Redox modulation of AP-2 DNA binding activity in vitro

Abstract

Transcription factor AP-2 plays a critical role in regulating gene expression during vertebrate development and cellular differentiation. We report here that AP-2 DNA binding in vitro can be reversibly modulated by redox conditions and that thioredoxin is a potent stimulator of AP-2 DNA binding. Our studies indicate that oxidation of recombinant human AP-2 with diamide or hydrogen peroxide inhibits its DNA binding activity to synthetic AP-2 oligodeoxynucleotides. The inhibitory effect of diamide on AP-2 DNA binding was dose-dependent and was reversible by addition of reducing agents β-mercaptoethanol, dithiothreitol, and thioredoxin. Immunoblot assays indicated that treatment with oxidants caused a change in migration of the AP-2 protein in nonreducing gels and that this effect was also reversible by treatment of the oxidized AP-2 with reducing agents. These data suggest a mechanism by which the oxidation state of conserved cysteine residues in the AP-2 DNA binding domain may contribute to its DNA binding activity. AP-2 joins a group of other transcription factors whose functions are regulated in part by their redox states.