N Nature Metabolism · Dec 05, 2025 Pathway coessentiality mapping reveals complex II is required for de novo purine biosynthesis in acute myeloid leukaemia Understanding how cellular pathways interact is crucial for treating complex diseases like cancer. Individual gene–gene interaction studies have provided valuable insights, but may miss pathways working together. Here we develop a multi-gene approach to pathway mapping which reveals that acute myeloid leukaemia (AML) depends on an unexpected link between complex II and purine metabolism. Through stable-isotope metabolomic tracing, we show that complex II directly supports de novo purine biosynthesis and that exogenous purines rescue AML cells from complex II inhibition. The mechanism involves a metabolic circuit where glutamine provides nitrogen to build the purine ring, producing glutamate that complex II metabolizes to sustain purine synthesis. This connection translates into a metabolic vulnerability whereby increasing intracellular glutamate levels suppresses purine production and sensitizes AML cells to complex II inhibition. In a syngeneic AML mouse model, targeting complex II leads to rapid disease regression and extends survival. In individuals with AML, higher complex II gene expression correlates with resistance to BCL-2 inhibition and worse survival. These findings establish complex II as a central regulator of de novo purine biosynthesis and a promising therapeutic target in AML. Acute myeloid leukaemia Cancer metabolism Metabolism Metabolomics biology mouse experiments
N Nature Metabolism · Dec 03, 2025 Age-related decline of chaperone-mediated autophagy in skeletal muscle leads to progressive myopathy Chaperone-mediated autophagy (CMA) contributes to proteostasis maintenance by selectively degrading a subset of proteins in lysosomes. CMA declines with age in most tissues, including skeletal muscle. However, the role of CMA in skeletal muscle and the consequences of its decline remain poorly understood. Here we demonstrate that CMA regulates skeletal muscle function. We show that CMA is upregulated in skeletal muscle in response to starvation, exercise and tissue repair, but declines in ageing and obesity. Using a muscle-specific CMA-deficient mouse model, we show that CMA loss leads to progressive myopathy, including reduced muscle force and degenerative myofibre features. Comparative proteomic analyses reveal CMA-dependent changes in the mitochondrial proteome and identify the sarcoplasmic–endoplasmic reticulum Ca2+-ATPase (SERCA) as a CMA substrate. Impaired SERCA turnover in CMA-deficient skeletal muscle is associated with defective calcium (Ca2+) storage and dysregulated Ca2+dynamics. We confirm that CMA is also downregulated with age in human skeletal muscle. Remarkably, genetic upregulation of CMA activity in old mice partially ameliorates skeletal muscle ageing phenotypes. Together, our work highlights the contribution of CMA to skeletal muscle homoeostasis and myofibre integrity. Ageing Chaperone-mediated autophagy Metabolism Skeletal muscle biology mouse experiments
N Nature Metabolism · Dec 03, 2025 Chaperone-mediated autophagy sustains muscle stem cell regenerative functions but declines with age Proteostasis supports stemness, and its loss correlates with the functional decline of diverse stem cell types. Chaperone-mediated autophagy (CMA) is a selective autophagy pathway implicated in proteostasis, but whether it plays a role in muscle stem cell (MuSC) function is unclear. Here we show that CMA is necessary for MuSC regenerative capacity throughout life. Genetic loss of CMA in young MuSCs, or failure of CMA in aged MuSCs, causes proliferative impairment resulting in defective skeletal muscle regeneration. Using comparative proteomics to identify CMA substrates, we find that actin cytoskeleton organization and glycolytic metabolism are key processes altered in aged murine and human MuSCs. CMA reactivation and glycolysis enhancement restore the proliferative capacity of aged mouse and human MuSCs, and improve their regenerative ability. Overall, our results show that CMA is a decisive stem cell-fate regulator, with implications in fostering muscle regeneration in old age. Chaperone-mediated autophagy Muscle stem cells biology mouse experiments
N Nature Metabolism · Dec 01, 2025 Fat sensory cues in early life program central response to food and obesity Maternal obesity predisposes offspring to metabolic diseases. Here, we show that non-nutritive sensory components of a high-fat diet (HFD), beyond its hypercaloric, obesogenic effects, are sufficient to alter metabolic health in the offspring. To dissociate the caloric and sensory components of HFD, we fed dams a bacon-flavoured diet, isonutritional to a normal chow diet but enriched with fat-related odours. Offspring exposed to these fat-related odours during development display metabolic inflexibility and increased adiposity when fed HFD in adulthood independently of maternal metabolic health. Developmental exposure to fat-related odours shifts mesolimbic dopaminergic circuits and Agouti-related peptide (AgRP) hunger neurons’ responses to phenocopy those of obese mice, including a desensitization of AgRP neurons to dietary fat. While neither neonatal optogenetic activation of sensory circuits nor passive exposure to fat-related odours is sufficient to alter metabolic responses to HFD, coupling optogenetic stimulation of sensory circuits with caloric intake exacerbates obesity. Collectively, we report that fat-related sensory cues during development act as signals that can prime central responses to food cues and whole-body metabolism regulation. Feeding behaviour Obesity biology mouse experiments
N Nature Metabolism · Nov 20, 2025 Hepatocyte mitochondrial NAD+content is limiting for liver regeneration Nicotinamide adenine dinucleotide (NAD+) precursor supplementation shows metabolic and functional benefits in rodent models of disease and is being explored as potential therapeutic strategy in humans. However, the wide range of processes that involve NAD+in every cell and subcellular compartment make it difficult to narrow down the mechanisms of action. Here we show that the rate of liver regeneration is closely associated with the concentration of NAD+in hepatocyte mitochondria. We find that the mitochondrial NAD+concentration in hepatocytes of male mice is determined by the expression of the transporter SLC25A51 (MCART1). The heterozygous loss of SLC25A51 modestly decreases mitochondrial NAD+content in multiple tissues and impairs liver regeneration, whereas the hepatocyte-specific overexpression of SLC25A51 is sufficient to enhance liver regeneration comparably to the effect of systemic NAD+precursor supplements. This benefit is observed even though NAD+levels are increased only in mitochondria. Thus, the hepatocyte mitochondrial NAD+pool is a key determinant of the rate of liver regeneration. Energy metabolism Homeostasis Metabolomics biology mouse experiments
N Nature Metabolism · Nov 14, 2025 Glycerol-3-phosphate activates ChREBP, FGF21 transcription and lipogenesis in citrin deficiency Citrin deficiency (CD) is caused by the inactivation of SLC25A13, a mitochondrial membrane protein required to move electrons from cytosolic NADH to the mitochondrial matrix in hepatocytes. People with CD do not like sweets. Here we show that SLC25A13 loss causes the accumulation of glycerol-3-phosphate (G3P), which activates the carbohydrate response element-binding protein (ChREBP) to transcribe FGF21, which acts in the brain to restrain intake of sweets and alcohol and to transcribe key genes driving lipogenesis. Mouse and human data suggest that G3P–ChREBP is a mechanistic component of the Randle Cycle that contributes to metabolic-dysfunction-associated steatotic liver disease and forms part of a system that communicates metabolic states from the liver to the brain in a manner that alters food and alcohol choices. The data provide a framework for understanding FGF21 induction in varied conditions, suggest ways to develop FGF21-inducing drugs and suggest potential drug candidates for lean metabolic-dysfunction-associated steatotic liver disease and support of urea cycle function in CD. Gene regulation Liver Metabolic diseases Metabolism Transcriptional regulatory elements biology mouse experiments
N Nature Metabolism · Nov 13, 2025 Uridine-sensitized screening identifies demethoxy-coenzyme Q and NUDT5 as regulators of nucleotide synthesis Rapidly proliferating cells require large amounts of nucleotides, making nucleotide metabolism a widely exploited therapeutic target against cancer, autoinflammatory disorders and viral infections. However, regulation of nucleotide metabolism remains incompletely understood. Here, we reveal regulators of de novo pyrimidine synthesis. Using uridine-sensitized CRISPR-Cas9 screening, we show that coenzyme Q (CoQ) is dispensable for pyrimidine synthesis, in the presence of the demethoxy-CoQ intermediate as alternative electron acceptor. We further report that the ADP-ribose pyrophosphatase NUDT5 directly binds PPAT, the rate-limiting enzyme in purine synthesis, which inhibits its activity and preserves the phosphoribosyl pyrophosphate (PRPP) pool. In the absence of NUDT5, hyperactive purine synthesis exhausts the PRPP pool at the expense of pyrimidine synthesis, which promotes resistance to purine and pyrimidine nucleobase analogues. Of note, the interaction between NUDT5 and PPAT is disrupted by PRPP, highlighting an intricate allosteric regulation. Overall, our findings reveal a fundamental mechanism of nucleotide balance and position NUDT5 as a regulator of nucleobase analogue metabolism. Metabolism Metabolomics Multienzyme complexes Nucleic acids biology
N Nature Metabolism · Nov 12, 2025 Impaired cAMP–PKA–CREB1 signalling drives mitochondrial dysfunction in skeletal muscle during cancer cachexia Skeletal muscle wasting is a defining feature of cancer cachexia, a multifactorial syndrome that drastically compromises patient quality of life and treatment outcomes. Mitochondrial dysfunction is a major contributor to skeletal muscle wasting in cancer cachexia, yet the upstream molecular drivers remain elusive. Here we show that cancer impairs the activity of cAMP-dependent protein kinase A (PKA) and of its transcriptional effector CREB1 in skeletal muscle, ultimately contributing to the downregulation of a core transcriptional network that supports mitochondrial integrity and function. The restoration of cAMP–PKA–CREB1 signalling through pharmacological inhibition of the cAMP-hydrolysing phosphodiesterase 4 (PDE4) rescues the expression of mitochondrial-related genes, improves mitochondrial function and mitigates skeletal muscle wasting in male mice. Altogether, our data identify tumour-induced suppression of the cAMP–PKA–CREB1 axis as a central mechanism contributing to mitochondrial dysfunction in skeletal muscle during cancer cachexia. Furthermore, these findings highlight PDE4, particularly the PDE4D isoform, as a potential therapeutic target to preserve muscle mitochondrial function and counteract muscle wasting in cancer cachexia. Cancer Cell signalling Metabolism Mitochondria Skeletal muscle biology mouse experiments
N Nature Metabolism · Nov 10, 2025 Identification of a common ketohexokinase-dependent link driving alcohol intake and alcohol-associated liver disease in mice Alcohol and sugar share reinforcing properties and both contribute to liver disease progression, ultimately leading to cirrhosis. Emerging evidence suggests that ethanol activates the aldose reductase pathway, resulting in endogenous fructose production. Here we investigated whether alcohol preference and alcohol-associated liver disease (ALD) are mediated through fructose metabolism by ketohexokinase (KHK)-A/C. Using global, conditional and tissue-specific KHK-A/C knockout mice, we assessed ethanol intake, reinforcement behaviours and liver injury. Ethanol consumption increased portal vein osmolality and activated the polyol pathway in the liver and intestine, leading to fructose production metabolized by KHK-A/C. Mice lacking KHK-A/C showed reduced ethanol preference across multiple paradigms, including two-bottle choice, conditioned place preference and operant self-administration, alongside decreased ∆FosB expression in the nucleus accumbens. Both genetic deletion and pharmacologic inhibition of KHK-A/C suppressed ethanol intake. Hepatocyte-specific KHK-A/C knockout mice displayed partially reduced alcohol consumption, potentially linked to altered aldehyde dehydrogenase expression, while intestinal KHK-A/C deletion restored glucagon-like peptide-1 levels—a hormone known to suppress alcohol intake. Under ethanol pair-matched conditions, global and liver-specific KHK-A/C knockout mice were protected from ALD, with marked reductions in hepatic steatosis, inflammation and fibrosis. These findings identify ethanol-induced fructose metabolism as a key driver of excessive alcohol consumption and ALD pathogenesis. Given that ALD and metabolic dysfunction-associated steatotic liver disease share fructose-dependent mechanisms, targeting fructose metabolism may offer a novel therapeutic approach for treating alcohol use disorder and related liver injury. Metabolic diseases Metabolic disorders Metabolism biology mouse experiments
N Nature Metabolism · Nov 06, 2025 Blood methylome signatures in children exposed to maternal type 1 diabetes are linked to protection against islet autoimmunity Exposure to maternal type 1 diabetes (T1D) during pregnancy provides relative protection against T1D in the offspring. This protective effect may be driven by epigenetic mechanisms. Here we conducted an epigenome-wide blood analysis on 790 young children with and 962 children without a T1D-affected mother, and identified differential DNA methylation (q< 0.05) at multiple loci and regions. These included the Homeobox A gene cluster and 15 T1D susceptibility genes. The differential methylation was found in transcriptionally relevant regions associated with immune function, including sites previously linked to T1D-related methylation loci and protein biomarkers. Propensity scores for methylation at T1D susceptibility loci could predict the development of islet autoimmunity in offspring born to mothers without T1D. Together, these findings highlight pathways through which maternal T1D may confer protection against islet autoimmunity in offspring and suggest that environmental factors can influence T1D risk through epigenetic modifications of T1D susceptibility loci. Epigenomics Metabolism Type 1 diabetes biology
