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Journal Article

Physical state of the extracellular matrix regulates the structure and molecular composition of cell-matrix adhesions


Zamir,  E.
Abt. II: Systemische Zellbiologie, Max Planck Institute of Molecular Physiology, Max Planck Society;

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Katz, B. Z., Zamir, E., Bershadsky, A., Kam, Z., Yamada, K. M., & Geiger, B. (2000). Physical state of the extracellular matrix regulates the structure and molecular composition of cell-matrix adhesions. Molecular Biology of the Cell, 11(3), 1047-1060. Retrieved from http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10712519.

Cite as: http://hdl.handle.net/11858/00-001M-0000-0014-1031-B
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, alpha(5)beta(1) 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, alpha(5)beta(1) 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-alpha(5)beta(1) 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.