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First published online 24 July 2008
doi: 10.1242/jcs.029819
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Research Article |
1 Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Science, Michael Smith Building, Oxford Road, University of Manchester, Manchester M13 9PT, UK
2 Max Planck Institute of Biochemistry, Department of Molecular Medicine, Am Klopferspitz 18, 82152 Martinsried, Germany
* Author for correspondence (e-mail: cay.kielty{at}manchester.ac.uk)
Accepted 3 June 2008
Newly deposited microfibrils strongly colocalise with fibronectin in primary fibroblasts. Microfibril formation is grossly inhibited by fibronectin depletion, but rescued by supplementation with exogenous cellular fibronectin. As integrin receptors are key determinants of fibronectin assembly, we investigated whether they also influenced microfibril deposition. Analysis of β1-integrin-receptor-null fibroblasts, blockage of cell surface integrin receptors that regulate fibronectin assembly and disruption of Rho kinase all result in suppressed deposition of both fibronectin and microfibrils. Antibody activation of β1 integrins in fibronectin-depleted cultures is insufficient to rescue microfibril assembly. In fibronectinRGE/RGE mutant mouse fibroblast cultures, which do not engage
5β1 integrin, extracellular assembly of both fibronectin and microfibrils is markedly reduced. Thus, pericellular microfibril assembly is regulated by fibronectin fibrillogenesis.
Key words: Fibrillin-1, Microfibrils, Fibronectin, Integrin, Rho kinase