Acetate Revisited: A Key Biomolecule at the Nexus of Metabolism, Epigenetics and Oncogenesis-Part 1: Acetyl-CoA, Acetogenesis and Acyl-CoA Short-Chain Synthetases

β cell acetate production and release are negligible

BACKGROUND

Studies suggest that short chain fatty acids (SCFAs), which are primarily produced from fermentation of fiber, regulate insulin secretion through free fatty acid receptors 2 and 3 (FFA2 and FFA3). As these are G-protein coupled receptors (GPCRs), they have potential therapeutic value as targets for treating type 2 diabetes (T2D). The exact mechanism by which these receptors regulate insulin secretion and other aspects of pancreatic β cell function is unclear. It has been reported that glucose-dependent release of acetate from pancreatic β cells negatively regulates glucose stimulated insulin secretion. While these data raise the possibility of acetate's potential autocrine action on these receptors, these findings have not been independently confirmed, and multiple concerns exist with this observation, particularly the lack of specificity and precision of the acetate detection methodology used.

METHODS

Using Min6 cells and mouse islets, we assessed acetate and pyruvate production and secretion in response to different glucose concentrations, via liquid chromatography mass spectrometry.

RESULTS

Using Min6 cells and mouse islets, we showed that both intracellular pyruvate and acetate increased with high glucose conditions; however, intracellular acetate level increased only slightly and exclusively in Min6 cells but not in the islets. Further, extracellular acetate levels were not affected by the concentration of glucose in the incubation medium of either Min6 cells or islets.

CONCLUSIONS

Our findings do not substantiate the glucose-dependent release of acetate from pancreatic β cells, and therefore, invalidate the possibility of an autocrine inhibitory effect on glucose stimulated insulin secretion.

Quantifying Protein Acetylation in Diabetic Nephropathy from Formalin-Fixed Paraffin-Embedded Tissue

PURPOSE

Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and a leading cause of chronic kidney disease and end-stage renal disease. One potential mechanism underlying cellular dysfunction contributing to kidney disease is aberrant protein post-translational modifications. Lysine acetylation is associated with cellular metabolic flux and is thought to be altered in patients with diabetes and dysfunctional renal metabolism.

EXPERIMENTAL DESIGN

A novel extraction and LC-MS/MS approach was adapted to quantify sites of lysine acetylation from formalin-fixed paraffin-embedded (FFPE) kidney tissue and from patients with DKD and non-diabetic donors (n = 5 and n = 7, respectively).

RESULTS

Analysis of FFPE tissues identified 840 total proteins, with 225 of those significantly changing in patients with DKD. Acetylomic analysis quantified 289 acetylated peptides, with 69 of those significantly changing. Pathways impacted in DKD patients revealed numerous metabolic pathways, specifically mitochondrial function, oxidative phosphorylation, and sirtuin signaling. Differential protein acetylation in DKD patients impacted sirtuin signaling, valine, leucine, and isoleucine degradation, lactate metabolism, oxidative phosphorylation, and ketogenesis.

CONCLUSIONS AND CLINICAL RELEVANCE

A quantitative acetylomics platform was developed for protein biomarker discovery in formalin-fixed and paraffin-embedded biopsies of kidney transplant patients suffering from DKD.

Uncovering the impact of alcohol on internal organs and reproductive health: Exploring TLR4/NF-kB and CYP2E1/ROS/Nrf2 pathways

This review delves into the detrimental impact of alcohol consumption on internal organs and reproductive health, elucidating the underlying mechanisms involving the Toll-like receptor 4 (TLR4)/Nuclear factor kappa light chain enhancer of activated B cells (NF-kB) pathway and the Cytochrome P450 2E1 (CYP2E1)/reactive oxygen species (ROS)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathways. The TLR4/NF-kB pathway, crucial for inflammatory and immune responses, triggers the production of pro-inflammatory agents and type-1 interferon, disrupting the balance between inflammatory and antioxidant responses when tissues are chronically exposed to alcohol. Alcohol-induced dysbiosis in gut microbes heightens gut wall permeability to pathogen-associated molecular patterns (PAMPs), leading to liver cell infection and subsequent inflammation. Concurrently, CYP2E1-mediated alcohol metabolism generates ROS, causing oxidative stress and damaging cells, lipids, proteins, and deoxyribonucleic acid (DNA). To counteract this inflammatory imbalance, Nrf2 regulates gene expression, inhibiting inflammatory progression and promoting antioxidant responses. Excessive alcohol intake results in elevated liver enzymes (ADH, CYP2E1, and catalase), ROS, NADH, acetaldehyde, and acetate, leading to damage in vital organs such as the heart, brain, and lungs. Moreover, alcohol negatively affects reproductive health by inhibiting the hypothalamic-pituitary-gonadal axis, causing infertility in both men and women. These findings underscore the profound health concerns associated with alcohol-induced damage, emphasizing the need for public awareness regarding the intricate interplay between immune responses and the multi-organ impacts of alcohol consumption.

Characterization of Urinary N-Acetyltaurine as a Biomarker of Hyperacetatemia in Mice

Acetate is an important metabolite in metabolic fluxes. Its presence in biological entities originates from both exogenous inputs and endogenous metabolism. Because the change in blood acetate level has been associated with both beneficial and adverse health outcomes, blood acetate analysis has been used to monitor the systemic status of acetate turnover. The present study examined the use of urinary N-acetyltaurine (NAT) as a marker to reflect the hyperacetatemic status of mice from exogenous inputs and endogenous metabolism, including triacetin dosing, ethanol dosing, and streptozotocin-induced diabetes. The results showed that triacetin dosing increased serum acetate and urinary NAT but not other N-acetylated amino acids in urine. The co-occurrences of increased serum acetate and elevated urinary NAT were also observed in both ethanol dosing and streptozotocin-induced diabetes. Furthermore, the renal cortex was determined as an active site for NAT synthesis. Overall, urinary NAT behaved as an effective marker of hyperacetatemia in three experimental mouse models, warranting further investigation into its application in humans.

ACSS2 enables melanoma cell survival and tumor metastasis by negatively regulating the Hippo pathway

Introduction

Acetyl-CoA synthetase 2 (ACSS2), one of the enzymes that catalyze the conversion of acetate to acetyl-CoA, has been proved to be an oncogene in various cancers. However, the function of ACSS2 is still largely a black box in melanoma.

Methods

The ACSS2 expression was detected in melanoma cells and melanocytes at both protein and mRNA levels. Cell viability, apoptosis, migration and invasion were investigated after ACSS2 knockdown. RNA sequencing (RNA-Seq) technology was employed to identify differentially expressed genes caused by ACSS2 knockdown, which were then verified by immunoblotting analysis. Animal experiments were further performed to investigate the influence of ACSS2 on tumor growth and metastasis in vivo.

Results

Firstly, we found that ACSS2 was upregulated in most melanoma cell lines compared with melanocytes. In addition, ACSS2 knockdown dramatically suppressed melanoma cell migration and invasion, whereas promoted cell apoptosis in response to endoplasmic reticulum (ER) stress. Furthermore, tumor growth and metastasis were dramatically suppressed by ACSS2 knockdown in vivo. RNA-Seq suggested that the Hippo pathway was activated by ACSS2 knockdown, which was forwardly confirmed by Western blotting and rescue experiments. Taken together, we demonstrated that ACSS2 enables melanoma cell survival and tumor metastasis via the regulation of the Hippo pathway.

Discussion

In summary, this study demonstrated that ACSS2 may promote the growth and metastasis of melanoma by negatively regulating the Hippo pathway. Targeting ACSS2 may be a promising target for melanoma treatment.

Citric Acid: A Nexus Between Cellular Mechanisms and Biomaterial Innovations

Citrate-based biodegradable polymers have emerged as a distinctive biomaterial platform with tremendous potential for diverse medical applications. By harnessing their versatile chemistry, these polymers exhibit a wide range of material and bioactive properties, enabling them to regulate cell metabolism and stem cell differentiation through energy metabolism, metabonegenesis, angiogenesis, and immunomodulation. Moreover, the recent US Food and Drug Administration (FDA) clearance of the biodegradable poly(octamethylene citrate) (POC)/hydroxyapatite-based orthopedic fixation devices represents a translational research milestone for biomaterial science. POC joins a short list of biodegradable synthetic polymers that have ever been authorized by the FDA for use in humans. The clinical success of POC has sparked enthusiasm and accelerated the development of next-generation citrate-based biomaterials. This review presents a comprehensive, forward-thinking discussion on the pivotal role of citrate chemistry and metabolism in various tissue regeneration and on the development of functional citrate-based metabotissugenic biomaterials for regenerative engineering applications.

Mitochondrial ACSS1-K635 acetylation knock-in mice exhibit altered metabolism, cell senescence, and nonalcoholic fatty liver disease

Acetyl-CoA synthetase short-chain family member 1 (ACSS1) uses acetate to generate mitochondrial acetyl-CoA and is regulated by deacetylation by sirtuin 3. We generated an ACSS1-acetylation (Ac) mimic mouse, where lysine-635 was mutated to glutamine (K635Q). Male Acss1K635Q/K635Q mice were smaller with higher metabolic rate and blood acetate and decreased liver/serum ATP and lactate levels. After a 48-hour fast, Acss1K635Q/K635Q mice presented hypothermia and liver aberrations, including enlargement, discoloration, lipid droplet accumulation, and microsteatosis, consistent with nonalcoholic fatty liver disease (NAFLD). RNA sequencing analysis suggested dysregulation of fatty acid metabolism, cellular senescence, and hepatic steatosis networks, consistent with NAFLD. Fasted Acss1K635Q/K635Q mouse livers showed increased fatty acid synthase (FASN) and stearoyl-CoA desaturase 1 (SCD1), both associated with NAFLD, and increased carbohydrate response element-binding protein binding to Fasn and Scd1 enhancer regions. Last, liver lipidomics showed elevated ceramide, lysophosphatidylethanolamine, and lysophosphatidylcholine, all associated with NAFLD. Thus, we propose that ACSS1-K635-Ac dysregulation leads to aberrant lipid metabolism, cellular senescence, and NAFLD.

Cellular and molecular mechanisms of aspartoacylase and its role in Canavan disease

Canavan disease is an autosomal recessive and lethal neurological disorder, characterized by the spongy degeneration of the white matter in the brain. The disease is caused by a deficiency of the cytosolic aspartoacylase (ASPA) enzyme, which catalyzes the hydrolysis of N-acetyl-aspartate (NAA), an abundant brain metabolite, into aspartate and acetate. On the physiological level, the mechanism of pathogenicity remains somewhat obscure, with multiple, not mutually exclusive, suggested hypotheses. At the molecular level, recent studies have shown that most disease linked ASPA gene variants lead to a structural destabilization and subsequent proteasomal degradation of the ASPA protein variants, and accordingly Canavan disease should in general be considered a protein misfolding disorder. Here, we comprehensively summarize the molecular and cell biology of ASPA, with a particular focus on disease-linked gene variants and the pathophysiology of Canavan disease. We highlight the importance of high-throughput technologies and computational prediction tools for making genotype-phenotype predictions as we await the results of ongoing trials with gene therapy for Canavan disease.

Twelve-hour normothermic liver perfusion in a rat model: characterization of the changes in the ex-situ bio-molecular phenotype and metabolism

The partial understanding of the biological events that occur during normothermic machine perfusion (NMP) and particularly during prolonged perfusion might hinder its deployment in clinical transplantation. The aim of our study was to implement a rat model of prolonged NMP to characterize the bio-molecular phenotype and metabolism of the perfused organs. Livers (n = 5/group) were procured and underwent 4 h (NMP4h) or 12 h (NMP12h) NMP, respectively, using a perfusion fluid supplemented with an acellular oxygen carrier. Organs that were not exposed to any procedure served as controls (Native). All perfused organs met clinically derived viability criteria at the end of NMP. Factors related to stress-response and survival were increased after prolonged perfusion. No signs of oxidative damage were detected in both NMP groups. Evaluation of metabolite profiles showed preserved mitochondrial function, activation of Cori cycle, induction of lipolysis, acetogenesis and ketogenesis in livers exposed to 12 h-NMP. Increased concentrations of metabolites involved in glycogen synthesis, glucuronidation, bile acid conjugation, and antioxidant response were likewise observed. In conclusion, our NMP12h model was able to sustain liver viability and function, thereby deeply changing cell homeostasis to maintain a newly developed equilibrium. Our findings provide valuable information for the implementation of optimized protocols for prolonged NMP.

Lipid Metabolism as a Potential Target of Liver Cancer

Hepatocellular carcinoma (HCC) stands as a severe malignant tumor with a profound impact on overall health, often accompanied by an unfavorable prognosis. Despite some advancements in the diagnosis and treatment of this disease, improving the prognosis of HCC remains a formidable challenge. It is noteworthy that lipid metabolism plays a pivotal role in the onset, development, and progression of tumor cells. Existing research indicates the potential application of targeting lipid metabolism in the treatment of HCC. This review aims to thoroughly explore the alterations in lipid metabolism in HCC, offering a detailed account of the potential advantages associated with innovative therapeutic strategies targeting lipid metabolism. Targeting lipid metabolism holds promise for potentially enhancing the prognosis of HCC.

Histone Acyl Code in Precision Oncology: Mechanistic Insights from Dietary and Metabolic Factors

Cancer etiology involves complex interactions between genetic and non-genetic factors, with epigenetic mechanisms serving as key regulators at multiple stages of pathogenesis. Poor dietary habits contribute to cancer predisposition by impacting DNA methylation patterns, non-coding RNA expression, and histone epigenetic landscapes. Histone post-translational modifications (PTMs), including acyl marks, act as a molecular code and play a crucial role in translating changes in cellular metabolism into enduring patterns of gene expression. As cancer cells undergo metabolic reprogramming to support rapid growth and proliferation, nuanced roles have emerged for dietary- and metabolism-derived histone acylation changes in cancer progression. Specific types and mechanisms of histone acylation, beyond the standard acetylation marks, shed light on how dietary metabolites reshape the gut microbiome, influencing the dynamics of histone acyl repertoires. Given the reversible nature of histone PTMs, the corresponding acyl readers, writers, and erasers are discussed in this review in the context of cancer prevention and treatment. The evolving 'acyl code' provides for improved biomarker assessment and clinical validation in cancer diagnosis and prognosis.

Reprogramming Short-Chain Fatty Acid Metabolism Mitigates Tissue Damage for Streptococcus pyogenes Necrotizing Skin Infection

Disease Tolerance (DT) is a host response to infection that limits collateral damage to host tissues while having a neutral effect on pathogen fitness. Previously, we found that the pathogenic lactic acid bacterium Streptococcus pyogenes manipulates DT using its aerobic mixed-acid fermentation (ARMAF) pathway via the enzyme pyruvate dehydrogenase (PDH) to alter expression of the immunosuppressive cytokine IL-10. However, the microbe-derived molecules that mediate communication with the host's DT pathways remain elusive. Here, we show that ARMAF inhibits accumulation of IL-10-producing inflammatory cells including neutrophils and macrophages, leading to delayed bacterial clearance and wound healing. Expression of IL-10 is inhibited through streptococcal production of the short chain fermentation end-products acetate and formate, via manipulation of host acetyl-CoA metabolism, altering non-histone regulatory lysine acetylation. A bacterial-specific PDH inhibitor reduced tissue damage during murine infection, suggesting that reprogramming carbon flow provides a novel therapeutic strategy to mitigate tissue damage during infection.

Bridging the Gap from Enterotypes to Personalized Dietary Recommendations: A Metabolomics Perspective on Microbiome Research

Advances in high-throughput DNA sequencing have propelled research into the human microbiome and its link to metabolic health. We explore microbiome analysis methods, specifically emphasizing metabolomics, how dietary choices impact the production of microbial metabolites, providing an overview of studies examining the connection between enterotypes and diet, and thus, improvement of personalized dietary recommendations. Acetate, propionate, and butyrate constitute more than 95% of the collective pool of short-chain fatty acids. Conflicting data on acetate's effects may result from its dynamic signaling, which can vary depending on physiological conditions and metabolic phenotypes. Human studies suggest that propionate has overall anti-obesity effects due to its well-documented chemistry, cellular signaling mechanisms, and various clinical benefits. Butyrate, similar to propionate, has the ability to reduce obesity by stimulating the release of appetite-suppressing hormones and promoting the synthesis of leptin. Tryptophan affects systemic hormone secretion, with indole stimulating the release of GLP-1, which impacts insulin secretion, appetite suppression, and gastric emptying. Bile acids, synthesized from cholesterol in the liver and subsequently modified by gut bacteria, play an essential role in the digestion and absorption of dietary fats and fat-soluble vitamins, but they also interact directly with intestinal microbiota and their metabolites. One study using statistical methods identified primarily two groupings of enterotypes Bacteroides and Ruminococcus. The Prevotella-dominated enterotype, P-type, in humans correlates with vegetarians, high-fiber and carbohydrate-rich diets, and traditional diets. Conversely, individuals who consume diets rich in animal fats and proteins, typical in Western-style diets, often exhibit the Bacteroides-dominated, B-type, enterotype. The P-type showcases efficient hydrolytic enzymes for plant fiber degradation but has limited lipid and protein fermentation capacity. Conversely, the B-type features specialized enzymes tailored for the degradation of animal-derived carbohydrates and proteins, showcasing an enhanced saccharolytic and proteolytic potential. Generally, models excel at predictions but often struggle to fully elucidate why certain substances yield varied responses. These studies provide valuable insights into the potential for personalized dietary recommendations based on enterotypes.

Acetate and succinate benefit host muscle energetics as exercise-associated post-biotics

Recently, the gut microbiome has emerged as a potent modulator of exercise-induced systemic adaptation and appears to be crucial for mediating some of the benefits of exercise. This study builds upon previous evidence establishing a gut microbiome-skeletal muscle axis, identifying exercise-induced changes in microbiome composition. Metagenomics sequencing of fecal samples from non-exercise-trained controls or exercise-trained mice was conducted. Biodiversity indices indicated exercise training did not change alpha diversity. However, there were notable differences in beta-diversity between trained and untrained microbiomes. Exercise significantly increased the level of the bacterial species Muribaculaceae bacterium DSM 103720. Computation simulation of bacterial growth was used to predict metabolites that accumulate under in silico culture of exercise-responsive bacteria. We identified acetate and succinate as potential gut microbial metabolites that are produced by Muribaculaceae bacterium, which were then administered to mice during a period of mechanical overload-induced muscle hypertrophy. Although no differences were observed for the overall muscle growth response to succinate or acetate administration during the first 5 days of mechanical overload-induced hypertrophy, acetate and succinate increased skeletal muscle mitochondrial respiration. When given as post-biotics, succinate or acetate treatment may improve oxidative metabolism during muscle hypertrophy.

Effect of acetate supplementation on traumatic stress-induced behavioral impairments in male rats

Gut microbiota and their metabolites have emerged as key players in the pathogenesis of neuropsychiatric disorders. Recently, we demonstrated that animals susceptible to Single Prolonged Stress (SPS) have an overall pro-inflammatory gut microbiota and significantly lower cecal acetate levels than SPS-resilient rats, which correlated inversely with the anxiety index. Here, we investigated whether the microbial metabolite, acetate, could ameliorate SPS-triggered impairments. Male rats were randomly divided into unstressed controls or groups exposed to SPS. The groups received continued oral supplementation of either 150 mM of sodium acetate or 150 mM of sodium chloride-matched water. Two weeks after SPS, a battery of behavioral tests was performed, and the animals were euthanized the following day. While not affecting the unstressed controls, acetate supplementation reduced the impact of SPS on body weight gain and ameliorated SPS-induced anxiety-like behavior and the impairments in social interaction, but not depressive-like behavior. These changes were accompanied by several beneficial effects of acetate supplementation. Acetate alleviated the stress response by reducing urinary epinephrine levels, induced epigenetic modification by decreasing histone deacetylase (HDAC2) gene expression, inhibited neuroinflammation by reducing the density of Iba1+ cells and the gene expression of IL-1ß in the hippocampus, and increased serum β-hydroxybutyrate levels. The findings reveal a causal relationship between oral acetate treatment and mitigation of several SPS-induced behavioral impairments. Mechanistically, it impacted neuronal and metabolic pathways including changes in stress response, epigenetic modifications, neuroinflammation and showed novel link to ketone body production. The study demonstrates the preventive-therapeutic potential of acetate supplementation to alleviate adverse responses to traumatic stress.

Activation of acetyl-CoA synthetase 2 mediates kidney injury in diabetic nephropathy

Albuminuria and podocyte injury are the key cellular events in the progression of diabetic nephropathy (DN). Acetyl-CoA synthetase 2 (ACSS2) is a nucleocytosolic enzyme responsible for the regulation of metabolic homeostasis in mammalian cells. This study aimed to investigate the possible roles of ACSS2 in kidney injury in DN. We constructed an ACSS2-deleted mouse model to investigate the role of ACSS2 in podocyte dysfunction and kidney injury in diabetic mouse models. In vitro, podocytes were chosen and transfected with ACSS2 siRNA and ACSS2 inhibitor and treated with high glucose. We found that ACSS2 expression was significantly elevated in the podocytes of patients with DN and diabetic mice. ACSS2 upregulation promoted phenotype transformation and inflammatory cytokine expression while inhibiting podocytes' autophagy. Conversely, ACSS2 inhibition improved autophagy and alleviated podocyte injury. Furthermore, ACSS2 epigenetically activated raptor expression by histone H3K9 acetylation, promoting activation of the mammalian target of rapamycin complex 1 (mTORC1) pathway. Pharmacological inhibition or genetic depletion of ACSS2 in the streptozotocin-induced diabetic mouse model greatly ameliorated kidney injury and podocyte dysfunction. To conclude, ACSS2 activation promoted podocyte injury in DN by raptor/mTORC1-mediated autophagy inhibition.

The Physiological and Pathological Role of Acyl-CoA Oxidation

Fatty acid metabolism, including β-oxidation (βOX), plays an important role in human physiology and pathology. βOX is an essential process in the energy metabolism of most human cells. Moreover, βOX is also the source of acetyl-CoA, the substrate for (a) ketone bodies synthesis, (b) cholesterol synthesis, (c) phase II detoxication, (d) protein acetylation, and (d) the synthesis of many other compounds, including N-acetylglutamate-an important regulator of urea synthesis. This review describes the current knowledge on the importance of the mitochondrial and peroxisomal βOX in various organs, including the liver, heart, kidney, lung, gastrointestinal tract, peripheral white blood cells, and other cells. In addition, the diseases associated with a disturbance of fatty acid oxidation (FAO) in the liver, heart, kidney, lung, alimentary tract, and other organs or cells are presented. Special attention was paid to abnormalities of FAO in cancer cells and the diseases caused by mutations in gene-encoding enzymes involved in FAO. Finally, issues related to α- and ω- fatty acid oxidation are discussed.

Epigenetic meets metabolism: novel vulnerabilities to fight cancer

Histones undergo a plethora of post-translational modifications (PTMs) that regulate nucleosome and chromatin dynamics and thus dictate cell fate. Several evidences suggest that the accumulation of epigenetic alterations is one of the key driving forces triggering aberrant cellular proliferation, invasion, metastasis and chemoresistance pathways. Recently a novel class of histone "non-enzymatic covalent modifications" (NECMs), correlating epigenome landscape and metabolic rewiring, have been described. These modifications are tightly related to cell metabolic fitness and are able to impair chromatin architecture. During metabolic reprogramming, the high metabolic flux induces the accumulation of metabolic intermediate and/or by-products able to react with histone tails altering epigenome homeostasis. The accumulation of histone NECMs is a damaging condition that cancer cells counteracts by overexpressing peculiar "eraser" enzymes capable of removing these modifications preserving histones architecture. In this review we explored the well-established NECMs, emphasizing the role of their corresponding eraser enzymes. Additionally, we provide a parterre of drugs aiming to target those eraser enzymes with the intent to propose novel routes of personalized medicine based on the identification of epi-biomarkers which might be selectively targeted for therapy. Video Abstract.

Effect of high-starch or high-fibre diets on the energy metabolism and physical performance of horses during an 8-week training period

Large amounts of high-starch concentrates are traditionally fed to horses in training. However, this has been associated with digestive or muscle diseases and behavioural modifications. In parallel, it has been demonstrated that horses fed high-fibre, low-starch diets achieve the same performance over an exercise test as the ones fed high-starch diets. However, whether the same performance level can be maintained over a longer training cycle is still being determined. This study aimed to compare the evolution in physical performance and cardiorespiratory responses of two groups of French Trotters fed either a control high-starch (15.0 g dry matter hay/kg body mass/day + 6.6 g dry matter oats/kg body mass/day) or a high-fibre diet (75% of oats replaced by dehydrated alfalfa) over an 8-week training period. The horses that entered the trial were untrained for ≥4 months and previously fed hay only. Track training with speed monitoring included interval training sessions and 2400 m performance tests from week 1 to week 8 (W8). Before (week 0, W0) and after (week 9, W9) the training period, horses performed an incremental continuous exercise test during which cardiorespiratory parameters were measured. Both groups progressed to the same extent regarding physical performance measured during interval training sessions (acceleration: 0.16 m.s-2 at W0 and 0.40 m.s-2 at W8; p < 0.0001), the 2400 m performance test (average speed: 8.88 m.s-1 at W0 and 10.55 m.s-1 at W8; p < 0.0001), and the incremental continuous exercise test (speed during the fastest stage: 9.57 m.s-1 at W0 and 10.53 m.s-1 at W9; p = 0.030). Although oxygen consumption increased with training (p = 0.071), it was not influenced by the diet. On the contrary, carbon dioxide production increased in the high-starch group only (high-starch group: 84.0 vs. high-fibre group: 77.7 mL.kg-1.min-1 at W9; p = 0.031). The results illustrate that horses in both groups progressed similarly but did not use the same metabolic pathways during exercise. This hypothesis is supported by carbohydrate oxidation, which tended to increase in the high-starch group at W9 but decreased in the high-fibre group (p = 0.061). In conclusion, the substitution of high-starch by high-fibre diets enabled similar performance over an 8-week training period and altered energy metabolism in a way that could be beneficial during high-intensity exercise.

Sodium Butyrate as Key Regulator of Mitochondrial Function and Barrier Integrity of Human Glomerular Endothelial Cells

The gut microbiota has emerged as an important modulator of cardiovascular and renal homeostasis. The composition of gut microbiota in patients suffering from chronic kidney disease (CKD) is altered, where a lower number of bacteria producing short chain fatty acids (SCFAs) is observed. It is known that SCFAs, such as butyrate and acetate, have protective effects against cardiovascular diseases and CKD but their mechanisms of action remain largely unexplored. In the present study, we investigated the effect of butyrate and acetate on glomerular endothelial cells. Human glomerular microvascular endothelial cells (hgMVECs) were cultured and exposed to butyrate and acetate and their effects on cellular proliferation, mitochondrial mass and metabolism, as well as monolayer integrity were studied. While acetate did not show any effects on hgMVECs, our results revealed that butyrate reduces the proliferation of hgMVECs, strengthens the endothelial barrier through increased expression of VE-cadherin and Claudin-5 and promotes mitochondrial biogenesis. Moreover, butyrate reduces the increase in oxygen consumption induced by lipopolysaccharides (LPS), revealing a protective effect of butyrate against the detrimental effects of LPS. Taken together, our data show that butyrate is a key player in endothelial integrity and metabolic homeostasis.

Inhibition of ACSS2 attenuates alcoholic liver steatosis via epigenetically regulating de novo lipogenesis

BACKGROUND AND AIMS

Steatosis is the early pathological change in alcohol-associated liver disease. However, its precise mechanism is still unclear. The present study is aimed to explore the role and mechanism of acetyl-CoA synthetase 2 (ACSS2) in acute alcohol-induced lipogenesis.

METHODS

The increase in ACSS2 nuclear import and histone H3 acetylation were observed in mice after intraperitoneally injected with 2 g/kg ethanol or oral administration of 5 g/kg ethanol and also validated in hepatocytes stimulated with ethanol or acetate. The role of ACSS2 was further explored in liver-specific ACSS2 knockdown mice fed with ethanol-containing diet.

RESULTS

Alcohol challenge induced hepatic lipid deposition and upregulated lipogenic genes in mice. It also promoted ACSS2 nuclear import and increased histone H3 acetylation. In hepatocytes, ethanol induced similar phenomena whereas ACSS2 knockdown blocked histone acetylation and lipogenic gene induction. P300/CBP associated factor (PCAF), but not general control nonderepressible 5, CREB-binding protein (CBP) and p300, facilitated H3K9 acetylation responding to ethanol challenge. CUT&RUN assay showed the enrichment of acetylated histone H3K9 surrounding Fasn and Acaca promoters. These results indicated that ethanol metabolism promoted ACSS2 nuclear import to support lipogenesis via H3K9 acetylation. In alcohol-feeding mice, liver-specific ACSS2 knockdown blocked the interaction between PCAF and H3K9 and suppressed lipogenic gene induction in the liver, demonstrating the critical role of ACSS2 in lipogenesis.

CONCLUSIONS

Our study demonstrated that alcohol metabolism generated acetyl-CoA in the nucleus dependently on nuclear ACSS2, contributing to epigenetic regulation of lipogenesis in hepatic steatosis. Targeting ACSS2 may be a potential therapeutical strategy for acute alcoholic liver steatosis.

The Roles of Coenzyme A Binding Pocket Residues in Short and Medium Chain Acyl-CoA Synthetases

Short- and medium-chain acyl-CoA synthetases catalyze similar two-step reactions in which acyl substrate and ATP bind to form an enzyme-bound acyl-adenylate, then CoA binds for formation of the acyl-CoA product. We investigated the roles of active site residues in CoA binding in acetyl-CoA synthetase (Acs) and a medium-chain acyl-CoA synthetase (Macs) that uses 2-methylbutyryl-CoA. Three highly conserved residues, Arg193, Arg528, and Arg586 of Methanothermobacter thermautotrophicus Acs (AcsMt), are predicted to form important interactions with the 5'- and 3'-phosphate groups of CoA. Kinetic characterization of AcsMt variants altered at each of these positions indicates these Arg residues play a critical role in CoA binding and catalysis. The predicted CoA binding site of Methanosarcina acetivorans Macs (MacsMa) is structurally more closely related to that of 4-chlorobenzoate:coenzyme A ligase (CBAL) than Acs. Alteration of MacsMa residues Tyr460, Arg490, Tyr525, and Tyr527, which correspond to CoA binding pocket residues in CBAL, strongly affected CoA binding and catalysis without substantially affecting acyl-adenylate formation. Both enzymes discriminate between 3'-dephospho-CoA and CoA, indicating interaction between the enzyme and the 3'-phosphate group is important. Alteration of MacsMa residues Lys461 and Lys519, located at positions equivalent to AcsMt Arg528 and Arg586, respectively, had only a moderate effect on CoA binding and catalysis. Overall, our results indicate the active site architecture in AcsMt and MacsMa differs even though these enzymes catalyze mechanistically similar reactions. The significance of this study is that we have delineated the active site architecture with respect to CoA binding and catalysis in this important enzyme superfamily.

ATP-citrate lyase controls endothelial gluco-lipogenic metabolism and vascular inflammation in sepsis-associated organ injury

Sepsis involves endothelial cell (EC) dysfunction, which contributes to multiple organ failure. To improve therapeutic prospects, elucidating molecular mechanisms of vascular dysfunction is of the essence. ATP-citrate lyase (ACLY) directs glucose metabolic fluxes to de novo lipogenesis by generating acetyl-Co-enzyme A (acetyl-CoA), which facilitates transcriptional priming via protein acetylation. It is well illustrated that ACLY participates in promoting cancer metastasis and fatty liver diseases. Its biological functions in ECs during sepsis remain unclear. We found that plasma levels of ACLY were increased in septic patients and were positively correlated with interleukin (IL)-6, soluble E-selectin (sE-selectin), soluble vascular cell adhesion molecule 1 (sVCAM-1), and lactate levels. ACLY inhibition significantly ameliorated lipopolysaccharide challenge-induced EC proinflammatory response in vitro and organ injury in vivo. The metabolomic analysis revealed that ACLY blockade fostered ECs a quiescent status by reducing the levels of glycolytic and lipogenic metabolites. Mechanistically, ACLY promoted forkhead box O1 (FoxO1) and histone H3 acetylation, thereby increasing the transcription of c-Myc (MYC) to facilitate the expression of proinflammatory and gluco-lipogenic genes. Our findings revealed that ACLY promoted EC gluco-lipogenic metabolism and proinflammatory response through acetylation-mediated MYC transcription, suggesting ACLY as the potential therapeutic target for treating sepsis-associated EC dysfunction and organ injury.

Urinary Metabolomic Profile of Youth at Risk of Chronic Kidney Disease in Nicaragua

Key Points

Urinary concentrations of glycine, a molecule associated with thermoregulation, were elevated among youth from a high-risk region for chronic kidney disease of non-traditional etiology (CKDnt). Urinary concentrations of pyruvate, citric acid, and inosine were lower among youth at higher risk of CKDnt, suggesting renal stress. Metabolomic analyses may shed light on early disease processes or profiles or risk in the context of CKDnt.

Background

CKD of a nontraditional etiology (CKDnt) is responsible for high mortality in Central America, although its causes remain unclear. Evidence of kidney dysfunction has been observed among youth, suggesting that early kidney damage contributing to CKDnt may initiate in childhood.

Methods

Urine specimens of young Nicaraguan participants 12–23 years without CKDnt (n =136) were analyzed by proton nuclear magnetic resonance spectroscopy for 50 metabolites associated with kidney dysfunction. Urinary metabolite levels were compared by, regional CKDnt prevalence, sex, age, and family history of CKDnt using supervised statistical methods and pathway analysis in MetaboAnalyst. Magnitude of associations and changes over time were assessed through multivariable linear regression.

Results

In adjusted analyses, glycine concentrations were higher among youth from high-risk regions (β =0.82, [95% confidence interval, 0.16 to 1.85]; P = 0.01). Pyruvate concentrations were lower among youth with low eGFR (β = −0.36 [95% confidence interval, −0.57 to −0.04]; P = 0.03), and concentrations of other citric acid cycle metabolites differed by key risk factors. Over four years, participants with low eGFR experienced greater declines in 1-methylnicotinamide and 2-oxoglutarate and greater increases in citrate and guanidinoacetate concentrations.

Conclusion

Urinary concentration of glycine, a molecule associated with thermoregulation and kidney function preservation, was higher among youth in high-risk CKDnt regions, suggestive of greater heat exposure or renal stress. Lower pyruvate concentrations were associated with low eGFR, and citric acid cycle metabolites, such as pyruvate, likely relate to mitochondrial respiration rates in the kidneys. Participants with low eGFR experienced longitudinal declines in concentrations of 1-methylnicotinamide, an anti-inflammatory metabolite associated with anti-fibrosis in tubule cells. These findings merit further consideration in research on the origins of CKDnt.

Gut microbial metabolites and its impact on human health

One of the primary methods by which the gut microbiome interacts with its host is through the interactions that occur through the production of the metabolites produced, either directly, or indirectly, through microbial metabolism. Decades of research has demonstrated that these metabolic products play a vital role in human health, either for its benefit or detriment. This review article highlights the main metabolites produced by the interactions between diet and the gut microbiome, bile acids and the gut microbiome, and products produced by the gut microbiome alone. Additionally, this article reviews the literature on the effects that these metabolites play on human health.

High-Fat Diet Promotes Adipogenesis in Offspring Female Rats Induced by Perinatal Exposure to 4-Nonylphenol

Background

Both high-fat diet (HFD) and 4-nonylphenol (4-NP) could affect fat formation in adipose tissue individually. We investigated whether HFD promote abnormal adipose tissue formation caused by early exposure to 4-NP in life and preliminarily explore the possible mechanisms involved.

Methods

The first-generation rats were treated with HFD on postnatal day after pregnant rats exposure to 5 ug/kg/day 4-NP. Then, the second generation rats started to only receive normal diet without 4-NP or HFD. We analyzed organ coefficient and histopathology of fat tissues, biochemical index, and gene level involved in lipid metabolism in female offspring rats.

Results

HFD and 4-NP interaction synergistically increased birth weight, body weight, and organ coefficients of adipose tissue in offspring female rats. HFD accelerately aggravated abnormal lipid metabolism and increased the adipocyte mean areas around the uterus of the offspring female rats induced by prenatal exposure to 4-NP. HFD also facilitate the regulation of gene expression involved lipid metabolism in offspring female rats induced by perinatal exposure to 4-NP, even passed on to the second generation of female rats. Moreover, HFD and 4-NP interaction synergistically declined the gene and protein expression of estrogen receptor (ER) in the adipose tissue of second-generation female rats.

Conclusion

HFD and 4-NP synergistically regulate the expression of lipid metabolism genes in adipose tissue of F2 female rats and promote adipose tissue generation, leading to obesity in offspring rats, which is closely related to low expression of ER. Therefore, ER genes and proteins may be involved in the synergistic effect of HFD and 4-NP.

Acss2/HIF-2 signaling facilitates colon cancer growth and metastasis

The microenvironment of solid tumors is characterized by oxygen and glucose deprivation. Acss2/HIF-2 signaling coordinates essential genetic regulators including acetate-dependent acetyl CoA synthetase 2 (Acss2), Creb binding protein (Cbp), Sirtuin 1 (Sirt1), and Hypoxia Inducible Factor 2α (HIF-2α). We previously shown in mice that exogenous acetate augments growth and metastasis of flank tumors derived from fibrosarcoma-derived HT1080 cells in an Acss2/HIF-2 dependent manner. Colonic epithelial cells are exposed to the highest acetate levels in the body. We reasoned that colon cancer cells, like fibrosarcoma cells, may respond to acetate in a pro-growth manner. In this study, we examine the role of Acss2/HIF-2 signaling in colon cancer. We find that Acss2/HIF-2 signaling is activated by oxygen or glucose deprivation in two human colon cancer-derived cell lines, HCT116 and HT29, and is crucial for colony formation, migration, and invasion in cell culture studies. Flank tumors derived from HCT116 and HT29 cells exhibit augmented growth in mice when supplemented with exogenous acetate in an Acss2/HIF-2 dependent manner. Finally, Acss2 in human colon cancer samples is most frequently localized in the nucleus, consistent with it having a signaling role. Targeted inhibition of Acss2/HIF-2 signaling may have synergistic effects for some colon cancer patients.

FNBP4 is a Potential Biomarker Associated with Cuproptosis and Promotes Tumor Progression in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors that lacks an efficient therapeutic approach because of its elusive molecular mechanisms. This study aimed to investigate the biological function and potential mechanism of formin-binding protein 4 (FNBP4) in HCC.

Methods

FNBP4 expression in tissues and cells were detected by quantitative real-time PCR (qRT‒PCR), Western blot, and immunohistochemistry (IHC). The Kaplan-Meier method was used to explore the correlation between the FNBP4 expression and clinical survival. MTT, EdU incorporation, colony formation, and Transwell assays were performed to evaluate the function of FNBP4 in cell proliferation and migration in vitro. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was used to explore the potential mechanism of FNBP4. The prognostic risk signature and nomogram were constructed to demonstrate the prognostic value of FNBP4.

Results

We found that FNBP4 was upregulated in patients with HCC and associated with poor overall survival (OS). Furthermore, knockdown of FNBP4 inhibited the proliferation and migration in HCC cells. Then, we performed a KEGG pathway analysis of the coexpressed genes associated with FNBP4 and found that FNBP4 may be associated with tumor-related signaling pathways and cuproptosis. We verified that FNBP4 could cause cell cycle progression and inactivation of the hippo signaling pathway. A prognostic risk signature containing three FNBP4-related differentially expressed cuproptosis regulators (DECRs) was established and can be used as an independent risk factor to evaluate the prognosis of patients with HCC. In addition, a nomogram including a risk score and clinicopathological factors was used to predict patient survival probabilities.

Conclusion

FNBP4, as a potential biomarker associated with cuproptosis, promotes HCC cell proliferation and metastasis. We provide a new potential strategy for HCC treatment by targeting FNBP4.

Fecal microbiota transplantation in a rodent model of short bowel syndrome: A therapeutic approach?

Extensive intestinal resection leads to Short Bowel Syndrome (SBS), the main cause of chronic intestinal failure. Colon preservation is crucial for spontaneous adaptation, to improve absorption and reduce parenteral nutrition dependence. Fecal microbiota transplantation (FMT), a promising approach in pathologies with dysbiosis as the one observed in SBS patients, was assessed in SBS rats with jejuno-colonic anastomosis. The evolution of weight and food intake, the lenght of intestinal villi and crypts and the composition of fecal microbiota of Sham and SBS rats, transplanted or not with high fat diet rat microbiota, were analyzed. All SBS rats lost weight, increased their food intake and exhibited jejunal and colonic hyperplasia. Microbiota composition of SBS rats, transplanted or not, was largely enriched with Lactobacillaceae, and α- and β-diversity were significantly different from Sham. The FMT altered microbiota composition and α- and β-diversity in Sham but not SBS rats. FMT from high fat diet rats was successfully engrafted in Sham, but failed to take hold in SBS rats, probably because of the specific luminal environment in colon of SBS subjects favoring aero-tolerant over anaerobic bacteria. Finally, the level of food intake in SBS rats was positively correlated with their Lactobacillaceae abundance. Microbiota transfer must be optimized and adapted to this specific SBS environment.

Acetate accumulation and regulation by process parameters control in Chinese hamster ovary cell culture

Chinese hamster ovary (CHO) cells represent a group of predominantly used mammalian hosts for producing recombinant therapeutic proteins. Known for their rapid proliferation rates, CHO cells undergo aerobic glycolysis that is characterized by fast glucose consumption, that ultimately gives rise to a group of small-molecule organic acids. However, only the function of lactate has been extensively studied in CHO cell culture. In this study, we observed the accumulation of acetate from the late exponential phase to harvest day, potentially contributing to the pH decline in late culture stage regardless of lactate consumption. In addition, we evaluated the acidification of the fresh media and the cell culture suspension, and the data revealed that acetate presented a lower acidification capacity compared to lactate and exhibited limited inhibitory effect on cells with less than 20 mM supplemented in the media. This study also explored the ways to control acetate accumulation in CHO cell culture by manipulating the process parameters such as temperature, glucose, and pH control. The positive correlation between the specific glucose consumption rate and acetate generation rate provides evidence of the endogenous acetate generation from overflow metabolism. Reducing these parameters (temperature, glucose consumption) and HCl-controlled low pH ultimately suppress acetate build-up. In addition, the specific acetate generation rate and relevant glucose consumption rate are found to be a metabolic trait associated with specific cell lines. Taken together, the results presented in these experiments provide a means to advance industrial CHO cell culture process control and development.

All Fiber is Not Fiber

PURPOSE OF REVIEW

Epidemiologic studies and clinical trials have demonstrated the benefits of dietary fiber. This occurs through a combination of the physiochemical properties of fiber and through microbial fermentation that occurs in the colon which result in the production of short-chain fatty acids (SCFA). The purpose of this review is to highlight the physiochemical properties of fiber that result in the range of physiologic effects and to review the literature on the health benefits of acetate, propionate, and butyrate.

RECENT FINDINGS

Of the variety of properties and functions exerted by dietary fibers, the fermentability and production of SCFA's are emphasized in this review. Studies done in both animal and humans reveal the anti-obesity, anti-inflammatory, and possible anti-neoplastic roles SCFAs exert at the mucosal level. Many clinical questions remain regarding the optimal dose, type, and method of delivery of fiber to exert the desired beneficial effects. It has the potential to be used in the management of clinical symptoms, prevention of disease, and improvement in human health. Further studies to address this novel use of fiber has the potential to make a large impact in clinical practice.

Glyceryl triacetate feeding in mice increases plasma acetate levels but has no anticonvulsant effects in acute electrical seizure models

INTRODUCTION

Acetate has been shown to have neuroprotective and anti-inflammatory effects. It is oxidized by astrocytes and can thus provide auxiliary energy to the brain in addition to glucose. Therefore, we hypothesized that it may protect against seizures, which is investigated here by feeding glyceryl triacetate (GTA), to provide high amounts of acetate without raising sodium or acid levels.

METHOD

CD1 male mice were fed controlled diets with or without GTA for up to three weeks. Body weights, blood glucose levels, plasma short-chain fatty acid levels, and other hematological parameters were monitored. Seizure thresholds were determined in 6 Hz and maximal electroshock seizure threshold (MEST) tests. Antioxidant capacities were evaluated in the cerebral cortex and plasma using a ferric reducing antioxidant power (FRAP) assay and Trolox equivalent antioxidant capacity assay.

RESULTS

Body weight gain was similar with both diets with and without GTA in two experiments. Glyceryl triacetate-fed groups showed 2-3- and 1.6-fold increased acetate and propionate levels in plasma, respectively. Glucose levels were unaltered in blood collected from the tail tip but increased in trunk blood. No differences were found in the activity of cerebral cortex acetyl-CoA synthetase. In the 6 Hz threshold test, seizure thresholds were lower by 3 mA and 2.4 mA after 8 and 14 days, respectively, in the GTA compared to the control diet-fed group, but showed no difference on day 16, showing that GTA has small, but inconsistent proconvulsant effects in this model. In MEST tests, a slightly increased seizure threshold (1 mA) was found on day 19 in the GTA-fed group, but not in another experiment on day 21. There were no differences in antioxidant capacity in plasma or cortex between the two groups.

CONCLUSION

Glyceryl triacetate feeding showed no antioxidant effects nor beneficial changes in acute electrical seizure threshold mouse models, despite its ability to increase plasma acetate levels.

Inulin supplementation prior to mild traumatic brain injury mitigates gut dysbiosis, and brain vascular and white matter deficits in mice

Introduction

Mild traumatic brain injury (mTBI) has been shown to negatively alter bacterial diversity and composition within the gut, known as dysbiosis, in rodents and humans. These changes cause secondary consequences systemically through decreased bacterial metabolites such as short chain fatty acids (SCFAs) which play a role in inflammation and metabolism. The goal of the study was to identify if giving prebiotic inulin prior to closed head injury (CHI) could mitigate gut dysbiosis, increase SCFAs, and improve recovery outcomes, including protecting cerebral blood flow (CBF) and white matter integrity (WMI) in young mice.

Methods

We fed mice at 2 months of age with either inulin or control diet (with cellulose as fiber source) for two months before the CHI and continued till the end of the study. We analyzed gut microbiome composition and diversity, determined SCFAs levels, and measured CBF and WMI using MRI. We compared the results with Naïve and Sham-injury mice at 24 hours, 1.5 months, and 3-4 months post-injury.

Results

We found that both CHI and Sham mice had time-dependent changes in gut composition and diversity after surgery. Inulin significantly reduced the abundance of pathobiont bacteria, such as E. coli, Desulfovibrio spp and Pseudomonas aeruginosa, in Sham and CHI mice compared to mice fed with control diet. On the other hand, inulin increased SCFAs-producing bacteria, such as Bifidobacterium spp and Lactobacillus spp, increased levels of SCFAs, including butyrate and propionate, and significantly altered beta diversity as early as 24 hours post-injury, which lasted up to 3-4 months post-injury. The mitigation of dysbiosis is associated with protection of WMI in fimbria, internal and external capsule, and CBF in the right hippocampus of CHI mice, suggesting protection of memory and cognitive functions.

Discussion

The results indicate that giving inulin prior to CHI could promote recovery outcome through gut microbiome modulation. As inulin, microbiome analysis, and MRI are readily to be used in humans, the findings from the study may pave a way for a cost-effective, accessible intervention for those at risk of sustaining a head injury, such as military personnel or athletes in contact sports.

Transcriptional Regulation of Human Arylamine N-Acetyltransferase 2 Gene by Glucose and Insulin in Liver Cancer Cell Lines

Arylamine N-acetyltransferase 2 (NAT2) is well-known for its role in phase II metabolism of xenobiotics and drugs. More recently, genome wide association studies and murine models implicated NAT2 in regulation of insulin sensitivity and plasma lipid levels. However, the mechanism remains unknown. Transcript levels of human NAT2 varied dynamically in HepG2 (hepatocellular) cells, depending on the nutrient status of the culture media. Culturing the cells in the presence of glucose induced NAT2 mRNA expression as well as its N-acetyltransferase activity significantly. In addition, insulin or acetate treatment also significantly induced NAT2 mRNA. We examined and compared the glucose- and acetate-dependent changes in NAT2 expression to those of genes involved in glucose and lipid metabolism, including FABP1, CPT1A, ACACA, SCD, CD36, FASN, ACLY, G6PC, and PCK1. Genes that are involved in fatty acid transport and lipogenesis, such as FABP1 and CD36, shared a similar pattern of expression with NAT2. In silico analysis of genes co-expressed with NAT2 revealed an enrichment of biological processes involved in lipid and cholesterol biosynthesis and transport. Among these, A1CF (APOBEC1 complementation factor) showed the highest correlation with NAT2 in terms of its expression in normal human tissues. The current study shows, for the first time, that human NAT2 is transcriptionally regulated by glucose and insulin in liver cancer cell lines and that the gene expression pattern of NAT2 is similar to that of genes involved in lipid metabolism and transport.

Changes in Soil Characteristics, Microbial Metabolic Pathways, TCA Cycle Metabolites and Crop Productivity following Frequent Application of Municipal Solid Waste Compost

The benefit sof municipal solid waste (MSW) compost on soil health and plant productivity are well known, but not its long-term effect on soil microbial and plant metabolic pathways. A 5-year study with annual (AN), biennial (BI) and no (C, control) MSW compost application were carried out to determine the effect on soil properties, microbiome function, and plantgrowth and TCA cycle metabolites profile of green beans (Phaseolus vulgaris), lettuce (Latuca sativa) and beets (Beta vulgaris). MSW compost increased soil nutrients and organic matter leading to a significant (p < 0.05) increase in AN-soil water-holding capacity followed by BI-soil compared to C-soil. Estimated nitrogen release in the AN-soil was ca. 23% and 146% more than in BI-soil and C-soil, respectively. Approximately 44% of bacterial community due to compost. Deltaproteobacteria, Bacteroidetes Bacteroidia, and Chloroflexi Anaerolineae were overrepresented in compost amended soils compared to C-soil. A strong positive association existed between AN-soil and 18 microbial metabolic pathways out of 205. Crop yield in AN-soil were increased by 6−20% compared to the BI-soil, and by 35−717% compared to the C-soil. Plant tricarboxylic acid cycle metabolites were highly (p < 0.001) influenced by compost. Overall, microbiome function and TCA cycle metabolites and crop yield were increased in the AN-soil followed by the BI-soil and markedly less in C-soil. Therefore, MSW compost is a possible solution to increase soil health and plants production in the medium to long term. Future study must investigate rhizosphere metabolic activities.

Transcription factors TEAD2 and E2A globally repress acetyl-CoA synthesis to promote tumorigenesis

Acetyl-coenzyme A (acetyl-CoA) plays an important role in metabolism, gene expression, signaling, and other cellular processes via transfer of its acetyl group to proteins and metabolites. However, the synthesis and usage of acetyl-CoA in disease states such as cancer are poorly characterized. Here, we investigated global acetyl-CoA synthesis and protein acetylation in a mouse model and patient samples of hepatocellular carcinoma (HCC). Unexpectedly, we found that acetyl-CoA levels are decreased in HCC due to transcriptional downregulation of all six acetyl-CoA biosynthesis pathways. This led to hypo-acetylation specifically of non-histone proteins, including many enzymes in metabolic pathways. Importantly, repression of acetyl-CoA synthesis promoted oncogenic dedifferentiation and proliferation. Mechanistically, acetyl-CoA synthesis was repressed by the transcription factors TEAD2 and E2A, previously unknown to control acetyl-CoA synthesis. Knockdown of TEAD2 and E2A restored acetyl-CoA levels and inhibited tumor growth. Our findings causally link transcriptional reprogramming of acetyl-CoA metabolism, dedifferentiation, and cancer.

Enhancing microalgal lipid accumulation for biofuel production

Microalgae have high lipid accumulation capacity, high growth rate and high photosynthetic efficiency which are considered as one of the most promising alternative sustainable feedstocks for producing lipid-based biofuels. However, commercialization feasibility of microalgal biofuel production is still conditioned to the high production cost. Enhancement of lipid accumulation in microalgae play a significant role in boosting the economics of biofuel production based on microalgal lipid. The major challenge of enhancing microalgal lipid accumulation lies in overcoming the trade-off between microalgal cell growth and lipid accumulation. Substantial approaches including genetic modifications of microalgal strains by metabolic engineering and process regulations of microalgae cultivation by integrating multiple optimization strategies widely applied in industrial microbiology have been investigated. In the present review, we critically discuss recent trends in the application of multiple molecular strategies to construct high performance microalgal strains by metabolic engineering and synergistic strategies of process optimization and stress operation to enhance microalgal lipid accumulation for biofuel production. Additionally, this review aims to emphasize the opportunities and challenges regarding scaled application of the strategic integration and its viability to make microalgal biofuel production a commercial reality in the near future.

Cuproptosis regulator-mediated patterns associated with immune infiltration features and construction of cuproptosis-related signatures to guide immunotherapy

Background

Liver hepatocellular carcinoma (HCC) is a prevalent cancer that lacks a sufficiently efficient approach to guide immunotherapy. Additionally, cuproptosis is a recently identified regulated cell death program that is triggered by copper ionophores. However, its possible significance in tumor immune cell infiltration is still unclear.

Methods

Cuproptosis subtypes in HCC were identified using unsupervised consensus cluster analysis based on 10 cuproptosis regulators expressions, and a cuproptosis-related risk signature was generated using univariate and LASSO Cox regression and validated using the ICGC data. Moreover, the relationship between signature and tumor immune microenvironment (TME) was studied through tumor immunotherapy responsiveness, immune cell infiltration, and tumor stem cell analysis. Finally, clinical specimens were analyzed using immunohistochemistry to verify the expression of the three genes in the signature.

Results

Two subtypes of cuproptosis regulation were observed in HCC, with different immune cell infiltration features. Genes expressed differentially between the two cuproptosis clusters in the TCGA were determined and used to construct a risk signature that was validated using the ICGC cohort. Greater immune and stromal cell infiltration were observed in the high-risk group and were associated with unfavorable prognosis. Elevated risk scores were linked with higher RNA stemness scores (RNAss) and tumor mutational burden (TMB), together with a greater likelihood of benefitting from immunotherapy.

Conclusion

It was found that cuproptosis regulatory patterns may play important roles in the heterogeneity of immune cell infiltration. The risk signature associated with cuproptosis can assess each patient's risk score, leading to more individualized and effective immunotherapy.

Lipid metabolism in pancreatic cancer: emerging roles and potential targets

Pancreatic cancer is one of the most serious health issues in developed and developing countries, with a 5-year overall survival rate currently <9%. Patients typically present with advanced disease due to vague symptoms or lack of screening for early cancer detection. Surgical resection represents the only chance for cure, but treatment options are limited for advanced diseases, such as distant metastatic or locally progressive tumors. Although adjuvant chemotherapy has improved long-term outcomes in advanced cancer patients, its response rate is low. So, exploring other new treatments is urgent. In recent years, increasing evidence has shown that lipid metabolism can support tumorigenesis and disease progression as well as treatment resistance through enhanced lipid synthesis, storage, and catabolism. Therefore, a better understanding of lipid metabolism networks may provide novel and promising strategies for early diagnosis, prognosis estimation, and targeted therapy for pancreatic cancer patients. In this review, we first enumerate and discuss current knowledge about the advances made in understanding the regulation of lipid metabolism in pancreatic cancer. In addition, we summarize preclinical studies and clinical trials with drugs targeting lipid metabolic systems in pancreatic cancer. Finally, we highlight the challenges and opportunities for targeting lipid metabolism pathways through precision therapies in pancreatic cancer.

Metabolic and Cellular Compartments of Acetyl-CoA in the Healthy and Diseased Brain

The human brain is characterised by the most diverse morphological, metabolic and functional structure among all body tissues. This is due to the existence of diverse neurons secreting various neurotransmitters and mutually modulating their own activity through thousands of pre- and postsynaptic interconnections in each neuron. Astroglial, microglial and oligodendroglial cells and neurons reciprocally regulate the metabolism of key energy substrates, thereby exerting several neuroprotective, neurotoxic and regulatory effects on neuronal viability and neurotransmitter functions. Maintenance of the pool of mitochondrial acetyl-CoA derived from glycolytic glucose metabolism is a key factor for neuronal survival. Thus, acetyl-CoA is regarded as a direct energy precursor through the TCA cycle and respiratory chain, thereby affecting brain cell viability. It is also used for hundreds of acetylation reactions, including N-acetyl aspartate synthesis in neuronal mitochondria, acetylcholine synthesis in cholinergic neurons, as well as divergent acetylations of several proteins, peptides, histones and low-molecular-weight species in all cellular compartments. Therefore, acetyl-CoA should be considered as the central point of metabolism maintaining equilibrium between anabolic and catabolic pathways in the brain. This review presents data supporting this thesis.

Dietary Fibre and Organic Acids in Kiwifruit Suppress Glycaemic Response Equally by Delaying Absorption-A Randomised Crossover Human Trial with Parallel Analysis of 13C-Acetate Uptake

Non-sugar components of kiwifruit reduce the amplitude of the glycaemic response to co-consumed cereal starch. We determined the relative contribution of different non-sugar kiwifruit components to this anti-glycaemic effect. Healthy participants (n = 9) ingested equal carbohydrate meals containing 20 g starch as wheat biscuit (WB, 30 g), and the sugar equivalent of two kiwifruit (KFsug, 20.4 g), either intrinsic or added as glucose, fructose and sucrose (2:2:1). The meals were WB+KFsug (control, no non-sugar kiwifruit components), WB + whole kiwifruit pulp (WB+KF), WB + neutralised kiwifruit pulp (WB+KFneut), WB + low-fibre kiwifruit juice (WB+KFjuice) and WB+KFsug + kiwifruit organic acids (WB+KFsug+OA). All meals were spiked with 100 mg sodium [1-13C] acetate to measure intestinal absorption. Each participant ingested all meals in random order. Blood glucose and breath 13CO2 were measured at ingestion and at 15 min intervals up to 180 min. Compared with WB+KFsug, whole kiwifruit pulp (WB+KF) almost halved glycaemic response amplitude (p < 0.001), reduced incremental area under the blood glucose response curve (iAUC) at 30 min (peak) by 50% (p < 0.001), and averted late postprandial hypoglycaemia. All other treatments suppressed response amplitude half as much as whole kiwifruit and averted acute hypoglycaemia, with little effect on iAUC. Effects on 13CO2 exhalation paralleled effects on blood glucose (R2 = 0.97). Dietary fibre and organic acids contributed equally to the anti-glycaemic effect of kiwifruit by reducing intestinal absorption rate. Kiwifruit flesh effectively attenuates glycaemic response in carbohydrate exchange, as it contains fructose, dietary fibre and organic acids.

18F-FDG /18F-Choline Dual-Tracer PET Behavior and Tumor Differentiation in HepatoCellular Carcinoma. A Systematic Review

Background

Post-operative recurrence remains the strongest prognostic factor of resected hepatocellular carcinoma (HCC), making the accurate selection of patients with curable HCC a crucial issue. PET imaging combining both 18F-FDG and fatty acid synthase (FAS) radiotracers—such as Choline—has shown its interest for the initial staging and therapeutic management of patients with HCC, but its use is still not consensual. Importantly, the very first dual-tracer PET studies suggested 18F-FDG/FAS PET behavior be linked to the degree of differentiation of HCC, a major predictive factor of post-operative recurrence. Although this key molecular imaging concept may impact how dual-tracer PET will be used in early-stage HCC, its level of evidence remains largely unexplored. In this study, we conducted a systematic review of the available evidence-based data to clarify the relevance of dual 18F-FDG/18F-Choline PET in characterizing the degree of differentiation of HCC tumors.

Methods

A systematic search of the PubMed/Medline and Embase databases was performed up to November 2021. A systematic review of the dual-tracer 18F-FDG/18F-Choline PET behavior of histology-proven HCC according to their degree of differentiation was conducted. The overall quality of the included studies was critically assessed based on the STROBE guidelines. Information on study date, design, patient cohort characteristics, grade of differentiation of HCC tumors, and the dual-tracer PET behavior per HCC was independently extracted and summarized.

Results

From 440 records initially available, 6 full-text articles (99 histology-proven HCC) provided dual-tracer 18F-FDG/18F-Choline PET behavior per HCC tumor grade were included in the systematic review. Based on our analysis, 43/99 HCCs were reported to be well-differentiated, and 56/99 HCCs were reported to be less-differentiated tumors. In the well-differentiated subgroup, more than half were exclusively positive for 18F-Choline (51%), whereas 39% were positive for both 18F-FDG and 18F-Choline. In the less-differentiated subgroup, 37% of HCC patients were positive exclusively for FDG, 36% were positive for both 18F-FDG and 18F-Choline, and 25% were positive exclusively for 18F-Choline.

Conclusion

The 18F-FDG/18F-Choline dual-tracer PET behavior of uptake shows high overlap between well- and less differentiated HCC, making the characterization of tumors challenging based on such PET combination alone. Given our growing knowledge of the molecular complexity of HCC, further studies are necessary to refine our understanding of radiotracers’ behavior in this field and improve the usefulness of PET imaging in the clinical decision process of HCC.

Acetyl-CoA synthetase 2(ACSS2): a review with a focus on metabolism and tumor development

Acetyl-CoA synthetase 2 (ACSS2), an important member of the acetyl-CoA synthetase (ACSS) family, can catalyze the conversion of acetate to acetyl coenzyme A (acetyl-CoA). Currently, acetyl-CoA is considered an important intermediate metabolite in the metabolism of energy substrates. In addition, nutrients converge through acetyl-CoA into a common metabolic pathway, the tricarboxylic acid cycle and oxidative phosphorylation. Not only does ACSS2 play a crucial role in material energy metabolism, it is also involved in the regulation of various acetylation processes, such as regulation of histone and transcription factor acetylation. ACSS2-mediated regulation of acetylation is related to substance metabolism and tumorigenesis. In mammalian cells, ACSS2 utilizes intracellular acetate to synthesize acetyl-CoA, a step in the process of DNA and histone acetylation. In addition, studies in tumors have shown that cancer cells adapt to the growth conditions in the tumor microenvironment (TME) by activating or increasing the expression level of ACSS2 under metabolic stress. Therefore, this review mainly outlines the role of ACSS2 in substance metabolism and tumors and provides insights useful for investigating ACSS2 as a therapeutic target.

Dietary Macroalgae Saccharina japonica Ameliorates Liver Injury Induced by a High-Carbohydrate Diet in Swamp Eel (Monopterus albus)

A high-carbohydrate diet lowers the rearing cost and decreases the ammonia emission into the environment, whereas it can induce liver injury, which can reduce harvest yields and generate economic losses in reared fish species. Macroalgae Saccharina japonica (SJ) has been reported to improve anti-diabetic, but the protective mechanism of dietary SJ against liver injury in fish fed a high-carbohydrate diet has not been studied. Therefore, a 56-day nutritional trial was designed for swamp eel Monopterus albus, which was fed with the normal diet [20% carbohydrate, normal carbohydrate (NC)], a high carbohydrate diet (32% carbohydrate, HC), and a HC diet supplemented with 2.5% SJ (HC-S). The HC diet promoted growth and lowered feed coefficient (FC), whereas it increased hepatosomatic index (HSI) when compared with the NC diet in this study. However, SJ supplementation increased iodine contents in muscle, reduced HSI, and improved liver injury, such as the decrease of glucose (GLU), total bile acid (TBA), and alanine aminotransferase (ALT) in serum, and glycogen and TBA in the liver. Consistently, histological analysis showed that SJ reduced the area of lipid droplet, glycogen, and collagen fiber in the liver (p < 0.05). Thoroughly, the underlying protective mechanisms of SJ supplementation against HC-induced liver injury were studied by liver transcriptome sequencing coupled with pathway analysis. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the differentially expressed genes (DEGs), such as the acetyl-coenzyme A synthetase (acss1), alcohol dehydrogenase (adh), interferon-induced protein with tetratricopeptide repeats 1 (ifit1), aldo-keto reductase family 1 member D1 (akr1d1), cholesterol 7-alpha-monooxygenase (cyp7a1), and UDP-glucuronosyltransferase (ugt), indicated that the pathway of glycolysis/gluconeogenesis was the main metabolic pathway altered in the HC group compared with the NC group. Meanwhile, hepatitis C, primary BA biosynthesis, and drug metabolism-cytochrome P450 were the three main metabolic pathways altered by SJ supplementation when compared with the HC group. Moreover, the BA-targeted metabolomic analysis of the serum BA found that SJ supplementation decreased the contents of taurohyocholic acid (THCA), taurochenodeoxycholic acid (TCDCA), taurolithocholic acid (TLCA), nordeoxycholic acid (NorDCA), and increased the contents of ursocholic acid (UCA), allocholic acid (ACA), and chenodeoxycholic acid (CDCA). In particular, the higher contents of UCA, ACA, and CDCA regulated by SJ were associated with lower liver injury. Overall, these results indicate that the 2.5% supplementation of SJ can be recommended as a functional feed additive for the alleviation of liver injury in swamp eel-fed high-carbohydrate diets.

Metabolomic Profiling of Samples from Pediatric Asthma Patients Unveils Deficient Nutrients in African Americans

Plasma metabolomics represents a potentially powerful approach to understand the biochemical mechanisms of nutrition and metabolism in asthma. This study aims to acquire knowledge on plasma metabolites in asthma, which may provide avenues for nutrition therapy, as well as explanations for the observed effects in existing therapies. This study investigated 249 metabolites from 18 metabolite groups in a large cohort of African American population, including 602 pediatric patients with asthma and 593 controls, using a nuclear magnetic resonance (NMR) metabolomics platform. Decreased levels of citrate, ketone bodies, and two amino acids histidine (His) and glutamine (Gln), were observed in asthma cases compared to controls. Metabolites for lipid metabolism lost significance after controlling for comorbid obesity. For the first time, this study depicts a broad panorama of lipid metabolism and nutrition in asthma. Supplementation or augmentation of nutrients that are deficient may be beneficial for asthma care.

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Asthma is a major health issue in African Americans

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Metabolomics represents a powerful approach to understand the metabolism in asthma

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We observed decreased citrate, ketone bodies, and amino acids in the plasma

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Supplementation of nutrients that are deficient may be beneficial for asthma care

Integration of Eukaryotic Energy Metabolism: The Intramitochondrial and Cytosolic Energy States ([ATP]f/[ADP]f[Pi])

Maintaining a robust, stable source of energy for doing chemical and physical work is essential to all living organisms. In eukaryotes, metabolic energy (ATP) production and consumption occurs in two separate compartments, the mitochondrial matrix and the cytosol. As a result, understanding eukaryotic metabolism requires knowledge of energy metabolism in each compartment and how metabolism in the two compartments is coordinated. Central to energy metabolism is the adenylate energy state ([ATP]/[ADP][Pi]). ATP is synthesized by oxidative phosphorylation (mitochondrial matrix) and glycolysis (cytosol) and each compartment provides the energy to do physical work and to drive energetically unfavorable chemical syntheses. The energy state in the cytoplasmic compartment has been established by analysis of near equilibrium metabolic reactions localized in that compartment. In the present paper, analysis is presented for energy-dependent reactions localized in the mitochondrial matrix using data obtained from both isolated mitochondria and intact tissues. It is concluded that the energy state ([ATP]_f/[ADP]_f[Pi]) in the mitochondrial matrix, calculated from the free (unbound) concentrations, is not different from the energy state in the cytoplasm. Corollaries are: (1) ADP in both the cytosol and matrix is selectively bound and the free concentrations are much lower than the total measured concentrations; and (2) under physiological conditions, the adenylate energy states in the mitochondrial matrix and cytoplasm are not substantially different.

ATP-citrate lyase (ACLY) inhibitors as therapeutic agents: a patenting perspective

INTRODUCTION

ATP citrate lyase (ACLY) is a key enzyme in cellular metabolism, being the main source of acetyl-Coenzyme A, an important precursor for fatty acid, cholesterol and isoprenoid biosynthesis, and it is also involved in protein acetylation. Its expression changes are related to hyperlipidemia and cardiovascular diseases. Other studies have shown that ACLY is closely related to the occurrence of cancer: the increase in lipid synthesis provides the necessary building blocks for cell growth and division. Therefore, finding effective ACLY inhibitors has very important application prospects for lipid-related pathologies and cancer.

AREAS COVERED

: This review covers patents concerning ACLY inhibitors and alternative strategies to modulate ACLY activity, with their potential therapeutic applications.

EXPERT OPINION

In recent years ACLY as a drug target has become a hot spot in the research of innovative drugs for disorders of glucose and lipid metabolism. Many types of small-molecule ACLY inhibitors have been discovered, but few ACLY inhibitors proved to be highly effective in vitro and in vivo, since their main limitations were low cell penetration and low affinity to ACLY. The search for new effective ACLY inhibitors is of great significance and has broad application prospects for the treatment of hyperlipidemia and cancer.

Therapeutic Targeting of Nonalcoholic Fatty Liver Disease by Downregulating SREBP-1C Expression via AMPK-KLF10 Axis

Krüppel-like factor 10 (KLF10) is a phospho-regulated transcriptional factor involved in many biological processes including lipogenesis; however, the transcriptional regulation on lipogenesis by KLF10 remains largely unclear. Lipogenesis is important in the development of nonalcoholic fatty liver disease (NAFLD) which was known regulated mainly by AMP-activated protein kinase (AMPK) and sterol regulatory element-binding protein (SREBP-1C). Interesting, our previous study using phosphorylated site prediction suggested a regulation of AMPK on KLF10. Therefore, we aimed to study the protein–protein interactions of AMPK on the regulation of KLF10, and to delineate the mechanisms of phosphorylated KLF10 in the regulation of NAFLD through SREBP-1C. We performed in vitro and in vivo assays that identified AMPK phosphorylates KLF10 at Thr189 and subsequently modulates the steady state level of KLF10. Meanwhile, a chromatin immunoprecipitation–chip assay revealed the novel target genes and signaling cascades of corresponding to phosphorylated KLF10. SREBP-1C was identified as a target gene suppressed by phosphorylated KLF10 through promoter binding. We further performed high-fat-diet-induced NAFLD models using hepatic-specific KLF10 knockout mice and wild-type mice and revealed that KLF10 knockout markedly led to more severe NAFLD than that in wild-type mice. Taken together, our findings revealed for the first time that AMPK activates and stabilizes the KLF10 protein via phosphorylation at Thr189, thereby repressing the expression of SREBP-1C and subsequent lipogenesis pathways along with metabolic disorders. We suggested that the targeted manipulation of liver metabolism, particularly through increased KLF10 expression, is a potential alternative solution for treating NAFLD.

Fatty acid metabolism and acyl-CoA synthetases in the liver-gut axis

Fatty acids are energy substrates and cell components which participate in regulating signal transduction, transcription factor activity and secretion of bioactive lipid mediators. The acyl-CoA synthetases (ACSs) family containing 26 family members exhibits tissue-specific distribution, distinct fatty acid substrate preferences and diverse biological functions. Increasing evidence indicates that dysregulation of fatty acid metabolism in the liver-gut axis, designated as the bidirectional relationship between the gut, microbiome and liver, is closely associated with a range of human diseases including metabolic disorders, inflammatory disease and carcinoma in the gastrointestinal tract and liver. In this review, we depict the role of ACSs in fatty acid metabolism, possible molecular mechanisms through which they exert functions, and their involvement in hepatocellular and colorectal carcinoma, with particular attention paid to long-chain fatty acids and small-chain fatty acids. Additionally, the liver-gut communication and the liver and gut intersection with the microbiome as well as diseases related to microbiota imbalance in the liver-gut axis are addressed. Moreover, the development of potentially therapeutic small molecules, proteins and compounds targeting ACSs in cancer treatment is summarized.