Project description:Dynamic changes in histone modifications under various physiological cues play important roles in gene transcription and cancer. Identification of new histone marks critical for cancer development is of particular importance. Here we show that, in a glucose-dependent manner, E3 ubiquitin ligase NEDD4 ubiquitinates histone H3 on lysine 23/36/37 residues, which specifically recruits histone acetyltransferase GCN5 for subsequent H3 acetylation. Genome-wide analysis of chromatin immunoprecipitation followed by sequencing reveals that NEDD4 regulates glucose-induced H3 K9 acetylation at transcription starting site and enhancer regions. Integrative analysis of ChIP-seq and microarray data sets also reveals a consistent role of NEDD4 in transcription activation and H3 K9 acetylation in response to glucose. Functionally, we show that NEDD4-mediated H3 ubiquitination, by transcriptionally activating IL1α, IL1β and GCLM, is important for tumour sphere formation. Together, our study reveals the mechanism for glucose-induced transcriptome reprograming and epigenetic regulation in cancer by inducing NEDD4-dependent H3 ubiquitination.
Project description:DNA methylation and histone lysine tri-methylation at H3K27 (H3K27me3) are the two primary epigenetic marks for transcriptional silencing essential for cell fate determination and cell lineage commitment during development1, 2. These two marks are mutually exclusive and target distinct sets of genes in the mammalian genome3. However, whether and how H3K27me3 shapes the DNA methylome remains unknown. Here, we report that the loss of H3K27me3 modification leads to increased DNA methylation at previously marked H3K27me3 sites, revealing that H3K27me3 negatively regulates DNA methylation. Genome-wide analysis of H3 ubiquitination, essential for recruitment and activation of DNA methyltransferase DNMT14, reveals the absence of H3 ubiquitination at H3K27me3 marked nucleosomes. Moreover, loss of H3K27me3 modification induces an increase in H3K18 ubiquitination at the corresponding hypermethylated loci. Importantly, we show that H3K27me3 directly inhibits UHRF1-mediated H3 ubiquitination toward nucleosomes in a defined biochemical assay. Furthermore, UHRF1 is required for the increase in DNA methylation at previously marked H3K27me3 sites in cells with abolished H3K27me3 modification. Taken together, our findings reveal a general mechanism for H3K27me3-mediated shaping of the mammalian DNA methylome via modulation of H3 ubiquitination.
Project description:DNA methylation and histone lysine tri-methylation at H3K27 (H3K27me3) are the two primary epigenetic marks for transcriptional silencing essential for cell fate determination and cell lineage commitment during development1, 2. These two marks are mutually exclusive and target distinct sets of genes in the mammalian genome3. However, whether and how H3K27me3 shapes the DNA methylome remains unknown. Here, we report that the loss of H3K27me3 modification leads to increased DNA methylation at previously marked H3K27me3 sites, revealing that H3K27me3 negatively regulates DNA methylation. Genome-wide analysis of H3 ubiquitination, essential for recruitment and activation of DNA methyltransferase DNMT14, reveals the absence of H3 ubiquitination at H3K27me3 marked nucleosomes. Moreover, loss of H3K27me3 modification induces an increase in H3K18 ubiquitination at the corresponding hypermethylated loci. Importantly, we show that H3K27me3 directly inhibits UHRF1-mediated H3 ubiquitination toward nucleosomes in a defined biochemical assay. Furthermore, UHRF1 is required for the increase in DNA methylation at previously marked H3K27me3 sites in cells with abolished H3K27me3 modification. Taken together, our findings reveal a general mechanism for H3K27me3-mediated shaping of the mammalian DNA methylome via modulation of H3 ubiquitination.
Project description:DNA methylation and histone lysine tri-methylation at H3K27 (H3K27me3) are the two primary epigenetic marks for transcriptional silencing essential for cell fate determination and cell lineage commitment during development1, 2. These two marks are mutually exclusive and target distinct sets of genes in the mammalian genome3. However, whether and how H3K27me3 shapes the DNA methylome remains unknown. Here, we report that the loss of H3K27me3 modification leads to increased DNA methylation at previously marked H3K27me3 sites, revealing that H3K27me3 negatively regulates DNA methylation. Genome-wide analysis of H3 ubiquitination, essential for recruitment and activation of DNA methyltransferase DNMT14, reveals the absence of H3 ubiquitination at H3K27me3 marked nucleosomes. Moreover, loss of H3K27me3 modification induces an increase in H3K18 ubiquitination at the corresponding hypermethylated loci. Importantly, we show that H3K27me3 directly inhibits UHRF1-mediated H3 ubiquitination toward nucleosomes in a defined biochemical assay. Furthermore, UHRF1 is required for the increase in DNA methylation at previously marked H3K27me3 sites in cells with abolished H3K27me3 modification. Taken together, our findings reveal a general mechanism for H3K27me3-mediated shaping of the mammalian DNA methylome via modulation of H3 ubiquitination.
Project description:?-Amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid receptors (AMPARs) are the primary mediators of excitatory synaptic transmission in the brain. Alterations in AMPAR localization and turnover have been considered critical mechanisms underpinning synaptic plasticity and higher brain functions, but the molecular processes that control AMPAR trafficking and stability are still not fully understood. Here, we report that mammalian AMPARs are subject to ubiquitination in neurons and in transfected heterologous cells. Ubiquitination facilitates AMPAR endocytosis, leading to a reduction in AMPAR cell-surface localization and total receptor abundance. Mutation of lysine residues to arginine residues at the glutamate receptor subunit 1 (GluA1) C-terminus dramatically reduces GluA1 ubiquitination and abolishes ubiquitin-dependent GluA1 internalization and degradation, indicating that the lysine residues, particularly K868, are sites of ubiquitination. We also find that the E3 ligase neural precursor cell expressed, developmentally down-regulated 4 (Nedd4) is enriched in synaptosomes and co-localizes and associates with AMPARs in neurons. Nedd4 expression leads to AMPAR ubiquitination, leading to reduced AMPAR surface expression and suppressed excitatory synaptic transmission. Conversely, knockdown of Nedd4 by specific siRNAs abolishes AMPAR ubiquitination. These data indicate that Nedd4 is the E3 ubiquitin ligase responsible for AMPAR ubiquitination, a modification that regulates multiple aspects of AMPAR molecular biology including trafficking, localization and stability.
Project description:Chromatin modification through the covalent modifications of histones play crucial role on establishment and propagation of gene expression pattern. Here we sought a global view of histone H3 modifications (tri-M-K4/27 and di-M-K27/36) and occupancy in Arabidopsis thaliana using ChIP combined with high-density tiling microarrays. In these analyses, we included vip3 mutant plants as well to gain an insight into role of Paf1C in plants. Keywords: ChIP on chip