Edited by Angel NebredaKeywords: G9a p21 Transcription Apoptosis Etoposide a b s t r a c tWe report that H3K9 HMTase G9a activates transcription of the cell cycle regulatory gene, p21, in p53-null H1299 cells. Positive regulation of p21 by G9a is independent of its HMTase activity. We demonstrate that G9a upregulates p21 via interaction with PCAF, and provide evidence that the activating complex is recruited to the p21 promoter upon DNA damage-inducing agent etoposide treatment. Our study suggests that G9a decreases proliferation and cell viability by increasing the level of p21-mediated apoptosis. Our results suggest that G9a functions as a coactivator for p21 transcription, and directs cells to undergo apoptosis. Structured summary of protein interactions:G9a physically interacts with PCAF by anti tag coimmunoprecipitation (1, 2) G9a physically interacts with PCAF by anti bait coimmunoprecipitation (View interaction)

Edited by Ned ManteiKeywords: SET/TAF-Ib INHAT H3S28 Phosphorylation H3K27me Peptide array a b s t r a c t 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-Ib, binds to histones and inhibits histone acetylation. To investigate the binding specificities of SET/TAF-Ib to various histone modifications, we employed modified histone tail peptide array analyses. SET/TAF-Ib strongly recognized PRC2-mediated H3K27me1/2/3; however, the bindings were completely disrupted by H3S28 phosphorylation. We have demonstrated that SET/TAF-Ib 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.