A cDNA cloning of human AEBP1 from primary cultured osteoblasts and its expression in a differentiating osteoblastic cell line.

By comparing lists of 3'-directed partial cDNA sequences (gene signatures) randomly collected from various tissues, genes uniquely expressed in individual tissue can be identified. A full length cDNA clone, corresponding to one such gene signature, unique to human osteoblast and adipose tissue, was isolated. This cDNA clone encodes a 845-amino acid protein that is almost identical to the mouse adipocyte transcription factor AEBP1 except that it has additional 105 amino acids in the N terminus. A northern hybridization showed that in the differentiating murine osteoblastic cell line, AEBP1 is also expressed but that it is shut off in the final calcification phase, suggesting a transcriptional repressive effect on genes for bone formation.