Transcriptional induction of connective tissue growth factor/hypertrophic chondrocyte-specific 24 gene by dexamethasone in human chondrocytic cells.
Connective tissue growth factor (CTGF/Hcs24) is a critical growth factor for chondrocytic growth and differentiation. In this report, we describe for the first time glucocorticoid-mediated induction of the CTGF/Hcs24 gene in a chondrocytic cell line, HCS-2/8. Steady-state mRNA levels of CTGF/Hcs24 were remarkably increased after treatment with 50 nM dexamethasone, as confirmed by Northern blotting and quantitative real-time polymerase chain reaction (PCR) analysis. Corresponding to the increase in mRNA, production of CTGF/Hcs24 protein was remarkably enhanced, following a time course of up to 6 h. The observed increase in mRNA can be ascribed to transcriptional enhancement, since the stability of CTGF/Hcs24 mRNA was not affected by the same concentration of dexamethasone, which was indicated by the results of an mRNA degradation assay. However, unexpectedly, the prototypic ctgf/hcs24 promoter was not responsible for the dexamethasone stimulation, suggesting the glucocorticoid receptor binding site(s) to be elsewhere in the CTGF/Hcs24 gene. Enhancement of the prototypic promoter activity by dexamethasone was observed in murine fibroblastic cells, demonstrating the complexity of the regulatory mechanism of ctgf/hcs24 gene expression. Of importance, dexamethasone at the same concentration significantly stimulated proteoglycan synthesis in HCS-2/8 cells up to the same levels as exogenously added CTGF/Hcs24. These findings represent a novel effect of glucocorticoid on the production of CTGF/Hcs24 by chondrocytic cells, and indicate that CTGF/Hcs24 may mediate the stimulative effect of dexamethasone on chondrocytic phenotypes. Also, our results shed light on the complex mechanism of CTGF/Hcs24 induction by glucocorticoids.
Kubota
Satoshi
S
Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan.
Moritani
Norifumi H
NH
Kawaki
Harumi
H
Mimura
Haruyo
H
Minato
Masanao
M
Takigawa
Masaharu
M
D020413:3' Untranslated Regions; D002460:Cell Line; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism*; D055513:Connective Tissue Growth Factor; D003907:Dexamethasone / Q000494:pharmacology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D020413:3' Untranslated Regions; C526317:CCN2 protein, human; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D055513:Connective Tissue Growth Factor; D003907:Dexamethasone