The large majority of ΔFosB-bound genes identified here appear to be bona fide targets, since levels of their mRNA’s are significantly regulated after inducible overexpression of ΔFosB or its dominant-negative ΔcJun in the NAc (Fig. 2C), which provides important validation of our ChIP-chip data. Interestingly, increased binding of ΔFosB to gene promoters is associated with either increased or decreased mRNA expression, consistent with its complex role as both a transcriptional activator and repressor depending on the gene in question (McClung and Nestler, 2003; Renthal et al., 2008).
