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Timed feeding drives adipose browning, although the integrative mechanisms for the same remain unclear. Here, we show that twice-a-night (TAN) feeding generates biphasic oscillations of circulating insulin and leptin, representing their entrainment by timed feeding. Insulin and leptin surges lead to marked cellular, functional, and metabolic remodeling of subcutaneous white adipose tissue (sWAT), resulting in increased energy expenditure. Single-cell RNA-sequencing (scRNA-seq) analyses and flow cytometry demonstrate a role for insulin and leptin surges in innate lymphoid type 2 (ILC2) cell recruitment and sWAT browning, since sWAT depot denervation or loss of leptin or insulin receptor signaling or ILC2 recruitment each dampens TAN feeding-induced sWAT remodeling and energy expenditure. Consistently, recreating insulin and leptin oscillations via once-a-day timed co-injections is sufficient to favorably remodel innervated sWAT. Innervation is necessary for sWAT remodeling, since denervation of sWAT, but not brown adipose tissue (BAT), blocks TAN-induced sWAT remodeling and resolution of inflammation. In sum, reorganization of nutrient-sensitive pathways remodels sWAT and drives the metabolic benefits of timed feeding.

Insulin-mechanistic target of rapamycin (mTOR) signaling drives anabolic growth during organismal development; its late-life dysregulation contributes to aging and limits lifespans. Age-related regulatory mechanisms and functional consequences of insulin-mTOR remain incompletely understood. Here, we identify LPD-3 as a megaprotein that orchestrates the tempo of insulin-mTOR signaling during C. elegans aging. We find that an agonist insulin, INS-7, is drastically overproduced from early life and shortens lifespan in lpd-3 mutants. LPD-3 forms a bridge-like tunnel megaprotein to facilitate non-vesicular cellular lipid trafficking. Lipidomic profiling reveals increased hexaceramide species in lpd-3 mutants, accompanied by up-regulation of hexaceramide biosynthetic enzymes, including HYL-1. Reducing the abundance of HYL-1, insulin receptor/DAF-2 or mTOR/LET-363, normalizes INS-7 levels and rescues the lifespan of lpd-3 mutants. LPD-3 antagonizes SINH-1, a key mTORC2 component, and decreases expression with age. We propose that LPD-3 acts as a megaprotein brake for organismal aging and that its age-dependent decline restricts lifespan through the sphingolipid-hexaceramide and insulin-mTOR pathways.

Opioids are generally known to promote hedonic food consumption. Although much of the existing evidence is primarily based on studies of the mesolimbic pathway, endogenous opioids and their receptors are widely expressed in hypothalamic appetite circuits as well; however, their role in homeostatic feeding remains unclear. Using a fluorescent opioid sensor, deltaLight, here we report that mediobasal hypothalamic opioid levels increase by feeding, which directly and indirectly inhibits agouti-related protein (AgRP)-expressing neurons through the μ-opioid receptor (MOR). AgRP-specific MOR expression increases by energy surfeit and contributes to opioid-induced suppression of appetite. Conversely, its antagonists diminish suppression of AgRP neuron activity by food and satiety hormones. Mice with AgRP neuron-specific ablation of MOR expression have increased fat preference without increased motivation. These results suggest that post-ingestion release of endogenous opioids contributes to AgRP neuron inhibition to shape food choice through MOR signaling.

Mitochondria use the electron transport chain to generate high-energy phosphate from oxidative phosphorylation, a process also regulated by the mitochondrial Ca2+ uniporter (MCU) and Ca2+ levels. Here, we show that MCUb, an inhibitor of MCU-mediated Ca2+ influx, is induced by caloric restriction, where it increases mitochondrial fatty acid utilization. To mimic the fasted state with reduced mitochondrial Ca2+ influx, we generated genetically altered mice with skeletal muscle-specific MCUb expression that showed greater fatty acid usage, less fat accumulation, and lower body weight. In contrast, mice lacking Mcub in skeletal muscle showed increased pyruvate dehydrogenase activity, increased muscle malonyl coenzyme A (CoA), reduced fatty acid utilization, glucose intolerance, and increased adiposity. Mechanistically, pyruvate dehydrogenase kinase 4 (PDK4) overexpression in muscle of Mcub-deleted mice abolished altered substrate preference. Thus, MCUb is an inducible control point in regulating skeletal muscle mitochondrial Ca2+ levels and substrate utilization that impacts total metabolic balance.

Maintaining healthy adipose tissue is crucial for metabolic health, requiring a deeper understanding of adipocyte development and response to high-calorie diets. This study highlights the importance of TET3 during white adipose tissue (WAT) development and expansion. Selective depletion of Tet3 in adipose precursor cells (APCs) reduces adipogenesis, protects against diet-induced adipose expansion, and enhances whole-body metabolism. Transcriptomic analysis of wild-type and Tet3 knockout (KO) APCs unveiled TET3 target genes, including Pparg and several genes linked to the extracellular matrix, pivotal for adipogenesis and remodeling. DNA methylation profiling and functional studies underscore the importance of DNA demethylation in gene regulation. Remarkably, targeted DNA demethylation at the Pparg promoter restored its transcription. In conclusion, TET3 significantly governs adipogenesis and diet-induced adipose expansion by regulating key target genes in APCs.

The mechanical properties of solid tumors influence tumor cell phenotype and the ability to invade surrounding tissues. Using bioengineered scaffolds to provide a matrix microenvironment for patient-derived glioblastoma (GBM) spheroids, this study demonstrates that a soft, brain-like matrix induces GBM cells to shift to a glycolysis-weighted metabolic state, which supports invasive behavior. We first show that orthotopic murine GBM tumors are stiffer than peritumoral brain tissues, but tumor stiffness is heterogeneous where tumor edges are softer than the tumor core. We then developed 3D scaffolds with μ-compressive moduli resembling either stiffer tumor core or softer peritumoral brain tissue. We demonstrate that the softer matrix microenvironment induces a shift in GBM cell metabolism toward glycolysis, which manifests in lower proliferation rate and increased migration activities. Finally, we show that these mechanical cues are transduced from the matrix via CD44 and integrin receptors to induce metabolic and phenotypic changes in cancer cells.

Cold-induced brown adipose tissue (BAT) activation is considered to improve metabolic health. In murine BAT, cold increases the fundamental molecule for mitochondrial function, nicotinamide adenine dinucleotide (NAD+), but limited knowledge of NAD+ metabolism during cold in human BAT metabolism exists. We show that cold increases the serum metabolites of the NAD+ salvage pathway (nicotinamide and 1-methylnicotinamide) in humans. Additionally, individuals with cold-stimulated BAT activation have decreased levels of metabolites from the de novo NAD+ biosynthesis pathway (tryptophan, kynurenine). Serum nicotinamide correlates positively with cold-stimulated BAT activation, whereas tryptophan and kynurenine correlate negatively. Furthermore, the expression of genes involved in NAD+ biosynthesis in BAT is related to markers of metabolic health. Our data indicate that cold increases serum tryptophan conversion to nicotinamide to be further utilized by BAT. We conclude that NAD+ metabolism is activated upon cold in humans and is probably regulated in a coordinated fashion by several tissues.

Cholesterol is a structural component of cell membranes. How rapidly growing tumor cells maintain membrane cholesterol homeostasis is poorly understood. Here, we found that glioblastoma (GBM), the most lethal brain tumor, maintains normal levels of membrane cholesterol but with an abundant presence of cholesteryl esters (CEs) in its lipid droplets (LDs). Mechanistically, SREBP-1 (sterol regulatory element-binding protein 1), a master transcription factor that is activated upon cholesterol depletion, upregulates critical autophagic genes, including ATG9B, ATG4A, and LC3B, as well as lysosome cholesterol transporter NPC2. This upregulation promotes LD lipophagy, resulting in the hydrolysis of CEs and the liberation of cholesterol from the lysosomes, thus maintaining plasma membrane cholesterol homeostasis. When this pathway is blocked, GBM cells become quite sensitive to cholesterol deficiency with poor growth in vitro. Our study unravels an SREBP-1-autophagy-LD-CE hydrolysis pathway that plays an important role in maintaining membrane cholesterol homeostasis while providing a potential therapeutic avenue for GBM.

Branched-chain amino acid (BCAA) metabolism is linked to glucose homeostasis, but the underlying signaling mechanisms are unclear. We find that gluconeogenesis is reduced in mice deficient of Ppm1k, a positive regulator of BCAA catabolism, which protects against obesity-induced glucose intolerance. Accumulation of branched-chain keto acids (BCKAs) inhibits glucose production in hepatocytes. BCKAs suppress liver mitochondrial pyruvate carrier (MPC) activity and pyruvate-supported respiration. Pyruvate-supported gluconeogenesis is selectively suppressed in Ppm1k-deficient mice and can be restored with pharmacological activation of BCKA catabolism by BT2. Finally, hepatocytes lack branched-chain aminotransferase that alleviates BCKA accumulation via reversible conversion between BCAAs and BCKAs. This renders liver MPC most susceptible to circulating BCKA levels hence a sensor of BCAA catabolism.

Pre-metastatic niche formation is a critical step during the metastatic spread of cancer. One way by which primary tumors prime host cells at future metastatic sites is through the shedding of tumor-derived microparticles as a consequence of vascular sheer flow. However, it remains unclear how the uptake of such particles by resident immune cells affects their phenotype and function. Here, we show that ingestion of tumor-derived microparticles by macrophages induces a rapid metabolic and phenotypic switch that is characterized by enhanced mitochondrial mass and function, increased oxidative phosphorylation, and upregulation of adhesion molecules, resulting in reduced motility in the early metastatic lung. This reprogramming event is dependent on signaling through the mTORC1, but not the mTORC2, pathway and is induced by uptake of tumor-derived microparticles. Together, these data support a mechanism by which uptake of tumor-derived microparticles induces reprogramming of macrophages to shape their fate and function in the early metastatic lung.

Physiology is regulated by interconnected cell and tissue circadian clocks. Disruption of the rhythms generated by the concerted activity of these clocks is associated with metabolic disease. Here we tested the interactions between clocks in two critical components of organismal metabolism, liver and skeletal muscle, by rescuing clock function either in each organ separately or in both organs simultaneously in otherwise clock-less mice. Experiments showed that individual clocks are partially sufficient for tissue glucose metabolism, yet the connections between both tissue clocks coupled to daily feeding rhythms support systemic glucose tolerance. This synergy relies in part on local transcriptional control of the glucose machinery, feeding-responsive signals such as insulin, and metabolic cycles that connect the muscle and liver. We posit that spatiotemporal mechanisms of muscle and liver play an essential role in the maintenance of systemic glucose homeostasis and that disrupting this diurnal coordination can contribute to metabolic disease.

Summary: Metabolites that mark aging are not fully known. We analyze 408 plasma metabolites in Long Life Family Study participants to characterize markers of age, aging, extreme longevity, and mortality. We identify 308 metabolites associated with age, 258 metabolites that change over time, 230 metabolites associated with extreme longevity, and 152 metabolites associated with mortality risk. We replicate many associations in independent studies. By summarizing the results into 19 signatures, we differentiate between metabolites that may mark aging-associated compensatory mechanisms from metabolites that mark cumulative damage of aging and from metabolites that characterize extreme longevity. We generate and validate a metabolomic clock that predicts biological age. Network analysis of the age-associated metabolites reveals a critical role of essential fatty acids to connect lipids with other metabolic processes. These results characterize many metabolites involved in aging and point to nutrition as a source of intervention for healthy aging therapeutics.

Summary: Cytochrome b5 (CYB5) is a hemoprotein crucial for electron transfer to oxygenases. Although microsomal CYB5A is required for sterol C4-demethylation in vitro, cholesterol biosynthesis remains intact in Cyb5a knockout mice. Here, we show that knockout of mitochondrial CYB5B, rather than CYB5A, blocks cholesterol biosynthesis at the sterol-C4 oxidation step in HeLa cells, causing an accumulation of testis meiosis-activating sterol (T-MAS) and dihydro-T-MAS. Surprisingly, liver-specific Cyb5b knockout (L-Cyb5b−/−) mice exhibit normal cholesterol metabolism. Further knockdown of Cyb5a in L-Cyb5b−/− (L-Cyb5b−/−/short hairpin [sh]Cyb5a) mice leads to a marked accumulation of T-MAS and dihydro-T-MAS, indicating that either CYB5A or CYB5B is required for sterol C4-demethylation. The L-Cyb5b−/−/shCyb5a mice are largely normal, with lower sterol regulatory element-binding protein (SREBP)-target gene expression during refeeding and higher liver triglyceride levels while fasting, as T-MAS and dihydro-T-MAS inhibit the SREBP pathway and activate the PPARγ pathway. In summary, CYB5A and CYB5B compensate for sterol C4-demethylation, and T-MAS and dihydro-T-MAS can modulate the SREBP and PPARγ pathways.

Summary: Calcium ions play important roles in nearly every biological process, yet whole-proteome analysis of calcium effectors has been hindered by a lack of high-throughput, unbiased, and quantitative methods to identify protein-calcium engagement. To address this, we adapted protein thermostability assays in budding yeast, human cells, and mouse mitochondria. Based on calcium-dependent thermostability, we identified 2,884 putative calcium-regulated proteins across human, mouse, and yeast proteomes. These data revealed calcium engagement of signaling hubs and cellular processes, including metabolic enzymes and the spliceosome. Cross-species comparison of calcium-protein engagement and mutagenesis experiments identified residue-specific cation engagement, even within well-known EF-hand domains. Additionally, we found that the dienoyl-coenzyme A (CoA) reductase DECR1 binds calcium at physiologically relevant concentrations with substrate-specific affinity, suggesting direct calcium regulation of mitochondrial fatty acid oxidation. These discovery-based proteomic analyses of calcium effectors establish a key resource to dissect cation engagement and its mechanistic effects across multiple species and diverse biological processes.

Summary: The transcription repressor Bach2 plays a crucial role in shaping humoral immunity, but its cell-autonomous function remains elusive. Here, we reveal the mechanism by which Bach2 regulates effector cell maturation in peripheral B cells. In response to Toll-like receptor (TLR) agonists, Bach2 deficiency promotes the differentiation of follicular, but not marginal zone, B cells into effector cells, producing interleukin (IL)-6 and antibodies. This phenomenon is associated with changes in lipid metabolism, such as increases in CD36 expression, lipid influx, and fatty acid oxidation. Consistent with this, Bach2-deficient B cells exhibit elevated levels of mitochondrial oxidative stress, lipid peroxidation, and p38 activation. Mechanistically, Bach2 acts as a repressor of Cd36, and inhibition of CD36 or fatty acid oxidation reduces the differentiation of naive B cells into IL-6- and antibody-secreting cells. These results indicate Bach2 as a key metabolic checkpoint regulator crucial for maintaining a functionally quiescent state of follicular B cells.

Summary: Organisms integrate circadian and metabolic signals to optimize substrate selection to survive starvation, yet precisely how this occurs is unclear. Here, we show that hepatocyte Period 1 (Per1) is selectively induced during fasting, and mice lacking hepatocyte Per1 fail to initiate autophagic flux, ketogenesis, and lipid accumulation. Transcriptomic analyses show failed induction of the fasting hepatokine Fgf21 in Per1-deficient mice, and single-nucleus multiome sequencing defines a putative responding hepatocyte subpopulation that fails to induce the chromatin accessibility near the Fgf21 locus. In vivo isotopic tracing and indirect calorimetry demonstrate that hepatocyte Per1-deficient mice fail to transit from oxidation of glucose to fat, which is completely reversible by exogenous FGF21 or by inhibiting pyruvate dehydrogenase. Strikingly, disturbing other core circadian genes does not perturb Per1 induction during fasting. We thus describe Per1 as an important mechanism by which hepatocytes integrate internal circadian rhythm and external nutrition signals to facilitate proper fuel utilization.

Summary: Inhibition of the ceramide synthetic pathway with myriocin or an antisense oligonucleotide (ASO) targeting dihydroceramide desaturase (DES1) both improved hepatic insulin sensitivity in rats fed either a saturated or unsaturated fat diet and was associated with reductions in both hepatic ceramide and plasma membrane (PM)-sn-1,2-diacylglycerol (DAG) content. The insulin sensitizing effects of myriocin and Des1 ASO were abrogated by acute treatment with an ASO against DGAT2, which increased hepatic PM-sn-1,2-DAG but not hepatic C16 ceramide content. Increased PM-sn-1,2-DAG content was associated with protein kinase C (PKC)ε activation, increased insulin receptor (INSR)T1150 phosphorylation leading to reduced insulin-stimulated INSRY1152/AktS473 phosphorylation, and impaired insulin-mediated suppression of endogenous glucose production. These results demonstrate that inhibition of de novo ceramide synthesis by either myriocin treatment or DES1 knockdown protects against lipid-induced hepatic insulin resistance through a C16 ceramide-independent mechanism and that they mediate their effects to protect from lipid-induced hepatic insulin resistance via the PM-sn-1,2-DAG-PKCε-INSRT1150 phosphorylation pathway.

Summary: Targeting the distinct metabolic needs of tumor cells has recently emerged as a promising strategy for cancer therapy. The heterogeneous, context-dependent nature of cancer cell metabolism, however, poses challenges to identifying effective therapeutic interventions. Here, we utilize various unsupervised and supervised multivariate modeling approaches to systematically pinpoint recurrent metabolic states within hundreds of cancer cell lines, elucidate their association with tumor lineage and growth environments, and uncover vulnerabilities linked to their metabolic states across diverse genetic and tissue contexts. We validate key findings via analysis of data from patient-derived tumors and pharmacological screens and by performing genetic and pharmacological experiments. Our analysis uncovers synthetically lethal associations between the tumor metabolic state (e.g., oxidative phosphorylation), driver mutations (e.g., loss of tumor suppressor PTEN), and actionable biological targets (e.g., mitochondrial electron transport chain). Investigating the mechanisms underlying these relationships can inform the development of more precise and context-specific, metabolism-targeted cancer therapies.

Summary: Compartment-specific cellular membrane protein turnover is not well understood. We show that FBXO10, the interchangeable component of the cullin-RING-ligase 1 complex, undergoes lipid modification with geranylgeranyl isoprenoid at cysteine953, facilitating its dynamic trafficking to the outer mitochondrial membrane (OMM). FBXO10 polypeptide lacks a canonical mitochondrial targeting sequence (MTS); instead, its geranylgeranylation at C953 and interaction with two cytosolic factors, cytosolic factor-like δ subunit of type 6 phosphodiesterase (PDE6δ; a prenyl-group-binding protein) and heat shock protein 90 (HSP90; a chaperone), orchestrate specific OMM targeting of prenyl-FBXO10. The FBXO10(C953S) mutant redistributes away from the OMM, impairs mitochondrial ATP production and membrane potential, and increases fragmentation. Phosphoglycerate mutase-5 (PGAM5) was identified as a potential substrate of FBXO10 at the OMM using comparative quantitative proteomics of enriched mitochondria. FBXO10 loss or expression of prenylation-deficient FBXO10(C953S) inhibited PGAM5 degradation, disrupted mitochondrial homeostasis, and impaired myogenic differentiation of human induced pluripotent stem cells (iPSCs) and murine myoblasts. Our studies identify a mechanism for FBXO10-mediated regulation of selective mitochondrial proteostasis potentially amenable to therapeutic intervention.

Summary: How do neural circuits coordinate multiple behavioral responses to a single sensory cue? Here, we investigate how sweet taste drives appetitive behaviors in Drosophila, including feeding, locomotor suppression, spatial preference, and associative learning. We find that neural circuits mediating different innate responses to sugar are partially overlapping and diverge at the second and third layers. Connectomic analyses reveal distinct subcircuits that mediate different behaviors. Connectome-based simulations of neuronal activity predict that second-order sugar neurons act synergistically to promote downstream activity and that bitter input overrides the sugar circuit through multiple pathways acting at third- and fourth-order neurons. Consistent with the latter prediction, optogenetic experiments suggest that bitter input inhibits third- and fourth-order sugar neurons to override the sugar pathway, whereas hunger and diet act earlier in the circuit to modulate behavior. Together, these studies provide insight into how circuits are organized to drive diverse behavioral responses to a single stimulus.

Summary: The catalytic activity of most epigenetic enzymes requires a metabolite produced by central carbon metabolism as a cofactor or (co-)substrate. The concentrations of these metabolites undergo dynamic changes in response to nutrient levels and environmental conditions, reprogramming metabolic processes and epigenetic landscapes. Abnormal accumulations of epigenetic modulatory metabolites resulting from mutations in metabolic enzymes contribute to tumorigenesis. In this review, we first present the concept that metabolite regulation of gene expression represents an evolutionarily conserved mechanism from prokaryotes to eukaryotes. We then review how individual metabolites affect epigenetic enzymes and cancer development. Lastly, we discuss the advancement of and opportunity for therapeutic targeting of metabolite-epigenetic regulation in cancer therapy.

Summary: Lifespan is influenced by complex interactions between genetic and environmental factors. Studying those factors in model organisms of a single genetic background limits their translational value for humans. Here, we mapped lifespan determinants in 85 C. elegans recombinant inbred advanced intercross lines (RIAILs). We assessed molecular profiles—transcriptome, proteome, and lipidome—and life-history traits, including lifespan, development, growth dynamics, and reproduction. RIAILs exhibited large variations in lifespan, which correlated positively with developmental time. We validated three longevity modulators, including rict-1, gfm-1, and mltn-1, among the top candidates obtained from multiomics data integration and quantitative trait locus (QTL) mapping. We translated their relevance to humans using UK Biobank data and showed that variants in GFM1 are associated with an elevated risk of age-related heart failure. We organized our dataset as a resource that allows interactive explorations for new longevity targets.

Summary: Under stress, protein synthesis is attenuated to preserve energy and mitigate challenges to protein homeostasis. Here, we describe, with high temporal resolution, the dynamic landscape of changes in the abundance of proteins synthesized upon stress from transient mitochondrial inner membrane depolarization. This nascent proteome was altered when global translation was attenuated by stress and began to normalize as translation was recovering. This transition was associated with a transient desynchronization of cytosolic and mitochondrial translation and recovery of cytosolic and mitochondrial ribosomal proteins. Further, the elongation factor EEF1A1 was downregulated upon mitochondrial stress, and its silencing mimicked the stress-induced nascent proteome remodeling, including alterations in the nascent respiratory chain proteins. Unexpectedly, the stress-induced alterations in the nascent proteome were independent of physiological protein abundance and turnover. In summary, we provide insights into the physiological and pathological consequences of mitochondrial function and dysfunction.

Summary: Cell division is tightly regulated and requires an expanded energy supply. However, how this energy is generated remains unclear. Here, we establish a correlation between two mitochondrial Ca2+ influx events and ATP production during mitosis. While both events promote ATP production during mitosis, the second event, the Ca2+ influx surge, is substantial. To facilitate this Ca2+ influx surge, the lamin B receptor (LBR) organizes a mitosis-specific endoplasmic reticulum (ER)-mitochondrial contact site (ERMCS), creating a rapid Ca2+ transport pathway. LBR acts as a tether, connecting the ER Ca2+ release channel IP3R with the mitochondrial VDAC2. Depletion of LBR disrupts the Ca2+ influx surge, reduces ATP production, and postpones the metaphase-anaphase transition and subsequent cell division. These findings provide insight into the mechanisms underlying mitotic energy production and supply required for cell proliferation.

Summary: The gut microbiota influences physiological functions of the host, ranging from the maintenance of local gut homeostasis to systemic immunity and metabolism. Secreted phospholipase A2 group X (sPLA2-X) is abundantly expressed in colonic epithelial cells but is barely detectable in metabolic and immune tissues. Despite this distribution, sPLA2-X-deficient (Pla2g10−/−) mice displayed variable obesity-related phenotypes that were abrogated after treatment with antibiotics or cohousing with Pla2g10+/+ mice, suggesting the involvement of the gut microbiota. Under housing conditions where Pla2g10−/− mice showed aggravation of diet-induced obesity and insulin resistance, they displayed increased colonic inflammation and epithelial damage, reduced production of polyunsaturated fatty acids (PUFAs) and lysophospholipids, decreased abundance of several Clostridium species, and reduced levels of short-chain fatty acids (SCFAs). These obesity-related phenotypes in Pla2g10−/− mice were reversed by dietary supplementation with ω3 PUFAs or SCFAs. Thus, colonic sPLA2-X orchestrates ω3 PUFA-SCFA interplay via modulation of the gut microbiota, thereby secondarily affecting systemic metabolism.

Summary: Phenotypic associations have been reported between heart failure (HF) and blood lipids (BLs), blood pressure (BP), and blood glucose (BG). However, the shared genetic etiology underlying these associations remains incompletely understood. Conducting a large-scale multi-trait association study for HF with these traits, we discovered 143 previously unreported genomic risk loci for HF. Results showed that 46, 35, and 14 colocalized loci were shared by HF with BLs, BP, and BG, respectively. Notably, the loci shared by HF with these traits rarely overlapped, indicating distinct mechanisms. The combination of gene-mapping, gene-based, and transcriptome-wide association analyses prioritized noteworthy candidate genes (such as lipoprotein lipase [LPL], G protein-coupled receptor kinase 5 [GRK5], and troponin C1, slow skeletal and cardiac type [TNNC1]) for HF. Enrichment analysis revealed that HF exhibited comparable characteristics to cardiovascular traits and metabolic traits correlated to BLs, BP, and BG. Finally, we reported drug repurposing candidates and plasma protein targets for HF. These results provide biological insights into the pathogenesis of these comorbidities of HF.

Summary: Macrophages exhibit diverse phenotypes and respond flexibly to environmental cues through metabolic remodeling. In this study, we present a comprehensive multi-omics dataset integrating intra- and extracellular metabolomes with transcriptomic data to investigate the metabolic impact on human macrophage function. Our analysis establishes a metabolite-gene correlation network that characterizes macrophage activation. We find that the concurrent inhibition of tryptophan catabolism by IDO1 and IL4I1 inhibitors suppresses the macrophage pro-inflammatory response, whereas single inhibition leads to pro-inflammatory activation. We find that a subset of anti-inflammatory macrophages activated by Fc receptor signaling promotes glycolysis, challenging the conventional concept of reduced glycolysis preference in anti-inflammatory macrophages. We demonstrate that cholesterol accumulation suppresses macrophage IFN-γ responses. Our integrated network enables the discovery of immunometabolic features, provides insights into macrophage functional metabolic reprogramming, and offers valuable resources for researchers exploring macrophage immunometabolic characteristics and potential therapeutic targets for immune-related disorders.

Summary: Pyroptosis, a pro-inflammatory form of programmed cell death, is crucial for host defense against pathogens and danger signals. Proteolytic cleavage of gasdermin proteins B–E (GSDMB–GSDME) is well established as a trigger for pyroptosis, but the intracellular activation mechanism of GSDMA remains elusive. Here, we demonstrate that severe starvation induces pyroptosis through phosphorylation-induced activation of GSDMA. Nutrient stresses stimulate GSDMA activation via phosphorylation mediated by Unc-51-like autophagy-activating kinase 1 (ULK1). Phosphorylation of Ser353 on human GSDMA by ULK1 or the phospho-mimetic Ser353Asp mutant of GSDMA liberates GSDMA from auto-inhibition, facilitating its membrane targeting and initiation of pyroptosis. To further validate the significance of GSDMA phosphorylation, we generated a constitutively active mutant Ser354Asp of mouse Gsdma, which induced skin inflammation and hyperplasia in mice, reminiscent of phenotypes with activated Gsdma. This study uncovers phosphorylation of GSDMA as a mechanism underlying pyroptosis initiation and cellular response to nutrient stress.

Summary: Nutrient digestion, absorption, and export must be coordinated in the gut to meet the nutritional needs of the organism. We used the Drosophila intestine to characterize the mechanisms that coordinate the fate of dietary lipids. We identified enterocytes specialized in absorbing and exporting lipids to peripheral organs. Distinct hepatocyte-like cells, called oenocytes, communicate with these enterocytes to adjust intestinal lipid storage and export. A single transcription factor, Drosophila hepatocyte nuclear factor 4 (dHNF4), supports this gut-liver axis. In enterocytes, dHNF4 maximizes dietary lipid export by preventing their sequestration in cytoplasmic lipid droplets. In oenocytes, dHNF4 promotes the expression of the insulin antagonist ImpL2 to activate Foxo and suppress lipid retention in enterocytes. Disruption of this switch between lipid storage and export is associated with intestinal inflammation, suggesting a lipidic origin for inflammatory bowel diseases. These studies establish dHNF4 as a central regulator of intestinal metabolism and inter-organ lipid trafficking.

Summary: The strategy of lowering cholesterol levels by promoting cholesterol excretion is still lacking, and few molecular targets act on multiple cholesterol metabolic processes. In this study, we find that Nogo-B deficiency/inhibition simultaneously promotes hepatic uptake of cholesterol and cholesterol excretion. Nogo-B deficiency decreases cholesterol levels by activating ATP-binding cassette transporters (ABCs), apolipoprotein E (ApoE), and low-density lipoprotein receptor (LDLR) expression. We discover that Nogo-B interacts with liver X receptor α (LXRα), and Nogo-B deficiency inhibits ubiquitination degradation of LXRα, thereby enhancing its function on cholesterol excretion. Decreased cellular cholesterol levels further activate SREBP2 and LDLR expression, thereby promoting hepatic uptake of cholesterol. Nogo-B inhibition decreases atherosclerotic plaques and cholesterol levels in mice, and Nogo-B levels are correlated to cholesterol levels in human plasma. In this study, Nogo-B deficiency/inhibition not only promotes hepatic uptake of blood cholesterol but also facilitates cholesterol excretion. This study reports a strategy to lower cholesterol levels by inhibiting Nogo-B expression to promote hepatic cholesterol uptake and cholesterol excretion.

Summary: Obesity and fatty liver diseases—metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH)—affect over one-third of the global population and are exacerbated in individuals with reduced functional aldehyde dehydrogenase 2 (ALDH2), observed in approximately 560 million people. Current treatment to prevent disease progression to cancer remains inadequate, requiring innovative approaches. We observe that Aldh2−/− and Aldh2−/−Sptbn1+/− mice develop phenotypes of human metabolic syndrome (MetS) and MASH with accumulation of endogenous aldehydes such as 4-hydroxynonenal (4-HNE). Mechanistic studies demonstrate aberrant transforming growth factor β (TGF-β) signaling through 4-HNE modification of the SMAD3 adaptor SPTBN1 (β2-spectrin) to pro-fibrotic and pro-oncogenic phenotypes, which is restored to normal SMAD3 signaling by targeting SPTBN1 with small interfering RNA (siRNA). Significantly, therapeutic inhibition of SPTBN1 blocks MASH and fibrosis in a human model and, additionally, improves glucose handling in Aldh2−/− and Aldh2−/−Sptbn1+/− mice. This study identifies SPTBN1 as a critical regulator of the functional phenotype of toxic aldehyde-induced MASH and a potential therapeutic target.

Summary: Regulatory T cells (Tregs) suppress pro-inflammatory conventional T cell (Tconv) responses. As lipids impact cell signaling and function, we compare the lipid composition of CD4+ thymus-derived (t)Tregs and Tconvs. Lipidomics reveal constitutive enrichment of neutral lipids in Tconvs and phospholipids in tTregs. TNFR2-co-stimulated effector tTregs and Tconvs are both glycolytic, but only in tTregs are glycolysis and the tricarboxylic acid (TCA) cycle linked to a boost in fatty acid (FA) synthesis (FAS), supported by relevant gene expression. FA chains in tTregs are longer and more unsaturated than in Tconvs. In contrast to Tconvs, tTregs effectively use either lactate or glucose for FAS and rely on this process for proliferation. FASN and SCD1, enzymes responsible for FAS and FA desaturation, prove essential for the ability of tTregs to suppress Tconvs. These data illuminate how effector tTregs can thrive in inflamed or cancerous tissues with limiting glucose but abundant lactate levels.

Summary: Ferroptosis is a form of nonapoptotic cell death characterized by iron-dependent peroxidation of polyunsaturated phospholipids. However, much remains unknown about the regulators of ferroptosis. Here, using CRISPR-Cas9-mediated genetic screening, we identify protein arginine methyltransferase 1 (PRMT1) as a crucial promoter of ferroptosis. We find that PRMT1 decreases the expression of solute carrier family 7 member 11 (SLC7A11) to limit the abundance of intracellular glutathione (GSH). Moreover, we show that PRMT1 interacts with ferroptosis suppressor protein 1 (FSP1), a GSH-independent ferroptosis suppressor, to inhibit the membrane localization and enzymatic activity of FSP1 through arginine dimethylation at R316, thus reducing CoQ10H2 content and inducing ferroptosis sensitivity. Importantly, genetic depletion or pharmacological inhibition of PRMT1 in mice prevents ferroptotic events in the liver and improves the overall survival under concanavalin A (ConA) exposure. Hence, our findings suggest that PRMT1 is a key regulator of ferroptosis and a potential target for antiferroptosis therapeutics.

Summary: Metabolic reprogramming is crucial for activating innate immunity in macrophages, and the accumulation of immunometabolites is essential for effective defense against infection. The NAD+/NADH (ratio of nicotinamide adenine dinucleotide and its reduced counterpart) redox couple serves as a critical node that integrates metabolic pathways and signaling events, but how this metabolite couple engages macrophage activation remains unclear. Here, we show that the NAD+/NADH ratio serves as a molecular signal that regulates proinflammatory responses and type I interferon (IFN) responses divergently. Salmonella Typhimurium infection leads to a decreased NAD+/NADH ratio by inducing the accumulation of NADH. Further investigation shows that an increased NAD+/NADH ratio correlates with attenuated proinflammatory responses and enhanced type I IFN responses. Conversely, a decreased NAD+/NADH ratio is linked to intensified proinflammatory responses and restrained type I IFN responses. These results show that the NAD+/NADH ratio is an essential cell-intrinsic factor that orchestrates innate immunity, which enhances our understanding of how metabolites fine-tune innate immunity.

Summary: Calorie restriction (CR) extends lifespan and healthspan in diverse species. Comparing ad libitum- and CR-fed mice is challenging due to their significantly different feeding patterns, with CR-fed mice consuming their daily meal in 2 h and then subjecting themselves to a prolonged daily fast. Here, we examine how ad libitum- and CR-fed mice respond to tests performed at various times and fasting durations and find that the effects of CR—insulin sensitivity, circulating metabolite levels, and mechanistic target of rapamycin 1 (mTORC1) activity—result from the specific temporal conditions chosen, with CR-induced improvements in insulin sensitivity observed only after a prolonged fast, and the observed differences in mTORC1 activity between ad libitum- and CR-fed mice dependent upon both fasting duration and the specific tissue examined. Our results demonstrate that much of our understanding of the effects of CR are related to when, relative to feeding, we choose to examine the mice.

Physical activity is associated with beneficial adaptations in human and rodent metabolism. We studied over 50 complex traits before and after exercise intervention in middle-aged men and a panel of 100 diverse strains of female mice. Candidate gene analyses in three brain regions, muscle, liver, heart, and adipose tissue of mice indicate genetic drivers of clinically relevant traits, including volitional exercise volume, muscle metabolism, adiposity, and hepatic lipids. Although ∼33% of genes differentially expressed in skeletal muscle following the exercise intervention are similar in mice and humans independent of BMI, responsiveness of adipose tissue to exercise-stimulated weight loss appears controlled by species and underlying genotype. We leveraged genetic diversity to generate prediction models of metabolic trait responsiveness to volitional activity offering a framework for advancing personalized exercise prescription. The human and mouse data are publicly available via a user-friendly Web-based application to enhance data mining and hypothesis development.

Elucidating the transitional stages that define the pathway stem cells progress through during differentiation advances our understanding of biology and fosters the identification of therapeutic opportunities. However, distinguishing progenitor cells from other cell types and placing them in an epistatic pathway is challenging. This is exemplified in the adipocyte lineage, where the stromal vascular fraction (SVF) from adipose tissue is enriched for progenitor cells but also contains heterogeneous populations of cells. Single-cell RNA sequencing (scRNA-seq) has begun to facilitate the deconvolution of cell types in the SVF, and a hierarchical structure is emerging. Here, we use scRNA-seq to discover a population of CD31- CD45- cells in the SVF that are distinguished by a specific expression profile. Further, we place this population on an epistatic pathway upstream of the previously defined preadipocyte population. Finally, we discover functional properties of this population with broad implications, including revealing physiological mechanisms that regulate adipogenesis.

Cellular metabolism is tightly regulated by growth factor signaling, which promotes metabolic rewiring to support growth and proliferation. While growth factor-induced transcriptional and post-translational modes of metabolic regulation have been well defined, whether post-transcriptional mechanisms impacting mRNA stability regulate this process is less clear. Here, we present the ZFP36/L1/L2 family of RNA-binding proteins and mRNA decay factors as key drivers of metabolic regulation downstream of acute growth factor signaling. We quantitatively catalog metabolic enzyme and nutrient transporter mRNAs directly bound by ZFP36 following growth factor stimulation-many of which encode rate-limiting steps in metabolic pathways. Further, we show that ZFP36 directly promotes the mRNA decay of Enolase 2 (Eno2), altering Eno2 protein expression and enzymatic activity, and provide evidence of a ZFP36/Eno2 axis during VEGF-stimulated developmental retinal angiogenesis. Thus, ZFP36-mediated mRNA decay serves as an important mode of metabolic regulation downstream of growth factor signaling within dynamic cell and tissue states.

Enterocytes modulate the extent of postprandial lipemia by storing dietary fats in cytoplasmic lipid droplets (cLDs). We have previously shown that the integrin ligand MFGE8 links absorption of dietary fats with activation of triglyceride (TG) hydrolases that catabolize cLDs for chylomicron production. Here, we identify CES1D as the key hydrolase downstream of the MFGE8-αvβ5 integrin pathway that regulates catabolism of diet-derived cLDs. Mfge8 knockout (KO) enterocytes have reduced CES1D transcript and protein levels and reduced protein levels of the transcription factor HNF4γ. Both Ces1d and Hnf4γ KO mice have decreased enterocyte TG hydrolase activity coupled with retention of TG in cLDs. Mechanistically, MFGE8-dependent fatty acid uptake through CD36 stabilizes HNF4γ protein level; HNF4γ then increases Ces1d transcription. Our work identifies a regulatory network that regulates the severity of postprandial lipemia by linking dietary fat absorption with protein stabilization of a transcription factor that increases expression of hydrolases responsible for catabolizing diet-derived cLDs.

Nonalcoholic fatty liver disease (NAFLD) can be ameliorated by calorie restriction, which leads to the suppressed somatotroph axis. Paradoxically, the suppressed somatotroph axis is associated with patients with NAFLD and is correlated with the severity of fibrosis. How the somatotroph axis becomes dysregulated and whether the repressed somatotroph axis impacts liver damage during the progression of NAFLD are unclear. Here, we identify a regulatory branch of the hepatic integrated stress response (ISR), which represses the somatotroph axis in hepatocytes through ATF3, resulting in enhanced cell survival and reduced cell proliferation. In mouse models of NAFLD, the ISR represses the somatotroph axis, leading to reduced apoptosis and inflammation but decreased hepatocyte proliferation and exacerbated fibrosis in the liver. NAD+ repletion reduces the ISR, rescues the dysregulated somatotroph axis, and alleviates NAFLD. These results establish that the hepatic ISR suppresses the somatotroph axis to control cell fate decisions and liver damage in NAFLD.

Summary: Sphingolipid levels are crucial determinants of neurodegenerative disorders and therefore require tight regulation. The Orm protein family and ceramides inhibit the rate-limiting step of sphingolipid biosynthesis—the condensation of L-serine and palmitoyl-coenzyme A (CoA). The yeast isoforms Orm1 and Orm2 form a complex with the serine palmitoyltransferase (SPT). While Orm1 and Orm2 have highly similar sequences, they are differentially regulated, though the mechanistic details remain elusive. Here, we determine the cryoelectron microscopy structure of the SPT complex containing Orm2. Complementary in vitro activity assays and genetic experiments with targeted lipidomics demonstrate a lower activity of the SPT-Orm2 complex than the SPT-Orm1 complex. Our results suggest a higher inhibitory potential of Orm2, despite the similar structures of the Orm1- and Orm2-containing complexes. The high conservation of SPT from yeast to man implies different regulatory capacities for the three human ORMDL isoforms, which might be key for understanding their role in sphingolipid-mediated neurodegenerative disorders.

Summary: Tumor cells undergo uncontrolled proliferation driven by enhanced anabolic metabolism including glycolysis and glutaminolysis. Targeting these pathways to inhibit cancer growth is a strategy for cancer treatment. Critically, however, tumor-responsive T cells share metabolic features with cancer cells, making them susceptible to these treatments as well. Here, we assess the impact on anti-tumor T cell immunity and T cell exhaustion by genetic ablation of lactate dehydrogenase A (LDHA) and glutaminase1 (GLS1), key enzymes in aerobic glycolysis and glutaminolysis. Loss of LDHA severely impairs expansion of T cells in response to tumors and chronic infection. In contrast, T cells lacking GLS1 can compensate for impaired glutaminolysis by engaging alternative pathways, including upregulation of asparagine synthetase, and thus efficiently respond to tumor challenge and chronic infection as well as immune checkpoint blockade. Targeting GLS1-dependent glutaminolysis, but not aerobic glycolysis, may therefore be a successful strategy in cancer treatment, particularly in combination with immunotherapy.

Summary: Mesenchymal stem/stromal cell (MSC) therapies have had limited success so far in clinical trials due in part to heterogeneity in immune-responsive phenotypes. Therefore, techniques to characterize these properties of MSCs are needed during biomanufacturing. Imaging cell shape, or morphology, has been found to be associated with MSC immune responsivity—but a direct relationship between single-cell morphology and function has not been established. We used label-free differential phase contrast imaging and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to evaluate single-cell morphology and explore relationships with lipid metabolic immune response. In interferon gamma (IFN-γ)-stimulated MSCs, we found higher lipid abundances from the ceramide-1-phosphate (C1P), phosphatidylcholine (PC), LysoPC, and triglyceride (TAG) families that are involved in cell immune function. Furthermore, we identified differences in lipid signatures in morphologically defined MSC subpopulations. The use of single-cell optical imaging coupled with single-cell spatial lipidomics could assist in optimizing the MSC production process and improve mechanistic understanding of manufacturing process effects on MSC immune activity and heterogeneity.

Summary: Pancreatic ductal adenocarcinoma (PDAC) features substantial matrix stiffening and reprogrammed glucose metabolism, particularly the Warburg effect. However, the complex interplay between these traits and their impact on tumor advancement remains inadequately explored. Here, we integrated clinical, cellular, and bioinformatics approaches to explore the connection between matrix stiffness and the Warburg effect in PDAC, identifying CLIC1 as a key mediator. Elevated CLIC1 expression, induced by matrix stiffness through Wnt/β-catenin/TCF4 signaling, signifies poorer prognostic outcomes in PDAC. Functionally, CLIC1 serves as a catalyst for glycolytic metabolism, propelling tumor proliferation. Mechanistically, CLIC1 fortifies HIF1α stability by curbing hydroxylation via reactive oxygen species (ROS). Collectively, PDAC cells elevate CLIC1 levels in a matrix-stiffness-responsive manner, bolstering the Warburg effect to drive tumor growth via ROS/HIF1α signaling. Our insights highlight opportunities for targeted therapies that concurrently address matrix properties and metabolic rewiring, with CLIC1 emerging as a promising intervention point.

Summary: Down syndrome (DS), the genetic condition caused by trisomy 21 (T21), is characterized by delayed neurodevelopment, accelerated aging, and increased risk of many co-occurring conditions. Hypoxemia and dysregulated hematopoiesis have been documented in DS, but the underlying mechanisms and clinical consequences remain ill defined. We report an integrative multi-omic analysis of ∼400 research participants showing that people with DS display transcriptomic signatures indicative of elevated heme metabolism and increased hypoxic signaling across the lifespan, along with chronic overproduction of erythropoietin, elevated biomarkers of tissue-specific hypoxia, and hallmarks of stress erythropoiesis. Elevated heme metabolism, transcriptional signatures of hypoxia, and stress erythropoiesis are conserved in a mouse model of DS and associated with overexpression of select triplicated genes. These alterations are independent of the hyperactive interferon signaling characteristic of DS. These results reveal lifelong dysregulation of key oxygen-related processes that could contribute to the developmental and clinical hallmarks of DS.

Summary: Macrophage metabolic plasticity is central to inflammatory programming, yet mechanisms of coordinating metabolic and inflammatory programs during infection are poorly defined. Here, we show that type I interferon (IFN) temporally guides metabolic control of inflammation during methicillin-resistant Staphylococcus aureus (MRSA) infection. We find that staggered Toll-like receptor and type I IFN signaling in macrophages permit a transient energetic state of combined oxidative phosphorylation (OXPHOS) and aerobic glycolysis followed by inducible nitric oxide synthase (iNOS)-mediated OXPHOS disruption. This disruption promotes type I IFN, suppressing other pro-inflammatory cytokines, notably interleukin-1β. Upon infection, iNOS expression peaks at 24 h, followed by lactate-driven Nos2 repression via histone lactylation. Type I IFN pre-conditioning prolongs infection-induced iNOS expression, amplifying type I IFN. Cutaneous MRSA infection in mice constitutively expressing epidermal type I IFN results in elevated iNOS levels, impaired wound healing, vasculopathy, and lung infection. Thus, kinetically regulated type I IFN signaling coordinates immunometabolic checkpoints that control infection-induced inflammation.

Summary: Malaria is initiated as Plasmodium sporozoites are injected into the dermis when an infected mosquito probes on a vertebrate host for a blood meal. Factors in the mosquito saliva, such as AgTRIO, can alter the ability of Anopheles gambiae to transmit Plasmodium. We therefore used CRISPR-Cas9-mediated genome editing to generate AgTRIO knockout (KO) A. gambiae and examined the ability of these mosquitoes to probe on a vertebrate host. AgTRIO KO mosquitoes showed a diminished host probing capacity and required repetitive probing to locate a blood resource to complete a blood meal. This increased probing resulted in enhanced Plasmodium transmission to the vertebrate host. Our data demonstrate the importance of the A. gambiae saliva protein AgTRIO in probing and its influence on the ability of mosquitoes to transmit malaria.

Summary: Cancer cachexia is a prevalent and often fatal wasting condition that cannot be fully reversed with nutritional interventions. Muscle atrophy is a central component of the syndrome, but the mechanisms whereby cancer leads to skeletal muscle atrophy are not well understood. We performed single-nucleus multi-omics on skeletal muscles from a mouse model of cancer cachexia and profiled the molecular changes in cachexic muscle. Our results revealed the activation of a denervation-dependent gene program that upregulates the transcription factor myogenin. Further studies showed that a myogenin-myostatin pathway promotes muscle atrophy in response to cancer cachexia. Short hairpin RNA inhibition of myogenin or inhibition of myostatin through overexpression of its endogenous inhibitor follistatin prevented cancer cachexia-induced muscle atrophy in mice. Our findings uncover a molecular basis of muscle atrophy associated with cancer cachexia and highlight potential therapeutic targets for this disorder.

Summary: Previous studies have demonstrated that gut microbiota dysbiosis promotes the development of mastitis. The interaction of the vagus nerve and gut microbiota endows host homeostasis and regulates disease development, but whether the vagus nerve participates in the pathogenesis of mastitis is unclear. Here, vagotomized mice exhibit disruption of the blood-milk barrier and mammary gland inflammation. Notably, mastitis and barrier damage caused by vagotomy are dependent on the gut microbiota, as evidenced by antibiotic treatment and fecal microbiota transplantation. Vagotomy significantly alters the gut microbial composition and tryptophan metabolism and reduces the 5-hydroxyindole acetic acid (5-HIAA) level. Supplementation with 5-HIAA alleviates vagotomy-induced mastitis, which is associated with the activation of the aryl hydrocarbon receptor (AhR) and subsequent inhibition of the NF-κB pathway. Collectively, our findings indicate the important role of the vagus-mediated gut-mammary axis in the pathogenesis of mastitis and imply a potential strategy for the treatment of mastitis by targeting the vagus-gut microbiota interaction.

Summary: Growth and differentiation factor 15 (GDF15) has recently emerged as a weight loss and insulin-sensitizing factor. Growing evidence also supports a role for GDF15 as a physiological, exercise-induced stress signal. Here, we tested whether GDF15 is required for the insulin-sensitizing effects of exercise in mice and humans. At baseline, both under a standard nutritional state and high-fat feeding, GDF15 knockout (KO) mice display normal glucose tolerance, systemic insulin sensitivity, maximal speed, and endurance running capacity when compared to wild-type littermates independent of sex. When submitted to a 4-week exercise training program, both lean and obese wild-type and GDF15 KO mice similarly improve their endurance running capacity, glucose tolerance, systemic insulin sensitivity, and peripheral glucose uptake. Insulin-sensitizing effects of exercise training were also unrelated to changes in plasma GDF15 in humans. In summary, we here show that GDF15 is dispensable for the insulin-sensitizing effects of chronic exercise.