Metabolic flexibility
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Východiska: Společným rysem metabolizmu nádorových buněk je schopnost získávat potřebné živiny z poměrně chudého prostředí a využívat je k udržení životaschopnosti a tvorbě nové biomasy. Změny v intracelulárních a extracelulárních metabolitech, které doprovází metabolické přeprogramování spojené s růstem nádoru, mají následně zásadní účinek na genovou expresi, buněčnou diferenciaci a mikroprostředí nádoru. V průběhu kancerogeneze čelí nádorové buňky selekčním tlakům, které je nutí neustále optimalizovat dominantní metabolické dráhy a nádorové buňky tak procházejí zásadními metabolickými reorganizacemi. Obecně platí, že vyšší flexibilita metabolických drah zvyšuje schopnost nádorových buněk sladit metabolické potřeby s měnícím se prostředím. Cíl: V tomto přehledovém článku pojednáváme o metabolických vlastnostech nádorových buněk a popisujeme účinek transformovaného metabolizmu na progresi nádoru. Domníváme se, že metabolické změny jsou pro rozvoj nádorů zásadní a mohly by poskytnout zajímavé cíle pro léčbu.
Background: A general characteristic of cancer metabolism is the skill to gain the essential nutrients from a relatively poor environment and use them effectively to maintain viability and create new biomass. The changes in intracellular and extracellular metabolites that accompany metabolic reprogramming associated with tumor growth subsequently affect gene expression, cell differentiation, and tumor microenvironment. During carcinogenesis, cancer cells face huge selection pressures that force them to constantly optimize dominant metabolic pathways and undergo major metabolic reorganizations. In general, greater flexibility of metabolic pathways increases the ability of tumor cells to satisfy their metabolic needs in a changing environment. Purpose: In this review, we discuss the metabolic properties of cancer cells and describe the tumor promoting effect of the transformed metabolism. We assume that changes in metabolism are significant enough to facilitate tumorigenesis and may provide interesting targets for cancer therapy.
Decreased metabolic flexibility, i.e. a compromised ability to adjust fuel oxidation to fuel availability supports development of adverse consequences of obesity. The aims of this study were (i) to learn whether obesity-resistant A/J and obesity-prone C57BL/6J mice differ in their metabolic flexibility right after weaning; and (ii) to characterize possible differences in control of glucose homeostasis in these animals using glucose tolerance tests (GTT). A/J and C57BL/6J mice of both genders were maintained at 20 °C and weaned to standard low-fat diet at 30 days of age. During the first day after weaning, using several separate animal cohorts, (i) GTT was performed using 1 or 3 mg glucose/g body weight (BW), while glucose was administered either orally (OGTT) or intraperitoneally (IPGTT) at 20 °C; and (ii) indirect calorimetry (INCA) was performed, either in a combination with oral gavage of 1 or 7.5 mg glucose/g BW, or during a fasting/re-feeding transition. INCA was conducted either at 20 °C or 34 °C. Results of both OGTT and IPGTT using 1 mg glucose/g BW at 20 °C, and INCA using 7.5 mg glucose/g BW at 34 °C, indicated higher glucose tolerance and higher metabolic flexibility to glucose, respectively, and lower fasting glycemia in A/J mice as compared with C57BL/6J mice. Thus, control of whole body glucose metabolism between A/J and C57BL/6J mice represents a phenotypic feature differentiating between the strains right after weaning.
- MeSH
- druhová specificita MeSH
- glukosa * metabolismus farmakologie MeSH
- glukózový toleranční test MeSH
- myši MeSH
- obezita genetika metabolismus patologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Naegleria gruberi is a free-living amoeba, closely related to the human pathogen Naegleria fowleri, the causative agent of the deadly human disease primary amoebic meningoencephalitis. Herein, we investigated the effect of iron limitation on different aspects of N. gruberi metabolism. Iron metabolism is among the most conserved pathways found in all eukaryotes. It includes the delivery, storage and utilisation of iron in many cell processes. Nevertheless, most of the iron metabolism pathways of N. gruberi are still not characterised, even though iron balance within the cell is crucial. We found a single homolog of ferritin in the N. gruberi genome and showed its localisation in the mitochondrion. Using comparative mass spectrometry, we identified 229 upregulated and 184 down-regulated proteins under iron-limited conditions. The most down-regulated protein under iron-limited conditions was hemerythrin, and a similar effect on the expression of hemerythrin was found in N. fowleri. Among the other down-regulated proteins were [FeFe]-hydrogenase and its maturase HydG and several heme-containing proteins. The activities of [FeFe]-hydrogenase, as well as alcohol dehydrogenase, were also decreased by iron deficiency. Our results indicate that N. gruberi is able to rearrange its metabolism according to iron availability, prioritising mitochondrial pathways. We hypothesise that the mitochondrion is the center for iron homeostasis in N. gruberi, with mitochondrially localised ferritin as a potential key component of this process.
- MeSH
- anaerobióza MeSH
- biologický transport MeSH
- chromatografie kapalinová MeSH
- hemerythrin metabolismus MeSH
- hmotnostní spektrometrie MeSH
- Naegleria metabolismus MeSH
- protozoální proteiny genetika MeSH
- regulace genové exprese enzymů účinky léků MeSH
- spotřeba kyslíku MeSH
- železo metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Poly-unsaturated fatty acids (PUFAs) are considered to be healthier than saturated fatty acids (SFAs), but others postulate that especially the ratio of omega-6 to omega-3 PUFAs (n6/n3 ratio) determines health. Health can be determined with biomarkers, but functional health status is likely better reflected by challenge tests that assess metabolic flexibility. The aim of this study was to determine the effect of high-fat diets with different fatty acid compositions, but similar n6/n3 ratio, on metabolic flexibility. Therefore, adult male mice received isocaloric high-fat diets with either predominantly PUFAs (HFpu diet) or predominantly SFAs (HFs diet) but similar n6/n3 ratio for six months, during and after which several biomarkers for health were measured. Metabolic flexibility was assessed by the response to an oral glucose tolerance test, a fasting and re-feeding test and an oxygen restriction test (OxR; normobaric hypoxia). The latter two are non-invasive, indirect calorimetry-based tests that measure the adaptive capacity of the body as a whole. We found that the HFs diet, compared to the HFpu diet, increased mean adipocyte size, liver damage, and ectopic lipid storage in liver and muscle; although, we did not find differences in body weight, total adiposity, adipose tissue health, serum adipokines, whole body energy balance, or circadian rhythm between HFs and HFpu mice. HFs mice were, furthermore, less flexible in their response to both fasting- re-feeding and OxR, while glucose tolerance was indistinguishable. To conclude, the HFs versus the HFpu diet increased ectopic fat storage, liver damage, and mean adipocyte size and reduced metabolic flexibility in male mice. This study underscores the physiological relevance of indirect calorimetry-based challenge tests.
- MeSH
- adipozita MeSH
- dieta s vysokým obsahem tuků MeSH
- energetický metabolismus fyziologie MeSH
- glukózový toleranční test MeSH
- hypoxie MeSH
- játra cytologie metabolismus MeSH
- kosterní svaly metabolismus MeSH
- kyseliny mastné omega-6 metabolismus MeSH
- metabolismus lipidů MeSH
- mitochondrie fyziologie MeSH
- myši inbrední C57BL MeSH
- myši transgenní MeSH
- myši MeSH
- omega-3 mastné kyseliny metabolismus MeSH
- tuková tkáň metabolismus MeSH
- tukové buňky metabolismus MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Insulin resistance, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. This, in turn, contributes to a further damage of insulin signaling. Effectiveness of T2D treatment depends in large part on the improvement of insulin sensitivity and metabolic adaptability of the muscle, the main site of whole-body glucose utilization. We have shown previously in mice fed an obesogenic high-fat diet that a combined use of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinediones (TZDs), anti-diabetic drugs, preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether n-3 LC-PUFA could elicit additive beneficial effects on metabolic flexibility when combined with a TZD drug rosiglitazone. Adult male C57BL/6N mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various interventions: cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids (cHF+F), cHF with 10 mg rosiglitazone/kg diet (cHF+ROSI), cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combined intervention. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the interventions, with n-3 LC-PUFA supporting complete oxidation of fatty acids in mitochondria and the combination with n-3 LC-PUFA and rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combined use of n-3 LC-PUFA and TZDs could improve the efficacy of the therapy of obese and diabetic patients.
- MeSH
- dieta s vysokým obsahem tuků škodlivé účinky MeSH
- glykolýza účinky léků MeSH
- kosterní svalová vlákna účinky léků metabolismus MeSH
- kosterní svaly účinky léků metabolismus MeSH
- metabolomika MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- obezita etiologie metabolismus MeSH
- omega-3 mastné kyseliny farmakologie MeSH
- oxidace-redukce účinky léků MeSH
- regulace genové exprese účinky léků MeSH
- synergismus léků MeSH
- thiazolidindiony farmakologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Nitrite-oxidizing bacteria (NOB) are ubiquitous and abundant microorganisms that play key roles in global nitrogen and carbon biogeochemical cycling. Despite recent advances in understanding NOB physiology and taxonomy, currently very few cultured NOB or representative NOB genome sequences from marine environments exist. In this study, we employed enrichment culturing and genomic approaches to shed light on the phylogeny and metabolic capacity of marine NOB. We successfully enriched two marine NOB (designated MSP and DJ) and obtained a high-quality metagenome-assembled genome (MAG) from each organism. The maximum nitrite oxidation rates of the MSP and DJ enrichment cultures were 13.8 and 30.0 μM nitrite per day, respectively, with these optimum rates occurring at 0.1 mM and 0.3 mM nitrite, respectively. Each enrichment culture exhibited a different tolerance to various nitrite and salt concentrations. Based on phylogenomic position and overall genome relatedness indices, both NOB MAGs were proposed as novel taxa within the Nitrospinota and Nitrospirota phyla. Functional predictions indicated that both NOB MAGs shared many highly conserved metabolic features with other NOB. Both NOB MAGs encoded proteins for hydrogen and organic compound metabolism and defense mechanisms for oxidative stress. Additionally, these organisms may have the genetic potential to produce cobalamin (an essential enzyme cofactor that is limiting in many environments) and, thus, may play an important role in recycling cobalamin in marine sediment. Overall, this study appreciably expands our understanding of the Nitrospinota and Nitrospirota phyla and suggests that these NOB play important biogeochemical roles in marine habitats.IMPORTANCE Nitrification is a key process in the biogeochemical and global nitrogen cycle. Nitrite-oxidizing bacteria (NOB) perform the second step of aerobic nitrification (converting nitrite to nitrate), which is critical for transferring nitrogen to other organisms for assimilation or energy. Despite their ecological importance, there are few cultured or genomic representatives from marine systems. Here, we obtained two NOB (designated MSP and DJ) enriched from marine sediments and estimated the physiological and genomic traits of these marine microbes. Both NOB enrichment cultures exhibit distinct responses to various nitrite and salt concentrations. Genomic analyses suggest that these NOB are metabolically flexible (similar to other previously described NOB) yet also have individual genomic differences that likely support distinct niche distribution. In conclusion, this study provides more insights into the ecological roles of NOB in marine environments.
- MeSH
- Bacteria klasifikace izolace a purifikace metabolismus MeSH
- dusitany metabolismus MeSH
- geologické sedimenty mikrobiologie MeSH
- metabolické sítě a dráhy MeSH
- mikrobiota * MeSH
- mořská voda mikrobiologie MeSH
- oxidace-redukce MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Korejská republika MeSH
Human cytochrome P450 2D6 (CYP2D6) is an enzyme of the CYP superfamily responsible for biotransformation of about 20% of drugs of known metabolism containing a basic nitrogen and a planar aromatic ring. Here, we present a combined experimental and computational study on the compressibility and flexibility of unliganded and quinidine-bound CYP2D6. Experimentally, high-pressure induced Soret band shifts of the enzyme were measured by UV/VIS spectroscopy, while 100 ns all atomic molecular dynamics (MD) simulations in explicit water were used in the computational analysis. We identified sharp differences between ligand-free and quinidine-bound CYP2D6 forms in compressibility, flexibility parameters and active site solvation. While the unliganded CYP2D6 is compressible, quinidine binding significantly rigidifies the CYP2D6 active site. In addition, MD simulations show that quinidine binding results in pronounced reductions in active site flexibility and solvation.
Celosvětově narůstá výskyt obezity a diabetes mellitus 2. typu. Situace nabývá charakteru pandemie a představuje významný medicínsko-ekonomický problém. Pozornost, která byla a je v této souvislosti věnována tukové tkáni, vedla k posunu představ o jejím významu pro organismus. Ukázalo se, že zdaleka nejde jen o energetickou zásobárnu zajišťující tepelnou a mechanickou izolaci ostatních orgánů a organismu. Byla odhalena řada významných fyziologických funkcí v látkové přeměně a hormonálních interakcích s ostatními tkáněmi zúčastněných v intermediálním metabolismu i mimo něj. Metabolická flexibilita tukové tkáně je významnou ochranou před nežádoucími účinky nadměrného energetického přívodu. Po přesáhnutí její fyziologické kapacity se však stává spolupodílníkem na rozvoji inzulínové rezistence, oxidačního stresu a dalších odchylek vedoucích ve svém důsledku k urychlení aterosklerotického procesu a zvýšené kardiovaskulární morbiditě a mortalitě. Na fyziologických a patologických funkcích tukové tkáně se nepodílejí jen adipocyty, ale též další její složky, například stromální buňky a cévní systém. Adekvátní regulace cévního zásobení umožňuje komunikaci tukové tkáně s dalšími systémy a reagování na energetický stav organismu. Změny krevního průtoku tukovou tkání se vyvíjejí od časných stadií obezity a spolupodílí se na prohlubování nepříznivých odchylek intermediálního metabolismu.
Worldwide growth of obesity and prevalence of type 2 diabetes mellitus reach the extent of a pandemy and represent a considerable medical and economic problem. An attention devoted to adipose tissue has led to the shift in general perception of its importance. It becomes evident that adipose tissue is not by far only an energy store with thermal and mechanical protection of other organs and body. A number of important functions in intermediary metabolism and hormonal interactions with other tissues have been disclosed. Metabolic flexibility of adipose tissue represents an essential protection against undesirable effects of excessive energy intake. Nevertheless, after exceeding of its physiological capacity adipose tissue becomes an important cause of insulin resistance, oxidative stress and a number of other derangements leading to atherosclerosis progression and increase of cardiovascular morbidity and mortality. Not only adipocytes but also stromal cells and vascular bed participate in the physiological and pathological functions of adipose tissue. Adequate regulation of adipose tissue blood flow ensures communication with other systems and appropriate reactions to energy needs of the organism. Disturbances in adipose tissue blood flow evolve at early stages of obesity and participate in the worsening of metabolic syndrome.
To gain more complete insight into flexibility and malleability of five forms of human liver cytochrome P450 enzymes, which play major roles in drug metabolism (CYPs 1A2, 2A6, 2C9, 2D6 and 3A4), we employed UV/VIS and resonance Raman spectroscopy in combination with all-atomic molecular dynamics simulations under normal and high pressure conditions (300 MPa). In general, the high pressure reduces the flexibility of CYPs, which become more dense and compact as their radii of gyration and temperature B-factors diminish. The flexibility of CYPs spans the regions, which are localized in solvent exposed loops. A considerable degree of flexibility is also observed at amino-acids making the pw2 and solvent channels, which are suggested to serve for substrate access and/or product release. The number of water molecules as well as the number of protein backbone atoms of the active site in close proximity of heme cofactor generally increases under high pressure. This finding provides new insights regarding the interpretation of pressure-related Soret band red shifts. Presented results also point towards considerable differences between the CYP forms studied: CYP2A6 and CYP1A2 have the least malleable active sites while those of CYP2D6, CYP2C9 and CYP3A4 have considerably greater degrees of flexibility or malleability. In addition, the number of water molecules in the active site cavity of CYP3A4 anomalously decreases under high pressure due to opening of the active site. These results correlate with the known substrate promiscuity of the respective CYP forms, with CYP3A4 displaying the highest substrate promiscuity, corresponding to the most open and malleable active site, whereas CYP1A2 and CYP2A6 show a high substrate-specificity and have a small and rigid active sites.
- MeSH
- aromatické hydroxylasy chemie metabolismus MeSH
- cytochrom P-450 CYP1A2 chemie metabolismus MeSH
- cytochrom P-450 CYP2D6 chemie metabolismus MeSH
- cytochrom P-450 CYP3A chemie metabolismus MeSH
- hem chemie metabolismus MeSH
- hydrostatický tlak MeSH
- izoenzymy chemie metabolismus MeSH
- játra enzymologie MeSH
- katalytická doména MeSH
- konformace proteinů MeSH
- lidé MeSH
- molekulární modely MeSH
- Ramanova spektroskopie MeSH
- simulace molekulární dynamiky MeSH
- spektrofotometrie metody MeSH
- substrátová specifita MeSH
- systém (enzymů) cytochromů P-450 chemie metabolismus MeSH
- terciární struktura proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
