title: In vivo human Cartilage oligomeric matrix protein (COMP) promoter activity.
abstract: Cartilage oligomeric matrix protein (COMP) is a large extracellular matrix protein whose function is unknown. Mutations in COMP cause pseudoachondroplasia and multiple epiphyseal dysplasia, two skeletal dysplasias which are associated with intracellular retention of COMP in chondrocytes. In contrast, COMP null mice are normal suggesting gene redundancy or that the detrimental effect is associated with mutant COMP rather than the absence of functional COMP. To define the elements that regulate COMP transcription and tissue-specificity, we have evaluated the human COMP promoter driving fusion gene expression in vitro and in vivo. COMP promoter activity is higher in rat chondrosarcoma cells (RCS) than in a fibroblast cell line. In RCS cells, expression of a reporter gene containing 1.7 kb of the human COMP promoter was three-fold higher than all shorter COMP promoter constructs. In transgenic mice, 1.7 kb of the human COMP promoter is active early in development in the limbs, spine, and eye. As development progresses, promoter activity diminishes in the eye and migrates from the center to the ends of the long bones. On the other hand, while 375 bp of the human COMP promoter is sufficient for proper tissue-specific expression, levels are less than those found with the 1.7-COMP promoter. The expression pattern of both promoters recapitulates endogenous cartilage COMP expression in mice. Our findings indicate that the elements required for chondrocyte-specific expression lie within 375 bp of the translational start site, while DNA enhancer elements are located between 1.0 to 1.7 kb.
authors.affiliation: Department of Pediatrics, University of Texas Medical School at Houston, 6431 Fannin, 77030, USA.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Posey
authors.forename: Sherri
authors.initials: S
authors.lastname: Davies
authors.forename: Elise S
authors.initials: ES
authors.lastname: Bales
authors.forename: Richard
authors.initials: R
authors.lastname: Haynes
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Sandell
authors.forename: Jacqueline T
authors.initials: JT
authors.lastname: Hecht
mesh_terms: D000818:Animals; D064236:Cartilage Oligomeric Matrix Protein; D002460:Cell Line; D004622:Embryo, Mammalian / Q000196:embryology / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D064235:Matrilin Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic / Q000235:genetics*; D055758:SOX9 Transcription Factor; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D064236:Cartilage Oligomeric Matrix Protein; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D006609:High Mobility Group Proteins; C577540:Matn1 protein, mouse; D064235:Matrilin Proteins; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; C527933:Sox9 protein, mouse; C577553:TSP5 protein, human; D014157:Transcription Factors