title: A paxillin tyrosine phosphorylation switch regulates the assembly and form of cell-matrix adhesions.
abstract: Diverse cellular processes are carried out by distinct integrin-mediated adhesions. Cell spreading and migration are driven by focal complexes; robust adhesion to the extracellular matrix by focal adhesions; and matrix remodeling by fibrillar adhesions. The mechanism(s) regulating the spatio-temporal distribution and dynamics of the three types of adhesion are unknown. Here, we combine live-cell imaging, labeling with phosphospecific-antibodies and overexpression of a novel tyrosine phosphomimetic mutant of paxillin, to demonstrate that the modulation of tyrosine phosphorylation of paxillin regulates both the assembly and turnover of adhesion sites. Moreover, phosphorylated paxillin enhanced lamellipodial protrusions, whereas non-phosphorylated paxillin was essential for fibrillar adhesion formation and for fibronectin fibrillogenesis. We further show that focal adhesion kinase preferentially interacted with the tyrosine phosphomimetic paxillin and its recruitment is implicated in high turnover of focal complexes and translocation of focal adhesions. We created a mathematical model that recapitulates the salient features of the measured dynamics, and conclude that tyrosine phosphorylation of the adaptor protein paxillin functions as a major switch, regulating the adhesive phenotype of cells.
authors.affiliation: Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Ronen
authors.initials: R
authors.lastname: Zaidel-Bar
authors.forename: Ron
authors.initials: R
authors.lastname: Milo
authors.forename: Zvi
authors.initials: Z
authors.lastname: Kam
authors.forename: Benjamin
authors.initials: B
authors.lastname: Geiger
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001011:Aorta / Q000166:cytology; D002448:Cell Adhesion / Q000502:physiology*; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology*; D005109:Extracellular Matrix / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology; D005353:Fibronectins / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D016023:Integrins / Q000378:metabolism; D008954:Models, Biological; D016296:Mutagenesis; D051419:Paxillin / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D011554:Pseudopodia / Q000201:enzymology; D051381:Rats; D013314:Stress, Mechanical; D013552:Swine; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000906:Antibodies; D005353:Fibronectins; D016023:Integrins; D051419:Paxillin; D014443:Tyrosine; D051416:Focal Adhesion Protein-Tyrosine Kinases