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| Research article summary (published 31 Jan 2009): |
Scaffold-forming and Adhesive Contributions of Synthetic Laminin-binding Proteins to Basement Membrane Assembly.
Full Abstract
Laminins that possess three short arms contribute to basement membrane assembly by anchoring to cell surfaces, polymerizing, and binding to nidogen and collagen IV. Although laminins containing the alpha4 and alpha5 subunits are expressed in alpha2-deficient congenital muscular dystrophy, they may be ineffective substitutes because they bind weakly to cell surfaces and/or because they lack the third arm needed for polymerization. We asked whether linker proteins engineered to bind to deficient laminins that provide such missing activities would promote basement membrane assembly in a Schwann cell model. A chimeric fusion protein (alphaLNNd) that adds a short arm terminus to laminin through the nidogen binding locus was generated and compared with the dystrophy-ameliorating protein miniagrin (mAgrin) that binds to the laminin coiled-coil dystroglycan and sulfatides. alphaLNNd was found to mediate laminin binding to collagen IV, to bind to galactosyl sulfatide, and to selectively convert alpha-short arm deletion-mutant laminins LmDeltaalphaLN and LmDeltaalphaLN-L4b into polymerizing laminins. This protein enabled polymerization-deficient laminin but not an adhesion-deficient laminin lacking LG domains (LmDeltaLG) to assemble an extracellular matrix on Schwann cell surfaces. mAgrin, on the other hand, enabled LmDeltaLG to form an extracellular matrix on cell surfaces without increasing accumulation of non-polymerizing laminins. These gain-of-function studies reveal distinct polymerization and anchorage contributions to basement membrane assembly in which the three different LN domains mediate the former, and the LG domains provide primary anchorage with secondary contributions from the alphaLN domain. These findings may be relevant for an understanding of the pathogenesis and treatment of laminin deficiency states.
Author information
Author/s: McKee, Karen K (KK); Capizzi, Stephanie (S); Yurchenco, Peter D (PD);
Affiliation: Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
Grants: R01-NS38469 (Agency:NINDS NIH HHS) ; R37-DK36425 (Agency:NIDDK NIH HHS)
Journal and publication information
Publication Type: Journal Article; Research Support, N.I.H., Extramural
Journal: The Journal of biological chemistry (J Biol Chem), published in United States. (Language: eng)
Reference: 2009-Mar; vol 284 (issue 13) : pp 8984-94
Dates: Created 2009/03/23; Completed 2009/05/26;
PMID: 19189961, status: MEDLINE (last retrieval date: 5/26/2009, IMS Date: )
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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