title: Lysyl Oxidase Activity Is Required for Ordered Collagen Fibrillogenesis by Tendon Cells.
abstract: Lysyl oxidases (LOXs) are a family of copper-dependent oxido-deaminases that can modify the side chain of lysyl residues in collagen and elastin, thereby leading to the spontaneous formation of non-reducible aldehyde-derived interpolypeptide chain cross-links. The consequences of LOX inhibition in producing lathyrism are well documented, but the consequences on collagen fibril formation are less clear. Here we used β-aminoproprionitrile (BAPN) to inhibit LOX in tendon-like constructs (prepared from human tenocytes), which are an experimental model of cell-mediated collagen fibril formation. The improvement in structure and strength seen with time in control constructs was absent in constructs treated with BAPN. As expected, BAPN inhibited the formation of aldimine-derived cross-links in collagen, and the constructs were mechanically weak. However, an unexpected finding was that BAPN treatment led to structurally abnormal collagen fibrils with irregular profiles and widely dispersed diameters. Of special interest, the abnormal fibril profiles resembled those seen in some Ehlers-Danlos Syndrome phenotypes. Importantly, the total collagen content developed normally, and there was no difference in COL1A1 gene expression. Collagen type V, decorin, fibromodulin, and tenascin-X proteins were unaffected by the cross-link inhibition, suggesting that LOX regulates fibrillogenesis independently of these molecules. Collectively, the data show the importance of LOX for the mechanical development of early collagenous tissues and that LOX is essential for correct collagen fibril shape formation.
authors.affiliation: From the Institute of Sports Medicine Copenhagen and Center for Healthy Ageing, University of Copenhagen, DK-2400 Copenhagen, Denmark, andreas.herchenhan@gmail.com.
authors.forename: Andreas
authors.initials: A
authors.lastname: Herchenhan
authors.affiliation: Section for Experimental Animal Models, Laboratory of Immunology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark.
authors.forename: Franziska
authors.initials: F
authors.lastname: Uhlenbrock
authors.affiliation: From the Institute of Sports Medicine Copenhagen and Center for Healthy Ageing, University of Copenhagen, DK-2400 Copenhagen, Denmark.
authors.forename: Pernilla
authors.initials: P
authors.lastname: Eliasson
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington 98195-6500, and.
authors.forename: MaryAnn
authors.initials: M
authors.lastname: Weis
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington 98195-6500, and.
authors.forename: David
authors.initials: D
authors.lastname: Eyre
authors.affiliation: Wellcome Trust Center for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
authors.forename: Karl E
authors.initials: KE
authors.lastname: Kadler
authors.affiliation: From the Institute of Sports Medicine Copenhagen and Center for Healthy Ageing, University of Copenhagen, DK-2400 Copenhagen, Denmark.
authors.forename: S Peter
authors.initials: SP
authors.lastname: Magnusson
authors.affiliation: From the Institute of Sports Medicine Copenhagen and Center for Healthy Ageing, University of Copenhagen, DK-2400 Copenhagen, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
mesh_terms: D000293:Adolescent; D000328:Adult; D004535:Ehlers-Danlos Syndrome / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D005260:Female; D024022:Fibrillar Collagens / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008249:Protein-Lysine 6-Oxidase / Q000235:genetics / Q000378:metabolism*; D013710:Tendons / Q000201:enzymology* / Q000378:metabolism; D055815:Young Adult
chemical_list: D024022:Fibrillar Collagens; D008249:Protein-Lysine 6-Oxidase
keywords: Ehlers-Danlos Syndrome; collagen; collagen cross-linking; electron microscopy (EM); fibril; lysyl oxidase; tendon; tendon construct; β-aminoproprionitrile (BAPN)