scholarly journals Achromobacter denitrificansStrain YD35 Pyruvate Dehydrogenase Controls NADH Production To Allow Tolerance to Extremely High Nitrite Levels

2014 ◽  
Vol 80 (6) ◽  
pp. 1910-1918 ◽  
Author(s):  
Yuki Doi ◽  
Motoyuki Shimizu ◽  
Tomoya Fujita ◽  
Akira Nakamura ◽  
Noboru Takizawa ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Pyruvate Dehydrogenase ◽  
Tca Cycle ◽  
Acetate Metabolism ◽  
Aconitate Hydratase ◽  
Acetyl Coenzyme A ◽  
Atp Level ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Antioxidant Proteins

ABSTRACTWe identified the extremely nitrite-tolerant bacteriumAchromobacter denitrificansYD35 that can grow in complex medium containing 100 mM nitrite (NO2−) under aerobic conditions. Nitrite induced global proteomic changes and upregulated tricarboxylate (TCA) cycle enzymes as well as antioxidant proteins in YD35. Transposon mutagenesis generated NO2−-hypersensitive mutants of YD35 that had mutations at genes for aconitate hydratase and α-ketoglutarate dehydrogenase in the TCA cycle and a pyruvate dehydrogenase (Pdh) E1 component, indicating the importance of TCA cycle metabolism to NO2−tolerance. A mutant in which thepdhgene cluster was disrupted (Δpdhmutant) could not grow in the presence of 100 mM NO2−. Nitrite decreased the cellular NADH/NAD+ratio and the cellular ATP level. These defects were more severe in the Δpdhmutant, indicating that Pdh contributes to upregulating cellular NADH and ATP and NO2−-tolerant growth. Exogenous acetate, which generates acetyl coenzyme A and then is metabolized by the TCA cycle, compensated for these defects caused by disruption of thepdhgene cluster and those caused by NO2−. These findings demonstrate a link between NO2−tolerance and pyruvate/acetate metabolism through the TCA cycle. The TCA cycle mechanism in YD35 enhances NADH production, and we consider that this contributes to a novel NO2−-tolerating mechanism in this strain.

Metabolism of glycolic acid by Azotobacter chroococcum PRL H62

1973 ◽  
Vol 19 (3) ◽  
pp. 321-324 ◽  
Author(s):  
W. G. W. Kurz ◽  
T. A. G. LaRue
Keyword(s):  
Nitrogen Fixation ◽  
Dicarboxylic Acid ◽  
Glycolic Acid ◽  
Tca Cycle ◽  
Azotobacter Chroococcum ◽  
Acid Cycle ◽  
Isocitric Dehydrogenase ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Reduced Nitrogen

When Azotobacter chroococcum grows on glycolic acid as sole C source, it cannot utilize N2 and must be provided with reduced nitrogen. Glycolic acid is metabolized via Kornberg's dicarboxylic acid cycle. The TCA cycle enzymes are low in activity, and isocitric dehydrogenase is absent. It is likely that isocitric dehydrogenase is the source of reductant for nitrogen fixation by Azotobacter nitrogenase.

Effect of thermal injury on the TCA cycle enzymes of Staphylococcus aureus MF 31 and Salmonella typhimurium 7136

1971 ◽  
Vol 17 (6) ◽  
pp. 759-765 ◽  
Author(s):  
Richard I. Tomlins ◽  
Merle D. Pierson ◽  
Z. John Ordal
Keyword(s):  
Lactate Dehydrogenase ◽  
Malate Dehydrogenase ◽  
Thermal Injury ◽  
Specific Activity ◽  
Fumarate Hydratase ◽  
Tca Cycle ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Oxoglutarate Dehydrogenase ◽  
Metabolic Activities

The heating of S. aureus MF-31 and S. typhimurium 7136 at 52C and 48C respectively, produced a sublethal heat injury. When injured cells were placed in fresh growth medium they recovered. The recovery of S. aureus was not inhibited by chloramphenicol. The metabolic activities of tricarboxylic acid (TCA) cycle enzymes, as well as other selected enzymes in crude extracts of normal and heat-injured cells of both microorganisms were assayed. In extracts from S. typhimurium there was some loss of specific activity with fumarate hydratase, glutamate dehydrogenase, fructose diphosphate aldolase, lactate dehydrogenase, and the NAD(P) oxidases as a result of heating. In extracts from S. aureus oxoglutarate dehydrogenase, malate dehydrogenase and lactate dehydrogenase were severely inactivated after heating. Other enzymes in comparison were only moderately sensitive to heat. No significant increase in enzyme activity was observed in extracts from injured cells of either microorganism. Re-naturation of lactate dehydrogenase and malate dehydrogenase occurred during the recovery of S. aureus both in the presence and absence of chloramphenicol. No renaturation of oxoglutarate dehydrogenase was found under the same conditions.

scholarly journals Targeting Altered Energy Metabolism in Colorectal Cancer: Oncogenic Reprogramming, the Central Role of the TCA Cycle and Therapeutic Opportunities

Cancers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1731 ◽  
Author(s):  
Carina Neitzel ◽  
Philipp Demuth ◽  
Simon Wittmann ◽  
Jörg Fahrer
Keyword(s):  
Colorectal Cancer ◽  
Energy Metabolism ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Tca Cycle ◽  
Dietary Factors ◽  
Pyruvate Dehydrogenase Kinase ◽  
Driver Mutations ◽  
The Tca Cycle

Colorectal cancer (CRC) is among the most frequent cancer entities worldwide. Multiple factors are causally associated with CRC development, such as genetic and epigenetic alterations, inflammatory bowel disease, lifestyle and dietary factors. During malignant transformation, the cellular energy metabolism is reprogrammed in order to promote cancer cell growth and proliferation. In this review, we first describe the main alterations of the energy metabolism found in CRC, revealing the critical impact of oncogenic signaling and driver mutations in key metabolic enzymes. Then, the central role of mitochondria and the tricarboxylic acid (TCA) cycle in this process is highlighted, also considering the metabolic crosstalk between tumor and stromal cells in the tumor microenvironment. The identified cancer-specific metabolic transformations provided new therapeutic targets for the development of small molecule inhibitors. Promising agents are in clinical trials and are directed against enzymes of the TCA cycle, including isocitrate dehydrogenase, pyruvate dehydrogenase kinase, pyruvate dehydrogenase complex (PDC) and α-ketoglutarate dehydrogenase (KGDH). Finally, we focus on the α-lipoic acid derivative CPI-613, an inhibitor of both PDC and KGDH, and delineate its anti-tumor effects for targeted therapy.

scholarly journals Regulation of acetate metabolism and coordination with the TCA cycle via a processed small RNA

2018 ◽  
Vol 116 (3) ◽  
pp. 1043-1052 ◽  
Author(s):  
François De Mets ◽  
Laurence Van Melderen ◽  
Susan Gottesman
Keyword(s):  
Small Rna ◽  
Posttranscriptional Regulation ◽  
Tca Cycle ◽  
Central Carbon Metabolism ◽  
Growth Defect ◽  
Acetate Metabolism ◽  
Overflow Metabolism ◽  
Acetyl Phosphate ◽  
Rnase E ◽  
The Tca Cycle

Bacterial regulatory small RNAs act as crucial regulators in central carbon metabolism by modulating translation initiation and degradation of target mRNAs in metabolic pathways. Here, we demonstrate that a noncoding small RNA, SdhX, is produced by RNase E-dependent processing from the 3′UTR of thesdhCDAB-sucABCDoperon, encoding enzymes of the tricarboxylic acid (TCA) cycle. InEscherichia coli, SdhX negatively regulatesackA, which encodes an enzyme critical for degradation of the signaling molecule acetyl phosphate, while the downstreamptagene, encoding the enzyme critical for acetyl phosphate synthesis, is not significantly affected. This discoordinate regulation ofptaandackAincreases the accumulation of acetyl phosphate when SdhX is expressed. Mutations insdhXthat abolish regulation ofackAlead to more acetate in the medium (more overflow metabolism), as well as a strong growth defect in the presence of acetate as sole carbon source, when the AckA-Pta pathway runs in reverse. SdhX overproduction confers resistance to hydroxyurea, via regulation ofackA. SdhX abundance is tightly coupled to the transcription signals of TCA cycle genes but escapes all known posttranscriptional regulation. Therefore, SdhX expression directly correlates with transcriptional input to the TCA cycle, providing an effective mechanism for the cell to link the TCA cycle with acetate metabolism pathways.

scholarly journals Neuronal glucose metabolism is impaired while astrocytic TCA cycling is unaffected at symptomatic stages in the hSOD1G93A mouse model of amyotrophic lateral sclerosis

2018 ◽  
Vol 39 (9) ◽  
pp. 1710-1724 ◽  
Author(s):  
Tesfaye W Tefera ◽  
Karin Borges
Keyword(s):  
Spinal Cord ◽  
Glucose Metabolism ◽  
Mouse Model ◽  
Tca Cycle ◽  
Energy Deficit ◽  
Acetate Metabolism ◽  
Resonance Spectroscopy ◽  
Symptomatic Disease ◽  
The Tca Cycle ◽  
Disease Stages

Although alterations in energy metabolism are known in ALS, the specific mechanisms leading to energy deficit are not understood. We measured metabolite levels derived from injected [1-13C]glucose and [1,2-13C]acetate (i.p.) in cerebral cortex and spinal cord extracts of wild type and hSOD1G93A mice at onset and mid disease stages using high-pressure liquid chromatography, 1H and 13C nuclear magnetic resonance spectroscopy. Levels of spinal and cortical CNS total lactate, [3-13C]lactate, total alanine and [3-13C]alanine, but not cortical glucose and [1-13C]glucose, were reduced mostly at mid stage indicating impaired glycolysis. The [1-13C]glucose-derived [4-13C]glutamate, [4-13C]glutamine and [2-13C]GABA amounts were diminished at mid stage in cortex and both time points in spinal cord, suggesting decreased [3-13C]pyruvate entry into the TCA cycle. Lack of changes in [1,2-13C]acetate-derived [4,5-13C]glutamate, [4,5-13C]glutamine and [1,2-13C]GABA levels indicate unchanged astrocytic 13C-acetate metabolism. Reduced levels of leucine, isoleucine and valine in CNS suggest compensatory breakdown to refill TCA cycle intermediate levels. Unlabelled, [2-13C] and [4-13C]GABA concentrations were decreased in spinal cord indicating that impaired glucose metabolism contributes to hyperexcitability and supporting the use of treatments which increase GABA amounts. In conclusion, CNS glucose metabolism is compromised, while astrocytic TCA cycling appears to be normal in the hSOD1G93A mouse model at symptomatic disease stages.

scholarly journals Complete Remission with Devimistat (CPI-613) in Refractory Burkitt Lymphoma

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4555-4555
Author(s):  
Liana Nikolaenko ◽  
Timothy Pardee ◽  
Raphel Steiner ◽  
Jeremy S. Abramson ◽  
Steven M. Horwitz ◽  
...  
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Research Funding ◽  
Study Drug ◽  
Tca Cycle ◽  
Mitochondrial Enzymes ◽  
Advisory Committees ◽  
Cancer Cell Death ◽  
Redox Active ◽  
The Tca Cycle ◽  
Alpha Ketoglutarate Dehydrogenase

Abstract Introduction: Patients (pts) with primary refractory or relapsed high-grade lymphoma (HGL) including Burkitt lymphoma (BL) and high-grade B-cell lymphoma with rearrangements of MYC and BCL2 and/or BCL6 (double-hit lymphoma, DHL) have a dismal prognosis with patients almost never achieving a meaningful remission to second line therapy. No standard second line therapeutic approach exists, particularly for BL. The characteristic hallmark of these diseases is a dysregulated MYC oncogene with both downstream effects on proliferation and a high metabolic fluxes which use tricarboxylic acid (TCA) cycle intermediates as biosynthetic precursors. CPI-613 (devimistat) is a non-redox active analogue of lipoic acid, a required cofactor for two key mitochondrial enzymes of the TCA cycle, pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase. Disruption of mitochondrial function by CPI-613 results in a shutdown of ATP and biosynthetic-intermediate production, leading to cancer cell death by apoptosis or necrosis. In the initial phase I trial (n=26) one patient with multiply refractory BL had a partial remission sustained for over one year and then consolidated by surgical resection. She remains alive 7 years later. As of July 2021, 20 clinical studies for various cancers have been conducted (ongoing/completed) with devimistat with over 700 patients having received study drug. We initiated a phase II trial to further explore efficacy in HGL. Devimistat has FDA orphan status for BL and 4 other cancers. Methods: NCT03793140 is a multicenter study aiming to enroll 17 patients on each of two cohorts, BL and DHL, with a Simon's 2-stage design for each cohort, requiring one response among the first 9 treated patients to expand to 17. Patients must have had at least one prior line of therapy or are refusing standard of care and must be more than 3 months after a prior stem cell transplant. Active central nervous system (CNS) parenchymal disease is excluded, but prior leptomeningeal disease is allowed if the CSF is negative for more than 4 weeks at enrollment and maintenance intrathecal therapy is ongoing. Devimistat is given by central line over 2 hours daily x 5 days for two 14-day cycles and then as maintenance x5 days every 21 days. Pts were evaluable for response if they received at least 4 infusions over 5 days of the first cycle. Results: 9 pts were enrolled in the DHL/THL arm. Mediannumber of prior therapies were 3 (range, 1-6). No responses were seen, with only 1 patient achieving stable disease as best response, resulting in cohort closure. Thus far, 8 BL pts were enrolled. Median number of prior therapies was 3 (range, 2-4). Two patients were inevaluable for response. 1/6 patients had stable disease through cycle 7 and one had a complete response (CR). This CR patient (HIV+) with 4 prior therapies entered the study with only a biopsy proven thigh mass. He was not a transplant candidate for social reasons. He had a near complete metabolic remission after 4 cycles of devimistat and a CR after cycle 7. (Table and Figure) As of July 2021, he is in cycle 11, having had a 4-week treatment delay of cycle 5 due to CoVID 19 infection. ECOG improved from 3 to 0. Adverse events (AE): As of July30, 2021, no patient experienced a serious adverse event related to study drug. Four patients had grade 3 events at least possibly related: 2 neutropenia, 1 thrombocytopenia and 1 elevated bilirubin. 1 patient had a dose reduction for grade 2 alanine aminotransferase increase. Conclusions: Although our results are preliminary, the complete remission in this patient is promising in a disease where no viable treatment options exist in the relapsed, refractory BL. Enrollment to the BL cohort is ongoing. Figure 1 Figure 1. Disclosures Nikolaenko: Pfizer: Research Funding; Rafael Pharmaceuticals: Research Funding. Pardee: Celgene/BMS: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees; CBM Biopharma: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Research Funding; Rafael Pharmaceuticals: Research Funding. Abramson: Genentech: Consultancy; Kymera: Consultancy; Karyopharm: Consultancy; AbbVie: Consultancy; Seagen Inc.: Research Funding; Allogene Therapeutics: Consultancy; Astra-Zeneca: Consultancy; Incyte Corporation: Consultancy; BeiGene: Consultancy; Bluebird Bio: Consultancy; Genmab: Consultancy; EMD Serono: Consultancy; Bristol-Myers Squibb Company: Consultancy, Research Funding; C4 Therapeutics: Consultancy; Morphosys: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy. Horwitz: Vividion Therapeutics: Consultancy; Shoreline Biosciences, Inc.: Consultancy; Tubulis: Consultancy; Verastem: Research Funding; ONO Pharmaceuticals: Consultancy; Myeloid Therapeutics: Consultancy; SecuraBio: Consultancy, Research Funding; Trillium Therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Millennium /Takeda: Consultancy, Research Funding; Kura Oncology: Consultancy; Janssen: Consultancy; Kyowa Hakko Kirin: Consultancy, Research Funding; Forty Seven, Inc.: Research Funding; Daiichi Sankyo: Research Funding; C4 Therapeutics: Consultancy; Celgene: Research Funding; Aileron: Research Funding; Affimed: Research Funding; Acrotech Biopharma: Consultancy; ADC Therapeutics: Consultancy, Research Funding. Matasar: GlaxoSmithKline: Honoraria, Research Funding; Teva: Consultancy; Janssen: Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Genentech, Inc.: Consultancy, Honoraria, Research Funding; Merck Sharp & Dohme: Current holder of individual stocks in a privately-held company; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; IGM Biosciences: Research Funding; Merck: Consultancy; Juno Therapeutics: Consultancy; TG Therapeutics: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Research Funding; Memorial Sloan Kettering Cancer Center: Current Employment; Pharmacyclics: Honoraria, Research Funding; Daiichi Sankyo: Consultancy; ImmunoVaccine Technologies: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Rocket Medical: Consultancy, Research Funding. Noy: Rafael Parhma: Research Funding; Morphosys: Consultancy; Targeted Oncology: Consultancy; Medscape: Consultancy; Pharmacyclics: Consultancy, Research Funding; Janssen: Consultancy, Honoraria; Epizyme: Consultancy. OffLabel Disclosure: CPI-613 (devimistat) is a non-redox active analogue of lipoic acid, a required cofactor for two key mitochondrial enzymes of the TCA cycle, pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase. Disruption of mitochondrial function by CPI-613 results in a shutdown of ATP and biosynthetic-intermediate production, leading to cancer cell death by apoptosis or necrosis

scholarly journals Mll-Partial Tandem Duplication (Mll-PTD) Causes Pseudohypoxia and Hypermethylation of the Epigenome through Suppression of Mitochondrial Complex II

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1311-1311
Author(s):  
Asumi Yokota ◽  
Lulu Zhang ◽  
Xiaomei Yan ◽  
Xiaomin Feng ◽  
Lijun Wen ◽  
...  
Keyword(s):  
Protein Level ◽  
Tandem Duplication ◽  
Tca Cycle ◽  
Mitochondrial Activity ◽  
Mitochondrial Complex ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Tca Cycle Enzymes ◽  
The Tca Cycle ◽  
Partial Tandem Duplication

Abstract The MLL-partial tandem duplication (MLL-PTD),characterized by the internal duplication of exons 3-9 or 3-11 in the MLL gene, produces an elongated protein, and is considered as a gain-of-function mutation. The MLL-PTD is primarily found in elderly patients with myelodysplastic syndromes and acute myeloid leukemiaas well as healthy individuals.Previously we showed that Mll-PTD knock-in (MllPTD/WT) mice presented enhanced self-renewal of hematopoietic stem cells (HSCs) and partially blocked differentiation of hematopoietic stem/progenitor cells (HSPCs). Interestingly, Mll-PTD increased the protein level of HIF1A in HSPCs, which is critical for enhanced self-renewal of HSCs. In the current study, we investigated the mechanisms for HIF1A activation by Mll-PTD. In normoxia, HIF1A is hydroxylated by prolyl hydroxylases (PHD), resulting in rapid protein degradation via ubiquitination. PHD is one of the well-known enzymes whose activity is dependent on the cellular level of α-ketoglutarate (α-KG), one of the metabolites in the tricarboxylic acid (TCA) cycle. Accumulation of subsequent metabolites of α-KG, such as succinate, fumarate, and malate, inhibits activity of α-KG-dependent enzymes. Indeed, mitochondrial dysfunction is known to result in accumulation of TCA cycle intermediates, leading to activation of HIF signaling. Thus, we first examined if Mll-PTD induces the alteration of mitochondrial functions. Interestingly, cellular respiration and activity of mitochondrial complexes (I, II, and III) were significantly decreased in HSPCs of MllPTD/WT mice, while the copy number of mitochondrial DNA was not altered. These results indicate that suppression of mitochondrial activity is not due to the decrease of the total mitochondria. We also examined mRNA expression levels of several major TCA cycle enzymes, and found that succinate dehydrogenase (Sdh) complex (Sdha, Sdhb, and Sdhd) was significantly downregulated in MllPTD/WT HSPCs. SDH is a critical TCA cycle enzyme which converts succinate to fumarate. Inactivation of SDH is known to result in impairment of mitochondrial biogenesis, a blockade of the TCA cycle, and accumulation of TCA cycle metabolites. We next quantified metabolites in glycolysis and TCA cycle in the plasma from WT control and MllPTD/WT mice. NMR analysis revealed that succinate, fumarate, and malate were increased in the plasma of MllPTD/WT mice. Especially, the ratios of fumarate and malate to α-KG were both significantly increased in MllPTD/WT compared to WT control. Indeed, post-α-KG metabolites increased HIF1A protein in human cord blood CD34+cells in vitro, indicating that higher levels of succinate, fumarate, and malate to α-KG levels stabilize HIF1A. We also confirmed that knockdown of Sdh increased the HIF1A protein level in murine cell line in normoxia. These results indicate that downregulation of Sdh in MllPTD/WT is one of the mechanisms for suppression of mitochondrial activity, leading to pseudohypoxia and HIF1A activation. Besides PHD, TET and histone lysine demethylases are also α-KG-dependent enzymes. We found that in MllPTD/WT HSPCs, the 5-methylcitosine (5-mC) level was increased in genomic DNA, and trimethylation levels at H3K4, H3K9, H3K36 and H3K79 were also increased. Collectively, these results suggest that metabolic pseudohypoxia due to lower mitochondrial activity not only activates HIF1A signaling but also induces hypermethylation in DNA and histones, through suppression of α-KG-dependent PHD and demethylases. In summary, we demonstrate that through suppression of mitochondrial complex II, Mll-PTD causes pseudohypoxia and hypermethylation of the epigenome, which may contribute to expansion of premalignant clones and accumulation of additional mutations in those cells. Interestingly, it has been proposed that IDH mutations are involved in tumorigenesis in leukemias and brain tumors through a similar mechanism. Moreover, loss-of-function mutations of the TCA cycle enzymes, SDH complex, and fumarate hydratase, are frequently found in various solid tumors associated with pseudohypoxia and hypermethylation phenotypes. Further investigations of the impact of metabolic-rewiring-mediated pseudohypoxia/hypermethylation on tumorigenesis may lead to the development of novel therapeutic strategies to prevent the onset and/or the progression of various types of malignant diseases. Disclosures No relevant conflicts of interest to declare.

scholarly journals Molecular interaction studies on ellagic acid for its anticancer potential targeting pyruvate dehydrogenase kinase 3

RSC Advances ◽  
2019 ◽  
Vol 9 (40) ◽  
pp. 23302-23315 ◽  
Author(s):  
Rashmi Dahiya ◽  
Taj Mohammad ◽  
Preeti Gupta ◽  
Anzarul Haque ◽  
Mohamed F. Alajmi ◽  
...  
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Ellagic Acid ◽  
Molecular Interaction ◽  
Tca Cycle ◽  
Pyruvate Dehydrogenase Kinase ◽  
Reversible Phosphorylation ◽  
Interaction Studies ◽  
Metabolic Switching ◽  
The Tca Cycle

PDK3 plays a central role in cancer through the reversible phosphorylation of PDC thereby blocking the entry of pyruvate into the TCA cycle. PDK3 mediated metabolic switching can be therapeutically targeted for glycolysis addicted cancers.

scholarly journals BCKDK regulates the TCA cycle through PDC to ensure embryonic development in the absence of PDK family

2020 ◽  
Author(s):  
Lia Heinemann-Yerushalmi ◽  
Lital Bentovim ◽  
Neta Felsenthal ◽  
Ron Carmel Vinestock ◽  
Nofar Michaeli ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Tca Cycle ◽  
Bioinformatic Analysis ◽  
Compensatory Mechanism ◽  
The Tca Cycle ◽  
Early Embryonic Lethality ◽  
Branched Chain ◽  
Ketoacid Dehydrogenase

AbstractPyruvate dehydrogenase kinases (PDK1-4) inhibit the TCA cycle by phosphorylating pyruvate dehydrogenase complex (PDC). Here, we show that the PDK family is dispensable for the survival of murine embryonic development and that BCKDK serves as a compensatory mechanism by inactivating PDC.First, we knocked out all fourPdkgenes one by one. Surprisingly,Pdktotal KO embryos developed and were born in expected ratios, but died by postnatal day 4 due to hypoglycemia or ketoacidosis.Finding that PDC was phosphorylated in these embryos suggested that another kinase compensates for the PDK family. Bioinformatic analysis implicated brunch chain ketoacid dehydrogenase kinase (Bckdk), a key regulator of branched chain amino acids (BCAA) catabolism. Indeed, knockout ofBckdkand thePdkfamily led to loss of PDC phosphorylation, increment in PDC activity, elevation of Pyruvate flux into the TCA and early embryonic lethality. These findings reveal a new regulatory crosstalk hardwiring BCAA and glucose catabolic pathways, which feed the TCA cycle.

scholarly journals Triheptanoin alters [U-13C6]-glucose incorporation into glycolytic intermediates and increases TCA cycling by normalizing the activities of pyruvate dehydrogenase and oxoglutarate dehydrogenase in a chronic epilepsy mouse model

2019 ◽  
Vol 40 (3) ◽  
pp. 678-691 ◽  
Author(s):  
Tanya McDonald ◽  
Mark P Hodson ◽  
Ilya Bederman ◽  
Michelle Puchowicz ◽  
Karin Borges
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Glucose Utilization ◽  
Tca Cycle ◽  
The Tca Cycle ◽  
Seizure Models ◽  
Glycolytic Intermediates ◽  
Oxoglutarate Dehydrogenase ◽  
Tca Cycle Intermediates ◽  
Interictal State ◽  
Glycogen Breakdown

Triheptanoin is anticonvulsant in several seizure models. Here, we investigated changes in glucose metabolism by triheptanoin interictally in the chronic stage of the pilocarpine mouse epilepsy model. After injection of [U-13C6]-glucose (i.p.), enrichments of 13C in intermediates of glycolysis and the tricarboxylic acid (TCA) cycle were quantified in hippocampal extracts and maximal activities of enzymes in each pathway were measured. The enrichment of 13C glucose in plasma was similar across all groups. Despite this, we observed reductions in incorporation of 13C in several glycolytic intermediates compared to control mice suggesting glucose utilization may be impaired and/or glycogenolysis increased in the untreated interictal hippocampus. Triheptanoin prevented the interictal reductions of 13C incorporation in most glycolytic intermediates, suggesting it increased glucose utilization or – as an additional astrocytic fuel – it decreased glycogen breakdown. In the TCA cycle metabolites, the incorporation of 13C was reduced in the interictal state. Triheptanoin restored the correlation between 13C enrichments of pyruvate relative to most of the TCA cycle intermediates in “epileptic” mice. Triheptanoin also prevented the reductions of hippocampal pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase activities. Decreased glycogen breakdown and increased glucose utilization and metabolism via the TCA cycle in epileptogenic brain areas may contribute to triheptanoin's anticonvulsant effects.

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