Physical State of the Extracellular Matrix Regulates the Structure and Molecular Composition of Cell-Matrix Adhesions
AUTOR(ES)
Katz, Ben-Zion
FONTE
The American Society for Cell Biology
RESUMO
This study establishes that the physical state of the extracellular matrix can regulate integrin-mediated cytoskeletal assembly and tyrosine phosphorylation to generate two distinct types of cell-matrix adhesions. In primary fibroblasts, α5β1 integrin associates mainly with fibronectin fibrils and forms adhesions structurally distinct from focal contacts, independent of actomyosin-mediated cell contractility. These “fibrillar adhesions” are enriched in tensin, but contain low levels of the typical focal contact components paxillin, vinculin, and tyrosine-phosphorylated proteins. However, when the fibronectin is covalently linked to the substrate, α5β1 integrin forms highly tyrosine-phosphorylated, “classical” focal contacts containing high levels of paxillin and vinculin. These experiments indicate that the physical state of the matrix, not just its molecular composition, is a critical factor in defining cytoskeletal organization and phosphorylation at adhesion sites. We propose that molecular organization of adhesion sites is controlled by at least two mechanisms: 1) specific integrins associate with their ligands in transmembrane complexes with appropriate cytoplasmic anchor proteins (e.g., fibronectin–α5β1 integrin–tensin complexes), and 2) physical properties (e.g., rigidity) of the extracellular matrix regulate local tension at adhesion sites and activate local tyrosine phosphorylation, recruiting a variety of plaque molecules to these sites. These mechanisms generate structurally and functionally distinct types of matrix adhesions in fibroblasts.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=14830Documentos Relacionados
- Fibronectin Polymerization Regulates the Composition and Stability of Extracellular Matrix Fibrils and Cell-Matrix Adhesions
- Cell-Matrix Adhesions Differentially Regulate Fascin Phosphorylation
- Basal Extracellular Signal-Regulated Kinase Activity Modulates Cell-Cell and Cell-Matrix Interactions
- Extracellular protons acidify osteoclasts, reduce cytosolic calcium, and promote expression of cell-matrix attachment structures.
- Active ERK/MAP kinase is targeted to newly forming cell–matrix adhesions by integrin engagement and v-Src