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A novel form of chondrocyte stress is triggered by a COMP mutation causing pseudoachondroplasia
Author(s) -
Suleman Farhana,
Gualeni Benedetta,
Gregson Hannah J.,
Leighton Matthew P.,
Piróg Katarzyna A.,
Edwards Sarah,
Holden Paul,
BootHandford Raymond P.,
Briggs Michael D.
Publication year - 2012
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.21631
Subject(s) - cartilage oligomeric matrix protein , chondrocyte , unfolded protein response , biology , mutant , microbiology and biotechnology , genetics , endoplasmic reticulum , pathology , gene , medicine , osteoarthritis , in vitro , alternative medicine
Pseudoachondroplasia (PSACH) results from mutations in cartilage oligomeric matrix protein (COMP) and the p.D469del mutation within the type III repeats of COMP accounts for approximately 30% of PSACH. To determine disease mechanisms of PSACH in vivo, we introduced the Comp D469del mutation into the mouse genome. Mutant animals were normal at birth but grew slower than their wild‐type littermates and developed short‐limb dwarfism. In the growth plates of mutant mice chondrocyte columns were reduced in number and poorly organized, while mutant COMP was retained within the endoplasmic reticulum (ER) of cells. Chondrocyte proliferation was reduced and apoptosis was both increased and spatially dysregulated. Previous studies on COMP mutations have shown mutant COMP is co‐localized with chaperone proteins, and we have reported an unfolded protein response (UPR) in mouse models of PSACH‐MED (multiple epiphyseal dysplasia) harboring mutations in Comp (T585M) and Matn3, Comp etc (V194D). However, we found no evidence of UPR in this mouse model of PSACH. In contrast, microarray analysis identified expression changes in groups of genes implicated in oxidative stress, cell cycle regulation, and apoptosis, which is consistent with the chondrocyte pathology. Overall, these data suggest that a novel form of chondrocyte stress triggered by the expression of mutant COMP is central to the pathogenesis of PSACH. Hum Mutat 33:218–231, 2012. © 2011 Wiley Periodicals, Inc.