Pseudoachondroplasia is caused through both intra- and extracellular pathogenic pathways
Robert Dinser1, Frank Zaucke, Florian Kreppel
1Institute for Biochemistry II, University of Cologne, Cologne, Germany. robert.dinser@uniklinik-saarland.de
The Journal of Clinical Investigation
|August 22, 2002
Summary
Pseudoachondroplasia, a rare genetic disorder, is caused by mutations in cartilage oligomeric matrix protein (COMP). Mutant COMP disrupts cell viability and extracellular matrix formation, suggesting it
Area of Science:
- Genetics
- Cell Biology
- Biochemistry
Background:
- Pseudoachondroplasia is a rare, dominantly inherited skeletal dysplasia.
- Mutations in cartilage oligomeric matrix protein (COMP) are linked to pseudoachondroplasia.
- Understanding pseudoachondroplasia pathogenesis is challenging due to its rarity.
Purpose of the Study:
- To develop a cell culture model for pseudoachondroplasia.
- To investigate the intra- and extracellular pathogenic mechanisms of mutant COMP.
- To elucidate the cellular basis of growth failure in pseudoachondroplasia.
Main Methods:
- Expression of mutant COMP in bovine primary chondrocytes using a gutless adenoviral vector.
- Assessment of cellular viability and COMP secretion.
- Analysis of extracellular matrix (ECM) composition and structure.
Main Results:
- Overexpression of mutant COMP decreased chondrocyte viability in a dose-dependent manner.
- Mutant COMP secretion was delayed, indicating endoplasmic reticulum (ER) stress.
- The ECM exhibited disorganized collagen fibers and amorphous aggregates of mutant COMP.
Conclusions:
- Pseudoachondroplasia may be an ER storage disease resulting from misfolded mutant COMP.
- Increased growth-plate chondrocyte death likely explains patient growth failure.
- Mutant COMP interferes with collagen assembly, impairing cartilage and tendon ECM.
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