3-methylglutaconic aciduria (3-MGCA) is a biochemical finding in a diverse group of inherited metabolic disorders. Conditions manifesting 3-MGCA are classified into two major categories, primary and secondary. Primary 3-MGCAs involve two inherited enzymatic deficiencies affecting leucine catabolism, whereas secondary 3-MGCAs comprise a larger heterogeneous group of conditions that have in common compromised mitochondrial energy metabolism. Here, we report 3-MGCA in two siblings presenting with sensorineural hearing loss and neurological abnormalities associated with a novel, homozygous missense variant (c.1999C>G, p.Leu667Val) in the YME1L1 gene which encodes a mitochondrial ATP-dependent metalloprotease. We show that the identified variant results in compromised YME1L1 function, as evidenced by abnormal proteolytic processing of substrate proteins, such as OPA1 and PRELID1. Consistent with the aberrant processing of the mitochondrial fusion protein OPA1, we demonstrate enhanced mitochondrial fission and fragmentation of the mitochondrial network in patient-derived fibroblasts. Furthermore, our results indicate that YME1L1L667V is associated with attenuated activity of rate-limiting Krebs cycle enzymes and reduced mitochondrial respiration, which may explain the build-up of 3-methylglutaconic and 3-methylglutaric acid due to the diversion of acetyl-CoA, not efficiently processed in the Krebs cycle, towards the formation of 3-methylglutaconyl-CoA, the precursor of these metabolites. In summary, our findings classify YME1L1 deficiency as a new type of secondary 3-MGCA, thus expanding the genetic landscape and facilitating the diagnosis of inherited metabolic disorders featuring this biochemical phenotype.

• MeSH
• dítě MeSH
• fibroblasty metabolismus   MeSH
• glutaráty MeSH
• lidé MeSH
• metaloendopeptidasy * genetika   metabolismus   MeSH
• missense mutace MeSH
• mitochondriální dynamika MeSH
• mitochondriální proteiny * genetika   MeSH
• mitochondrie metabolismus   MeSH
• percepční nedoslýchavost genetika   MeSH
• sourozenci MeSH
• vrozené poruchy metabolismu * genetika   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

BACKGROUND: The human mitochondrial alpha-ketoglutarate dehydrogenase complex (hKGDHc) converts KG to succinyl-CoA and NADH. Malfunction of and reactive oxygen species generation by the hKGDHc as well as its E1-E2 subcomplex are implicated in neurodegenerative disorders, ischemia-reperfusion injury, E3-deficiency and cancers. METHODS: We performed cryo-EM, cross-linking mass spectrometry (CL-MS) and molecular modeling analyses to determine the structure of the E2 component of the hKGDHc (hE2k); hE2k transfers a succinyl group to CoA and forms the structural core of hKGDHc. We also assessed the overall structure of the hKGDHc by negative-stain EM and modeling. RESULTS: We report the 2.9 Å resolution cryo-EM structure of the hE2k component. The cryo-EM map comprises density for hE2k residues 151-386 - the entire (inner) core catalytic domain plus a few additional residues -, while residues 1-150 are not observed due to the inherent flexibility of the N-terminal region. The structure of the latter segment was also determined by CL-MS and homology modeling. Negative-stain EM on in vitro assembled hKGDHc and previous data were used to build a putative overall structural model of the hKGDHc. CONCLUSIONS: The E2 core of the hKGDHc is composed of 24 hE2k chains organized in octahedral (8 × 3 type) assembly. Each lipoyl domain is oriented towards the core domain of an adjacent chain in the hE2k homotrimer. hE1k and hE3 are most likely tethered at the edges and faces, respectively, of the cubic hE2k assembly. GENERAL SIGNIFICANCE: The revealed structural information will support the future pharmacologically targeting of the hKGDHc.

• MeSH
• acylkoenzym A metabolismus   MeSH
• acyltransferasy chemie   metabolismus   MeSH
• elektronová kryomikroskopie metody   MeSH
• hmotnostní spektrometrie metody   MeSH
• ketoglutarátdehydrogenasový komplex chemie   metabolismus   MeSH
• konformace proteinů MeSH
• kyseliny ketoglutarové metabolismus   MeSH
• lidé MeSH
• molekulární modely MeSH
• NAD metabolismus   MeSH
• reagencia zkříženě vázaná chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) are increased in starvation and diabetes mellitus. However, the pathogenesis has not been explained. It has been shown that BCAA catabolism occurs mostly in muscles due to high activity of BCAA aminotransferase, which converts BCAA and α-ketoglutarate (α-KG) to branched-chain keto acids (BCKAs) and glutamate. The loss of α-KG from the citric cycle (cataplerosis) is attenuated by glutamate conversion to α-KG in alanine aminotransferase and aspartate aminotransferase reactions, in which glycolysis is the main source of amino group acceptors, pyruvate and oxaloacetate. Irreversible oxidation of BCKA by BCKA dehydrogenase is sensitive to BCKA supply, and ratios of NADH to NAD+ and acyl-CoA to CoA-SH. It is hypothesized that decreased glycolysis and increased fatty acid oxidation, characteristic features of starvation and diabetes, cause in muscles alterations resulting in increased BCAA levels. The main alterations include (i) impaired BCAA transamination due to decreased supply of amino groups acceptors (α-KG, pyruvate, and oxaloacetate) and (ii) inhibitory influence of NADH and acyl-CoAs produced in fatty acid oxidation on citric cycle and BCKA dehydrogenase. The studies supporting the hypothesis and pros and cons of elevated BCAA concentrations are discussed in the article.

• MeSH
• alanin metabolismus   MeSH
• diabetes mellitus metabolismus   MeSH
• glykolýza MeSH
• hladovění metabolismus   MeSH
• inzulin metabolismus   MeSH
• inzulinová rezistence MeSH
• kyseliny ketoglutarové metabolismus   MeSH
• lidé MeSH
• mastné kyseliny metabolismus   MeSH
• obezita metabolismus   MeSH
• oxidace-redukce MeSH
• pyruváty farmakokinetika   MeSH
• svaly enzymologie   metabolismus   MeSH
• transaminasy metabolismus   MeSH
• větvené aminokyseliny metabolismus   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Wild type mitochondrial isocitrate dehydrogenase (IDH2) was previously reported to produce oncometabolite 2-hydroxyglutarate (2HG). Besides, mitochondrial deacetylase SIRT3 has been shown to regulate the oxidative function of IDH2. However, regulation of 2HG formation by SIRT3-mediated deacetylation was not investigated yet. We aimed to study mitochondrial IDH2 function in response to acetylation and deacetylation, and focus specifically on 2HG production by IDH2. We used acetylation surrogate mutant of IDH2 K413Q and assayed enzyme kinetics of oxidative decarboxylation of isocitrate, 2HG production by the enzyme, and 2HG production in cells. The purified IDH2 K413Q exhibited lower oxidative reaction rates than IDH2 WT. 2HG production by IDH2 K413Q was largely diminished at the enzymatic and cellular level, and knockdown of SIRT3 also inhibited 2HG production by IDH2. Contrary, the expression of putative mitochondrial acetylase GCN5L likely does not target IDH2. Using mass spectroscopy, we further identified lysine residues within IDH2, which are the substrates of SIRT3. In summary, we demonstrate that 2HG levels arise from non-mutant IDH2 reductive function and decrease with increasing acetylation level. The newly identified lysine residues might apply in regulation of IDH2 function in response to metabolic perturbations occurring in cancer cells, such as glucose-free conditions.

• MeSH
• acetylace MeSH
• glutaráty metabolismus   MeSH
• isocitrátdehydrogenasa genetika   metabolismus   MeSH
• isocitráty chemie   MeSH
• lidé MeSH
• mitochondrie metabolismus   MeSH
• nádorové buněčné linie MeSH
• NADP metabolismus   MeSH
• oxidace-redukce MeSH
• proteiny nervové tkáně metabolismus   MeSH
• sirtuin 3 metabolismus   MeSH
• umlčování genů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Significance: Cancer cells are stabilized in an undifferentiated state similar to stem cells. This leads to profound modifications of their metabolism, which further modifies their genetics and epigenetics as malignancy progresses. Specific metabolites and enzymes may serve as clinical markers of cancer progression. Recent Advances: Both 2-hydroxyglutarate (2HG) enantiomers are associated with reprogrammed metabolism, in grade III/IV glioma, glioblastoma, and acute myeloid leukemia cells, and numerous other cancer types, while acting also in the cross talk of tumors with immune cells. 2HG contributes to specific alternations in cancer metabolism and developed oxidative stress, while also inducing decisions on the differentiation of naive T lymphocytes, and serves as a signal messenger in immune cells. Moreover, 2HG inhibits chromatin-modifying enzymes, namely 2-oxoglutarate-dependent dioxygenases, and interferes with hypoxia-inducible factor (HIF) transcriptome reprogramming and mammalian target of rapamycin (mTOR) pathway, thus dysregulating gene expression and further promoting cancerogenesis. Critical Issues: Typically, heterozygous mutations within the active sites of isocitrate dehydrogenase isoform 1 (IDH1)R132H and mitochondrial isocitrate dehydrogenase isoform 2 (IDH2)R140Q provide cells with millimolar r-2-hydroxyglutarate (r-2HG) concentrations, whereas side activities of lactate and malate dehydrogenase form submillimolar s-2-hydroxyglutarate (s-2HG). However, even wild-type IDH1 and IDH2, notably under shifts toward reductive carboxylation glutaminolysis or changes in other enzymes, lead to "intermediate" 0.01-0.1 mM 2HG levels, for example, in breast carcinoma compared with 10-8M in noncancer cells. Future Directions: Uncovering further molecular metabolism details specific for given cancer cell types and sequence-specific epigenetic alternations will lead to the design of diagnostic approaches, not only for predicting patients' prognosis or uncovering metastases and tumor remissions but also for early diagnostics.

• MeSH
• energetický metabolismus MeSH
• epigeneze genetická MeSH
• glutaráty metabolismus   MeSH
• imunomodulace MeSH
• isocitrátdehydrogenasa genetika   metabolismus   MeSH
• lidé MeSH
• mutace MeSH
• náchylnost k nemoci * MeSH
• nádorové kmenové buňky metabolismus   MeSH
• nádory etiologie   metabolismus   patologie   MeSH
• oxidace-redukce MeSH
• progrese nemoci MeSH
• regulace genové exprese u nádorů MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The unique capability of proton buffering is the rationale for using histidine (HIS) as a component of solutions for induction of cardiac arrest and myocardial protection in cardiac surgery. In humans, infusion of cardioplegic solution may increase blood plasma HIS from ~ 70 to ~ 21,000 µM. We examined the effects of a large intravenous dose of HIS on ammonia and amino acid concentrations and energy status of the body. Rats received 198 mM HIS intravenously (20 ml/kg) or vehicle. Samples of blood plasma, urine, liver, and soleus (SOL) and extensor digitorum longus (EDL) muscles were analysed at 2 or 24 h after treatment. At 2 h after HIS load, we found higher HIS concentration in all examined tissues, higher urea and ammonia concentrations in blood and urine, lower ATP content and higher AMP/ATP ratio in the liver and muscles, higher concentrations of almost all examined amino acids in urine, and lower glycine concentration in blood plasma, liver, and muscles when compared with controls. Changes in other amino acids were tissue dependent, markedly increased alanine and glutamate in the blood and the liver. At 24 h, the main findings were lower ATP concentrations in muscles, lower concentrations of branched-chain amino acids (BCAA; valine, leucine, and isoleucine) in blood plasma and muscles, and higher carnosine content in SOL when compared with controls. It is concluded that a load of large HIS dose results in increased ammonia levels and marked alterations in amino acid and energy metabolism. Pathogenesis is discussed in the article.

• MeSH
• adeninnukleotidy metabolismus   MeSH
• aminokyseliny chemie   metabolismus   MeSH
• amoniak metabolismus   MeSH
• energetický metabolismus MeSH
• histidin aplikace a dávkování   analýza   metabolismus   MeSH
• intravenózní podání MeSH
• kardioplegické roztoky chemie   MeSH
• karnosin metabolismus   MeSH
• krysa rodu rattus MeSH
• kyseliny ketoglutarové metabolismus   MeSH
• močovina metabolismus   MeSH
• orgánová specificita MeSH
• potkani Wistar MeSH
• tkáňová distribuce MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The patients with mantle cell lymphoma (MCL) have translocation t(11;14) associated with cyclin D1 overexpression. We observed that iron (an essential cofactor of dioxygenases including prolyl hydroxylases [PHDs]) depletion by deferoxamine blocked MCL cells' proliferation, increased expression of DNA damage marker γH2AX, induced cell cycle arrest and decreased cyclin D1 level. Treatment of MCL cell lines with dimethyloxalylglycine, which blocks dioxygenases involving PHDs by competing with their substrate 2-oxoglutarate, leads to their decreased proliferation and the decrease of cyclin D1 level. We then postulated that loss of EGLN2/PHD1 in MCL cells may lead to down-regulation of cyclin D1 by blocking the degradation of FOXO3A, a cyclin D1 suppressor. However, the CRISPR/Cas9-based loss-of-function of EGLN2/PHD1 did not affect cyclin D1 expression and the loss of FOXO3A did not restore cyclin D1 levels after iron chelation. These data suggest that expression of cyclin D1 in MCL is not controlled by ENGL2/PHD1-FOXO3A pathway and that chelation- and 2-oxoglutarate competition-mediated down-regulation of cyclin D1 in MCL cells is driven by yet unknown mechanism involving iron- and 2-oxoglutarate-dependent dioxygenases other than PHD1. These data support further exploration of the use of iron chelation and 2-oxoglutarate-dependent dioxygenase inhibitors as a novel therapy of MCL.

• MeSH
• aminokyseliny dikarboxylové farmakologie   MeSH
• chelátory železa farmakologie   MeSH
• cyklin D1 metabolismus   MeSH
• deferoxamin farmakologie   MeSH
• deficit železa MeSH
• dioxygenasy antagonisté a inhibitory   metabolismus   MeSH
• down regulace účinky léků   MeSH
• hydroxylace MeSH
• hypoxie buňky účinky léků   MeSH
• inhibitory enzymů farmakologie   MeSH
• kyseliny ketoglutarové farmakologie   MeSH
• lidé MeSH
• lymfom z plášťových buněk enzymologie   MeSH
• messenger RNA genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• poškození DNA MeSH
• prolyl-4-hydroxylasy HIF metabolismus   MeSH
• protein FOXO3 genetika   metabolismus   MeSH
• železo MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Hypoxia causes mitochondrial cristae widening, enabled by the ~20% degradation of Mic60/mitofilin, with concomitant clustering of the MICOS complex, reflecting the widening of crista junctions (outlets) (Plecitá-Hlavatá et al. FASEB J., 2016 30:1941-1957). Attempting to accelerate metabolism by the addition of membrane-permeant dimethyl-2-oxoglutarate (dm2OG) to HepG2 cells pre-adapted to hypoxia, we found cristae narrowing by transmission electron microscopy. Glycolytic HepG2 cells, which downregulate hypoxic respiration, instantly increased respiration with dm2OG. Changes in intracristal space (ICS) morphology were also revealed by 3D super-resolution microscopy using Eos-conjugated ICS-located lactamase-β. Cristae topology was resolved in detail by focused-ion beam/scanning electron microscopy (FIB/SEM). The spatial relocations of key cristae-shaping proteins were indicated by immunocytochemical stochastic 3D super-resolution microscopy (dSTORM), while analyzing inter-antibody-distance histograms: i) ATP-synthase dimers exhibited a higher fraction of shorter inter-distances between bound F1-α primary Alexa-Fluor-647-conjugated antibodies, indicating cristae narrowing. ii) Mic60/mitofilin clusters (established upon hypoxia) decayed, restoring isotropic random Mic60/mitofilin distribution (a signature of normoxia). iii) outer membrane SAMM50 formed more focused clusters. Less abundant fractions of higher ATP-synthase oligomers of hypoxic samples on blue-native electrophoresis became more abundant fractions at the high dm2OG load and at normoxia. This indicates more labile ATP-synthase dimeric rows established at crista rims upon hypoxia, strengthened at normoxia or dm2OG-substrate load. Hypothetically, the increased Krebs substrate load stimulates the cross-linking/strengthening of rows of ATP-synthase dimers at the crista rims, making them sharper. Crista narrowing ensures a more efficient coupling of proton pumping to ATP synthesis. We demonstrated that cristae morphology changes even within minutes.

• MeSH
• buněčné dýchání MeSH
• buňky Hep G2 MeSH
• dimerizace MeSH
• hypoxie MeSH
• kyseliny ketoglutarové farmakologie   MeSH
• lidé MeSH
• mitochondriální membrány účinky léků   ultrastruktura   MeSH
• mitochondriální proteiny metabolismus   MeSH
• mitochondriální protonové ATPasy metabolismus   MeSH
• mitochondrie ultrastruktura   MeSH
• transmisní elektronová mikroskopie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The aim of the study was to screen Yarrowia lipolytica strains for keto acid production and determine optimal conditions for pyruvic acid biosynthesis from glycerol by the best producer. The analyzed parameters were thiamine concentration, medium pH, stirring speed, and substrate concentration. The screening was performed in flask cultures, whereas pyruvic acid production was carried out in 5-L stirred-tank reactor with 2 L of working volume. In total, 24 Y. lipolytica strains were compared for their abilities to produce pyruvic and α-ketoglutaric acids. The total concentration of both acids ranged from 0.1 to 15.03 g/L. Ten strains were selected for keto acid biosynthesis in bioreactor. The Y. lipolytica SKO 6 strain was identified as the best producer of pyruvic acid. In the selected conditions (thiamine concentration 1.5 μg/L, pH 4.0, stirring speed 800 rpm, 150 g/L of glycerol), the strain Y. lipolytica SKO 6 produced 99.3 g/L of pyruvic acid, with process yield of 0.63 g/g and volumetric production rate of 1.18 g/L/h. Higher titer of pyruvic acid was obtained during fed-batch culture with 200 g/L of glycerol, reaching 125.8 g/L from pure glycerol (yield 0.68 g/g) and 124.4 g/L from crude glycerol (yield 0.62 g/g). Results obtained for the strain Y. lipolytica SKO 6 proved the suitability of microbial production of pyruvic acid at industrial scale.

• MeSH
• bioreaktory MeSH
• glycerol analýza   metabolismus   MeSH
• kultivační média chemie   MeSH
• kyselina pyrohroznová analýza   metabolismus   MeSH
• kyseliny ketoglutarové analýza   metabolismus   MeSH
• techniky vsádkové kultivace MeSH
• thiamin analýza   MeSH
• Yarrowia růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

The aim was to determine the effects of enhanced availability of branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) on ammonia detoxification to glutamine (GLN) and protein metabolism in two types of skeletal muscle under hyperammonemic conditions. Isolated soleus (SOL, slow-twitch) and extensor digitorum longus (EDL, fast-twitch) muscles from the left leg of white rats were incubated in a medium with 1 mM ammonia (NH3 group), BCAAs at four times the concentration of the controls (BCAA group) or high levels of both ammonia and BCAA (NH3 + BCAA group). The muscles from the right leg were incubated in basal medium and served as paired controls. L-[1-14C]leucine was used to estimate protein synthesis and leucine oxidation, and 3-methylhistidine release was used to evaluate myofibrillar protein breakdown. We observed decreased protein synthesis and glutamate and α-ketoglutarate (α-KG) levels and increased leucine oxidation, GLN levels, and GLN release into medium in muscles in NH3 group. Increased leucine oxidation, release of branched-chain keto acids and GLN into incubation medium, and protein synthesis in EDL were observed in muscles in the BCAA group. The addition of BCAAs to medium eliminated the adverse effects of ammonia on protein synthesis and adjusted the decrease in α-KG found in the NH3 group. We conclude that (i) high levels of ammonia impair protein synthesis, activate BCAA catabolism, enhance GLN synthesis, and decrease glutamate and α-KG levels and (ii) increased BCAA availability enhances GLN release from muscles and attenuates the adverse effects of ammonia on protein synthesis and decrease in α-KG.

• MeSH
• amoniak otrava   MeSH
• citrátový cyklus účinky léků   MeSH
• glutamin agonisté   metabolismus   MeSH
• hyperamonemie enzymologie   metabolismus   patofyziologie   MeSH
• jaterní cirhóza etiologie   metabolismus   MeSH
• kyseliny ketoglutarové metabolismus   MeSH
• methylhistidiny metabolismus   MeSH
• orgánová specificita MeSH
• osmolární koncentrace MeSH
• oxidace-redukce MeSH
• potkani Wistar MeSH
• proteolýza účinky léků   MeSH
• proteosyntéza účinky léků   MeSH
• radioizotopy uhlíku MeSH
• svalová vlákna typu I účinky léků   enzymologie   metabolismus   MeSH
• svalová vlákna typu II účinky léků   enzymologie   metabolismus   MeSH
• svalové proteiny genetika   metabolismus   MeSH
• techniky in vitro MeSH
• větvené aminokyseliny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH