Project description:The goal of this project is to understand the role of SIRT1, the most conserved mammalian NAD+-dependent protein deacetylase, in methionine metabolism and pluripotency of mESCs. Our recent studies indicate that SIRT1 deficient mESCs are hypersensitive to methionine restriction-induced differentiation and apoptosis, primarily due to a reduced conversion of methionine to S-adenosylmethionine. This reduction leads to marked decrease in methylation levels of histones in SIRT1 deficient mESCs. To understand the impact of histone methylation alterations on stem cell functions in SIRT1 KO mESCs, we examined the transcriptomes of SIRT1 WT and KO mESCs cultured in either complete M10 medium (com) or methionine restricted medium containing 6 uM methionine (6met) for 6, 24, and 72 hours by microarray analysis.
Project description:Epigenetic modifications on DNA and histones regulate gene expression by modulating chromatin accessibility to transcription machinery. Chromatin-modifying enzymes are dependent on metabolic intermediates for chromatin remodeling, linking nutrient availability and cellular metabolism to the cellular epigenetic landscape. Here we identify methionine as a key nutrient affecting T cell epigenetic reprogramming in CD4+ T helper (Th) cells. Using metabolomic approaches, we showed that methionine is rapidly taken up by activated T cells and then serves as the major substrate for the biosynthesis of S-adenosyl-L-methionine (SAM), the universal methyl donor for cellular methyltransferases. Conversely, methionine restriction (MR) depletes intracellular SAM pools, reduces global histone H3K4 methylation (H3K4me3) in T cells, and reduces H3K4me3 levels at the promoter regions of key genes involved in CD4+ Th17 cell proliferation and cytokine production. Applied to the mouse model of multiple sclerosis (experimental autoimmune encephalomyelitis), dietary methionine restriction reduced the expansion of pathogenic Th17 cells in vivo, leading to reduced T cell-mediated neuroinflammation and disease onset. Overall our data identify methionine as a key nutritional factor that shapes T cell proliferation, differentiation, and function in part through regulation of histone methylation in T cells.
Project description:Epigenetic modifications on DNA and histones regulate gene expression by modulating chromatin accessibility to transcription machinery. Chromatin-modifying enzymes are dependent on metabolic intermediates for chromatin remodeling, linking nutrient availability and cellular metabolism to the cellular epigenetic landscape. Here we identify methionine as a key nutrient affecting T cell epigenetic reprogramming in CD4+ T helper (Th) cells. Using metabolomic approaches, we showed that methionine is rapidly taken up by activated T cells and then serves as the major substrate for the biosynthesis of S-adenosyl-L-methionine (SAM), the universal methyl donor for cellular methyltransferases. Conversely, methionine restriction (MR) depletes intracellular SAM pools, reduces global histone H3K4 methylation (H3K4me3) in T cells, and reduces H3K4me3 levels at the promoter regions of key genes involved in CD4+ Th17 cell proliferation and cytokine production. Applied to the mouse model of multiple sclerosis (experimental autoimmune encephalomyelitis), dietary methionine restriction reduced the expansion of pathogenic Th17 cells in vivo, leading to reduced T cell-mediated neuroinflammation and disease onset. Overall our data identify methionine as a key nutritional factor that shapes T cell proliferation, differentiation, and function in part through regulation of histone methylation in T cells.
Project description:Histone H3 lysine27-to-methionine (H3K27M) gain-of-function mutations occur in highly aggressive pediatric gliomas. Here, we establish a Drosophila animal model for the pathogenic histone H3K27M mutation and show that its overexpression resembles Polycomb repressive complex 2 (PRC2) loss-of-function phenotypes, causing de-repression of PRC2 target genes and developmental perturbations. Similarly, a H3K9M mutant depletes H3K9 methylation levels and suppresses position-effect variegation in various Drosophila tissues. The histone H3K9 demethylase KDM3B/JHDM2 associates with H3K9M nucleosomes and its overexpression in Drosophila results in loss of H3K9 methylation levels and heterochromatic silencing defects. Here we establish histone lysine-to-methionine mutants as robust in vivo tools for inhibiting methylation pathways that also function as biochemical reagents for capturing site-specific histone-modifying enzymes, thus providing molecular insight into chromatin-signaling pathways. RNA-seq of wing imaginal discs expressing either H3.3WT-FLAG-HA or H3.3K27M-FLAG-HA.
Project description:Histone modifications are integral to epigenetics through their influence on gene expression and cellular status. While it's established that metabolism, including methionine metabolism, can impact histone methylation, the direct influence of methionine availability on crucial histone marks that determine the epigenomic process remains poorly understood. In this study, we demonstrate that methionine, through its metabolic product, S-adenosylmethionine (SAM), dynamically regulates H3K36me3, a cancer-associated histone modification known to influence cellular status, and myogenic differentiation of mouse myoblast cells. We further demonstrate that the methionine-dependent effects on differentiation are mediated in part through the histone methyltransferase SETD2, which senses methionine levels. Additionally, methionine restriction leads to preferential decreases in H3K36me3 abundance and genome accessibility of genes involved in myogenic differentiation. Importantly, the effects of methionine restriction on differentiation and chromatin accessibility can be phenocopied by the deletion of Setd2. Collectively, this study demonstrates that methionine metabolism through its ability to be sensed by chromatin modifying enzymes can have a direct role in influencing cell fate determination.
Project description:Histone modifications are integral to epigenetics through their influence on gene expression and cellular status. While it's established that metabolism, including methionine metabolism, can impact histone methylation, the direct influence of methionine availability on crucial histone marks that determine the epigenomic process remains poorly understood. In this study, we demonstrate that methionine, through its metabolic product, S-adenosylmethionine (SAM), dynamically regulates H3K36me3, a cancer-associated histone modification known to influence cellular status, and myogenic differentiation of mouse myoblast cells. We further demonstrate that the methionine-dependent effects on differentiation are mediated in part through the histone methyltransferase SETD2, which senses methionine levels. Additionally, methionine restriction leads to preferential decreases in H3K36me3 abundance and genome accessibility of genes involved in myogenic differentiation. Importantly, the effects of methionine restriction on differentiation and chromatin accessibility can be phenocopied by the deletion of Setd2. Collectively, this study demonstrates that methionine metabolism through its ability to be sensed by chromatin modifying enzymes can have a direct role in influencing cell fate determination.
Project description:In our study, deletion of methionine synthesis gene metE (SPD_0510) impaired the growth of Streptococcus pneumoniae strain D39 significantly when bacteria were cultured in chemically defined medium with a low concentration of methionine. Bacteria undergo methionine starvation in this condition. We aimed to know how S. pneumoniae responses to methionine starvation, particularly at the transcriptional level. RNA-seq results show that 804 genes (41.2 % of whole genome) were differentially expressed under methionine starvation. Among them, 258 genes (32.1 %) are related to cell metabolism, with 75 genes involved in sugar and carbon metabolism, 88 genes for synthesis of metabolic products and 95 genes for uptake of amino acids and sugars. Combined with other experiments data, this showed the reprogrammed metabolism in S. pneumoniae under methionine starvation.
Project description:Histone H3 lysine27-to-methionine (H3K27M) gain-of-function mutations occur in highly aggressive pediatric gliomas. Here, we establish a Drosophila animal model for the pathogenic histone H3K27M mutation and show that its overexpression resembles Polycomb repressive complex 2 (PRC2) loss-of-function phenotypes, causing de-repression of PRC2 target genes and developmental perturbations. Similarly, a H3K9M mutant depletes H3K9 methylation levels and suppresses position-effect variegation in various Drosophila tissues. The histone H3K9 demethylase KDM3B/JHDM2 associates with H3K9M nucleosomes and its overexpression in Drosophila results in loss of H3K9 methylation levels and heterochromatic silencing defects. Here we establish histone lysine-to-methionine mutants as robust in vivo tools for inhibiting methylation pathways that also function as biochemical reagents for capturing site-specific histone-modifying enzymes, thus providing molecular insight into chromatin-signaling pathways.