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Cell Metabolism Apr 2020Activating transcription factor 4 (ATF4) is a master transcriptional regulator of the integrated stress response (ISR) that enables cell survival under nutrient stress....
Activating transcription factor 4 (ATF4) is a master transcriptional regulator of the integrated stress response (ISR) that enables cell survival under nutrient stress. The mechanisms by which ATF4 couples metabolic stresses to specific transcriptional outputs remain unknown. Using functional genomics, we identified transcription factors that regulate the responses to distinct amino acid deprivation conditions. While ATF4 is universally required under amino acid starvation, our screens yielded a transcription factor, Zinc Finger and BTB domain-containing protein 1 (ZBTB1), as uniquely essential under asparagine deprivation. ZBTB1 knockout cells are unable to synthesize asparagine due to reduced expression of asparagine synthetase (ASNS), the enzyme responsible for asparagine synthesis. Mechanistically, ZBTB1 binds to the ASNS promoter and promotes ASNS transcription. Finally, loss of ZBTB1 sensitizes therapy-resistant T cell leukemia cells to L-asparaginase, a chemotherapeutic that depletes serum asparagine. Our work reveals a critical regulator of the nutrient stress response that may be of therapeutic value.
Topics: Animals; Asparagine; Aspartate-Ammonia Ligase; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation; Humans; Leukemia; Mice, Inbred NOD; Mice, SCID; Repressor Proteins; Transcription, Genetic
PubMed: 32268116
DOI: 10.1016/j.cmet.2020.03.008 -
The Journal of Clinical Investigation Apr 2023The nonessential amino acid asparagine can only be synthesized de novo by the enzymatic activity of asparagine synthetase (ASNS). While ASNS and asparagine have been...
The nonessential amino acid asparagine can only be synthesized de novo by the enzymatic activity of asparagine synthetase (ASNS). While ASNS and asparagine have been implicated in the response to numerous metabolic stressors in cultured cells, the in vivo relevance of this enzyme in stress-related pathways remains unexplored. Here, we found ASNS to be expressed in pericentral hepatocytes, a population of hepatic cells specialized in xenobiotic detoxification. ASNS expression was strongly enhanced in 2 models of acute liver injury: carbon tetrachloride (CCl4) and acetaminophen. We found that mice with hepatocyte-specific Asns deletion were more prone to pericentral liver damage than their control littermates after toxin exposure. This phenotype could be reverted by i.v. administration of asparagine. Unexpectedly, the stress-induced upregulation of ASNS involved an ATF4-independent, noncanonical pathway mediated by the nuclear receptor, liver receptor homolog 1 (LRH-1; NR5A2). Altogether, our data indicate that the induction of the asparagine-producing enzyme ASNS acts as an adaptive mechanism to constrain the necrotic wave that follows toxin administration and provide proof of concept that i.v. delivery of asparagine can dampen hepatotoxin-induced pericentral hepatocellular death.
Topics: Animals; Mice; Asparagine; Hepatocytes; Amino Acids; Liver
PubMed: 36719750
DOI: 10.1172/JCI163508 -
Nature Cancer Nov 2022The pancreatic tumor microenvironment drives deregulated nutrient availability. Accordingly, pancreatic cancer cells require metabolic adaptations to survive and...
The pancreatic tumor microenvironment drives deregulated nutrient availability. Accordingly, pancreatic cancer cells require metabolic adaptations to survive and proliferate. Pancreatic cancer subtypes have been characterized by transcriptional and functional differences, with subtypes reported to exist within the same tumor. However, it remains unclear if this diversity extends to metabolic programming. Here, using metabolomic profiling and functional interrogation of metabolic dependencies, we identify two distinct metabolic subclasses among neoplastic populations within individual human and mouse tumors. Furthermore, these populations are poised for metabolic cross-talk, and in examining this, we find an unexpected role for asparagine supporting proliferation during limited respiration. Constitutive GCN2 activation permits ATF4 signaling in one subtype, driving excess asparagine production. Asparagine release provides resistance during impaired respiration, enabling symbiosis. Functionally, availability of exogenous asparagine during limited respiration indirectly supports maintenance of aspartate pools, a rate-limiting biosynthetic precursor. Conversely, depletion of extracellular asparagine with PEG-asparaginase sensitizes tumors to mitochondrial targeting with phenformin.
Topics: Animals; Mice; Humans; Pancreatic Neoplasms; Asparagine; Adenocarcinoma; Symbiosis; Tumor Microenvironment
PubMed: 36411320
DOI: 10.1038/s43018-022-00463-1 -
Molecular Cell May 2022GLS1 orchestrates glutaminolysis and promotes cell proliferation when glutamine is abundant by regenerating TCA cycle intermediates and supporting redox homeostasis....
GLS1 orchestrates glutaminolysis and promotes cell proliferation when glutamine is abundant by regenerating TCA cycle intermediates and supporting redox homeostasis. CB-839, an inhibitor of GLS1, is currently under clinical investigation for a variety of cancer types. Here, we show that GLS1 facilitates apoptosis when glutamine is deprived. Mechanistically, the absence of exogenous glutamine sufficiently reduces glutamate levels to convert dimeric GLS1 to a self-assembled, extremely low-K filamentous polymer. GLS1 filaments possess an enhanced catalytic activity, which further depletes intracellular glutamine. Functionally, filamentous GLS1-dependent glutamine scarcity leads to inadequate synthesis of asparagine and mitogenome-encoded proteins, resulting in ROS-induced apoptosis that can be rescued by asparagine supplementation. Physiologically, we observed GLS1 filaments in solid tumors and validated the tumor-suppressive role of constitutively active, filamentous GLS1 mutants K320A and S482C in xenograft models. Our results change our understanding of GLS1 in cancer metabolism and suggest the therapeutic potential of promoting GLS1 filament formation.
Topics: Apoptosis; Asparagine; Glutaminase; Glutamine; Humans; Reactive Oxygen Species
PubMed: 35381197
DOI: 10.1016/j.molcel.2022.03.016 -
Nature Metabolism Aug 2023Robust and effective T cell immune surveillance and cancer immunotherapy require proper allocation of metabolic resources to sustain energetically costly processes,...
Robust and effective T cell immune surveillance and cancer immunotherapy require proper allocation of metabolic resources to sustain energetically costly processes, including growth and cytokine production. Here, we show that asparagine (Asn) restriction on CD8 T cells exerted opposing effects during activation (early phase) and differentiation (late phase) following T cell activation. Asn restriction suppressed activation and cell cycle entry in the early phase while rapidly engaging the nuclear factor erythroid 2-related factor 2 (NRF2)-dependent stress response, conferring robust proliferation and effector function on CD8 T cells during differentiation. Mechanistically, NRF2 activation in CD8 T cells conferred by Asn restriction rewired the metabolic program by reducing the overall glucose and glutamine consumption but increasing intracellular nucleotides to promote proliferation. Accordingly, Asn restriction or NRF2 activation potentiated the T cell-mediated antitumoral response in preclinical animal models, suggesting that Asn restriction is a promising and clinically relevant strategy to enhance cancer immunotherapy. Our study revealed Asn as a critical metabolic node in directing the stress signaling to shape T cell metabolic fitness and effector functions.
Topics: Animals; CD8-Positive T-Lymphocytes; NF-E2-Related Factor 2; Asparagine; Glucose; Neoplasms
PubMed: 37550596
DOI: 10.1038/s42255-023-00856-1 -
Cell Communication and Signaling : CCS Mar 2024Asparagine, an important amino acid in mammals, is produced in several organs and is widely used for the production of other nutrients such as glucose, proteins, lipids,... (Review)
Review
Asparagine, an important amino acid in mammals, is produced in several organs and is widely used for the production of other nutrients such as glucose, proteins, lipids, and nucleotides. Asparagine has also been reported to play a vital role in the development of cancer cells. Although several types of cancer cells can synthesise asparagine alone, their synthesis levels are insufficient to meet their requirements. These cells must rely on the supply of exogenous asparagine, which is why asparagine is considered a semi-essential amino acid. Therefore, nutritional inhibition by targeting asparagine is often considered as an anti-cancer strategy and has shown success in the treatment of leukaemia. However, asparagine limitation alone does not achieve an ideal therapeutic effect because of stress responses that upregulate asparagine synthase (ASNS) to meet the requirements for asparagine in cancer cells. Various cancer cells initiate different reprogramming processes in response to the deficiency of asparagine. Therefore, it is necessary to comprehensively understand the asparagine metabolism in cancers. This review primarily discusses the physiological role of asparagine and the current progress in the field of cancer research.
Topics: Animals; Asparagine; Neoplasms; Leukemia; Amino Acids; Glucose; Mammals
PubMed: 38448969
DOI: 10.1186/s12964-024-01540-x -
Frontiers in Bioscience (Scholar... Jan 2011Acrylamide has been classified as a probable carcinogen and can be ingested, inhaled (e.g. tobacco smoke), or absorbed. Fried, starchy foods are the most prominent... (Review)
Review
Acrylamide has been classified as a probable carcinogen and can be ingested, inhaled (e.g. tobacco smoke), or absorbed. Fried, starchy foods are the most prominent sources of exposure. The reaction between asparagine and fructose typically produces the most acrylamide in foods from plant sources. Preparation methods shown to affect acrylamide production include temperature and cooking oil. Hemoglobin adducts present a reliable short term measurement of acrylamide exposure; a variety of methods, predominately LC/MS-MS, have been used for acrylamide detection. Health effects of acrylamide include neurotoxicity and genotoxicity. It is believed that the electrophilic nature of acrylamide will allow it to adduct to thiol groups on nerve axons and proteins that regulate neurotransmitter exocytosis. Presynaptic nitric oxide (NO) may also play a role here. Reproductively, males demonstrate a decrease in sperm count, motility and morphology. Acrylamide produces clastogenic effects while glycidamide (GA), its metabolite, produces mutagenic effects. A number of protective measures against the effects of acrylamide are possible including probiotics, increased use of compounds known to decrease acrylamide production and bioengineering of precursor foods such as potatoes.
Topics: Acrylamide; Animals; Asparagine; Axons; Environmental Exposure; Epoxy Compounds; Exocytosis; Food Analysis; Humans; Male; Mutagens; Neurotoxins; Nitric Oxide; Spermatozoa; Tobacco Smoke Pollution
PubMed: 21196355
DOI: 10.2741/s130 -
Food Chemistry Apr 2017Acrylamide is produced from free asparagine and reducing sugars during high-temperature cooking and food processing, and potato products are major contributors to...
Acrylamide-forming potential of potatoes grown at different locations, and the ratio of free asparagine to reducing sugars at which free asparagine becomes a limiting factor for acrylamide formation.
Acrylamide is produced from free asparagine and reducing sugars during high-temperature cooking and food processing, and potato products are major contributors to dietary acrylamide intake. The present study analysed twenty varieties of potatoes grown at two sites (Doncaster and Woburn) in the United Kingdom to assess the effect of location of cultivation on acrylamide-forming potential. Analysis of variance revealed a full site by variety nested within type (French fry, boiling and crisping) by storage interaction for acrylamide (p<0.003, F-test), reducing sugars and total sugars (p<0.001, F-test). There was much greater free asparagine in potatoes grown at the Doncaster site compared with the Woburn site. Modelling of the relationship between the ratio of free asparagine to reducing sugars and the levels of acrylamide identified a value of 2.257±0.149 as the tipping point in the ratio below which free asparagine concentration could affect acrylamide formation.
Topics: Acrylamide; Amino Acids; Asparagine; Carbohydrates; Food Handling; Hot Temperature; Solanum tuberosum; United Kingdom
PubMed: 27855938
DOI: 10.1016/j.foodchem.2016.09.199 -
Cell Metabolism May 2018Cancer cells frequently hijack normal metabolic pathways to promote their growth and metastasis. Two recent papers by Knott et al. (2018) and Pavlova et al. (2018)...
Cancer cells frequently hijack normal metabolic pathways to promote their growth and metastasis. Two recent papers by Knott et al. (2018) and Pavlova et al. (2018) demonstrate that asparagine and glutamine work in concert to drive tumor growth and metastasis through modulation of cell survival, growth, and EMT regulatory pathways.
Topics: Asparagine; Biological Availability; Breast Neoplasms; Glutamine; Humans; Metabolic Networks and Pathways
PubMed: 29719230
DOI: 10.1016/j.cmet.2018.04.012 -
Biotechnology and Bioengineering Mar 2022Chinese hamster ovary (CHO) cell lines are grown in cultures with varying asparagine and glutamine concentrations, but further study is needed to characterize the...
Chinese hamster ovary (CHO) cell lines are grown in cultures with varying asparagine and glutamine concentrations, but further study is needed to characterize the interplay between these amino acids. By following C-glucose, C-glutamine, and C-asparagine tracers using metabolic flux analysis (MFA), CHO cell metabolism was characterized in an industrially relevant fed-batch process under glutamine supplemented and low glutamine conditions during early and late exponential growth. For both conditions MFA revealed glucose as the primary carbon source to the tricarboxylic acid (TCA) cycle followed by glutamine and asparagine as secondary sources. Early exponential phase CHO cells prefer glutamine over asparagine to support the TCA cycle under the glutamine supplemented condition, while asparagine was critical for TCA activity for the low glutamine condition. Overall TCA fluxes were similar for both conditions due to the trade-offs associated with reliance on glutamine and/or asparagine. However, glutamine supplementation increased fluxes to alanine, lactate and enrichment of glutathione, N-acetyl-glucosamine and pyrimidine-containing-molecules. The late exponential phase exhibited reduced central carbon metabolism dominated by glucose, while lactate reincorporation and aspartate uptake were preferred over glutamine and asparagine. These C studies demonstrate that metabolic flux is process time dependent and can be modulated by varying feed composition.
Topics: Animals; Asparagine; CHO Cells; Cricetinae; Cricetulus; Glucose; Glutamine; Lactic Acid
PubMed: 34786689
DOI: 10.1002/bit.27993