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Objectives: The level of histone H3 lysine 79 methylation is regulated by the cell cycle and involved in cell proliferation. KDM2B is an H3K79 demethylase. Proliferating cell nuclear antigen (PCNA) is a component of the DNA replication machinery. This study aimed at elucidating a molecular link between H3K79me recognition of PCNA and cell cycle control. Materials and methods: We generated KDM2B‐depleted 293T cells and histone H3‐K79R mutant‐expressing 293T cells. Western blots were primarily utilized to examine the H3K79me level and its effect on subsequent PCNA dissociation from chromatin. We applied IP, peptide pull‐down, isothermal titration calorimetry (ITC) and ChIP experiments to show the PCNA binding towards methylated H3K79 and DNA replication origins. Flow cytometry, MTT, iPOND and DNA fibre assays were used to assess the necessity of KDM2B for DNA replication and cell proliferation. Results: We revealed that KDM2B‐mediated H3K79 demethylation regulated cell cycle progression. We found that PCNA bound chromatin in an H3K79me‐dependent manner during S phase. KDM2B was responsible for the timely dissociation of PCNA from chromatin, allowing to efficient DNA replication. Depletion of KDM2B aberrantly enriched chromatin with PCNA and caused slow dissociation of residual PCNA, leading to a negative effect on cell proliferation. Conclusions: We suggested a novel interaction between PCNA and H3K79me. Thus, our findings provide a new mechanism of KDM2B in regulation of DNA replication and cell proliferation. [ABSTRACT FROM AUTHOR]

Post‐translational modification of forkhead family transcription factor, FoxO1, is an important regulatory mode for its diverse activities. FoxO1 is acetylated by HAT coactivators and its transcriptional activity is decreased via reduced DNA binding affinity. Here, we report that SET/TAF‐Iβ inhibited p300‐mediated FoxO1 acetylation in an INHAT domain‐dependent manner. SET/TAF‐Iβ interacted with FoxO1 and activated transcription of FoxO1 target gene, p21. Moreover, SET/TAF‐Iβ inhibited acetylation of FoxO1 and increased p21 transcription induced by oxidative stress. Our results suggest that SET/TAF‐Iβ inhibits FoxO1 acetylation and activates its transcriptional activity toward p21.SET/TAF‐Iβ inhibits FoxO1 acetylation. SET/TAF‐Iβ interacts with FoxO1 in INHAT domain dependent manner. Recruitment of FoxO1 on p21 promoter is increased by SET/TAF‐Iβ. SET/TAF‐Iβ induces p21 transcription and apoptosis under oxidative stress. [ABSTRACT FROM AUTHOR]

Highlights: [•] G9a upregulates p21 expression independently of its HMTase activity. [•] Positive regulation of p21 by G9a is p53 independent. [•] G9a interacts with PCAF to activate p21 expression. [•] G9a and PCAF are recruited to p21 promoter upon etoposide treatment. [•] G9a inhibits cell survival via p21-mediated apoptosis upon cellular stress. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: The proto-oncogene protein DEK has been implicated in the t(6;9) chromosomal translocation associated with a subtype of acute myelogenous leukemia (AML), which results in the formation of a DEK-CAN fusion protein. Histone acetylation is an important post-translational modification which is involved in transcriptional regulation. In this study, we report that the acidic domain containing protein DEK interacts with histones and exerts a potent inhibitory effect on both p300 and PCAF-mediated histone acetyltransferase activity and transcription. Using chromatin immunoprecipitation assays, we have demonstrated that the recruitment of DEK to the appropriate promoter induces the histone H3 and H4 hypoacetylation of chromatin. Collectively, our data illustrate the important regulatory role played by protein DEK in transcriptional regulation, and suggest that transcription-regulating acidic domain regions may play a role in leukemogenesis. [Copyright &y& Elsevier]