ACTIVATION OF TRANSCRIPTION FACTOR AP-1 BY EXTRACELLULAR ATP IN PC12 CELLS

We have previously shown that extracellular ATP caused cell death in P C12 cells through activation of its receptors. Oxidative stress has be en implicated as a mechanism of cell death caused by extracellular ATP . In the present study we examined the possible signal transduction ca scades leading to cell death by extracellular ATP. We found, using the electrophoretic mobility shift assay, that transcription factor AP-I DNA binding activity was stimulated by extracellular ATP. Northern blo t analysis showed that mRNA levels of c-fos, c-jun were elevated after treatment with ATP. The stimulation was receptor mediated, since it w as blocked by the ATP receptor antagonist, suramin. The stimulated AP- 1 binding was also blocked by the antioxidant N-acetyl-L-cysteine, ind icating that reactive oxygen species generated following ATP stimulati on were involved in the induction of AP-1 activity. It appears that bo th translational and posttranslational events contributed to the incre ased AP-1 DNA binding since cyclohexamide (a protein synthesis inhibit or), genistein (tyrosine kinase inhibitor) and staurosporine (PKC inhi bitor) each partially blocked the AP-1 activation. Changes in AP-1 DNA binding activity may modulate expression of target genes involved in cell death pathways.