1. ¹Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
2. ²Department of Oral and Maxillofacial Reconstructive Surgery, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan
3. ³Biosciences Business Division, Nichirei Corporation, Chuo-ku, Tokyo, Japan

Correspondence: Professor M Takigawa, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8525, Japan. E-mail: takigawa@md.okayama-u.ac.jp

Received 21 March 2005; Revised 4 August 2005; Accepted 16 August 2005; Published online 10 October 2005.

Abstract

Connective tissue growth factor (CTGF/CCN2) can be induced by various forms of stress such as exposure to high glucose, mechanical load, or hypoxia. Here, we investigated the molecular mechanism involved in the induction of ctgf/ccn2 by hypoxia in a human chondrosarcoma cell line, HCS-2/8. Hypoxia increased the ctgf/ccn2 mRNA level by altering the 3'-untranslated region (UTR)-mediated mRNA stability without requiring de novo protein synthesis. After a series of extensive analyses, we eventually found that the cis-repressive element of 84 bases within the 3'-UTR specifically bound to a cytoplasmic/nuclear protein. By conducting a UV crosslinking assay, we found the cytoplasmic/nuclear protein to be a 35 kDa molecule that bound to the cis-element in a hypoxia-inducible manner. These results suggest that a cis-element in the 3'-UTR of ctgf/ccn2 mRNA and trans-factor counterpart(s) play an important role in the post-transcriptional regulation by determining the stability of ctgf/ccn2 mRNA.