||Adiponectin (AN), an adipocyte-derived biologically active molecule, is abundantly present as a plasma protein, and exhibits various biological functions. Two types of adiponectin receptor (AdipoR1 and AdipoR2) have recently been cloned and found to be expressed ubiquitously. More recently, T-cadherin (CDH13) has been characterized as a novel adiponectin receptor on vascular endothelial cells and smooth muscle. Previously, we demonstrated the gene expressions of the two receptors in osteoblasts and their involvement with osteoblastic differentiation. In this study we investigated effects of adiponectin on gene expression profiles during osteoblast differentiation using DNA microarray analysis, and analyzed exclusively the clusters including adiponectin receptors.
Osteoblastic differentiation of a murine pro-osteoblastic cell line, MC3T3-E1 cells, was induced by differential medium including ascorbic acid and β-glycerophosphate with or without recombinant murine full-length type (AN) and globular type (gAN) adiponectin. Three days after stimulation, RNA was extracted and reverse-transcribed. Gene expression profiles were obtained by DNA microarray analysis, and applied to hierarchical clustering with correlation centered similarity metrics. Functional cluster annotations for the selected clusters were generated based on the significant gene ontology terms.
The significant genes up-regulated by differential medium were related to osteoblast differentiation and cell growth. The cluster AdipoR1 belonged to included the genes which were down-regulated by differential medium, although the cluster AdipoR2 belonged to included the genes up-regulated by the medium. CDH13 was also belonged to the cluster including the genes up-regulated during osteoblastic differentiation.