Lookup NU author(s): Dr Peter Bell,
Dr Katarzyna Pirog,
Professor Michael Briggs
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Objective: Mutations in matrilin 3 can result in multiple epiphyseal dysplasia (MED), a disease characterized by delayed and irregular bone growth and early-onset osteoarthritis. Although intracellular retention of the majority of mutant matrilin 3 was previously observed in a murine model of MED caused by a Matn3 V194D mutation, some mutant protein was secreted into the extracellular matrix. Thus, it was proposed that secretion of mutant matrilin 3 may be dependent on the formation of hetero-oligomers with matrilin 1. The aim of this study was to investigate the hypothesis that deletion of matrilin 1 would abolish the formation of matrilin 1/matrilin 3 hetero-oligomers, eliminate the secretion of mutant matrilin 3, and influence disease severity. Methods: Mice with a Matn3 V194D mutation were crossed with Matn1-null mice, generating mice that were homozygous for V194D and null formatrilin 1. This novel mouse was used for in-depth phenotyping, while cartilage and chondrocytes were studied both histochemically and biochemically. Results: Endochondral ossification was not disrupted any further in mice with a double V194D mutation compared with mice with a single mutation. A similar proportion of mutant matrilin 3 was present in the extracellular matrix, and the amount of retained mutant matrilin 3 was not noticeably increased. Retained mutant matrilin 3 formed disulfide-bonded aggregates and caused the co-retention of matrilin 1. Conclusion: We showed that secretion of matrilin 3 V194D mutant protein is not dependent on hetero-oligomerization with matrilin 1, and that the total ablation of matrilin 1 expression has no impact on disease severity in mice with MED. Mutant matrilin 3 oligomers form non-native disulfide-bonded aggregates through the misfolded A domain.
Author(s): Bell PA, Piróg KA, Fresquet M, Thornton DJ, Boot-Handford RP, Briggs MD
Publication type: Article
Publication status: Published
Journal: Arthritis & Rheumatism
Print publication date: 26/04/2012
ISSN (print): 0004-3591
ISSN (electronic): 1529-0131
Publisher: John Wiley & Sons, Inc.
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