Di Zhang

Peking University Health Science Center, Beijing, Beijing Shi, China

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Publications (6)41.86 Total impact

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    ABSTRACT: Faithful repair of DNA double-strand breaks is vital to the maintenance of genome integrity and proper cell functions. Histone modifications, such as reversible acetylation, phosphorylation, methylation, and ubiquitination, which collectively contribute to the establishment of distinct chromatin states, play important roles in the recruitment of repair factors to the sites of double-strand breaks. Here we report that histone acetyltransferase 1 (HAT1), a classical B type histone acetyltransferase responsible for acetylating the N-terminal tail of newly synthesized histone H4 in the cytoplasm, is a key regulator of DNA repair by homologous recombination in the nucleus. We found that HAT1 is required for the incorporation of H4K5/K12 acetylated H3.3 at sites of double-strand breaks through its HIRA-dependent histone turnover activity. Incorporated histones with specific chemical modifications facilitate subsequent recruitment of RAD51, a key repair factor in mammalian cells, to promote efficient homologous recombination. Significantly, depletion of HAT1 sensitized cells to DNA damage, compromised the global chromatin structure, inhibited cell proliferation, and induced cell apoptosis. Our experiments uncovered a role for HAT1 in DNA repair in higher eukaryotic organisms and provide a mechanistic insight into the regulation of histone dynamics by HAT1.
    Journal of Biological Chemistry 05/2013; · 4.65 Impact Factor
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    ABSTRACT: Polycomb group proteins play essential roles in transcriptional regulation of multiple gene families involved in various pathophysiological processes. It is believed that Polycomb Repressive Complex 2 (PRC2) is targeted to chromatin by the EED subunit to methylate histone H3 lysine 27 (H3K27), leading to a repressive chromatin state that inhibits gene expression. Here we report that the chromodomain-containing protein CDYL specifically recognizes di- and tri-methylated H3K27 (H3K27me2 and H3K27me3) and directly interacts with EZH2, the catalytic subunit of PRC2. We show that CDYL dramatically enhances the methyltransferase activity of PRC2 toward oligonucleosome substrates in vitro. Genome-wide analysis of CDYL targets by ChIP sequencing revealed that CDYL and PRC2 share a number of genomic targets. CDYL is required for chromatin targeting and maximal enzymatic activity of PRC2 at their common target sites. Our experiments indicate that CDYL functions as a molecular bridge between PRC2 and the repressive chromatin mark H3K27me3, forming a positive feedback loop to facilitate the establishment and propagation of H3K27me3 modifications along the chromatin.
    Journal of Biological Chemistry 12/2011; 286(49):42414-25. · 4.65 Impact Factor
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    ABSTRACT: Histone acetyltransferases (HATs) are an essential regulatory component in chromatin biology. Unlike A-type HATs, which are found in the nucleus and utilize nucleosomal histones as substrates and thus primarily function in transcriptional regulation, B-type HATs have been characterized as cytoplasmic enzymes that catalyze the acetylation of free histones. Here, we report on a member of the GCN5-related N-acetyltransferase superfamily and another B-type HAT, HAT4. Interestingly, HAT4 is localized in the Golgi apparatus and displays a substrate preference for lysine residues of free histone H4, including H4K79 and H4K91, that reside in the globular domain of H4. Significantly, HAT4 depletion impaired nucleosome assembly, inhibited cell proliferation, sensitized cells to DNA damage, and induced cell apoptosis. Our data indicate that HAT4 is an important player in the organization and function of the genome and may contribute to the diversity and complexity of higher eukaryotic organisms.
    Molecular cell 10/2011; 44(1):39-50. · 14.61 Impact Factor
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    ABSTRACT: JARID1B is a member of the JmjC/ARID family of demethylases that specifically demethylates tri- and di-methylated forms of histone H3 lysine 4 (H3K4) that are associated with active genes. JARID1B expression is dysregulated in several cancers in which it has been implicated, but how it might affect tumor progression is unclear. In this study, we report that JARID1B is a physical component of the LSD1/NuRD complex that functions in transcriptional repression. JARID1B and LSD1 acted in a sequential and coordinated manner to demethylate H3K4. A genome-wide transcriptional analysis revealed that among the cellular signaling pathways targeted by the JARID1B/LSD1/NuRD complex is the CCL14 chemokine pathway of cell migration and angiogenesis. JARID1B repressed the expression of CCL14, an epithelial derived chemokine, suppressing the angiogenic and metastatic potential of breast cancer cells in vivo. Our findings indicate that CCL14 is a critical mediator of the JARID1B/LSD1/NuRD complex in regulation of angiogenesis and metastasis in breast cancer, identifying a novel potential therapeutic target for breast cancer intervention.
    Cancer Research 09/2011; 71(21):6899-908. · 8.65 Impact Factor
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    ABSTRACT: Transcription activation by estrogen receptor (ER) is rapid and dynamic. How the prompt and precise ER response is established and maintained is still not fully understood. Here, we report that two boundary elements surrounding the well defined ERalpha target TFF1 locus are occupied by the CCCTC-binding factor (CTCF). These elements are separated by 40 kb but cluster in the nuclear space depending on CTCF but independent of estrogen and transcription. In contrast, in estrogen non-responsive breast cancer cells, the spatial proximity of these two elements is lost and the entire locus instead displays a polycomb repressive complex 2-controlled heterochromatin characteristic. We showed that CTCF acts upstream of the "pioneer" factor FOXA1 in determining the genomic response to estrogen. We propose that the CTCF-bound boundary elements demarcate active versus inactive regions, building a framework of adjacent chromosome territory that predisposes ERalpha-regulated transcription.
    Journal of Biological Chemistry 09/2010; 285(37):28604-13. · 4.65 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Transcription activation by estrogen receptor (ER) is rapid and dynamic. How the prompt and precise ER response is established and maintained is still not fully understood. Here, we report that two boundary elements surrounding the well defined ERα target TFF1 locus are occupied by the CCCTC-binding factor (CTCF). These elements are separated by 40 kb but cluster in the nuclear space depending on CTCF but independent of estrogen and transcription. In contrast, in estrogen non-responsive breast cancer cells, the spatial proximity of these two elements is lost and the entire locus instead displays a polycomb repressive complex 2-controlled heterochromatin characteristic. We showed that CTCF acts upstream of the “pioneer” factor FOXA1 in determining the genomic response to estrogen. We propose that the CTCF-bound boundary elements demarcate active versus inactive regions, building a framework of adjacent chromosome territory that predisposes ERα-regulated transcription.
    Journal of Biological Chemistry 09/2010; 285(37):28604-28613. · 4.65 Impact Factor