Coordinate gene expression patterns during osteoblast maturation and retinoic acid treatment of MC3T3-E1 cells

The clonal osteoblast-like cell line MC3T3-E1 undergoes time-dependent morphological changes leading to the formation of bone nodules in vitro. Serial analysis of gene expression was used to identify genes expressed in MC3T3-E1 cells, including known osteoblast markers, structural and matrix proteins, transcription factors, cell-cycle regulators, and housekeeping genes. Relative changes in the expression of 92 representative transcripts were determined by arrayed cDNA hybridization. Complex probes were derived from MC3T3-E1 cells during the proliferation, differentiation, and matrix mineralization stages, and from cells grown with all- trans-retinoic acid (RA), a potent bone morphogen. We found that the relative expression of 68 of these genes was higher during differentiation than in the earlier proliferative phase. In the mineralization phase, all but 16 cDNAs had lower normalized hybridization intensity ratios as compared with the differentiation phase. cDNAs for vimentin (Vim), presenilin 2 (Psen2), guanine nucleotide binding protein alpha stimulating (Gnas), gap-junction membrane channel protein beta 1 (Gjb1), fibroblast growth factor receptor 1 (Fgfr1), eukaryotic translation elongation factor 2 (Eef2), and calponin 2 (Cnn2) had higher normalized hybridization intensities in both differentiation and mineralization than in proliferation. RA treatment during the differentiation phase appeared to reduce the expression of the 92 genes examined, as 62 cDNAs had lower hybridization intensities with complex cDNA probes derived from RA-treated cells than with the probe from untreated cells. Several cDNAs representing genes with previously unrecognized RA responsiveness were identified by this comparison, including the receptor for bone morphogenetic proteins 2 and 4 (Bmp2/Bmp4) and hemoglobin Y.