title: Gene expression profiling reveals similarities between the spatial architectures of postnatal articular and growth plate cartilage.
abstract: Articular and growth plate cartilage are discrete tissues but arise from a common cartilaginous condensation and have comparable spatial architectures consisting of distinct layers of chondrocytes. To investigate similarities and differences between articular and growth plate cartilage and to explore transcriptional changes that occur during the onset of their divergence, we performed manual microdissection of 10-day-old rat proximal tibias, microarray analysis, bioinformatics, and real-time PCR to compare gene expression profiles in individual cartilage layers. We found that many genes that were spatially upregulated in the intermediate/deep zone of articular cartilage were also spatially upregulated in the resting zone of growth plate cartilage (overlap greater than expected by chance, P<0.001). Interestingly, the superficial zone of articular cartilage showed an expression profile with similarities to both the proliferative and hypertrophic zones of growth plate cartilage (P<0.001 each). Additionally, significant numbers of known proliferative zone markers (3 out of 6) and hypertrophic zone markers (27 out of 126) were spatially upregulated in the superficial zone (more than expected by chance, P<0.001 each). In conclusion, we provide evidence that the intermediate/deep zone of articular cartilage has a gene expression profile more similar to that of the resting zone of growth plate cartilage, whereas the superficial zone has a gene expression profile more similar to those of the proliferative and hypertrophic zones. These findings suggest that the superficial zone chondrocytes of articular cartilage differentiate according to a program that is not completely different from but instead has distinct similarities to the hypertrophic differentiation program of growth plate chondrocytes. We also present functional signaling pathways implicated by differential gene expression between articular and growth plate cartilage during their initial separation by the secondary ossification center.
authors: Pediatric Endocrinology Unit, Department of Women's and Children's Health, Karolinska Institutet and University Hospital, Stockholm, Sweden; Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Michael
authors: M
authors: Chau
authors: Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Julian C
authors: JC
authors: Lui
authors: Pediatric Endocrinology Unit, Department of Women's and Children's Health, Karolinska Institutet and University Hospital, Stockholm, Sweden; Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Ellie B M
authors: EB
authors: Landman
authors: Pediatric Endocrinology Unit, Department of Women's and Children's Health, Karolinska Institutet and University Hospital, Stockholm, Sweden; Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Stephan-Stanislaw
authors: SS
authors: Späth
authors: Department of Developmental Biology, Faculty of Biology and Centre for Medical Biotechnology, University Duisburg-Essen, Essen, Germany.
authors: Andrea
authors: A
authors: Vortkamp
authors: Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Jeffrey
authors: J
authors: Baron
authors: Pediatric Endocrinology Unit, Department of Women's and Children's Health, Karolinska Institutet and University Hospital, Stockholm, Sweden; Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Ola
authors: O
authors: Nilsson
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D016000:Cluster Analysis; D019295:Computational Biology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006132:Growth Plate / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D051381:Rats; D015203:Reproducibility of Results; D015398:Signal Transduction; D059467:Transcriptome