title: Role of collagen type II and perlecan in skeletal development.
abstract: The cartilage extracellular matrix is composed of a dense collagen network that entraps a range of other specialized proteins important for the proper formation and function of the tissue. Loss of two abundant cartilage components, type II collagen and perlecan, has drastic effects on skeletal development. Both collagen II and perlecan mutants have severe and lethal chondrodysplasia characterized by disorganized growth plate, lack of collagen network, defective endochondral bone formation, and abnormal intervertebral disk development. To test whether the reduced collagen density in the perlecan-null cartilage is due to enhanced activity of collagen-degrading proteinases, we have analyzed gelatinase expression and activity in the mutant tissue. Immunohistochemical analysis revealed a weak, but clear, expansion of MMP-9 deposition into the hypertrophic zone of the perlecan-null growth plate. However, in situ and SDS-PAGE zymography showed that the activity of gelatinases (MMP-2 and MMP-9) is not altered in perlecan-null cartilage, suggesting that they are not primarily linked to the reduced fibrillar network observed in the mutant. Likewise, intercrossing of perlecan mutants onto an MMP-9-null background could not rescue the ultrastructural abnormalities of the perlecan-deficient cartilage.
authors.affiliation: Department of Experimental Pathology, Lund University, 22185 Lund, Sweden.
authors.forename: Erika
authors.initials: E
authors.lastname: Gustafsson
authors.forename: Attila
authors.initials: A
authors.lastname: Aszodi
authors.forename: Nathalie
authors.initials: N
authors.lastname: Ortega
authors.forename: Ernst B
authors.initials: EB
authors.lastname: Hunziker
authors.forename: Hans-Werner
authors.initials: HW
authors.lastname: Denker
authors.forename: Zena
authors.initials: Z
authors.lastname: Werb
authors.forename: Reinhard
authors.initials: R
authors.lastname: Fassler
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000033:anatomy & histology / Q000196:embryology*; D002356:Cartilage / Q000196:embryology / Q000648:ultrastructure; D024043:Collagen Type II / Q000235:genetics / Q000502:physiology*; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000201:enzymology / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000648:ultrastructure; D024022:Fibrillar Collagens / Q000648:ultrastructure; D018093:Gelatinases / Q000378:metabolism; D019812:Heparan Sulfate Proteoglycans / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D010009:Osteochondrodysplasias / Q000209:etiology; D010012:Osteogenesis
chemical_list: D024043:Collagen Type II; D024022:Fibrillar Collagens; D019812:Heparan Sulfate Proteoglycans; C071927:perlecan; D018093:Gelatinases