An inducible cartilage oligomeric matrix protein mouse model recapitulates human pseudoachondroplasia phenotype.

Abstract

Cartilage oligomeric matrix protein (COMP) is a pentameric extracellular protein expressed in cartilage and other musculoskeletal tissues. Mutations in the COMP gene cause pseudoachondroplasia (PSACH), a severe dwarfing condition that has a growth plate chondrocyte pathology. PSACH is characterized by intracellular retention of COMP and other extracellular matrix (ECM) proteins, which form an ordered matrix within large rough endoplasmic reticulum cisternae. This accumulation is cytotoxic and causes premature chondrocyte cell death, thereby depleting chondrocytes needed for normal long bone growth. Research to define the underlying molecular mechanisms of PSACH has been hampered by the lack of a suitable model system. In this study, we achieved robust expression of human mutant (MT) or wild-type (WT) COMP in mice by using a tetracycline-inducible promoter. Normal growth plate distribution of ECM proteins was observed in 1-month-old WT-COMP and C57BL\6 control mice. In contrast, the structure of the MT-COMP growth plate recapitulated the findings of human PSACH growth plate morphology, including (1) retention of ECM proteins, (2) intracellular matrix formation in the rER cisternae, and (3) increased chondrocyte apoptosis. Therefore, we have generated the first mouse model to show extensive intracellular retention of ECM proteins recapitulating the human PSACH disease process at the cellular level.

• Authors: Karen L Posey, Alka C Veerisetty, Pieman Liu, Huiqiu R Wang, Brian J Poindexter, Roger Bick, Joseph L Alcorn, Jacqueline T Hecht
• Journal: The American journal of pathology (Am J Pathol) Vol. 175 Issue 4 Pg. 1555-63 (Oct 2009) ISSN: 1525-2191 [Electronic] United States
• PMID: 19762713 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Cartilage Oligomeric Matrix Protein
• Collagen Type IX
• Extracellular Matrix Proteins
• Glycoproteins
• Matn1 protein, mouse
• Matn3 protein, mouse
• Matrilin Proteins
• TSP5 protein, human

Topics

• Animals
• Apoptosis
• Cartilage Oligomeric Matrix Protein
• Chondrocytes (metabolism, pathology)
• Collagen Type IX (metabolism)
• Disease Models, Animal
• Endoplasmic Reticulum (metabolism)
• Extracellular Matrix Proteins (chemistry, metabolism)
• Glycoproteins (chemistry, metabolism)
• Growth Plate (abnormalities, pathology)
• Humans
• Matrilin Proteins
• Mice
• Mice, Transgenic
• Mutation (genetics)
• Osteochondrodysplasias (pathology)
• Phenotype
• Protein Structure, Quaternary