OBJECTIVE

To elucidate the effects of resistin on human articular chondrocytes and to generate a picture of their regulation at the transcriptional and posttranscriptional levels.

METHODS

Human articular chondrocytes were cultured with resistin. Changes in gene expression were analyzed at various doses and times. Cells were also treated with the transcription inhibitor actinomycin D after resistin treatment or with the NF-kappaB inhibitor IKK-NBD before resistin treatment. Gene expression was tested by quantitative real-time polymerase chain reaction. Computational analysis for transcription factor binding motifs was performed on the promoter regions of differentially expressed genes. TC-28 chondrocytes were transfected with CCL3 and CCL4 promoter constructs, pNF-kappaB reporter, and NF-kappaB and CCAAT/enhancer binding protein beta (C/EBPbeta) expression vectors with or without resistin.

RESULTS

Resistin-treated human articular chondrocytes increased the expression of cytokines and chemokines. Levels of messenger RNA (mRNA) for matrix metalloproteinase 1 (MMP-1), MMP-13, and ADAMTS-4 also increased, while type II collagen alpha1 (COL2A1) and aggrecan were down-regulated. The cytokine and chemokine genes could be categorized into 3 groups according to the pattern of mRNA expression over a 24-hour time course. One pattern suggested rapid regulation by mRNA stability. The second and third patterns were consistent with transcriptional regulation. Computational analysis suggested the transcription factors NF-kappaB and C/EBPbeta were involved in the resistin-induced up-regulation. This prediction was confirmed by the cotransfection of NF-kappaB and C/EBPbeta and the IKK-NBD inhibition.

CONCLUSION

Resistin has diverse effects on gene expression in human chondrocytes, affecting chemokines, cytokines, and matrix genes. Messenger RNA stabilization and transcriptional up-regulation are involved in resistin-induced gene expression in human chondrocytes.