title: Microfibrils at basement membrane zones interact with perlecan via fibrillin-1.
abstract: Mutational defects in fibrillin-rich microfibrils give rise to a number of heritable connective tissue disorders, generally termed microfibrillopathies. To understand the pathogenesis of these microfibrillopathies, it is important to elucidate the supramolecular composition of microfibrils and their interaction properties with extracellular matrix components. Here we demonstrate that the proteoglycan perlecan is an associated component of microfibrils typically close to basement membrane zones. Double immunofluorescence studies demonstrate colocalization of fibrillin-1, the major backbone component of microfibrils, with perlecan in fibroblast cultures as well as in dermal and ocular tissues. Double immunogold labeling further confirms colocalization of perlecan to microfibrils in various tissues at the ultrastructural level. Extraction studies revealed that perlecan is not covalently associated with microfibrils. High affinity interactions between fibrillin-1 and perlecan were found by kinetic binding studies with dissociation constants in the low nanomolar range. A detailed mapping study of the interaction epitopes by solid phase binding assays primarily revealed interactions of perlecan domains I and II with a central region of fibrillin-1. Analysis of perlecan null embryos showed less microfibrils at the dermal-epidermal junction as compared with wild-type littermates. The data presented indicate a functional significance for perlecan in anchoring microfibrils to basement membranes and in the biogenesis of microfibrils.
authors.affiliation: Department of Medical Molecular Biology, University of Lübeck, 23538 Lübeck, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Tiedemann
authors.forename: Takako
authors.initials: T
authors.lastname: Sasaki
authors.forename: Erika
authors.initials: E
authors.lastname: Gustafsson
authors.forename: Walter
authors.initials: W
authors.lastname: Göhring
authors.forename: Boris
authors.initials: B
authors.lastname: Bätge
authors.forename: Holger
authors.initials: H
authors.lastname: Notbohm
authors.forename: Rupert
authors.initials: R
authors.lastname: Timpl
authors.forename: Thilo
authors.initials: T
authors.lastname: Wedel
authors.forename: Ursula
authors.initials: U
authors.lastname: Schlötzer-Schrehardt
authors.forename: Dieter P
authors.initials: DP
authors.lastname: Reinhardt
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000737:chemistry; D000071838:Fibrillin-1; D000071837:Fibrillins; D019084:Fluorescent Antibody Technique, Indirect; D019812:Heparan Sulfate Proteoglycans / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D006497:Heparan Sulfate / Q000032:analysis; D006801:Humans; D051379:Mice; D020894:Microfibrils / Q000737:chemistry* / Q000502:physiology; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D012867:Skin / Q000737:chemistry; D054392:Adipokines
chemical_list: D000071838:Fibrillin-1; D000071837:Fibrillins; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; D008840:Microfilament Proteins; C000605722:FBN1 protein, human; D054392:Adipokines; C000605724:Fbn1 protein, mouse; C071927:perlecan