Up-regulation of cartilage oligomeric matrix protein gene expression by insulin-like growth factor-I revealed by real-time reverse transcription-polymerase chain reaction.
Cartilage oligomeric matrix protein (COMP) strengthens cartilage by binding to type II and type IX collagen-forming bridges between collagen fibrils. It was hypothesized that perhaps one or more anabolic growth factors such as insulin-like growth factor-I (IGF-I), fibroblast growth factor-1 (FGF-1) or platelet derived growth factor-BB (PDGF-BB) increase COMP gene expression. Their effects on primary human chondrocytes and the chondrogenic cell line ATDC5 were studied using real time reverse transcript-polymerase chain reaction (RT-PCR) for quantification. IGF-I, but not the FGF-1 or PDGF-BB, up-regulated COMP gene expression by approximate 5-fold in human adult chondrocytes in a dose- and time-dependent manner. IGF-I exerted similar effects on ATDC5 cells. Results from these real time RT-PCR experiments were confirmed by transfecting into ATDC5 cells a full-length mouse COMP promoter cloned upstream of a luciferase reporter gene. On stimulation with IGF-I, the luciferase reporter activity increased by about eight times. In conclusion, IGF-I seems to be an important positive regulator of COMP, which may play an important role in an attempted repair of either traumatized or degenerated cartilage.
Tian
Hua
H
Department of Orthopaedics, Peking University Third Hospital, Beijing 100083, China. tianhua@medmail.com.cn
Stogiannidis
Ioannis
I
D002356:Cartilage / Q000378:metabolism; D064236:Cartilage Oligomeric Matrix Protein; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis / Q000235:genetics*; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D064235:Matrilin Proteins; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000502:physiology*
D064236:Cartilage Oligomeric Matrix Protein; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C577540:Matn1 protein, mouse; D064235:Matrilin Proteins; D012333:RNA, Messenger; C577553:TSP5 protein, human; D007334:Insulin-Like Growth Factor I