Activator protein-1 DNA binding activation by hydrogen peroxide in neuronal and astrocytic primary cultures of trisomy-16 and diploid mice

The effect of H2O2 on DNA binding activity of activator protein-1 (AP-1) wa s studied by electrophoretic mobility shift assay (EMSA) in cortical primar y cultures of trisomy-16 mice and their diploid littermates. Exposure to 10 mu M H2O2 for 15 min elicited a greater and earlier occurring increase of AP-1 DNA binding in neuronal primary cultures of trisomy-16 mice than of di ploid mice. When astrocyte-rich primary cultures were exposed to 10 mu M H2 O2 a two-fold increase of AP-1 DNA binding activity was found in trisomy-16 and diploid mice. Supershift EMSA analysis revealed that c-jun was a compo nent of AP-1 in neuronal and glial cultures of diploid and trisomic mice. A 15-min exposure to 10 mu M H2O2 increased c-jun mRNA in cortical neuronal cultures by six-fold, compared with a two-fold increase in cultured astrocy tes. The results documented that H2O2-elicited activation of AP-1 DNA bindi ng in trisomy-16 primary cultures is transcriptionally regulated. Since oxi dative stress also activates various stress-inducible protein kinases that may phosphorylate AP-1 dimers, the increase of AP-1 DNA binding may, in par t, be triggered by phosphorylation. (C) 1999 Published by Elsevier Science B.V. All rights reserved.