Microarray Analysis of Gene Expression in CCD Dental Pulp Cells

Runx2 is a transcription factor essential to osteoblast and odontoblast differentiation. Mutations of Runx2 are associated with Cleidocranial Dysplasia (CCD), an autosomal dominant disorder characterized by defective bone and tooth formation. Alteration of gene expression in the CCD dental phenotype remains unknown. Objective: The purpose of this study was to investigate human primary dental pulp cells of a CCD patient versus age and sex matched controls related to: 1) gene expression profiles of downstream target genes of Runx2 by a cDNA microarray technology; 2) rescue of the altered gene expression in CCD cells by overexpression of Runx2 and Osterix. Methods: To determine the effect of Runx2 mutation on the production of target gene expression in the CCD cells, the gene expression profiles of the CCD versus normal dental pulp cells were analyzed using a human cytokine/receptor DNA array. RNA was extracted from the both primary CCD and normal dental pulp cells, converted to 33P-cDNA labeled probes and hybridized to the array. Expression of selected genes was further verified by quantitative real time polymerase chain reaction (qRT-PCR). To rescue the altered gene expression, the CCD cells were transfected with Runx2 and Osterix, respectively. Results: among 226 genes analyzed in cDNA microarray, 25 genes were up-regulated by 2-fold or greater, and 17 genes were down-regulated by 2-fold or greater. Expression of selected genes was further confirmed by qRT-PCR. Overexpression of Runx2 or Osterix gene partially rescues the downstream gene expression of Runx2 in the CCD cells. Conclusion: This study indicates that altered Runx2 gene expression associated with CCD in dental pulp cells alters expression levels of the down-stream genes. The results suggest that such alterations of the gene expression may contribute to the dental phenotype in CCD. This work was supported by NIDCR grant DE P01 DE13221 (M.M.).