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Zaganas I, Vorgia P, Spilioti M, Mathioudakis L, Raissaki M, Ilia S, Giorgi M, Skoula I, Chinitrakis G, Michaelidou K, Paraskevoulakos E, Grafakou O, Kariniotaki C, Psyllou T, Zafeiris S, Tzardi M, Briassoulis G, Dinopoulos A, Mitsias P, Evangeliou A. Genetic cause of epilepsy in a Greek cohort of children and young adults with heterogeneous epilepsy syndromes. Epilepsy Behav Rep 2021; 16:100477. [PMID: 34568804 PMCID: PMC8449081 DOI: 10.1016/j.ebr.2021.100477] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 08/17/2021] [Accepted: 08/23/2021] [Indexed: 12/01/2022] Open
Abstract
We describe a cohort of 10 unrelated Greek patients (4 females, 6 males; median age 6.5 years, range 2-18 years) with heterogeneous epilepsy syndromes with a genetic basis. In these patients, causative genetic variants, including two novel ones, were identified in 9 known epilepsy-related genes through whole exome sequencing. A patient with glycine encephalopathy was a compound heterozygote for the p.Arg222Cys and the p.Ser77Leu AMT variant. A patient affected with Lafora disease carried the homozygous p.Arg171His EPM2A variant. A de novo heterozygous variant in the GABRG2 gene (p.Pro282Thr) was found in one patient and a pathogenic variant in the GRIN2B gene (p.Gly820Val) in another patient. Infantile-onset lactic acidosis with seizures was associated with the p.Arg446Ter PDHX gene variant in one patient. In two additional epilepsy patients, the p.Ala1662Val and the novel non-sense p.Phe1330Ter SCN1A gene variants were found. Finally, in 3 patients we observed a novel heterozygous missense variant in SCN2A (p.Ala1874Thr), a heterozygous splice site variant in SLC2A1 (c.517-2A>G), as a cause of Glut1 deficiency syndrome, and a pathogenic variant in STXBP1 (p.Arg292Leu), respectively. In half of our cases (patients with variants in the GRIN2B, SCN1A, SCN2A and SLC2A1 genes), a genetic cause with potential management implications was identified.
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Affiliation(s)
- Ioannis Zaganas
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
- Neurology Department, University Hospital of Heraklion, Crete, Greece
| | - Pelagia Vorgia
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Martha Spilioti
- AHEPA General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Lambros Mathioudakis
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Maria Raissaki
- Department of Radiology, University Hospital of Heraklion, Crete, Greece
| | - Stavroula Ilia
- Pediatric Intensive Care Unit, University Hospital of Heraklion, Crete, Greece
| | | | - Irene Skoula
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | | | - Kleita Michaelidou
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | | | - Olga Grafakou
- Pediatric Department, Venizelion General Hospital, Heraklio, Crete, Greece
| | - Chariklia Kariniotaki
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Thekla Psyllou
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Spiros Zafeiris
- Neurology Department, University Hospital of Heraklion, Crete, Greece
| | - Maria Tzardi
- Pathology Department, Medical School, University of Crete, Greece
| | - George Briassoulis
- Pediatric Intensive Care Unit, University Hospital of Heraklion, Crete, Greece
| | | | - Panayiotis Mitsias
- Neurology Department, University Hospital of Heraklion, Crete, Greece
- Department of Neurology, Henry Ford Hospital/Wayne State University, Detroit, MI, USA
| | - Athanasios Evangeliou
- Papageorgiou General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Pavlu-Pereira H, Silva MJ, Florindo C, Sequeira S, Ferreira AC, Duarte S, Rodrigues AL, Janeiro P, Oliveira A, Gomes D, Bandeira A, Martins E, Gomes R, Soares S, Tavares de Almeida I, Vicente JB, Rivera I. Pyruvate dehydrogenase complex deficiency: updating the clinical, metabolic and mutational landscapes in a cohort of Portuguese patients. Orphanet J Rare Dis 2020; 15:298. [PMID: 33092611 PMCID: PMC7579914 DOI: 10.1186/s13023-020-01586-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 10/13/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The pyruvate dehydrogenase complex (PDC) catalyzes the irreversible decarboxylation of pyruvate into acetyl-CoA. PDC deficiency can be caused by alterations in any of the genes encoding its several subunits. The resulting phenotype, though very heterogeneous, mainly affects the central nervous system. The aim of this study is to describe and discuss the clinical, biochemical and genotypic information from thirteen PDC deficient patients, thus seeking to establish possible genotype-phenotype correlations. RESULTS The mutational spectrum showed that seven patients carry mutations in the PDHA1 gene encoding the E1α subunit, five patients carry mutations in the PDHX gene encoding the E3 binding protein, and the remaining patient carries mutations in the DLD gene encoding the E3 subunit. These data corroborate earlier reports describing PDHA1 mutations as the predominant cause of PDC deficiency but also reveal a notable prevalence of PDHX mutations among Portuguese patients, most of them carrying what seems to be a private mutation (p.R284X). The biochemical analyses revealed high lactate and pyruvate plasma levels whereas the lactate/pyruvate ratio was below 16; enzymatic activities, when compared to control values, indicated to be independent from the genotype and ranged from 8.5% to 30%, the latter being considered a cut-off value for primary PDC deficiency. Concerning the clinical features, all patients displayed psychomotor retardation/developmental delay, the severity of which seems to correlate with the type and localization of the mutation carried by the patient. The therapeutic options essentially include the administration of a ketogenic diet and supplementation with thiamine, although arginine aspartate intake revealed to be beneficial in some patients. Moreover, in silico analysis of the missense mutations present in this PDC deficient population allowed to envisage the molecular mechanism underlying these pathogenic variants. CONCLUSION The identification of the disease-causing mutations, together with the functional and structural characterization of the mutant protein variants, allow to obtain an insight on the severity of the clinical phenotype and the selection of the most appropriate therapy.
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Affiliation(s)
- Hana Pavlu-Pereira
- Metabolism and Genetics Group, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
| | - Maria João Silva
- Metabolism and Genetics Group, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Cristina Florindo
- Metabolism and Genetics Group, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
| | - Sílvia Sequeira
- Department of Pediatrics, Hospital D. Estefânia, Lisbon, Portugal
| | | | - Sofia Duarte
- Department of Pediatrics, Hospital D. Estefânia, Lisbon, Portugal
| | | | - Patrícia Janeiro
- Department of Pediatrics, Hospital Santa Maria, Lisbon, Portugal
| | | | - Daniel Gomes
- Department of Medicine, Hospital Santa Maria, Lisbon, Portugal
| | - Anabela Bandeira
- Department of Pediatrics, Hospital Santo António, Porto, Portugal
| | | | - Roseli Gomes
- Department of Neuropediatrics, Hospital Pedro Hispano, Matosinhos, Portugal
| | - Sérgia Soares
- Department of Neuropediatrics, Hospital Pedro Hispano, Matosinhos, Portugal
| | - Isabel Tavares de Almeida
- Metabolism and Genetics Group, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - João B Vicente
- Instituto de Tecnologia Química e Biológica António Xavier, NOVA University of Lisbon, Av. da República (Estação Agronómica Nacional), 2780-157, Oeiras, Portugal.
| | - Isabel Rivera
- Metabolism and Genetics Group, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal.
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal.
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Wang W, Liang K, Chang Y, Ran M, Zhang Y, Ali MA, Dai D, Qazi IH, Zhang M, Zhou G, Yang J, Angel C, Zeng C. miR-26a is Involved in Glycometabolism and Affects Boar Sperm Viability by Targeting PDHX. Cells 2020; 9:E146. [PMID: 31936222 PMCID: PMC7016825 DOI: 10.3390/cells9010146] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/26/2019] [Accepted: 12/27/2019] [Indexed: 02/06/2023] Open
Abstract
miR-26a is associated with sperm metabolism and can affect sperm motility and apoptosis. However, how miR-26a affects sperm motility remains largely unknown. Our previous study indicated that the PDHX gene is predicted to be a potential target of miR-26a, which is responsible for pyruvate oxidative decarboxylation which is considered as a key step for connecting glycolysis with oxidative phosphorylation. In this study, we first reported a potential relationship between miR-26a and PDHX and their expressions in fresh, frozen-thawed, and epididymal boar sperm. Then, sperm viability and survival were determined after transfection of miR-26a. mRNA and protein expression level of PDHX in the liquid-preserved boar sperm after transfection were also determined by RT-qPCR and Western Blot (WB). Our results showed that expression level of PDHX was significantly increased during sperm transit from epididymal caput to corpus and cauda. Similarly, expression of PDHX was significantly higher (P < 0.05) in fresh sperm as compared to epididymal cauda and frozen-thawed sperm. However, the expression of miR-26a in epididymal corpus sperm was significantly higher (P < 0.05) than that of caput and cauda sperm. Furthermore, after transfection of boar sperm with miR-26a mimic and inhibitor under liquid storage, the lowest and highest sperm viability was observed in miR-26a mimic and inhibitor treatment (P < 0.05), respectively. The protein levels of PDHX, after 24 and 48 h of transfection of miR-26a mimics and inhibitor, were notably decreased and increased (P < 0.05), respectively, as compared to negative control (NC) group. In conclusion, the novel and enticing findings of our study provide a reasonable evidence that miR-26a via PDHX, a link between glycolysis and oxidative phosphorylation, could regulate the glycometabolic pathway which eventually affect boar sperm viability and survival.
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Affiliation(s)
- Wencan Wang
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Kai Liang
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Yu Chang
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Mingxia Ran
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Yan Zhang
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Malik Ahsan Ali
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
- Department of Theriogenology, Riphah College of Veterinary Sciences, Lahore 54000, Pakistan
| | - Dinghui Dai
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Izhar Hyder Qazi
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
- Department of Veterinary Anatomy & Histology, Shaheed Benazir Bhutto University of Veterinary and Animal Sciences, Sakrand 67210, Pakistan
| | - Ming Zhang
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Guangbin Zhou
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Jiandong Yang
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
| | - Christiana Angel
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China;
- Department of Veterinary Parasitology, Faculty of Veterinary Sciences, Shaheed Benazir Bhutto University of Veterinary and Animal Sciences, Sakrand 67210, Pakistan
| | - Changjun Zeng
- College of Animal Sciences and Technology, and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; (W.W.); (K.L.); (Y.C.); (M.R.); (Y.Z.); (M.A.A.); (D.D.); (I.H.Q.); (M.Z.); (G.Z.); (J.Y.)
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4
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Golias T, Kery M, Radenkovic S, Papandreou I. Microenvironmental control of glucose metabolism in tumors by regulation of pyruvate dehydrogenase. Int J Cancer 2018; 144:674-686. [PMID: 30121950 DOI: 10.1002/ijc.31812] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 07/13/2018] [Accepted: 08/06/2018] [Indexed: 12/13/2022]
Abstract
During malignant progression cancer cells undergo a series of changes, which promote their survival, invasiveness and metastatic process. One of them is a change in glucose metabolism. Unlike normal cells, which mostly rely on the tricarboxylic acid cycle (TCA), many cancer types rely on glycolysis. Pyruvate dehydrogenase complex (PDC) is the gatekeeper enzyme between these two pathways and is responsible for converting pyruvate to acetyl-CoA, which can then be processed further in the TCA cycle. Its activity is regulated by PDP (pyruvate dehydrogenase phosphatases) and PDHK (pyruvate dehydrogenase kinases). Pyruvate dehydrogenase kinase exists in 4 tissue specific isoforms (PDHK1-4), the activities of which are regulated by different factors, including hormones, hypoxia and nutrients. PDHK1 and PDHK3 are active in the hypoxic tumor microenvironment and inhibit PDC, resulting in a decrease of mitochondrial function and activation of the glycolytic pathway. High PDHK1/3 expression is associated with worse prognosis in patients, which makes them a promising target for cancer therapy. However, a better understanding of PDC's enzymatic regulation in vivo and of the mechanisms of PDHK-mediated malignant progression is necessary for the design of better PDHK inhibitors and the selection of patients most likely to benefit from such inhibitors.
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Affiliation(s)
- Tereza Golias
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Martin Kery
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Silvia Radenkovic
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Ioanna Papandreou
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center and Wexner Medical Center, Columbus, OH
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Drakulic S, Rai J, Petersen SV, Golas MM, Sander B. Folding and assembly defects of pyruvate dehydrogenase deficiency-related variants in the E1α subunit of the pyruvate dehydrogenase complex. Cell Mol Life Sci 2018; 75:3009-3026. [PMID: 29445841 PMCID: PMC11105750 DOI: 10.1007/s00018-018-2775-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 01/31/2018] [Accepted: 02/06/2018] [Indexed: 12/18/2022]
Abstract
The pyruvate dehydrogenase complex (PDC) bridges glycolysis and the citric acid cycle. In human, PDC deficiency leads to severe neurodevelopmental delay and progressive neurodegeneration. The majority of cases are caused by variants in the gene encoding the PDC subunit E1α. The molecular effects of the variants, however, remain poorly understood. Using yeast as a eukaryotic model system, we have studied the substitutions A189V, M230V, and R322C in yeast E1α (corresponding to the pathogenic variants A169V, M210V, and R302C in human E1α) and evaluated how substitutions of single amino acid residues within different functional E1α regions affect PDC structure and activity. The E1α A189V substitution located in the heterodimer interface showed a more compact conformation with significant underrepresentation of E1 in PDC and impaired overall PDC activity. The E1α M230V substitution located in the tetramer and heterodimer interface showed a relatively more open conformation and was particularly affected by low thiamin pyrophosphate concentrations. The E1α R322C substitution located in the phosphorylation loop of E1α resulted in PDC lacking E3 subunits and abolished overall functional activity. Furthermore, we show for the E1α variant A189V that variant E1α accumulates in the Hsp60 chaperonin, but can be released upon ATP supplementation. Our studies suggest that pathogenic E1α variants may be associated with structural changes of PDC and impaired folding of E1α.
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Affiliation(s)
- Srdja Drakulic
- Department of Biomedicine, Aarhus University, 8000, Aarhus C, Denmark
| | - Jay Rai
- Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, 8000, Aarhus C, Denmark
| | | | - Monika M Golas
- Department of Biomedicine, Aarhus University, 8000, Aarhus C, Denmark.
- Department of Human Genetics, Hannover Medical School, 30625 Hannover, Germany.
| | - Bjoern Sander
- Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, 8000, Aarhus C, Denmark.
- Institute of Pathology, Hannover Medical School, 30625 Hannover, Germany.
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Abstract
The family of 2-oxoacid dehydrogenase complexes (2-OADC), typified by the pyruvate dehydrogenase multi-enzyme complex (PDC) as its most prominent member, are massive molecular machines (Mr, 4-10 million) controlling key steps in glucose homeostasis (PDC), citric acid cycle flux (OGDC, 2-oxoglutarate dehydrogenase) and the metabolism of the branched-chain amino acids, leucine, isoleucine and valine (BCOADC, branched-chain 2-OADC). These highly organised mitochondrial arrays, composed of multiple copies of three separate enzymes, have been widely studied as paradigms for the analysis of enzyme cooperativity, substrate channelling, protein-protein interactions and the regulation of activity by phosphorylation . This chapter will highlight recent advances in our understanding of the structure-function relationships, the overall organisation and the transport and assembly of PDC in particular, focussing on both native and recombinant forms of the complex and their individual components or constituent domains. Biophysical approaches, including X-ray crystallography (MX), nuclear magnetic resonance spectroscopy (NMR), cryo-EM imaging, analytical ultracentrifugation (AUC) and small angle X-ray and neutron scattering (SAXS and SANS), have all contributed significant new information on PDC subunit organisation, stoichiometry, regulatory mechanisms and mode of assembly. Moreover, the recognition of specific genetic defects linked to PDC deficiency, in combination with the ability to analyse recombinant PDCs housing both novel naturally-occurring and engineered mutations, have all stimulated renewed interest in these classical metabolic assemblies. In addition, the role played by PDC, and its constituent proteins, in certain disease states will be briefly reviewed, focussing on the development of new and exciting areas of medical and immunological research.
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Affiliation(s)
- Olwyn Byron
- School of Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - John Gordon Lindsay
- Institute of Molecular, Cell and Systems Biology, Davidson Building, College of Medicine, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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7
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Ivanov IS, Azmanov DN, Ivanova MB, Chamova T, Pacheva IH, Panova MV, Song S, Morar B, Yordanova RV, Galabova FK, Sotkova IG, Linev AJ, Bitchev S, Shearwood AMJ, Kancheva D, Gabrikova D, Karcagi V, Guergueltcheva V, Geneva IE, Bozhinova V, Stoyanova VK, Kremensky I, Jordanova A, Savov A, Horvath R, Brown MA, Tournev I, Filipovska A, Kalaydjieva L. Founder p.Arg 446* mutation in the PDHX gene explains over half of cases with congenital lactic acidosis in Roma children. Mol Genet Metab 2014; 113:76-83. [PMID: 25087164 DOI: 10.1016/j.ymgme.2014.07.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 02/04/2023]
Abstract
Investigation of 31 of Roma patients with congenital lactic acidosis (CLA) from Bulgaria identified homozygosity for the R446* mutation in the PDHX gene as the most common cause of the disorder in this ethnic group. It accounted for around 60% of patients in the study and over 25% of all CLA cases referred to the National Genetic Laboratory in Bulgaria. The detection of a homozygous patient from Hungary and carriers among population controls from Romania and Slovakia suggests a wide spread of the mutation in the European Roma population. The clinical phenotype of the twenty R446* homozygotes was relatively homogeneous, with lactic acidosis crisis in the first days or months of life as the most common initial presentation (15/20 patients) and delayed psychomotor development and/or seizures in infancy as the leading manifestations in a smaller group (5/20 patients). The subsequent clinical picture was dominated by impaired physical growth and a very consistent pattern of static cerebral palsy-like encephalopathy with spasticity and severe to profound mental retardation seen in over 80% of cases. Most patients had a positive family history. We propose testing for the R446* mutation in PDHX as a rapid first screening in Roma infants with metabolic acidosis. It will facilitate and accelerate diagnosis in a large proportion of cases, allow early rehabilitation to alleviate the chronic clinical course, and prevent further affected births in high-risk families.
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Affiliation(s)
- Ivan S Ivanov
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Dimitar N Azmanov
- Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, Australia; Department of Diagnostic Genomics, PathWest, Perth, Australia
| | | | | | - Ilyana H Pacheva
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Margarita V Panova
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Sharon Song
- The University of Queensland Diamantina Institute, Translational Research Institute, Princess Alexandra Hospital, Brisbane, Australia
| | - Bharti Morar
- Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, Australia
| | - Ralitsa V Yordanova
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Fani K Galabova
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Iglika G Sotkova
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Alexandar J Linev
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Stoyan Bitchev
- National Genetic Laboratory, Medical University-Sofia, Bulgaria
| | - Anne-Marie J Shearwood
- Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, Australia
| | - Dalia Kancheva
- Molecular Neurogenomics Group, Department of Molecular Genetics, VIB, University of Antwerp, Belgium; Department of Medical Chemistry and Biochemistry, Molecular Medicine Centre, Medical University-Sofia, Bulgaria
| | - Dana Gabrikova
- Department of Biology, Faculty of Humanities and Natural Sciences, University of Presov, Slovakia
| | - Veronika Karcagi
- Department of Molecular Genetics and Diagnostics, NIEH, Budapest, Hungary
| | | | - Ina E Geneva
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | | | - Vili K Stoyanova
- Department of Pediatrics and Medical Genetics, Plovdiv Medical University, Bulgaria
| | - Ivo Kremensky
- National Genetic Laboratory, Medical University-Sofia, Bulgaria
| | - Albena Jordanova
- Molecular Neurogenomics Group, Department of Molecular Genetics, VIB, University of Antwerp, Belgium; Department of Medical Chemistry and Biochemistry, Molecular Medicine Centre, Medical University-Sofia, Bulgaria
| | - Aleksey Savov
- National Genetic Laboratory, Medical University-Sofia, Bulgaria
| | - Rita Horvath
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Matthew A Brown
- The University of Queensland Diamantina Institute, Translational Research Institute, Princess Alexandra Hospital, Brisbane, Australia
| | - Ivailo Tournev
- Department of Neurology, Medical University-Sofia, Bulgaria; Department of Cognitive Science and Psychology, New Bulgarian University, Sofia, Bulgaria
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, Australia; School of Chemistry and Biochemistry, The University of Western Australia, Perth, Australia
| | - Luba Kalaydjieva
- Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, Australia.
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DeBrosse SD, Okajima K, Zhang S, Nakouzi G, Schmotzer CL, Lusk-Kopp M, Frohnapfel MB, Grahame G, Kerr DS. Spectrum of neurological and survival outcomes in pyruvate dehydrogenase complex (PDC) deficiency: lack of correlation with genotype. Mol Genet Metab 2012; 107:394-402. [PMID: 23021068 DOI: 10.1016/j.ymgme.2012.09.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 08/31/2012] [Accepted: 09/01/2012] [Indexed: 10/27/2022]
Abstract
Pyruvate dehydrogenase complex (PDC) deficiency is a relatively common mitochondrial disorder that primarily presents with neurological manifestations and lactic acidemia. We analyzed the clinical outcomes and neurological features of 59 consented symptomatic subjects (27 M, 32 F), who were confirmed to have PDC deficiency with defined mutations in one of the genes of PDC (PDHA1, n = 53; PDHB, n = 4; DLAT, n = 2), including 47 different mutations, of which 22 were novel, and for whom clinical records and/or structured interviews were obtained. 39% of these subjects (23/59) have died. Of these, 91% (21/23) died before age 4 years, 61% (14/23) before 1 year, and 43% (10/23) before 3 months. 56% of males died compared with 25% of females. Causes of death included severe lactic acidosis, respiratory failure, and infection. In subjects surviving past 6 months, a broad range of intellectual outcomes was observed. Of 42 subjects whose intellectual abilities were professionally evaluated, 19% had normal or borderline intellectual ability (CQ/IQ ≥ 70), 10% had mild intellectual disability (ID) (CQ/IQ 55-69), 17% had moderate ID (CQ/IQ 40-54), 24% had severe ID (CQ/IQ 25-39) and 33% had profound ID (CQ/IQ<25). Assessment by parents was comparable. Of 10 subjects who reached age 12 years, 9 had had professional IQ assessments, and only 4 had IQs ≥ 70 (only 2 of these 4 had assessments after age 12 years). The average outcome for females was severe-to-profound ID, whereas that of males was mild-to-moderate ID. Of subjects for whom specific neurological data were available, the majority had hypotonia (89%), and hypertonia or mixed hyper-/hypotonia (49%) were common. Seizures (57%), microcephaly (49%), and structural brain abnormalities including ventriculomegaly (67%) and agenesis, dysgenesis, or hypoplasia of the corpus callosum (55%) were common. Leigh syndrome was found in only 35%. Structural brain abnormalities were more common in females, and Leigh syndrome was more common in males. In a subgroup of 16 ambulatory subjects >3.5 years in whom balance was evaluated, ataxia was found in 13. Peripheral neuropathy was documented in 2 cases but not objectively evaluated in most subjects. Outcomes of this population with genetically confirmed PDC deficiency are heterogeneous and not distinctive. Correlations between specific genotypes and outcomes were not established. Although more females survive, related to the prevalence of X-linked PDHA1 mutations, symptomatic surviving females are generally more severely impaired cognitively and have a different pattern of neurological impairment compared to males. Neonatal or infant onset of symptoms was associated with poor outcomes. Males with PDHA1 mutations and low fibroblast PDC activity were less likely to survive beyond infancy. Recurrence rate in siblings of subjects with PDHA1 mutation was less than 5%. Paradoxically, in this retrospective review, potential factors considered possibly relevant to development, such as in vitro PDC activity, specific mutations, use of ketogenic diets, supplements, or medications, were generally not confirmed to be significantly correlated with objective outcomes of survival or neuro-cognitive function. Therefore, the basis of variability of these outcomes remains largely undetermined.
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Pyruvate dehydrogenase deficiency caused by a new mutation of PDHX gene in two Moroccan patients. Eur J Med Genet 2012; 55:535-40. [PMID: 22766002 DOI: 10.1016/j.ejmg.2012.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Accepted: 06/12/2012] [Indexed: 11/21/2022]
Abstract
Pyruvate dehydrogenase deficiency is one of the genetic defects of mitochondrial energy metabolism. Clinical features are heterogeneous, ranging from fatal lactic acidosis in the newborn period to chronic neurodegenerative abnormalities. Most cases have mutations in the gene for the E1alpha subunit of the pyruvate dehydrogenase complex. Primary defects of the E3 binding protein component of the pyruvate dehydrogenase complex are rarier. We describe two unrelated Moroccan patients with the same new mutation c.1182 + 2T > C in the E3 binding protein gene PDHX and different clinical forms.
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Patel KP, O’Brien TW, Subramony SH, Shuster J, Stacpoole PW. The spectrum of pyruvate dehydrogenase complex deficiency: clinical, biochemical and genetic features in 371 patients. Mol Genet Metab 2012; 106:385-94. [PMID: 22896851 PMCID: PMC4003492 DOI: 10.1016/j.ymgme.2012.03.017] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
CONTEXT Pyruvate dehydrogenase complex (PDC) deficiency is a genetic mitochondrial disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration and, usually, death during childhood. There has been no recent comprehensive analysis of the natural history and clinical course of this disease. OBJECTIVE We reviewed 371 cases of PDC deficiency, published between 1970 and 2010, that involved defects in subunits E1α and E1β and components E1, E2, E3 and the E3 binding protein of the complex. DATA SOURCES AND EXTRACTION English language peer-reviewed publications were identified, primarily by using PubMed and Google Scholar search engines. RESULTS Neurodevelopmental delay and hypotonia were the commonest clinical signs of PDC deficiency. Structural brain abnormalities frequently included ventriculomegaly, dysgenesis of the corpus callosum and neuroimaging findings typical of Leigh syndrome. Neither gender nor any clinical or neuroimaging feature differentiated the various biochemical etiologies of the disease. Patients who died were younger, presented clinically earlier and had higher blood lactate levels and lower residual enzyme activities than subjects who were still alive at the time of reporting. Survival bore no relationship to the underlying biochemical or genetic abnormality or to gender. CONCLUSIONS Although the clinical spectrum of PDC deficiency is broad, the dominant clinical phenotype includes presentation during the first year of life; neurological and neuromuscular degeneration; structural lesions revealed by neuroimaging; lactic acidosis and a blood lactate:pyruvate ratio ≤ 20.
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Affiliation(s)
- Kavi P. Patel
- Department of Medicine (Division of Endocrinology, Metabolism and
Diabetes), College of Medicine, University of Florida, Gainesville, FL 32611,
USA
| | - Thomas W. O’Brien
- Department of Biochemistry and Molecular Biology, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
| | | | - Jonathan Shuster
- Department of Epidemiology and Health Policy Research, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Peter W. Stacpoole
- Department of Medicine (Division of Endocrinology, Metabolism and
Diabetes), College of Medicine, University of Florida, Gainesville, FL 32611,
USA
- Department of Biochemistry and Molecular Biology, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
- Corresponding author at: UF College of Medicine, 1600 SW
Archer Road M2-238, P.O. Box 100226, Gainesville, FL 32610, USA. Fax: +1
352 273 9013. (P.W. Stacpoole)
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Patel KP, O'Brien TW, Subramony SH, Shuster J, Stacpoole PW. The spectrum of pyruvate dehydrogenase complex deficiency: clinical, biochemical and genetic features in 371 patients. Mol Genet Metab 2012; 105:34-43. [PMID: 22079328 PMCID: PMC3754811 DOI: 10.1016/j.ymgme.2011.09.032] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 09/27/2011] [Accepted: 09/27/2011] [Indexed: 01/01/2023]
Abstract
CONTEXT Pyruvate dehydrogenase complex (PDC) deficiency is a genetic mitochondrial disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration and, usually, death during childhood. There has been no recent comprehensive analysis of the natural history and clinical course of this disease. OBJECTIVE We reviewed 371 cases of PDC deficiency, published between 1970 and 2010, that involved defects in subunits E1α and E1β and components E1, E2, E3 and the E3 binding protein of the complex. DATA SOURCES AND EXTRACTION English language peer-reviewed publications were identified, primarily by using PubMed and Google Scholar search engines. RESULTS Neurodevelopmental delay and hypotonia were the commonest clinical signs of PDC deficiency. Structural brain abnormalities frequently included ventriculomegaly, dysgenesis of the corpus callosum and neuroimaging findings typical of Leigh syndrome. Neither gender nor any clinical or neuroimaging feature differentiated the various biochemical etiologies of the disease. Patients who died were younger, presented clinically earlier and had higher blood lactate levels and lower residual enzyme activities than subjects who were still alive at the time of reporting. Survival bore no relationship to the underlying biochemical or genetic abnormality or to gender. CONCLUSIONS Although the clinical spectrum of PDC deficiency is broad, the dominant clinical phenotype includes presentation during the first year of life; neurological and neuromuscular degeneration; structural lesions revealed by neuroimaging; lactic acidosis and a blood lactate:pyruvate ratio ≤20.
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Affiliation(s)
- Kavi P. Patel
- Department of Medicine (Division of Endocrinology and Metabolism), College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Thomas W. O'Brien
- Department of Biochemistry and Molecular Biology College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | | | - Jonathan Shuster
- Epidemiology and Health Policy Research College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Peter W. Stacpoole
- Department of Medicine (Division of Endocrinology and Metabolism), College of Medicine, University of Florida, Gainesville, FL, 32611, USA
- Department of Biochemistry and Molecular Biology College of Medicine, University of Florida, Gainesville, FL, 32611, USA
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Imbard A, Boutron A, Vequaud C, Zater M, de Lonlay P, de Baulny HO, Barnerias C, Miné M, Marsac C, Saudubray JM, Brivet M. Molecular characterization of 82 patients with pyruvate dehydrogenase complex deficiency. Structural implications of novel amino acid substitutions in E1 protein. Mol Genet Metab 2011; 104:507-16. [PMID: 21914562 DOI: 10.1016/j.ymgme.2011.08.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Revised: 08/10/2011] [Accepted: 08/10/2011] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pyruvate dehydrogenase complex (PDHc) deficiencies are an important cause of primary lactic acidosis. Most cases result from mutations in the X-linked gene for the pyruvate dehydrogenase E1α subunit (PDHA1) while a few cases result from mutations in genes for E1β (PDHB), E2 (DLAT), E3 (DLD) and E3BP (PDHX) subunits or PDH-phosphatase (PDP1). AIM To report molecular characterization of 82 PDHc-deficient patients and analyze structural effects of novel missense mutations in PDHA1. METHODS PDHA1 variations were investigated first, by exon sequencing using a long range PCR product, gene dosage assay and cDNA analysis. Mutation scanning in PDHX, PDHB, DLAT and DLD cDNAs was further performed in unsolved cases. Novel missense mutations in PDHA1 were located on the tridimensional model of human E1 protein to predict their possible functional consequences. RESULTS PDHA1 mutations were found in 30 girls and 35 boys. Three large rearrangements, including two contiguous gene deletion syndrome were identified. Novel missense, frameshift and splicing mutations were also delineated and a nonsense mutation in a mosaic male. Mutations p.Glu75Ala, p.Arg88Ser, p.Arg119Trp, p.Gly144Asp, p.Pro217Arg, p.Arg235Gly, p.Tyr243Cys, p.Tyr243Ser, p.Arg245Gly, p.Pro250Leu, p.Gly278Arg, p.Met282Val, p.Gly298Glu in PDHA1 were predicted to impair active site channel conformation or subunit interactions. Six out of the seven patients with PDHB mutations displayed the recurrent p.Met101Val mutation; 9 patients harbored PDHX mutations and one patient DLD mutations. CONCLUSION We provide an efficient stepwise strategy for mutation screening in PDHc genes and expand the growing list of PDHA1 mutations analyzed at the structural level.
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Affiliation(s)
- A Imbard
- Biochimie-Hôpital de Bicêtre, Hôpitaux Universitaires Paris-Sud, AP-HP, Paris, France
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Abstract
Chorea is a common movement disorder that can be caused by a large variety of structural, neurochemical (including pharmacologic), or metabolic disturbances to basal ganglia function, indicating the vulnerability of this brain region. The diagnosis is rarely indicated by the simple phenotypic appearance of chorea, and can be challenging, with many patients remaining undiagnosed. Clues to diagnosis may be found in the patient's family or medical history, on neurologic examination, or upon laboratory testing and neuroimaging. Increasingly, advances in genetic medicine are identifying new disorders and expanding the phenotype of recognized conditions. Although most therapies at present are supportive, correct diagnosis is essential for appropriate genetic counseling, and ultimately, for future molecular therapies.
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Affiliation(s)
- Ruth H Walker
- Department of Neurology, James J. Peters Veterans Affairs Medical Center, Bronx, NY 10468, USA.
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Miller JA, Runkle SA, Tjalkens RB, Philbert MA. 1,3-Dinitrobenzene-induced metabolic impairment through selective inactivation of the pyruvate dehydrogenase complex. Toxicol Sci 2011; 122:502-11. [PMID: 21551353 DOI: 10.1093/toxsci/kfr102] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Prolonged exposure to the chemical intermediate, 1,3-dinitrobenzene (1,3-DNB), produces neuropathology in the central nervous system of rodents analogous to that observed in various conditions of acute energy deprivation including thiamine deficiency and Leigh's necrotizing encephalopathy. Increased production of reactive intermediates in addition to induction of oxidative stress has been implicated in the neurotoxic mechanism of 1,3-DNB, but a clear metabolic target has not been determined. Here we propose that similar to thiamine deficiency, the effects of 1,3-DNB on metabolic status may be due to inhibition of the thiamine-dependent α-ketoacid dehydrogenase complexes. The effects of 1,3-DNB on astroglial metabolic status and α-ketoacid dehydrogenase activity were evaluated using rat C6 glioma cells. Exposure to 1,3-DNB resulted in altered morphology and biochemical dysfunction consistent with disruption of oxidative energy metabolism. Cotreatment with acetyl-carnitine or acetoacetate attenuated morphological and metabolic effects of 1,3-DNB exposure as well as increased cell viability. 1,3-DNB exposure inhibited pyruvate dehydrogenase complex (PDHc) and the inhibition correlated with the loss of lipoic acid (LA) immunoreactivity, suggesting that modification of LA is a potential mechanism of inhibition. Treatment with antioxidants and thiol-containing compounds failed to protect against loss of LA. Alternatively, inhibition of dihydrolipoamide dehydrogenase, the E3 component of the complex attenuated loss of LA. Collectively, these data suggest that 1,3-DNB impairs oxidative energy metabolism through direct inhibition of the PDHc and that this impairment is due to perturbations in the function of protein-bound LA.
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Affiliation(s)
- James A Miller
- Center for Environmental Medicine, Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
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Quintana E, Gort L, Busquets C, Navarro-Sastre A, Lissens W, Moliner S, Lluch M, Vilaseca MA, De Meirleir L, Ribes A, Briones P. Mutational study in thePDHA1gene of 40 patients suspected of pyruvate dehydrogenase complex deficiency. Clin Genet 2010; 77:474-82. [DOI: 10.1111/j.1399-0004.2009.01313.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Barnerias C, Saudubray JM, Touati G, De Lonlay P, Dulac O, Ponsot G, Marsac C, Brivet M, Desguerre I. Pyruvate dehydrogenase complex deficiency: four neurological phenotypes with differing pathogenesis. Dev Med Child Neurol 2010; 52:e1-9. [PMID: 20002125 DOI: 10.1111/j.1469-8749.2009.03541.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To describe the phenotype and genotype of pyruvate dehydrogenase complex (PDHc) deficiency. METHOD Twenty-two participants with enzymologically and genetically confirmed PDHc deficiency were analysed for clinical and imaging features over a 15-year period. RESULTS Four groups were identified: (1) those with neonatal encephalopathy with lactic acidosis (one male, four females; diagnosis at birth); (2) those with non-progressive infantile encephalopathy (three males, three females; age at diagnosis 2-9mo); (3) those with Leigh syndrome (eight males; age at diagnosis 1-13mo); and (4) those with relapsing ataxia (three males; 18-30mo). Seventeen mutations involved PDHA1 (a hotspot was identified in exons 6, 7, and 8 in seven males with Leigh syndrome or recurrent ataxia). Mutations in the PDHX gene (five cases) were correlated with non-progressive encephalopathy and long-term survival in four cases. INTERPRETATION Two types of neurological involvement were identified. Abnormal prenatal brain development resulted in severe non-progressive encephalopathy with callosal agenesis, gyration anomalies, microcephaly with intrauterine growth retardation, or dysmorphia in both males and females (12 cases). Acute energy failure in infant life produced basal ganglia lesions with paroxysmal dystonia, neuropathic ataxia due to axonal transport dysfunction, or epilepsy only in males (11 cases). The ketogenic diet improved only paroxysmal dysfunction, providing an additional argument in favour of paroxysmal energy failure.
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Han Z, Zhong L, Srivastava A, Stacpoole PW. Pyruvate dehydrogenase complex deficiency caused by ubiquitination and proteasome-mediated degradation of the E1 subunit. J Biol Chem 2007; 283:237-243. [PMID: 17923481 DOI: 10.1074/jbc.m704748200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Congenital deficiencies of the human pyruvate dehydrogenase (PDH) complex are considered to be due to loss of function mutations in one of the component enzymes. Here we describe a case of PDH deficiency associated with the PDH E1beta subunit (PDHB) gene. The clinical phenotype of the patient was consistent with reported cases of PDH deficiency. Cultured skin fibroblasts demonstrated a 55% reduction in PDH activity and markedly decreased immunoreactivity for PDHB protein, compared with healthy controls. Surprisingly, nucleotide sequence analyses of cDNAs corresponding to the patient PDH E1alpha (PDHA1) and PDHB genes revealed no pathological mutations. Moreover, the relative expression level of PDHB mRNA and the rates of transcription and translation of the PDHB gene were normal. However, PDC activity could be restored in cells from this patient following treatment with MG132, a specific proteasome inhibitor, and normal levels of E1beta could be detected in MG132-treated cells. Similar results were obtained following treatment with Tyr-phostin 23 (Tyr23), a specific inhibitor of epidermal growth factor receptor-protein-tyrosine kinase (EGFR-PTK), which also restored E1beta protein levels to those in cells from healthy subjects or from patients with PDHA1 deficiency. The index patient's cells contained a high basal level of EGFR-PTK activity that correlated with the high level of ubiquitination of cellular proteins, although the total EGFR protein levels were similar to those in cells from Elalpha-deficient subjects and healthy subjects. These data indicate that PDH deficiency in our patient involves a post-translational modification in which EGFR-PTK-mediated tyrosine phosphorylation of the E1beta protein leads to enhanced ubiquitination followed by proteasome-mediated degradation. They also provide a novel mechanism accounting for congenital deficiency of the PDH complex and perhaps other inborn errors of metabolism.
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Affiliation(s)
- Zongchao Han
- Departments of Pediatrics, Division of Cellular and Molecular Therapy, Gainesville, Florida 32610
| | - Li Zhong
- Departments of Pediatrics, Division of Cellular and Molecular Therapy, Gainesville, Florida 32610
| | - Arun Srivastava
- Departments of Pediatrics, Division of Cellular and Molecular Therapy, Gainesville, Florida 32610; Molecular Genetics and Microbiology, Gainesville, Florida 32610; The General Clinical Research Center, Gainesville, Florida 32610
| | - Peter W Stacpoole
- The General Clinical Research Center, Gainesville, Florida 32610; Medicine, Division of Endocrinology and Metabolism, Gainesville, Florida 32610; Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida 32610.
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18
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Miné M, Chen JM, Brivet M, Desguerre I, Marchant D, de Lonlay P, Bernard A, Férec C, Abitbol M, Ricquier D, Marsac C. A large genomic deletion in the PDHX gene caused by the retrotranspositional insertion of a full-length LINE-1 element. Hum Mutat 2007; 28:137-42. [PMID: 17152059 DOI: 10.1002/humu.20449] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The long interspersed element-1 (LINE-1 or L1) retrotransposition has altered the human genome in many ways. In particular, recent in vitro studies have demonstrated that the retrotranspositional insertion of L1 elements has resulted in significant genomic deletions. Here we provide evidence for its operation in the human genome by identifying a approximately 46-kb pathological genomic deletion in the PDHX gene directly linked to the insertion of a full-length L1 element, in a patient with pyruvate dehydrogenase complex (PDHc) deficiency. Both the deduced bottom and top strand cleavage sites in the PDHX gene coincide with the consensus L1 endonuclease (EN) target sequence 5'-TTTT/A-3', while the full-length L1 element is followed by a 67-bp poly(A) tail. Interestingly, two hairpin structures, potentially formed by the inverted repeats present immediately 5' to the top strand nick site and 3' to the bottom strand nick site, may have facilitated the accessibility of L1 EN to the target sequences and also brought the two otherwise distantly located sequences into close proximity. Since the L1 element inserted in the PDHX gene is full-length, we favor the model of the template jumping as opposed to that of the microhomology-mediated end-joining for linking the 5' end of the nascent L1 copy to its genomic target. Our finding not only serves as an important complement to the in vitro approaches to studying L1 retrotransposition, but also reveals a novel mechanism causing human genetic disease.
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Affiliation(s)
- Manuèle Miné
- Centre de Recherches Thérapeutiques en Ophtalmologie, Faculté de Médecine Necker, Paris, France
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