1
|
Li YM, He HW, Zhang N. Targeting Protein Phosphatases for the Treatment of Chronic Liver Disease. Curr Drug Targets 2024; 25:171-189. [PMID: 38213163 DOI: 10.2174/0113894501278886231221092522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 01/13/2024]
Abstract
There exists a huge number of patients suffering from chronic liver disease worldwide. As a disease with high incidence and mortality worldwide, strengthening the research on the pathogenesis of chronic liver disease and the development of novel drugs is an important issue related to the health of all human beings. Phosphorylation modification of proteins plays a crucial role in cellular signal transduction, and phosphatases are involved in the development of liver diseases. Therefore, this article summarized the important role of protein phosphatases in chronic liver disease with the aim of facilitating the development of drugs targeting protein phosphatases for the treatment of chronic liver disease.
Collapse
Affiliation(s)
- Yi-Ming Li
- NHC Key Laboratory of Biotechnology for Microbial Drugs, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100050, China
| | - Hong-Wei He
- NHC Key Laboratory of Biotechnology for Microbial Drugs, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100050, China
| | - Na Zhang
- NHC Key Laboratory of Biotechnology for Microbial Drugs, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100050, China
| |
Collapse
|
2
|
Szabo E, Nagy B, Czajlik A, Komlodi T, Ozohanics O, Tretter L, Ambrus A. Mitochondrial Alpha-Keto Acid Dehydrogenase Complexes: Recent Developments on Structure and Function in Health and Disease. Subcell Biochem 2024; 104:295-381. [PMID: 38963492 DOI: 10.1007/978-3-031-58843-3_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
The present work delves into the enigmatic world of mitochondrial alpha-keto acid dehydrogenase complexes discussing their metabolic significance, enzymatic operation, moonlighting activities, and pathological relevance with links to underlying structural features. This ubiquitous family of related but diverse multienzyme complexes is involved in carbohydrate metabolism (pyruvate dehydrogenase complex), the citric acid cycle (α-ketoglutarate dehydrogenase complex), and amino acid catabolism (branched-chain α-keto acid dehydrogenase complex, α-ketoadipate dehydrogenase complex); the complexes all function at strategic points and also participate in regulation in these metabolic pathways. These systems are among the largest multienzyme complexes with at times more than 100 protein chains and weights ranging up to ~10 million Daltons. Our chapter offers a wealth of up-to-date information on these multienzyme complexes for a comprehensive understanding of their significance in health and disease.
Collapse
Affiliation(s)
- Eszter Szabo
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Balint Nagy
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Andras Czajlik
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Timea Komlodi
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Oliver Ozohanics
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Laszlo Tretter
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Attila Ambrus
- Department of Biochemistry, Semmelweis University, Budapest, Hungary.
| |
Collapse
|
3
|
Stacpoole PW, McCall CE. The pyruvate dehydrogenase complex: Life's essential, vulnerable and druggable energy homeostat. Mitochondrion 2023; 70:59-102. [PMID: 36863425 DOI: 10.1016/j.mito.2023.02.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/30/2023] [Accepted: 02/13/2023] [Indexed: 03/04/2023]
Abstract
Found in all organisms, pyruvate dehydrogenase complexes (PDC) are the keystones of prokaryotic and eukaryotic energy metabolism. In eukaryotic organisms these multi-component megacomplexes provide a crucial mechanistic link between cytoplasmic glycolysis and the mitochondrial tricarboxylic acid (TCA) cycle. As a consequence, PDCs also influence the metabolism of branched chain amino acids, lipids and, ultimately, oxidative phosphorylation (OXPHOS). PDC activity is an essential determinant of the metabolic and bioenergetic flexibility of metazoan organisms in adapting to changes in development, nutrient availability and various stresses that challenge maintenance of homeostasis. This canonical role of the PDC has been extensively probed over the past decades by multidisciplinary investigations into its causal association with diverse physiological and pathological conditions, the latter making the PDC an increasingly viable therapeutic target. Here we review the biology of the remarkable PDC and its emerging importance in the pathobiology and treatment of diverse congenital and acquired disorders of metabolic integration.
Collapse
Affiliation(s)
- Peter W Stacpoole
- Department of Medicine (Division of Endocrinology, Metabolism and Diabetes), and Department of Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, FL, United States.
| | - Charles E McCall
- Department of Internal Medicine and Translational Sciences, and Department of Microbiology and Immunology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| |
Collapse
|
4
|
A Missense Variant in PDK1 Associated with Severe Neurodevelopmental Delay and Epilepsy. Biomedicines 2022; 10:biomedicines10123171. [PMID: 36551928 PMCID: PMC9775741 DOI: 10.3390/biomedicines10123171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/02/2022] [Accepted: 12/04/2022] [Indexed: 12/13/2022] Open
Abstract
The pyruvate dehydrogenase complex (PDC) is responsible for the conversion of pyruvate into acetyl-CoA, which is used for energy conversion in cells. PDC activity is regulated by phosphorylation via kinases and phosphatases (PDK/PDP). Variants in all subunits of the PDC and in PDK3 have been reported, with varying phenotypes including lactic acidosis, neurodevelopmental delay, peripheral neuropathy, or seizures. Here, we report a de novo heterozygous missense variant in PDK1 (c.1139G > A; p.G380D) in a girl with developmental delay and early onset severe epilepsy. To investigate the role of PDK1G380D in energy metabolism and neuronal development, we used a zebrafish model. In zebrafish embryos we show a reduced number of cells with mitochondria with membrane potential, reduced movements, and a delay in neuronal development. Furthermore, we observe a reduction in the phosphorylation of PDH-E1α by PDKG380D, which suggests a disruption in the regulation of PDC activity. Finally, in patient fibroblasts, a mild reduction in the ratio of phosphorylated PDH over total PDH-E1α was detected. In summary, our findings support the notion that this aberrant PDK1 activity is the cause of clinical symptoms in the patient.
Collapse
|
5
|
Baker MJ, Crameri JJ, Thorburn DR, Frazier AE, Stojanovski D. Mitochondrial biology and dysfunction in secondary mitochondrial disease. Open Biol 2022; 12:220274. [PMID: 36475414 PMCID: PMC9727669 DOI: 10.1098/rsob.220274] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial diseases are a broad, genetically heterogeneous class of metabolic disorders characterized by deficits in oxidative phosphorylation (OXPHOS). Primary mitochondrial disease (PMD) defines pathologies resulting from mutation of mitochondrial DNA (mtDNA) or nuclear genes affecting either mtDNA expression or the biogenesis and function of the respiratory chain. Secondary mitochondrial disease (SMD) arises due to mutation of nuclear-encoded genes independent of, or indirectly influencing OXPHOS assembly and operation. Despite instances of novel SMD increasing year-on-year, PMD is much more widely discussed in the literature. Indeed, since the implementation of next generation sequencing (NGS) techniques in 2010, many novel mitochondrial disease genes have been identified, approximately half of which are linked to SMD. This review will consolidate existing knowledge of SMDs and outline discrete categories within which to better understand the diversity of SMD phenotypes. By providing context to the biochemical and molecular pathways perturbed in SMD, we hope to further demonstrate the intricacies of SMD pathologies outside of their indirect contribution to mitochondrial energy generation.
Collapse
Affiliation(s)
- Megan J. Baker
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Jordan J. Crameri
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia
| | - David R. Thorburn
- Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia,Victorian Clinical Genetics Services, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Ann E. Frazier
- Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Diana Stojanovski
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia
| |
Collapse
|
6
|
Pan J, Zhou L, Zhang C, Xu Q, Sun Y. Targeting protein phosphatases for the treatment of inflammation-related diseases: From signaling to therapy. Signal Transduct Target Ther 2022; 7:177. [PMID: 35665742 PMCID: PMC9166240 DOI: 10.1038/s41392-022-01038-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/28/2022] [Accepted: 05/25/2022] [Indexed: 11/09/2022] Open
Abstract
Inflammation is the common pathological basis of autoimmune diseases, metabolic diseases, malignant tumors, and other major chronic diseases. Inflammation plays an important role in tissue homeostasis. On one hand, inflammation can sense changes in the tissue environment, induce imbalance of tissue homeostasis, and cause tissue damage. On the other hand, inflammation can also initiate tissue damage repair and maintain normal tissue function by resolving injury and restoring homeostasis. These opposing functions emphasize the significance of accurate regulation of inflammatory homeostasis to ameliorate inflammation-related diseases. Potential mechanisms involve protein phosphorylation modifications by kinases and phosphatases, which have a crucial role in inflammatory homeostasis. The mechanisms by which many kinases resolve inflammation have been well reviewed, whereas a systematic summary of the functions of protein phosphatases in regulating inflammatory homeostasis is lacking. The molecular knowledge of protein phosphatases, and especially the unique biochemical traits of each family member, will be of critical importance for developing drugs that target phosphatases. Here, we provide a comprehensive summary of the structure, the "double-edged sword" function, and the extensive signaling pathways of all protein phosphatases in inflammation-related diseases, as well as their potential inhibitors or activators that can be used in therapeutic interventions in preclinical or clinical trials. We provide an integrated perspective on the current understanding of all the protein phosphatases associated with inflammation-related diseases, with the aim of facilitating the development of drugs that target protein phosphatases for the treatment of inflammation-related diseases.
Collapse
Affiliation(s)
- Jie Pan
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), Department of Biotechnology and Pharmaceutical Sciences, School of Life Science, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China
| | - Lisha Zhou
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), Department of Biotechnology and Pharmaceutical Sciences, School of Life Science, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China
| | - Chenyang Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), Department of Biotechnology and Pharmaceutical Sciences, School of Life Science, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China
| | - Qiang Xu
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), Department of Biotechnology and Pharmaceutical Sciences, School of Life Science, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Yang Sun
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), Department of Biotechnology and Pharmaceutical Sciences, School of Life Science, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China.
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
| |
Collapse
|
7
|
Tokuoka M, Kobayashi K, Lemaire P, Satou Y. Protein kinases and protein phosphatases encoded in the Ciona robusta genome. Genesis 2022; 60:e23471. [PMID: 35261143 DOI: 10.1002/dvg.23471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/24/2022] [Accepted: 02/27/2022] [Indexed: 11/06/2022]
Abstract
Protein kinases (PKs) and protein phosphatases (PPs) regulate the phosphorylation of proteins that are involved in a variety of biological processes. To study such biological processes systematically, it is important to know the whole repertoire of PKs and PPs encoded in a genome. In the present study, we surveyed the genome of an ascidian (Ciona robusta or Ciona intestinalis type A) to comprehensively identify the genes that encoded PKs and PPs. Because ascidians belong to the sister group of vertebrates, a comparison of the whole repertoire of PKs and PPs of ascidians with those of vertebrates may help to delineate the complements of these proteins that were present in the last common ancestor of these two groups of animals. Our results show that the repertory of PPs was much more expanded in vertebrates than the repertory of PKs. We also showed that approximately 75% of PKs and PPs were expressed during development from eggs to larvae. Thus, the present study provides catalogs for PKs and PPs encoded in the ascidian genome. These catalogs will be useful for systematic studies of biological processes that involve phosphorylation and for evolutionary studies of the origin of vertebrates.
Collapse
Affiliation(s)
- Miki Tokuoka
- Institut de Biologie du Développement de Marseille (IBDM), CNRS, Aix-Marseille Université, Marseille, France.,Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Kenji Kobayashi
- Institut de Biologie du Développement de Marseille (IBDM), CNRS, Aix-Marseille Université, Marseille, France.,Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Patrick Lemaire
- Institut de Biologie du Développement de Marseille (IBDM), CNRS, Aix-Marseille Université, Marseille, France.,Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS, Université de Montpellier, Montpellier, France
| | - Yutaka Satou
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| |
Collapse
|
8
|
Hannah-Shmouni F, MacNeil L, Brady L, Nilsson MI, Tarnopolsky M. Expanding the Clinical Spectrum of LONP1-Related Mitochondrial Cytopathy. Front Neurol 2019; 10:981. [PMID: 31636596 PMCID: PMC6787162 DOI: 10.3389/fneur.2019.00981] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 08/28/2019] [Indexed: 12/12/2022] Open
Abstract
Pathogenic variants in the LONP1 gene have been associated with CODAS syndrome (Cerebral, Ocular, Dental, Auricular, and Skeletal Anomalies Syndrome). A recent report identified the first newborn case with LONP1-related mitochondrial cytopathy due to a compound heterozygous pathogenic variant in LONP1 without features of CODAS. The proband had manifested with severe congenital lactic acidosis and profound multiple respiratory chain complex activity deficiencies associated with the quantitative loss of mtDNA copy number in muscle. A subsequent report identified two siblings with regression during infancy, profound hypotonia and muscle weakness, severe intellectual disability, progressive cerebellar atrophy, where muscle biopsy showed an electron dense mitochondrial inclusions without ragged-red fibers and normal electron transport chain enzyme activities. Here, we report an additional case of autosomal recessive mitochondrial cytopathy due to a homozygous missense variant in LONP1 that was identified on whole exome sequencing (c.810G > A; p.D463N). The proband, a 20-year-old male born to consanguineous parents, presented with global developmental delay, emotional outbursts, speech and swallowing difficulties, hypotonia, and ataxia since childhood. Muscle biopsy showed massive granular bodies, increased oxidative stress, and autophagic block and reduced mitochondrial state 3 respiration. We have identified another case of LONP1-related mitochondrial cytopathy further confirming a neurological phenotype without CODAS features.
Collapse
Affiliation(s)
- Fady Hannah-Shmouni
- Clinical Biochemical Genetics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.,Section on Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Lauren MacNeil
- Division of Pediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Lauren Brady
- Department of Pediatrics, McMaster University, Hamilton, ON, Canada
| | - Mats I Nilsson
- Department of Pediatrics, McMaster University, Hamilton, ON, Canada
| | - Mark Tarnopolsky
- Department of Pediatrics, McMaster University, Hamilton, ON, Canada
| |
Collapse
|
9
|
Bedoyan JK, Hecht L, Zhang S, Tarrant S, Bergin A, Demirbas D, Yang E, Shin HK, Grahame GJ, DeBrosse SD, Hoppel CL, Kerr DS, Berry GT. A novel null mutation in the pyruvate dehydrogenase phosphatase catalytic subunit gene ( PDP1) causing pyruvate dehydrogenase complex deficiency. JIMD Rep 2019; 48:26-35. [PMID: 31392110 PMCID: PMC6606986 DOI: 10.1002/jmd2.12054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/21/2019] [Accepted: 05/22/2019] [Indexed: 01/03/2023] Open
Abstract
Congenital lactic acidosis due to pyruvate dehydrogenase phosphatase (PDP) deficiency is very rare. PDP regulates pyruvate dehydrogenase complex (PDC) and defective PDP leads to PDC deficiency. We report a case with functional PDC deficiency with low activated (+dichloroacetate) and inactivated (+fluoride) PDC activities in lymphocytes and fibroblasts, normal activity of other mitochondrial enzymes in fibroblasts, and novel biallelic frameshift mutation in the PDP1 gene, c.575dupT (p.L192FfsX5), with absent PDP1 product in fibroblasts. Unexpectedly, the patient also had low branched-chain 2-ketoacid dehydrogenase (BCKDH) activity in fibroblasts with slight elevation of branched-chain amino acids in plasma and ketoacids in urine but with no pathogenic mutations in the enzymes of BCKDH, which could suggest shared regulatory function of PDC and BCKDH in fibroblasts, potentially in other tissues or cell types as well, but this remains to be determined. The clinical presentation of this patient overlaps that of other patients with primary-specific PDC deficiency, with neonatal/infantile and childhood lactic acidosis, normal lactate to pyruvate ratio, elevated plasma alanine, delayed psychomotor development, epileptic encephalopathy, feeding difficulties, and hypotonia. This patient exhibited marked improvement of overall development following initiation of ketogenic diet at 31 months of age. To the best of our knowledge, this is the fourth case of functional PDC deficiency with a defined mutation in PDP1. SYNOPSIS Pyruvate dehydrogenase phosphatase (PDP) regulates pyruvate dehydrogenase complex (PDC) and defective PDP due to PDP1 mutations leads to PDC deficiency and congenital lactic acidosis.
Collapse
Affiliation(s)
- Jirair K. Bedoyan
- Department of Genetics and Genome SciencesCase Western Reserve University (CWRU)ClevelandOhio
- PediatricsCase Western Reserve University (CWRU)ClevelandOhio
- Center for Human GeneticsUniversity Hospitals Cleveland Medical Center (UHCMC)ClevelandOhio
- Center for Inherited Disorders of Energy Metabolism (CIDEM)University Hospitals Cleveland Medical Center (UHCMC)ClevelandOhio
| | - Leah Hecht
- Division of Genetics and Genomics, The Manton Center for Orphan Disease ResearchBoston Children's Hospital, Harvard Medical SchoolBostonMassachusetts
| | - Shulin Zhang
- Pathology and Laboratory MedicineUniversity of KentuckyLexingtonKentucky
| | - Stacey Tarrant
- Division of Genetics and Genomics, The Manton Center for Orphan Disease ResearchBoston Children's Hospital, Harvard Medical SchoolBostonMassachusetts
| | - Ann Bergin
- Department of NeurologyBoston Children's Hospital, Harvard Medical SchoolBostonMassachusetts
| | - Didem Demirbas
- Division of Genetics and Genomics, The Manton Center for Orphan Disease ResearchBoston Children's Hospital, Harvard Medical SchoolBostonMassachusetts
| | - Edward Yang
- RadiologyBoston Children's Hospital, Harvard Medical SchoolBostonMassachusetts
| | - Ha Kyung Shin
- School of MedicineCase Western Reserve University (CWRU)ClevelandOhio
| | - George J. Grahame
- Center for Inherited Disorders of Energy Metabolism (CIDEM)University Hospitals Cleveland Medical Center (UHCMC)ClevelandOhio
| | - Suzanne D. DeBrosse
- Department of Genetics and Genome SciencesCase Western Reserve University (CWRU)ClevelandOhio
- PediatricsCase Western Reserve University (CWRU)ClevelandOhio
- Center for Human GeneticsUniversity Hospitals Cleveland Medical Center (UHCMC)ClevelandOhio
| | - Charles L. Hoppel
- Center for Inherited Disorders of Energy Metabolism (CIDEM)University Hospitals Cleveland Medical Center (UHCMC)ClevelandOhio
- MedicineCase Western Reserve University (CWRU)ClevelandOhio
- PharmacologyCase Western Reserve University (CWRU)ClevelandOhio
| | - Douglas S. Kerr
- PediatricsCase Western Reserve University (CWRU)ClevelandOhio
- Center for Inherited Disorders of Energy Metabolism (CIDEM)University Hospitals Cleveland Medical Center (UHCMC)ClevelandOhio
| | - Gerard T. Berry
- Division of Genetics and Genomics, The Manton Center for Orphan Disease ResearchBoston Children's Hospital, Harvard Medical SchoolBostonMassachusetts
| |
Collapse
|
10
|
Nimmo GAM, Venkatesh S, Pandey AK, Marshall CR, Hazrati LN, Blaser S, Ahmed S, Cameron J, Singh K, Ray PN, Suzuki CK, Yoon G. Bi-allelic mutations of LONP1 encoding the mitochondrial LonP1 protease cause pyruvate dehydrogenase deficiency and profound neurodegeneration with progressive cerebellar atrophy. Hum Mol Genet 2019; 28:290-306. [PMID: 30304514 DOI: 10.1093/hmg/ddy351] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 09/28/2018] [Indexed: 12/30/2022] Open
Abstract
LonP1 is crucial for maintaining mitochondrial proteostasis and mitigating cell stress. We identified a novel homozygous missense LONP1 variant, c.2282 C > T, (p.Pro761Leu), by whole-exome and Sanger sequencing in two siblings born to healthy consanguineous parents. Both siblings presented with stepwise regression during infancy, profound hypotonia and muscle weakness, severe intellectual disability and progressive cerebellar atrophy on brain imaging. Muscle biopsy revealed the absence of ragged-red fibers, however, scattered cytochrome c oxidase-negative staining and electron dense mitochondrial inclusions were observed. Primary cultured fibroblasts from the siblings showed normal levels of mtDNA and mitochondrial transcripts, and normal activities of oxidative phosphorylation complexes I through V. Interestingly, fibroblasts of both siblings showed glucose-repressed oxygen consumption compared to their mother, whereas galactose and palmitic acid utilization were similar. Notably, the siblings' fibroblasts had reduced pyruvate dehydrogenase (PDH) activity and elevated intracellular lactate:pyruvate ratios, whereas plasma ratios were normal. We demonstrated that in the siblings' fibroblasts, PDH dysfunction was caused by increased levels of the phosphorylated E1α subunit of PDH, which inhibits enzyme activity. Blocking E1α phosphorylation activated PDH and reduced intracellular lactate concentrations. In addition, overexpressing wild-type LonP1 in the siblings' fibroblasts down-regulated phosphoE1α. Furthermore, in vitro studies demonstrated that purified LonP1-P761L failed to degrade phosphorylated E1α, in contrast to wild-type LonP1. We propose a novel mechanism whereby homozygous expression of the LonP1-P761L variant leads to PDH deficiency and energy metabolism dysfunction, which promotes severe neurologic impairment and neurodegeneration.
Collapse
Affiliation(s)
- Graeme A M Nimmo
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Sundararajan Venkatesh
- Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Ashutosh K Pandey
- Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Christian R Marshall
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.,The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Lili-Naz Hazrati
- Division of Neuropathology, The Hospital for Sick Children, The University of Toronto, Toronto, Ontario, Canada
| | - Susan Blaser
- Division of Paediatric Neuroradiology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Sohnee Ahmed
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Jessie Cameron
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Kamalendra Singh
- Molecular Microbiology and Immunology, Christopher Bond Life Sciences Center, University of Missouri School of Medicine, Columbia, Missouri, USA.,Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, Stockholm, SE Sweden
| | - Peter N Ray
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.,The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Molecular Genetics, The University of Toronto, Toronto, Ontario, Canada
| | - Carolyn K Suzuki
- Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Grace Yoon
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.,Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, The University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
11
|
Oyarzabal A, Marin-Valencia I. Synaptic energy metabolism and neuronal excitability, in sickness and health. J Inherit Metab Dis 2019; 42:220-236. [PMID: 30734319 DOI: 10.1002/jimd.12071] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 01/06/2019] [Accepted: 01/30/2019] [Indexed: 12/11/2022]
Abstract
Most of the energy produced in the brain is dedicated to supporting synaptic transmission. Glucose is the main fuel, providing energy and carbon skeletons to the cells that execute and support synaptic function: neurons and astrocytes, respectively. It is unclear, however, how glucose is provided to and used by these cells under different levels of synaptic activity. It is even more unclear how diseases that impair glucose uptake and oxidation in the brain alter metabolism in neurons and astrocytes, disrupt synaptic activity, and cause neurological dysfunction, of which seizures are one of the most common clinical manifestations. Poor mechanistic understanding of diseases involving synaptic energy metabolism has prevented the expansion of therapeutic options, which, in most cases, are limited to symptomatic treatments. To shed light on the intersections between metabolism, synaptic transmission, and neuronal excitability, we briefly review current knowledge of compartmentalized metabolism in neurons and astrocytes, the biochemical pathways that fuel synaptic transmission at resting and active states, and the mechanisms by which disorders of brain glucose metabolism disrupt neuronal excitability and synaptic function and cause neurological disease in the form of epilepsy.
Collapse
Affiliation(s)
- Alfonso Oyarzabal
- Synaptic Metabolism Laboratory, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | - Isaac Marin-Valencia
- Laboratory of Developmental Neurobiology, The Rockefeller University, New York, New York
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Guo X, Niemi NM, Coon JJ, Pagliarini DJ. Integrative proteomics and biochemical analyses define Ptc6p as the Saccharomyces cerevisiae pyruvate dehydrogenase phosphatase. J Biol Chem 2017; 292:11751-11759. [PMID: 28539364 DOI: 10.1074/jbc.m117.787341] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/12/2017] [Indexed: 01/27/2023] Open
Abstract
The pyruvate dehydrogenase complex (PDC) is the primary metabolic checkpoint connecting glycolysis and mitochondrial oxidative phosphorylation and is important for maintaining cellular and organismal glucose homeostasis. Phosphorylation of the PDC E1 subunit was identified as a key inhibitory modification in bovine tissue ∼50 years ago, and this regulatory process is now known to be conserved throughout evolution. Although Saccharomyces cerevisiae is a pervasive model organism for investigating cellular metabolism and its regulation by signaling processes, the phosphatase(s) responsible for activating the PDC in S. cerevisiae has not been conclusively defined. Here, using comparative mitochondrial phosphoproteomics, analyses of protein-protein interactions by affinity enrichment-mass spectrometry, and in vitro biochemistry, we define Ptc6p as the primary PDC phosphatase in S. cerevisiae Our analyses further suggest additional substrates for related S. cerevisiae phosphatases and describe the overall phosphoproteomic changes that accompany mitochondrial respiratory dysfunction. In summary, our quantitative proteomics and biochemical analyses have identified Ptc6p as the primary-and likely sole-S. cerevisiae PDC phosphatase, closing a key knowledge gap about the regulation of yeast mitochondrial metabolism. Our findings highlight the power of integrative omics and biochemical analyses for annotating the functions of poorly characterized signaling proteins.
Collapse
Affiliation(s)
- Xiao Guo
- Morgridge Institute for Research, Madison, Wisconsin 53715; Departments of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Natalie M Niemi
- Morgridge Institute for Research, Madison, Wisconsin 53715; Departments of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Joshua J Coon
- Morgridge Institute for Research, Madison, Wisconsin 53715; Departments of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706; Genome Center of Wisconsin, Madison, Wisconsin 53706; Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - David J Pagliarini
- Morgridge Institute for Research, Madison, Wisconsin 53715; Departments of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
| |
Collapse
|
14
|
E4F1 controls a transcriptional program essential for pyruvate dehydrogenase activity. Proc Natl Acad Sci U S A 2016; 113:10998-1003. [PMID: 27621446 DOI: 10.1073/pnas.1602754113] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The mitochondrial pyruvate dehydrogenase (PDH) complex (PDC) acts as a central metabolic node that mediates pyruvate oxidation and fuels the tricarboxylic acid cycle to meet energy demand. Here, we reveal another level of regulation of the pyruvate oxidation pathway in mammals implicating the E4 transcription factor 1 (E4F1). E4F1 controls a set of four genes [dihydrolipoamide acetlytransferase (Dlat), dihydrolipoyl dehydrogenase (Dld), mitochondrial pyruvate carrier 1 (Mpc1), and solute carrier family 25 member 19 (Slc25a19)] involved in pyruvate oxidation and reported to be individually mutated in human metabolic syndromes. E4F1 dysfunction results in 80% decrease of PDH activity and alterations of pyruvate metabolism. Genetic inactivation of murine E4f1 in striated muscles results in viable animals that show low muscle PDH activity, severe endurance defects, and chronic lactic acidemia, recapitulating some clinical symptoms described in PDC-deficient patients. These phenotypes were attenuated by pharmacological stimulation of PDH or by a ketogenic diet, two treatments used for PDH deficiencies. Taken together, these data identify E4F1 as a master regulator of the PDC.
Collapse
|
15
|
Requirement for the Mitochondrial Pyruvate Carrier in Mammalian Development Revealed by a Hypomorphic Allelic Series. Mol Cell Biol 2016; 36:2089-104. [PMID: 27215380 DOI: 10.1128/mcb.00166-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/13/2016] [Indexed: 11/20/2022] Open
Abstract
Glucose and oxygen are two of the most important molecules transferred from mother to fetus during eutherian pregnancy, and the metabolic fates of these nutrients converge at the transport and metabolism of pyruvate in mitochondria. Pyruvate enters the mitochondrial matrix through the mitochondrial pyruvate carrier (MPC), a complex in the inner mitochondrial membrane that consists of two essential components, MPC1 and MPC2. Here, we define the requirement for mitochondrial pyruvate metabolism during development with a progressive allelic series of Mpc1 deficiency in mouse. Mpc1 deletion was homozygous lethal in midgestation, but Mpc1 hypomorphs and tissue-specific deletion of Mpc1 presented as early perinatal lethality. The allelic series demonstrated that graded suppression of MPC resulted in dose-dependent metabolic and transcriptional changes. Steady-state metabolomics analysis of brain and liver from Mpc1 hypomorphic embryos identified compensatory changes in amino acid and lipid metabolism. Flux assays in Mpc1-deficient embryonic fibroblasts also reflected these changes, including a dramatic increase in mitochondrial alanine utilization. The mitochondrial alanine transaminase GPT2 was found to be necessary and sufficient for increased alanine flux upon MPC inhibition. These data show that impaired mitochondrial pyruvate transport results in biosynthetic deficiencies that can be mitigated in part by alternative anaplerotic substrates in utero.
Collapse
|
16
|
Legati A, Reyes A, Nasca A, Invernizzi F, Lamantea E, Tiranti V, Garavaglia B, Lamperti C, Ardissone A, Moroni I, Robinson A, Ghezzi D, Zeviani M. New genes and pathomechanisms in mitochondrial disorders unraveled by NGS technologies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1326-1335. [PMID: 26968897 DOI: 10.1016/j.bbabio.2016.02.022] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 02/17/2016] [Accepted: 02/27/2016] [Indexed: 12/13/2022]
Abstract
Next Generation Sequencing (NGS) technologies are revolutionizing the diagnostic screening for rare disease entities, including primary mitochondrial disorders, particularly those caused by nuclear gene defects. NGS approaches are able to identify the causative gene defects in small families and even single individuals, unsuitable for investigation by traditional linkage analysis. These technologies are contributing to fill the gap between mitochondrial disease cases defined on the basis of clinical, neuroimaging and biochemical readouts, which still outnumber by approximately 50% the cases for which a molecular-genetic diagnosis is attained. We have been using a combined, two-step strategy, based on targeted genes panel as a first NGS screening, followed by whole exome sequencing (WES) in still unsolved cases, to analyze a large cohort of subjects, that failed to show mutations in mtDNA and in ad hoc sets of specific nuclear genes, sequenced by the Sanger's method. Not only this approach has allowed us to reach molecular diagnosis in a significant fraction (20%) of these difficult cases, but it has also revealed unexpected and conceptually new findings. These include the possibility of marked variable penetrance of recessive mutations, the identification of large-scale DNA rearrangements, which explain spuriously heterozygous cases, and the association of mutations in known genes with unusual, previously unreported clinical phenotypes. Importantly, WES on selected cases has unraveled the presence of pathogenic mutations in genes encoding non-mitochondrial proteins (e.g. the transcription factor E4F1), an observation that further expands the intricate genetics of mitochondrial disease and suggests a new area of investigation in mitochondrial medicine. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
Collapse
Affiliation(s)
- Andrea Legati
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Aurelio Reyes
- Mitochondrial Biology Unit, Medical Research Council, Cambridge CB2 0XY, UK
| | - Alessia Nasca
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Federica Invernizzi
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Eleonora Lamantea
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Valeria Tiranti
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Barbara Garavaglia
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Costanza Lamperti
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy
| | - Anna Ardissone
- Unit of Child Neurology, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20133 Milan, Italy
| | - Isabella Moroni
- Unit of Child Neurology, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20133 Milan, Italy
| | - Alan Robinson
- Mitochondrial Biology Unit, Medical Research Council, Cambridge CB2 0XY, UK
| | - Daniele Ghezzi
- Unit of Molecular Neurogenetics, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', 20126 Milan, Italy.
| | - Massimo Zeviani
- Mitochondrial Biology Unit, Medical Research Council, Cambridge CB2 0XY, UK.
| |
Collapse
|
17
|
Cameron JM, MacKay N, Feigenbaum A, Tarnopolsky M, Blaser S, Robinson BH, Schulze A. Exome sequencing identifies complex I NDUFV2 mutations as a novel cause of Leigh syndrome. Eur J Paediatr Neurol 2015; 19:525-32. [PMID: 26008862 DOI: 10.1016/j.ejpn.2015.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 02/12/2015] [Accepted: 05/05/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND Two siblings with hypertrophic cardiomyopathy and brain atrophy were diagnosed with Complex I deficiency based on low enzyme activity in muscle and high lactate/pyruvate ratio in fibroblasts. METHODS Whole exome sequencing results of fibroblast gDNA from one sibling was narrowed down to 190 SNPs or In/Dels in 185 candidate genes by selecting non-synonymous coding sequence base pair changes that were not present in the SNP database. RESULTS Two compound heterozygous mutations were identified in both siblings in NDUFV2, encoding the 24 kDa subunit of Complex I. The intronic mutation (c.IVS2 + 1delGTAA) is disease causing and has been reported before. The other mutation is novel (c.669_670insG, p.Ser224Valfs*3) and predicted to cause a pathogenic frameshift in the protein. Subsequent investigation of 10 probands with complex I deficiency from different families revealed homozygosity for the intronic c.IVS2 + 1delGTAA mutation in a second, consanguineous family. In this family three of five siblings were affected. Interestingly, they presented with Leigh syndrome but no cardiac involvement. The same genotype had been reported previously in a two families but presenting with hypertrophic cardiomyopathy, trunk hypotonia and encephalopathy. CONCLUSION We have identified NDUFV2 mutations in two families with Complex I deficiency, including a novel mutation. The diagnosis of Leigh syndrome expands the clinical phenotypes associated with the c.IVS2 + 1delGTAA mutation in this gene.
Collapse
Affiliation(s)
- Jessie M Cameron
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
| | - Nevena MacKay
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
| | - Annette Feigenbaum
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, ON M5G 1X8, Canada.
| | - Mark Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada.
| | - Susan Blaser
- Department of Radiology, The Hospital for Sick Children and University of Toronto, ON M5G 1X8, Canada.
| | - Brian H Robinson
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Andreas Schulze
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, ON M5G 1X8, Canada.
| |
Collapse
|
18
|
Bhandary S, Aguan K. Pyruvate dehydrogenase complex deficiency and its relationship with epilepsy frequency--An overview. Epilepsy Res 2015; 116:40-52. [PMID: 26354166 DOI: 10.1016/j.eplepsyres.2015.07.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 06/29/2015] [Accepted: 07/05/2015] [Indexed: 12/18/2022]
Abstract
The pyruvate dehydrogenase complex (PDHc) is a member of a family of multienzyme complexes that provides the link between glycolysis and the tricarboxylic acid (TCA) cycle by catalyzing the physiologically irreversible decarboxylation of various 2-oxoacid substrates to their corresponding acyl-CoA derivatives, NADH and CO2. PDHc deficiency is a metabolic disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration that vary with age and gender. In this review, we aim to discuss the relationship between occurrence of epilepsy and PDHc deficiency associated with the pyruvate dehydrogenase complex (E1α subunit (PDHA1) and E1β subunit (PDHB)) and PDH phosphatase (PDP) deficiency. PDHc plays a crucial role in the aerobic carbohydrate metabolism and regulates the use of carbohydrate as the source of oxidative energy. In severe PDHc deficiency, the energy deficit impairs brain development in utero resulting in physiological and structural changes in the brain that contributes to the subsequent onset of epileptogenesis. Epileptogenesis in PDHc deficiency is linked to energy failure and abnormal neurotransmitter metabolism that progressively alters neuronal excitability. This metabolic blockage might be restricted via inclusion of ketogenic diet that is broken up by β-oxidation and directly converting it to acetyl-CoA, and thereby improving the patient's health condition. Genetic counseling is essential as PDHA1 deficiency is X-linked. The demonstration of the X-chromosome localization of PDHA1 resolved a number of questions concerning the variable phenotype displayed by patients with E1 deficiency. Most patients show a broad range of neurological abnormalities, with the severity showing some dependence on the nature of the mutation in the Elα gene, while PDHB and PDH phosphatase (PDP) deficiencies are of autosomal recessive inheritance. However, in females, the disorder is further complicated by the pattern of X-chromosome inactivation, i.e., unfavorable lyonization. Furthermore research should focus on epileptogenic animal models; this might pave a new way toward identification of the pathophysiology of this challenging disorder.
Collapse
Affiliation(s)
- Suman Bhandary
- Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong 793 022, India; Division of Molecular Medicine, Bose Institute, Kolkata 700 054, India
| | - Kripamoy Aguan
- Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong 793 022, India.
| |
Collapse
|
19
|
Sperl W, Fleuren L, Freisinger P, Haack TB, Ribes A, Feichtinger RG, Rodenburg RJ, Zimmermann FA, Koch J, Rivera I, Prokisch H, Smeitink JA, Mayr JA. The spectrum of pyruvate oxidation defects in the diagnosis of mitochondrial disorders. J Inherit Metab Dis 2015; 38:391-403. [PMID: 25526709 DOI: 10.1007/s10545-014-9787-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 10/20/2014] [Accepted: 10/23/2014] [Indexed: 10/24/2022]
Abstract
Pyruvate oxidation defects (PODs) are among the most frequent causes of deficiencies in the mitochondrial energy metabolism and represent a substantial subset of classical mitochondrial diseases. PODs are not only caused by deficiency of subunits of the pyruvate dehydrogenase complex (PDHC) but also by various disorders recently described in the whole pyruvate oxidation route including cofactors, regulation of PDHC and the mitochondrial pyruvate carrier. Our own patients from 2000 to July 2014 and patients identified by a systematic survey of the literature from 1970 to July 2014 with a pyruvate oxidation disorder and a genetically proven defect were included in the study (n=628). Of these defects 74.2% (n=466) belong to PDHC subunits, 24.5% (n=154) to cofactors, 0.5% (n=3) to PDHC regulation and 0.8% (n=5) to mitochondrial pyruvate import. PODs are underestimated in the field of mitochondrial diseases because not all diagnostic centres include biochemical investigations of PDHC in their routine analysis. Cofactor and transport defects can be missed, if pyruvate oxidation is not measured in intact mitochondria routinely. Furthermore deficiency of the X-chromosomal PDHA1 can be biochemically missed depending on the X-inactivation pattern. This is reflected by an increasing number of patients diagnosed recently by genetic high throughput screening approaches. PDHC deficiency including regulation and import affect mainly the glucose dependent central and peripheral nervous system and skeletal muscle. PODs with combined enzyme defects affect also other organs like heart, lung and liver. The spectrum of clinical presentation of PODs is still expanding. PODs are a therapeutically interesting group of mitochondrial diseases since some can be bypassed by ketogenic diet or treated by cofactor supplementation. PDHC kinase inhibition, chaperone therapy and PGC1α stimulation is still a matter of further investigations.
Collapse
Affiliation(s)
- Wolfgang Sperl
- Department of Paediatrics, Paracelsus Medical University, SALK Salzburg, Salzburg, 5020, Austria,
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Ferriero R, Boutron A, Brivet M, Kerr D, Morava E, Rodenburg RJ, Bonafé L, Baumgartner MR, Anikster Y, Braverman NE, Brunetti-Pierri N. Phenylbutyrate increases pyruvate dehydrogenase complex activity in cells harboring a variety of defects. Ann Clin Transl Neurol 2014; 1:462-70. [PMID: 25356417 PMCID: PMC4184775 DOI: 10.1002/acn3.73] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/20/2014] [Accepted: 05/20/2014] [Indexed: 11/30/2022] Open
Abstract
Objective Deficiency of pyruvate dehydrogenase complex (PDHC) is the most common genetic disorder leading to lactic acidosis. PDHC deficiency is genetically heterogenous and most patients have defects in the X-linked E1-α gene but defects in the other components of the complex encoded by PDHB, PDHX, DLAT, DLD genes or in the regulatory enzyme encoded by PDP1 have also been found. Phenylbutyrate enhances PDHC enzymatic activity in vitro and in vivo by increasing the proportion of unphosphorylated enzyme through inhibition of pyruvate dehydrogenase kinases and thus, has potential for therapy of patients with PDHC deficiency. In the present study, we investigated response to phenylbutyrate of multiple cell lines harboring all known gene defects resulting in PDHC deficiency. Methods Fibroblasts of patients with PDHC deficiency were studied for their enzyme activity at baseline and following phenylbutyrate incubation. Drug responses were correlated with genotypes and protein levels by Western blotting. Results Large deletions affecting PDHA1 that result in lack of detectable protein were unresponsive to phenylbutyrate, whereas increased PDHC activity was detected in most fibroblasts harboring PDHA1 missense mutations. Mutations affecting the R349-α residue were directed to proteasome degradation and were consistently unresponsive to short-time drug incubation but longer incubation resulted in increased levels of enzyme activity and protein that may be due to an additional effect of phenylbutyrate as a molecular chaperone. Interpretation PDHC enzyme activity was enhanced by phenylbutyrate in cells harboring missense mutations in PDHB, PDHX, DLAT, DLD, and PDP1 genes. In the prospect of a clinical trial, the results of this study may allow prediction of in vivo response in patients with PDHC deficiency harboring a wide spectrum of molecular defects.
Collapse
Affiliation(s)
- Rosa Ferriero
- Telethon Institute of Genetics and MedicineNaples, Italy
| | - Audrey Boutron
- Laboratoire de Biochimie, AP-HP Hôpital de BicêtreLe Kremlin Bicêtre, France
| | - Michele Brivet
- Laboratoire de Biochimie, AP-HP Hôpital de BicêtreLe Kremlin Bicêtre, France
| | - Douglas Kerr
- Center for Inherited Disorders of Energy Metabolism, Case Western Reserve UniversityCleveland, Ohio, USA
| | - Eva Morava
- Hayward Genetics Center, Tulane University Medical SchoolNew Orleans, Louisiana, USA
| | - Richard J Rodenburg
- Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical CenterNijmegen, The Netherlands
| | - Luisa Bonafé
- Center for Molecular Diseases, Lausanne University HospitalLausanne, Switzerland
| | - Matthias R Baumgartner
- Division for Metabolic Diseases and Children's Research Center, University Children's HospitalZürich, Switzerland
| | - Yair Anikster
- Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer and Sackler School of Medicine, Tel Aviv UniversityTel Aviv, Israel
| | - Nancy E Braverman
- Department of Human Genetics, McGill UniversityMontreal, Quebec, Canada
- Department of Pediatrics, Montreal Children's Hospital MontrealMontreal, Quebec, Canada
| | - Nicola Brunetti-Pierri
- Telethon Institute of Genetics and MedicineNaples, Italy
- Department of Translational Medicine, Federico II University of NaplesNaples, Italy
- Correspondence Nicola Brunetti-Pierri, Telethon Institute of Genetics and Medicine, Via P. Castellino, 111, 80131 Napoli, Italy. Tel: +39 081 6132361; Fax: +39 081 5609877; E-mail:
| |
Collapse
|
21
|
Gray LR, Tompkins SC, Taylor EB. Regulation of pyruvate metabolism and human disease. Cell Mol Life Sci 2013; 71:2577-604. [PMID: 24363178 PMCID: PMC4059968 DOI: 10.1007/s00018-013-1539-2] [Citation(s) in RCA: 514] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 11/24/2013] [Accepted: 12/02/2013] [Indexed: 12/31/2022]
Abstract
Pyruvate is a keystone molecule critical for numerous aspects of eukaryotic and human metabolism. Pyruvate is the end-product of glycolysis, is derived from additional sources in the cellular cytoplasm, and is ultimately destined for transport into mitochondria as a master fuel input undergirding citric acid cycle carbon flux. In mitochondria, pyruvate drives ATP production by oxidative phosphorylation and multiple biosynthetic pathways intersecting the citric acid cycle. Mitochondrial pyruvate metabolism is regulated by many enzymes, including the recently discovered mitochondria pyruvate carrier, pyruvate dehydrogenase, and pyruvate carboxylase, to modulate overall pyruvate carbon flux. Mutations in any of the genes encoding for proteins regulating pyruvate metabolism may lead to disease. Numerous cases have been described. Aberrant pyruvate metabolism plays an especially prominent role in cancer, heart failure, and neurodegeneration. Because most major diseases involve aberrant metabolism, understanding and exploiting pyruvate carbon flux may yield novel treatments that enhance human health.
Collapse
Affiliation(s)
- Lawrence R Gray
- Department of Biochemistry, Fraternal Order of the Eagles Diabetes Research Center, and François M. Abboud Cardiovascular Research Center, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 51 Newton Rd, 4-403 BSB, Iowa City, IA, 52242, USA
| | | | | |
Collapse
|
22
|
Scheibye-Knudsen M, Croteau DL, Bohr VA. Mitochondrial deficiency in Cockayne syndrome. Mech Ageing Dev 2013; 134:275-83. [PMID: 23435289 PMCID: PMC3663877 DOI: 10.1016/j.mad.2013.02.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 01/24/2013] [Accepted: 02/08/2013] [Indexed: 01/05/2023]
Abstract
Cockayne syndrome is a rare inherited disorder characterized by accelerated aging, cachectic dwarfism and many other features. Recent work has implicated mitochondrial dysfunction in the pathogenesis of this disease. This is particularly interesting since mitochondrial deficiencies are believed to be important in the aging process. In this review, we discuss recent findings of mitochondrial pathology in Cockayne syndrome and suggest possible mechanisms for the mitochondrial dysfunction.
Collapse
Affiliation(s)
| | - Deborah L. Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, USA
| | - Vilhelm A. Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, USA
| |
Collapse
|
23
|
Vernau KM, Runstadler JA, Brown EA, Cameron JM, Huson HJ, Higgins RJ, Ackerley C, Sturges BK, Dickinson PJ, Puschner B, Giulivi C, Shelton GD, Robinson BH, DiMauro S, Bollen AW, Bannasch DL. Genome-wide association analysis identifies a mutation in the thiamine transporter 2 (SLC19A3) gene associated with Alaskan Husky encephalopathy. PLoS One 2013; 8:e57195. [PMID: 23469184 PMCID: PMC3587633 DOI: 10.1371/journal.pone.0057195] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 01/18/2013] [Indexed: 11/28/2022] Open
Abstract
Alaskan Husky Encephalopathy (AHE) has been previously proposed as a mitochondrial encephalopathy based on neuropathological similarities with human Leigh Syndrome (LS). We studied 11 Alaskan Husky dogs with AHE, but found no abnormalities in respiratory chain enzyme activities in muscle and liver, or mutations in mitochondrial or nuclear genes that cause LS in people. A genome wide association study was performed using eight of the affected dogs and 20 related but unaffected control AHs using the Illumina canine HD array. SLC19A3 was identified as a positional candidate gene. This gene controls the uptake of thiamine in the CNS via expression of the thiamine transporter protein THTR2. Dogs have two copies of this gene located within the candidate interval (SLC19A3.2 – 43.36–43.38 Mb and SLC19A3.1 – 43.411–43.419 Mb) on chromosome 25. Expression analysis in a normal dog revealed that one of the paralogs, SLC19A3.1, was expressed in the brain and spinal cord while the other was not. Subsequent exon sequencing of SLC19A3.1 revealed a 4bp insertion and SNP in the second exon that is predicted to result in a functional protein truncation of 279 amino acids (c.624 insTTGC, c.625 C>A). All dogs with AHE were homozygous for this mutation, 15/41 healthy AH control dogs were heterozygous carriers while 26/41 normal healthy AH dogs were wild type. Furthermore, this mutation was not detected in another 187 dogs of different breeds. These results suggest that this mutation in SLC19A3.1, encoding a thiamine transporter protein, plays a critical role in the pathogenesis of AHE.
Collapse
Affiliation(s)
- Karen M Vernau
- University of California Davis, Davis, California, United States of America.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Siriwardena K, Mackay N, Levandovskiy V, Blaser S, Raiman J, Kantor PF, Ackerley C, Robinson BH, Schulze A, Cameron JM. Mitochondrial citrate synthase crystals: novel finding in Sengers syndrome caused by acylglycerol kinase (AGK) mutations. Mol Genet Metab 2013; 108:40-50. [PMID: 23266196 DOI: 10.1016/j.ymgme.2012.11.282] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 11/24/2012] [Indexed: 11/16/2022]
Abstract
We report on two families with Sengers syndrome and mutations in the acylglycerol kinase gene (AGK). In the first family, two brothers presented with vascular strokes, lactic acidosis, cardiomyopathy and cataracts, abnormal muscle cell histopathology and mitochondrial function. One proband had very abnormal mitochondria with citrate synthase crystals visible in electron micrographs, associated with markedly high citrate synthase activity. Exome sequencing was used to identify mutations in the AGK gene in the index patient. Targeted sequencing confirmed the same homozygous mutation (c.3G>A, p.M1I) in the brother. The second family had four affected members, of which we examined two. They also presented with similar clinical symptoms, but no strokes. Postmortem heart and skeletal muscle tissues showed low complex I, III and IV activities in the heart, but normal in the muscle. Skin fibroblasts showed elevated lactate/pyruvate ratios and low complex I+III activity. Targeted sequencing led to identification of a homozygous c.979A>T, p.K327* mutation. AGK is located in the mitochondria and phosphorylates monoacylglycerol and diacylglycerol to lysophosphatidic acid and phosphatidic acid. Disruption of these signaling molecules affects the mitochondria's response to superoxide radicals, resulting in oxidative damage to mitochondrial DNA, lipids and proteins, and stimulation of cellular detoxification pathways. High levels of manganese superoxide dismutase protein were detected in all four affected individuals, consistent with increased free radical damage. Phosphatidic acid is also involved in the synthesis of phospholipids and its loss will result in changes to the lipid composition of the inner mitochondrial membrane. These effects manifest as cataract formation in the eye, respiratory chain dysfunction and cardiac hypertrophy in heart tissue. These two pedigrees confirm that mutation of AGK is responsible for the severe neonatal presentation of Sengers syndrome. The identification of citrate synthase precipitates by electron microscopy and the presence of vascular strokes in two siblings may expand the cellular and clinical phenotype of this disease.
Collapse
Affiliation(s)
- Komudi Siriwardena
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, ON, Canada M5G 1X8
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Pyruvate dehydrogenase and pyruvate carboxylase deficiency are the most common disorders in pyruvate metabolism. Diagnosis is made by enzymatic and DNA analysis after basic biochemical tests in plasma, urine, and CSF. Pyruvate dehydrogenase has three main subunits, an additional E3-binding protein and two complex regulatory enzymes. Most frequent are deficiencies in PDH-E1α. There is a spectrum of clinical presentations in E1α deficiency, ranging in boys from severe neonatal lactic acidosis, Leigh encephalopathy, to later onset of neurological disease such as intermittent ataxia or dystonia. Females tend to have a more uniform presentation resembling nonprogressive cerebral palsy. Neuroradiological abnormalities such as corpus callosum agenesis are seen more frequently in girls, basal ganglia and midbrain disturbances in boys. Deficiencies in the other subunits have also been described, but in a smaller number of patients. Pyruvate carboxylase deficiency has three clinical phenotypes. The infantile type is characterized mainly by severe developmental delay, failure to thrive, and seizures. The second type is characterized by neonatal onset of severe lactic acidosis with rigidity and hypokinesia. A third form is rarer with intermittent episodes of lactic acidosis and ketoacidosis. Neuroradiological findings such as cystic periventricular leukomalacia have been described.
Collapse
|
26
|
Oyarzabal A, Martínez-Pardo M, Merinero B, Navarrete R, Desviat LR, Ugarte M, Rodríguez-Pombo P. A novel regulatory defect in the branched-chain α-keto acid dehydrogenase complex due to a mutation in the PPM1K gene causes a mild variant phenotype of maple syrup urine disease. Hum Mutat 2012; 34:355-62. [PMID: 23086801 DOI: 10.1002/humu.22242] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 10/04/2012] [Indexed: 11/11/2022]
Abstract
This article describes a hitherto unreported involvement of the phosphatase PP2Cm, a recently described member of the branched-chain α-keto acid dehydrogenase (BCKDH) complex, in maple syrup urine disease (MSUD). The disease-causing mutation was identified in a patient with a mild variant phenotype, involving a gene not previously associated with MSUD. SNP array-based genotyping showed a copy-neutral homozygous pattern for chromosome 4 compatible with uniparental isodisomy. Mutation analysis of the candidate gene, PPM1K, revealed a homozygous c.417_418delTA change predicted to result in a truncated, unstable protein. No PP2Cm mutant protein was detected in immunocytochemical or Western blot expression analyses. The transient expression of wild-type PPM1K in PP2Cm-deficient fibroblasts recovered 35% of normal BCKDH activity. As PP2Cm has been described essential for cell survival, apoptosis and metabolism, the impact of its deficiency on specific metabolic stress variables was evaluated in PP2Cm-deficient fibroblasts. Increases were seen in ROS levels along with the activation of specific stress-signaling MAP kinases. Similar to that described for the pyruvate dehydrogenase complex, a defect in the regulation of BCKDH caused the aberrant metabolism of its substrate, contributing to the patient's MSUD phenotype--and perhaps others.
Collapse
Affiliation(s)
- Alfonso Oyarzabal
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa CSIC-UAM, Departamento de Biología Molecular, Universidad Autónoma de Madrid, CIBERER U746, IDIPAZ, Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
27
|
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: 70] [Impact Index Per Article: 5.8] [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.
Collapse
|
28
|
Abstract
Pyruvate dehydrogenase complex (PDC) and pyruvate carboxylase (PC) are mitochondrial enzymes that provide the initial steps of the two main alternatives for pyruvate metabolism: oxidative decarboxylation vs. anaplerotic carboxylation, gluconeogenesis, and glycerogenesis. Assays of the enzymatic activity of these two enzymes in cells and tissues are described in this chapter, based on evolution or fixation of (14)CO(2). These assays are both suitable for use in crude homogenates of cultured skin fibroblasts, lymphocytes, and frozen muscle (PDC) or liver (PC). Activities of these two enzymes are related to spectrophotometric assays of two other mitochondrial enzymes, dihydrolipoamide dehydrogenase (E3) and citrate synthase (CS), providing initial indices of sample integrity and mitochondrial content. These parameters have proven useful for initial detection of inherited human disorders due to deficiencies of these enzymes, and in combination with available genetic analyses can lead to confirmation of specific diagnoses.
Collapse
|
29
|
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.
Collapse
Affiliation(s)
- A Imbard
- Biochimie-Hôpital de Bicêtre, Hôpitaux Universitaires Paris-Sud, AP-HP, Paris, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Prasad C, Rupar T, Prasad AN. Pyruvate dehydrogenase deficiency and epilepsy. Brain Dev 2011; 33:856-65. [PMID: 21908116 DOI: 10.1016/j.braindev.2011.08.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 07/27/2011] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
Abstract
The pyruvate dehydrogenase complex (PDHc) is a mitochondrial matrix multienzyme complex that provides the link between glycolysis and the tricarboxylic acid (TCA) cycle by catalyzing the conversion of pyruvate into acetyl-CoA. PDHc deficiency is one of the commoner metabolic disorders of lactic acidosis presenting with neurological phenotypes that vary with age and gender. In this mini-review, we postulate mechanisms of epilepsy in the setting of PDHc deficiency using two illustrative cases (one with pyruvate dehydrogenase complex E1-alpha polypeptide (PDHA1) deficiency and the second one with pyruvate dehydrogenase complex E1-beta subunit (PDHB) deficiency (a rare subtype of PDHc deficiency)) and a selected review of published case series. PDHc plays a critical role in the pathway of carbohydrate metabolism and energy production. In severe deficiency states the resulting energy deficit impacts on brain development in utero resulting in structural brain anomalies and epilepsy. Milder deficiency states present with variable manifestations that include cognitive delay, ataxia, and seizures. Epileptogenesis in PDHc deficiency is linked to energy failure, development of structural brain anomalies and abnormal neurotransmitter metabolism. The use of the ketogenic diet bypasses the metabolic block, by providing a direct source of acetyl-CoA, leading to amelioration of some symptoms. Genetic counseling is essential as PDHA1 deficiency (commonest defect) is X-linked although females can be affected due to unfavorable lyonization, while PDHB and PDH phosphatase (PDP) deficiencies (much rarer defects) are of autosomal recessive inheritance. Research is in progress for looking into animal models to better understand pathogenesis and management of this challenging disorder.
Collapse
Affiliation(s)
- Chitra Prasad
- Department of Pediatrics, University of Western Ontario, London, Ontario, Canada.
| | | | | |
Collapse
|
31
|
Cameron J, Janer A, Levandovskiy V, MacKay N, Rouault T, Tong WH, Ogilvie I, Shoubridge E, Robinson B. Mutations in iron-sulfur cluster scaffold genes NFU1 and BOLA3 cause a fatal deficiency of multiple respiratory chain and 2-oxoacid dehydrogenase enzymes. Am J Hum Genet 2011; 89:486-95. [PMID: 21944046 DOI: 10.1016/j.ajhg.2011.08.011] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/25/2011] [Accepted: 08/29/2011] [Indexed: 10/17/2022] Open
Abstract
Severe combined deficiency of the 2-oxoacid dehydrogenases, associated with a defect in lipoate synthesis and accompanied by defects in complexes I, II, and III of the mitochondrial respiratory chain, is a rare autosomal recessive syndrome with no obvious causative gene defect. A candidate locus for this syndrome was mapped to chromosomal region 2p14 by microcell-mediated chromosome transfer in two unrelated families. Unexpectedly, analysis of genes in this area identified mutations in two different genes, both of which are involved in [Fe-S] cluster biogenesis. A homozygous missense mutation, c.545G>A, near the splice donor of exon 6 in NFU1 predicting a p.Arg182Gln substitution was found in one of the families. The mutation results in abnormal mRNA splicing of exon 6, and no mature protein could be detected in fibroblast mitochondria. A single base-pair duplication c.123dupA was identified in BOLA3 in the second family, causing a frame shift that produces a premature stop codon (p.Glu42Argfs(∗)13). Transduction of fibroblast lines with retroviral vectors expressing the mitochondrial, but not the cytosolic isoform of NFU1 and with isoform 1, but not isoform 2 of BOLA3 restored both respiratory chain function and oxoacid dehydrogenase complexes. NFU1 was previously proposed to be an alternative scaffold to ISCU for the biogenesis of [Fe-S] centers in mitochondria, and the function of BOLA3 was previously unknown. Our results demonstrate that both play essential roles in the production of [Fe-S] centers for the normal maturation of lipoate-containing 2-oxoacid dehydrogenases, and for the assembly of the respiratory chain complexes.
Collapse
|
32
|
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]
|
33
|
Kato J, Kato M. Crystallization and preliminary crystallographic studies of the catalytic subunits of human pyruvate dehydrogenase phosphatase isoforms 1 and 2. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:342-345. [PMID: 20208177 PMCID: PMC2833053 DOI: 10.1107/s1744309110003131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/25/2010] [Indexed: 05/28/2023]
Abstract
Pyruvate dehydrogenase phosphatase (PDP) is a mitochondrial serine phosphatase that activates phosphorylated pyruvate dehydrogenase complex by dephosphorylation. In humans, two PDP isoforms (1 and 2) have been identified. PDP1 is composed of a catalytic subunit (PDP1c) and a regulatory subunit (PDP1r), whereas PDP2 consists of only a catalytic subunit (PDP2c). Both PDP1c and PDP2c have been crystallized individually and complete X-ray diffraction data sets have been collected to 2.45 and 2.0 A resolution, respectively. The PDP1c crystals belonged to space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = b = 65.1, c = 216.1 A. The asymmetric unit is expected to contain one molecule, with a Matthews coefficient V(M) of 2.56 A(3) Da(-1). The PDP2c crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 53.6, b = 69.1, c = 109.7 A. The asymmetric unit is expected to contain one molecule, with a Matthews coefficient V(M) of 1.91 A(3) Da(-1).
Collapse
Affiliation(s)
- Junko Kato
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9030, USA
| | - Masato Kato
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9030, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9030, USA
| |
Collapse
|
34
|
Ostergaard E, Moller LB, Kalkanoglu-Sivri HS, Dursun A, Kibaek M, Thelle T, Christensen E, Duno M, Wibrand F. Four novel PDHA1 mutations in pyruvate dehydrogenase deficiency. J Inherit Metab Dis 2009; 32 Suppl 1:S235-9. [PMID: 19517265 DOI: 10.1007/s10545-009-1179-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 04/22/2009] [Accepted: 04/23/2009] [Indexed: 12/01/2022]
Abstract
The pyruvate dehydrogenase (PDH) complex is a mitochondrial multienzyme that catalyses the irreversible oxidative decarboxylation of pyruvate to acetyl-CoA. We report four novel PDHA1 mutations in patients with pyruvate dehydrogenase deficiency. Analysis of PDH activity showed decreased activity in fibroblasts from all four patients, around 16-52% of mean control, similar to what has been found in previous studies. Two of the mutations were missense mutations: c.616G>A (p.Glu206Lys) and c.457A>G (p.Met153Val), one was a 3 bp in-frame deletion: c.429_431delAGG (p.Gly143del), and one was a 65 bp duplication: c.900-6_958dup65. cDNA analysis of the 65 bp duplication showed a small amount of normal transcript in addition to the transcript corresponding to the duplication. The small amount of normal transcript likely explains the survival of the patient, who was a boy. The duplication and one of the missense mutations were associated with decreased amounts of E(1)α And E(1)β protein on western blot analysis, whereas the other two mutations were associated with normal amounts. This study adds four novel mutations to the around 90 reported mutations in PDHA1 (HGMD PDHA1 mutation database). The phenotypes of patients with PDH deficiency have been divided into three groups: a neonatal form with severe lactic acidosis, a form observed only in males and characterized by episodes of ataxia with relapses associated with hyperlactataemia, and an infantile form with hypotonia, lethargy, onset of seizures or dystonia, psychomotor retardation, in some cases Leigh-like lesions and mild to moderate hyperlactataemia. The four patients reported here all belong to the latter group, which is the largest.
Collapse
Affiliation(s)
- E Ostergaard
- Department of Clinical Genetics 4062, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, Copenhagen, 2100, Denmark.
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Abstract
INTRODUCTION The study of neurometabolic diseases is still in a prolonged preliminary stage. The catalogue of these diseases continues to grow; some known clinical syndromes have been subdivided into a number of variants once the genes that cause them have been identified, and at the same time new metabolic disorders have been discovered that aggravate or contribute to forms of epilepsy not previously classified as cerebral metabolic disorders. RESULTS This review presents the basic principles underlying the recognition and treatment of epilepsy caused by neurometabolic diseases. These disorders are divided (purely for the sake of convenience) into epilepsy presenting in newborn infants, children, and adolescents and adults, recognizing that there is a significant degree of overlap between these chronological stages. Current analytical methods and therapeutic approaches are summarized both from a general point of view and within the context of each clinical syndrome, acknowledging that each patient presents specific peculiarities and that, in general, antiepileptic drugs provide few benefits compared with more specific types of therapy (eg, special diets or vitamins) when indicated. We also include therapeutic recommendations and a general approach to fulminant epilepsies of neurometabolic origin, emphasizing the importance of identifying all of the proband's relatives who may be potential carriers of a genetic disorder during the diagnostic and genetic counselling process. Particular emphasis is placed on disorders for which there is curative treatment and on the importance of follow-up by expert professionals. CONCLUSION It is expected that in a few years' time it will be possible to know the metabolomic profile of these diseases (possibly by non-invasive methods), thus facilitating accurate diagnosis and making it possible to establish the response to treatment and to identify all individuals who are carriers or remain minimally symptomatic in terms of their risk of manifesting or transmitting epilepsy.
Collapse
Affiliation(s)
- Juan M Pascual
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | | |
Collapse
|
36
|
Cook SA, Collin GB, Bronson RT, Naggert JK, Liu DP, Akeson EC, Davisson MT. A mouse model for Meckel syndrome type 3. J Am Soc Nephrol 2009; 20:753-64. [PMID: 19211713 DOI: 10.1681/asn.2008040412] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Meckel-Gruber syndrome type 3 (MKS3; OMIM 607361) is a severe autosomal recessive disorder characterized by bilateral polycystic kidney disease. Other malformations associated with MKS3 include cystic changes in the liver, polydactyly, and brain abnormalities (occipital encephalocele, hydrocephalus, and Dandy Walker-type cerebellar anomalies). The disorder is hypothesized to be caused by defects in primary cilia. In humans, the underlying mutated gene, TMEM67, encodes transmembrane protein 67, also called meckelin (OMIM 609884), which is an integral protein of the renal epithelial cell and membrane of the primary cilium. Here, we describe a spontaneous deletion of the mouse ortholog, Tmem67, which results in polycystic kidney disease and death by 3 wk after birth. Hydrocephalus also occurs in some mutants. We verified the mutated gene by transgenic rescue and characterized the phenotype with microcomputed tomography, histology, scanning electron microscopy, and immunohistochemistry. This mutant provides a mouse model for MKS3 and adds to the growing set of mammalian models essential for studying the role of the primary cilium in kidney function.
Collapse
Affiliation(s)
- Susan A Cook
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA
| | | | | | | | | | | | | |
Collapse
|
37
|
Cameron JM, Maj M, Levandovskiy V, Barnett CP, Blaser S, Mackay N, Raiman J, Feigenbaum A, Schulze A, Robinson BH. Pyruvate dehydrogenase phosphatase 1 (PDP1) null mutation produces a lethal infantile phenotype. Hum Genet 2009; 125:319-26. [PMID: 19184109 DOI: 10.1007/s00439-009-0629-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 01/18/2009] [Indexed: 11/30/2022]
Abstract
Pyruvate dehydrogenase phosphatase deficiency has previously only been confirmed at the molecular level in two brothers and two breeds of dog with exercise intolerance. A female patient, who died at 6 months, presented with lactic acidemia in the neonatal period with serum lactate levels ranging from 2.5 to 17 mM. Failure of dichloroacetate to activate the PDH complex in skin fibroblasts was evident, but not in early passages. A homozygous c.277G > T (p.E93X) nonsense mutation in the PDP1 gene was identified in genomic DNA and immunoblotting showed a complete absence of PDP1 protein in mitochondria. Native PDHC activity could be restored by the addition of either recombinant PDP1 or PDP2. This highlights the role of PDP2, the second phosphatase isoform, in PDP1-deficient patients for the first time. We conclude that the severity of the clinical course associated with PDP1 deficiency can be quite variable depending on the exact nature of the molecular defect.
Collapse
Affiliation(s)
- J M Cameron
- The Research Institute, The Hospital for Sick Children, Toronto, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
João Silva M, Pinheiro A, Eusébio F, Gaspar A, Tavares de Almeida I, Rivera I. Pyruvate dehydrogenase deficiency: identification of a novel mutation in the PDHA1 gene which responds to amino acid supplementation. Eur J Pediatr 2009; 168:17-22. [PMID: 18398624 DOI: 10.1007/s00431-008-0700-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2007] [Accepted: 02/18/2008] [Indexed: 11/28/2022]
Abstract
UNLABELLED The pyruvate dehydrogenase complex (PDHc) is an intramitochondrial multienzyme system, which plays a key role in aerobic glucose metabolism by catalysing the oxidative decarboxylation of pyruvate to acetyl-CoA. Genetic defects in the PDHc lead to lactic acidemia and neurological abnormalities. In the majority of the cases, the defect appears to reside in the E(1)alpha subunit, the first catalytic component of the complex. The report is on a 6-year-old Portuguese boy with mild neurological involvement and low PDHc activity with absence of E1alpha on immunoblotting analysis. Molecular studies showed a novel and "de novo" mutation in the PDHA1 gene, R253G. Treatment with arginine aspartate showed complete clinical and biochemical recovery. We hypothesise that arginine aspartate acts as a chemical or pharmacological chaperone, and suggest amino acid supplementation as a possible therapy in PDHA1 mutations with mild phenotypes. CONCLUSION our results encourage the use of amino acid supplementation to overcome the metabolic/biochemical changes induced by PDHA1 gene specific mutations associated with mild PDHc phenotypes.
Collapse
Affiliation(s)
- Maria João Silva
- Unidade de Biologia Molecular e Biopatologia Experimental, Centro de Patogénese Molecular, Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
| | | | | | | | | | | |
Collapse
|
39
|
Gey U, Czupalla C, Hoflack B, Rödel G, Krause-Buchholz U. Yeast pyruvate dehydrogenase complex is regulated by a concerted activity of two kinases and two phosphatases. J Biol Chem 2008; 283:9759-67. [PMID: 18180296 DOI: 10.1074/jbc.m708779200] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of yeast pyruvate dehydrogenase complex is regulated by reversible phosphorylation. Recently we identified two enzymes that are involved in the phosphorylation (Pkp1p) and dephosphorylation (Ppp1p) of Pda1p, the alpha-subunit of the pyruvate dehydrogenase complex. Here we provide evidence that two additional mitochondrial proteins, Pkp2p (Ygl059wp) and Ppp2p (Ycr079wp), are engaged in the regulation of this complex by affecting the phosphorylation state of Pda1p. Our data indicate complementary activities of the kinases and a redundant function for the phosphatases. Both proteins are associated with the complex. We propose a model for the role of the regulatory enzymes and the phosphorylation state of Pda1p in the assembly process of the pyruvate dehydrogenase complex.
Collapse
Affiliation(s)
- Uta Gey
- Institute of Genetics, Dresden University of Technology, 01062 Dresden, Germany
| | | | | | | | | |
Collapse
|
40
|
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.
Collapse
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.
| |
Collapse
|
41
|
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
| | | |
Collapse
|
42
|
Cameron JM, Maj MC, Levandovskiy V, MacKay N, Shelton GD, Robinson BH. Identification of a canine model of pyruvate dehydrogenase phosphatase 1 deficiency. Mol Genet Metab 2007; 90:15-23. [PMID: 17095275 DOI: 10.1016/j.ymgme.2006.09.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 09/26/2006] [Accepted: 09/27/2006] [Indexed: 12/01/2022]
Abstract
Exercise intolerance syndromes are well known to be associated with inborn errors of metabolism affecting glycolysis (phosphorylase and phosphofructokinase deficiency) and fatty acid oxidation (palmitoyl carnitine transferase deficiency). We have identified a canine model for profound exercise intolerance caused by a deficit in PDP1 (EC 3.1.3.43), the phosphatase enzyme that activates the pyruvate dehydrogenase complex (PDHc). The Clumber spaniel breed was originated in 1760 by the Duc de Noailles, as a hunting dog with a gentle temperament suitable for the 'elderly gentleman'. Here we report that 20% of the current Clumber and Sussex spaniel population are carriers for a null mutation in PDP1, and that homozygosity produces severe exercise intolerance. Human pyruvate dehydrogenase phosphatase deficiency was recently characterized at the molecular level. However, the nature of the human mutation (loss of a single amino acid altering PDP1 activity) made it impossible to discern the role of the second phosphatase isoform, PDP2, in the deficient phenotype. Here we show that the null mutation in dogs provides a valuable animal model with which to study the effects of dysregulation of the PDHc. Knowledge of the molecular defect has allowed for the institution of a rapid restriction enzyme test for the canine mutation that will allow for selective breeding and has led to a suggested dietary therapy for affected dogs that has proven to be beneficial. Pharmacological and genetic therapies for PDP1 deficiency can now be investigated and the role of PDP2 can be fully characterized.
Collapse
Affiliation(s)
- Jessie M Cameron
- Metabolic Research Programme, Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, Ont., Canada M5G 1X8
| | | | | | | | | | | |
Collapse
|
43
|
Cameron JM, Levandovskiy V, Mackay N, Raiman J, Renaud DL, Clarke JTR, Feigenbaum A, Elpeleg O, Robinson BH. Novel mutations in dihydrolipoamide dehydrogenase deficiency in two cousins with borderline-normal PDH complex activity. Am J Med Genet A 2006; 140:1542-52. [PMID: 16770810 DOI: 10.1002/ajmg.a.31313] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We have diagnosed dihydrolipoamide dehydrogenase (DLD) deficiency in two male second cousins, who presented with markedly different clinical phenotypes. Patient 1 had a recurrent encephalopathy, and patient 2 had microcephaly and lactic acidosis. Their presentation is unusual, in that the DLD subunit deficiency had little effect on pyruvate dehydrogenase complex activity, but caused a severe reduction in the activities of other enzymes that utilize this subunit. We have identified two mutations in the DLD gene in each patient. The second cousins have one novel mutation in common resulting in a substitution of isoleucine for threonine (I47T), which has not been previously reported in the literature. Patient 1 has a second mutation that has been reported to be common in the Ashkenazi Jewish population, G229C. Patient 2 has a second mutation, E375K, which has also been previously reported in the literature. Enzyme kinetic measurements on patient fibroblasts show that under certain conditions, one heteroallelic mutation may have a higher K(m). This may account for the differing clinical phenotypes. These findings have important repercussions for other patients with similar clinical phenotypes, as DLD activity is not normally measured in cases with normal PDHc activity.
Collapse
Affiliation(s)
- Jessie M Cameron
- Metabolism Research Programme, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Maj MC, Cameron JM, Robinson BH. Pyruvate dehydrogenase phosphatase deficiency: orphan disease or an under-diagnosed condition? Mol Cell Endocrinol 2006; 249:1-9. [PMID: 16574315 DOI: 10.1016/j.mce.2006.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 02/01/2006] [Accepted: 02/05/2006] [Indexed: 11/24/2022]
Abstract
Pyruvate dehydrogenase phosphatase (PDP) is an enzyme which regulates the activity of the pyruvate dehydrogenase complex (PDHc). In the past, PDHc deficiency has been attributed to mutations in the complex itself and the regulatory enzymes have not been considered. We have recently reported the first mutation in PDP1, one of the two isoforms of PDP, which results in severe exercise intolerance and mild developmental delay in patients. This novel process of aberrant pyruvate metabolism opens up a new avenue for investigation into PDHc deficiency, that has hitherto been underappreciated.
Collapse
Affiliation(s)
- M C Maj
- Metabolism Research Programme, Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, Ont., Canada M5G 1X8
| | | | | |
Collapse
|
45
|
Brivet M, Moutard ML, Zater M, Venet L, Chenel C, Mine M, Legrand A. First characterization of a large deletion of the PDHA 1 gene. Mol Genet Metab 2005; 86:456-61. [PMID: 16256390 DOI: 10.1016/j.ymgme.2005.08.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Revised: 08/17/2005] [Accepted: 08/18/2005] [Indexed: 10/25/2022]
Abstract
Pyruvate dehydrogenase complex (PDC) deficiency is one of the major recognized causes of congenital lactic acidosis. The most common form is due to PDHA 1 gene (Xp22.12) defects. Here, we report the case of a Polynesian girl presenting with delayed neurological development, cortical atrophy, and posterior corpus callosum agenesis. Elevated lactate and pyruvate levels in blood and cerebrospinal fluid suggested PDC deficiency. However, PDC activity was within the normal range in lymphocytes and the direct sequencing of the 11 exons and intron-exon junctions of the PDHA 1 gene did not show any changes. Long-range PCR amplification of the whole gene (16 kb) from blood DNA revealed a heterozygous deletion of approximately 4.2kb. Fine mapping of the deletion breakpoint was achieved using purified long-range PCR products for restriction enzyme analysis and direct sequencing. The deletion removed a 4,227 bp region covering part of intron 5 to part of intron 9 [g.10,145_14,371 del 4,227]. The deletion breakpoint contained a short direct repeat (GTAG), which may be derived either from the upstream or the downstream homologous sequence. The presence of a GAG triplet and inverted repeats in the vicinity of the deletion suggest replication slippage at a polymerase alpha arrest site. This is the first time that a large intragenic deletion of the PDHA 1 gene has been characterized.
Collapse
Affiliation(s)
- Michèle Brivet
- Laboratoire de Biochimie 1, AP-HP hôpital de Bicêtre, France.
| | | | | | | | | | | | | |
Collapse
|