Transcriptional profiling of chondrodysplasia growth plate cartilage reveals adaptive ER-stress networks that allow survival but disrupt hypertrophy

• Published in: PloS one Vol. 6; no. 9; p. e24600
• Main Authors: Cameron, Trevor L, Bell, Katrina M, Tatarczuch, Liliana, Mackie, Eleanor J, Rajpar, M Helen, McDermott, Ben T, Boot-Handford, Raymond P, Bateman, John F
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 15.09.2011; Public Library of Science (PLoS)
• Subjects: Activation; Analysis; Angiogenesis; Animals; Antigens, Neoplasm - genetics; Antigens, Neoplasm - metabolism; Apoptosis; Apoptosis - physiology; Arthritis; Bayesian analysis; Biological activity; Biology; Blotting, Western; Cartilage; Cartilage - cytology; Cartilage - metabolism; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Cell Hypoxia - physiology; Chaperones; Chondrocytes; Chondrocytes - metabolism; Chondrocytes - pathology; Chondrodystrophy; Chondrogenesis; Collagen; Collagen (type X); Computational Biology; Diabetes; Disease; Disruption; Endoplasmic reticulum; Endoplasmic Reticulum Stress - physiology; Extracellular matrix; Extracellular Matrix Proteins - genetics; Extracellular Matrix Proteins - metabolism; Fibroblast growth factors; Fibroblast Growth Factors - genetics; Fibroblast Growth Factors - metabolism; Gene expression; Gene Expression Profiling - methods; Genes; Genetic aspects; Growth; Growth plate; Growth Plate - cytology; Growth Plate - metabolism; Histopathology; Hypertrophy; In Situ Hybridization; In Situ Nick-End Labeling; Kinases; Life sciences; Machinery and equipment; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mice; Microdissection; Microscopy, Electron, Transmission; Mutation; Nerve Growth Factors - genetics; Nerve Growth Factors - metabolism; Networks; Oligonucleotide Array Sequence Analysis; Osteochondrodysplasias - pathology; Pathology; Polymerase Chain Reaction; Protein folding; Proteins; Regulators; Rodents; Signaling; Stress; Stress response; Stresses; Survival; Thyroglobulin; Transcription; Transcription (Genetics); Transcription factors; Vascular endothelial growth factor; Australia; Victoria Australia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0024600

Metaphyseal chondrodysplasia, Schmid type (MCDS) is characterized by mild short stature and growth plate hypertrophic zone expansion, and caused by collagen X mutations. We recently demonstrated the central importance of ER stress in the pathology of MCDS by recapitulating the disease phenotype by expressing misfolding forms of collagen X (Schmid) or thyroglobulin (Cog) in the hypertrophic zone. Here we characterize the Schmid and Cog ER stress signaling networks by transcriptional profiling of microdissected mutant and wildtype hypertrophic zones. Both models displayed similar unfolded protein responses (UPRs), involving activation of canonical ER stress sensors and upregulation of their downstream targets, including molecular chaperones, foldases, and ER-associated degradation machinery. Also upregulated were the emerging UPR regulators Wfs1 and Syvn1, recently identified UPR components including Armet and Creld2, and genes not previously implicated in ER stress such as Steap1 and Fgf21. Despite upregulation of the Chop/Cebpb pathway, apoptosis was not increased in mutant hypertrophic zones. Ultrastructural analysis of mutant growth plates revealed ER stress and disrupted chondrocyte maturation throughout mutant hypertrophic zones. This disruption was defined by profiling the expression of wildtype growth plate zone gene signatures in the mutant hypertrophic zones. Hypertrophic zone gene upregulation and proliferative zone gene downregulation were both inhibited in Schmid hypertrophic zones, resulting in the persistence of a proliferative chondrocyte-like expression profile in ER-stressed Schmid chondrocytes. Our findings provide a transcriptional map of two chondrocyte UPR gene networks in vivo, and define the consequences of UPR activation for the adaptation, differentiation, and survival of chondrocytes experiencing ER stress during hypertrophy. Thus they provide important insights into ER stress signaling and its impact on cartilage pathophysiology.