FIGURE 7.

Model for transcriptional activation of the RGS4 gene promoter. The transcriptional state of the RGS4 promoter is controlled by interactions of three transcription factors with two phylogenetically conserved cis-elements in the RGS4 promoter, i.e. binding of transcriptional activators NF-Y and C/EBPβ (with a low affinity, dotted arrow) to the ICE and binding of transcriptional repressor Bcl6 to the Bcl6 element. Activation of RGS4 transcription in confluent PC6 cells is mediated by increases in levels of NF-YA and C/EBPβ LAP and their binding to the ICE and decreases in the level of Bcl6 and its binding to the Bcl6 element. Under these same conditions, acetylation of NF-YA and Bcl6 occurs, leading to increases in NF-YA stability and binding to the ICE and a reduction in binding of Bcl6 to the Bcl6 element.