An alternative route for β-hydroxybutyrate metabolism supports cytosolic acetyl-CoA synthesis in cancer cells.

Cancer cells are exposed to diverse metabolites in the tumour microenvironment that are used to support the synthesis of nucleotides, amino acids and lipids needed for rapid cell proliferation. In some tumours, ketone bodies such as β-hydroxybutyrate (β-OHB), which are elevated in circulation under fasting conditions or low glycemic diets, can serve as an alternative fuel that is metabolized in the mitochondria to provide acetyl-CoA for the tricarboxylic acid (TCA) cycle. Here we identify a non-canonical route for β-OHB metabolism that bypasses the TCA cycle to generate cytosolic acetyl-CoA.

Nrf2 drives activation-driven expansion of CD4T cells by modulating glucose and glutamine metabolism.

Upon antigenic stimulation, CD4T cells undergo clonal expansion elevating their bioenergetic demands and utilization of nutrients like glucose and glutamine. The nuclear factor erythroid-2-related factor 2 (Nrf2) is a well-known regulator of oxidative stress, but its involvement in modulating the metabolism of CD4T cells remains unexplored. We report that Nrf2 protein levels are temporally regulated in activated CD4T cells, with elevated expression during early activation followed by a decline.

Resolving early embryonic metabolism in Drosophila through single-embryo metabolomics and transcriptomics.

Early embryonic development marks a shift from maternal factor reliance to zygotic control. Although transcriptional regulation during this period is well characterized, concurrent metabolic events remain largely unknown. Progress has been limited by technical challenges in analysing the small amounts of material and the rapid progression of development.

Glucose-dependent glycosphingolipid biosynthesis fuels CD8 T cell function and tumor control.

Glucose is essential for T cell proliferation and function, yet its specific metabolic roles in vivo remain poorly defined. Here, we identify glycosphingolipid (GSL) biosynthesis as a key pathway fueled by glucose that enables CD8 T cell expansion and cytotoxic function in vivo. Using C-based stable isotope tracing, we demonstrate that CD8 effector T cells use glucose to synthesize uridine diphosphate-glucose (UDP-Glc), a precursor for glycogen, glycan, and GSL biosynthesis.

The prostacyclin receptor PTGIR is a NRF2-dependent regulator of CD8 T cell exhaustion.

CD8 T cell exhaustion (T) limits immune control of cancer, but the underlying molecular drivers are unclear. In the present study, we identified the prostaglandin I (prostacyclin) receptor PTGIR as a cell-intrinsic regulator of T cell exhaustion. Transcriptomic profiling of terminally exhausted (T) CD8 T cells revealed increased activation of the nuclear factor erythroid 2-related factor 2 (NRF2) oxidative stress response pathway.

High Baseline Plasma Anthranilic Acid Predicts Remission Upon Acute-Series Ketamine Infusion for Treatment-Resistant Depression.

Background: Treatment-resistant depression (TRD) remains a challenge, but intravenous racemic ketamine offers rapid antidepressant effects. Reliable biomarkers are needed. In this study, we examined kynurenine pathway metabolites and inflammatory cytokines as predictors of ketamine response.

Polyamine quantitation by LC-MS using isobutyl chloroformate derivatives.

Polyamines are an important class of metabolites that are poorly covered in standard metabolomics workflows. Here, we describe a protocol for isobutyl-chloroformate derivatization that can be applied to metabolite extracts following other metabolomics applications. This simple procedure allows for quantitative measurement of thirteen polyamines and two internal standards in a short (15-minute) LC-MS method.

Sex differences in peripheral and central dysregulation of the kynurenine pathway in Parkinson's disease.

We previously demonstrated that kynurenine pathway (KP) dysregulation associates with Parkinson's disease (PD) and its symptoms. Here, we profiled 16 KP-related markers in a second, independent cohort; plasma: n = 202 (116 PD ("OFF"), 86 controls); CSF: n = 183 (108, 75). Consistent with previous findings, we detected significantly higher concentrations of neurotoxic 3-hydroxykynurenine in plasma and lower concentrations of neuroprotective kynurenic acid along with higher neurotoxic quinolinic acid/kynurenic acid ratios in CSF of PD patients.

Sperm meet the elevated energy demands to attain fertilization competence by increasing flux through aldolase.

Unlabelled: Prior to ejaculation, sperm are stored in the epididymis in a 'resting' metabolic state. Upon ejaculation, sperm must alter their metabolism to generate the energy needed to support the motility and maturation process known as capacitation to reach and fertilize the oocyte. How sperm regulate the capacitation-induced increase in carbon flux is unknown.

Mitochondrial fatty acid synthesis and MECR regulate CD4+ T cell function and oxidative metabolism.

Imbalanced effector and regulatory CD4+ T cell subsets drive many inflammatory diseases. These T cell subsets rely on distinct metabolic programs, modulation of which differentially affects T cell fate and function. Lipid metabolism is fundamental yet remains poorly understood across CD4+ T cell subsets.

Nutrient-driven histone code determines exhausted CD8 T cell fates.

Exhausted T cells (TEX) in cancer and chronic viral infections undergo metabolic and epigenetic remodeling, impairing their protective capabilities. However, the impact of nutrient metabolism on epigenetic modifications that control TEX differentiation remains unclear. We showed that TEX cells shifted from acetate to citrate metabolism by down-regulating acetyl-CoA synthetase 2 (ACSS2) while maintaining ATP-citrate lyase (ACLY) activity.

Dietary Restriction Enhances CD8 T Cell Ketolysis to Limit Exhaustion and Boost Anti-Tumor Immunity.

Reducing calorie intake without malnutrition limits tumor progression but the underlying mechanisms are poorly understood. Here we show that dietary restriction (DR) suppresses tumor growth by enhancing CD8 T cell-mediated anti-tumor immunity. DR reshapes CD8 T cell differentiation within the tumor microenvironment (TME), promoting the development of effector T cell subsets while limiting the accumulation of exhausted T (Tex) cells, and synergizes with anti-PD1 immunotherapy to restrict tumor growth.

Metabolomics and C labelled glucose tracing to identify carbon incorporation into aberrant cell membrane glycans in cancer.

Cell membrane glycans contribute to immune recognition, signaling, and cellular adhesion and migration, and altered membrane glycosylation is a feature of cancer cells that contributes to cancer progression. The uptake and metabolism of glucose and other nutrients essential for glycan synthesis could underlie altered membrane glycosylation, but the relationship between shifts in nutrient metabolism and the effects on glycans have not been directly examined. We developed a method that combines stable isotope tracing with metabolomics to enable direct observations of glucose allocation to nucleotide sugars and cell-membrane glycans.

An alternative route for β-hydroxybutyrate metabolism supports fatty acid synthesis in cancer cells.

Cancer cells are exposed to diverse metabolites in the tumor microenvironment that are used to support the synthesis of nucleotides, amino acids, and lipids needed for rapid cell proliferation. Recent work has shown that ketone bodies such as β-hydroxybutyrate (β-OHB), which are elevated in circulation under fasting conditions or low glycemic diets, can serve as an alternative fuel that is metabolized in the mitochondria to provide acetyl-CoA for the tricarboxylic acid (TCA) cycle in some tumors. Here, we discover a non-canonical route for β-OHB metabolism, in which β-OHB can bypass the TCA cycle to generate cytosolic acetyl-CoA for fatty acid synthesis in cancer cells.

A hierarchical hepatic de novo lipogenesis substrate supply network utilizing pyruvate, acetate, and ketones.

Hepatic de novo lipogenesis (DNL) is a fundamental physiologic process that is often pathogenically elevated in metabolic disease. Treatment is limited by incomplete understanding of the metabolic pathways supplying cytosolic acetyl-CoA, the obligate precursor to DNL, including their interactions and proportional contributions. Here, we combined extensive C tracing with liver-specific knockout of key mitochondrial and cytosolic proteins mediating cytosolic acetyl-CoA production.

Glucose-dependent glycosphingolipid biosynthesis fuels CD8 T cell function and tumor control.

Glucose is essential for T cell proliferation and function, yet its specific metabolic roles remain poorly defined. Here, we identify glycosphingolipid (GSL) biosynthesis as a key pathway fueled by glucose that enables CD8 T cell expansion and cytotoxic function . Using C-based stable isotope tracing, we demonstrate that CD8 effector T cells use glucose to synthesize uridine diphosphate-glucose (UDP-Glc), a precursor for glycogen, glycan, and GSL biosynthesis.

Functional overlap of inborn errors of immunity and metabolism genes defines T cell metabolic vulnerabilities.

Inborn errors of metabolism (IEMs) and immunity (IEIs) are Mendelian diseases in which complex phenotypes and patient rarity have limited clinical understanding. Whereas few genes have been annotated as contributing to both IEMs and IEIs, immunometabolic demands suggested greater functional overlap. Here, CRISPR screens tested IEM genes for immunologic roles and IEI genes for metabolic effects and found considerable previously unappreciated crossover.

A diverse proteome is present and enzymatically active in metabolite extracts.

Metabolite extraction is the critical first-step in metabolomics experiments, where it is generally regarded to inactivate and remove proteins. Here, arising from efforts to improve extraction conditions for polar metabolomics, we discover a proteomic landscape of over 1000 proteins within metabolite extracts. This is a ubiquitous feature across several common extraction and sample types.

NRF2-dependent regulation of the prostacyclin receptor PTGIR drives CD8 T cell exhaustion.

The progressive decline of CD8 T cell effector function-also known as terminal exhaustion-is a major contributor to immune evasion in cancer. Yet, the molecular mechanisms that drive CD8 T cell dysfunction remain poorly understood. Here, we report that the Kelch-like ECH-associated protein 1 (KEAP1)-Nuclear factor erythroid 2-related factor 2 (NRF2) signaling axis, which mediates cellular adaptations to oxidative stress, directly regulates CD8 T cell exhaustion.

C metabolite tracing reveals glutamine and acetate as critical in vivo fuels for CD8 T cells.

Infusion of C-labeled metabolites provides a gold standard for understanding the metabolic processes used by T cells during immune responses in vivo. Through infusion of C-labeled metabolites (glucose, glutamine, and acetate) in -infected mice, we demonstrate that CD8 T effector (Teff) cells use metabolites for specific pathways during specific phases of activation. Highly proliferative early Teff cells in vivo shunt glucose primarily toward nucleotide synthesis and leverage glutamine anaplerosis in the tricarboxylic acid (TCA) cycle to support adenosine triphosphate and de novo pyrimidine synthesis.

Lipid availability influences ferroptosis sensitivity in cancer cells by regulating polyunsaturated fatty acid trafficking.

Ferroptosis is a form of cell death caused by lipid peroxidation that is emerging as a target for cancer therapy, highlighting the need to identify factors that govern ferroptosis susceptibility. Lipid peroxidation occurs primarily on phospholipids containing polyunsaturated fatty acids (PUFAs). Here, we show that even though extracellular lipid limitation reduces cellular PUFA levels, lipid-starved cancer cells are paradoxically more sensitive to ferroptosis.

A noncanonical polyamine from bacteria antagonizes animal mitochondrial function.

Canonical polyamines such as agmatine, putrescine, and spermidine are evolutionarily conserved metabolites found in nearly all forms of life ranging from bacteria to humans. Recently, interactions between polyamines produced by gut bacteria and human intestinal cells have been proposed to contribute to both Irritable Bowel Syndrome with Diarrhea (IBS-D) and inflammatory bowel diseases. However, the molecular mechanisms that underlie these effects are often unclear due in part to limitations in the methods used to manipulate and study polyamine functions Here, we developed a based screening platform and a modified LC-MS approach for profiling polyamine metabolites.

Acod1 expression in cancer cells promotes immune evasion through the generation of inhibitory peptides.

Targeting programmed cell death protein 1 (PD-1) is an important component of many immune checkpoint blockade (ICB) therapeutic approaches. However, ICB is not an efficacious strategy in a variety of cancer types, in part due to immunosuppressive metabolites in the tumor microenvironment. Here, we find that αPD-1-resistant cancer cells produce abundant itaconate (ITA) due to enhanced levels of aconitate decarboxylase (Acod1).