title: Exposure of cryptic domains in the alpha 1-chain of laminin-1 by elastase stimulates macrophages urokinase and matrix metalloproteinase-9 expression.
abstract: Degradation of the extracellular matrix leads to the release of fragments, which elicit biological responses distinct from intact molecules. We have reported that alpha1:Ser(2091)-Arg(2108), a peptide derived from the alpha1-chain of laminin-1, triggers protein kinase C-dependent activation of MAPK(erk1/2), leading to the up-regulation of macrophage urokinase type plasminogen activator and matrix metalloproteinase (MMP)-9 expression. Since intact laminin-1 failed to trigger these events, we hypothesized that alpha1:Ser(2091)-Arg(2108) is cryptic or assumes a conformation not recognized by macrophages. Here we demonstrate that elastase cleavage of laminin-1 generates fragments, which stimulate proteinase expression by RAW264.7 macrophages and peritoneal macrophages. In contrast, fragments generated by MMP-2, MMP-7, or plasmin had no effect on macrophage proteinase expression. Elastase-generated laminin-1 fragments were fractionated by heparin-Sepharose chromatography. Heparin-binding fragments stimulated macrophages' proteinase expression severalfold greater than nonbinding fragments. The heparin binding fragments reacted with antibodies directed against regions of the alpha1-chain including alpha1:Ser(2091)-Arg(2108) and the globular domain. A peptide from the first loop of the globular domain (alpha1:Ser(2179)-Ser(2198)) triggered the phosphorylation of MAPK(erk1/2) and stimulated the expression of macrophage urokinase type plasminogen activator and MMP-9. Moreover, a heparin-binding fraction isolated from an aortic aneurysm contained fragments of alpha1-chain and stimulated macrophages' proteinase expression. Based on these data, we conclude that cryptic domains in the COOH-terminal portion of the alpha1-chain of laminin are exposed by proteolysis and stimulate macrophages' proteinase expression.
authors.affiliation: Department of Pathology, Joan and Sanford I. Weill Medical College of Cornell University, New York, New York 10021, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Faisal Khan
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Laurie
authors.forename: Timothy A
authors.initials: TA
authors.lastname: McCaffrey
authors.forename: Domenick J
authors.initials: DJ
authors.lastname: Falcone
mesh_terms: D000818:Animals; D001014:Aortic Aneurysm / Q000378:metabolism; D001120:Arginine / Q000737:chemistry; D015153:Blotting, Western; D002417:Cattle; D002460:Cell Line; D002845:Chromatography; D005341:Fibrinolysin / Q000378:metabolism; D006801:Humans; D007797:Laminin / Q000737:chemistry* / Q000378:metabolism; D008264:Macrophages / Q000201:enzymology* / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020783:Matrix Metalloproteinase 7 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis*; D051379:Mice; D010196:Pancreatic Elastase / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012694:Serine / Q000737:chemistry; D013997:Time Factors; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis*
chemical_list: D007797:Laminin; D010455:Peptides; C121346:laminin 1; D012694:Serine; D001120:Arginine; D011493:Protein Kinase C; D010196:Pancreatic Elastase; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; D020783:Matrix Metalloproteinase 7; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9