title: Regulation of intercellular adhesion strength in fibroblasts.
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 microm) 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.
authors.affiliation: Canadian Institutes of Health Research (CIHR) Group in Matrix Dynamics, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5S 3E2, Canada.
authors.forename: Matthew W C
authors.initials: MW
authors.lastname: Chan
authors.forename: Tarek Y
authors.initials: TY
authors.lastname: El Sayegh
authors.forename: Pamela D
authors.initials: PD
authors.lastname: Arora
authors.forename: Carol A
authors.initials: CA
authors.lastname: Laschinger
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Overall
authors.forename: Charlotte
authors.initials: C
authors.lastname: Morrison
authors.forename: Christopher A G
authors.initials: CA
authors.lastname: McCulloch
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000737:chemistry / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D019070:Cell Lineage; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D015536:Down-Regulation; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D005434:Flow Cytometry; D018260:Gelsolin / Q000737:chemistry; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology; D008280:Magnetics; D051379:Mice; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D008954:Models, Biological; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: D000199:Actins; D015820:Cadherins; C502403:FAT1 protein, human; C502405:Fat1 protein, rat; D018260:Gelsolin; D011994:Recombinant Proteins; C502406:fat1 protein, mouse; C028521:lanthanum chloride; D007811:Lanthanum; D002118:Calcium