Metabolic modeling of single Th17 cells reveals regulators of autoimmunity.

Metabolism is a major regulator of immune cell function, but it remains difficult to study the metabolic status of individual cells. Here, we present Compass, an algorithm to characterize cellular metabolic states based on single-cell RNA sequencing and flux balance analysis. We applied Compass to associate metabolic states with T helper 17 (Th17) functional variability (pathogenic potential) and recovered a metabolic switch between glycolysis and fatty acid oxidation, akin to known Th17/regulatory T cell (Treg) differences, which we validated by metabolic assays. Compass also predicted that Th17 pathogenicity was associated with arginine and downstream polyamine metabolism. Indeed, polyamine-related enzyme expression was enhanced in pathogenic Th17 and suppressed in Treg cells. Chemical and genetic perturbation of polyamine metabolism inhibited Th17 cytokines, promoted Foxp3 expression, and remodeled the transcriptome and epigenome of Th17 cells toward a Treg-like state. In vivo perturbations of the polyamine pathway altered the phenotype of encephalitogenic T cells and attenuated tissue inflammation in CNS autoimmunity.

Changes in soil microbial community and activity caused by application of dimethachlor and linuron.

Soil microorganisms and their activities are essential for maintaining soil health and fertility. Microorganisms can be negatively affected by application of herbicides. Although effects of herbicides on microorganisms are widely studied, there is a lack of information for chloroacetamide herbicide dimethachlor. Thus, dimethachlor and well known linuron were applied to silty-loam luvisol and their effects on microorganisms were evaluated during112 days long laboratory assay. Dimethachlor and linuron were applied in doses 1.0 kg ha-1 and 0.8 kg ha-1 corresponding to 3.33 mg kg-1 and 2.66 mg kg-1 respectively. Also 100-fold doses were used for magnification of impacts. Linuron in 100-fold dose caused minor increase of respiration, temporal increase of soil microbial biomass, decrease of soil dehydrogenase activity, and altered microbial community. Dimethachlor in 100-fold dose significantly increased respiration; microbial biomass and decreased soil enzymatic activities. Microbial composition changed significantly, Proteobacteria abundance, particularly Pseudomonas and Achromobacter genera increased from 7 to 28th day. In-silico prediction of microbial gene expression by PICRUSt2 software revealed increased expression of genes related to xenobiotic degradation pathways. Evaluated characteristics of microbial community and activity were not affected by herbicides in recommended doses and the responsible use of both herbicides will not harm soil microbial community.

Treatment with ascorbic acid normalizes the aerobic capacity, antioxidant defence, and cell death pathways in thermally stressed Mytilus galloprovincialis.

Considering temperature's upcoming increase due to climate change, combined with the fact that Mediterranean mussels Mytilus galloprovincialis (Lamarck, 1819) live at their upper limits [critical temperatures (Tc) beyond 25 °C], we cannot be sure of this species' sustainable future in the Mediterranean Sea. Deviation from optimum temperatures leads to cellular damage due to oxidative stress. Although ascorbic acid (AA) is a major scavenger of reactive oxygen species (ROS), its capacity to minimize oxidative stress effects is scarcely studied in aquatic organisms. Thus, treatment with 5 mM and 10 mM AA of thermally stressed molluscs had been employed in order to examine its antioxidant capacity. While 5 mM had no effect, 10 mM normalized COX1 and ND2 relative mRNA levels, and superoxide dismutase (SOD), catalase, and glutathione reductase (GR) enzymatic activity levels in both examined tissues: posterior adductor muscle (PAM) and mantle. ATP levels, probably providing the adequate energy for antioxidant defence in thermally stressed mussels, is also normalized under 10 mM AA treatment. Moreover, autophagic indicators such as LC3 II/I and SQSTM1/p62 levels are normalized, indicating autophagy amelioration. Apoptosis also seems to be inhibited since both Bax/Bcl-2 and cleaved caspase substrate levels decrease with 10 mM AA treatment. Therefore, treatment of mussels with AA seems to produce threshold effects, although the precise underlying mechanisms must be elucidated in future studies. These findings show that treatment of mussels with effective antioxidants can be useful as a strategic approach for the reduction of the deleterious effects on mussels' summer mortality in aquaculture zones.

Effect of respiratory inhibitors and quinone analogues on the aerobic electron transport system of Eikenella corrodens.

The effects of respiratory inhibitors, quinone analogues and artificial substrates on the membrane-bound electron transport system of the fastidious ß-proteobacterium Eikenella corrodens grown under O2-limited conditions were studied. NADH respiration in isolated membrane particles were partially inhibited by rotenone, dicoumarol, quinacrine, flavone, and capsaicin. A similar response was obtained when succinate oxidation was performed in the presence of thenoyltrifluoroacetone and N,N'-dicyclohexylcarbodiimide. NADH respiration was resistant to site II inhibitors and cyanide, indicating that a percentage of the electrons transported can reach O2 without the bc1 complex. Succinate respiration was sensitive to myxothiazol, antimycin A and 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO). Juglone, plumbagin and menadione had higher reactivity with NADH dehydrogenase. The membrane particles showed the highest oxidase activities with ascorbate-TCHQ (tetrachlorohydroquinone), TCHQ alone, and NADH-TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine), and minor activity levels with ascorbate-DCPIP (2,6-dichloro-phenolindophenol) and NADH-DCPIP. The substrates NADH-DCPIP, NADH-TMPD and TCHQ were electron donors to cyanide-sensitive cbb' cytochrome c oxidase. The presence of dissimilatory nitrate reductase in the aerobic respiratory system of E. corrodens ATCC 23834 was demonstrated by first time. Our results indicate that complexes I and II have resistance to their classic inhibitors, that the oxidation of NADH is stimulated by juglone, plumbagin and menadione, and that sensitivity to KCN is stimulated by the substrates TCHQ, NADH-DCPIP and NADH-TMPD.

Lysophosphatidic Acid Induces Aerobic Glycolysis, Lipogenesis, and Increased Amino Acid Uptake in BV-2 Microglia.

Lysophosphatidic acid (LPA) species are a family of bioactive lipids that transmit signals via six cognate G protein-coupled receptors, which are required for brain development and function of the nervous system. LPA affects the function of all cell types in the brain and can display beneficial or detrimental effects on microglia function. During earlier studies we reported that LPA treatment of microglia induces polarization towards a neurotoxic phenotype. In the present study we investigated whether these alterations are accompanied by the induction of a specific immunometabolic phenotype in LPA-treated BV-2 microglia. In response to LPA (1 µM) we observed slightly decreased mitochondrial respiration, increased lactate secretion and reduced ATP/ADP ratios indicating a switch towards aerobic glycolysis. Pathway analyses demonstrated induction of the Akt-mTOR-Hif1α axis under normoxic conditions. LPA treatment resulted in dephosphorylation of AMP-activated kinase, de-repression of acetyl-CoA-carboxylase and increased fatty acid content in the phospholipid and triacylglycerol fraction of BV-2 microglia lipid extracts, indicating de novo lipogenesis. LPA led to increased intracellular amino acid content at one or more time points. Finally, we observed LPA-dependent generation of reactive oxygen species (ROS), phosphorylation of nuclear factor erythroid 2-related factor 2 (Nrf2), upregulated protein expression of the Nrf2 target regulatory subunit of glutamate-cysteine ligase and increased glutathione synthesis. Our observations suggest that LPA, as a bioactive lipid, induces subtle alterations of the immunometabolic program in BV-2 microglia.

Glucose-dependent aerobic glycolysis contributes to recruiting viral components into HIV-1 particles to maintain infectivity.

The cellular environment affects optimal viral replication because viruses cannot replicate without their host cells. In particular, metabolic resources such as carbohydrates, lipids, and ATP are crucial for viral replication, which is sensitive to cellular metabolism. Intriguingly, recent studies have demonstrated that human immunodeficiency virus type 1 (HIV-1) infection induces a metabolic shift from oxidative phosphorylation to aerobic glycolysis in CD4+ T cells to produce the virus efficiently. However, the importance of aerobic glycolysis in maintaining the quality of viral components and viral infectivity has not yet been fully investigated. Here, we show that aerobic glycolysis is necessary not only to override the inhibitory effect of virion-incorporated glycolytic enzymes, but also to maintain the enzymatic activity of reverse transcriptase and the adequate packaging of envelope proteins into HIV-1 particles. To investigate the effect of metabolic remodeling on the phenotypic properties of HIV-1 produced by infected cells, we replaced glucose with galactose in the culture medium because the cells grown in galactose-containing medium are forced to carry out oxidative metabolism instead of aerobic glycolysis. We found that the packaging levels of glyceraldehyde 3-phosphate dehydrogenase, alpha-enolase and pyruvate kinase muscle type 2, which decrease HIV-1 infectivity by packaging into viral particles, are increased in progeny viruses produced by the cells grown in galactose-containing medium. Furthermore, we found that the entry and reverse transcription efficiency of the progeny viruses were reduced, which was caused by a decrease in the enzymatic activity of reverse transcriptase in the viral particles and a decrease in the packaging levels of envelope proteins and reverse transcriptase. These results indicate that the aerobic glycolysis environment in HIV-1-infected cells may contribute to the quality control of viruses.

LXR stimulates a metabolic switch and reveals cholesterol homeostasis as a statin target in Tasmanian devil facial tumor disease.

Devil facial tumor disease (DFTD) and its lack of available therapies are propelling the Tasmanian devil population toward extinction. This study demonstrates that cholesterol homeostasis and carbohydrate energy metabolism sustain the proliferation of DFTD cells in a cell-type-dependent manner. In addition, we show that the liver-X nuclear receptor-ß (LXRß), a major cholesterol cellular sensor, and its natural ligand 24S-hydroxycholesterol promote the proliferation of DFTD cells via a metabolic switch toward aerobic glycolysis. As a proof of concept of the role of cholesterol homeostasis on DFTD proliferation, we show that atorvastatin, an FDA-approved statin-drug subtype used against human cardiovascular diseases that inhibits cholesterol synthesis, shuts down DFTD energy metabolism and prevents tumor growth in an in vivo DFTD-xenograft model. In conclusion, we show that intervention against cholesterol homeostasis and carbohydrate-dependent energy metabolism by atorvastatin constitutes a feasible biochemical treatment against DFTD, which may assist in the conservation of the Tasmanian devil.

Impact of Lignocellulose Pretreatment By-Products on S. cerevisiae Strain Ethanol Red Metabolism during Aerobic and An-aerobic Growth.

Understanding the specific response of yeast cells to environmental stress factors is the starting point for selecting the conditions of adaptive culture in order to obtain a yeast line with increased resistance to a given stress factor. The aim of the study was to evaluate the specific cellular response of Saccharomyces cerevisiae strain Ethanol Red to stress caused by toxic by-products generated during the pretreatment of lignocellulose, such as levulinic acid, 5-hydroxymethylfurfural, furfural, ferulic acid, syringaldehyde and vanillin. The presence of 5-hydroxymethylfurfural at the highest analyzed concentration (5704.8 ± 249.3 mg/L) under aerobic conditions induced the overproduction of ergosterol and trehalose. On the other hand, under anaerobic conditions (during the alcoholic fermentation), a decrease in the biosynthesis of these environmental stress indicators was observed. The tested yeast strain was able to completely metabolize 5-hydroxymethylfurfural, furfural, syringaldehyde and vanillin, both under aerobic and anaerobic conditions. Yeast cells reacted to the presence of furan aldehydes by overproducing Hsp60 involved in the control of intracellular protein folding. The results may be helpful in optimizing the process parameters of second-generation ethanol production, in order to reduce the formation and toxic effects of fermentation inhibitors.

Frontline Science: AMPK regulates metabolic reprogramming necessary for interferon production in human plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (pDCs) play a crucial role in innate viral immunity as the most potent producers of type I interferons (IFN) in the human body. However, the metabolic regulation of IFN production in such vast quantity remains poorly understood. In this study, AMP-activated protein kinase (AMPK) is strongly implicated as a driver of metabolic reprogramming that the authors and others have observed in pDCs after activation via TLR7/9. Oxygen consumption and mitochondrial membrane potential (MMP) were elevated following stimulation of pDCs with influenza or herpes simplex virus. Blocking these changes using mitochondrial inhibitors abrogated IFN-α production. While it appears that multiple carbon sources can be used by pDCs, blocking pyruvate metabolism had the strongest effect on IFN-α production. Furthermore, we saw no evidence of aerobic glycolysis (AG) during pDC activation and blocking lactate dehydrogenase activity did not inhibit IFN-α. TLR7/9 ligation induces a posttranslational modification in Raptor that is catalyzed by AMPK, and blocking TLR7/9 before virus introduction prevents this change. Finally, it is demonstrated that Dorsomorphin, an AMPK inhibitor, inhibited both IFN-α production and MMP in a dose-dependent manner. Taken together, these data reveal a potential cellular mechanism for the metabolic reprogramming in TLR 7/9-activated pDCs that supports activation and IFN-α production.

Yeast Translation Elongation Factor eIF5A Expression Is Regulated by Nutrient Availability through Different Signalling Pathways.

Translation elongation factor eIF5A binds to ribosomes to promote peptide bonds between problematic amino acids for the reaction like prolines. eIF5A is highly conserved and essential in eukaryotes, which usually contain two similar but differentially expressed paralogue genes. The human eIF5A-1 isoform is abundant and implicated in some cancer types; the eIF5A-2 isoform is absent in most cells but becomes overexpressed in many metastatic cancers. Several reports have connected eIF5A and mitochondria because it co-purifies with the organelle or its inhibition reduces respiration and mitochondrial enzyme levels. However, the mechanisms of eIF5A mitochondrial function, and whether eIF5A expression is regulated by the mitochondrial metabolism, are unknown. We analysed the expression of yeast eIF5A isoforms Tif51A and Tif51B under several metabolic conditions and in mutants. The depletion of Tif51A, but not Tif51B, compromised yeast growth under respiration and reduced oxygen consumption. Tif51A expression followed dual positive regulation: by high glucose through TORC1 signalling, like other translation factors, to promote growth and by low glucose or non-fermentative carbon sources through Snf1 and heme-dependent transcription factor Hap1 to promote respiration. Upon iron depletion, Tif51A was down-regulated and Tif51B up-regulated. Both were Hap1-dependent. Our results demonstrate eIF5A expression regulation by cellular metabolic status.

Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic-Anaerobic Transition Zones: A Systematic Review and Meta-Analysis.

Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition zones is scarce and the results controversial. The aim of this systematic review and meta-analysis is to analyze the effects of BA supplementation on physical performance in aerobic-anaerobic transition zones. At the same time, the effect of different dosages and durations of BA supplementation were identified. The search was designed in accordance with the PRISMA® guidelines for systematic reviews and meta-analyses and performed in Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2010 and 2020. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the Time Trial Test (TTT) and Time to Exhaustion (TTE) tests, the latter separated into the Limited Time Test (LTT) and Limited Distance Test (LDT). The analysis was carried out with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI). Nineteen studies were included in the systematic review and meta-analysis, revealing a small effect for time in the TTT (SMD, -0.36; 95% CI, -0.87-0.16; I2 = 59%; p = 0.010), a small effect for LTT (SMD, 0.25; 95% CI, -0.01-0.51; I2 = 0%; p = 0.53), and a large effect for LDT (SMD, 4.27; 95% CI, -0.25-8.79; I2 = 94%; p = 0.00001). BA supplementation showed small effects on physical performance in aerobic-anaerobic transition zones. Evidence on acute supplementation is scarce (one study); therefore, exploration of acute supplementation with different dosages and formats on physical performance in aerobic-anaerobic transition zones is needed.

Antibacterial activity of SPIONs versus ferrous and ferric ions under aerobic and anaerobic conditions: a preliminary mechanism study.

In modern medicine, major attention has been paid to superparamagnetic iron oxide nanoparticles (SPIONs). Recent studies have shown the antibacterial properties of SPIONs against some Gram-positive and Gram-negative bacterial strains. These nanoparticles (NPs) can bind to bacterial membranes via hydrophobic or electrostatic interactions and pass through cell barriers. In this study, the authors evaluated the antibacterial activity of magnetic NPs in comparison with ferrous and ferric ions. The level of reactive oxygen species (ROS) in the treated Staphylococcus aureus and Escherichia coli bacteria were directly measured by fluorometric detection. The results showed that iron ions and SPIONs had significant dependent antimicrobial activities. SPIONs showed greater inhibitory effects than ferrous and ferric ions against the growth of treated bacterial strains under anaerobic conditions, while in aerobic conditions, ferrous showed the strongest antibacterial activity. In anaerobic conditions, they observed the greatest ROS formation and lowest minimum inhibitory concentration in the SPION-treated group in comparison with the other groups. It seems that the release of iron ions from SPIONs and subsequent activation of ROS pathway are the main antibacterial mechanisms of action. Nevertheless, the greater antibacterial effect of SPIONs in anaerobic conditions represents other mechanisms involved in the antibacterial activity of these NPs.

The effects of hypoxia on aerobic metabolism in oil-contaminated sea bass (Dicentrarchus labrax).

Hypoxia and petrogenic hydrocarbon contamination are two anthropogenic stressors that coexist in coastal environments. Although studies have estimated the impact of each stressor separately, few investigations have assessed the effects of these stressors in interaction. We therefore investigated the impact of these combined stressors on sea bass, (Dicentrarchus labrax) physiology. After experimental contamination with physically dispersed oil, fish were exposed to hypoxia or normoxia, and active/standard metabolic rates (AMR and SMR, respectively), and metabolic scope (MS) were estimated. At the protocol's end, the uptake of polycyclic aromatic hydrocarbons (PAHs) was estimated by evaluating relative concentrations of bile metabolites. In terms of bile metabolites, our results validated the uptake of PAHs by contaminated fish in our experimental settings, and further suggest that the hypoxic period after contamination does not reduce or increase compound metabolization processes. Our data showed significant effects of hypoxia on all metabolic rates: a significant drastic AMR reduction and significant SMR diminution led to decreased MS. We also found that oil contamination significantly impacted AMR and MS, but not SMR. These results suggested that when evaluated separately, hypoxia or oil affect the metabolic rate of sea bass. On the other hand, when evaluated in combination, no cumulative effects were observed, since fish exposed to both stressors did not show a stronger impact on metabolism than fish exposed to hypoxia alone. This suggests that oil impacts fish metabolism when fish occupy normoxic waters, and that oil does not magnify hypoxia-induced effects on fish metabolism.

Cultivation at high osmotic pressure confers ubiquinone 8-independent protection of respiration on Escherichia coli.

Ubiquinone 8 (coenzyme Q8 or Q8) mediates electron transfer within the aerobic respiratory chain, mitigates oxidative stress, and contributes to gene expression in Escherichia coli In addition, Q8 was proposed to confer bacterial osmotolerance by accumulating during growth at high osmotic pressure and altering membrane stability. The osmolyte trehalose and membrane lipid cardiolipin accumulate in E. coli cells cultivated at high osmotic pressure. Here, Q8 deficiency impaired E. coli growth at low osmotic pressure and rendered growth osmotically sensitive. The Q8 deficiency impeded cellular O2 uptake and also inhibited the activities of two proton symporters, the osmosensing transporter ProP and the lactose transporter LacY. Q8 supplementation decreased membrane fluidity in liposomes, but did not affect ProP activity in proteoliposomes, which is respiration-independent. Liposomes and proteoliposomes prepared with E. coli lipids were used for these experiments. Similar oxygen uptake rates were observed for bacteria cultivated at low and high osmotic pressures. In contrast, respiration was dramatically inhibited when bacteria grown at the same low osmotic pressure were shifted to high osmotic pressure. Thus, respiration was restored during prolonged growth of E. coli at high osmotic pressure. Of note, bacteria cultivated at low and high osmotic pressures had similar Q8 concentrations. The protection of respiration was neither diminished by cardiolipin deficiency nor conferred by trehalose overproduction during growth at low osmotic pressure, but rather might be achieved by Q8-independent respiratory chain remodeling. We conclude that osmotolerance is conferred through Q8-independent protection of respiration, not by altering physical properties of the membrane.

NAD+ precursor increases aerobic performance in mice.

PURPOSE: Nicotinamide riboside (NR) acts as a potent NAD+ precursor and improves mitochondrial oxidative capacity and mitochondrial biogenesis in several organisms. However, the effects of NR supplementation on aerobic performance remain unclear. Here, we evaluated the effects of NR supplementation on the muscle metabolism and aerobic capacity of sedentary and trained mice. METHODS: Male C57BL/6 J mice were supplemented with NR (400 mg/Kg/day) over 5 and 10 weeks. The training protocol consisted of 5 weeks of treadmill aerobic exercise, for 60 min a day, 5 days a week. Bioinformatic and physiological assays were combined with biochemical and molecular assays to evaluate the experimental groups. RESULTS: NR supplementation by itself did not change the aerobic performance, even though 5 weeks of NR supplementation increased NAD+ levels in the skeletal muscle. However, combining NR supplementation and aerobic training increased the aerobic performance compared to the trained group. This was accompanied by an increased protein content of NMNAT3, the rate-limiting enzyme for NAD + biosynthesis and mitochondrial proteins, including MTCO1 and ATP5a. Interestingly, the transcriptomic analysis using a large panel of isogenic strains of BXD mice confirmed that the Nmnat3 gene in the skeletal muscle is correlated with several mitochondrial markers and with different phenotypes related to physical exercise. Finally, NR supplementation during aerobic training markedly increased the amount of type I fibers in the skeletal muscle. CONCLUSION: Taken together, our results indicate that NR may be an interesting strategy to improve mitochondrial metabolism and aerobic capacity.

Teriflunomide treatment for multiple sclerosis modulates T cell mitochondrial respiration with affinity-dependent effects.

Interference with immune cell proliferation represents a successful treatment strategy in T cell-mediated autoimmune diseases such as rheumatoid arthritis and multiple sclerosis (MS). One prominent example is pharmacological inhibition of dihydroorotate dehydrogenase (DHODH), which mediates de novo pyrimidine synthesis in actively proliferating T and B lymphocytes. Within the TERIDYNAMIC clinical study, we observed that the DHODH inhibitor teriflunomide caused selective changes in T cell subset composition and T cell receptor repertoire diversity in patients with relapsing-remitting MS (RRMS). In a preclinical antigen-specific setup, DHODH inhibition preferentially suppressed the proliferation of high-affinity T cells. Mechanistically, DHODH inhibition interferes with oxidative phosphorylation (OXPHOS) and aerobic glycolysis in activated T cells via functional inhibition of complex III of the respiratory chain. The affinity-dependent effects of DHODH inhibition were closely linked to differences in T cell metabolism. High-affinity T cells preferentially use OXPHOS during early activation, which explains their increased susceptibility toward DHODH inhibition. In a mouse model of MS, DHODH inhibitory treatment resulted in preferential inhibition of high-affinity autoreactive T cell clones. Compared to T cells from healthy controls, T cells from patients with RRMS exhibited increased OXPHOS and glycolysis, which were reduced with teriflunomide treatment. Together, these data point to a mechanism of action where DHODH inhibition corrects metabolic disturbances in T cells, which primarily affects profoundly metabolically active high-affinity T cell clones. Hence, DHODH inhibition may promote recovery of an altered T cell receptor repertoire in autoimmunity.

Bouchardatine suppresses rectal cancer in mice by disrupting its metabolic pathways via activating the SIRT1-PGC-1α-UCP2 axis.

Cancer metabolism is an attractive target of the therapeutic strategy for cancer. The present study identified bouchardatine (Bou) as a potent suppressor of rectal cancer growth by cycle-arresting independent of apoptosis. In cultured HCT-116 rectal cancer cells, Bou increased glucose uptake/oxidation and capacity of mitochondrial oxidation. These effects were associated with an upregulation of uncoupling protein 2 (UCP2) and the activation of its upstream Sirtuin 1 (SIRT1)/(Liver kinase B1) LKB1- (Adenosine monophosphate-activated protein kinase) AMPK axis. The pivotal role of UCP2 in the cancer-suppressing effect was demonstrated by overexpressing UCP2 in HCT-116 cells with similar metabolic effects to those produced by Bou. Interestingly, Bou activated peroxisome proliferators activated receptor γ coactivator 1α (PGC-1α) and recruited it to the promoter of UCP2 in HCT-116 cells along with deacetylation (thus activation) by SIRT1. The requirement of SIRT1 for the cancer-suppressing effect through the PGC-1α-UCP2 was confirmed by the reciprocal responses to Bou in HCT-116 with defected and overexpressed SIRT1. Whereas knockdown, mutation or pharmacological inhibition of SIRT1 all abolished Bou-induced deacetylation/activation of PGC-1α, the opposing effects were observed after overexpressing SIRT1. In mice, administration of Bou (50 mg/kg) also suppressed the growth of rectal cancer associated with increases the UCP2 expression and mitochondria capacity in the tumor. Collectively, our findings suggest that Bou has a therapeutic potential for the treatment of rectal cancer by disrupting the metabolic path of cancer cells via activating the PGC-1α-UCP2 axis with SIRT1 as its primary target.

Liver mitochondrial respiratory plasticity and oxygen uptake evoked by cobalt chloride in rats with low and high resistance to extreme hypobaric hypoxia.

High-altitude intolerance and consequently high-altitude sickness, is difficult to predict. Liver is an essential organ in glucose and lipid metabolism, and may play key role in the adaptation to high altitude. In response to extreme high altitude, mitochondrial respiration exhibits changes in substrate metabolism, mitochondrial electron transport chain activity, and respiratory coupling. We determined the cobalt chloride (CoCl2) effects on liver mitochondrial plasticity and oxygen uptake in rats with low resistance (LR) and high resistance (HR) to extreme hypobaric hypoxia. The polarographic method proposed by Chance and Williams was used as a simple and effective tool to trace mitochondrial functionality and oxygen consumption. HR rats had more efficient processes of NADH- and FAD-generated mitochondrial oxidation. CoCl2 promoted more efficient NADH-generated and diminished less efficient FAD-generated mitochondrial respiratory reactions in HR rats. CoCl2 diminished both aerobic and anaerobic processes in LR rats. Glutamate and pyruvate substrates of NADH-generated mitochondrial pathways were highly affected by CoCl2. Red blood cells acted as cobalt depots in HR and LR rats. We have unveiled several mechanisms leading to differentiated mitochondrial respiratory responses to hypobaric hypoxia in LR and HR rats. Our study strongly supports the existence of adaptive liver mitochondrial plasticity to extreme hypoxia.