<正> Cartilage oligomeric matrix protein (COMP) strengthens cartilage by binding to type Ⅱ and typeⅨ collagen-forming bridges between collagen fibrils.It was hypothesized that perhaps one or more anabolicgrowth factors such as insulin-like growth factor-Ⅰ (IGF-Ⅰ),fibroblast growth factor-1 (FGF-1) or plateletderived growth factor-BB (PDGF-BB) increase COMP gene expression.Their effects on primary humanchondrocytes and the chondrogenic cell line ATDC5 were studied using real time reverse transcript-poly-merase chain reaction (RT-PCR) for quantification.IGF-Ⅰ,but not the FGF-1 or PDGF-BB,up-regulatedCOMP gene expression by approximate 5-fold in human adult chondrocytes in a dose-and time-dependentmanner.IGF-Ⅰ exerted similar effects on ATDC5 cells.Results from these real time RT-PCR experimentswere confirmed by transfecting into ATDC5 cells a full-length mouse COMP promoter cloned upstream of aluciferase reporter gene.On stimulation with IGF-Ⅰ,the luciferase reporter activity increased by about eighttimes.In conclusion,IGF-Ⅰ seems to be an important positive regulator of COMP,which may play animportant role in an attempted repair of either traumatized or degenerated cartilage.
