Metabolic Fuels Research Articles

9179 Type 2 Diabetes Alters Metabolic Fuel Selection During Intermittent Fasting

Abstract Disclosure: M.O. Conn: None. D.M. Marko: None. J.D. Schertzer: None. Type 2 Diabetes Alters Metabolic Fuel Selection During Intermittent Fasting Diabetes is characterized by elevated blood glucose resulting from defective insulin secretion and/or insulin resistance. Intermittent fasting, a popular weight loss strategy involving periodic reduction of caloric intake, can improve glycemia. Fasting shifts metabolism from carbohydrates to free fatty acids and ketones. However, high blood insulin can inhibit lipolysis and alter metabolic substrate selection in prediabetes, resulting in muscle catabolism to maintain energy homeostasis. Clinical studies have observed a significant decrease in muscle mass in subjects with obesity and diabetes. Our research aims to characterize lean mass versus fat loss after intermittent fasting in a mouse model of obesity and type 2 diabetes (T2D) and investigate the role of muscle alanine catabolism. We hypothesized that intermittent fasting would promote less lipolysis and more muscle alanine catabolism, causing more muscle loss in diabetic mice than controls. We compared male db/db mice manifesting obesity, hyperglycemia, and hyperinsulinemia to age-matched db/+ (control) mice. Our lab established a 5:2 repeated fasting protocol of ad-libitum access to food for 5 days a week and 2 days of fasting on non-consecutive days. Blood glucose was monitored weekly in fed and fasted states to assess glycemic control. While intermittent fasting lowered fasted blood glucose in both groups, no significant body weight or metabolic tissue mass changes were observed. Metabolic cage data demonstrated increased reliance on fat-based substrates for energy in control mice that underwent intermittent fasting during feeding and fasting periods. Diabetic mice did not show significant changes in the fasted state, but intermittent fasting led to increased reliance on carbohydrate oxidation during re-feeding periods, indicating impaired metabolic flexibility. After 10 weeks, the mice were sacrificed, and metabolic tissue histology (adipose, liver, skeletal muscle) will be performed. We will also analyze serum markers (alanine, fatty acids, glycerol, glucose, insulin) and the activity of the metabolic enzyme alanine transaminase (ALT) in the muscle and liver. This experiment will improve our understanding of how lipolysis and protein breakdown in muscle regulate lean mass versus fat mass loss in obesity and T2D, leading to more effective tailoring of fasting to specific populations. Presentation: 6/3/2024

Harnessing nucleotide metabolism and immunity in cancer: a tumour microenvironment perspective

The tumour microenvironment (TME) is a dynamic nexus where cancer cell metabolism and the immune system intricately converge, with nucleotide metabolism (NM) playing a pivotal role. This review explores the critical function of NM in cancer cell proliferation and its profound influence on the TME and immune landscape. NM is essential for DNA and RNA synthesis and is markedly upregulated in cancer cells to meet the demands of rapid growth. This metabolic rewiring fuels cancer progression, but also shapes the TME, impacting the function and viability of immune cells. The altered nucleotide milieu in the TME can suppress immune response, aiding cancer cell evasion from immune surveillance. Drug discoveries in the field of NM have revealed different therapeutic strategies, including inhibitors of nucleotide synthesis and drugs targeting salvage pathways, which are discussed thoroughly in this review. Furthermore, the emerging strategy of combining NM‐targeted therapies with immunotherapies is emphasised, particularly their effect on sensitising tumours to immune checkpoint inhibitors and enhancing overall treatment efficacy. The Human Genome Project paved the way for personalised medicine, countering the established ‘one size fits all’ approach to cancer treatment. Advances in understanding the TME and NM have spurred interest in personalised therapeutic strategies. This review highlights the potential of leveraging individual tumour metabolic profiles to guide treatment selection, aiming to optimise efficacy and minimise adverse effects. The strategic importance of targeting NM in cancer therapy and its synergistic potential with immunotherapies offers a path towards more effective and personalised cancer treatments.

Metabolic pathways that mediate the effects of food deprivation on reproductive behavior in female Drosophila melanogaster.

In most species studied, energy deficits inhibit female reproductive behavior, but the location and nature of energy sensors and how they affect behavior are unknown. Progress has been facilitated by using Drosophila melanogaster, a species in which reproduction and food availability are closely linked. Adult males and females were either fed or food deprived (FD) and then tested in an arena with a fed, opposite-sex conspecific with no food in the testing arena. Only FD females (not FD males) significantly decreased their copulation rate and increased their copulation latency, and the effects of FD were prevented in females fed either yeast alone or glucose alone, but not sucralose alone, cholesterol alone, or amino acids alone. It is well-known that high-fat diets inhibit copulation rate in this species, and the effects of FD on copulation rate were mimicked by treatment with an inhibitor of glucose but not free fatty acid oxidation. The availability of oxidizable glucose was a necessary condition for copulation rate in females fed either yeast alone or fed a nutritive fly medium, which suggests that the critical component of yeast for female copulation rate is oxidizable glucose. Thus, female copulation rate in D. melanogaster is sensitive to the availability of oxidizable metabolic fuels, particularly the availability of oxidizable glucose or substrates/byproducts of glycolysis.NEW & NOTEWORTHY Copulation rate was decreased in food-deprived female but not in male adults when tested without food in the testing arena. Copulation rate was 1) maintained by feeding glucose alone, yeast alone, nutritive medium lacking yeast, but not sucralose, amino acids, or cholesterol alone; 2) decreased by inhibition of glycolysis in females fed either nutritive medium or yeast alone; and 3) not affected by inhibition of fatty acid oxidation. Thus, female copulation rate was linked to glycolytic status.

Paternal influence on pregnancy: Setting the precedence

According to sociologist, Sylvia patriarchy is “a system of social structures and practices in which men dominate, oppress, and exploit women.” Derived from the Greek word patriarkhēs, patriarchy means “the rule of the father.” American sociologist Allan Johnson further mentions that patriarchy is a kind of society in which even though men and women participate, but is male-privileged, maledominated, male-identified, and male-centered. Apart from the sociologist’s point of view of society, it seems that developmental programs in biology also have a patriarchal trend. At least, that’s what is reported from several studies recently. Lopez-Tello et al., reported a paternal insulinlike growth factor 2 (Igf2)-related selective trafficking of maternal resources toward the fetus for its development. Metabolic demands for the fetus are enhanced during pregnancy. It is, therefore, observed that there is a relatively greater shunting of metabolic fuels toward the fetus to increase nutrient availability, more than it is perhaps allowed by the maternal system. The placenta assists in this shuttle by promoting insulin resistance, which leads to glucose intolerance in the mother. This glucose is now made available to the fetal compartments. The paternal Igf2 gene undergoes genomic imprinting, and only the copy inherited from the father is active. Paternally active Igf2 expressed in placental endocrine cells directs the maternal lipids and carbohydrates toward the fetus, an excellent example of paternal manipulation of maternal physiology and metabolic patriarchy. Further, studies have shown that fathers fed with a high-fat diet reduce the pregnancy success rate because of the reduction of their sperm motility. Excess intake of processed food, highsugar diets, or fructose has consequences on offspring’s cardiovascular and metabolic diseases. Males fed a low protein diet in mice results in glucose intolerance, metabolic and cardiovascular dysfunctions, and altered patterns of bone mineralization in pups. We, therefore, can conclude a robust paternal influence on pregnancy and fetal outcome. Pregnancy was once thought of as an exclusively maternal affair. Increasing research in this arena seems to have smashed that stereotype with paternal influence seems to play a significant role in shaping the birth process. It is high time that Sylvia patriarchal understanding is redefined with the paternal share of responsibility beyond just dominance and an authoritarian role.

Decreasing Intracellular Entropy by Increasing Mitochondrial Efficiency and Reducing ROS Formation-The Effect on the Ageing Process and Age-Related Damage.

A hypothesis is presented to explain how the ageing process might be influenced by optimizing mitochondrial efficiency to reduce intracellular entropy. Research-based quantifications of entropy are scarce. Non-equilibrium metabolic reactions and compartmentalization were found to contribute most to lowering entropy in the cells. Like the cells, mitochondria are thermodynamically open systems exchanging matter and energy with their surroundings-the rest of the cell. Based on the calculations from cancer cells, glycolysis was reported to produce less entropy than mitochondrial oxidative phosphorylation. However, these estimations depended on the CO2 concentration so that at slightly increased CO2, it was oxidative phosphorylation that produced less entropy. Also, the thermodynamic efficiency of mitochondrial respiratory complexes varies depending on the respiratory state and oxidant/antioxidant balance. Therefore, in spite of long-standing theoretical and practical efforts, more measurements, also in isolated mitochondria, with intact and suboptimal respiration, are needed to resolve the issue. Entropy increases in ageing while mitochondrial efficiency of energy conversion, quality control, and turnover mechanisms deteriorate. Optimally functioning mitochondria are necessary to meet energy demands for cellular defence and repair processes to attenuate ageing. The intuitive approach of simply supplying more metabolic fuels (more nutrients) often has the opposite effect, namely a decrease in energy production in the case of nutrient overload. Excessive nutrient intake and obesity accelerate ageing, while calorie restriction without malnutrition can prolong life. Balanced nutrient intake adapted to needs/activity-based high ATP requirement increases mitochondrial respiratory efficiency and leads to multiple alterations in gene expression and metabolic adaptations. Therefore, rather than overfeeding, it is necessary to fine-tune energy production by optimizing mitochondrial function and reducing oxidative stress; the evidence is discussed in this paper.

Epithelial-mesenchymal transition-related signaling pathways in gastric Cancer cells distinctively respond to long-term experimental ketosis.

The interrelationship between cellular metabolism and the epithelial-to-mesenchymal transition (EMT) process has made it an interesting topic to investigate the adjuvant effect of therapeutic diets in the treatment of cancers. However, the findings are controversial. In this study, the effects of glucose limitation along and with the addition of beta-hydroxybutyrate (bHB) were examined on the expression of specific genes and proteins of EMT, Wnt, Hedgehog, and Hippo signaling pathways, and also on cellular behavior of gastric cancer stem-like (MKN-45) and non-stem-like (KATO III) cells. The expression levels of chosen genes and proteins studied in cancer cells gradually adopted a low-glucose condition of one-fourth, along and with the addition of bHB, and compared to the unconditioned control cells. The long-term switching of the metabolic fuels successfully altered the expression profiles and behaviors of both gastric cancer cells. However, the results for some changes were the opposite. Glucose limitation along and with the addition of bHB reduced the CD44+ population in MKN-45 cells. In KATO III cells, glucose restriction increased the CD44+ population. Glucose deprivation alleviated EMT-related signaling pathways in MKN-45 cells but stimulated EMT in KATO III cells. Interestingly, bHB enrichment reduced the beneficial effect of glucose starvation in MKN-45 cells, but also alleviated the adverse effects of glucose restriction in KATO III cells. The findings of this research clearly showed that some controversial results in clinical trials for ketogenic diet in cancer patients stemmed from the different signaling responses of various cells to the metabolic changes in a heterogeneous cancer mass.

Beta hydroxybutyrate induces lung cancer cell death, mitochondrial impairment and oxidative stress in a long term glucose-restricted condition.

Metabolic plasticity gives cancer cells the ability to shift between signaling pathways to facilitate their growth and survival. This study investigates the role of glucose deprivation in the presence and absence of beta-hydroxybutyrate (BHB) in growth, death, oxidative stress and the stemness features of lung cancer cells. A549 cells were exposed to various glucose conditions, both with and without beta-hydroxybutyrate (BHB), to evaluate their effects on apoptosis, mitochondrial membrane potential, reactive oxygen species (ROS) levels using flow cytometry, and the expression of CD133, CD44, SOX-9, and β-Catenin through Quantitative PCR. The activity of superoxide dismutase, glutathione peroxidase, and malondialdehyde was assessed using colorimetric assays. Treatment with therapeutic doses of BHB triggered apoptosis in A549 cells, particularly in cells adapted to glucose deprivation. The elevated ROS levels, combined with reduced levels of SOD and GPx, indicate that oxidative stress contributes to the cell arrest induced by BHB. Notably, BHB treatment under glucose-restricted conditions notably decreased CD133 expression, suggesting a potential inhibition of cell survival through the downregulation of CD133 levels. Additionally, the simultaneous decrease in mitochondrial membrane potential and increase in ROS levels indicate the potential for creating oxidative stress conditions to impede tumor cell growth in such environmental settings. The induced cell death, oxidative stress and mitochondria impairment beside attenuated levels of cancer stem cell markers following BHB administration emphasize on the distinctive role of metabolic plasticity of cancer cells and propose possible therapeutic approaches to control cancer cell growth through metabolic fuels.

Podophyllotoxin via SIRT1/PPAR /NF-κB axis induced cardiac injury in rats based on the toxicological evidence chain (TEC) concept

BackgroundThe study of cardiotoxicity of drugs has become an important part of clinical safety evaluation of drugs. It is commonly known that podophyllotoxin (PPT) and its many derivatives and congeners are broad-spectrum pharmacologically active substances. Clinical cardiotoxicity of PPT and its derivatives has been raised, basic research on the mechanism of cardiotoxicity remains insufficient. PurposeIn present study, our group's innovative concept of toxicological evidence chain (TEC) was applied to reveal the cardiac toxicity mechanism of PPT by targeted metabolomics, TMT-based quantitative proteomics and western blot. MethodsThe injury phenotype evidence (IPE) acquired from the toxicity manifestations, such as weight and behavior observation of Sprague-Dawley rat. The damage to rat hearts were assessed through histopathological examination and myocardial enzymes levels, which were defined as Adverse Outcomes Evidence (AOE). The damage to rat hearts was assessed through histopathological examination and myocardial enzyme levels, which were defined as evidence of adverse outcomes.Overall measurements of targeted metabolomics based on energy metabolism and TMT-based quantitative proteomics were obtained after exposure to PPT to acquire the Toxic Event Evidence (TEE). The mechanism of cardiac toxicity was speculated based on the integrated analysis of targeted metabolomics and TMT-based quantitative proteomics, which was verified by western blot. ResultsThe results indicated that exposure to PPT could result in significant elevation of myocardial enzymes and pathological alterations in rat hearts. In addition, we found that PPT caused disorders in cardiac energy metabolism, characterized by a decrease in energy metabolism fuels. TMT-based quantitative proteomics revealed that the PPAR (Peroxisome proliferators-activated receptor) signaling pathway needs further study. It is worth noting that PPT may suppress the expression of SIRT1, subsequently inhibiting AMPK, decreasing the expression of PGC-1α, PPARα and PPARγ. This results in disorders of glucose oxidation, glycolysis and ketone body metabolism. Additionally, the increase in the expression of p-IKK and p-IκBα, leads to the nuclear translocation of NF-κB p65 from the cytosol, thus triggering inflammation. ConclusionThis study comprehensively evaluated cardiac toxicity of PPT and initially revealed the mechanism of cardiotoxicity,suggesting that PPT induced disorders of energy metabolism and inflammation via SIRT1/PPAR/NF-κB axis, potentially contributing to cardiac injury.

Metabolic Rate Suppression and Maintenance of Flight Muscle Metabolic Capacity during Diapause in Bumble Bee (Bombus impatiens) Queens.

AbstractThe common eastern bumble bee (Bombus impatiens) queens endure cold winter months by entering a diapause state. During this overwintering period, these animals use stored energy reserves while maintaining a low metabolic rate. This study investigates changes in the metabolic rate of bumble bee queens during diapause-like laboratory conditions and the potential reorganization of the flight muscle metabolic properties during this period. We first confirmed the hypometabolic state of queens during diapause in the laboratory, which lowered their resting metabolic rate to less than 5% of normal resting values. Body mass decreased during diapause, body composition changed where carbohydrates decreased initially, and later protein declined, with a similar trend for lipid content. Using cellular respirometry, we determined the capacity of the flight muscle cells of bumble bee queens to use various metabolic fuels and whether this capacity changes during the progression of diapause to favor stored lipid-derived substrates. Queens showed a low capacity to oxidize the amino acid proline, compared with workers, and their capacity to oxidize all metabolic substrates did not change during a 4-mo diapause period in the laboratory. We also show no detectable ability to oxidize fatty acid by flight muscle mitochondria in this species. The metabolic properties of flight muscle tissue were further characterized using metabolic enzyme activity profiles showing little change during diapause, indicating that profound metabolic suppression is induced without major changes in muscle metabolic phenotypes. Overall, B. impatiens queens undergo diapause while maintaining flight muscle capacity under the conditions used.

Abstract 1801: Rewiring of cortical glucose metabolism fuels human brain cancer growth

Abstract The brain avidly consumes glucose to fuel neurophysiology. Cancers of the brain, such as glioblastoma (GBM), lose aspects of normal biology and gain the ability to proliferate and invade healthy tissue. How brain cancers rewire glucose utilization to fuel these processes is poorly understood. Here we perform infusions of 13C-labeled glucose into patients and mice with brain cancer to define the metabolic fates of glucose-derived carbon in tumor and cortex. By combining these measurements with quantitative metabolic flux analysis, we find that human cortex funnels glucose-derived carbons towards physiologic processes including TCA cycle oxidation and neurotransmitter synthesis. In contrast, brain cancers downregulate these physiologic processes, scavenge alternative carbon sources from the environment, and instead use glucose-derived carbons to produce molecules needed for proliferation and invasion. Targeting this metabolic rewiring in mice through dietary modulation selectively alters GBM metabolism and slows tumor growth. Citation Format: Andrew J. Scott, Anjali Mittal, Baharan Meghdadi, Sravya Palavalasa, Abhinav Achreja, Alexandra O'Brien, Ayesha Kothari, Weihua Zhou, Jie Xu, Angelica Lin, Kari Wilder-Romans, Donna M. Edwards, Vijay Tarnal, Nathan Qi, Theodore S. Lawrence, Sriram Venneti, Nathalie Y. Agar, Costas A. Lyssiotis, Wajd N. Al-Holou, Deepak Nagrath, Daniel R. Wahl. Rewiring of cortical glucose metabolism fuels human brain cancer growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1801.

Characteristics of the Digestive Tract of Dogs and Cats.

As for other mammals, the digestive system of dogs (facultative carnivores) and cats (obligate carnivores) includes the mouth, teeth, tongue, pharynx, esophagus, stomach, small intestine, large intestine, and accessory digestive organs (salivary glands, pancreas, liver, and gallbladder). These carnivores have a relatively shorter digestive tract but longer canine teeth, a tighter digitation of molars, and a greater stomach volume than omnivorousmammals such as humans and pigs. Both dogs and cats have no detectable or a very low activity of salivary α-amylase but dogs, unlike cats, possess a relativelyhighactivity of pancreatic α-amylase. Thus, cats select low-starch foods but dogs can consume high-starch diets. In contrast tomany mammals, the vitamin B12 (cobalamin)-binding intrinsic factor for the digestion and absorption of vitamin B12 is produced in: (a) dogs primarily by pancreatic ductal cells and to a lesser extent the gastric mucosa; and (b) cats exclusively by the pancreatic tissue. Amino acids (glutamate, glutamine, and aspartate) are the main metabolic fuels in enterocytes of the foregut. The primary function of the small intestine is to digest and absorb dietary nutrients, and its secondary function is to regulate the entry of dietary nutrients into the blood circulation, separate the external from the internal milieu, and perform immune surveillance. The major function of the large intestine is to ferment undigested food (particularly fiber and protein) and to absorb water, short-chain fatty acids (serving as major metabolic fuels for epithelial cells of the large intestine), as well as vitamins. The fermentation products, water, sloughed cells, digestive secretions, and microbes form feces and then pass into the rectum for excretion via the anal canal. The microflora influences colonic absorption and cell metabolism, as well as feces quality. The digestive tract is essential for the health, survival, growth, and development of dogs and cats.

Arteriovenous Metabolomics to Measure In Vivo Metabolite Exchange in Brown Adipose Tissue.

Brown adipose tissue (BAT) plays a crucial role in regulating metabolic homeostasis through a unique energy expenditure process known as non-shivering thermogenesis. To achieve this, BAT utilizes a diverse menu of circulating nutrients to support its high metabolic demand. Additionally, BAT secretes metabolite-derived bioactive factors that can serve as either metabolic fuels or signaling molecules, facilitating BAT-mediated intratissue and/or intertissue communication. This suggests that BAT actively participates in systemic metabolite exchange, an interesting feature that is beginning to be explored. Here, we introduce a protocol for in vivo mouse-level optimized BAT arteriovenous metabolomics. The protocol focuses on relevant methods for thermogenic stimulations and an arteriovenous blood sampling technique using Sulzer's vein, which selectively drains interscapular BAT-derived venous blood and systemic arterial blood. Next, a gas chromatography-based metabolomics protocol using those blood samples is demonstrated. The use of this technique should expand the understanding of BAT-regulated metabolite exchange at the inter-organ level by measuring the net uptake and release of metabolites by BAT.

Aberrant metabolite trafficking and fuel sensitivity in human pluripotent stem cell-derived islets

Pancreatic islets regulate blood glucose homeostasis through the controlled release of insulin; however, current metabolic models of glucose-sensitive insulin secretion are incomplete. A comprehensive understanding of islet metabolism is integral to studies of endocrine cell development as well as diabetic islet dysfunction. Human pluripotent stem cell-derived islets (SC-islets) are a developmentally relevant model of human islet function that have great potential in providing a cure for type 1 diabetes. Using multiple 13C-labeled metabolic fuels, we demonstrate that SC-islets show numerous divergent patterns of metabolite trafficking in proposed insulin release pathways compared with primary human islets but are still reliant on mitochondrial aerobic metabolism to derive function. Furthermore, reductive tricarboxylic acid cycle activity and glycolytic metabolite cycling occur in SC-islets, suggesting that non-canonical coupling factors are also present. In aggregate, we show that many facets of SC-islet metabolism overlap with those of primary islets, albeit with a retained immature signature.

Uridine as a novel fuel for cancer cells

Cancer cells are known to have an enormous appetite for calorie. This is something they are addicted to sustain their unrestricted growth and rapid proliferation. In order to accomplish this feat, cancer cells has evolved multiple mechanisms, rewiring their metabolic circuitry such that metabolic fuels are preferentially diverted to meet their energy demands. A classic example (Warburg effect) of this is aerobic glycolysis and preferential production of lactate to produce ATP (without relying on mitochondrial oxidative phosphorylation). Further, rapid proliferation of cancer cells, exhausts the nutrient and oxygen supply derived from the existing vasculature, making them hypoxic. In turn triggers the upregulation of pro angiogenic factors from the hypoxic tumor sites( HIF), which in turn re-vascularizes the tumor mass, bringing in metabolic cargo.
 When it comes to cancer metabolism, cancer cells are highly innovative to devise novel mechanisms to bypass metabolic regulations and In a recent article published in Nature Metabolism, Skinner et al. identified an unusual source of glucose in cancer cells. Ribose moiety of uridine can be repurposed to replenish the energy requirements in cancer cells thorough the uridine phosphorylase UPP1/UPP2 mediated cleavage of uridine into its constituents , uracil and ribose-1-phosphate (R1P). R1P is then utilized to convert into fructose-6-P and glyceraldehyde-3-P by the non-oxidative branch of the HMP shunt back to glycolysis and ATP production.
 These findings are novel and intuitive. It means that the cancer cells has the ability to salvage glucose from uridine, when needed. This also indicates that cutting off Uridine supply to cancer cells maybe a mechanism to target cancer cells .

22-OR: High Glucose Metabolism Fuels Cathepsin L Maturation to Promote SARS-CoV-2 Infection in Patients with Diabetes

Patients with diabetes are more likely to develop severe COVID-19 and deaths. However, the underlying mechanism remains poorly understood. Previously, we identified a widely expressed lysosome protease Cathepsin L (CTSL) promotes SARS-CoV-2 infection and may be a promising drug target (PMID: 33774649, 35668062). Here, we show that patients with diabetes have elevated CTSL concentration and activity in patients with or without COVID-19. The CTSL levels are positively correlated with HbA1c in humans. Hyperglycemic clamp study suggests that high glucose increases CTSL activity in healthy individuals. In vitro, we find that high glucose, but not high insulin, level promotes SARS-CoV-2 infection in wildtype (WT) cells. However, these promoting effects are largely reduced in CTSL-knockout (KO) cells. By using lung tissues from healthy, diabetic patients, WT and db/db mice, we find diabetes promotes CTSL maturation. Further, we identify that high glucose level, but not high insulin level, promotes CTSL activity. The matured CTSL levels are significantly increased in diabetic tissues. High glucose promotes CTSL translocation from the endoplasmic reticulum (ER) to lysosome through the ER-Golgi-lysosome axis (Fig.1). Our study reports the biological and potential clinical significance of glucose metabolism in CTSL maturation to promotes SARS-CoV-2 infection in patients with diabetes. Disclosure M.Zhao: None. Q.He: None. J.Yang: None. Funding National Natural Science Foundation of China (81930019)

Platelet glycogenolysis is important for energy production and function

Although the presence of glycogen in platelets was established in the 1960s, its importance to specific functions (i.e., activation, secretion, aggregation, and clot contraction) remains unclear. Patients with glycogen storage disease often present with increased bleeding and glycogen phosphorylase (GP) inhibitors, when used as treatments for diabetes, induce bleeding in preclinical studies suggesting some role for this form of glucose in hemostasis. In the present work, we examined how glycogen mobilization affects platelet function using GP inhibitors (CP316819 and CP91149) and a battery of ex vivo assays. Blocking GP activity increased glycogen levels in resting and thrombin-activated platelets and inhibited platelet secretion and clot contraction, with minimal effects on aggregation. Seahorse energy flux analysis and metabolite supplementation experiments suggested that glycogen is an important metabolic fuel whose role is affected by platelet activation and the availability of external glucose and other metabolic fuels. Our data shed light on the bleeding diathesis in glycogen storage disease patients and offer insights into the potential effects of hyperglycemia on platelets.

Uridine Utilization Drives Pancreatic Cancer in Low-Nutrient Conditions.

Uridine metabolism fuels pancreatic cancer growth and progression under low-glucose conditions.

Targeting immunometabolism during cardiorenal injury: roles of conventional and alternative macrophage metabolic fuels.

Macrophages play critical roles in mediating and resolving tissue injury as well as tissue remodeling during cardiorenal disease. Altered immunometabolism, particularly macrophage metabolism, is a critical underlying mechanism of immune dysfunction and inflammation, particularly in individuals with underlying metabolic abnormalities. In this review, we discuss the critical roles of macrophages in cardiac and renal injury and disease. We also highlight the roles of macrophage metabolism and discuss metabolic abnormalities, such as obesity and diabetes, which may impair normal macrophage metabolism and thus predispose individuals to cardiorenal inflammation and injury. As the roles of macrophage glucose and fatty acid metabolism have been extensively discussed elsewhere, we focus on the roles of alternative fuels, such as lactate and ketones, which play underappreciated roles during cardiac and renal injury and heavily influence macrophage phenotypes.

Blood-Glucose-Powered Metabolic Fuel Cell for Self-Sufficient Bioelectronics.

Currently available bioelectronic devices consume too much power to be continuously operated on rechargeable batteries, and are often powered wirelessly, with attendant issues regarding reliability, convenience, and mobility. Thus, the availability of a robust, self-sufficient, implantable electrical power generator that works under physiological conditions would be transformative for many applications, from driving bioelectronic implants and prostheses to programing cellular behavior and patients' metabolism. Here, capitalizing on a new copper-containing, conductively tuned 3D carbon nanotube composite, an implantable blood-glucose-powered metabolic fuel cell is designed that continuously monitors blood-glucose levels, converts excess glucose into electrical power during hyperglycemia, and produces sufficient energy (0.7mW cm-2 , 0.9V, 50mm glucose) to drive opto- and electro-genetic regulation of vesicular insulin release from engineered beta cells. It is shown that this integration of blood-glucose monitoring with elimination of excessive blood glucose by combined electro-metabolic conversion and insulin-release-mediated cellular consumption enables the metabolic fuel cell to restore blood-glucose homeostasis in an automatic, self-sufficient, and closed-loop manner in an experimental model of type-1 diabetes.

Astrocyte strategies in the energy-efficient brain.

Astrocytes generate ATP through glycolysis and mitochondrion respiration, using glucose, lactate, fatty acids, amino acids, and ketone bodies as metabolic fuels. Astrocytic mitochondria also participate in neuronal redox homeostasis and neurotransmitter recycling. In this essay, we aim to integrate the multifaceted evidence about astrocyte bioenergetics at the cellular and systems levels, with a focus on mitochondrial oxidation. At the cellular level, the use of fatty acid β-oxidation and the existence of molecular switches for the selection of metabolic mode and fuels are examined. At the systems level, we discuss energy audits of astrocytes and how astrocytic Ca2+ signaling might contribute to the higher performance and lower energy consumption of the brain as compared to engineered circuits. We finish by examining the neural-circuit dysregulation and behavior impairment associated with alterations of astrocytic mitochondria. We conclude that astrocytes may contribute to brain energy efficiency by coupling energy, redox, and computational homeostasis in neural circuits.