Project description:Human cells can synthesize methionine from homocysteine and folate-coupled methyl groups via the B12-dependent enzyme methionine synthase (MTR). Yet, it has been known for decades that cancer cells fail to grow when methionine is replaced by homocysteine, a phenomenon known as methionine dependence. Here, we report single-cell RNA-sequencing data from MDA-MB-231 breast cancer cells adapted to grow without methionine in the presence of high levels of vitamin B12 for 21 days. Compared to parental cells (D0), the adapted “revertant” cells (D21) display gene expression signatures consistent with reduced invasion and metastasis.
Project description:Targeting altered tumor cell metabolism might provide an attractive opportunity for patients with acute myeloid leukemia (AML). An amino acid dropout screen on primary leukemic stem cells and progenitor populations revealed a number of amino acid dependencies, of which methionine was one of the strongest. By using various metabolite rescue experiments, NMR-based metabolite quantifications and 13C-tracing, polysomal profiling, and ChIP-seq, we identified that methionine is used predominantly for protein translation and to provide methyl groups to histones via S-adenosylmethionine for epigenetic marking. H3K36me3 was consistently the most heavily impacted mark following loss of methionine. Methionine depletion also reduced total RNA levels, enhanced apoptosis and induced a cell cycle block. ROS levels were not increased following methionine depletion and replacement of methionine with glutathione or N-acetylcysteine could not rescue phenotypes, excluding a role for methionine in controlling redox balance control in AML. Although considered to be an essential amino acid, methionine can be recycled from homocysteine. We uncovered that this is primarily performed by the enzyme methionine synthase and only when methionine availability becomes limiting. In vivo, dietary methionine starvation was not only tolerated by mice, but also significantly delayed both cell line and patient-derived AML progression. Finally, we show that inhibition of the H3K36-specific methyltransferase SETD2 phenocopies much of the cytotoxic effects of methionine depletion, providing a more targeted therapeutic approach. In conclusion, we show that methionine depletion is a vulnerability in AML that can be exploited therapeutically, and we provide mechanistic insight into how cells metabolize and recycle methionine.
Project description:In this study, we combined metabolic reconstruction, growth assays, metabolome and transcriptome analyses to obtain a global view of the sulfur metabolic network and of the response to sulfur availability in Brevibacterium aurantiacum. In agreement with the growth of B. aurantiacum in the presence of sulfate and cystine, the metabolic reconstruction showed the presence of a sulfate assimilation pathway and of thiolation pathways that produce cysteine (cysE and cysK) or homocysteine (metX and metY) from sulfide, of at least one gene of the transsulfuration pathway (aecD) and of genes encoding three MetE-type methionine synthases. We also compared the expression profiles of B. aurantiacum ATCC9175 during sulfur starvation and in the presence of sulfate, cystine or methionine plus cystine. In sulfur starvation, 690 genes including 21 genes involved in sulfur metabolism and 29 genes encoding amino acids and peptide transporters were differentially expressed. We also investigated changes in pools of sulfur-containing metabolites and in expression profiles after growth in the presence of sulfate, cystine or methionine plus cystine. The expression of genes involved in sulfate assimilation and cysteine synthesis was repressed in presence of cysteine, while the expression of metX, metY, metE1, metE2 and BL613 encoding a probable cystathionine-γ-synthase decreased in the presence of methionine. We identified three ABC transporters: two stronger transcribed during cysteine limitation and one during methionine depletion. Finally, the expression of genes encoding a methionine γ-lyase, BL929, and a methionine transporter (metPS) was induced in the presence of methionine, in conjunction with a significant increase of volatile sulfur compounds production. Refer to individual Series. This SuperSeries is composed of the following subset Series: GSE25418: BA-Methionine plus Cystine vs Cystine GSE25419: BA-Sulfate vs Cystine GSE25420: BA-Methionine plus Cystine vs Sulfate GSE25421: BA-Sulfate vs Sulfate starvation
Project description:In this study, we profiled the transcriptional changes in a polyphagous spider mite, Tetranychus urticae, after adaptation to spatial and tempospatial stress. We show heritable down-regulation of genes encoding for core enzymes involved in the citric acid and gluconeogenesis/glycolyse pathways (glucose 6-phosphatase among others). Additionally, we observe heritable transcriptional changes in amino acid pathways (methionine, tyrosine and phenylalanine) and in laterally acquired genes from bacteria (cobalamin-independent methionine synthase). By similiar study results in other organisms, we argue that these heritable transcriptional changes (partially) underpin the changed life history traits observed in our experimental evolution set-up.
Project description:Staple crops in human and livestock diets suffer from deficiencies in certain “essential” amino acids including methionine. With the goal of increasing methionine in rice seed, we generated a pair of “PushxPull” double transgenic lines, each containing a methionine-dense seed storage protein (2S albumin from sunflower, HaSSA) and an exogenous enzyme for either methionine (feedback desensitized cystathionine gamma synthase from Arabidopsis, AtD-CGS) or cysteine (serine acetyltransferase from E. coli, EcSAT) biosynthesis. In both double transgenic lines, the total seed methionine content was approximately 50% higher than in their untransformed parental line, Oryza sativa ssp. japonica cv. Taipei 309. HaSSA-containing rice seeds were reported to display an altered seed protein profile, speculatively due to insufficient sulfur amino acid content. However, here we present data suggesting that this may result from an overloaded protein folding machinery in the endoplasmic reticulum rather than primarily from redistribution of limited methionine from endogenous seed proteins to HaSSA. We hypothesize that HaSSA-associated endoplasmic reticulum stress results in redox perturbations that negatively impact sulfate reduction to cysteine, and we speculate that this is mitigated by EcSAT-associated increased sulfur import into the seed, which facilitates additional synthesis of cysteine and glutathione. The data presented here reveal challenges associated with increasing the methionine content in rice seed, including what may be relatively low protein folding capacity in the endoplasmic reticulum and an insufficient pool of sulfate available for additional cysteine and methionine synthesis. We propose that future approaches to further improve the methionine content in rice should focus on increasing seed sulfur loading and avoiding the accumulation of unfolded proteins in the endoplasmic reticulum.
Project description:In this study, we combined metabolic reconstruction, growth assays, metabolome and transcriptome analyses to obtain a global view of the sulfur metabolic network and of the response to sulfur availability in Brevibacterium aurantiacum. In agreement with the growth of B. aurantiacum in the presence of sulfate and cystine, the metabolic reconstruction showed the presence of a sulfate assimilation pathway and of thiolation pathways that produce cysteine (cysE and cysK) or homocysteine (metX and metY) from sulfide, of at least one gene of the transsulfuration pathway (aecD) and of genes encoding three MetE-type methionine synthases. We also compared the expression profiles of B. aurantiacum ATCC9175 during sulfur starvation and in the presence of sulfate, cystine or methionine plus cystine. In sulfur starvation, 690 genes including 21 genes involved in sulfur metabolism and 29 genes encoding amino acids and peptide transporters were differentially expressed. We also investigated changes in pools of sulfur-containing metabolites and in expression profiles after growth in the presence of sulfate, cystine or methionine plus cystine. The expression of genes involved in sulfate assimilation and cysteine synthesis was repressed in presence of cysteine, while the expression of metX, metY, metE1, metE2 and BL613 encoding a probable cystathionine-γ-synthase decreased in the presence of methionine. We identified three ABC transporters: two stronger transcribed during cysteine limitation and one during methionine depletion. Finally, the expression of genes encoding a methionine γ-lyase, BL929, and a methionine transporter (metPS) was induced in the presence of methionine, in conjunction with a significant increase of volatile sulfur compounds production. This SuperSeries is composed of the SubSeries listed below.
Project description:There is an urgent need to develop novel antifungals to tackle the threat that fungal pathogens pose to human health. In this work, we have performed a thorough characterisation and validation of the promising target methionine synthase. We have uncovered that in Aspergillus fumigatus the absence of its enzymatic activity triggers a metabolic imbalance that causes a reduction in intracellular ATP. This drop in cell energetics prevents fungal growth, even in the presence of methionine. Using a tetOFF genetic model to mimic drug treatment we show that repression of methionine synthase in growing hyphae halts growth in vitro, which translates into a beneficial effect in vivo when targeting established infections. Finally, a structural-based virtual screening of methionine synthases reveals key differences between the human and fungal structures and unravels particularities of the fungal pockets that can direct the design of novel specific and broad-spectrum inhibitors. Therefore, methionine synthase is a valuable target for the development of new antifungals.
Project description:Heritable epigenetic factors can contribute to complex disease etiology. In this study we examine, on a global scale, the contribution of DNA methylation to complex traits that are precursors to heart disease, diabetes and osteoporosis. We profiled DNA methylation patterns in the liver using bisulfite sequencing in 90 mouse inbred strains, genome-wide expression levels, proteomics, metabolomics and sixty-eight clinical traits, and performed epigenome-wide association studies (EWAS). We found associations with numerous clinical traits including bone mineral density, plasma cholesterol, insulin resistance, gene expression, protein and metabolite levels. A large proportion of associations were unique to EWAS and were not identified using GWAS. Methylation levels were regulated by genetics largely in cis, but we also found evidence of trans regulation, and we demonstrate that genetic variation in the methionine synthase reductase gene Mtrr affects methylation of hundreds of CpGs throughout the genome. Our results indicate that natural variation in methylation levels contributes to the etiology of complex clinical traits. Reduced representation bisulfite sequencing in mouse strains using liver genomic DNA
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.