RGD-independent cell adhesion via a tissue transglutaminase-fibronectin matrix promotes fibronectin fibril deposition and requires syndecan-4/2 α5β1 integrin co-signaling

J Biol Chem. 2010 Dec 17;285(51):40212-29. doi: 10.1074/jbc.M110.123703. Epub 2010 Oct 7.

Abstract

Fibronectin (FN) deposition mediated by fibroblasts is an important process in matrix remodeling and wound healing. By monitoring the deposition of soluble biotinylated FN, we show that the stress-induced TG-FN matrix, a matrix complex of tissue transglutaminase (TG2) with its high affinity binding partner FN, can increase both exogenous and cellular FN deposition and also restore it when cell adhesion is interrupted via the presence of RGD-containing peptides. This mechanism does not require the transamidase activity of TG2 but is activated through an RGD-independent adhesion process requiring a heterocomplex of TG2 and FN and is mediated by a syndecan-4 and β1 integrin co-signaling pathway. By using α5 null cells, β1 integrin functional blocking antibody, and a α5β1 integrin targeting peptide A5-1, we demonstrate that the α5 and β1 integrins are essential for TG-FN to compensate RGD-induced loss of cell adhesion and FN deposition. The importance of syndecan-2 in this process was shown using targeting siRNAs, which abolished the compensation effect of TG-FN on the RGD-induced loss of cell adhesion, resulting in disruption of actin skeleton formation and FN deposition. Unlike syndecan-4, syndecan-2 does not interact directly with TG2 but acts as a downstream effector in regulating actin cytoskeleton organization through the ROCK pathway. We demonstrate that PKCα is likely to be the important link between syndecan-4 and syndecan-2 signaling and that TG2 is the functional component of the TG-FN heterocomplex in mediating cell adhesion via its direct interaction with heparan sulfate chains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / genetics
  • Actins / metabolism
  • Animals
  • CHO Cells
  • Cell Adhesion / drug effects
  • Cell Adhesion / genetics
  • Cricetinae
  • Cricetulus
  • Cytoskeleton / genetics
  • Cytoskeleton / metabolism
  • Extracellular Matrix / genetics
  • Extracellular Matrix / metabolism*
  • Fibronectins / genetics
  • Fibronectins / metabolism*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • Heparitin Sulfate / genetics
  • Heparitin Sulfate / metabolism
  • Humans
  • Integrin alpha5beta1 / genetics
  • Integrin alpha5beta1 / metabolism*
  • Mice
  • Mice, Mutant Strains
  • Oligopeptides / pharmacology*
  • Protein Glutamine gamma Glutamyltransferase 2
  • Protein Kinase C-alpha / genetics
  • Protein Kinase C-alpha / metabolism
  • RNA, Small Interfering / genetics
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • Syndecan-2 / genetics
  • Syndecan-2 / metabolism*
  • Syndecan-4 / genetics
  • Syndecan-4 / metabolism*
  • Transglutaminases / genetics
  • Transglutaminases / metabolism*
  • rho-Associated Kinases / genetics
  • rho-Associated Kinases / metabolism

Substances

  • Actins
  • Fibronectins
  • Integrin alpha5beta1
  • Oligopeptides
  • RNA, Small Interfering
  • SDC2 protein, human
  • SDC4 protein, human
  • Sdc2 protein, mouse
  • Sdc4 protein, mouse
  • Syndecan-4
  • Syndecan-2
  • arginyl-glycyl-aspartic acid
  • Heparitin Sulfate
  • Protein Glutamine gamma Glutamyltransferase 2
  • Transglutaminases
  • rho-Associated Kinases
  • Protein Kinase C-alpha
  • GTP-Binding Proteins