Stimulation of Integrin-mediated Cell Contractility by Fibronectin Polymerization*
- From the ‡Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642 and the ¶Department of Physiology and Cell Biology, Albany Medical College, Albany, New York 12208
Abstract
Ligation of integrins with extracellular matrix molecules induces the clustering of actin and actin-binding proteins to focal adhesions, which serves to mechanically couple the matrix with the cytoskeleton. During wound healing and development, matrix deposition and remodeling may impart additional tensile forces that modulate integrin-mediated cell functions, including cell migration and proliferation. We have utilized the ability of cells to contract floating collagen gels to determine the effect of fibronectin polymerization on mechanical tension generation by cells. Our data indicate that fibronectin polymerization promotes cell spreading in collagen gels and stimulates cell contractility by a Rho-dependent mechanism. Fibronectin-stimulated contractility was dependent on integrin ligation; however, integrin ligation by fibronectin fragments was not sufficient to induce either tension generation or cell spreading. Furthermore, treatment of cells with polyvalent RGD peptides or pre-polymerized fibronectin did not stimulate cell contractility. Fibronectin-induced contractility was blocked by agents that inhibit fibronectin polymerization, suggesting that the process of fibronectin polymerization is critical in triggering cytoskeletal tension generation. These data indicate that Rho-mediated cell contractility is regulated by the process of fibronectin polymerization and suggest a novel mechanism by which extracellular matrix fibronectin regulates cytoskeletal organization and cell function.
Footnotes
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↵* This work was supported by Grants HL60181 (to D. H.), HL 64074 (to D. H.), HL50549 (to J. S.), and HL03971 (to J. S.) of the National Institutes of Health.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵§ To whom correspondence should be addressed: ‡Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave., Box 711, Rochester, NY 14642. Tel.: 716-273-1770; Fax: 716-244-9283; E-mail: denise_hocking@urmc.rochester.edu.
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↵‖ Supported by NIH Predoctoral Training Grant T32-HL07194.
- Abbreviations:
- PAGE
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polyacrylamide gel electrophoresis
- DMEM
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Dulbecco's modified Eagle's media
- BSA
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bovine serum albumin
- PCR
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polymerase chain reaction
- LPA
-
1-oleoyl lysophosphatidic acid
- mAb
-
monoclonal antibody
- FITC
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fluorescein isothiocyanate
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- Received June 28, 1999.
- Revision received December 16, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
