[Effects of bone morphogenetic protein-2 on cartilage oligomeric matrix protein expression in chondrocytes].
OBJECTIVE
To quantitatively evaluate the effects of BMP-2 on the COMP gene expression in both primary human chondrocytes and chondrogenic cell line ATDC55.


METHODS
Human adult and fetal chondrocytes were stimulated by BMP-2. The COMP gene expression level was analyzed by real time reverse transcription-PCR assay and normalized to a reference mRNA (GAPDH). Next, a full-length mCOMP promoter cloned upstream of luciferase reporter gene was transfected into ATDC55 cells and stimulated by 500 micrograms.L-1 BMP-2 in the presence or absence of 10 micrograms.L-1 of Noggin.


RESULTS
We found that BMP-2 up-regulated COMP gene expression by approximate 3 folds in human adult chondrocytes, and 1.5 folds in human fetal chondrocytes. The difference in magnitude of COMP gene stimulation by BMP-2 might attribute to the difference of COMP gene basal expression level in chondrocytes from different sources because it was found that the COMP gene expression was 2 folds higher in quiescent fetal chondrocytes than in adult chondrocytes. For further analysis of the effect of BMP-2 on COMP gene expression by RT-PCR, a rat chondrogenic cell line of ATDC55 cells was used. While no COMP gene expression was detected in unstimulated cells, COMP expression was significantly induced after treatment with BMP-2. This induction could be specifically blocked by 10 micrograms.L-1 of Noggin. It was found that BMP-2 markedly increased the luciferase reporter activity by about 5 folds and again, Noggin specifically blocked the BMP-2 activity.


CONCLUSIONS
BMP-2 up-regulates the COMP gene expression in both primary human chondrocytes and chondrogenic cell line ATDC55.
Tian
Hua
H
Department of Orthopaedics, Peking University Third Hospital, Beijing 100083, China. tianhua68@yahoo.com
Fang
Carrie
C
Dicesare
Paul E
PE
D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D064236:Cartilage Oligomeric Matrix Protein; D002460:Cell Line; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D064235:Matrilin Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta
C525718:BMP2 protein, human; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D064236:Cartilage Oligomeric Matrix Protein; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D064235:Matrilin Proteins; C577553:TSP5 protein, human; D016212:Transforming Growth Factor beta