular role of the focal adhesion protein zyxin, we characterized the phenotype of fibroblasts in which the zyxin gene was deleted by homologous recombination. Zyxin-null fibroblasts display enhanced integrin-dependent adhesion and are more migratory than wild-type fibroblasts, displaying reduced dependence on extracellular matrix cues. We identified differences in the profiles of 75- and 80-kD tyrosine-phosphorylated proteins in the zyxin-null cells. Tandem array mass spectrometry identified both modified proteins as isoforms of the actomyosin regulator caldesmon, a protein known to influence contractility, stress fiber formation, and motility. Zyxin-null fibroblasts also show deficits in actin stress fiber remodeling and exhibit changes in the molecular composition of focal adhesions, most notably by severely reduced accumulation of Ena/VASP proteins. We postulate that zyxin cooperates with Ena/VASP proteins and caldesmon to influence integrin-dependent cell motility and actin stress fiber remodeling.
Hoffman
Laura M
LM
The Huntsman Cancer Institute and the Department of Biology,University of Utah, Salt Lake City, UT 84112, USA.
Jensen
Christopher C
CC
Kloeker
Susanne
S
Wang
C-L Albert
CL
Yoshigi
Masaaki
M
Beckerle
Mary C
MC
D000199:Actins / Q000172:deficiency / Q000378:metabolism*; D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002448:Cell Adhesion / Q000235:genetics; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002461:Cell Line, Transformed; D002465:Cell Movement / Q000235:genetics*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D047630:Depsipeptides / Q000494:pharmacology; D005109:Extracellular Matrix / Q000502:physiology; D005347:Fibroblasts / Q000378:metabolism; D016023:Integrins / Q000096:biosynthesis / Q000235:genetics; D008667:Metalloproteins / Q000172:deficiency* / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism*; D022502:Stress Fibers / Q000187:drug effects; D060589:Zyxin; D000098662:Vasodilator-Stimulated Phosphoprotein
D000199:Actins; D002148:Calmodulin-Binding Proteins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D047630:Depsipeptides; C102176:Enah protein, mouse; D016023:Integrins; D008667:Metalloproteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; C498285:Zyx protein, mouse; D060589:Zyxin; D000098662:Vasodilator-Stimulated Phosphoprotein; C057531:jasplakinolide