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Broxton CN, Kaur P, Lavorato M, Ganesh S, Xiao R, Mathew ND, Nakamaru-Ogiso E, Anderson VE, Falk MJ. Dichloroacetate and thiamine improve survival and mitochondrial stress in a C. elegans model of dihydrolipoamide dehydrogenase deficiency. JCI Insight 2022; 7:e156222. [PMID: 36278487 PMCID: PMC9714793 DOI: 10.1172/jci.insight.156222] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 09/12/2022] [Indexed: 01/16/2023] Open
Abstract
Dihydrolipoamide dehydrogenase (DLD) deficiency is a recessive mitochondrial disorder caused by depletion of DLD from α-ketoacid dehydrogenase complexes. Caenorhabditis elegans animal models of DLD deficiency generated by graded feeding of dld-1(RNAi) revealed that full or partial reduction of DLD-1 expression recapitulated increased pyruvate levels typical of pyruvate dehydrogenase complex deficiency and significantly altered animal survival and health, with reductions in brood size, adult length, and neuromuscular function. DLD-1 deficiency dramatically increased mitochondrial unfolded protein stress response induction and adaptive mitochondrial proliferation. While ATP levels were reduced, respiratory chain enzyme activities and in vivo mitochondrial membrane potential were not significantly altered. DLD-1 depletion directly correlated with the induction of mitochondrial stress and impairment of worm growth and neuromuscular function. The safety and efficacy of dichloroacetate, thiamine, riboflavin, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), l-carnitine, and lipoic acid supplemental therapies empirically used for human DLD disease were objectively evaluated by life span and mitochondrial stress response studies. Only dichloroacetate and thiamine showed individual and synergistic therapeutic benefits. Collectively, these C. elegans dld-1(RNAi) animal model studies demonstrate the translational relevance of preclinical modeling of disease mechanisms and therapeutic candidates. Results suggest that clinical trials are warranted to evaluate the safety and efficacy of dichloroacetate and thiamine in human DLD disease.
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Affiliation(s)
- Chynna N. Broxton
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Prabhjot Kaur
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Manuela Lavorato
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Smruthi Ganesh
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | - Neal D. Mathew
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Eiko Nakamaru-Ogiso
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Vernon E. Anderson
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Marni J. Falk
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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Ahmad W, Ebert PR. Suppression of a core metabolic enzyme dihydrolipoamide dehydrogenase ( dld) protects against amyloid beta toxicity in C. elegans model of Alzheimer's disease. Genes Dis 2021; 8:849-866. [PMID: 34522713 PMCID: PMC8427249 DOI: 10.1016/j.gendis.2020.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/24/2020] [Accepted: 08/14/2020] [Indexed: 01/24/2023] Open
Abstract
A decrease in energy metabolism is associated with Alzheimer's disease (AD), but it is not known whether the observed decrease exacerbates or protects against the disease. The importance of energy metabolism in AD is reinforced by the observation that variants of dihydrolipoamide dehydrogenase (DLD), is genetically linked to late-onset AD. To determine whether DLD is a suitable therapeutic target, we suppressed the dld-1 gene in Caenorhabditis elegans that express human Aβ peptide in either muscles or neurons. Suppression of the dld-1 gene resulted in significant restoration of vitality and function that had been degraded by Aβ pathology. This included protection of neurons and muscles cells. The observed decrease in proteotoxicity was associated with a decrease in the formation of toxic oligomers rather than a decrease in the abundance of the Aβ peptide. The mitochondrial uncoupler, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), which like dld-1 gene expression inhibits ATP synthesis, had no significant effect on Aβ toxicity. Proteomics data analysis revealed that beneficial effects after dld-1 suppression could be due to change in energy metabolism and activation of the pathways associated with proteasomal degradation, improved cell signaling and longevity. Thus, some features unique to dld-1 gene suppression are responsible for the therapeutic benefit. By direct genetic intervention, we have shown that acute inhibition of dld-1 gene function may be therapeutically beneficial. This result supports the hypothesis that lowering energy metabolism protects against Aβ pathogenicity and that DLD warrants further investigation as a therapeutic target.
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Affiliation(s)
- Waqar Ahmad
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Paul R. Ebert
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
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Jaiswal M, Haelterman NA, Sandoval H, Xiong B, Donti T, Kalsotra A, Yamamoto S, Cooper TA, Graham BH, Bellen HJ. Impaired Mitochondrial Energy Production Causes Light-Induced Photoreceptor Degeneration Independent of Oxidative Stress. PLoS Biol 2015; 13:e1002197. [PMID: 26176594 PMCID: PMC4503542 DOI: 10.1371/journal.pbio.1002197] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 06/10/2015] [Indexed: 11/19/2022] Open
Abstract
Two insults often underlie a variety of eye diseases including glaucoma, optic atrophy, and retinal degeneration—defects in mitochondrial function and aberrant Rhodopsin trafficking. Although mitochondrial defects are often associated with oxidative stress, they have not been linked to Rhodopsin trafficking. In an unbiased forward genetic screen designed to isolate mutations that cause photoreceptor degeneration, we identified mutations in a nuclear-encoded mitochondrial gene, ppr, a homolog of human LRPPRC. We found that ppr is required for protection against light-induced degeneration. Its function is essential to maintain membrane depolarization of the photoreceptors upon repetitive light exposure, and an impaired phototransduction cascade in ppr mutants results in excessive Rhodopsin1 endocytosis. Moreover, loss of ppr results in a reduction in mitochondrial RNAs, reduced electron transport chain activity, and reduced ATP levels. Oxidative stress, however, is not induced. We propose that the reduced ATP level in ppr mutants underlies the phototransduction defect, leading to increased Rhodopsin1 endocytosis during light exposure, causing photoreceptor degeneration independent of oxidative stress. This hypothesis is bolstered by characterization of two other genes isolated in the screen, pyruvate dehydrogenase and citrate synthase. Their loss also causes a light-induced degeneration, excessive Rhodopsin1 endocytosis and reduced ATP without concurrent oxidative stress, unlike many other mutations in mitochondrial genes that are associated with elevated oxidative stress and light-independent photoreceptor demise. Some mitochondrial disorders cause blindness through increased oxidative stress. This study shows that in other such disorders, light-activated photoreceptors degenerate because the shortfall in mitochondrial energy production impairs rhodopsin trafficking and induces toxicity. Mitochondrial dysfunction is associated with a number of metabolic and neurological diseases such as Leigh syndrome and progressive blindness. Increased oxidative stress, which is often associated with mitochondrial dysfunction, is thought to be a common cause of disease progression. Here, we identified nuclear genes that encode mitochondrial proteins, whose loss causes the demise of photoreceptor neurons. Contrary to the common idea that this degeneration is triggered by elevated levels of oxidative stress, we find no change in the levels of oxidative stress. We show that activating photoreceptor neurons with light significantly increases energy production, and that this process is required to sustain their activity. Mitochondrial dysfunction impairs this capacity and leads to a premature termination of the light response. This in turn impairs the cycling of the light-sensitive receptor Rhodopsin in photoreceptors, and Rhodopsin accumulates in the cell inducing toxicity. This distinct mechanism of degeneration suggests that different mitochondrial diseases may follow different paths of disease progression and would hence respond differently to treatments.
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Affiliation(s)
- Manish Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, Texas, United States of America
- Howard Hughes Medical Institute, BCM, Houston, Texas, United States of America
| | - Nele A. Haelterman
- Program in Developmental Biology, BCM, Houston, Texas, United States of America
| | - Hector Sandoval
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, Texas, United States of America
| | - Bo Xiong
- Program in Developmental Biology, BCM, Houston, Texas, United States of America
| | - Taraka Donti
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, Texas, United States of America
| | - Auinash Kalsotra
- Department of Pathology and Immunology, BCM, Houston, Texas, United States of America
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, Texas, United States of America
- Program in Developmental Biology, BCM, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital (TCH), Houston, Texas, United States of America
| | - Thomas A. Cooper
- Program in Developmental Biology, BCM, Houston, Texas, United States of America
- Department of Pathology and Immunology, BCM, Houston, Texas, United States of America
| | - Brett H. Graham
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, Texas, United States of America
| | - Hugo J. Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, Texas, United States of America
- Howard Hughes Medical Institute, BCM, Houston, Texas, United States of America
- Program in Developmental Biology, BCM, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital (TCH), Houston, Texas, United States of America
- Department of Neuroscience, BCM, Houston, Texas, United States of America
- * E-mail:
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Molecular dynamics study of the structural basis of dysfunction and the modulation of reactive oxygen species generation by pathogenic mutants of human dihydrolipoamide dehydrogenase. Arch Biochem Biophys 2013; 538:145-55. [PMID: 24012808 DOI: 10.1016/j.abb.2013.08.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 08/09/2013] [Accepted: 08/26/2013] [Indexed: 12/15/2022]
Abstract
Human dihydrolipoamide dehydrogenase (LADH, E3) is a component in the pyruvate-, alpha-ketoglutarate- and branched-chain ketoacid dehydrogenase complexes and in the glycine cleavage system. The pathogenic mutations of LADH cause severe metabolic disturbances, called E3 deficiency that often involve cardiological and neurological symptoms and premature death. Our laboratory has recently shown that some of the known pathogenic mutations augment the reactive oxygen species (ROS) generation capacity of LADH, which may contribute to the clinical presentations. A recent report concluded that elevated oxidative stress generated by the above mutants turns the lipoic acid cofactor on the E2 subunits dysfunctional. In the present contribution we generated by molecular dynamics (MD) simulation the conformation of LADH that is proposed to be compatible with ROS generation. We propose here for the first time the structural changes, which are likely to turn the physiological LADH conformation to its ROS-generating conformation. We also created nine of the pathogenic mutants of the ROS-generating conformation and again used MD simulation to detect structural changes that the mutations induced in this LADH conformation. We propose the structural changes that may lead to the modulation in ROS generation of LADH by the pathogenic mutations.
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Negari SBH, Aouizerat T, Tenenbaum A, Cohen-Cymberknoh M, Shoseyov D, Kerem E, Saada A. Mitochondrial OXPHOS function is unaffected by chronic azithromycin treatment. J Cyst Fibros 2013; 12:682-7. [PMID: 23680642 DOI: 10.1016/j.jcf.2013.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 03/11/2013] [Accepted: 04/17/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Certain antibiotics may cause unwanted side effects due to the similarity of the mitochondrial translation system to the prokaryotic one. Children with cystic fibrosis (CF) are vulnerable to recurrent respiratory tract infections and azithromycin, a translation targeted antibiotic, is often used chronically to treat CF patients. No major clinical side effects were found with chronic treatment. However, mitochondrial function was not previously assessed. We evaluated oxidative phosphorylation (OXPHOS) in lymphocytes from children with CF receiving chronic azithromycin treatment using an improved ATP production assay. METHOD Enzymatic activities of respiratory chain complexes II-IV and ATP production were measured in lymphocytes. RESULTS Relative to controls and to CF patients without azithromycin treatment, no significant difference in mitochondrial respiratory chain complexes II-IV was detected, and ATP production with pyruvate, glutamate and succinate, did not disclose any differences between the groups. CONCLUSION We suggest that chronic treatment with azithromycin does not significantly affect OXPHOS function.
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Affiliation(s)
- Shelly Ben-Harush Negari
- Monique and Jacques Roboh Department of Genetic Research Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem 91120, Israel; Department of Pediatrics Hadassah-Hebrew University Medical Center, Jerusalem Israel; Division of Adolescent Medicine Cincinnati Children's Hospital Medical Center, OH, USA
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Rapoport M, Salman L, Sabag O, Patel MS, Lorberboum-Galski H. Successful TAT-mediated enzyme replacement therapy in a mouse model of mitochondrial E3 deficiency. J Mol Med (Berl) 2010; 89:161-70. [PMID: 21079907 DOI: 10.1007/s00109-010-0693-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 10/21/2010] [Accepted: 10/26/2010] [Indexed: 11/25/2022]
Abstract
Medicine today offers no cure for patients suffering from mitochondrial disorders, such as lipoamide dehydrogenase (LAD; also known as E3) deficiency, and treatment is limited to symptomatic care. LAD is one of the components of the α-ketoacid dehydrogenase complexes, which are mitochondrial multienzyme complexes crucial for the metabolism of carbohydrates and amino acids. Recently, we tested the therapeutic approach for treating mitochondrial disorders whereby the activity of multicomponent complexes in the mitochondria is restored by TAT-mediated enzyme replacement therapy (ERT). The LAD deficiency disease was used before as a proof-of-principle in vitro, in patients' cells, utilizing the TAT-LAD fusion protein. In this report, we present successful TAT-mediated ERT in an in vivo mouse model using E3-deficient mice. We demonstrate the delivery of TAT-LAD into E3-deficient mice tissues and that a single administration of TAT-LAD results in a significant increase in the enzymatic activity of the mitochondrial multienzyme complex pyruvate dehydrogenase complex within the liver, heart and, most importantly, the brain of TAT-LAD-treated E3-deficient mice. We believe that this TAT-mediated ERT approach could change the management of mitochondrial disorders and of other metabolic diseases in modern medicine.
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Affiliation(s)
- Matan Rapoport
- Department of Biochemistry and Molecular Biology, Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel
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Berger I, Segal I, Shmueli D, Saada A. The effect of antiepileptic drugs on mitochondrial activity: a pilot study. J Child Neurol 2010; 25:541-5. [PMID: 20413803 DOI: 10.1177/0883073809352888] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mitochondria are probably a target in antiepileptic drug-induced hepatotoxicity accompanied by oxidative stress. Most studies discuss valproic acid. The information regarding other antiepileptic drugs is scarce. Most studies used in vitro methods and animal models. In this study, the authors have investigated the effect of antiepileptic drugs, other than valproic acid, on the oxidative phosphorylation process in children, by measuring mitochondrial adenosine triphosphate (ATP) production and the enzymatic activities of respiratory chain complexes II-IV in peripheral white blood cells. The results demonstrate that several antiepileptic drugs can affect the mitochondrial oxidative phosphorylation. The authors have concluded that the effect of antiepileptic drugs on the mitochondria is not limited only to valproic acid, but can affect different mitochondrial pathways and can be performed in humans by relatively simple methods, using small samples of peripheral white blood cells.
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Affiliation(s)
- Itai Berger
- The Neuro-Pediatric Unit, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
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8
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Johnson M, Vang P, Filipovits J, Gardner D. Maternal enzyme masks the phenotype of mouse embryos lacking dihydrolipoamide dehydrogenase. Reprod Biomed Online 2009; 19:79-88. [PMID: 19573295 DOI: 10.1016/s1472-6483(10)60050-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
During early embryogenesis, the phenotype reflecting the embryonic genotype emerges only as maternal proteins are replaced by embryonically encoded forms, a process known as the maternal-to-embryonic transition (MET). Little is understood about MET for most proteins. This study investigates how complete deficiency of the murine dihydrolipoamide dehydrogenase gene (Dld), a gene that encodes an enzyme of mitochondrial energy metabolism, affects the phenotype of the early embryo and how the MET of the DLD protein affects the phenotype. Dld-deficient (-/-) embryos were found to develop similarly to wild-type (+/+) or heterozygous (+/-) embryos throughout the preimplantation period. These three genotypic classes also have comparable rates of glucose uptake (4.9-5.0 pmoles/embryo/h) and lactate production (0.97-1.0 pmoles/embryo/h). Dld-deficient embryos at the end of the preimplantation stage have 44% of DLD enzyme present in oocytes, a proportion similar to that found in +/+ or +/- embryos. This study demonstrates that Dld-deficient preimplantation embryos are phenotypically normal, as the MET for the DLD enzyme is only partially complete by the end of the preimplantation period. These findings have implications for phenotype- or enzyme-based approaches to identify mutations in Dld and other genes that encode proteins with similar MET kinetic profiles.
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Affiliation(s)
- Mark Johnson
- Department of Obstetrics and Gynecology, University of Michigan School of Medicine, 1150 W. Medical Center Dr., 6422 Med Sci I, Ann Arbor, MI 48109-0617, USA.
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TAT-mediated Delivery of LAD Restores Pyruvate Dehydrogenase Complex Activity in the Mitochondria of Patients with LAD Deficiency. Mol Ther 2008; 16:691-7. [DOI: 10.1038/mt.2008.4] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Rapoport M, Saada A, Elpeleg O, Lorberboum-Galski H. TAT-mediated Delivery of LAD Restores Pyruvate Dehydrogenase Complex Activity in the Mitochondria of Patients with LAD Deficiency. Mol Ther 2008. [DOI: 10.1038/sj.mt.6300410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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12
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Luís PBM, Ruiter JPN, Aires CCP, Soveral G, de Almeida IT, Duran M, Wanders RJA, Silva MFB. Valproic acid metabolites inhibit dihydrolipoyl dehydrogenase activity leading to impaired 2-oxoglutarate-driven oxidative phosphorylation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1126-33. [PMID: 17706936 DOI: 10.1016/j.bbabio.2007.06.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 06/21/2007] [Accepted: 06/26/2007] [Indexed: 11/26/2022]
Abstract
The effect of the antiepileptic drug valproic acid (VPA) on mitochondrial oxidative phosphorylation (OXPHOS) was investigated in vitro. Two experimental approaches were used, in the presence of selected respiratory-chain substrates: (1) formation of ATP in digitonin permeabilized rat hepatocytes and (2) measurement of the rate of oxygen consumption by polarography in rat liver mitochondria. VPA (0.1-1.0 mM) was found to inhibit oxygen consumption and ATP synthesis under state 3 conditions with glutamate and 2-oxoglutarate as respiratory substrates. No inhibitory effect on OXPHOS was observed when succinate (plus rotenone) was used as substrate. We tested the hypothesis that dihydrolipoyl dehydrogenase (DLDH) might be a direct target of VPA, especially its acyl-CoA intermediates. Valproyl-CoA (0.5-1.0 mM) and valproyl-dephosphoCoA (0.5-1.0 mM) both inhibited the DLDH activity, acting apparently by different mechanisms. The decreased activity of DLDH induced by VPA metabolites may, at least in part, account for the impaired rate of oxygen consumption and ATP synthesis in mitochondria if 2-oxoglutarate or glutamate were used as respiratory substrates, thus limiting the flux of these substrates through the citric acid cycle.
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Affiliation(s)
- Paula B M Luís
- Centro de Patogénese Molecular, Unidade de Biologia Molecular e Biopatologia Experimental, (UBMBE) Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
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Reisch AS, Elpeleg O. Biochemical assays for mitochondrial activity: assays of TCA cycle enzymes and PDHc. Methods Cell Biol 2007; 80:199-222. [PMID: 17445696 DOI: 10.1016/s0091-679x(06)80010-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Ann Saada Reisch
- The Metabolic Disease Unit, Hadassah-Hebrew University Medical Centre, Jerusalem 91120, Israel
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14
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Fedotcheva NI, Sokolov AP, Kondrashova MN. Nonezymatic formation of succinate in mitochondria under oxidative stress. Free Radic Biol Med 2006; 41:56-64. [PMID: 16781453 DOI: 10.1016/j.freeradbiomed.2006.02.012] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 02/03/2006] [Accepted: 02/18/2006] [Indexed: 11/26/2022]
Abstract
The products of the reactions of mitochondrial 2-oxo acids with hydrogen peroxide and tert-butyl hydroperoxide (tert-BuOOH) were studied in a chemical system and in rat liver mitochondria. It was found by HPLC that the decarboxylation of alpha-ketoglutarate (KGL), pyruvate (PYR), and oxaloacetate (OA) by both oxidants results in the formation of succinate, acetate, and malonate, respectively. The two latter products do not metabolize in rat liver mitochondria, whereas succinate is actively oxidized, and its nonenzymatic formation from KGL may shunt the tricarboxylic acid (TCA) cycle upon inactivation of alpha-ketoglutarate dehydrogenase (KGDH) under oxidative stress, which is inherent in many diseases and aging. The occurrence of nonenzymatic oxidation of KGL in mitochondria was established by an increase in the CO(2) and succinate levels in the presence of the oxidants and inhibitors of enzymatic oxidation. H(2)O(2) and menadione as an inductor of reactive oxygen species (ROS) caused the formation of CO(2) in the presence of sodium azide and the production of succinate, fumarate, and malate in the presence of rotenone. These substrates were also formed from KGL when mitochondria were incubated with tert-BuOOH at concentrations that completely inhibit KGDH. The nonenzymatic oxidation of KGL can support the TCA cycle under oxidative stress, provided that KGL is supplied via transamination. This is supported by the finding that the strong oxidant such as tert-BuOOH did not impair respiration and its sensitivity to the transaminase inhibitor aminooxyacetate when glutamate and malate were used as substrates. The appearance of two products, KGL and fumarate, also favors the involvement of transamination. Thus, upon oxidative stress, nonenzymatic decarboxylation of KGL and transamination switch the TCA cycle to the formation and oxidation of succinate.
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Affiliation(s)
- Nadezhda I Fedotcheva
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia.
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Saada A, Bar-Meir M, Belaiche C, Miller C, Elpeleg O. Evaluation of enzymatic assays and compounds affecting ATP production in mitochondrial respiratory chain complex I deficiency. Anal Biochem 2005; 335:66-72. [PMID: 15519572 DOI: 10.1016/j.ab.2004.08.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Indexed: 11/29/2022]
Abstract
Isolated complex I deficiency is the most common oxidative phosphorylation defect and is associated with substantial morbidity and mortality. The diagnosis is made by enzymatic analysis and for most patients the molecular pathology remains undefined. Various cofactors and vitamins are frequently administered, but their efficacy have been difficult to assess. We employed determination of ATP production in fibroblast cell lines from patients with complex I deficiency to evaluate the usefulness of therapeutic agents. The effect of each additive varied among the different patients with certain agents favorably affecting ATP production rate in some of the patients and adversely affecting it in others. The reduced nicotinamide adenine dinucleotide (NADH)-ferricyanide reductase assay in muscle mitochondria correlated better than the NADH-coenzyme Q and NADH-cytochrome c assays with ATP production rate in fibroblasts. Our results underscore the necessity of evaluation of different agents for each patient separately. The NADH-ferricyanide reductase assay play a helpful role in directing mutation analysis and identifying patients which are more likely to have their cells amenable for ATP production assessment.
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Affiliation(s)
- Ann Saada
- Metabolic Disease Unit, Shaare-Zedek Medical Center, POB 3235, Jerusalem 91031, Israel.
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Taylor MR, Hurley JB, Van Epps HA, Brockerhoff SE. A zebrafish model for pyruvate dehydrogenase deficiency: rescue of neurological dysfunction and embryonic lethality using a ketogenic diet. Proc Natl Acad Sci U S A 2004; 101:4584-9. [PMID: 15070761 PMCID: PMC384790 DOI: 10.1073/pnas.0307074101] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Defects in the pyruvate dehydrogenase (PDH) complex result in severe neurological dysfunction, congenital lactic acidosis, growth retardation, and early death. Current treatments for PDH deficiency are administered postnatally and are generally unsuccessful. Because many patients with this disease are born with irreversible defects, a model system for the development of effective pre- and postnatal therapies would be of great value. In a behavioral genetic screen aimed to identify zebrafish with visual function defects, we previously isolated two alleles of the recessive lethal mutant no optokinetic response a (noa). Here we report that noa is deficient for dihydrolipoamide S-acetyltransferase (Dlat), the PDH E2 subunit, and exhibits phenotypes similar to human patients with PDH deficiency. To rescue the deficiency, we added ketogenic substrates to the water in which the embryos develop. This treatment successfully restored vision, promoted feeding behavior, reduced lactic acidosis, and increased survival. Our study demonstrates an approach for establishing effective therapies for PDH deficiency and other congenital diseases that affect early embryonic development.
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Affiliation(s)
- Michael R Taylor
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7350, USA.
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Arivazhagan P, Panneerselvam C. Effect of DL-α-Lipoic Acid on the Status of Lipids and Membrane-Bound ATPases in Various Brain Regions of Aged Rats. ACTA ACUST UNITED AC 2002. [DOI: 10.1089/109454502763485458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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