FIGURE 6.

A working model on transcriptional repression by PHF2. PHF2 and PHF8 compete for binding of H3K4me3 mark. The binding of PHF8 enhances rDNA transcription in part by promoting the recruitment of UBF. The binding of PHF2 to the H3K4me3 in the rDNA promoter inhibits the binding of PHF8 to the same H3K4me3 mark, which results in reduced binding of UBF. PHF2 also recruits SUV39H1 to rDNA promoter. These two mechanisms are likely to work together to repress rDNA transcription. The same mechanisms may also apply to repression of Pol II target genes by PHF2. H3K4me3 and H3K9me3 are illustrated in short green and black lines, respectively, and the H3 tail is shown by a long blue line. Ac, acetylation. Me, methylation.