title: Microarray analyses of gene expression during chondrocyte differentiation identifies novel regulators of hypertrophy.
abstract: Ordered chondrocyte differentiation and maturation is required for normal skeletal development, but the intracellular pathways regulating this process remain largely unclear. We used Affymetrix microarrays to examine temporal gene expression patterns during chondrogenic differentiation in a mouse micromass culture system. Robust normalization of the data identified 3300 differentially expressed probe sets, which corresponds to 1772, 481, and 249 probe sets exhibiting minimum 2-, 5-, and 10-fold changes over the time period, respectively. GeneOntology annotations for molecular function show changes in the expression of molecules involved in transcriptional regulation and signal transduction among others. The expression of identified markers was confirmed by RT-PCR, and cluster analysis revealed groups of coexpressed transcripts. One gene that was up-regulated at later stages of chondrocyte differentiation was Rgs2. Overexpression of Rgs2 in the chondrogenic cell line ATDC5 resulted in accelerated hypertrophic differentiation, thus providing functional validation of microarray data. Collectively, these analyses provide novel information on the temporal expression of molecules regulating endochondral bone development.
authors.affiliation: CIHR Group in Skeletal Development and Remodeling, University of Western Ontario, London, Ontario N6A 5C1, Canada.
authors.forename: Claudine G
authors.initials: CG
authors.lastname: James
authors.forename: C Thomas G
authors.initials: CT
authors.lastname: Appleton
authors.forename: Veronica
authors.initials: V
authors.lastname: Ulici
authors.forename: T Michael
authors.initials: TM
authors.lastname: Underhill
authors.forename: Frank
authors.initials: F
authors.lastname: Beier
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D020219:Chondrogenesis / Q000235:genetics*; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D006984:Hypertrophy; D051379:Mice; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010012:Osteogenesis; D020710:RGS Proteins / Q000378:metabolism / Q000502:physiology; D014162:Transfection
chemical_list: D020710:RGS Proteins; C105345:Rgs2 protein, mouse