Biology subjects

Chandel, N. S.

Publications and source records attributed to Chandel, N. S..

At least 19 recordsLinked to original sources

bioRxiv2026

2-Hydroxyglutarate Redirects Fatty Acid Partitioning to Mitigate Lipotoxic Stress and Preserve Metabolic Fuel

The role of 2-hydroxyglutarate in lipid metabolism is currently unknown. Here we show that 2HG redistributes the partitioning of fatty acids into triglyceride storage and away from membrane phospholipid synthesis, mitochondrial oxidation, and lipotoxic intermediates. In primary human cardiac and vascular cells, both enantiomers, D2HG and L2HG, expanded triglyceride stores and lipid droplets while selectively depleting phosphatidylethanolamine, with L2HG acting more potently than D2HG despite lower intracellular accumulation. Mechanistically, L2HG increases DGAT-dependent triglyceride synthesis, slows triglyceride turnover, and constrains the ethanolamine branch of the Kennedy pathway. This response limits fatty acid oxidation, long-chain acylcarnitine accumulation, and lipid peroxidation independently of pseudohypoxic transcription or canonical lipid storage regulators, while also remodeling the phosphoproteome and redox proteome. L2HG accumulation induces hypertriglyceridemia in mice, redistributes the acyl chain composition of cardiac triglycerides, and limits ischemia-induced acylcarnitine accumulation in the heart, mirroring a positive association between circulating 2HG and triglycerides in humans. Thus, 2HG expands metabolic flexibility from whether fatty acids are used as fuel to how that fuel is allocated among storage, membrane synthesis, and oxidation.

cell biology↗

bioRxiv2026

A multi-organ spatial metabolomic atlas of exercising mice reveals neuronal Complex I as a convergent and sufficient axis for tau pathology reduction in PS19

We constructed a spatially resolved metabolomic atlas of long-term exercise across six major organs in wild-type mice: brain, heart, lung, liver, kidney, and skeletal muscle, cataloguing 224 metabolic features and revealing coordinated inter-organ remodeling. Surprisingly, the brain showed particularly pronounced region-specific adaptation. Because pathological tau associates with synaptic mitochondria from early stages of tauopathy, we extended this multi-organ spatial metabolomic approach to PS19 mice and found that exercise reduced over 70% of observable tau pathology in PS19 hippocampus and restored the mitochondrial-related metabolome. Integrated proteomic and spatial metabolomic analyses identified NADH dehydrogenase Complex I as the convergent node. To test this finding biologically, we expressed the yeast NADH dehydrogenase, Ndi1, in PS19 neurons in the absence of exercise. This increased cerebral antioxidants, restored shuttle-linked metabolites, and reduced tau pathology. Increasing NADH dehydrogenase activity through NDI1 reproduces the core anti-tau and metabolic effects of exercise. These findings provide a molecular mechanism for how exercise may prevent or slow tau pathology accumulation, complementing the human-cohort literature linking exercise to delayed cognitive decline.

neuroscience↗

bioRxiv2026

Metabolic Coherence of the Mouse Brain

The brains metabolic demands are well established, but how metabolism is coordinated across anatomically distinct regions remains poorly understood. Here, using matrix-assisted laser desorption/ionization (MALDI) imaging integrated with the Allen Brain Atlas and optimal transport-based computational analysis, we map the spatial metabolome across twelve major mouse brain divisions. We define an optimal-transport-derived inter-regional metabolite similarity metric and refer to it as metabolic coherence. This structure is largely preserved in an amyloid mouse model of Alzheimers disease despite widespread changes in individual metabolite and lipid levels. Individual metabolites and lipids shift in a coordinated manner across regions, sustaining inter-regional relationships even as absolute levels change in patterns indicative of mitochondrial dysfunction. To test whether the coherence metric is responsive to local intervention, we targeted the left hippocampus of mice from this model via lentiviral shHIF1 knockdown or neuronal AAV-mediated AOX expression. Both interventions were associated with metabolite normalization at the injection site. More importantly, normalization extended across distal regions sharing high metabolic similarity with the hippocampus and was accompanied by improved social memory in a single behavioral assay. Gene modulation and amyloid plaque reduction localized to the injection site.

neuroscience↗

bioRxiv2026

Mitochondrial ATP production promotes T cell differentiation and function by regulating chromatin accessibility

Immune elimination of chronic infection or cancer requires cytotoxic CD8+ T cells that adopt and maintain an effector phenotype. Cytotoxic T cell function is a bioenergetically demanding process and T cells subjected to chronic antigen exposure have compromised effector function despite high rates of glycolysis. Here we report the ability of the short-chain -hydroxy acid, D--hydroxybutyrate, to act as a signaling molecule that increases mitochondrial ATP production and drives the conversion of proliferating T cells into cytotoxic effector cells. DAHB signaling switches ATP production from glycolysis to oxidative phosphorylation supported by fatty acid oxidation, even in glucose-replete media. This conversion suppresses both AMPK phosphorylation and the integrated stress response (ISR) in activated T cells while significantly elevating the level of the phosphagen, phosphocreatine (PCr). Both the PCr bioenergetic reserve and oxidative phosphorylation were required for T cell effector differentiation. DAHB-induction of CD8-effector gene transcription was coupled to bioenergetics by enhanced ATP-dependent remodeling of chromatin accessibility at effector gene loci. DAHB enhanced CD8+ T cell antitumor activity both in vitro and in vivo, and DAHB treatment of transferred T cells led to persistent in vivo antitumor effects. Together, these findings link cellular bioenergetics to the regulation of chromatin accessibility and gene expression required to support effector function.

immunology↗

bioRxiv2025

Influenza A infection accelerates disease-associated microglia formation during physiological aging

Severe pneumonia is associated with an increased risk of cognitive decline and dementia, particularly in the elderly. Changes in microglia, the most abundant immune cell population in the brain, are also associated with cognitive decline and dementia, including the emergence of a transcriptional cell state referred to as disease-associated microglia (DAM). We sought to test the hypothesis that non-neuroinvasive influenza A virus (IAV) pneumonia results in transcriptional responses in brain microglia that drive premature expansion of DAM. Using bulk and single-cell RNA-sequencing, metabolomics, and spatial transcriptomics, we profiled neuroimmune populations in young, middle-aged, and old male mice during IAV infection and recovery. We observed an increased abundance of DAM, interferon-responsive microglia (IRM), CD4+ T cells, and CD8+ T cells in white matter regions beginning in middle age and persisting in old animals, irrespective of IAV infection. DAM exhibited a metabolic shift toward aerobic glycolysis with disrupted TCA cycling, citrulline depletion, and an elevated itaconate/-ketoglutarate ratio. Spatial transcriptomic profiling of the human middle frontal gyrus (MFG) in normal agers, SuperAgers, and patients with dementia revealed an analogous accumulation of DAM and CD8+ T cells in white matter. IAV pneumonia induced a transient immunosenescent-like response in microglia, marked by glucocorticoid-responsive gene expression and Ccnd3 upregulation. In response to IAV pneumonia, DAM expanded in middle-aged mice, whereas old mice were elevated at baseline and were largely unaffected by IAV infection. The age-related expansion of DAM was unaffected by pharmacological depletion and repopulation of microglia with a CSF1R antagonist or genetic gain or loss of function of the phagocytic receptor MERTK, suggesting the DAM phenotype is driven by the CNS microenvironment, rather than cell-intrinsic mechanisms. Our findings suggest that IAV pneumonia induces an acute immunosenescence response in microglia and accelerates the age-dependent expansion of DAM in white matter.

neuroscience↗

bioRxiv2025

NADH dehydrogenase reverses dietary and clock metabolic syndrome

Circadian clocks are internal timing systems that enable organisms to anticipate and adapt to daily environmental changes. These rhythms arise from a transcription-translation feedback loop in which CLOCK/BMAL1 regulate the expression of thousands of genes, including their repressors PER/CRY1. Disruption of circadian rhythms contributes to obesity, metabolic disease, and cancer2-4, yet how the clock maintains metabolic homeostasis remains limited. Here we report that the clock regulates oxidative metabolism through diurnal respiration of mitochondrial respiratory chain complex I. Genetic loss of the clock and high fat diet feeding in male mice led to reduced complex I respiration within adipocytes, leading to suppression of PPAR and insulin signaling pathways. In contrast, preserving complex I function maintained adipogenic and metabolic gene networks and protected against diet- and circadian-induced metabolic dysfunction independently of weight gain. These findings reveal that circadian disruption impairs metabolic health through mitochondrial complex I dysfunction, establishing clock control of complex I as a key regulator of transcriptional and metabolic homeostasis.

cell biology↗

bioRxiv2025

Aspartate transaminases are required for blood development

Red blood cells (RBCs) have a limited lifespan of approximately 120 days. This necessitates continuous RBC production, resulting in [~]200 billion new RBCs made per day to maintain oxygen delivery. Despite this enormous biosynthetic demand, the metabolic pathways supporting erythropoiesis are poorly understood. We profiled metabolites across four independent models of elevated erythropoiesis and a consistent increase in aspartate levels emerged when compared to controls. This suggested a potential role for aspartate metabolism in RBC production. To test this, we deleted the aspartate aminotransferases Got1 or Got2 globally or in an erythroid-specific manner. Loss of either enzyme resulted in anemia, with Got2 deficiency producing a more severe phenotype. Individual loss of either Got or dual Got deletion led to an erythroid defect, where early progenitors accumulated. In human and mouse models of erythropoiesis, GOT1 and GOT2 loss had opposing impacts on aspartate despite exhibiting similar anemic phenotypes, suggesting an aspartate-independent function for these enzymes. GOT1 and GOT2 are also components of the malate-aspartate shuttle (MAS), which regulates NAD(H) homeostasis. However, conditional deletion of another MAS enzyme, Mdh1, did not cause anemia, and alleviating NADH reductive stress in GOT2-deficient cells with cytoplasmic bacterial NADH oxidase (LbNOX) failed to restore erythropoiesis. Instead, transcriptomic and epigenetic analyses revealed dysregulation of chromatin histone modifications in GOT-deficient erythroid cells, implicating epigenetic dysfunction as a driver of defective erythropoiesis. Collectively, these findings identify a previously unrecognized role for GOT1 and GOT2 as a central link between metabolism and epigenetic regulation during erythroid development. These insights may inform the development of new therapeutic strategies for anemia.

biochemistry↗

bioRxiv2025

G1 and G2 ApolipoproteinL1 modulate macrophage inflammation and lipid accumulation through the polyamine pathway

The G1 and G2 variants of the gene encoding Apolipoprotein L1 (APOL1) increase risk for kidney disease and cardiometabolic traits. While previous studies have elucidated key mechanisms by which G1 and G2 APOL1 cause cellular inflammation and cytotoxicity, it remains unclear whether these mechanisms drive inflammation in G1 and G2 macrophages. In this study, we used mouse bone-marrow-derived macrophages and human induced pluripotent stem cell-derived macrophages to identify altered immune signaling and inflammatory activation caused by G1 and G2 APOL1. We demonstrated that G1 and G2 APOL1 increased lipid accumulation, pro-inflammatory cytokine expression, and inflammasome signaling; this inflammatory response was sustained when treated with anti-inflammatory cytokines IL-4 and IL-10. Additionally, in G1 and G2 macrophages we observed increased mitochondrial size and elongation, oxidative phosphorylation, and glycolysis. Finally, we used unbiased metabolite analysis to identify an accumulation of polyamine spermidine and the enrichment of the spermidine synthesis pathway in G1 and G2 macrophages. When treated with polyamine inhibitor -difluoromethylornithine (DFMO), lipid accumulation and inflammasome gene expression decreased in G1 and G2 macrophages. Together, these findings establish the pro-inflammatory effects of G1 and G2 APOL1 in macrophages and identify a novel pathway which ameliorates G1 and G2 effects on cellular inflammation.

cell biology↗

bioRxiv2025

Genetic modulation of mitochondrial NAD+ regeneration does not prevent dopaminergic neuron dysfunction caused by mitochondrial complex I impairment

Dysfunction of mitochondrial complex I (MCI) has been implicated in the degeneration of dopaminergic neurons in Parkinsons disease. Here, we report the effect of expressing MitoLbNOX, a mitochondrial-targeted version of the bacterial enzyme LbNOX, which increases regeneration of NAD+ in the mitochondria to maintain the NAD+/NADH ratio, in dopaminergic neurons with impaired MCI (MCI-Park mice). MitoLbNOX expression did not ameliorate the cellular or behavioral deficits observed in MCI-Park mice, suggesting that alteration of the mitochondrial NAD+/NADH ratio alone is not sufficient to compensate for loss of MCI function in dopaminergic neurons.

cell biology↗

bioRxiv2025

Endothelial Prolyl Hydroxylase 3 Mitigates Maladaptive Inflammation to Promote Post-Ischemic Kidney Repair

Acute kidney injury (AKI) is a major health concern and well-established risk factor for the development of chronic kidney disease (CKD). Tissue hypoxia is a prominent feature of the injured kidney that shapes the biological behavior of parenchymal and immune cells. Endothelial cells have important immunomodulatory roles, but the impact of dysregulated oxygen sensing on their responses remains poorly understood. By leveraging a combination of conditional mouse strains, single-cell analyses of mouse and human samples, and in vitro experiments, we demonstrate that the oxygen sensor PHD3 in the endothelium suppresses maladaptive inflammatory responses, thereby promoting kidney repair. Specifically, post-ischemic inactivation of endothelial PHD3, but not PHD1, leads to maladaptive kidney repair, characterized by increased fibrosis and inflammation. scRNA-seq analysis of the postischemic endothelial PHD3-haplodeficient kidney shows an endothelial IFN-{gamma} gene signature, resembling the responses seen in patients with severe AKI. By performing loss- and gain-of-function experiments in vitro, we demonstrate that PHD3 regulates IFN-{gamma} responsive pro-inflammatory signatures in a HIF-dependent manner. Consistent with this, simultaneous deletion of ARNT in endothelial PHD3-deficient mice restored kidney repair. Thus, our findings provide novel mechanistic insights into endothelial oxygen sensing and the AKI-to-CKD transition, highlighting potential therapeutic avenues for mitigating disease progression. TRANSLATIONAL STATEMENTUsing a genetic approach, we identified endothelial PHD3 as a critical regulator of kidney repair. Post-ischemic loss of endothelial PHD3--but not PHD1--led to maladaptive outcomes marked by increased injury, fibrosis, and inflammation. Mechanistically, we show that PHD3 restrains IFN-{gamma}-driven pro-inflammatory signaling through a HIF-dependent pathway. These findings reveal a central role for endothelial oxygen sensing in dictating kidney recovery and underscore the importance of cellular context in responses to hypoxia. Given the expanding clinical use of non-selective PHD inhibitors, our work highlights the need for more targeted, cell-specific approaches to modulate hypoxia pathways in kidney disease.

molecular biology↗

bioRxiv2025

Microglial Fructose Metabolism Is Essential for Glioblastoma Growth

Glioblastoma (GBM) is most common and aggressive primary brain tumor in adults, for which standard of care hasnt changed in twenty years. GBM tumor associated macrophages (TAMCs), consisting of infiltrating myeloid cells from the periphery and resident microglia cells, are pro-tumorigenic, promoting tumor growth. Fructose is one of the most abundant metabolites in the GBM tumor microenvironment (TME), as well as in the healthy central nervous system (CNS). In the CNS and GBM, microglia are the predominant expressors of the fructose transporter GLUT5. Mice lacking the GLUT5 transporter (GLUT5-KO) survive significantly longer after orthotopic implantation of two glioma cell lines than wildtype mice, which is not due to dietary fructose or peripherally derived TAMCs. Investigation of the TME showed that GLUT5-KO mice have more highly activated and inflammatory innate and adaptive immune compartments. Microglia cultured in fructose have a decreased phagocytic ability and exhibit decreased inflammatory capacity due to the polyol pathway promoting redox homeostasis.

cancer biology↗

bioRxiv2025

Pathway Coessentiality Mapping Reveals Complex II is Required for de novo Purine Biosynthesis in Acute Myeloid Leukemia

Understanding how cellular pathways interact is crucial for treating complex diseases like cancer, yet our ability to map these connections systematically remains limited. Individual gene-gene interaction studies have provided insights1,2, but they miss the emergent properties of pathways working together. To address this challenge, we developed a multi-gene approach to pathway mapping and applied it to CRISPR data from the Cancer Dependency Map3. Our analysis of the electron transport chain revealed certain blood cancers, including acute myeloid leukemia (AML), depend on an unexpected link between Complex II and purine metabolism. Through stable isotope metabolomic tracing, we found that Complex II directly supports de novo purine biosynthesis and exogenous purines rescue AML from Complex II inhibition. The mechanism involves a metabolic circuit where glutamine provides nitrogen to build the purine ring, producing glutamate that Complex II must oxidize to sustain purine synthesis. This connection translated to a metabolic vulnerability whereby increasing intracellular glutamate levels suppresses purine production and sensitizes AML to Complex II inhibition. In mouse models, targeting Complex II triggered rapid disease regression and extended survival in aggressive AML. The clinical relevance of this pathway emerged in human studies, where higher Complex II gene expression correlates with both resistance to mitochondria-targeted therapies and worse survival outcomes specifically in AML patients. These findings establish Complex II as a central regulator of de novo purine biosynthesis and identify it as a promising therapeutic target in AML.

cancer biology↗

bioRxiv2025

Tissue-resident skeletal muscle macrophages promote recovery from viral pneumonia-induced sarcopenia in normal aging.

Sarcopenia, which diminishes lifespan and healthspan in the elderly, is commonly exacerbated by viral pneumonia, including influenza and COVID-19. In a study of influenza A pneumonia in mice, young mice fully recovered from sarcopenia, while older mice did not. We identified a population of tissue-resident skeletal muscle macrophages that form a spatial niche with satellite cells and myofibers in young mice but are lost with age. Mice with a gain-of-function mutation in the Mertk receptor maintained this macrophage-myofiber interaction during aging and fully recovered from influenza-induced sarcopenia. In contrast, deletion of Mertk in macrophages or loss of Cx3cr1 disrupted this niche, preventing muscle regeneration. Heterochronic parabiosis did not restore the niche in old mice. These findings suggest that age-related loss of Mertk in muscle tissue-resident macrophages disrupts the cellular signaling necessary for muscle regeneration after viral pneumonia, offering a potential target to mitigate sarcopenia in aging.

immunology↗

bioRxiv2024

Metabolic tuning facilitates nociceptor resilience to excitotoxicity

The capsaicin receptor, TRPV1, mediates the detection of harmful chemical and thermal stimuli. Overactivation of TRPV1 can lead to cellular damage or death through excitotoxicity, a phenomenon associated with painful neuropathy and the paradoxical use of capsaicin as an analgesic. We exploited capsaicin-evoked death to conduct a systematic analysis of excitotoxicity through a genome-wide CRISPRi screen, thereby revealing a comprehensive network of regulatory pathways. We show that decreased expression of mitochondrial electron transport chain (ETC) components protects against capsaicin-induced toxicity by mitigating calcium imbalance and mitochondrial reactive oxygen species production via distinct pathways. Interestingly, TRPV1+ sensory neurons in adult mice maintain lower expression of ETC components and can better tolerate excitotoxicity and oxidative stress compared to other sensory neuron subtypes. We further confirm the regulatory roles of the ETC in sensory neurons through gain-of-function and loss-of-function experiments. These findings implicate ETC tuning as a cellular protective strategy against sensory excitotoxicity.

cell biology↗

bioRxiv2024

IFNγ-dependent metabolic reprogramming restrains an immature, pro-metastatic lymphatic state in melanoma

Lymphatic vessels play a crucial role in activating anti-tumor immune surveillance but also contribute to metastasis and systemic tumor progression. Whether distinct lymphatic phenotypes exist that govern the switch between immunity and metastasis remains unclear. Here we reveal that cytotoxic immunity normalizes lymphatic function and uncouples immune and metastatic potential. We find that in mice and humans, intratumoral lymphatic vessel density negatively correlates with productive cytotoxic immune responses and identify IFN{gamma} as an intrinsic inhibitor of lymphangiogenesis. Specific deletion of the Ifngr1 in lymphatic endothelial cells (LECs) greatly expanded the intratumoral lymphatic network and drove the emergence of a tip-like endothelial state, promoting lymph node metastasis but not dendritic cell migration. IFN{gamma} inhibits oxidative phosphorylation, which is required for proliferation and acquisition of the pathologic transcriptional state. Our data indicate that IFN{gamma} induces a phenotypic switch in tumor-associated lymphatic vessels to reinforce canonical immune surveillance and block metastasis.

cancer biology↗

bioRxiv2024

Immunomodulatory Role of the Stem Cell Circadian Clock in Muscle Repair

The circadian clock orchestrates vital physiological processes such as metabolism, immune function, and tissue regeneration, aligning them with the optimal time of day. This study identifies an intricate interplay between the circadian clock within muscle stem cells (SCs) and their capacity to modulate the immune microenvironment during muscle regeneration. We uncover that the SC clock provokes time of day-dependent induction of inflammatory response genes following injury, particularly those related to neutrophil activity and chemotaxis. These responses are driven by rhythms of cytosolic regeneration of the signaling metabolite NAD+. We demonstrate that genetically enhancing cytosolic NAD+ regeneration in SCs is sufficient to induce robust inflammatory responses that significantly influence muscle regeneration. Furthermore, using mononuclear single-cell sequencing of the regenerating muscle niche, we uncover a key role for the cytokine CCL2 in mediating SC-neutrophil crosstalk in a time of day-dependent manner. Our findings highlight a crucial intersection between SC metabolic shifts and immune responses within the muscle microenvironment, dictated by the circadian rhythms, and underscore the potential for targeting circadian and metabolic pathways to enhance tissue regeneration.

developmental biology↗

bioRxiv2024

Metabolic shift to serine pathway induced by lipids confers oncogenic properties in non-transformed breast cells

A lipid metabolism gene signature is associated with the risk of estrogen negative breast cancer (ER-BC). In vitro, lipid exposure alters histone methylation affecting gene expression and increasing flux through various metabolic reactions; but little is known about the mechanism(s) linking lipids and epigenetic reprogramming with the genesis of ER-BC. Here we show that the metabolism of the medium-chain fatty acid Octanoic Acid (OA) in preference to glucose and glutamine results in a metabolic shift toward the serine pathway increasing the production of SAM, glutathione, and 2-HG, with implications for oncogenesis: SAM production results in epigenetic fostered plasticity leading to reprogramming/selecting cells that express Neural, EMT and BC related genes. 2-HG exposure results in appearance of DNA breaks, potentially consequent to the inhibition of essential demethylases for HR repair. ROS increases shortly after OA exposure and is mitigated by antioxidant defenses, which favors/enables the survival of specific cell subtypes.

cancer biology↗

bioRxiv2023

Alpha-Synuclein pathology disrupts mitochondrial function in dopaminergic and cholinergic neurons at-risk in Parkinsons disease

BackgroundPathological accumulation of aggregated -synuclein (aSYN) is a common feature of Parkinsons disease (PD). However, the mechanisms by which intracellular aSYN pathology contributes to dysfunction and degeneration of neurons in the brain are still unclear. A potentially relevant target of aSYN is the mitochondrion. To test this hypothesis, genetic and physiological methods were used to monitor mitochondrial function in substantia nigra pars compacta (SNc) dopaminergic and pedunculopontine nucleus (PPN) cholinergic neurons after stereotaxic injection of aSYN pre-formed fibrils (PFFs) into the mouse brain. MethodsaSYN PPFs were stereotaxically injected into the SNc or PPN of mice. Twelve weeks later, mice were studied using a combination of approaches, including immunocytochemical analysis, cell- type specific transcriptomic profiling, electron microscopy, electrophysiology and two-photon-laser- scanning microscopy of genetically encoded sensors for bioenergetic and redox status. ResultsIn addition to inducing a significant neuronal loss, SNc injection of PFFs induced the formation of intracellular, phosphorylated aSYN aggregates selectively in dopaminergic neurons. In these neurons, PFF-exposure decreased mitochondrial gene expression, reduced the number of mitochondria, increased oxidant stress, and profoundly disrupted mitochondrial adenosine triphosphate production. Consistent with an aSYN-induced bioenergetic deficit, the autonomous spiking of dopaminergic neurons slowed or stopped. PFFs also up-regulated lysosomal gene expression and increased lysosomal abundance, leading to the formation of Lewy-like inclusions. Similar changes were observed in PPN cholinergic neurons following aSYN PFF exposure. ConclusionsTaken together, our findings suggest that disruption of mitochondrial function, and the subsequent bioenergetic deficit, is a proximal step in the cascade of events induced by aSYN pathology leading to dysfunction and degeneration of neurons at-risk in PD.

neuroscience↗