Transcriptome change caused by lowered intracellular S-adenosylmethionine level in the X63/0 mouse plasma cell line.
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE106674 | GEO | 2017/11/09
SECONDARY ACCESSION(S): PRJNA417590
REPOSITORIES: GEO
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Project description:One-carbon metabolism is a universal hub for cellular metabolism and epigenetic regulation.1–3 Here, we report that formaldehyde (FA), a one-carbon unit that organisms produce in substantial quantities through folate metabolism,4 is a regulator of the one-carbon cycle via the biosynthesis of S-adenosyl-L-methionine (SAM), an essential one-carbon building block for synthesis of nucleotides, amino acids, and methylated nucleic acids and proteins.5 Activity-based protein profiling (ABPP) in mouse liver tissue identifies FA-sensitive cysteine sites across the proteome, revealing several one-carbon cycle targets including S-adenosylmethionine synthetase isoform 1 (MAT1A), the terminal enzyme in SAM biosynthesis. Biochemical studies of the formaldehyde-MAT1A interaction establish FA-dependent inhibition of MAT1A activity through a conserved C120 site, as the MAT2A isoform lacking this cysteine is not FA-sensitive. CRISPR knockout-generated HepG2 cell models that predominantly express either MAT1A or MAT2A show that MAT1A-positive cells respond to FA treatment in a dose-dependent manner by decreasing their SAM levels and downstream RNA methylation, whereas the MAT2A-positive cells are not affected by FA. Our findings reveal an unexpected interplay between SAM and FA, two central one-carbon units to influence the overall methylation potential of the cell.
2023-11-02 | PXD018251 | Pride
Project description:Methionine adenosyltransferase (MAT) catalyzes the synthesis of S-adenosylmethionine (SAM). As the sole methyl-donor of methylation of DNA, RNA and proteins, SAM amount affects gene expression by changing their methylation. Expression of MAT2A, the catalytic subunit of isozyme MAT2, is positively correlated with proliferation of cancer cells. However, how MAT2A promotes cell proliferation is largely unknown. Given that the protein synthesis is induced in proliferating cells and that RNA and protein components of translation machinery are methylated, we tested whether MAT2 and SAM are coupled with protein synthesis. By measuring ongoing protein translation with puromycin labeling in HeLa and Hepa1 cells, we revealed that MAT2A depletion by siRNA or chemical inhibition by cycloleucine reduced protein synthesis in mammalian cells. Overexpression of MAT2A enhanced protein synthesis, indicating that SAM is limiting under normal culture conditions. MAT2 inhibition did not accompany a reduction in the mTORC1 activity but reduced polysome formation. Polysome-bound RNA sequencing revealed that MAT2 inhibition decreased translation efficiency of a fraction of mRNAs. MAT2A was also found to interact with the proteins involved in rRNA processing and ribosome biogenesis. Depletion or inhibition of MAT2 reduced 18S rRNA processing. In addition, by quantitative mass spectrometry, we observed that some translation factors were dynamically methylated in response to the activity of MAT2A or the availability of SAM. These observations suggest that cells possess an mTOR-independent regulatory mechanism that tunes translation in response to the amount of SAM. Such a system may acclimate cells for survival when SAM synthesis is reduced whereas it may support proliferation when SAM is sufficient.
2022-12-21 | GSE201299 | GEO
Project description:Maintenance of the intracellular levels of the methyl donor S-adenosylmethionine (SAM) is essential for a wide variety of biological processes. We demonstrate that the N6-adenosine methyltransferase METTL16 regulates expression of MAT2A, which encodes the only SAM synthetase expressed in most cells. Upon SAM depletion by methionine starvation, cells induce MAT2A expression by enhanced splicing of a retained intron. Induction requires METTL16 and its methylation substrate, a vertebrate conserved hairpin (hp1) in the MAT2A 3´ UTR. Increasing METTL16 occupancy on the MAT2A 3´ UTR is sufficient to induce efficient splicing. We propose that under SAM-limiting conditions, METTL16 occupancy on hp1 increases due to inefficient enzymatic turnover, which in turn promotes MAT2A splicing. Interestingly, human and S. pombe METTL16 methylate the U6 spliceosomal snRNA at a sequence identical to hp1. These observations suggest that the conserved U6 snRNA methyltransferase evolved an additional function in vertebrates to regulate SAM homeostasis.
2017-05-18 | GSE90914 | GEO
Project description:Transcriptome change caused by lowered intracellular S-adenosylmethionine level in the X63/0 mouse plasma cell line.
| PRJNA417590 | ENA
Project description:NUDT21 encodes the CFIm25 protein, a component of the CFIm complex that regulates alternative polyadenylation (APA). Our data suggest that the CFIm complex also induces splicing of a detained intron in the the S-adenosylmethionine (SAM) synthetase MAT2A to control intracellular levels of SAM. To genetically separate these functions, we used poly(A) Click-seq (PAC-seq) to determine the changes in poly(A) site selection in two cell lines. The parental cell line is the colorectal cell line HCT116 and a derivative line that has the detained intron of MAT2A deleted in both alleles of MAT2A (116-DDI). We found few differences in alternative polyadenylation after CFIm25 depletion were similar supporting teh conclusion that CFIm's role in APA is mechanistically distinct from its role in regulation of MATA splicing.
2021-05-04 | GSE158591 | GEO
Project description:Hepatic stellate cell (HSC) activation induced by transforming growth factor β (TGF-β1) plays a pivotal role in the fibrogenesis. The complex downstream mediators of TGF-β1 are largely unknown. Here, proteomics analysis and biological validation demonstrated that methionine adenosyltransferase 2A (MAT2A) was significantly upregulated in a CCl4-induced fibrosis mice model and a small molecule NPLC0393, known to block TGF-β1/Smad3 signaling, inhibited its upregulation. In HSC cells, TGF-β1 induced elevation of MAT2A and MAT2β expression as well as reduction of S-adenosylmethionine (SAM) content, which further promoted HSC activation. Functionally, in vivo and in vitro knockdown of MAT2A alleviated CCl4- and TGF-β1-induced HSC activation, whereas in vivo overexpression of MAT2A facilitated hepatic fibrosis and abolished therapeutic effect of NPLC0393. TGF-β1 induced p65 phosphorylation and NF-κB activation, thereby promoted the transcription of MAT2A and its protein expression. In addition, overexpression of p65 abrogated NPLC0393 mediated inhibition of HSC activation. This study identified a novel pathway TGF-β1/p65/MAT2A that was involved in the regulation of intracellular SAM contents and liver fibrogenesis, suggesting that this pathway is a potential therapeutic target for hepatic fibrosis.
2019-11-12 | PXD011134 | Pride
Project description:Hepatic stellate cell (HSC) activation induced by transforming growth factor β (TGF-β1) plays a pivotal role in the fibrogenesis. The complex downstream mediators of TGF-β1 are largely unknown. Here, proteomics analysis and biological validation demonstrated that methionine adenosyltransferase 2A (MAT2A) was significantly upregulated in a CCl4-induced fibrosis mice model and a small molecule NPLC0393, known to block TGF-β1/Smad3 signaling, inhibited its upregulation. In HSC cells, TGF-β1 induced elevation of MAT2A and MAT2β expression as well as reduction of S-adenosylmethionine (SAM) content, which further promoted HSC activation. Functionally, in vivo and in vitro knockdown of MAT2A alleviated CCl4- and TGF-β1-induced HSC activation, whereas in vivo overexpression of MAT2A facilitated hepatic fibrosis and abolished therapeutic effect of NPLC0393. TGF-β1 induced p65 phosphorylation and NF-κB activation, thereby promoted the transcription of MAT2A and its protein expression. In addition, overexpression of p65 abrogated NPLC0393 mediated inhibition of HSC activation. This study identified a novel pathway TGF-β1/p65/MAT2A that was involved in the regulation of intracellular SAM contents and liver fibrogenesis, suggesting that this pathway is a potential therapeutic target for hepatic fibrosis.
2019-11-12 | PXD011135 | Pride
Project description:One-carbon metabolism is an essential branch of cellular metabolism that intersects with epigenetic regulation. Here, we show formaldehyde, a one-carbon unit derived from both endogenous sources and environmental exposure, regulates one-carbon metabolism by inhibiting the biosynthesis of S-adenosylmethionine (SAM), the major methyl donor in cells. Formaldehyde reacts with privileged, hyperreactive cysteine sites in the proteome, including Cys120 in S-adenosylmethionine synthase isoform type-1 (MAT1A). Formaldehyde exposure inhibited MAT1A activity and decreased SAM production with MAT-isoform specificity. A genetic mouse model of chronic formaldehyde overload showed a decrease in SAM and in methylation on selected histones and genes. Epigenetic and transcriptional regulation of Mat1a and related genes function as compensatory mechanisms for formaldehyde-dependent SAM depletion, revealing a biochemical feedback cycle between formaldehyde and SAM one-carbon units.
2023-09-05 | GSE242266 | GEO
Project description:This study examines the therapeutic plausibility of using universal methyl group donor S-adenosylmethionine (SAM) to block breast cancer development, growth, and metastasis. cancer. Anti-tumor and anti-metastatic activity of SAM was evaluated through a series of studies in vitro using two different human breast cancer cell lines and in vivo using a MDA-MB-231 xenograft model of breast cancer. The data shown in this array is obtained from control and SAM-treated MDA-MB-231 cell lines.
2017-04-28 | GSE98275 | GEO
Project description:Gliomas bearing driver mutations of histone 3 lysine 27 (H3K27M) are incurable brain tumors. H3K27M mutant tumors display unique epigenomes with global loss of the chromatin repressive H3K27 trimethylation mark. Here, we generated a syngeneic H3K27M mouse model to study the dependence upon amino acid (AA) metabolism by performing an AA drop out screen. H3K27M mutant cells, but not histone wildtype cells, were highly dependent on the amino acid, methionine. Interrogating the methionine cycle dependency through an siRNA screen identified the enzyme Methionine Adenosyltransferase 2A (MAT2A), which catalyzes production of S-adenosylmethionine (SAM), a methyl donor. Sensitivity to MAT2A loss in H3K27M mutant cells was not mediated through the canonical mechanism of MTAP deletion; instead, H3K27M mutant cells have lower MAT2A protein levels, which is mediated by Adenosylmethionine Decarboxylase 1 (AMD1) production of decarboxylated SAM (dcSAM). MAT2A loss induces global depletion of H3K36me3, a potent chromatin mark of transcriptional elongation, as evaluated by quantitative chromatin immunoprecipitation with reference exogenous genome sequencing (ChIP-Rx-Seq) in multiple DIPG lines. Tandem H3K36me3 ChIP-Rx-seq and RNA-seq identified several oncogenic and developmental transcriptional programs associated with MAT2A loss. Moreover, inducible knockdown of MAT2A or methionine-restricted diets (MR) extended survival in both syngeneic and patient-derived xenograft models (PDXs) in vivo. Collectively, our results provide novel connections between AA metabolism and the epigenome in H3K27M gliomas, suggesting that MAT2A, a central regulator of methionine metabolism, presents exploitable therapeutic vulnerabilities in H3K27M gliomas.
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