The Malate Shuttle Detoxifies Ammonia in Exhausted T Cells by Producing 2-Ketoglutarate
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ABSTRACT:
PROVIDER: PRJNA911793 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR22715500_1.fastq.gz | Fastqsanger.gz | |||
| SRR22715500_2.fastq.gz | Fastqsanger.gz | |||
| SRR22715501_1.fastq.gz | Fastqsanger.gz | |||
| SRR22715501_2.fastq.gz | Fastqsanger.gz | |||
| SRR22715502_1.fastq.gz | Fastqsanger.gz |
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Project description:The malate shuttle is traditionally known to maintain the NAD+/NADH balance between the cytosol and mitochondria. Whether the malate shuttle has additional functions was unknown. Here we show that chronic viral infections induced the expression of GOT1, the key enzyme in the malate shuttle, in CD8+ T cells. Got1 deficiency indeed decreased the NAD+/NADH ratio and dampened antiviral CD8+ T cell responses to chronic infection; however, increasing the NAD+/NADH ratio did not restore antiviral T cell responses. Got1 deficiency reduced the production of the ammonia scavenger 2-ketoglutarate and led to toxic ammonia accumulation in CD8+ T cells. Supplementation with 2-ketoglutarate assimilated and detoxified ammonia in Got1-deficient T cells and restored antiviral responses. This study suggests that the major function of the malate shuttle in CD8+ T cells is not to maintain the NAD+/NADH ratio, but rather to detoxify ammonia and enable sustainable ammonia-neutral glutamine catabolism in CD8+ T cells during chronic infections.
2023-09-01 | GSE220876 | GEO
Project description:The malate shuttle is traditionally understood to maintain NAD+/NADH balance between the cytosol and mitochondria. Whether the malate shuttle has additional functions is unclear. Here we show that chronic viral infections induce CD8+ T cell expression of GOT1, a central enzyme in the malate shuttle. Got1 deficiency decreased the NAD+/NADH ratio and limited antiviral CD8+ T cell responses to chronic infection; however, increasing the NAD+/NADH ratio did not restore T cell responses. Got1 deficiency reduced the production of the ammonia scavenger 2-ketoglutarate (2-KG) from glutaminolysis and led to a toxic accumulation of ammonia in CD8+ T cells. Supplementation with 2-KG assimilated and detoxified ammonia in Got1-deficient T cells and restored antiviral responses. These data indicate that the major function of the malate shuttle in CD8+ T cells is not to maintain the NAD+/NADH balance but rather to detoxify ammonia and enable sustainable ammonia-neutral glutamine catabolism in CD8+ T cells during chronic infection.
| S-EPMC10602850 | biostudies-literature
Project description:Glioblastoma (GBM) ranks among the most lethal of human cancers with current therapies offering only palliation. GBM displays striking intratumoral heterogeneity with diversity of cell state, metabolism, and molecular regulation. Here, we demonstrate that stem-like tumor cells, designated GBM stem cells (GSCs), display higher activity of the malate aspartate shuttle (MAS) through increased expression of malate dehydrogenase 2 (MDH2). Genetic and pharmacologic targeting of MDH2 reduced GSC proliferation, self-renewal, and in vivo tumor growth. MDH2 targeting induced accumulation of alpha-ketoglutarate (αKG), a critical enzymatic co-factor. Mechanistically, MDH2 regulated post-transcriptional regulation of mRNA, specifically N6-Methyladenosine (m6A) with platelet-derived growth factor receptor- (PDGFR) as a regulated transcript. Leveraging these observations, targeting MDH2 and PDGFR displayed combinatorial efficacy against GSCs. Collectively, these results suggest that stem-like tumor cells reprogram their metabolism to induce changes in their epitranscriptomes that reveal possible therapeutic paradigms.
2024-10-15 | GSE255535 | GEO
Project description:Purpose: Understanding the mechanism of malate accumulation in plants is beneficial for both plant nutrient and human health. However, little is known regarding regulation of malate accumulation in horticulture plants such as tomato. The goals of this study are to investigate potential regulation network of Al-Activated Malate Transporter 9 (ALMT9) which is the major locus responsible for the variation in fruit malate concentration observed in cultivared tomato. Methods: The transcriptomes of fruit at ripening stage from CK and SlALMT9 overexpressing line1 were evaluated using single-ended sequencing of Illumina HiSeq 2500. Raw sequences were filtered and the resulting sets of clean reads were used for the following analysis by tophat and edgeR software. Results: Among 1,887 differentially expressed genes, some structural genes involved in sugar and organic acid metabolism were differently expressed in SlALMT9 overexpressing line, which partially coincide with changes of sugar and organic acid concentration. PR genes was also altered in the OX lines, in agreement with previous study that tomato fruit malate is involved in pathogen infection. Three members of malate transporters, MATE (multidrug and toxin efflux), were up-regulated (SlMATE5 and 6) or down-regulated (SlMATE9) . Besides, three sugar transport proteins and four vacuole membrane or plasma membrane proteins were up-regulated in OX line Conclusions: Using RNA-seq analysis, 1,887 differentially expressed genes was revealed. Among them, several genes related to sugar and organic acid metabolism and transport, pathogen resistances were identified. This transcriptome study provides insight into the regulatory mechanism of fruit malate accumulation and the effect of the SlALMT9 to primary metabolism.
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Project description:Fresh human breast tumor tissue was dissociated into single cells and viably frozen. Patient samples were annotated as having an ""exhausted"" or ""non-exhausted"" immune environment based on CyTOF characterization of T cell phenotypes (Wagner et al, Cell 2019). 14 samples (7 exhausted, 7 non-exhausted) were selected for scRNA-seq (without prior cell type enrichment) with the goal to compare the two immune environment types and to comprehensively characterize exhaustion-associated features of the tumor microenvironment.
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Project description:To better understand the malate-mediated metabolism and related regulatory profiles of L. hongkongensis, we compared the respective expression profiles of L. hongkongensis cells grown in modified M63 media supplemented with or without malate using high-throughput RNA-sequencing.
2019-09-30 | GSE135058 | GEO
Project description:Over the last few years, various inborn disorders have been reported in the malate aspartate shuttle (MAS). The MAS consists of four metabolic enzymes and two transporters, one of them having two isoforms that are expressed in different tissues. Together they form a biochemical pathway that shuttles electrons from the cytosol into mitochondria, as the inner mitochondrial membrane is impermeable to the electron carrier NADH. By shuttling NADH across the mitochondrial membrane in the form of a reduced metabolite (malate), the MAS plays an important role in mitochondrial respiration. In addition, the MAS maintains the cytosolic NAD+ /NADH redox balance, by using redox reactions for the transfer of electrons. This explains why the MAS is also important in sustaining cytosolic redox-dependent metabolic pathways, such as glycolysis and serine biosynthesis. The current review provides insights into the clinical and biochemical characteristics of MAS deficiencies. To date, five out of seven potential MAS deficiencies have been reported. Most of them present with a clinical phenotype of infantile epileptic encephalopathy. Although not specific, biochemical characteristics include high lactate, high glycerol 3-phosphate, a disturbed redox balance, TCA abnormalities, high ammonia, and low serine, which may be helpful in reaching a diagnosis in patients with an infantile epileptic encephalopathy. Current implications for treatment include a ketogenic diet, as well as serine and vitamin B6 supplementation.
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Project description:In order to propagate a solid tumor, cancer cells must adapt to and survive under various tumor microenvironment (TME) stresses, such as hypoxia or lactic acidosis. To systematically identify genes that modulate cancer cell survival under stresses, we performed genome-wide shRNA screens under hypoxia or lactic acidosis. We discovered that genetic depletion of acetyl-CoA carboxylase (ACACA or ACC1) or ATP citrate lyase (ACLY) protected cancer cells from hypoxia-induced apoptosis. Additionally, loss of ACLY or ACC1 reduced levels and activities of the oncogenic transcription factor ETV4. Silencing ETV4 also protected cells from hypoxia-induced apoptosis and led to remarkably similar transcriptional responses as with silenced ACLY or ACC1, including an anti-apoptotic program. Metabolomic analysis found that while α-ketoglutarate levels decrease under hypoxia in control cells, α-ketoglutarate is paradoxically increased by hypoxia when ACC1 or ACLY are depleted. Supplementation with α-ketoglutarate rescued the hypoxia-induced apoptosis and recapitulated the decreased expression and activity of ETV4 via an epigenetic mechanism. Therefore, ACC1 and ACLY regulate the levels of ETV4 under hypoxia via increased α-ketoglutarate. These results reveal that ACC1/ACLY- α-ketoglutarate-ETV4 is a novel means by which metabolic states regulate transcriptional output for life vs. death decisions under hypoxia. Since many lipogenic inhibitors are under investigation as cancer therapeutics, our findings suggest that the use of these inhibitors will need to be carefully considered with respect to oncogenic drivers, tumor hypoxia, progression and dormancy. More broadly, our screen provides a framework for studying additional tumor cell stress-adaption mechanisms in the future. DESIGN: H1975 lung cancer cells transduced with a scramble shRNA hairpin or two different shRNAs against ACLY, ACC1, or ETV4 under hypoxia.
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Project description:Mitochondrial Malate Dehydrogenase 2 has been identified as an RNA-binding protein in several RNA-interactome capture studies. Here, we used eCLIP to identify the RNA targets bound by human MDH2. We identify cytosolic RNA targets for MDH2, as well as several mitochondrial tRNAs.
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Project description:Tet3 is an Fe2+-dependent enzyme that oxidizes genomic 5-methylcytosine to 5-hydroxymethylcytosine with the help of alpha-ketoglutarate and oxygen. It is the most abundant Tet enzyme in differentiated tissues including brain. Adult brain contains the highest 5-hydroxymethylcytosine levels. How alpha-ketoglutarate is made available for the oxidation of mC in brain cells and how the Tet activity is linked to neural activity are unsolved questions. Our experiments with full mouse brains show that Tet3 interacts in the nucleus directly with selected enzymes of the mitochondrial citric acid cycle. This leads to the formation of isocitrate. Tet3 also interacts with aspartate aminotransferase, which produces oxaloacetate. Although oxaloacetate and isocitrate are biosynthetic alpha-ketoglutarate precursors, they function as inhibitors of Tet3 and are needed to protect the reactive Fe2+ center from degrading DNA. The supply of Tet3 with alpha-ketoglutarate is established by a direct interaction of Tet3 with glutamate dehydrogenase (Glud1), which converts the neurotransmitter glutamate directly into alpha-ketoglutarate. This links Tet3 function to neural activity.
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