Inhibition of Fibronectin Matrix Assembly by the Heparin-binding Domain of Vitronectin

doi:10.1074/jbc.274.38.27257

Inhibition of Fibronectin Matrix Assembly by the Heparin-binding Domain of Vitronectin*

From the Cell and Molecular Biology Program and the Department of Physiology and Cell Biology, Albany Medical College, Albany, New York 12208 and the ^§Department of Experimental Pathology, Lund University, 22185 Lund, Sweden

Abstract

The deposition of fibronectin into the extracellular matrix is an integrin-dependent, multistep process that is tightly regulated in order to ensure controlled matrix deposition. Reduced fibronectin deposition has been associated with altered embryonic development, tumor cell invasion, and abnormal wound repair. In one of the initial steps of fibronectin matrix assembly, the amino-terminal region of fibronectin binds to cell surface receptors, termed matrix assembly sites. The present study was undertaken to investigate the role of extracellular signals in the regulation of fibronectin deposition. Our data indicate that the interaction of cells with the extracellular glycoprotein, vitronectin, specifically inhibits matrix assembly site expression and fibronectin deposition. The region of vitronectin responsible for the inhibition of fibronectin deposition was localized to the heparin-binding domain. Vitronectin’s heparin-binding domain inhibited both β₁ and non-β₁ integrin-dependent matrix assembly site expression and could be overcome by treatment of cells with lysophosphatidic acid, an agent that promotes actin polymerization. The interaction of cells with the heparin-binding domain of vitronectin resulted in changes in actin microfilament organization and the subcellular distribution of the actin-associated proteins α-actinin and talin. These data suggest a mechanism whereby the heparin-binding domain of vitronectin regulates the deposition of fibronectin into the extracellular matrix through alterations in the organization of the actin cytoskeleton.

Footnotes

↵* This work was supported by National Institutes of Health Grants CA-69612 and CA-58626 (to P. J. M.-L.) and HL-50549 (to J. S.) and American Heart Association, New York State Affiliate, Grants 950210 (to D. H.) and 950318 (to J. S.).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.
↵‡ Present address: Dept. of Physiology and Pharmacology, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY 14642-8711.
↵¶ To whom correspondence should be addressed: Cell and Molecular Biology Program, MC-165, Albany Medical College, Albany, NY 12208. Tel.: 518-262-5698; Fax: 518-262-5696; E-mail: Paula_McKeownLongo@ccgateway.amc.edu.
Abbreviations:

LPA

1-oleoyl lysophosphatidic acid

GST

glutathionine S-transferase

DMEM

Dulbecco’s modified Eagle’s medium

PCR

polymerase chain reaction

PBS

phosphate-buffered saline

PMA

phorbol 12-myristate 13-acetate

FnIII

recombinant human fibronectin type III module

Vn

vitronectin
- Received November 23, 1998.
- Revision received April 6, 1999.
The American Society for Biochemistry and Molecular Biology, Inc.