bims-celmim Biomed News
on Cellular and mitochondrial metabolism
Issue of 2026–11–01
twenty-six papers selected by
Marc Segarra Mondejar, AINA



  1. Nature. 2026 Oct 28.
      
    Keywords:  Cell biology; Metabolism; Physiology
    DOI:  https://doi.org/10.1038/d41586-026-03261-2
  2. Sci Adv. 2026 Oct 30. 12(44): eaed1177
      Hypoxia-inducible factors (HIFs) are constitutively active in clear cell renal cell carcinoma (ccRCC) cells. Here, we investigated whether these cells could still respond to hypoxia independently of canonical HIF activation. We found that hypoxia provokes a NADH reductive stress that attenuates lactate release when the supply of extracellular pyruvate becomes limited, a response that was restored by the ectopic expression of the cytosolic and mitochondria-targeted NADH oxidase (LbNOX). Suppression of the mitochondrial electron transport chain (mtETC) alone is sufficient to attenuate glycolytic flux when extracellular pyruvate is limited, a situation consistent with metabolomic data from human ccRCCs. Furthermore, this response can be mimicked by pharmacological or genetic inhibition of mitochondrial complex IV (CIV) activity and restored by the mitochondrial-targeted alternative oxidase (AOX). Therefore, our data suggest that cells can respond to low oxygen tension through a mitochondrial-dependent elevation of NADH/NAD+, resulting in the suppression of glycolysis when pyruvate availability is compromised.
    DOI:  https://doi.org/10.1126/sciadv.aed1177
  3. Front Immunol. 2026 ;17 1939528
      Acute kidney injury (AKI) and chronic kidney disease (CKD) are common clinical disorders that have high incidence and mortality. Their pathogenesis and the mechanisms underlying AKI-to-CKD progression remain unclear. Metabolic reprogramming has emerged as a core mechanism driving the onset and progression of kidney diseases. Glutamine (Gln) metabolism, a central component of renal energy metabolism, not only maintains acid-base balance and cellular homeostasis but also actively participates in pathophysiological processes including ischemic injury, oxidative stress, inflammatory regulation and fibrosis. Multi-omics studies have revealed stage-specific alterations in Gln metabolism-associated signatures during kidney injury. In AKI, altered Gln levels and redox-related metabolites may suggest disturbances in metabolic pathways, whereas in CKD, elevated glutaminase 1 (GLS1) expression and glutaminolysis-associated metabolic reprogramming are associated with fibrosis. Gln, as an immunonutrient, also serves as a critical energy substrate to sustain the proliferation, activation, and effector functions of immune cells. Gln metabolism may reshape the immune microenvironment within the injured kidney, thereby modulating disease progression. Targeting the Gln metabolic axis may offer new therapeutic insights for AKI and CKD. However, the changes in Gln metabolism and its consequent immunometabolic effects during the AKI-to-CKD transition remain poorly understood. This narrative review aims to provide a comprehensive overview of the dynamic changes in Gln metabolism during acute and chronic kidney diseases, its stage-specific mechanisms, and its potential as a therapeutic target. We also seek to provide a theoretical basis for developing novel biomarkers and targeted therapies based on Gln metabolic reprogramming.
    Keywords:  acute kidney injury; chronic kidney disease; fibrosis; glutaminase 1; glutamine metabolic reprogramming; immunometabolism; inflammation
    DOI:  https://doi.org/10.3389/fimmu.2026.1939528
  4. Trends Cancer. 2026 Oct 30. pii: S2405-8033(26)00239-6. [Epub ahead of print]
      Advancements in in vivo stable isotope tracing have revolutionized our understanding of cancer metabolism, transitioning the field from static metabolomic snapshots to dynamic metabolic pathway activities. However, interpreting raw fractional enrichment data presents significant biological and analytical challenges. This review systematically examines the methodological landscape of in vivo tracing, addressing the interpretive gap created by clinical constraints, such as single-timepoint surgical sampling. We dissect how secondary circulating tracers and the inherent heterogeneity of the tumor microenvironment can confound metabolic signals. We highlight the critical transition to metabolic flux analysis as the requisite computational step to overcome these challenges and to identify targetable metabolic vulnerabilities in precision oncology.
    Keywords:  digital twins; in vivo isotope tracing; isotope tracing in patients; metabolic flux analysis; tumor heterogeneity; tumor metabolism
    DOI:  https://doi.org/10.1016/j.trecan.2026.10.005
  5. Front Neurol. 2026 ;17 1915238
       Background: Genetic factors are estimated to account for approximately 30-50% of the risk for developing Multiple sclerosis (MS). Distinct mitochondrial variants, impairments in the respiratory chain, and mitochondrial dysfunction have been reported in individuals affected by MS. Mitochondria and the endoplasmic reticulum (ER) form membrane contact sites (ERMCs) that control important biological functions. Dysregulated ERMCs have been associated with a number of severe consequences for homeostasis, including altered mitochondrial calcium levels, impaired ATP production and abnormal lipid transfer. All of these mechanisms are thought to play an important role in the pathogenesis and disease progression of MS. Here, we investigated the hypothesis that the mitochondrial predisposition plays a crucial role in contributing to MS development.
    Methods: Mitochondrial functionality was analyzed in a model of human induced primary neurons (iPNs), and neuronal precursor cells (NPCs), differentiated from induced pluripotent stem cells (iPSCs) from people with MS and healthy controls (HCs). Seahorse analysis was performed for investigation of the bioenergetic profile of the cells. ERMC and mitochondrial morphological analysis were carried out to investigate the potential impact of mitochondrial dysfunction in MS-derived neurons.
    Results: Seahorse analysis revealed significant differences in the respiratory complexes (spare capacity: p = 0.0002; non-mitochondrial oxygen consumption: p = 0.0207) and glycolysis (p = 0.0001; glycolytic reserve p = 0.0018) from MS-derived iPNs compared to HCs. We further investigated mitochondrial dysfunction in NPCs (maximal respiration p = 0.0491; non-mitochondrial oxygen consumption: p = 0.0226) and a significant difference in glycolytic reserve (p = 0.0359) from MS-derived NPC compared to HCs. Furthermore, we identified a significantly higher amount of ERMCs (p < 0.0001) and altered mitochondrial morphology in MS-derived iPNs compared to HC.
    Discussion: Our data are highlighting the importance of genetic mitochondrial contribution to MS pathology, by showing that MS-derived NPCs and iPNs exhibit altered mitochondrial behavior and morphology compared to healthy control (HC)-derived cells.
    Keywords:  endoplasmic reticulum; endoplasmic reticulum-mitochondria contacts; metabolism; mitochondria; multiple sclerosis
    DOI:  https://doi.org/10.3389/fneur.2026.1915238
  6. Proc Natl Acad Sci U S A. 2026 Nov 03. 123(44): e2602106123
      In neurons, the endoplasmic reticulum (ER) forms an extensive network that establishes membrane contact sites (MCSs) with various organelles including the plasma membrane (PM). While MCSs are known to regulate lipid exchange and Ca2+ signaling, their specific roles in synaptic transmission remain poorly understood. Here, we demonstrate that the ER-resident proteins VAPA and VAPB are essential for organizing presynaptic Ca2+ exchange and mobilizing synaptic vesicles. We show that the loss of VAP impairs Ca2+ loading into both the ER and mitochondria during electrical activity. This regulation occurs primarily through VAP interactions with voltage-gated potassium (Kv2) channels at the PM. Our data suggest that the Kv2-VAP complex organizes presynaptic Ca2+ signaling outside the active zone. Without this scaffold, vesicle mobilization for exocytosis is strongly impaired and a larger fraction remains trapped in the reserve pool. These findings reveal a role for Kv2-VAP MCSs in coordinating organelle Ca2+ signaling and the synaptic vesicle cycle.
    Keywords:  calcium; endoplasmic reticulum; presynaptic; synaptic transmission; vesicles
    DOI:  https://doi.org/10.1073/pnas.2602106123
  7. bioRxiv. 2026 Oct 07. pii: 2026.10.06.757085. [Epub ahead of print]
      Supratentorial ependymomas (ST-EPNs) are aggressive pediatric brain tumors predominantly driven by the recurrent ZFTA-RELA fusion, an oncogenic chromatin regulator that establishes an aberrant transcriptional program. Although metabolic pathways modulate epigenetic regulation by controlling the availability of metabolic cofactors, how ZFTA-RELA coordinates metabolic reprogramming with epigenetic regulation is not well understood. Here, we show that ZFTA-RELA-positive ependymomas exhibit enhanced methionine dependency, elevated adenosyl homocysteinase (AHCY) expression, and epigenetically control aspartate metabolism for tumor growth. Mechanistically, ZFTA-RELA upregulates AHCY, increasing cellular methylation potential which promotes H3K4me3-dependent expression of CAD, the first enzyme complex of de novo pyrimidine biosynthesis, while simultaneously enforcing H3K27me3 mediated repression of ASNS, which encodes asparagine synthetase. Through this coordinated epigenetic program, aspartate utilization is directed toward pyrimidine biosynthesis while endogenous asparagine production is limited. Restricting S-adenosylmethionine availability or genetically or pharmacologically inhibiting AHCY reverses these epigenetic states, leading to CAD downregulation, ASNS upregulation, impaired nucleotide synthesis, and suppression of tumor growth in vitro and in vivo. Similarly, EZH2 inhibition also restores ASNS expression and suppresses tumor proliferation. These findings suggest that ZFTA-RELA EPN maintain ASNS-low phenotype which conditionally make them dependent on extracellular asparagine. We further show that enhanced de novo pyrimidine synthesis not only supports nucleotide production but also provides UDP-sugars required for N-glycosylation and stabilization of the asparagine transporter SLC1A5, thereby promoting extracellular asparagine uptake and tumor proliferation. Collectively, our findings identify AHCY as a critical metabolic regulator of epigenetic and metabolic reprogramming that drives pyrimidine synthesis and establishes extracellular asparagine dependency, revealing actionable metabolic vulnerabilities in ZFTA-RELA-positive ST-EPNs.
    Abstract Figure:
    Key Findings: ZFTA-RELA fusion drives aspartate metabolic reprogramming through chromatin regulationAdenosylhomocysteinase (AHCY) epigenetically enhance de novo pyrimidine synthesis and suppress endogenous asparagine synthesis ZFTA-RELA EPNs exhibit ASNS low phenotype and dependence on extracellular asparagine Enhanced de novo pyrimidine biosynthesis fuels nucleotide synthesis and SLC1A5-dependent asparagine uptakeTargeting de novo pyrimidine biosynthesis and depleting extracellular asparagine reveal actionable vulnerabilities in ZFTA-RELA ST-EPN.
    DOI:  https://doi.org/10.64898/2026.10.06.757085
  8. Cell Commun Signal. 2026 Jul 29. pii: 577. [Epub ahead of print]24(1):
       BACKGROUND: Neutrophils, pivotal effector cells of the immune system, are increasingly recognized to have considerable functional and phenotypic heterogeneity. The emergence of immunometabolism has offered a framework for understanding this diversity. Accumulating evidence indicates that shifts in metabolic pathways and their byproducts can reshape the fate and function of neutrophils.
    MAIN BODY: Neutrophil heterogeneity arises from both distinct developmental stages and specific signals within peripheral tissue microenvironments. Functionally, glycolysis is the central metabolic pathway that fuels core effector responses, while metabolites such as lactate, lipids, and amino acids can further modulate neutrophil phenotypes. In pathological contexts of metabolic dysregulation, metabolic stress induces extensive reprogramming of neutrophils. This process drives the accumulation of specific metabolites, which in turn trigger transcriptional reprogramming through epigenetic remodeling, establishing a self-reinforcing loop that sustains pro-pathological neutrophil states. Targeting key nodes within these dysregulated metabolic pathways has potential as a therapeutic strategy.
    CONCLUSIONS: Here, we review the metabolic heterogeneity of neutrophil subpopulations and the mechanisms by which distinct metabolic programs drive disease progression in pathological settings. We further discuss current therapeutic strategies targeting these pathways. Through this analysis, we aim to provide a refined perspective on the immune landscape and to identify new possibilities for therapeutic intervention.
    Keywords:  Heterogeneity; Immunometabolism; Neutrophils; Transcriptomics; Tumor-associated neutrophils
    DOI:  https://doi.org/10.1186/s12964-026-03112-7
  9. Nat Commun. 2026 Sep 29. pii: 11215. [Epub ahead of print]17(1):
      During mitotic growth, Saccharomyces cerevisiae cells age by dividing asymmetrically, producing young daughter cells while retaining age-associated damage in the mother cell, which will eventually become senescent. Gametogenesis naturally and fully resets precursor cell lifespan, even for replicatively aged cells. However, the mechanisms responsible for gametogenic rejuvenation have remained mysterious. This is partly due to the existing methods to quantify lifespan resetting in this context, which are limited to low-throughput and labor-intensive approaches. Here, we introduce a high-throughput assay that allows systematic characterization of factors required for gametogenic rejuvenation. With this approach, we show that we can sensitively measure a wide range of gamete replicative lifespans that are consistent with established mutants. Excitingly, we also discover that Atg39 and Atg40, receptors involved in selective autophagy of the ER, are molecular determinants of gametogenic rejuvenation. This technique will enable systematic identification of the molecular factors that drive gametogenic rejuvenation.
    DOI:  https://doi.org/10.1038/s41467-026-77993-0
  10. bioRxiv. 2026 Sep 03. pii: 2026.09.01.748611. [Epub ahead of print]
      Maintenance of cellular homeostasis requires tight coordination between protein synthesis and degradation, particularly at old age and under conditions of stress including starvation. Autophagy contributes to sustain this balance by degrading cytoplasmic proteins and organelles. It thus is essential to prevent the accumulation of damaged proteins and organelles and to recycle nutrients. Of the three forms of autophagy, macroautophagy, chaperone mediated autophagy, and (endosomal) microautophagy (e-MI), the latter remains the least well understood. During e-MI, cytosolic substrate proteins are captured into late endosomes via ESCRT-dependent multivesicular body formation and then degraded in late endosomes or lysosomes. e-MI is thought to contribute to protein quality control under basal conditions and under stress. Importantly, very little is known about the endogenous substrates of e-MI in flies and thus about its physiological role. Performing integrative multi-omic analyses in Drosophila larval fat body that has functions similar to mammalian liver and adipose tissue, we identified 153 high-confidence endogenous e-MI substrates with the degradation of ribosomal proteins by e-MI being the most strongly affected functional category. Generally, we found that starvation caused the depletion of proteins involved in translation, aminoacyl-tRNA synthesis, and ribosomal biogenesis, without affecting their level of transcripts. Importantly, we observe a striking specificity between e-MI and macroautophagy, as the two pathways largely target distinct protein sets including different subsets of ribosomal proteins. Our metabolomic analysis further shows that genetic inhibition of e-MI reverses the reduced levels of amino acid caused by starvation. Together, our findings reveal ribosome turnover as a central physiological function of Drosophila e-MI and establish e-MI as a pathway driving metabolic adaptation during starvation.
    HIGHLIGHTS: Proteomic and metabolomic analysis of Drosophila fat body under starvation stress Systematic identification of endosomal microautophagy (e-MI) substrates.Ribosomal proteins are a major target of e-MI.e-MI and macroautophagy degrade distinct proteins incl. different ribosomal ones.Prolonged starvation alters amino acid levels.
    DOI:  https://doi.org/10.64898/2026.09.01.748611
  11. Nature. 2026 Oct 28.
      The heart possesses a dynamic capacity to oxidize a variety of fuels, including glucose and lactate, to meet its energetic demands under diverse dietary, exertion and injury stressors1. Oxidation of carbohydrate substrates is thought to converge on the cytosolic generation of pyruvate, which is transported by the mitochondrial pyruvate carrier (MPC) for entry into the tricarboxylic acid cycle2. Here we find that glucose-derived carbon is oxidized in mouse myocardium even when the MPC is genetically ablated. Using genetic and pharmacological tools, we demonstrate that lactate monocarboxylate transporter 1 (MCT1, encoded by Slc16a1) is required for the oxidation of glucose carbon by MPC-deficient myocardium. We further observe that MCT1, traditionally localized to the plasma membrane, also resides in the inner mitochondrial membrane of mouse and human cardiomyocytes. Together with matrix-localized LDHB, MCT1 enables mitochondrial lactate conversion to pyruvate and NADH, directly fueling the electron transport chain. Loss of MCT1 impairs lactate oxidation, disrupts metabolic flexibility and accelerates the development of heart failure with increased mortality after hyperactivation of the neurohormonal axis or ischemia-reperfusion injury. Thus, the existence of a parallel lactate-based pathway for carbohydrate oxidation can sustain cardiac energetics and maintain myocardial structure and function under diverse stress conditions.
    DOI:  https://doi.org/10.1038/s41586-026-11182-3
  12. Methods Mol Biol. 2027 ;3101 19-52
      Genetically encoded biosensors are GFP-based tools that can visualize the dynamics and spatial features of cellular processes. The design of a genetically encoded biosensor dictates the method that is used to measure the response. Common readouts use some sort of fluorescence intensity measurement, which is subject to both technical and biological perturbations, including sample drift, excitation power fluctuations, changes in sample size/volume, or a change in expression level. Yet, the fluorescence lifetime of a fluorophore is not affected by the aforementioned perturbations. Therefore, biosensors that respond with a large lifetime change offer a more robust method of detecting cellular processes. Here, we report on protocols for calcium imaging using fluorescence lifetime imaging microscopy (FLIM) to measure the response of a genetically encoded lifetime biosensor. The protocols include details on biosensor production and purification, calibration of purified biosensor with FLIM, introduction of the plasmid in HeLa and endothelial cells, and timelapse analysis of FLIM data. In this chapter, we use the green fluorescent biosensor G-Ca-FLITS as an example, but the protocols can be generally applied to biosensors with lifetime contrast.
    Keywords:  Bioimage analysis; Biosensor; Calcium; Endothelial cells; FLIM; GCaMP; Imaging
    DOI:  https://doi.org/10.1007/978-1-0716-5687-7_2
  13. Chem Biomed Imaging. 2026 Oct 26. 4(10): 2203-2215
      Neuronal metabolism is fundamental to brain functions and diseases, yet its spatial and temporal dynamics and interactions remain poorly understood. Here, we introduce a tandem deep-learning approach integrated with bioorthogonal chemical imaging using stimulated Raman scattering (SRS) microscopy. This method achieves high-speed and quantitative metabolic profiling in live neuronal cocultures. Our deep-learning framework consists of a recurrent convolutional neural network (RCNN) that enables high-resolution 3D imaging with minimal photodamage and a U-Net segmentation model for cell-type-specific metabolic analysis. Using deuterium-labeled metabolites, we demonstrate the ability to trace lipid, protein, glucose, and D2O metabolism in live neurons, astrocytes, and oligodendrocytes under physiological and pathological conditions, including NMDA receptor activation, proteasome inhibition, and Huntington's disease. Our findings reveal distinct metabolic adaptations among neuronal cell types and underscore the importance of noninvasive metabolic profiling for understanding neuronal interactions and disease mechanisms. This platform significantly advances live-cell dynamic imaging with broad applications in neuroscience, disease modeling, and therapeutic screening.
    Keywords:  3D cell segmentation; bioorthogonal imaging; deep learning reconstruction; live-cell metabolic imaging; neuronal metabolism; stimulated Raman scattering microscopy
    DOI:  https://doi.org/10.1021/cbmi.6c00011
  14. bioRxiv. 2026 Oct 11. pii: 2026.10.05.756890. [Epub ahead of print]
      SARM1 is an inducible NADase that executes pathological axon degeneration, but how NAD+ destruction causes neuronal failure remains unclear. Because SARM1 is predicted to act outside the mitochondrial matrix, cytosolic NAD+ loss has been viewed as the critical lethal lesion. We show that SARM1 activation rapidly depletes cytosolic and mitochondrial NAD+ and collapses ATP in both compartments, revealing early, coupled metabolic failure. Enhancing mitochondrial NAD+ import through SLC25A51, the mitochondrial NAD+ transporter, preserves mitochondrial NAD+, maintains mitochondrial function, and delays axon degeneration and neuronal death despite ongoing SARM1 activity. Unexpectedly, SLC25A51 restores cytosolic NAD+-dependent metabolism, reversing a glycolytic block and increasing NAD+ synthesis during stress. Glycolytic inhibition attenuates protection, identifying cytosolic metabolic recovery as an important component of neuronal resilience. AAV-SLC25A51 improves function in a chronic SARM1-dependent neuropathy model. Thus, mitochondrial NAD+ import gates SARM1-driven degeneration by limiting coupled mitochondrial-cytosolic metabolic failure, presenting a downstream intervention point for axon preservation.
    DOI:  https://doi.org/10.64898/2026.10.05.756890
  15. PLoS One. 2026 ;21(10): e0361332
      Sepsis‑associated acute kidney injury (S‑AKI) is a major cause of morbidity and mortality in critically ill patients, yet effective targeted therapies remain lacking due to an incomplete understanding of its pathogenesis. Ferroptosis, an iron‑dependent form of regulated cell death driven by lipid peroxidation, has recently been implicated in AKI, but the upstream regulators of this process in sepsis remain undefined. Here, we identify SIRT5, a mitochondrial NAD ⁺ ‑dependent desuccinylase, as a critical endogenous suppressor of ferroptosis in S‑AKI. Using a cecal ligation and puncture (CLP) murine model and lipopolysaccharide (LPS)‑stimulated HK‑2 proximal tubular cells, we show that SIRT5 expression is significantly downregulated in septic kidney injury. Renal tubular‑specific ablation of Sirt5 exacerbated CLP‑induced renal dysfunction, structural damage, and tubular cell death, whereas AAV9‑mediated SIRT5 overexpression attenuated these pathological changes. Mechanistically, SIRT5 deficiency tipped the balance of the ACSL4/FTH1 axis toward ferroptosis: it increased ACSL4‑dependent membrane lipid remodeling and reduced FTH1‑mediated iron sequestration, accompanied by suppression of the antioxidant enzyme GPX4. Consequently, lipid peroxidation, iron overload, and mitochondrial damage were markedly amplified. Notably, knockdown of ACSL4 in SIRT5‑deficient HK‑2 cells effectively reversed lipid peroxidation, iron accumulation, and cell death, establishing ACSL4 as a key downstream effector of SIRT5‑mediated ferroptosis suppression. Our findings reveal a previously unrecognized SIRT5-ACSL4/FTH1 regulatory axis that governs ferroptotic susceptibility in renal tubular cells during sepsis, and suggest that pharmacological restoration of SIRT5 activity or blockade of ACSL4‑driven ferroptosis may offer novel therapeutic avenues for S‑AKI.
    DOI:  https://doi.org/10.1371/journal.pone.0361332
  16. Elife. 2026 Oct 29. pii: RP107627. [Epub ahead of print]14
      The proliferation and development of activated B lymphocytes into antibody (Ab)-secreting plasma cells are critical determinants of humoral immunity and sustain certain autoimmune diseases. Specific pathways and substrate supplies in intermediary metabolism influence lymphocyte differentiation and function. We now show that although stringent restriction of glutamine supply decreases B cell proliferation and differentiation into plasma cells, glutaminolysis - a major metabolic use of this amino acid - was only conditionally crucial in B cells and the Ab responses derived from them. Gls, the gene encoding the main glutaminase of lymphocytes, promoted anti-NP Ab responses at the primary and recall phases if either glucose uptake into mouse B cells or pyruvate into their mitochondria was also impaired. Otherwise, it was dispensable. This synthetic auxotrophy, that is, the conditional requirement of glutaminase for processes in addition to survival, involved supporting progressive expansion of mitochondrial respiration followed by plasma cell differentiation. Surprisingly, impairment of glutaminase and the mitochondrial pyruvate channel decreased IL-21 stimulation of STAT3 phosphorylation as well as interferon stimulation of STAT1 activation. Together, our findings establish a powerful collaboration of metabolic pathways in programming increased respiration and the development of Ab-secreting cells, but also reveal modulation of cytokine receptor signaling by metabolism.
    Keywords:  B lymphocyte; cytokine receptor signaling; immunology; immunometabolism; inflammation; mitochondria; mouse; plasma cell; regulation of antibodies
    DOI:  https://doi.org/10.7554/eLife.107627
  17. Biochim Biophys Acta Mol Cell Res. 2026 Oct 30. pii: S0167-4889(26)00142-4. [Epub ahead of print] 120243
      Endogenous myocardial succinate accretion induces oxidative distress on a massive scale by triggering a drastic spike in hydrogen peroxide (H2O2) production. Here, using the H9C2 rat cardiomyocyte cell line, we demonstrate for the first time that the import of exogenous succinate by cardiomyocytes fuels H2O2 generation through the pH-gated monocarboxylate transporter 1 (MCT1, aka SLC16A1). Succinate as a fuel depended on a slightly acidic extracellular medium (pH < 7.0), whereas exogenous succinate could not be metabolized at physiological neutrality. AZD3965 (1 μM), a highly specific MCT1 inhibitor, strongly prevented uptake of isotopically labeled succinate and its metabolism to other TCA cycle intermediates. Physiologically relevant succinate levels (50 μM) fueled both H2O2 production and oxidative phosphorylation (OxPhos), which inhibited by complex II inhibitor dimethylmalonate (DMM) or AZD3965. By contrast, pathological succinate (100 μM) increased H2O2 production, which was also sensitive to DMM and AZD3965 inhibition. Treating cells with succinate (1 mM), which reflects the concentration observed in the ischemic heart, induced H2O2 production and collapsed the mitochondrial membrane potential. In sum, our experiments show for the first time extracellular succinate fuels H2O2 biogenesis in H9C2 cardiomyocytes after its import by MCT1. These results provide new insights into how a pathological extracellular succinate buildup can trigger cardiovascular complications by promoting H2O2 production by mitochondrial RET in cardiomyocytes.
    DOI:  https://doi.org/10.1016/j.bbamcr.2026.120243
  18. Chem Biomed Imaging. 2026 Oct 26. 4(10): 2226-2245
      Quantitative organelle analysis is highly sensitive to image-processing choices, limiting reproducibility across microscopy studies. Here, we systematically compare automated, interactive machine learning, and deep learning-based pipelines for lipid droplet and mitochondrial quantification in live human osteosarcoma cells imaged by fluorescence microscopy and label-free holotomography. Using standardized downstream feature extraction, we evaluated script-based workflows (Fiji, Python), a modular platform (CellProfiler), interactive machine learning (ilastik), and pretrained deep learning models. Lipid droplet segmentation was qualitatively consistent across approaches; however, droplet counts, and size distributions varied substantially between pipelines and imaging modalities, with ilastik reducing background-driven detections and improving cross-modality agreement. In contrast, mitochondrial quantification proved highly sensitive to segmentation and skeletonization choices, particularly in holotomography where global intensity-threshold-based methods failed to capture network structure. Based on these cross-pipeline comparisons, we demonstrate how organelle- and modality-specific benchmarking can guide pipeline selection, illustrated by the analysis of metabolic perturbations affecting lipid droplets and mitochondria. Together, these results highlight modality- and morphology-dependent limitations in common analysis pipelines and provide practical guidance for selecting robust, reproducible strategies for quantitative organelle imaging.
    Keywords:  fluorescence microscopy; holotomography; image analysis pipelines; lipid droplets; machine learning segmentation; mitochondria; organelle quantification
    DOI:  https://doi.org/10.1021/cbmi.6c00038
  19. Cancer Res. 2026 Oct 27.
      Metabolic reprogramming is a well-described hallmark of clear cell renal cell carcinoma (ccRCC). Gene copy number variation and altered gene expression data suggest enhanced branched-chain amino acid (BCAA) transamination and reduced BCAA oxidation are highly selected traits in ccRCC. Surprisingly, we found that genetic modulation of BCAA oxidation had little effect on experimental ccRCC cell growth in vitro and in vivo. In contrast, BCAA transamination in ccRCC cells was essential for the generation of glutamate-derived glutathione and cell viability when glutamine was limiting. Thus, BCAA transamination conferred resistance to states of low glutamine or treatment with the glutaminase inhibitor CB-839 by providing glutathione independent of glutamine breakdown. Targeting BCAA transamination in vitro and in vivo sensitized ccRCC to CB-839 mediated glutaminase inhibition by decreasing glutathione biosynthesis and redox homeostasis. These findings reveal that BCAA transamination maintains critical glutamate and glutathione levels in glutamine-deprived ccRCC, explaining why CB-839 treatment has been ineffective in ccRCC clinical trials and demonstrate an approach to treat ccRCC by targeting BCAA transamination to create a vulnerability to glutaminase inhibition.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-26-0563
  20. Nat Chem Biol. 2026 Oct 28.
      Excessive nicotinamide adenine dinucleotide (NAD+) consumption fuels neurological pathogenesis, yet the limited benefit of NAD+ supplementation hints at unresolved toxicity from its catabolism. Here, we identify ADP-ribose, a neglected NAD+ catabolite generated by poly(ADP-ribose) polymerase 1 (PARP1) and poly(ADP-ribose) glycohydrolase, as an inducer of neuronal ferroptosis through nucleotide metabolic rewiring. We discovered that extracellular ADP-ribose directly binds and inhibits the nucleoside transporter equilibrative nucleoside transporter 2 (ENT2; SLC29A2), suppressing nucleotide salvage and driving compensatory hyperactivation of de novo purine and pyrimidine biosynthesis. This metabolic rerouting engages xanthine oxidase (XO) and dihydroorotate dehydrogenase (DHODH) to unleash superoxide bursts, triggering lipid peroxidation and ferroptotic neuronal death. ADP-ribose accumulates across neurological disease models and its acute administration recapitulates ferroptotic neurodegeneration in vivo. Targeting ADP-ribose signaling through PARP1 knockdown, NUDT9-mediated hydrolysis or dual XO/DHODH inhibition rescues delayed cognitive deficits in intracerebral hemorrhage models. These findings define the ADP-ribose-ENT2 axis as a metabolic driver of neuronal ferroptosis and reveal a druggable vulnerability in disorders marked by NAD+ hyperconsumption.
    DOI:  https://doi.org/10.1038/s41589-026-02355-2
  21. bioRxiv. 2026 Oct 06. pii: 2026.10.06.738500. [Epub ahead of print]
      Bone loss and metabolic dysregulation often coexist in older adults, yet the relationship between age-related changes in bone cell metabolism and bone-forming activity remains unclear. By modeling both conditions in aged mice and using in vivo stable-isotope tracing, we demonstrated that age-related decline in bone formation was coupled with an intrinsic impairment of glycolysis within bone tissue. Impaired glycolysis was associated with reduced protein levels of key glycolysis enzymes, and transcriptomics analyses revealed compensatory upregulation of glycolysis genes in aged bone. Metabolic intervention through long-term caloric restriction prevented age-related trabecular bone loss. Furthermore, osteoblast-specific genetic enhancement of glycolysis-via overexpression of HIF1α or the rate-limiting enzyme PFKFB3-significantly improved osteoblast function and increased bone mass in aged mice. Together, the study identifies glycolytic decline as a cell-autonomous driver of osteoblast deficiency and provides proof of principle that reactivating glycolysis can promote bone accrual in aging.
    DOI:  https://doi.org/10.64898/2026.10.06.738500
  22. Cell Rep. 2026 Oct 26. pii: S2211-1247(26)01303-3. [Epub ahead of print]45(11): 118224
      How cells integrate nutrient availability to coordinate metabolism and growth remains poorly understood. Here, we identify branched-chain amino acid (BCAA) synthesis as a metabolic sensing system linking mitochondrial activity to translational and transcriptional control. Yeast limits Leu and Val import and instead relies on their synthesis, allowing BCAA production to reflect mitochondrial anabolic capacity. Reduced Val synthesis activates Gcn2, whereas reduced Leu synthesis inhibits TORC1, together decreasing translation efficiency and restricting growth. This response lowers levels of the transcriptional repressor Mig1, suppressing the Warburg/Crabtree effect and promoting alternative carbon source utilization. Remarkably, pharmacological inhibition of Leu/Val synthesis induces this metabolic reprogramming even in nutrient-rich medium, indicating that mitochondrial BCAA synthesis can partially override other nutrient-sensing pathways. Thus, BCAA synthesis couples mitochondrial anabolic capacity to Gcn2 and TORC1 activity and, through translational control of transcription factor abundance, shapes cellular metabolism.
    Keywords:  CP: metabolism; Gcn2; TORC1; Warburg effect; amino acid synthesis; diauxic shift; mitochondria; starvation
    DOI:  https://doi.org/10.1016/j.celrep.2026.118224
  23. EMBO Rep. 2026 Oct 28.
      The branched chain amino acids (BCAAs: leucine, isoleucine, valine) are essential amino acids that function as catabolic substrates and signaling molecules via mTORC1. While individual BCAAs have unique roles in organismal and cellular physiology, the mechanisms underlying their individual effects remain poorly understood. We demonstrate that the three BCAAs have distinct roles in T cell biology. We find that isoleucine and valine are necessary and sufficient for quiescence exit and cell division, whereas leucine is dispensable. Mechanistically, these effects are independent of their diverging catabolic fates and instead due to differential sensing of leucine and isoleucine/valine by mTOR and c-Myc. While isoleucine and valine are necessary and sufficient for c-Myc expression, mTORC1 leucine-sensing represses c-Myc and proliferation during BCAA restriction. Together, we find that the discrete sensing of the BCAAs uncouples two major anabolic regulators, mTORC1 and c-Myc, in cell growth. This provides mechanistic insight into the distinct roles of the BCAAs in cell physiology, highlighting divergent BCAA sensing rather than catabolism, and offering a new lens to appreciate their impact on immunity and pathophysiology.
    DOI:  https://doi.org/10.1038/s44319-026-00919-w
  24. bioRxiv. 2026 Oct 05. pii: 2026.10.02.756141. [Epub ahead of print]
      Extracellular L-lactate reports cellular metabolism, but resolving its dynamics alongside intracellular metabolism and neuronal activity remains challenging. Here we develop eLACCO3 and R-eLACCO3, green and red cell-surface lactate biosensors with Ca 2+ -independent responses and faster response and recovery kinetics in cultured cells. Selected variants provide larger fluorescence responses than their predecessors in brain cells, slices, and living mice and improve detection of glucose-evoked extracellular lactate oscillations. Combining R-eLACCO3 with GCaMP6f enabled imaging of extracellular L-lactate simultaneously with odor-evoked activity in anesthetized mice and cortical activity in awake mice. These biosensors enable multiplexed measurements of extracellular lactate dynamics in relation to intracellular metabolism and neuronal activity.
    DOI:  https://doi.org/10.64898/2026.10.02.756141
  25. Methods. 2026 Oct 24. pii: S1046-2023(26)00214-8. [Epub ahead of print]257 14-24
      Cancer cells often exhibit elevated glycolysis even when oxygen is available, a phenomenon known as the Warburg effect and a potential therapeutic target. Three-dimensional (3D) cell culture systems mimic tumor masses, but whether cancer cells cultured in 3D retain this glycolytic dependence remains unclear. This study examined changes in metabolic pathway dependence using small-molecule inhibitors of glycolysis and mitochondrial ATP synthesis as an indirect approach, and investigated effects of metformin, an emerging antitumor metabolism drug, in a hepatocellular carcinoma cell line. Human hepatocellular carcinoma G2 (HepG2) cells were cultured as hemispherical aggregates. Following metformin pretreatment, small-molecule inhibitors targeting glycolysis, the tricarboxylic acid cycle, and mitochondrial ATP synthesis were applied. After metformin treatment, ATP levels were significantly decreased in the 2D monolayers, whereas ATP levels were unchanged in the 3D hemispheroids. Following the addition of small-molecule inhibitors, glucose dependence of HepG2 monolayers and hemispheroids remained unchanged compared with the vehicle control. In addition, inhibition of mitochondrial ATP synthase did not significantly reduce ATP levels in the 3D configuration. Overall, HepG2 cells in hemispheroids remained glucose-dependent for ATP production, although ATP response to metformin was reduced. Therefore, using 3D spheroids to test anti-Warburg drugs requires careful interpretation, considering different metabolic responses compared with 2D monolayers. Direct flux analysis is needed to further evaluate metabolic pathway dependence.
    Keywords:  ATP; Cancer cell line; Hepatoma carcinoma HepG2 cell; Spheroid; Warburg effect
    DOI:  https://doi.org/10.1016/j.ymeth.2026.10.009