SNP-induced apoptosis may be mediated with caspase inhibitor by JNK signaling pathways in rabbit articular chondrocytes.

NO plays an important role in cartilage destruction by inducing apoptosis of chondrocytes. Here we investigated the role of c-Jun N-terminal kinase (JNK) signal transduction pathways in the apoptosis induced by NO donor sodium nitroprusside (SNP) in rabbit articular chondrocytes. We used Annexin V-FITC/PI flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) assay to detect apoptosis rate. The expressions of p38, NF-κB p65, caspase-3 and p53 genes at protein levels were measured by Western blotting assay. RT-PCR was performed to show the mRNA expression of caspase-3, and the activity of caspase-3 was also detected. To investigate the effect of JNK-specific inhibitor SP600125, chondrocytes were pretreated with SP600125 ahead of SNP treatment. Treatment with SNP accelerated apoptosis in a concentration dependent manner, while such acceleration was reduced by SP600125 pretreatment. Moreover, we found that SP600125 significantly decreased NO-induced NF-κB, p53, caspase-3 protein expressions and caspase-3 mRNA expression, as well as intracellular caspase-3 activity (P < 0.05). Collectively, these data suggest that JNK plays an important role through stimulating NF-κB, p53 and caspase-3 activation.