Cloning of a mRNA preferentially expressed in chondrocytes by differential display-PCR from a human chondrocytic cell line that is identical with connective tissue growth factor (CTGF) mRNA.

Chondrocyte- or chondrosarcoma cell line (HCS)-specific DNA fragments were obtained using differential display-PCR. Nucleotide sequences of 32 species derived from HCS cells were determined. One of the sequence tags (tag no. 24) corresponded to the nucleotide sequence of connective tissue growth factor (CTGF). Northern blot analysis showed that CTGF was highly expressed in HCS cells and rabbit growth cartilage cells in culture but was not expressed in osteoblastic cells in culture. In situ hybridization revealed that CTGF was expressed only in the hypertrophic chondrocytes of costal cartilage and the vertebral column in embryonic mice. The expression of CTGF in HCS cells was up-regulated by the addition of TGF-beta or BMP-2. These findings suggest that CTGF participates in endochondral ossification.