An imbalance of DNA damage over DNA repair contributes to the genomic instability that drives aging and numerous age-related diseases. While numerous DNA repair mechanisms have been elucidated over decades of study, little is known about the contribution of metabolism to genomic stability. We report that adipose triglyceride lipase (ATGL), a primary lipolytic enzyme, promotes DNA repair. We show that lipid droplets (LDs) accumulate in response to DNA damage and that inhibition of LD biogenesis before genotoxic stress increases the persistence of DNA damage. Overexpression of ATGL (increasing lipolysis) enhances DNA repair in response to etoposide and ionizing radiation, thus reducing DNA damage burden. Mechanistically, ATGL promotes bulk acetylation of chromatin-bound proteins and blockade of the histone acetyltransferase p300 negates these effects. Further, ATGL-induced DNA repair attenuates the long-term consequences of DNA damage, and reducing senescence and enhancing viability. Overall, these studies reveal a novel role for LDs and LD proteins in DNA damage and repair, thus unveiling a mechanism through which lipid metabolism contributes to genomic stability.

Background/Objectives: Circadian misalignment, including mistimed sleep or eating, is associated with altered glucose metabolism. The importance of eating window timing for time-restricted eating (TRE) is increasingly recognized. This secondary analysis examined associations between meal to sleep timing intervals and glycemic parameters in individuals with obesity across three dietary interventions [TRE, CR: caloric restriction, and UE: unrestricted eating]. Methods: Participants aged 18-65 years with obesity were randomized to a 12-week intervention: TRE (8 h eating window), CR (15% reduction in daily caloric intake), or UE (usual eating habits). CGM and actigraphy were assessed over two weeks at baseline and end-intervention. Mixed effects models examined associations between continuous glucose monitoring (CGM) outcomes and two intervals: last meal to sleep onset (PM meal-Sleep) and awakening to first meal (Awake-AM meal). Results: Each hour increase in the Awake-AM meal interval was associated with lower overnight (1 AM-5 AM) average glucose, lower glycemic variability, lower %time > 180 mg/dL, and greater %time < 70 mg/dL. Each hour increase in the PM meal-Sleep interval was associated with lower overnight (1 AM-5 AM) average glucose. Both associations persisted after adjustment for baseline sleep duration, HbA1c, and randomization assignment. Conclusions: In individuals with obesity, morning (Awake-AM meal interval) and evening (PM meal-Sleep interval) fasting relative to sleep were differentially associated with glycemic control. These findings highlight the relevance of eating and sleep timing to glycemic parameters and may inform eating window selection for individuals practicing TRE.

BACKGROUND:Time-restricted eating (TRE) may be as effective as an energy-restricted (ER) diet for weight loss. However, little is known about the effects of TRE on eating patterns and dietary intake. OBJECTIVE:The aims of this study were to examine the relative effects of TRE, ER, and unrestricted eating (UE) diets on eating patterns and dietary intake. DESIGN:This study is a secondary analysis of data from a randomized controlled trial carried out between October 2020 and October 2023. Over this period, 88 participants were randomized to a TRE, ER, or UE diet group. PARTICIPANTS/SETTING:Adults with obesity in the Minneapolis-Saint Paul, Minnesota, metropolitan area who completed study baseline and follow-up measures of dietary intake (n = 73). INTERVENTION:The interventions were (1) TRE with an 8-hour self-chosen window with ad libitum diet; (2) ER diet with 15% reduction of energy intake; or (3) UE in which self-monitoring of food intake was encouraged with no specific change to eating recommended. The intervention period was 12 weeks. MAIN OUTCOME MEASURES:Outcomes included meals eaten and intake of vegetables, fruit, dairy, protein foods, grains, energy, added sugars, saturated fat, sodium, dietary fiber, and potassium. STATISTICAL ANALYSES:Multivariate linear regression analyses were carried out to compare the change in food and nutrient intake between experimental groups. Logistic mixed-effects models were constructed to examine the change in meals eaten. RESULTS:The TRE group ate fewer daily meals at end-intervention (-1.1 meals/day; 95% confidence interval [CI], -1.6, -0.7) compared with baseline, whereas the ER and UE groups did not experience a change in eating occasions. Those in the TRE group were less likely to report eating breakfast during end-intervention compared with baseline (odds ratio [OR], 0.13; 95% CI, 0.05, 0.33), whereas no statistically significant change in behavior was identified for the ER (OR, 1.02; 95% CI, 0.41, 2.55) or UE (OR, 0.68; 95% CI, 0.28, 1.68) groups. Between baseline and end-intervention those in the TRE group had a decrease in intake of energy (-469 kcal/day; 95% CI, -681, -257), saturated fat (-8.5 g/day; 95% CI, -12.9, -4.1), potassium (-496 mg/day; 95% CI, -729, -263), and total (-1.7 ounce equivalents/day; 95% CI, -2.9, -0.6) and refined grains (-1.6 ounce equivalents; 95% CI, -2.6, -0.6). These changes were more marked compared with changes in the UE group. There were no statistically significant differences found between those in the TRE and ER groups. CONCLUSIONS:Findings suggest that TRE with an 8-hour window and ad libitum intake may have similar effects on food and nutrient intake as an energy-restricted diet.

Lipid metabolism and storage are highly compartmentalized processes. Key organelles defined to govern lipid synthesis (ER), storage (lipid droplets, LDs), and catabolism (mitochondria) work in synchrony to coordinate lipid metabolic flux. Interactions between these organelles play important roles in metabolite exchange and signaling that vary in response to physiological conditions. Alterations in organelle crosstalk or imbalances between anabolic and catabolic pathways are commonly observed in diseased states, including metabolic dysfunction-associated steatotic liver disease (MASLD). While many studies have characterized two-organelle interactions (e.g., LD mitochondria), there is a general lack of consideration of how the presence of other organelles impacts the function of these contacts. This review aims to provide a concise summary of the regulation, function, and complexity of how these organelle interactions compartmentalize hepatic lipid metabolism.

Geroscience research benefits from interdisciplinary approaches, team science, and collaborations, which collectively facilitate the discovery of aging mechanisms and their translation into tangible, clinical interventions. Since its inception in 2019, the Midwest Aging Consortium (MAC) has provided an engaging platform for aging researchers in the United States' Midwest to connect, collaborate, and exchange ideas. The Sixth Annual Research Symposium of the MAC held at the Mayo Clinic in Rochester, Minnesota, in April 2025 highlighted the continued impact of the MAC in bringing together aging researchers, including many trainees and early career investigators, into a collaborative environment. This record-setting event featured interdisciplinary research on key aging mechanisms, including lipid metabolism, mitochondrial dysfunction, stress response, cellular senescence, and immune adaptations across organ systems. New therapeutic concepts and clinical trial approaches were presented. Cutting-edge methodologies including single-cell and spatial transcriptomics, metabolomics, and organoid cultures, to dissect aging process in tissue-specific and systemic contexts also were presented. Overall, the MAC symposium underscored the translational potential of geroscience and reinforced the MAC's mission to accelerate aging research through regional collaborations and innovation.

OBJECTIVE:Metabolic improvements may precede weight loss. We compared the effects of self-selected 8-h time-restricted eating (TRE), 15% caloric restriction (CR), and unrestricted eating (UE) on weight, body composition, caloric intake, glycemic measures, and metabolic flexibility. METHODS:In this 12-week randomized-controlled trial, we measured weight (primary outcome), body composition (dual-energy x-ray absorptiometry/magnetic resonance imaging), caloric intake (24-h recall), metabolic flexibility (indirect calorimetry during hyperinsulinemic-euglycemic clamp), and glycemic measures (hemoglobin A1c, hyperinsulinemic-euglycemic clamp, continuous glucose monitoring). RESULTS:Of the 88 enrolled participants, 81 (92%) completed the trial (mean [SD], age, 43.2 [10.5] years, BMI, 36.2 [5.1] kg/m2; 54.5% female, 84.1% White). Final eating windows were 9.8 h (95% CI: 9.0 to 10.6) for TRE, 12.9 h (95% CI: 11.9 to 13.9) for CR, and 11.8 h (95% CI: 11.0 to 12.7) for UE. Compared with UE (n = 29), weight changes were -1.4 kg (95% CI: -4.5 to 1.7; p = 0.53) with TRE (n = 30) and -2.5 kg (95% CI: -5.8 to 0.8; p = 0.18) with CR (n = 29). TRE showed lower metabolic flexibility than CR (-0.041 [95% CI: -0.080 to -0.002]). Weight, body composition, caloric intake, and glycemic measures were similar among groups. Eating window reduction correlated with decreased caloric intake and visceral fat. CONCLUSIONS:In a 12-week intervention, TRE did not lead to significant improvements in weight, average body composition, or glycemic or metabolic measures compared with CR or UE.

Metabolic adaptation to fasting may have conferred survival advantage to early humans and predicts weight gain caused by overnutrition in modern societies. Fasting suppresses brown adipose tissue (BAT) thermogenesis; however, it is unclear how BAT rewires cellular metabolism to balance between energy conservation and heat generation. Here, we report that BAT in mice under fasting and cold challenge consumed ketone bodies, specifically acetoacetate (AcAc). Ablating liver ketogenesis decreased, while enhancing hepatic AcAc output defended, body temperature in mice facing the dual challenge. Using stable isotope tracing in brown adipocytes in vitro combined with quantitative analysis of metabolic fluxes and lipidomics in BAT from genetic mouse models, we disentangled the two metabolic fates of AcAc - terminal oxidation in the mitochondria and lipid biosynthesis in the cytosol. Notably, AcAc-sourced carbon preferentially supported polyunsaturated fatty acid synthesis in BAT, linking to the positive impact of intermittent fasting on lipid profiles in both mice and humans. Therefore, ketone body utilization by thermogenic adipocytes contributes to metabolic resilience of mammals and can be targeted to optimize benefits of dietary regimens.

Glycophagy is the autophagic degradation of glycogen by the enzyme acid alpha-glucosidase (GAA). Although GAA inhibitors improve metabolic health by inhibiting GAA in the intestine, it is not clear if GAA inhibition in peripheral tissues such as the liver is metabolically beneficial. This study tested if the heterozygous knockout of GAA (HetKO-GAA) alters liver metabolism and metabolic health in mice fed a low-fat diet or a high-fat diet to induce obesity. HetKO-GAA mice fed either diet did not have altered body weight, glucose tolerance, insulin action, energy expenditure, substrate metabolism, liver glucose output, or liver triglycerides compared to control wildtype mice. A liver spatial transcriptomics analysis revealed that high-fat diet feeding reduced the gene abundance of predominantly metabolic pathways in both periportal and perivenous hepatocytes, and uniquely reduced ribosome gene abundance in perivenous hepatocytes. HetKO-GAA mice did not have significantly altered transcriptomes in periportal or perivenous hepatocytes compared to wildtype mice. In conclusion, heterozygous GAA knockout is nonconsequential on metabolism and metabolic health in high-fat diet induced obesity. Spatial transcriptomics revealed alterations in the transcriptome of periportal and perivenous hepatocytes from high-fat diet induced obese mice, highlighting novel targets that could be exploited to improve metabolic health in obesity.

Environmental factors may affect gene expression through epigenetic modifications of histones and transcription factors. Here, we report that cellular uptake of sorbate, a common food preservative, induces lysine sorbylation (Ksor) in mammalian cells and tissue mediated by the noncanonical activities of class I histone deacetylases (HDAC1-3). We demonstrated that HDAC1-3 catalyze sorbylation upon sorbate uptake and desorbylation in the absence of sorbate both in vitro and in cells. Sorbate uptake in mice livers significantly induced histone Ksor, correlating with decreased expressions of inflammation-response genes. Accordingly, sorbate treatment in macrophage RAW264.7 cells upon lipopolysaccharide (LPS) stimulation dose-dependently down-regulated proinflammatory gene expressions and nitric oxide production. Proteomic profiling identified RelA, a component of the NF-κB complex, and its interacting proteins as bona fide Ksor targets and sorbate treatment significantly decreased NF-κB transcriptional activities in response to LPS stimulation in RAW264.7 cells. Together, our study demonstrated a noncanonical mechanism of sorbate uptake in regulating epigenetic histone modifications and inflammatory gene expression.

In the era of big data in scientific research, there is a necessity to leverage techniques which reduce human effort in labeling and categorizing large datasets by involving sophisticated machine tools. To combat this problem, we present a novel, general purpose model for 3D segmentation that leverages patch-wise adversariality and Long Short-Term Memory to encode sequential information. Using this model alongside citizen science projects which use 3D datasets (image cubes) on the Zooniverse platforms, we propose an iterative human-machine optimization framework where only a fraction of the 2D slices from these cubes are seen by the volunteers. We leverage the patch-wise discriminator in our model to provide an estimate of which slices within these image cubes have poorly generalized feature representations, and correspondingly poor machine performance. These images with corresponding machine proposals would be presented to volunteers on Zooniverse for correction, leading to a drastic reduction in the volunteer effort on citizen science projects. We trained our model on ~2300 liver tissue 3D electron micrographs. Lipid droplets were segmented within these images through human annotation via the `Etch A Cell - Fat Checker' citizen science project, hosted on the Zooniverse platform. In this work, we demonstrate this framework and the selection methodology which resulted in a measured reduction in volunteer effort by more than 60%. We envision this type of joint human-machine partnership will be of great use on future Zooniverse projects.

Metabolic and environmental factors may impact gene expression through the production of active metabolites and epigenetic modifications of histones and transcription factors. In this study, we discovered that cellular uptake of sorbate, an FDA-approved and widely used food preservative, can induce lysine sorbylation (Ksor), a new posttranslational modification and epigenetic mark. We identified over 40 Ksor sites on core histones from mammalian cells and tissue upon sorbate uptake and further showed that the dynamics of histone Ksor could be regulated by the non-canonical activities of Class I histone deacetylases (HDAC1-3). We demonstrated that Class I HDACs catalyzed sorbylation upon sorbate uptake and desorbylation in the absence of sorbate both in vitro and in vivo. Sorbate uptake in mice livers led to a significant increase in histone Ksor without affecting overall histone acetylation, which correlated with the decreased expression of genes in inflammation signaling pathways. Accordingly, sorbate treatment in macrophage RAW264.7 cells upon LPS stimulation dose-dependently downregulated the expression of proinflammatory genes and production of nitric oxide. Global proteomic profiling revealed widespread lysine sorbylation substrates in diverse metabolic and signaling pathways and identified RelA (p65), a component of the NF-kB complex, and its interacting proteins as bona fide Ksor targets. Sorbate treatment significantly decreased NF-kB transcriptional activities in response to LPS stimulation in RAW264.7 cells. Taken together, our study demonstrated a non-canonical mechanism of sorbate uptake in regulating epigenetic histone modifications and inflammatory gene expression. ### Competing Interest Statement The authors have declared no competing interest.

>Identifying cellular mechanisms that underlie senescence development in vivo has been challenging in the field of aging research. In a recent article published in Nature, Byrns et al. identified a population of naturally occurring senescent glial cells that emerge in response to aging-associated neuronal mitochondrial dysfunction. These senescent glial cells promote the accumulation of lipid droplets(LDs) in non-senescent glial cells and can be targeted to extend healthspan.

Hepatic steatosis, the buildup of neutral lipids in lipid droplets (LDs), is commonly referred to as metabolic dysfunction-associated steatotic liver disease when alcohol or viral infections are not involved. Metabolic dysfunction-associated steatotic liver disease encompasses simple steatosis and the more severe metabolic dysfunction-associated steatohepatitis, characterized by inflammation, hepatocyte injury, and fibrosis. Previously viewed as inert markers of disease, LDs are now understood to play active roles in disease etiology and have significant nonpathological and pathological functions in cell signaling and function. These dynamic properties of LDs are tightly regulated by hundreds of proteins that coat the LD surface, controlling lipid metabolism, trafficking, and signaling. The following review highlights various facets of LD biology with the primary goal of discussing key mechanisms through which LDs promote the development of advanced liver diseases, including metabolic dysfunction-associated steatohepatitis.

Background and Aims: For patients with obesity and metabolic syndrome, bariatric procedures such as vertical sleeve gastrectomy (VSG) have a clear benefit in ameliorating metabolic dysfunction-associated steatohepatitis (MASH). While the effects of bariatric surgeries have been mainly attributed to nutrient restriction and malabsorption, whether immuno-modulatory mechanisms are involved remains unclear. Approach and Result: Using murine models, we report that VSG ameliorates MASH progression in a weight loss-independent manner. Single-cell RNA sequencing revealed that hepatic lipid-associated macrophages (LAMs) expressing the triggering receptor expressed on myeloid cells 2 (TREM2) repress inflammation and increase their lysosomal activity in response to VSG. Remarkably, TREM2 deficiency in mice ablates the reparative effects of VSG, suggesting that TREM2 is required for MASH resolution. Mechanistically, TREM2 prevents the inflammatory activation of macrophages and is required for their efferocytic function. Conclusions: Overall, our findings indicate that bariatric surgery improves MASH through a reparative process driven by TREM2+ macrophages, providing insights into the mechanisms of disease reversal that may result in new therapies and improved surgical interventions.

Intramyocellular triglyceride (IMTG) level correlates with insulin resistance. Paradoxically, trained humans and obese, sedentary, insulin-resistant humans have high IMTG levels despite discrepant clinical phenotypes. We hypothesize that higher IMTG turnover in trained humans explains this paradox. Methods: Obese, insulin-resistant subjects [n=47, mean (SD), BMI:36.2 kg/m2(5.7), VO2max 25.4 ml/kg/min (5.7)] and lean trained subjects [n=15, BMI:22.2 kg/m2(1.8), VO2max 55ml/kg/min (10.1)] were fasted overnight. Two muscle biopsies (Bx) were acquired during a pulse-chase experiment using [U-13C]palmitate and [9-2H]palmitate infusions (6 h each), overlapping by 1 hour. Bx#1 was performed during the infusion overlap [last hour of 6 h [U-13C]palmitate infusion, 1 hour after starting [9-2H]palmitate. Bx#2 was performed at study conclusion [last hour of [9-2H]palmitate infusion, 6 hours after stopping [U-13C]palmitate]. Palmitate enrichment and concentration were measured. [9-2H]palmitate IMTG incorporation at Bx#1 and [U-13C] IMTG loss at Bx#2 indicated the interplay between plasma and muscle fatty acids. Results: Palmitate IMTG incorporation positively correlated between measures of IMTG turnover and negatively with insulin sensitivity. No correlation seen for VO2max/BMI. Conclusion: Muscle-level IMTG measures dictates higher resting IMTG turnover more than training related phenotype. Disclosure L.S.Chow: Research Support; Dexcom, Inc. A.Bantle: None. A.C.Alvear: None. D.G.Mashek: None. M.D.Jensen: Other Relationship; Novo Nordisk, Elsevier. Funding National Institutes of Health (R01DK098203)

Organelle interactions play a significant role in compartmentalizing metabolism and signaling. Lipid droplets (LDs) interact with numerous organelles, including mitochondria, which is largely assumed to facilitate lipid transfer and catabolism. However, quantitative proteomics of hepatic peridroplet mitochondria (PDM) and cytosolic mitochondria (CM) reveals that CM are enriched in proteins comprising various oxidative metabolism pathways, whereas PDM are enriched in proteins involved in lipid anabolism. Isotope tracing and super-resolution imaging confirms that fatty acids (FAs) are selectively trafficked to and oxidized in CM during fasting. In contrast, PDM facilitate FA esterification and LD expansion in nutrient-replete medium. Additionally, mitochondrion-associated membranes (MAM) around PDM and CM differ in their proteomes and ability to support distinct lipid metabolic pathways. We conclude that CM and CM-MAM support lipid catabolic pathways, whereas PDM and PDM-MAM allow hepatocytes to efficiently store excess lipids in LDs to prevent lipotoxicity.

AbstractNutritional interventions often rely on subjective assessments of energy intake (EI), but these are susceptible to measurement error. To introduce an accelerometer-based intake-balance method for assessing EI using data from a time-restricted eating (TRE) trial. Nineteen participants with overweight/obesity (25–63 years old; 16 females) completed a 12-week intervention (NCT03129581) in a control group (unrestricted feeding; n 8) or TRE group (n 11). At the start and end of the intervention, body composition was assessed by dual-energy X-ray absorptiometry (DXA) and daily energy expenditure (EE) was assessed for 2 weeks via wrist-worn accelerometer. EI was back-calculated as the sum of net energy storage (from DXA) and EE (from accelerometer). Accelerometer-derived EI estimates were compared against estimates from the body weight planner of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Mean EI for the control group declined by 138 and 435 kJ/day for the accelerometer and NIDDK methods, respectively (both P ≥ 0·38), v. 1255 and 1469 kJ/day, respectively, for the TRE group (both P < 0·01). At follow-up, the accelerometer and NIDDK methods showed excellent group-level agreement (mean bias of −297 kJ/day across arms; standard error of estimate 1054 kJ/day) but high variability at the individual level (limits of agreement from −2414 to +1824 kJ/day). The accelerometer-based intake-balance method showed plausible sensitivity to change, and EI estimates were biologically and behaviourally plausible. The method may be a viable alternative to self-report EI measures. Future studies should assess criterion validity using doubly labelled water.

Objective:Decreased insulin sensitivity and impairment of beta-cell function predate and predict development of type 2 diabetes mellitus. Time-restricted eating (TRE) might have a benefit for these parameters. The objective of this pilot study was to investigate this possibility. Methods:Secondary analysis of a randomized controlled trial comparing 12 weeks of TRE (8-hour eating window) to unrestricted eating (non-TRE) was performed. Participants were adults with overweight or obesity and without diabetes. Two-hour oral glucose tolerance testing was performed at baseline and end-intervention. Glucose tolerance test-derived measures of insulin sensitivity, insulin secretion, and beta-cell function were compared between groups. Results:Participants (17 women/3 men with mean [SD] age 45.5 [12.1] years and BMI 34.1 [7.5] kg/m(2)) with a prolonged eating window (15.4 [0.9] hours) were randomized to TRE (n = 11) or non-TRE (n = 9). The quantitative insulin sensitivity check index (QUICKI), Stumvoll index, Avignon index, insulinogenic index, insulin area under the curve/glucose area under the curve, and oral disposition index did not differ between the TRE and non-TRE groups at end-intervention. Conclusions:In adults with overweight or obesity and without diabetes, TRE did not significantly alter insulin sensitivity, insulin secretion, or beta-cell function over a 12-week intervention. Whether TRE is beneficial in adults with prediabetes or type 2 diabetes mellitus warrants further investigation.

Acyl-CoA thioesterase 1 (ACOT1) catalyzes the hydrolysis of long-chain acyl-CoAs to free fatty acids and CoA and is typically upregulated in obesity. Whether targeting ACOT1 in the setting of high-fat diet-induced (HFD-induced) obesity would be metabolically beneficial is not known. Here we report that male and female ACOT1KO mice are partially protected from HFD-induced obesity, an effect associated with increased energy expenditure without alterations in physical activity or food intake. In males, ACOT1 deficiency increased mitochondrial uncoupling protein-2 (UCP2) protein abundance while reducing 4-hydroxynonenal, a marker of oxidative stress, in white adipose tissue and liver of HFD-fed mice. Moreover, concurrent knockdown (KD) of UCP2 with ACOT1 in hepatocytes prevented increases in oxygen consumption observed with ACOT1 KD during high lipid loading, suggesting that UCP2-induced uncoupling may increase energy expenditure to attenuate weight gain. Together, these data indicate that targeting ACOT1 may be effective for obesity prevention during caloric excess by increasing energy expenditure.

Fig. S1. Phenotypic and metabolic parameters are influenced by Ex and CR. Fig. S2. CR modulates additional markers of hepatic inflammation and immune cell infiltration. Fig. S3. CR causes divergence of genes in comparison to CTL mice. Fig. S4. CR affects gene signature pathways and networks associated with hepatic inflammation and metabolism. Table S1. Description of components (g/Kg) and macronutrient content (% kcal) of diets.