PubMed

Environ Res. 2023 Nov 20:117717. doi: 10.1016/j.envres.2023.117717. Online ahead of print.ABSTRACTUnderstanding the behavior and potential toxicity of copper nanoparticles (nano-Cu) in the aquatic environment is a primary way to assess their environmental risks. In this study, RNA-seq was performed on three different tissues (gills, intestines, and muscles) of zebrafish exposed to nano-Cu, to explore the potential toxic mechanism of nano-Cu on zebrafish. The results indicated that the toxic mechanism of nano-Cu on zebrafish was tissue-specific. Nano-Cu enables the CB1 receptor of the presynaptic membrane of gill cells to affect short-term synaptic plasticity or long-term synaptic changes (ECB-LTD) through DSI and DSE, causing dysfunction of intercellular signal transmission. Imbalance of de novo synthesis of UMP in intestinal cells and its transformation to UDP, UTP, uridine, and uracil, resulted in many functions involved in the pyrimidine metabolic pathway being blocked. Meanwhile, the toxicity of nano-Cu caused abnormal expression of RAD51 gene in muscle cells, which affects the repair of damaged DNA through Fanconi anemia and homologous recombination pathway, thus causing cell cycle disorder. These results provide insights for us to better understand the differences in toxicity of nano-Cu on zebrafish tissues and are helpful for a comprehensive assessment of nano-Cu's effects on aquatic organisms.PMID:37993046 | DOI:10.1016/j.envres.2023.117717

Front Neuroendocrinol. 2023 Nov 20:101113. doi: 10.1016/j.yfrne.2023.101113. Online ahead of print.ABSTRACTAdvances in neuroendocrinology have led to major discoveries since the 19th century, identifying adaptive loops for maintaining homeostasis. One of the most remarkable discoveries was the concept of neurosteroids, according to which the brain is not only a target but also a source of steroid production. The identification of new membrane steroid targets now underpins the neuromodulatory effects of neurosteroids such as pregnenolone, which is involved in functions mediated by the GPCR CB1 receptor. Structural analysis of steroids is a key feature of their interactions with the phospholipid membrane, receptors and resulting activity. Therefore, mass spectrometry-based methods have been developed to elucidate the metabolic pathways of steroids, the ultimate approach being metabolomics, which allows the identification of a large number of metabolites in a single sample. This approach should enable us to make progress in understanding the role of neurosteroids in the functioning of physiological and pathological processes.PMID:37993022 | DOI:10.1016/j.yfrne.2023.101113

Chemosphere. 2023 Nov 20:140767. doi: 10.1016/j.chemosphere.2023.140767. Online ahead of print.ABSTRACTGiven its wide distribution in the environment and latent toxic effects, 1,3,6,8-tetrabromo-9H-carbazole (1368-BCZ) is an emerging concern that has gained increasing attention globally. 1368-BCZ exposure is reported to have potential cardiovascular toxicity. Although atherosclerosis is a cardiovascular disease and remains a primary cause of mortality worldwide, no evidence has been found regarding the impact of 1368-BCZ on atherosclerosis. Therefore, we aimed to explore the deleterious effects of 1368-BCZ on atherosclerosis and the underlying mechanisms. Serum samples from 1368-BCZ-treated atherosclerotic model mice were subjected to metabolomic profiling to investigate the adverse influence of the pollutant. Subsequently, the molecular mechanism associated with the metabolic pathway of atherosclerotic mice that was identified following 1368-BCZ exposure was validated in vitro. Serum metabolomics analysis revealed that 1368-BCZ significantly altered the tricarboxylic acid cycle, causing a disturbance in energy metabolism. In vitro, we further validated general markers of energy metabolism based on metabolome data: 1368-BCZ dampened adenosine triphosphate (ATP) synthesis and increased reactive oxygen species (ROS) production. Furthermore, blocking the aryl hydrocarbon receptor (AhR) reversed the high production of ROS induced by 1368-BCZ. It is concluded that 1368-BCZ decreased the ATP synthesis by disturbing the energy metabolism, thereby stimulating the AhR-mediated ROS production and presumably causing aggravated atherosclerosis. This is the first comprehensive study on the cardiovascular toxicity and mechanism of 1368-BCZ based on rodent models of atherosclerosis and integrated with in vitro models.PMID:37992903 | DOI:10.1016/j.chemosphere.2023.140767

J Ethnopharmacol. 2023 Nov 20:117479. doi: 10.1016/j.jep.2023.117479. Online ahead of print.ABSTRACTETHNOPHARMACOLOGICAL RELEVANCE: Huangqi Chifeng decoction (HQCF) combined with parsnips is a classic Chinese traditional medicine formula that has certain advantages in the clinical treatment of cardiovascular and cerebrovascular diseases. At present, there is an absence of research on the regulatory effect and mechanism of this formula on atherosclerosis (AS). The synergistic effect of Radix Saposhnikoviae (RS) in HQCF is also unclear.AIM OF THE STUDY: This study was designed to investigate the role of RS, which is designed as a guide drug for HQCF, in improving the lipid metabolism of AS.MATERIALS AND METHODS: In this study, we studied the effect of HQCF on ApoE-/- mice before and after RS compatibility. Hematoxylin and eosin (HE) staining and oil red staining were used to evaluate atherosclerotic lesions and lipid accumulation in the aorta and liver, respectively. The expression of adenosine monophosphate-activated protein kinase (AMPK) and pAMPK in the aorta was measured by immunofluorescence, and AMPK and sterol regulatory element binding protein-1 (SREBP-1),fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) in liver tissue were measured by Western blot analysis. Metabolomics was used to compare the changes in serum and liver metabolites of ApoE-/- mice before and after RS combination.RESULTS: Compared with the control group, the serum lipid levels of ApoE-/- mice increased, the aortic intima thickened with plaque formation, and liver tissue pathological changes and lipid deposition occurred. Both (HQCFT without RS)HQCS and HQCF can improve the pathological condition of tissue and regulate the blood lipid level. It was noted that HQCF could promote the phosphorylation of AMPK to activate it, inhibit the expression of SREBP-1c and FAS, reduce lipid synthesis, and inhibit ACC to promote the oxidative decomposition of fatty acids. Serum and liver metabolome results showed that HQCS and HQCF treated AS mainly by regulating glycerophospholipid metabolism, sphingolipid metabolism and the arachidonic acid metabolism pathway. Importantly, HQCF showed better efficacy in regulating lipid metabolism than the HQCS group.CONCLUSION: HQCF decoction reduces atherosclerotic lesions in the aorta and lipid accumulation in the liver, which may regulate lipid transport and metabolic function by activating the AMPK pathway. These effects can be attributed to the guidance and synergism of RS.PMID:37992882 | DOI:10.1016/j.jep.2023.117479

J Pharm Sci. 2023 Nov 20:S0022-3549(23)00492-6. doi: 10.1016/j.xphs.2023.11.018. Online ahead of print.ABSTRACTCisplatin is widely used for the treatment of various types of cancer. However, cisplatin-induced nephrotoxicity (CIN) is frequently observed in patients receiving cisplatin therapy which poses a challenge in its clinical utility. Currently used clinical biomarkers for CIN are not adequate for early detection of nephrotoxicity, hence there is a need to identify potential early biomarkers in predicting CIN. In the current study, a combination of in vitro toxicodynamic (TD) modeling and untargeted global metabolomics approach was used to identify novel potential metabolite biomarkers for early detection of CIN. In addition, we investigated the protective role of cimetidine (CIM), an inhibitor of the organic cation transporter 2 (OCT2), in suppressing CIN. We first characterized the time-course of nephrotoxic effects of cisplatin (CIS) and the protective effects of CIM in a human pseudo-immortalized renal proximal tubule epithelial cell line (RPTEC), SA7K cell line. Secondly, we used a mathematical cell-level, in vitro TD modeling approach to quantitatively characterize the time-course effects of CIS and CIM as single agents and combination in SA7K cells. Based on the experimental and modeling results, we selected relevant concentrations of CIS and CIM for our metabolomics study. With the help of PCA (Principal Component Analysis) and PLS-DA (Projection to Latent Structure - Discriminate Analysis) analyses, we confirmed global metabolome changes for different groups (CIS, CIM, CIS+CIM vs control) in SA7K cells. Based on the criterion of a p-value ≤ 0.05 and a fold change ≥ 2 or ≤ 0.5, we identified 20 top metabolites that were significantly changed during the early phase i.e. within first 12 hours of CIS treatment. Finally, pathway analysis was conducted that revealed the key metabolic pathways that were most impacted in CIN.PMID:37992870 | DOI:10.1016/j.xphs.2023.11.018

Sci Total Environ. 2023 Nov 20:168572. doi: 10.1016/j.scitotenv.2023.168572. Online ahead of print.ABSTRACTImidacloprid poses a significant threat to aquatic ecosystems. In this study, we investigated the visual toxicity of imidacloprid and the underlying molecular mechanisms in adult zebrafish. After exposure to imidacloprid at environmental relevant concentrations (10 and 100μg/L) for 21 days, the detectable contents of imidacloprid were 23.0 ± 0.80 and 121 ± 1.56 ng/mg in eyes of adult zebrafish, respectively. The visual behavior of adult zebrafish was impaired including a reduced ability to track smoothly visual stimuli and visually guided self-motion. The immunofluorescence experiment showed that the content of Rhodopsin (Rho) in the retina of zebrafish was changed significantly. The expression rhythm of genes played key roles in capturing photons in dim (rho) and bright (opn1mw3, opn1lw2 and opn1sw2) light, and in phototransduction (gnb3b, arr3a and rpe65a), was disrupted significantly throughout a 24-h period in adult zebrafish. Targeted metabolomics analysis showed that the content of 16 metabolites associated with neurotransmitter function changed significantly, and were enriched in top three metabolism pathways including Arginine biosynthesis, Alanine, aspartate and glutamate metabolism, and Tryptophan metabolism. These results indicated that imidacloprid exposure at environmentally relevant concentrations could cause optical toxicity through disturbing the expression of opsins and affecting the phototransduction in the retina of zebrafish adults.PMID:37992846 | DOI:10.1016/j.scitotenv.2023.168572

J Biol Chem. 2023 Nov 20:105485. doi: 10.1016/j.jbc.2023.105485. Online ahead of print.ABSTRACTEZH2 (Enhancer of Zeste Homolog 2), a subunit of Polycomb Repressive Complex 2 (PRC2), catalyzes the trimethylation of histone H3 at lysine 27 (H3K27me3), which represses expression of genes. It also has PRC2-independent functions, including transcriptional coactivation of oncogenes, and is frequently overexpressed in lung cancers. Clinically, EZH2 inhibition can be achieved with the FDA-approved drug EPZ-6438 (tazemetostat). To realize the full potential of EZH2 blockade, it is critical to understand how cell-cell/cell-matrix interactions present in three-dimensional (3D) tissue and cell culture systems influences this blockade in terms of growth-related metabolic functions. Here, we show that EZH2 suppression reduced growth of human lung adenocarcinoma A549 cells in two-dimensional (2D) cultures but stimulated growth in 3D culture. To understand the metabolic underpinnings, we employed [13C6]-glucose Stable Isotope-Resolved Metabolomics (SIRM) to determine the effect of EZH2 suppression on metabolic networks in 2D versus 3D A549 cultures. The Krebs cycle, neoribogenesis, γ-aminobutyrate (GAB) metabolism, and salvage synthesis of purine nucleotides were activated by EZH2 suppression in 3D spheroids but not in 2D cells, consistent with the growth effect. Using simultaneous 2H7-glucose + 13C5,15N2-Gln tracers and EPZ-6438 inhibition of H3 trimethylation, we delineated the effects on the Krebs cycle, γ-aminobutyrate metabolism, gluconeogenesis, and purine salvage to be PRC2 dependent. Furthermore, the growth/metabolic effects differed for mouse Matrigel versus self-produced A549 extracellular matrix. Thus, our findings highlight the importance of the presence and nature of extracellular matrix in studying the function of EZH2 and its inhibitors in cancer cells for modeling the in vivo outcomes.PMID:37992808 | DOI:10.1016/j.jbc.2023.105485

Ecotoxicol Environ Saf. 2023 Nov 21;268:115723. doi: 10.1016/j.ecoenv.2023.115723. Online ahead of print.ABSTRACTHigh carbonate alkalinity is one of the major stress factors for survival of aquatic animals in saline-alkaline water. Exopalaemon carinicauda is a good model for studying the saline-alkaline adaption mechanism in crustacean because of its great adaptive capacity to alkalinity stress. In this study, non-targeted liquid chromatography-mass spectrometry (LC-MS) metabolomics analyses based on high-throughput RNA sequencing (RNA-Seq) were used to study the metabolomic responses of hepatopancreas in E. carinicauda at 12 h and 36 h after acute carbonate alkalinity stress. The results revealed that most of the significantly differential metabolites were related to the lipid metabolism. In particular, the sphingolipid metabolism was observed at 12 h, the glycerophospholipid metabolism was detected at 36 h, and the linoleic acid metabolic pathway was significantly enriched at both 12 h and 36 h. The combined transcriptome and metabolome analysis showed that energy consumption increased at 12 h, resulting in significant enrichment of AMPK signaling pathways, which contributed to maintain energy homeostasis. Subsequently, the hepatopancreas provided sufficient energy supply through cAMP signaling pathway and glycerophosphate metabolism to maintain normal metabolic function at 36 h. These findings might help to understand the molecular mechanisms of the E. carinicauda under carbonate alkalinity stress, thereby promote the research and development of saline-alkaline resistant shrimp.PMID:37992642 | DOI:10.1016/j.ecoenv.2023.115723

Poult Sci. 2023 Nov 6;103(1):103261. doi: 10.1016/j.psj.2023.103261. Online ahead of print.ABSTRACTThis study investigated the impacts of Wooden Breast (WB) abnormality on in vitro protein digestibility and cytotoxicity of cooked chicken breast meat. Chicken breasts without (non-WB, n = 6) or with severe WB condition (WB, n = 6) were cooked and subjected to static in vitro protein digestion. The results showed no significant differences in free-NH2, degree of hydrolysis and distribution of peptide molecular weight between non-WB and WB samples at late intestinal digestion (P5), suggesting no adverse effects of WB on protein digestibility. Based on peptidomic analysis, P5 fraction of WB showed greater content of peptides with oxidative modification than that of non-WB. Untargeted metabolomics did not find any metabolites with potential toxicity either in non-WB and WB. Hydrolyzed non-WB and WB (1.56-100 µg/mL) did not affect viability of Caco-2 and Vero cells but addition of WB samples reduced Caco-2 cell viability compared with non-WB.PMID:37992618 | DOI:10.1016/j.psj.2023.103261

Food Chem. 2023 Nov 14;438:137989. doi: 10.1016/j.foodchem.2023.137989. Online ahead of print.ABSTRACTThe pecan (Carya illinoinensis) is an important tree nut worldwide. Browning of the testa during storage considerably reduces its quality. However, the pigments that cause browning and their accumulation patterns are poorly understood. We analyzed the color changes in the testa during the five developmental stages of the kernel after storage at room temperature to compare differences in their color and identify the pigments. Samples exhibiting different colors along with their corresponding -80 °C storage samples were selected for metabolomic analysis. A total of 591 phenolic compounds were detected, 52 phenolics showed regulatory effects on testa discoloration, and 59 metabolites were identified as possible precursors of the pigments. This study revealed the most thorough phenolic composition of pecan to date. Further, the findings provide new insights into the mechanisms of testa browning, deepens our understanding of the bioactive value of pecans, and contributes to the breeding of less browning-susceptible varieties.PMID:37992607 | DOI:10.1016/j.foodchem.2023.137989

Biochem Biophys Res Commun. 2023 Nov 13;690:149242. doi: 10.1016/j.bbrc.2023.149242. Online ahead of print.ABSTRACTPURPOSE: Obesity has known detrimental effects on breast cancer (BC) development and progression. However, it's essential to consider the obesity phenotype based on metabolic health. This study aims to evaluate the impact of circulating extracellular vesicles (EVs) from women with metabolically healthy or unhealthy normal weight, overweight, and obesity on MDA-MB-231 cell migration, invasion, and apoptosis.METHODS: Plasma EVs were isolated from different obesity phenotypes in women. EVs were characterized and EVs uptake by MDA-MB-231 cells was assessed. MDA-MB-231 cell lines were treated with EVs obtained from various studied groups, and migration, invasion, MMP-2 and MMP-9 activity, Bax and Bcl-2 mRNA expression, p-53 and Thr55 p-p53 protein expression, and apoptosis were assessed.RESULTS: EVs from obese individuals, regardless of phenotype, increased invasion and MMP-2 activity compared to healthy normal-weight EVs. Normal-weight EVs led to higher invasion under unhealthy conditions. BC cell migration was enhanced by EVs from healthy obese individuals compared to healthy normal-weight EVs. EVs from unhealthy obese women exhibited significantly lower p53/p-p53 levels and reduced apoptosis compared to healthy obese groups.CONCLUSION: It appears that EVs from both normal-weight women with unhealthy conditions and those with obesity or overweight, irrespective of metabolic status, worsened the cancerous behavior of TNBC cells. Therefore, considering metabolic health, in addition to BMI, is crucial for understanding obesity-related disorders.PMID:37992524 | DOI:10.1016/j.bbrc.2023.149242

Gut Microbes. 2023 Dec;15(2):2282790. doi: 10.1080/19490976.2023.2282790. Epub 2023 Nov 22.ABSTRACTNumerous studies have described the notable impact of gut microbiota on the brain in Alzheimer's disease (AD) via the gut - brain axis. However, the molecular mechanisms underlying the involvement of gut microbiota in the development of AD are limited. This study aimed to explore the potential mechanisms of gut microbiota in AD by integrating multi-omics data. In this study, APP/PS1 and WT mice at nine months of age were used as study mouse model. Cognitive function was assessed using the Morris water maze test. The levels of Aβ plaque and neuroinflammation in the brain were detected using immunofluorescence and PET/CT. In addition, we not only used 16S rRNA gene sequencing and metabolomics to explore the variation characteristics of gut microbiota and serum metabolism abundance, but also combined spatial metabolomics and transcriptomics to explore the change in the brain and identify their potential correlation. APP/PS1 mice showed significant cognitive impairment and amyloid-β deposits in the brain. The abundance of gut microbiota was significantly changed in APP/PS1 mice, including decreased Desulfoviobrio, Enterococcus, Turicibacter, and Ruminococcus and increased Pseudomonas. The integration of serum untargeted metabolomics and brain spatial metabolomics showed that glycerophospholipid metabolism was a common alteration pathway in APP/PS1 mice. Significant proliferation and activation of astrocyte and microglia were observed in APP/PS1 mice, accompanied by alterations in immune pathways. Integration analysis and fecal microbiota transplantation (FMT) intervention revealed potential association of gut microbiota, host glycerophospholipid metabolism, and neuroinflammation levels in APP/PS1 mice.PMID:37992400 | DOI:10.1080/19490976.2023.2282790

Sci Adv. 2023 Nov 24;9(47):eadj6409. doi: 10.1126/sciadv.adj6409. Epub 2023 Nov 22.ABSTRACTPoor oxygenation (hypoxia) is a common spatially heterogeneous feature of human tumors. Biological responses to tumor hypoxia are orchestrated by the decreased activity of oxygen-dependent enzymes. The affinity of these enzymes for oxygen positions them along a continuum of oxygen sensing that defines their roles in launching reactive and adaptive cellular responses. These responses encompass regulation of all steps in the central dogma, with rapid perturbation of the metabolome and proteome followed by more persistent reprogramming of the transcriptome and epigenome. Core hypoxia response genes and pathways are commonly regulated at multiple inflection points, fine-tuning the dependencies on oxygen concentration and hypoxia duration. Ultimately, shifts in the activity of oxygen-sensing enzymes directly or indirectly endow cells with intrinsic hypoxia tolerance and drive processes that are associated with aggressive phenotypes in cancer including angiogenesis, migration, invasion, immune evasion, epithelial mesenchymal transition, and stemness.PMID:37992163 | DOI:10.1126/sciadv.adj6409

Phlebology. 2023 Nov 22:2683555231215199. doi: 10.1177/02683555231215199. Online ahead of print.ABSTRACTDeep vein thrombosis (DVT) of the lower extremities is one of the most common peripheral vascular diseases, with significant complications and sequelae. Metabolomics aims to identify small molecules in biological samples. It can serve as a promising method for screening compounds that can be used for early disease detection, diagnosis, treatment response prediction, and prognosis. In addition, high-throughput metabolomics screening can yield significant insights into the pathophysiological pathways of DVT. Currently, the metabolomic profiles of DVT have yielded inconsistent expression patterns. This article examines the recent advancements in metabolomic studies of DVT and analyzes the factors that may influence the results.PMID:37992130 | DOI:10.1177/02683555231215199

J Proteome Res. 2023 Nov 22. doi: 10.1021/acs.jproteome.3c00474. Online ahead of print.ABSTRACTSarcopenia is a progressive disorder characterized by age-related loss of skeletal muscle mass and function. Although significant progress has been made over the years to identify the molecular determinants of sarcopenia, the precise mechanisms underlying the age-related loss of contractile function remains unclear. Advances in "omics" technologies, including mass spectrometry-based proteomic and metabolomic analyses, offer great opportunities to better understand sarcopenia. Herein, we performed mass spectrometry-based analyses of the vastus lateralis from young, middle-aged, and older rhesus monkeys to identify molecular signatures of sarcopenia. In our proteomic analysis, we identified proteins that change with age, including those involved in adenosine triphosphate and adenosine monophosphate metabolism as well as fatty acid beta oxidation. In our untargeted metabolomic analysis, we identified metabolites that changed with age largely related to energy metabolism including fatty acid beta oxidation. Pathway analysis of age-responsive proteins and metabolites revealed changes in muscle structure and contraction as well as lipid, carbohydrate, and purine metabolism. Together, this study discovers new metabolic signatures and offers new insights into the molecular mechanisms underlying sarcopenia for the evaluation and monitoring of a therapeutic treatment of sarcopenia.PMID:37991985 | DOI:10.1021/acs.jproteome.3c00474

Georgian Med News. 2023 Sep;(342):108-112.ABSTRACTPurpose of the study - to characterize the metabolomic profile in patients with fatigue developing within the Long COVID, during dynamic observation. 24 patients diagnosed with U09.9 "Condition after COVID-19 unspecified" were included in a prospective study. Patients were recommended to engage in physical activity, which included moderate aerobic activity such as walking for 45 minutes a day, three days a week. Clinical assessment by scales (Modified Medical Research Council dyspnea scale; 6-minute walk test; Multidimensional fatigue inventory scale; Barthel index), and determination of metabolomic parameters were performed on days 1 and 14-18 of the study. During the observation period, lactate, fumaric acid, symmetrical dimethylarginine, asymmetric dimethylarginine remained above the reference values. The level of adipic acid returns to normal values. As a result of performing physical activity, such as walking, results on the Modified Medical Research Council scale dyspnea scale, Multidimensional fatigue inventory scale, 6 Minutes Walking Test and Barthel Index improve (p<0,001). Metabolic profile of patients with Long COVID demonstrates the complex of abnormalities at 60 days after the onset of the disease. These metabolic changes are point to possible therapeutic targets for specific pathogenetic pharmacotherapy.PMID:37991964

ACS Infect Dis. 2023 Nov 22. doi: 10.1021/acsinfecdis.3c00480. Online ahead of print.ABSTRACTCarbapenem-resistant Acinetobacter baumannii (CRAB) strains are prevalent worldwide and represent a major threat to public health. However, treatment options for infections caused by CRAB are very limited as they are resistant to most of the commonly used antibiotics. Consequently, understanding the mechanisms underlying carbapenem resistance and restoring bacterial susceptibility to carbapenems hold immense importance. The present study used gas chromatography-mass spectrometry (GC-MS)-based metabolomics to investigate the metabolic mechanisms of antibiotic resistance in clinically isolated CRAB. Inactivation of the pyruvate cycle and purine metabolism is the most typical characteristic of CRAB. The CRAB exhibited a reduction in the activity of enzymes involved in the pyruvate cycle, proton motive force, and ATP levels. This decline in central carbon metabolism resulted in a decrease in the metabolic flux of the α-ketoglutarate-glutamate-glutamine pathway toward purine metabolism, ultimately leading to a decline in adenine nucleotide interconversion. Exogenous adenosine monophosphate (AMP) and adenosine triphosphate (ATP) enhance the killing efficacy of Meropenem against CRAB. The combination of ATP and Meropenem also has a synergistic effect on eliminating CRAB persisters and the biofilm, as well as protecting mice against peritonitis-sepsis. This study presents a novel therapeutic modality to treat infections caused by CRAB based on the metabolism reprogramming strategy.PMID:37991817 | DOI:10.1021/acsinfecdis.3c00480

Elife. 2023 Nov 22;12:RP87039. doi: 10.7554/eLife.87039.ABSTRACTChanges in an organism's environment, genome, or gene expression patterns can lead to changes in its metabolism. The metabolic phenotype can be under selection and contributes to adaptation. However, the networked and convoluted nature of an organism's metabolism makes relating mutations, metabolic changes, and effects on fitness challenging. To overcome this challenge, we use the long-term evolution experiment (LTEE) with E. coli as a model to understand how mutations can eventually affect metabolism and perhaps fitness. We used mass spectrometry to broadly survey the metabolomes of the ancestral strains and all 12 evolved lines. We combined this metabolic data with mutation and expression data to suggest how mutations that alter specific reaction pathways, such as the biosynthesis of nicotinamide adenine dinucleotide, might increase fitness in the system. Our work provides a better understanding of how mutations might affect fitness through the metabolic changes in the LTEE and thus provides a major step in developing a complete genotype-phenotype map for this experimental system.PMID:37991493 | DOI:10.7554/eLife.87039

Am J Physiol Endocrinol Metab. 2023 Nov 22. doi: 10.1152/ajpendo.00151.2023. Online ahead of print.ABSTRACTCells use glycolytic intermediates for anabolism e.g., via the serine synthesis and pentose phosphate pathways. However, we still understand poorly how these metabolic pathways contribute to skeletal muscle cell biomass generation. The first aim of this study was therefore to identify enzymes that limit protein synthesis, myotube size, and proliferation in skeletal muscle cells. We inhibited key enzymes of glycolysis, the pentose phosphate pathway, and serine synthesis pathway to evaluate their importance in C2C12 myotube protein synthesis. Based on the results of this first screen, we then focused on the serine synthesis pathway enzyme phosphoglycerate dehydrogenase (PHGDH). We used two different PHGDH inhibitors and mouse C2C12 and human primary muscle cells to study the importance and function of the PHGDH. Both myoblasts and myotubes incorporated glucose-derived carbon into proteins, RNA, and lipids and we showed that PHGDH is essential in these processes. PHGDH inhibition decreased protein synthesis, myotube size, and myoblast proliferation without cytotoxic effects. The decreased protein synthesis in response to PHGDH inhibition appears to occur mainly mTORC1 dependently as was evident from experiments with insulin-like growth factor 1 and rapamycin. Further metabolomics analyses revealed that PHGDH inhibition accelerated glycolysis and altered amino acid, nucleotide, and lipid metabolism. Lastly, we found that supplementing an antioxidant and redox modulator N-acetylcysteine partially rescued the decreased protein synthesis and mTORC1 signaling during PHGDH inhibition. The data suggest that PHGDH activity is critical for skeletal muscle cell biomass generation from glucose, and that it regulates protein synthesis and mTORC1 signaling.PMID:37991454 | DOI:10.1152/ajpendo.00151.2023

Am J Physiol Endocrinol Metab. 2023 Nov 22. doi: 10.1152/ajpendo.00332.2023. Online ahead of print.ABSTRACTAcute ingestion of the exogenous ketone monoester supplement [(R)-3-hydroxybutyl-(R)-3-hydroxybutyrate] lowers blood glucose, suggesting therapeutic potential in individuals with impaired glucose metabolism. However, it is unknown how acute or repeated ingestion of exogenous ketones affect blood glucose control in individuals with type 2 diabetes (T2D). We conducted two randomized, counter-balanced, double-blind, placebo-controlled crossover trials to determine if (1) acute exogenous ketone monoester (0.3 g/kg body mass; N=18), or (2) 14-day thrice daily pre-meal exogenous ketone monoester (15 g; N=15) supplementation could lower blood glucose in individuals living with T2D. A single dose of the ketone monoester supplement elevated blood ß-OHB to ~2 mM. There were no differences in the primary outcomes of plasma glucose concentration (acutely) or serum fructosamine (glycaemic control across 14 days) between conditions. Ketone monoester ingestion acutely increased insulin and lowered non-esterified fatty acid concentrations; plasma metabolomics confirmed a reduction in multiple free fatty acids species and select gluconeogenic amino acids. In contrast, no changes were observed in fasting metabolic outcomes following 14 days of supplementation. In the context of these randomized controlled trials, acute or repeated ketone monoester ingestion in adults with T2D did not lower blood glucose when consumed acutely in a fasted state, and did not improve glycaemic control following thrice daily pre-meal ingestion across 14 days. Future studies exploring the mechanistic basis for the (lack of) glucose-lowering effect of exogenous ketone supplementation in T2D and other populations are warranted.PMID:37991451 | DOI:10.1152/ajpendo.00332.2023