title: Tissue transglutaminase is an integrin-binding adhesion coreceptor for fibronectin.
abstract: The protein cross-linking enzyme tissue transglutaminase binds in vitro with high affinity to fibronectin via its 42-kD gelatin-binding domain. Here we report that cell surface transglutaminase mediates adhesion and spreading of cells on the 42-kD fibronectin fragment, which lacks integrin-binding motifs. Overexpression of tissue transglutaminase increases its amount on the cell surface, enhances adhesion and spreading on fibronectin and its 42-kD fragment, enlarges focal adhesions, and amplifies adhesion-dependent phosphorylation of focal adhesion kinase. These effects are specific for tissue transglutaminase and are not shared by its functional homologue, a catalytic subunit of factor XIII. Adhesive function of tissue transglutaminase does not require its cross-linking activity but depends on its stable noncovalent association with integrins. Transglutaminase interacts directly with multiple integrins of beta1 and beta3 subfamilies, but not with beta2 integrins. Complexes of transglutaminase with integrins are formed inside the cell during biosynthesis and accumulate on the surface and in focal adhesions. Together our results demonstrate that tissue transglutaminase mediates the interaction of integrins with fibronectin, thereby acting as an integrin-associated coreceptor to promote cell adhesion and spreading.
authors.affiliation: Department of Biochemistry, American Red Cross, Rockville, Maryland 20855, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Akimov
authors.forename: D
authors.initials: D
authors.lastname: Krylov
authors.forename: L F
authors.initials: LF
authors.lastname: Fleischman
authors.forename: A M
authors.initials: AM
authors.lastname: Belkin
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D003432:Cross-Linking Reagents; D005353:Fibronectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D039661:Integrin beta3; D016023:Integrins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011233:Precipitin Tests; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D011503:Transglutaminases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D003432:Cross-Linking Reagents; D005353:Fibronectins; D019012:Integrin beta1; D039661:Integrin beta3; D016023:Integrins; D010446:Peptide Fragments; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; C496052:Ptk2 protein, rat; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate