| 1. |
- Brandau, Oliver, et al.
(författare)
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Chondromodulin I Is Dispensable during Enchondral Ossification and Eye Development.
- 2002
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Ingår i: Molecular and Cellular Biology. - 0270-7306. ; 22:18, s. 6627-6635
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Tidskriftsartikel (refereegranskat)abstract
- Chondromodulin I (chm-I), a type II transmembrane protein, is highly expressed in the avascular zones of cartilage but is downregulated in the hypertrophic region, which is invaded by blood vessels during enchondral ossification. In vitro and in vivo assays with the purified protein have shown chondrocyte-modulating and angiogenesis-inhibiting functions. To investigate chm-I function in vivo, we generated transgenic mice lacking chm-I mRNA and protein. Null mice are viable and fertile and show no morphological changes. No abnormalities in vascular invasion and cartilage development were detectable. No evidence was found for a compensating function of tendin, a recently published homologue highly expressed in tendons and also, at low levels, in cartilage. Furthermore, no differences in the expression of other angiogenic or antiangiogenic factors such as transforming growth factor beta1 (TGF-beta1), TGF-beta2, TGF-beta3, fibroblast growth factor 2, and vascular endothelial growth factor were found. The surprising lack of phenotype in the chm-I-deficient mice suggests either a different function for chm-I in vivo than has been proposed or compensatory changes in uninvestigated angiogenic or angiogenesis-inhibiting factors. Further analysis using double-knockout technology will be necessary to analyze the function of chm-I in the complex process of enchondral ossification.
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| 2. |
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| 3. |
- Moser, Markus, et al.
(författare)
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Ultrastructural cartilage abnormalities in MIA/CD-RAP-deficient mice
- 2002
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Ingår i: Molecular and Cellular Biology. - 0270-7306. ; 22:5, s. 1438-1445
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Tidskriftsartikel (refereegranskat)abstract
- MIA/CD-RAP is a small, soluble protein secreted from malignant melanoma cells and from chondrocytes. Recent evidence has identified MIA/CD-RAP as the prototype of a small family of extracellular proteins adopting an SH3 domain-like fold. It is thought that interaction between MIA/CD-RAP and specific epitopes in extracellular matrix proteins regulates the attachment of tumor cells and chondrocytes. In order to study the consequences of MIA/CD-RAP deficiency in vivo, we generated mice with a targeted gene disruption. The complete absence of MIA/CD-RAP mRNA and protein expression was demonstrated by reverse transcriptase, Western blot analysis, and enzyme-linked immunosorbent assay measurements of whole-embryo extracts. MIA-/- mice were viable and developed normally, and histological examination of the organs by means of light microscopy revealed no major abnormalities. In contrast, electron microscopic studies of cartilage composition revealed subtle defects in collagen fiber density, diameter, and arrangement, as well as changes in the number and morphology of chondrocytic microvilli. Taken together, our data indicate that MIA/CD-RAP is essentially required for formation of the highly ordered ultrastructural fiber architecture in cartilage and may have a role in regulating chondrocyte matrix interactions.
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| 4. |
- Svensson, Liz, et al.
(författare)
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Cartilage oligomeric matrix protein-deficient mice have normal skeletal development.
- 2002
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Ingår i: Molecular and Cellular Biology. - 0270-7306. ; 22:12, s. 4366-4371
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Tidskriftsartikel (refereegranskat)abstract
- Cartilage oligomeric matrix protein (COMP) belongs to the thrombospondin family and is a homopentamer primarily expressed in cartilage. Mutations in the COMP gene result in the autosomal dominant chondrodysplasias pseudoachondroplasia (PSACH) and some types of multiple epiphyseal dysplasia (MED), which are characterized by mild to severe short-limb dwarfism and early-onset osteoarthritis. We have generated COMP-null mice to study the role of COMP in vivo. These mice show no anatomical, histological, or ultrastructural abnormalities and show none of the clinical signs of PSACH or MED. Northern blot analysis and immunohistochemical analysis of cartilage indicate that the lack of COMP is not compensated for by any other member of the thrombospondin family. The results also show that the phenotype in PSACH/MED cartilage disorders is not caused by the reduced amount of COMP.
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