AKT phosphorylates H3-threonine 45 to facilitate termination of gene transcription in response to DNA damage.
Bottom Line: H3-T45 phosphorylation pattern showed close-resemblance to that of RNA polymerase II C-terminal domain (CTD) serine 2 phosphorylation, which establishes the transcription termination signal.AKT1 was more effective than AKT2 in phosphorylating H3-T45.Our findings suggest that AKT-mediated phosphorylation of H3-T45 regulates the processing of the 3' end of DNA damage-activated genes to facilitate transcriptional termination.
Affiliation: National Creative Research Center for Epigenome Reprogramming Network, Department of Biomedical Sciences, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.Show MeSH
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Mentions: H3-T45 lies in the N-terminus of the first helix of H3 and constitutes the nucleosome entry/exit point. This residue is assumed to have significant function, because it makes contact with genomic DNA (28–30). MCF10A cells were treated with ADR, and genome-wide ChIP-seq was performed with phosphorylated H3-T45 antibody, yielding a set of genes that contained phosphorylated H3-T45 (Supplementary Table S2). In our functional annotation analysis, most phosphorylated H3-T45-positive regions lay in cellular stress-responsive genes (Figure 3A and Supplementary Figure S7); the signal appeared primarily in the 3′ UTR of the gene-coding region (Figure 3B, C and Supplementary Figure S8). The specific pattern of H3-T45 phosphorylation, which centered around the transcription termination site (TTS), resembled that of phosphorylated RNA polymerase II CTD-Ser2 (Pol II-S2)/transcription termination factors (11,31). In comparing ChIP-seq profiles (Supplementary Table S2), we noted that over 67% of H3-T45 phosphorylation overlapped with RNA Pol II-S2 phosphorylation (Figure 3D and E). Housekeeping genes, such as GAPDH and HPRT1, were phosphorylated H3-T45-negative (Figure 3F), with lower RNA Pol II-S2 phosphorylation levels than H3-T45-positive genes (Figure 3E and F; RNA Pol II-S2 scale data ranges are 21 and 19 on CDKN1A and MDM2 versus 7.3 and 2.9 on GAPDH and HPRT1, respectively).
Affiliation: National Creative Research Center for Epigenome Reprogramming Network, Department of Biomedical Sciences, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.