H3K27 Methylation and H3S28 Phosphorylation-dependent Transcriptional Regulation by INHAT Subunit SET/TAF-Iβ

Significant progress has been made in understanding the relationship between histone modifications and 'reader' molecules and their effects on transcriptional regulation. A previously identified INHAT complex subunit, SET/TAF-Iβ, binds to histones and inhibits histone acetylation. To investigate the binding specificities of SET/TAF-Iβ to various histone modifications, we employed modified histone tail peptide array analyses. SET/TAF-Iβ strongly recognized PRC2-mediated H3K27me1/2/3; however, the bindings were completely disrupted by H3S28 phosphorylation. We have demonstrated that SET/TAF-Iβ is sequentially recruited to the target gene promoter ATF3 after the PRC2 complex via H3K27me recognition and may offer additive effects in the repression of the target gene.