| 1. |
- Skiöldebrand, Eva, et al.
(författare)
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Ultrastructural immunolocalization of cartilage oligomeric matrix protein (COMP) in the articular cartilage on the equine third carpal bone in trained and untrained horses
- 2010
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Ingår i: Research in Veterinary Science. - : Elsevier BV. - 0034-5288 .- 1532-2661. ; 88:2, s. 251-257
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Tidskriftsartikel (refereegranskat)abstract
- The present study was designed to delineate the presence of COMP at the ultrastructural level comparing concentrations between two areas of articular cartilage from the equine third carpal bone, subjected to different loading, from trained and untrained horses. We also analyzed the fibril thickness of collagen type II in the same compartments and zones. Samples were collected from high load-bearing areas of the dorsal radial facet (intermittent high load) and an area of the palmar condyle (low constant load) in five non-trained and three trained young racehorses. The data show that COMP is much less abundant in the matrix in intermittent high loaded areas of articular cartilage from trained horses as compared to the untrained horses (p = 0.036). On the other hand, the untrained horses often displayed a higher immunolabeling in loaded areas compared to unloaded areas, indicating that an adequate dynamic load promotes COMP synthesis and/or retention, while an excessive load may have an opposite effect. The collagen fibril diameter showed marked variation between individuals. The present study indicates that dynamic in vivo compression at high load and frequency lowers matrix content of COMP in the articular cartilage of the third carpal bone. It also indicates that the collagen network is influenced by mechanical load following by strenuous exercise. (C) 2009 Elsevier Ltd. All rights reserved.
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| 2. |
- Södersten, Fredrik, et al.
(författare)
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Immunolocalization of Collagens (I and III) and Cartilage Oligomeric Matrix Protein in the Normal and Injured Equine Superficial Digital Flexor Tendon
- 2013
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Ingår i: Connective Tissue Research. - : Informa UK Limited. - 1607-8438 .- 0300-8207. ; 54:1, s. 62-69
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Tidskriftsartikel (refereegranskat)abstract
- This is a descriptive study of tendon pathology with different structural appearances of repair tissue correlated to immunolocalization of cartilage oligomeric matrix protein (COMP) and type I and III collagens and expression of COMP mRNA. The material consists of nine tendons from seven horses (5-25 years old; mean age of 10 years) with clinical tendinopathy and three normal tendons from horses (3, 3, and 13 years old) euthanized for non-orthopedic reasons. The injured tendons displayed different repair-tissue appearances with organized and disorganized fibroblastic regions as well as areas of necrosis. The normal tendons presented distinct immunoreactivity for COMP and expression of COMP mRNA and type I collagen in the normal aligned fiber structures, but no immunolabeling of type III collagen. However, immunoreactivity for type III collagen was present in the endotenon surrounding the fiber bundles, where no expression of COMP could be seen. Immunostaining for type I and III collagens was present in all of the pathologic regions indicating repair tissue. Interestingly, the granulation tissues showed immunostaining for COMP and expression of COMP mRNA, indicating a role for COMP in repair and remodeling of the tendon after fiber degeneration and rupture. The present results suggest that not only type III collagen but also COMP is involved in the repair and remodeling processes of the tendon.
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| 3. |
- van Wieringen, Tijs, et al.
(författare)
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The streptococcal collagen-binding protein CNE specifically interferes with {alpha}V{beta}3-mediated cellular interactions with triple helical collagen
- 2010
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 285:46, s. 35803-35813
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Tidskriftsartikel (refereegranskat)abstract
- Collagen fibers expose distinct domains allowing for specific interactions with other extracellular matrix proteins and cells. To investigate putative collagen domains that govern integrin α(V)β(3)-mediated cellular interactions with native collagen fibers we took advantage of the streptococcal protein CNE that bound native fibrillar collagens. CNE specifically inhibited α(V)β(3)-dependent cell-mediated collagen gel contraction, PDGF BB-induced and α(V)β(3)-mediated adhesion of cells, and binding of fibronectin to native collagen. Using a Toolkit composed of overlapping, 27-residue triple helical segments of collagen type II, two CNE-binding sites present in peptides II-1 and II-44 were identified. These peptides lack the major binding site for collagen-binding β(1) integrins, defined by the peptide GFOGER. Peptide II-44 corresponds to a region of collagen known to bind collagenases, discoidin domain receptor 2, SPARC (osteonectin), and fibronectin. In addition to binding fibronectin, peptide II-44 but not II-1 inhibited α(V)β(3)-mediated collagen gel contraction and, when immobilized on plastic, supported adhesion of cells. Reduction of fibronectin expression by siRNA reduced PDGF BB-induced α(V)β(3)-mediated contraction. Reconstitution of collagen types I and II gels in the presence of CNE reduced collagen fibril diameters and fibril melting temperatures. Our data indicate that contraction proceeded through an indirect mechanism involving binding of cell-produced fibronectin to the collagen fibers. Furthermore, our data show that cell-mediated collagen gel contraction does not directly depend on the process of fibril formation.
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