Regulation of Intercellular Adhesion Strength in Fibroblasts*
- Matthew W. C. Chan‡§,
- Tarek Y. El Sayeghद,
- Pamela D. Arora‡,
- Carol A. Laschinger‡,
- Christopher M. Overall∥,
- Charlotte Morrison∥ and
- Christopher A. G. McCulloch‡
- ‡Canadian Institutes of Health Research (CIHR) Group in Matrix Dynamics, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5S 3E2, and the ∥CIHR Group in Matrix Dynamics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
- ↵¶ To whom correspondence should be addressed: Rm. 243, Fitzgerald Bldg., 150 College St., University of Toronto, Toronto, Ontario, Canada, M5S 3E2. Tel.: 416-978-6684; Fax: 416-978-5956; E-mail: t.elsayegh{at}utoronto.ca.
Abstract
The regulation of adherens junction formation in cells of mesenchymal lineage is of critical importance in tumorigenesis but is poorly characterized. As actin filaments are crucial components of adherens junction assembly, we studied the role of gelsolin, a calcium-dependent, actin severing protein, in the formation of N-cadherin-mediated intercellular adhesions. With a homotypic, donor-acceptor cell model and plates or beads coated with recombinant N-cadherin-Fc chimeric protein, we found that gelsolin spatially co-localizes to, and is transiently associated with, cadherin adhesion complexes. Fibroblasts from gelsolin-null mice exhibited marked reductions in kinetics and strengthening of N-cadherin-dependent junctions when compared with wild-type cells. Experiments with lanthanum chloride (250 μm) showed that adhesion strength was dependent on entry of calcium ions subsequent to N-cadherin ligation. Cadherin-associated gelsolin severing activity was required for localized actin assembly as determined by rhodamine actin monomer incorporation onto actin barbed ends at intercellular adhesion sites. Scanning electron microscopy showed that gelsolin was an important determinant of actin filament architecture of adherens junctions at nascent N-cadherin-mediated contacts. These data indicate that increased actin barbed end generation by the severing activity of gelsolin associated with N-cadherin regulates intercellular adhesion strength.
- Received June 14, 2004.
- The American Society for Biochemistry and Molecular Biology, Inc.
