A comprehensive mRNA expression analysis of developing chicken articular cartilage

• Molecular nature of articular cartilage is conserved among vertebrates.
• Systematic analysis for 36 articular cartilage specific genes provided.
• 17 novel chick articular cartilage specific genes identified.
• Markers specific to outer chondrogenous layer (OCL) and intermediate lamina (IL) of interzone.

Articular cartilage present at the ends of appendicular skeletal elements provides friction-less movement to the synovial joints and any damage to this tissue can lead to a degenerative disease of joint called osteoarthritis. During past two decades although many genes e.g.,Gdf5, Wnt9a, Noggin etc. have been identified and characterized in joint development, still a comprehensive understanding of molecular network(s) operational in articular cartilage morphogenesis is far from being drawn. Here we report identification of 36 genes (19 from literature survey and 17 from microarray analysis) that are expressed in developing chicken phalangeal joints in a spatiotemporally dynamic manner. For both these set of genes across the time window investigated we observed three kinds of expression patterns: early, late and constant. The early expressed genes are invariably expressed in a domain broader than the interzone while the late expressed genes are expressed in restricted spatial domains. The comprehensive expression analysis presented in this report provides a candidate list of molecular players involved in articular cartilage differentiation and/or maintenance.