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
