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Andersen JV, Marian OC, Qvist FL, Westi EW, Aldana BI, Schousboe A, Don AS, Skotte NH, Wellendorph P. Deficient brain GABA metabolism leads to widespread impairments of astrocyte and oligodendrocyte function. Glia 2024. [PMID: 38899762 DOI: 10.1002/glia.24585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/03/2024] [Accepted: 06/09/2024] [Indexed: 06/21/2024]
Abstract
The neurometabolic disorder succinic semialdehyde dehydrogenase (SSADH) deficiency leads to great neurochemical imbalances and severe neurological manifestations. The cause of the disease is loss of function of the enzyme SSADH, leading to impaired metabolism of the principal inhibitory neurotransmitter GABA. Despite the known identity of the enzymatic deficit, the underlying pathology of SSADH deficiency remains unclear. To uncover new mechanisms of the disease, we performed an untargeted integrative analysis of cerebral protein expression, functional metabolism, and lipid composition in a genetic mouse model of SSADH deficiency (ALDH5A1 knockout mice). Our proteomic analysis revealed a clear regional vulnerability, as protein alterations primarily manifested in the hippocampus and cerebral cortex of the ALDH5A1 knockout mice. These regions displayed aberrant expression of proteins linked to amino acid homeostasis, mitochondria, glial function, and myelination. Stable isotope tracing in acutely isolated brain slices demonstrated an overall maintained oxidative metabolism of glucose, but a selective decrease in astrocyte metabolic activity in the cerebral cortex of ALDH5A1 knockout mice. In contrast, an elevated capacity of oxidative glutamine metabolism was observed in the ALDH5A1 knockout brain, which may serve as a neuronal compensation of impaired astrocyte glutamine provision. In addition to reduced expression of critical oligodendrocyte proteins, a severe depletion of myelin-enriched sphingolipids was found in the brains of ALDH5A1 knockout mice, suggesting degeneration of myelin. Altogether, our study highlights that impaired astrocyte and oligodendrocyte function is intimately linked to SSADH deficiency pathology, suggesting that selective targeting of glial cells may hold therapeutic potential in this disease.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Oana C Marian
- Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
- School of Medical Sciences, The University of Sydney, Camperdown, New South Wales, Australia
| | - Filippa L Qvist
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emil W Westi
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Blanca I Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anthony S Don
- Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
- School of Medical Sciences, The University of Sydney, Camperdown, New South Wales, Australia
| | - Niels H Skotte
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Afshar-Saber W, Teaney NA, Winden KD, Jumo H, Shi X, McGinty G, Hubbs J, Chen C, Tokatly Latzer I, Gasparoli F, Ebrahimi-Fakhari D, Buttermore ED, Roullet JB, Pearl PL, Sahin M. ALDH5A1-deficient iPSC-derived excitatory and inhibitory neurons display cell type specific alterations. Neurobiol Dis 2024; 190:106386. [PMID: 38110041 PMCID: PMC10843729 DOI: 10.1016/j.nbd.2023.106386] [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: 10/10/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 12/20/2023] Open
Abstract
Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a neurometabolic disorder caused by ALDH5A1 mutations presenting with autism and epilepsy. SSADHD leads to impaired GABA metabolism and results in accumulation of GABA and γ-hydroxybutyrate (GHB), which alter neurotransmission and are thought to lead to neurobehavioral symptoms. However, why increased inhibitory neurotransmitters lead to seizures remains unclear. We used induced pluripotent stem cells from SSADHD patients (one female and two male) and differentiated them into GABAergic and glutamatergic neurons. SSADHD iGABA neurons show altered GABA metabolism and concomitant changes in expression of genes associated with inhibitory neurotransmission. In contrast, glutamatergic neurons display increased spontaneous activity and upregulation of mitochondrial genes. CRISPR correction of the pathogenic variants or SSADHD mRNA expression rescue various metabolic and functional abnormalities in human neurons. Our findings uncover a previously unknown role for SSADHD in excitatory human neurons and provide unique insights into the cellular and molecular basis of SSADHD and potential therapeutic interventions.
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Affiliation(s)
- Wardiya Afshar-Saber
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Nicole A Teaney
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kellen D Winden
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Hellen Jumo
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Xutong Shi
- Washington State University, Department of Pharmacotherapy, Spokane, WA, USA
| | - Gabrielle McGinty
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jed Hubbs
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Cidi Chen
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Human Neuron Core, Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Boston, MA, USA
| | - Itay Tokatly Latzer
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | | | - Darius Ebrahimi-Fakhari
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Elizabeth D Buttermore
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Human Neuron Core, Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Boston, MA, USA
| | | | - Phillip L Pearl
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Mustafa Sahin
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; FM Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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3
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Lee HHC, McGinty GE, Pearl PL, Rotenberg A. Understanding the Molecular Mechanisms of Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD): Towards the Development of SSADH-Targeted Medicine. Int J Mol Sci 2022; 23:2606. [PMID: 35269750 PMCID: PMC8910003 DOI: 10.3390/ijms23052606] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 11/21/2022] Open
Abstract
Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a rare genetic disorder caused by inefficient metabolic breakdown of the major inhibitory neurotransmitter, γ-aminobutyric acid (GABA). Pathologic brain accumulation of GABA and γ-hydroxybutyrate (GHB), a neuroactive by-product of GABA catabolism, leads to a multitude of molecular abnormalities beginning in early life, culminating in multifaceted clinical presentations including delayed psychomotor development, intellectual disability, hypotonia, and ataxia. Paradoxically, over half of patients with SSADHD also develop epilepsy and face a significant risk of sudden unexpected death in epilepsy (SUDEP). Here, we review some of the relevant molecular mechanisms through which impaired synaptic inhibition, astrocytic malfunctions and myelin defects might contribute to the complex SSADHD phenotype. We also discuss the gaps in knowledge that need to be addressed for the implementation of successful gene and enzyme replacement SSADHD therapies. We conclude with a description of a novel SSADHD mouse model that enables 'on-demand' SSADH restoration, allowing proof-of-concept studies to fine-tune SSADH restoration in preparation for eventual human trials.
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Affiliation(s)
- Henry H. C. Lee
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA 02115, USA; (G.E.M.); (A.R.)
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Gabrielle E. McGinty
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA 02115, USA; (G.E.M.); (A.R.)
| | - Phillip L. Pearl
- Division of Epilepsy & Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital, Boston, MA 02115, USA;
| | - Alexander Rotenberg
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA 02115, USA; (G.E.M.); (A.R.)
- Division of Epilepsy & Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital, Boston, MA 02115, USA;
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4
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Ahmadi ZZ, DiBacco ML, Pearl PL. Speech Motor Function and Auditory Perception in Succinic Semialdehyde Dehydrogenase Deficiency: Toward Pre-Supplementary Motor Area (SMA) and SMA-Proper Dysfunctions. J Child Neurol 2021; 36:1210-1217. [PMID: 33757330 DOI: 10.1177/08830738211001210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study reviews the fundamental roles of pre-supplementary motor area (SMA) and SMA-proper responsible for speech-motor functions and auditory perception in succinic semialdehyde dehydrogenase (SSADH) deficiency. We comprehensively searched the databases of PubMed, Google Scholar, and the electronic journals Springer, PreQuest, and Science Direct associated with keywords SSADHD, SMA, auditory perception, speech, and motor with AND operator. Transcranial magnetic stimulation emerged for assessing excitability/inhibitory M1 functions, but its role in pre-SMA and SMA proper dysfunction remains unknown. There was a lack of data on resting-state and task-based functional magnetic resonance imaging (MRI), with a focus on passive and active tasks for both speech and music, in terms of analysis of SMA-related cortex and its connections. Children with SSADH deficiency likely experience a dysfunction in connectivity between SMA portions with cortical and subcortical areas contributing to disabilities in speech-motor functions and auditory perception. Early diagnosis of auditory-motor disabilities in children with SSADH deficiency by neuroimaging techniques invites opportunities for utilizing sensory-motor integration as future interventional strategies.
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Affiliation(s)
- Zohreh Ziatabar Ahmadi
- Department of Speech Therapy, School of Rehabilitation, Babol University of Medical Sciences, Babol, I.R. Iran
| | - Melissa L DiBacco
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Phillip L Pearl
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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5
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Walters DC, Lawrence R, Kirby T, Ahrendsen JT, Anderson MP, Roullet JB, Murphy EJ, Gibson KM. Postmortem Analyses in a Patient With Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD): II. Histological, Lipid, and Gene Expression Outcomes in Regional Brain Tissue. J Child Neurol 2021; 36:1177-1188. [PMID: 33557678 PMCID: PMC8349921 DOI: 10.1177/0883073820987742] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This study has extended previous metabolic measures in postmortem tissues (frontal and parietal lobes, pons, cerebellum, hippocampus, and cerebral cortex) obtained from a 37-year-old male patient with succinic semialdehyde dehydrogenase deficiency (SSADHD) who expired from SUDEP (sudden unexplained death in epilepsy). Histopathologic characterization of fixed cortex and hippocampus revealed mild to moderate astrogliosis, especially in white matter. Analysis of total phospholipid mass in all sections of the patient revealed a 61% increase in cortex and 51% decrease in hippocampus as compared to (n = 2-4) approximately age-matched controls. Examination of mass and molar composition of major phospholipid classes showed decreases in phospholipids enriched in myelin, such as phosphatidylserine, sphingomyelin, and ethanolamine plasmalogen. Evaluation of gene expression (RT2 Profiler PCR Arrays, GABA, glutamate; Qiagen) revealed dysregulation in 14/15 GABAA receptor subunits in cerebellum, parietal, and frontal lobes with the most significant downregulation in ∊, θ, ρ1, and ρ2 subunits (7.7-9.9-fold). GABAB receptor subunits were largely unaffected, as were ionotropic glutamate receptors. The metabotropic glutamate receptor 6 was consistently downregulated (maximum 5.9-fold) as was the neurotransmitter transporter (GABA), member 13 (maximum 7.3-fold). For other genes, consistent dysregulation was seen for interleukin 1β (maximum downregulation 9.9-fold) and synuclein α (maximal upregulation 6.5-fold). Our data provide unique insight into SSADHD brain function, confirming astrogliosis and lipid abnormalities previously observed in the null mouse model while highlighting long-term effects on GABAergic/glutamatergic gene expression in this disorder.
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Affiliation(s)
- DC Walters
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA
| | - R Lawrence
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND
| | - T Kirby
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA
| | - JT Ahrendsen
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - MP Anderson
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - J-B Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA
| | - EJ Murphy
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND
| | - KM Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA,Correspondence: Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Health Sciences Building Room 210C, Washington State University, 412 E. Spokane Falls Boulevard, Spokane, WA 99202-2131; phone 509-358-7954; fax 508-358-7667;
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6
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Karapiperis C, Chasapi A, Angelis L, Scouras ZG, Mastroberardino PG, Tapio S, Atkinson MJ, Ouzounis CA. The Coming of Age for Big Data in Systems Radiobiology, an Engineering Perspective. BIG DATA 2021; 9:63-71. [PMID: 32991205 DOI: 10.1089/big.2019.0144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
As high-throughput approaches in biological and biomedical research are transforming the life sciences into information-driven disciplines, modern analytics platforms for big data have started to address the needs for efficient and systematic data analysis and interpretation. We observe that radiobiology is following this general trend, with -omics information providing unparalleled depth into the biomolecular mechanisms of radiation response-defined as systems radiobiology. We outline the design of computational frameworks and discuss the analysis of big data in low-dose ionizing radiation (LDIR) responses of the mammalian brain. Following successful examples and best practices of approaches for the analysis of big data in life sciences and health care, we present the needs and requirements for radiation research. Our goal is to raise awareness for the radiobiology community about the new technological possibilities that can capture complex information and execute data analytics on a large scale. The production of large data sets from genome-wide experiments (quantity) and the complexity of radiation research with multidimensional experimental designs (quality) will necessitate the adoption of latest information technologies. The main objective was to translate research results into applied clinical and epidemiological practice and understand the responses of biological tissues to LDIR to define new radiation protection policies. We envisage a future where multidisciplinary teams include data scientists, artificial intelligence experts, DevOps engineers, and of course radiation experts to fulfill the augmented needs of the radiobiology community, accelerate research, and devise new strategies.
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Affiliation(s)
- Christos Karapiperis
- School of Informatics, Aristotle University of Thessalonica (AUTH), Thessalonica, Greece
| | - Anastasia Chasapi
- Biological Computation & Process Laboratory (BCPL), Chemical Process & Energy Resources Institute (CPERI), Centre for Research & Technology Hellas (CERTH), Thessalonica, Greece
| | - Lefteris Angelis
- School of Informatics, Aristotle University of Thessalonica (AUTH), Thessalonica, Greece
| | - Zacharias G Scouras
- School of Biology, Aristotle University of Thessalonica (AUTH), Thessalonica, Greece
| | | | - Soile Tapio
- Institute of Radiation Biology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (HMGU), Neuherberg, Germany
| | - Michael J Atkinson
- Institute of Radiation Biology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (HMGU), Neuherberg, Germany
| | - Christos A Ouzounis
- School of Informatics, Aristotle University of Thessalonica (AUTH), Thessalonica, Greece
- Biological Computation & Process Laboratory (BCPL), Chemical Process & Energy Resources Institute (CPERI), Centre for Research & Technology Hellas (CERTH), Thessalonica, Greece
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7
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Brown MN, Gibson KM, Schmidt MA, Walters DC, Arning E, Bottiglieri T, Roullet J. Cellular and molecular outcomes of glutamine supplementation in the brain of succinic semialdehyde dehydrogenase-deficient mice. JIMD Rep 2020; 56:58-69. [PMID: 33204597 PMCID: PMC7653255 DOI: 10.1002/jmd2.12151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 12/24/2022] Open
Abstract
Succinic semialdehyde dehydrogenase deficiency (SSADHD) manifests with low levels of glutamine in the brain, suggesting that central glutamine deficiency contributes to pathogenesis. Recently, we attempted to rescue the disease phenotype of aldh5a1 -/- mice, a murine model of SSADHD with dietary glutamine supplementation. No clinical rescue and no central glutamine improvement were observed. Here, we report the results of follow-up studies of the cellular and molecular basis of the resistance of the brain to glutamine supplementation. We first determined if the expression of genes involved in glutamine metabolism was impacted by glutamine feeding. We then searched for changes of brain histology in response to glutamine supplementation, with a focus on astrocytes, known regulators of glutamine synthesis in the brain. Glutamine supplementation significantly modified the expression of glutaminase (gls) (0.6-fold down), glutamine synthetase (glul) (1.5-fold up), and glutamine transporters (solute carrier family 7, member 5 [slc7a5], 2.5-fold up; slc38a2, 0.6-fold down). The number of GLUL-labeled cells was greater in the glutamine-supplemented group than in controls (P < .05). Reactive astrogliosis, a hallmark of brain inflammation in SSADHD, was confirmed. We observed a 2-fold stronger astrocyte staining in mutants than in wild-type controls (optical density/cell were 1.8 ± 0.08 in aldh5a1 -/- and 0.99 ± 0.06 in aldh5a1 +/+ ; P < .0001), and a 3-fold higher expression of gfap and vimentin. However, glutamine supplementation did not improve the histological and molecular signature of astrogliosis. Thus, glutamine supplementation impacts genes implicated in central glutamine homeostasis without improving reactive astrogliosis. The mechanisms underlying glutamine deficiency and its contribution to SSADHD pathogenesis remain unknown and should be the focus of future investigations.
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Affiliation(s)
- Madalyn N. Brown
- Department of PharmacotherapyCollege of Pharmacy and Pharmaceutical Sciences, Washington State UniversitySpokaneWashingtonUSA
| | - K. Michael Gibson
- Department of PharmacotherapyCollege of Pharmacy and Pharmaceutical Sciences, Washington State UniversitySpokaneWashingtonUSA
| | - Michelle A. Schmidt
- Department of PharmacotherapyCollege of Pharmacy and Pharmaceutical Sciences, Washington State UniversitySpokaneWashingtonUSA
| | - Dana C. Walters
- Department of PharmacotherapyCollege of Pharmacy and Pharmaceutical Sciences, Washington State UniversitySpokaneWashingtonUSA
| | - Erland Arning
- Baylor Scott and White Research InstituteInstitute of Metabolic DiseaseDallasTexasUSA
| | - Teodoro Bottiglieri
- Baylor Scott and White Research InstituteInstitute of Metabolic DiseaseDallasTexasUSA
| | - Jean‐Baptiste Roullet
- Department of PharmacotherapyCollege of Pharmacy and Pharmaceutical Sciences, Washington State UniversitySpokaneWashingtonUSA
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Novel biomarkers and age-related metabolite correlations in plasma and dried blood spots from patients with succinic semialdehyde dehydrogenase deficiency. Orphanet J Rare Dis 2020; 15:261. [PMID: 32967698 PMCID: PMC7510106 DOI: 10.1186/s13023-020-01522-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 08/24/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Previous work has identified age-related negative correlations for γ-hydroxybutyric acid (GHB) and γ-aminobutyric acid (GABA) in plasma of patients with succinic semialdehyde dehydrogenase deficiency (SSADHD). Using plasma and dried blood spots (DBS) collected in an ongoing natural history study, we tested the hypothesis that other biomarkers would follow a similar age-related negative correlation as seen for GHB/GABA. Samples (mixed sex) included: patients (n = 21 unique samples, 1-39.5 yrs) and parallel controls (n = 9 unique samples, 8.4-34.8 yrs). Archival control data (DBS only; n = 171, 0.5-39.9 yrs) was also included. RESULTS Metabolites assessed included amino acids (plasma, DBS) and acylcarnitines, creatine, creatinine, and guanidinoacetate (DBS only). Age-related negative correlations for glycine (plasma, DBS) and sarcosine (N-methylglycine, plasma) were detected, accompanied by elevated proline and decreased levels of succinylacetone, argininosuccinate, formaminoglutamate, and creatinine. Significantly low acylcarnitines were detected in patients across all chain lengths (short-, medium- and long-chain). Significant age-dependent positive correlations for selected acylcarnitines (C6-, C12DC(dicarboxylic)-, C16-, C16:1-, C18:1-, C18:2OH-carnitines) were detected in patients and absent in controls. Receiver operating characteristic (ROC) curves for all binary comparisons revealed argininosuccinate and succinylacetone to be the most discriminating biomarkers (area > 0.92). CONCLUSIONS Age-dependent acylcarnitine correlations may represent metabolic compensation responsive to age-related changes in GHB and GABA. Our study highlights novel biomarkers in SSADHD and expands the metabolic pathophysiology of this rare disorder of GABA metabolism.
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Brown M, Turgeon C, Rinaldo P, Pop A, Salomons GS, Roullet J, Gibson KM. Longitudinal metabolomics in dried bloodspots yields profiles informing newborn screening for succinic semialdehyde dehydrogenase deficiency. JIMD Rep 2020; 53:29-38. [PMID: 32395407 PMCID: PMC7203655 DOI: 10.1002/jmd2.12075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 12/23/2022] Open
Abstract
Analyses of 19 amino acids, 38 acylcarnitines, and 3 creatine analogues (https://clir.mayo.edu) were implemented to test the hypothesis that succinic semialdehyde dehydrogenase deficiency (SSADHD) could be identified in dried bloodspots (DBS) using currently available newborn screening methodology. The study population included 17 post-newborn SSADHD DBS (age range 0.8-38 years; median, 8.2 years; 10 M; controls, 129-353 age-matched individuals, mixed gender) and 10 newborn SSADHD DBS (including first and second screens from 3 of 7 patients). Low (informative) markers in post-newborn DBS included C2- and C4-OH carnitines, ornithine, histidine and creatine, with no gender differences. For newborn DBS, informative markers included C2-, C3-, C4- and C4-OH carnitines, creatine and ornithine. Of these, only creatine demonstrated a significant change with age, revealing an approximate 4-fold decrease. We conclude that quantitation of short-chain acylcarnitines, creatine, and ornithine provides a newborn DBS profile with potential as a first tier screening tool for early detection of SSADHD. This first tier evaluation can be readily verified using a previously described second tier liquid chromatography-tandem mass spectrometry method for γ-hydroxybutyric acid in the same DBS. More extensive evaluation of this first/second tier screening approach is needed in a larger population.
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Affiliation(s)
- Madalyn Brown
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical SciencesWashington State UniversitySpokaneWashington
| | - Coleman Turgeon
- Mayo Clinic, Department of Laboratory Medicine and PathologyRochesterMinnesota
| | - Piero Rinaldo
- Mayo Clinic, Department of Laboratory Medicine and PathologyRochesterMinnesota
| | - Ana Pop
- Metabolic Unit, Department of Clinical Chemistry, Amsterdam University Medical CentersVrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam Gastroenterology & MetabolismAmsterdamThe Netherlands
| | - Gajja S. Salomons
- Metabolic Unit, Department of Clinical Chemistry, Amsterdam University Medical CentersVrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam Gastroenterology & MetabolismAmsterdamThe Netherlands
- Department of Genetic Metabolic Diseases, Amsterdam University Medical CentersUniversity of Amsterdam, Amsterdam Neuroscience, Amsterdam Gastroenterology & MetabolismAmsterdamThe Netherlands
| | - Jean‐Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical SciencesWashington State UniversitySpokaneWashington
| | - K. Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical SciencesWashington State UniversitySpokaneWashington
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10
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Kirby T, Walters DC, Brown M, Jansen E, Salomons GS, Turgeon C, Rinaldo P, Arning E, Ashcraft P, Bottiglieri T, Roullet JB, Gibson KM. Post-mortem tissue analyses in a patient with succinic semialdehyde dehydrogenase deficiency (SSADHD). I. Metabolomic outcomes. Metab Brain Dis 2020; 35:601-614. [PMID: 32172518 PMCID: PMC7180121 DOI: 10.1007/s11011-020-00550-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 02/12/2020] [Indexed: 12/14/2022]
Abstract
Metabolomic characterization of post-mortem tissues (frontal and parietal cortices, pons, cerebellum, hippocampus, cerebral cortex, liver and kidney) derived from a 37 y.o. male patient with succinic semialdehyde dehydrogenase deficiency (SSADHD) was performed in conjunction with four parallel series of control tissues. Amino acids, acylcarnitines, guanidino- species (guanidinoacetic acid, creatine, creatinine) and GABA-related intermediates were quantified using UPLC and mass spectrometric methods that included isotopically labeled internal standards. Amino acid analyses revealed significant elevation of aspartic acid and depletion of glutamine in patient tissues. Evidence for disruption of short-chain fatty acid metabolism, manifest as altered C4OH, C5, C5:1, C5DC (dicarboxylic) and C12OH carnitines, was observed. Creatine and guanidinoacetic acids were decreased and elevated, respectively. GABA-associated metabolites (total GABA, γ-hydroxybutyric acid, succinic semialdehyde, 4-guanidinobutyrate, 4,5-dihydroxyhexanoic acid and homocarnosine) were significantly increased in patient tissues, including liver and kidney. The data support disruption of fat, creatine and amino acid metabolism as a component of the pathophysiology of SSADHD, and underscore the observation that metabolites measured in patient physiological fluids provide an unreliable reflection of brain metabolism.
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Affiliation(s)
- Trevor Kirby
- Department of Pharmacotherapy, Health Sciences Building Room 210C, College of Pharmacy and Pharmaceutical Sciences, Washington State University, 412 E. Spokane Falls Boulevard, Spokane, WA, 99202-2131, USA
| | - Dana C Walters
- Department of Pharmacotherapy, Health Sciences Building Room 210C, College of Pharmacy and Pharmaceutical Sciences, Washington State University, 412 E. Spokane Falls Boulevard, Spokane, WA, 99202-2131, USA
| | - Madalyn Brown
- Department of Pharmacotherapy, Health Sciences Building Room 210C, College of Pharmacy and Pharmaceutical Sciences, Washington State University, 412 E. Spokane Falls Boulevard, Spokane, WA, 99202-2131, USA
| | - Erwin Jansen
- Department of Clinical Chemistry, Metabolic Unit, Amsterdam University Medical Center (Amsterdam UMC) and VU University Medical Center (VUmc), Amsterdam, the Netherlands
| | - Gajja S Salomons
- Department of Clinical Chemistry, Metabolic Unit, Amsterdam University Medical Center (Amsterdam UMC) and VU University Medical Center (VUmc), Amsterdam, the Netherlands
| | - Coleman Turgeon
- Biochemical Genetics Laboratory, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Piero Rinaldo
- Biochemical Genetics Laboratory, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Erland Arning
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Paula Ashcraft
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Teodoro Bottiglieri
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, Health Sciences Building Room 210C, College of Pharmacy and Pharmaceutical Sciences, Washington State University, 412 E. Spokane Falls Boulevard, Spokane, WA, 99202-2131, USA
| | - K Michael Gibson
- Department of Pharmacotherapy, Health Sciences Building Room 210C, College of Pharmacy and Pharmaceutical Sciences, Washington State University, 412 E. Spokane Falls Boulevard, Spokane, WA, 99202-2131, USA.
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11
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Perry CJ, Finch P, Müller‐Taubenberger A, Leung K, Warren EC, Damstra‐Oddy J, Sharma D, Patra PH, Glyn S, Boberska J, Stewart B, Baldwin A, Piscitelli F, Harvey RJ, Harwood A, Thompson C, Claus SP, Greene ND, McNeish AJ, Williams CM, Whalley BJ, Williams RS. A new mechanism for cannabidiol in regulating the one-carbon cycle and methionine levels in Dictyostelium and in mammalian epilepsy models. Br J Pharmacol 2020; 177:912-928. [PMID: 31693171 PMCID: PMC7024701 DOI: 10.1111/bph.14892] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 09/06/2019] [Accepted: 09/17/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Epidiolex™, a form of highly purified cannabidiol (CBD) derived from Cannabis plants, has demonstrated seizure control activity in patients with Dravet syndrome, without a fully elucidated mechanism of action. We have employed an unbiased approach to investigate this mechanism at a cellular level. EXPERIMENTAL APPROACH We use a tractable biomedical model organism, Dictyostelium, to identify a protein controlling the effect of CBD and characterize this mechanism. We then translate these results to a Dravet syndrome mouse model and an acute in vitro seizure model. KEY RESULTS CBD activity is partially dependent upon the mitochondrial glycine cleavage system component, GcvH1 in Dictyostelium, orthologous to the human glycine cleavage system component H protein, which is functionally linked to folate one-carbon metabolism (FOCM). Analysis of FOCM components identified a mechanism for CBD in directly inhibiting methionine synthesis. Analysis of brain tissue from a Dravet syndrome mouse model also showed drastically altered levels of one-carbon components including methionine, and an in vitro rat seizure model showed an elevated level of methionine that is attenuated following CBD treatment. CONCLUSIONS AND IMPLICATIONS Our results suggest a novel mechanism for CBD in the regulating methionine levels and identify altered one-carbon metabolism in Dravet syndrome and seizure activity.
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Affiliation(s)
- Christopher J. Perry
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
| | - Paul Finch
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
| | | | - Kit‐Yi Leung
- Development Biology and Cancer ProgramUCL Great Ormond Street Institute of Child HealthLondonUK
| | - Eleanor C. Warren
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
| | - Joseph Damstra‐Oddy
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
| | - Devdutt Sharma
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
| | - Pabitra H. Patra
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Sarah Glyn
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Joanna Boberska
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Balint Stewart
- Faculty of Life SciencesManchester UniversityManchesterUK
| | - Amy Baldwin
- Neuroscience and Mental Health Research InstituteCardiff UniversityCardiffUK
| | - Fabiana Piscitelli
- Institute of Biomolecular ChemistryConsiglio Nazionale delle RicercheRomeItaly
| | - Robert J. Harvey
- School of Health and Sport SciencesUniversity of the Sunshine CoastSippy DownsQLDAustralia
- Sunshine Coast Health InstituteUniversity of the Sunshine CoastBirtinyaQLDAustralia
| | - Adrian Harwood
- Neuroscience and Mental Health Research InstituteCardiff UniversityCardiffUK
| | | | - Sandrine P. Claus
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Nicholas D.E. Greene
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Alister J. McNeish
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Claire M. Williams
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Benjamin J. Whalley
- The School of Chemistry, Food Biosciences and PharmacyUniversity of ReadingReadingUK
| | - Robin S.B. Williams
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
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12
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Brown M, Turgeon C, Rinaldo P, Roullet JB, Gibson KM. Temporal metabolomics in dried bloodspots suggests multipathway disruptions in aldh5a1 -/- mice, a model of succinic semialdehyde dehydrogenase deficiency. Mol Genet Metab 2019; 128:397-408. [PMID: 31699650 DOI: 10.1016/j.ymgme.2019.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 08/26/2019] [Accepted: 10/05/2019] [Indexed: 02/08/2023]
Abstract
Succinic semialdehyde dehydrogenase (SSADH) deficiency (SSADHD; OMIM 271980) is a rare disorder featuring accumulation of neuroactive 4-aminobutyric acid (GABA; γ-aminobutyric acid, derived from glutamic acid) and 4-hydroxybutyric acid (γ-hydroxybutyric acid; GHB, a short-chain fatty acid analogue of GABA). Elevated GABA is predicted to disrupt the GABA shunt linking GABA transamination to the Krebs cycle and maintaining the balance of excitatory:inhibitory neurotransmitters. Similarly, GHB (or a metabolite) is predicted to impact β-oxidation flux. We explored these possibilities employing temporal metabolomics of dried bloodspots (DBS), quantifying amino acids, acylcarnitines, and guanidino- metabolites, derived from aldh5a1+/+, aldh5a1+/- and aldh5a1-/- mice (aldehyde dehydrogenase 5a1 = SSADH) at day of life (DOL) 20 and 42 days. At DOL 20, aldh5a1-/- mice had elevated C6 dicarboxylic (adipic acid) and C14 carnitines and threonine, combined with a significantly elevated ratio of threonine/[aspartic acid + alanine], in comparison to aldh5a1+/+ mice. Conversely, at DOL 42 aldh5a1-/- mice manifested decreased short chain carnitines (C0-C6), valine and glutamine, in comparison to aldh5a1+/+ mice. Guanidino species, including creatinine, creatine and guanidinoacetic acid, evolved from normal levels (DOL 20) to significantly decreased values at DOL 42 in aldh5a1-/- as compared to aldh5a1+/+ mice. Our results provide a novel temporal snapshot of the evolving metabolic profile of aldh5a1-/- mice while highlighting new pathomechanisms in SSADHD.
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Affiliation(s)
- Madalyn Brown
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, United States of America
| | - Coleman Turgeon
- Biochemical Genetics Laboratory, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States of America
| | - Piero Rinaldo
- Biochemical Genetics Laboratory, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States of America
| | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, United States of America
| | - K Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, United States of America.
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13
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Brown MN, Walters DC, Schmidt MA, Hill J, McConnell A, Jansen EEW, Salomons GS, Arning E, Bottiglieri T, Gibson KM, Roullet JB. Maternal glutamine supplementation in murine succinic semialdehyde dehydrogenase deficiency, a disorder of γ-aminobutyric acid metabolism. J Inherit Metab Dis 2019; 42:1030-1039. [PMID: 31032972 DOI: 10.1002/jimd.12107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/29/2019] [Accepted: 04/25/2019] [Indexed: 11/09/2022]
Abstract
Murine succinic semialdehyde dehydrogenase deficiency (SSADHD) manifests with high concentrations of γ-aminobutyric acid (GABA) and γ-hydroxybutyrate (GHB) and low glutamine in the brain. To understand the pathogenic contribution of central glutamine deficiency, we exposed aldh5a1-/- (SSADHD) mice and their genetic controls (aldh5a1+/+ ) to either a 4% (w/w) glutamine-containing diet or a glutamine-free diet from conception until postnatal day 30. Endpoints included brain, liver and blood amino acids, brain GHB, ataxia scores, and open field testing. Glutamine supplementation did not improve aldh5a1-/- brain glutamine deficiency nor brain GABA and GHB. It decreased brain glutamate but did not change the ratio of excitatory (glutamate) to inhibitory (GABA) neurotransmitters. In contrast, glutamine supplementation significantly increased brain arginine (30% for aldh5a1+/+ and 18% for aldh5a1-/- mice), and leucine (12% and 18%). Glutamine deficiency was confirmed in the liver. The test diet increased hepatic glutamate in both genotypes, decreased glutamine in aldh5a1+/+ but not in aldh5a1-/- , but had no effect on GABA. Dried bloodspot analyses showed significantly elevated GABA in mutants (approximately 800% above controls) and decreased glutamate (approximately 25%), but no glutamine difference with controls. Glutamine supplementation did not impact blood GABA but significantly increased glutamine and glutamate in both genotypes indicating systemic exposure to dietary glutamine. Ataxia and pronounced hyperactivity were observed in aldh5a1-/- mice but remained unchanged by the diet intervention. The study suggests that glutamine supplementation improves peripheral but not central glutamine deficiency in experimental SSADHD. Future studies are needed to fully understand the pathogenic role of brain glutamine deficiency in SSADHD.
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Affiliation(s)
- Madalyn N Brown
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Dana C Walters
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Michelle A Schmidt
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, Washington
| | | | | | - Erwin E W Jansen
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center & Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Gajja S Salomons
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center & Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Erland Arning
- Baylor Scott and White Research Institute, Institute of Metabolic Disease, Dallas, Texas
| | - Teodoro Bottiglieri
- Baylor Scott and White Research Institute, Institute of Metabolic Disease, Dallas, Texas
| | - K Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
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14
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Vogel KR, Ainslie GR, Walters DC, McConnell A, Dhamne SC, Rotenberg A, Roullet JB, Gibson KM. Succinic semialdehyde dehydrogenase deficiency, a disorder of GABA metabolism: an update on pharmacological and enzyme-replacement therapeutic strategies. J Inherit Metab Dis 2018; 41:699-708. [PMID: 29460030 PMCID: PMC6041169 DOI: 10.1007/s10545-018-0153-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/29/2018] [Accepted: 01/31/2018] [Indexed: 12/16/2022]
Abstract
We present an update to the status of research on succinic semialdehyde dehydrogenase (SSADH) deficiency (SSADHD), a rare disorder of GABA metabolism. This is an unusual disorder featuring the accumulation of both GABA and its neuromodulatory analog, gamma-hydroxybutyric acid (GHB), and recent studies have advanced the potential clinical application of NCS-382, a putative GHB receptor antagonist. Animal studies have provided proof-of-concept that enzyme replacement therapy could represent a long-term therapeutic option. The characterization of neuronal stem cells (NSCs) derived from aldehyde dehydrogenase 5a1-/- (aldh5a1-/-) mice, the murine model of SSADHD, has highlighted NSC utility as an in vitro system in which to study therapeutics and associated toxicological properties. Gene expression analyses have revealed that transcripts encoding GABAA receptors are down-regulated and may remain largely immature in aldh5a1-/- brain, characterized by excitatory as opposed to inhibitory outputs, the latter being the expected action in the mature central nervous system. This indicates that agents altering chloride channel activity may be therapeutically relevant in SSADHD. The most recent therapeutic prospects include mTOR (mechanistic target of rapamycin) inhibitors, drugs that have received attention with the elucidation of the effects of elevated GABA on autophagy. The outlook for novel therapeutic trials in SSADHD continues to improve.
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Affiliation(s)
- Kara R Vogel
- Department of Neuroscience, University of Wisconsin, Madison, WI, USA
| | | | - Dana C Walters
- Department of Pharmacotherapy, College of Pharmacy, Washington State University, 412 E. Spokane Falls Blvd, Health Sciences Building Room 210, Spokane, WA, 99204, USA
| | | | - Sameer C Dhamne
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Alexander Rotenberg
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy, Washington State University, 412 E. Spokane Falls Blvd, Health Sciences Building Room 210, Spokane, WA, 99204, USA
| | - K Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy, Washington State University, 412 E. Spokane Falls Blvd, Health Sciences Building Room 210, Spokane, WA, 99204, USA.
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15
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Menduti G, Biamino E, Vittorini R, Vesco S, Puccinelli MP, Porta F, Capo C, Leo S, Ciminelli BM, Iacovelli F, Spada M, Falconi M, Malaspina P, Rossi L. Succinic semialdehyde dehydrogenase deficiency: The combination of a novel ALDH5A1 gene mutation and a missense SNP strongly affects SSADH enzyme activity and stability. Mol Genet Metab 2018; 124:210-215. [PMID: 29895405 DOI: 10.1016/j.ymgme.2018.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/28/2018] [Accepted: 05/30/2018] [Indexed: 02/06/2023]
Abstract
Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a rare autosomal recessive metabolic disorder of GABA catabolism. SSADH is a mitochondrial homotetrameric enzyme encoded by ALDH5A1 gene. We report the molecular characterization of ALDH5A1 gene in an Italian SSADHD patient, showing heterozygosity for four missense mutations: c.526G>A (p.G176R), c.538C>T (p.H180Y), c.709G>T (p.A237S) and c.1267A>T (p.T423S), the latter never described so far. The patient inherited c.526A in cis with c.538T from the mother and c.709T in cis with c.1267T from the father. To explore the effects of the two allelic arrangements on SSADH activity and protein level, wild type, single or double mutated cDNA constructs were expressed in a cell system. The p.G176R change, alone or in combination with p.H180Y, causes the abolishment of enzyme activity. Western blot analysis showed a strongly reduced amount of the p.176R-p.180Y double mutant protein, suggesting increased degradation. Indeed, in silico analyses confirmed high instability of this mutant homotetramer. Enzyme activity relative to the other p.423S-p.237S double mutant is around 30% of wt. Further in silico analyses on all the possible combinations of mutant monomers suggest the lowest stability for the tetramer constituted by p.176R-p.180Y monomers and the highest stability for that constituted by p.237S-p.423S monomers. The present study shows that when a common SNP, associated with a slight reduction of SSADH activity, is inherited in cis with a mutation showing no consequences on the enzyme function, the activity is strongly affected. In conclusion, the peculiar arrangement of four missense mutations occurring in this patient is responsible for the SSADHD phenotype.
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Affiliation(s)
| | - Elisa Biamino
- Department of Pediatrics, University of Turin, Italy
| | - Roberta Vittorini
- Department of Pediatric Neurology, Regina Margherita Children Hospital, University of Turin, Italy
| | - Serena Vesco
- Department of Pediatric Neurology, Regina Margherita Children Hospital, University of Turin, Italy
| | - Maria Paola Puccinelli
- Department of Laboratory Medicine, Azienda Ospedaliera Città della Salute e della Scienza, Turin, Italy
| | | | - Concetta Capo
- Department of Biology, University of Rome Tor Vergata, Italy
| | - Sara Leo
- Department of Biology, University of Rome Tor Vergata, Italy
| | | | | | - Marco Spada
- Department of Pediatrics, University of Turin, Italy
| | - Mattia Falconi
- Department of Biology, University of Rome Tor Vergata, Italy
| | | | - Luisa Rossi
- Department of Biology, University of Rome Tor Vergata, Italy.
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16
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Benke D, Möhler H. Impact on GABA systems in monogenetic developmental CNS disorders: Clues to symptomatic treatment. Neuropharmacology 2017; 136:46-55. [PMID: 28764992 DOI: 10.1016/j.neuropharm.2017.07.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 07/26/2017] [Accepted: 07/28/2017] [Indexed: 12/26/2022]
Abstract
Animal studies of several single-gene disorders demonstrate that reversing the molecular signaling deficits can result in substantial symptomatic improvements in function. Focusing on the ratio of excitation to inhibition as a potential pathophysiological hallmark, seven single-gene developmental CNS disorders are reviewed which are characterized by a striking dysregulation of neuronal inhibition. Deficits in inhibition and excessive inhibition are found. The examples of developmental disorders encompass Neurofibromatosis type 1, Fragile X syndrome, Rett syndrome, Dravet syndrome including autism-like behavior, NONO-mutation-induced intellectual disability, Succinic semialdehyde dehydrogenase deficiency and Congenital nystagmus due to FRMD7 mutations. The phenotype/genotype correlations observed in animal models point to potential treatment options and will continue to inspire clinical research. Three drugs are presently in clinical trials: acamprosate and ganoxolon for Fragile X syndrome and SGS-742 for SSADH deficiency. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Dietmar Benke
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Drug Discovery Network Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Hanns Möhler
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH), Vladimir-Prelog-Weg 10, 8023 Zurich, Switzerland.
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17
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Vogel KR, Ainslie GR, Gibson KM. mTOR inhibitors rescue premature lethality and attenuate dysregulation of GABAergic/glutamatergic transcription in murine succinate semialdehyde dehydrogenase deficiency (SSADHD), a disorder of GABA metabolism. J Inherit Metab Dis 2016; 39:877-886. [PMID: 27518770 PMCID: PMC5114712 DOI: 10.1007/s10545-016-9959-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/15/2016] [Accepted: 06/21/2016] [Indexed: 02/07/2023]
Abstract
Recent studies have identified a role for supraphysiological gamma-aminobutyric acid (GABA) in the regulation of mechanistic target of rapamycin (mTOR), a protein kinase with pleiotropic roles in cellular development and homeostasis, including integration of growth factors and nutrient sensing and synaptic input in neurons (Lakhani et al. 2014; Vogel et al. 2015). Aldehyde dehydrogenase 5a1-deficient (aldh5a1 -/- ) mice, the murine orthologue of human succinic semialdehyde dehydrogenase deficiency (SSADHD), manifest increased GABA that disrupts mitophagy and increases mitochondria number with enhanced oxidant stress. Treatment with the mTOR inhibitor, rapamycin, significantly attenuates these GABA-related anomalies. We extend those studies through characterization of additional rapamycin analog (rapalog) agents including temsirolimus, dual mTOR inhibitors [Torin 1 and 2 (Tor 1/ Tor 2), Ku-0063794, and XL-765], as well as mTOR-independent autophagy inducers [trehalose, tat-Beclin 1, tacrolimus (FK-506), and NF-449) in aldh5a1 -/- mice. Rapamycin, Tor 1, and Tor 2 rescued these mice from premature lethality associated with status epilepticus. XL-765 extended lifespan significantly and induced weight gain in aldh5a1 -/- mice; untreated aldh5a1 -/- mice failed to increase body mass. Expression profiling of animals rescued with Tor 1/Tor 2 and XL-765 revealed multiple instances of pharmacological compensation and/or correction of GABAergic and glutamatergic receptors, GABA/glutamate transporters, and GABA/glutamate-associated proteins, with Tor 2 and XL-765 showing optimal outcomes. Our studies lay the groundwork for further evaluation of mTOR inhibitors in aldh5a1 -/- mice, with therapeutic ramifications for heritable disorders of GABA and glutamate neurotransmission.
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Affiliation(s)
- Kara R Vogel
- Division of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Pharmaceutical and Basic Sciences Building Room 347, 412 E. Spokane Falls Blvd, Spokane, WA, 99202, USA.
| | - Garrett R Ainslie
- Division of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Pharmaceutical and Basic Sciences Building Room 347, 412 E. Spokane Falls Blvd, Spokane, WA, 99202, USA
| | - K Michael Gibson
- Division of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Pharmaceutical and Basic Sciences Building Room 347, 412 E. Spokane Falls Blvd, Spokane, WA, 99202, USA
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18
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Malaspina P, Roullet JB, Pearl PL, Ainslie GR, Vogel KR, Gibson KM. Succinic semialdehyde dehydrogenase deficiency (SSADHD): Pathophysiological complexity and multifactorial trait associations in a rare monogenic disorder of GABA metabolism. Neurochem Int 2016; 99:72-84. [PMID: 27311541 DOI: 10.1016/j.neuint.2016.06.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 06/09/2016] [Accepted: 06/10/2016] [Indexed: 12/21/2022]
Abstract
Discovered some 35 years ago, succinic semialdehyde dehydrogenase deficiency (SSADHD) represents a rare, autosomal recessively-inherited defect in the second step of the GABA degradative pathway. Some 200 patients have been reported, with broad phenotypic and genotypic heterogeneity. SSADHD represents an unusual neurometabolic disorder in which two neuromodulatory agents, GABA (and the GABA analogue, 4-hydroxybutyrate), accumulate to supraphysiological levels. The unexpected occurrence of epilepsy in several patients is counterintuitive in view of the hyperGABAergic state, in which sedation might be expected. However, the epileptic status of some patients is most likely represented by broader imbalances of GABAergic and glutamatergic neurotransmission. Cumulative research encompassing decades of basic and clinical study of SSADHD reveal a monogenic disease with broad pathophysiological and clinical phenotypes. Numerous metabolic perturbations unmasked in SSADHD include alterations in oxidative stress parameters, dysregulation of autophagy and mitophagy, dysregulation of both inhibitory and excitatory neurotransmitters and gene expression, and unique subsets of SNP alterations of the SSADH gene (so-called ALDH5A1, or aldehyde dehydrogenase 5A1 gene) on the 6p22 chromosomal arm. While seemingly difficult to collate and interpret, these anomalies have continued to open novel pathways for pharmacotherapeutic considerations. Here, we present an update on selected aspects of SSADHD, the ALDH5A1 gene, and future avenues for research on this rare disorder of GABA metabolism.
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Affiliation(s)
- P Malaspina
- Department of Biology, University "Tor Vergata", Rome, Italy
| | - J-B Roullet
- Division of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Spokane, WA, USA
| | - P L Pearl
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - G R Ainslie
- Division of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Spokane, WA, USA
| | - K R Vogel
- Division of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Spokane, WA, USA
| | - K M Gibson
- Division of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Spokane, WA, USA.
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19
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Bejarano E, Rodríguez-Navarro JA. Autophagy and amino acid metabolism in the brain: implications for epilepsy. Amino Acids 2014; 47:2113-26. [DOI: 10.1007/s00726-014-1822-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 07/31/2014] [Indexed: 12/31/2022]
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20
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Püttmann L, Stehr H, Garshasbi M, Hu H, Kahrizi K, Lipkowitz B, Jamali P, Tzschach A, Najmabadi H, Ropers HH, Musante L, Kuss AW. A novelALDH5A1mutation is associated with succinic semialdehyde dehydrogenase deficiency and severe intellectual disability in an Iranian family. Am J Med Genet A 2013; 161A:1915-22. [DOI: 10.1002/ajmg.a.36030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 04/15/2013] [Indexed: 01/20/2023]
Affiliation(s)
| | - Henning Stehr
- Department of Vertebrate Genomics; Max Planck Institute for Molecular Genetics; Berlin; Germany
| | - Masoud Garshasbi
- Department of Human Molecular Genetics; Max Planck Institute for Molecular Genetics; Berlin; Germany
| | - Hao Hu
- Department of Human Molecular Genetics; Max Planck Institute for Molecular Genetics; Berlin; Germany
| | - Kimia Kahrizi
- Genetics Research Center; University of Social Welfare and Rehabilitation Sciences; Tehran; Iran
| | - Bettina Lipkowitz
- Department of Human Molecular Genetics; Max Planck Institute for Molecular Genetics; Berlin; Germany
| | | | - Andreas Tzschach
- Department of Human Molecular Genetics; Max Planck Institute for Molecular Genetics; Berlin; Germany
| | - Hossein Najmabadi
- Genetics Research Center; University of Social Welfare and Rehabilitation Sciences; Tehran; Iran
| | - Hans-Hilger Ropers
- Department of Human Molecular Genetics; Max Planck Institute for Molecular Genetics; Berlin; Germany
| | - Luciana Musante
- Department of Human Molecular Genetics; Max Planck Institute for Molecular Genetics; Berlin; Germany
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Vogel KR, Pearl PL, Theodore WH, McCarter RC, Jakobs C, Gibson KM. Thirty years beyond discovery--clinical trials in succinic semialdehyde dehydrogenase deficiency, a disorder of GABA metabolism. J Inherit Metab Dis 2013; 36:401-10. [PMID: 22739941 PMCID: PMC4349389 DOI: 10.1007/s10545-012-9499-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 05/09/2012] [Accepted: 05/14/2012] [Indexed: 10/28/2022]
Abstract
This review summarizes a presentation made at the retirement Symposium of Prof. Dr. Cornelis Jakobs in November of 2011, highlighting the progress toward clinical trials in succinic semialdehyde dehydrogenase (SSADH) deficiency, a disorder first recognized in 1981. Active and potential clinical interventions, including vigabatrin, L-cycloserine, the GHB receptor antagonist NCS-382, and the ketogenic diet, are discussed. Several biomarkers to gauge clinical efficacy have been identified, including cerebrospinal fluid metabolites, neuropsychiatric testing, MRI, EEG, and measures of GABAergic function including (11 C)flumazenil positron emission tomography (PET) and transcranial magnetic stimulation (TMS). Thirty years after its discovery, encompassing extensive studies in both patients and the corresponding murine model, we are now running an open-label trial of taurine intervention, and are poised to undertake a phase II trial of the GABAB receptor antagonist SGS742.
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Affiliation(s)
- Kara R Vogel
- Section of Clinical Pharmacology, College of Pharmacy, Washington State University, Spokane, WA 99202-2131, USA.
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Rowley NM, Madsen KK, Schousboe A, Steve White H. Glutamate and GABA synthesis, release, transport and metabolism as targets for seizure control. Neurochem Int 2012; 61:546-58. [PMID: 22365921 DOI: 10.1016/j.neuint.2012.02.013] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 02/09/2012] [Indexed: 11/17/2022]
Abstract
The synthesis, release, reuptake, and metabolism of the excitatory and inhibitory neurotransmitters glutamate and GABA, respectively, are tightly controlled. Given the role that these two neurotransmitters play in normal and abnormal neurotransmission, it is important to consider the processes whereby they are regulated. This brief review is focused entirely on the metabolic aspects of glutamate and GABA synthesis and neurotransmission. It describes in limited detail the synthesis, release, reuptake, metabolism, cellular compartmentation and pharmacology of the glutamatergic and GABAergic synapse. This review also provides a summary and brief description of the pathologic and phenotypic features of the various genetic animal models that have been developed in an effort to provide a greater understanding of the role that each of the aforementioned metabolic processes plays in controlling excitatory and inhibitory neurotransmission and how their use will hopefully facilitate the development of safer and more efficacious therapies for the treatment of epilepsy and other neurological disorders.
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Affiliation(s)
- Nicole M Rowley
- Department of Pharmacology and Toxicology, Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Suite 3211, Salt Lake City, UT 84108, USA
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Pearl PL, Shukla L, Theodore WH, Jakobs C, Gibson KM. Epilepsy in succinic semialdehyde dehydrogenase deficiency, a disorder of GABA metabolism. Brain Dev 2011; 33:796-805. [PMID: 21664777 PMCID: PMC4385391 DOI: 10.1016/j.braindev.2011.04.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 04/27/2011] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Succinic semialdehyde dehydrogenase (SSADH) deficiency is a gamma-aminobutyric acid (GABA) degradative defect. Epilepsy affects half of patients. The murine model is associated with a transition from absence to convulsive seizures in the third week, with fatal status epilepticus. METHODS The clinical phenotype is reported from a patient database. Flumazenil-Positron Emission Topography (FMZ-PET) and Transcranial Magnetic Stimulation (TMS) were used to study GABA neurotransmission. Electrocorticography, single cell electrophysiology, and radioligand binding studies are reported from animal studies. RESULTS Generalized seizures predominate, including tonic-clonic, atypical absence, and myoclonic. EEG discharges are typically generalized spike-wave. MRI shows a dentatopallidoluysian pattern. Sudden Unexpected Death in Epilepsy Patients (SUDEP) has occurred and the associated neuropathology reveals chronic excitotoxic injury in gloubus pallidus. Investigations using FMZ-PET and TMS support downregulation of GABA(A) and GABA(B) activity, respectively, in patients. Gamma-hydroxybutyrate (GHB) induces spike-wave discharges in homozygous null mice via GHB and GABA(B)-mediated mechanisms. These resemble absence seizures and are abolished by a GABA(B) receptor antagonist. Decreased binding of GABA(A) and GABA(B) receptor antagonists has been demonstrated in P19 and P14 null mice, respectively. Downregulation of GABA(A) and GABA(B) receptor subunits is observed by P14. GABA(A) and GABA(B) mediated potentials are reduced from P8-P14. CONCLUSION Generalized epilepsy and epileptiform discharges are characteristic of SSADH deficiency. Spontaneous absence seizures appear in null mice by the third week, which may be induced by GHB or GABA(B) activity. Subsequent overuse dependent downregulation of GABA(A) and GABA(B) receptor activity may be associated with hyperexcitability concomitant with the transition to generalized seizures.
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Affiliation(s)
- Phillip L. Pearl
- Department of Neurology, Children’s National Medical Center, George Washington University School of Medicine, Washington, D.C., USA,Clinical Epilepsy Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Lovy Shukla
- Department of Neurology, Children’s National Medical Center, George Washington University School of Medicine, Washington, D.C., USA
| | - William H. Theodore
- Clinical Epilepsy Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Cornelis Jakobs
- Metabolic Unit, Department of Clinical Chemistry, Vrije University Medical Center, Amsterdam, The Netherlands
| | - K. Michael Gibson
- Department of Biological Sciences, Michigan Technological University, Houghton, MI, USA
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Augmentation of Tonic GABA(A) Inhibition in Absence Epilepsy: Therapeutic Value of Inverse Agonists at Extrasynaptic GABA(A) Receptors. Adv Pharmacol Sci 2011; 2011:790590. [PMID: 21912539 PMCID: PMC3168769 DOI: 10.1155/2011/790590] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 05/16/2011] [Indexed: 12/28/2022] Open
Abstract
It is well established that impaired GABAergic inhibition within neuronal networks can lead to hypersynchronous firing patterns that are the typical cellular hallmark of convulsive epileptic seizures. However, recent findings have highlighted that a pathological enhancement of GABAergic signalling within thalamocortical circuits is a necessary and sufficient condition for nonconvulsive typical absence seizure genesis. In particular, increased activation of extrasynaptic GABAA receptors (eGABAAR) and augmented “tonic” GABAA inhibition in thalamocortical neurons have been demonstrated across a range of genetic and pharmacological models of absence epilepsy. Moreover, evidence from monogenic mouse models (stargazer/lethargic) and the polygenic Genetic Absence Epilepsy Rats from Strasbourg (GAERS) indicate that the mechanism underlying eGABAAR gain of function is nonneuronal in nature and results from a deficiency in astrocytic GABA uptake through the GAT-1 transporter. These results challenge the existing theory that typical absence seizures are underpinned by a widespread loss of GABAergic function in thalamocortical circuits and illustrate a vital role for astrocytes in the pathology of typical absence epilepsy. Moreover, they explain why pharmacological agents that enhance GABA receptor function can initiate or exacerbate absence seizures and suggest a potential therapeutic role for inverse agonists at eGABAARs in absence epilepsy.
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Kim KJ, Pearl PL, Jensen K, Snead OC, Malaspina P, Jakobs C, Gibson KM. Succinic semialdehyde dehydrogenase: biochemical-molecular-clinical disease mechanisms, redox regulation, and functional significance. Antioxid Redox Signal 2011; 15:691-718. [PMID: 20973619 PMCID: PMC3125545 DOI: 10.1089/ars.2010.3470] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Succinic semialdehyde dehydrogenase (SSADH; aldehyde dehydrogenase 5a1, ALDH5A1; E.C. 1.2.1.24; OMIM 610045, 271980) deficiency is a rare heritable disorder that disrupts the metabolism of the inhibitory neurotransmitter 4-aminobutyric acid (GABA). Identified in conjunction with increased urinary excretion of the GABA analog gamma-hydroxybutyric acid (GHB), numerous patients have been identified worldwide and the autosomal-recessive disorder has been modeled in mice. The phenotype is one of nonprogressive neurological dysfunction in which seizures may be prominently displayed. The murine model is a reasonable phenocopy of the human disorder, yet the severity of the seizure disorder in the mouse exceeds that observed in SSADH-deficient patients. Abnormalities in GABAergic and GHBergic neurotransmission, documented in patients and mice, form a component of disease pathophysiology, although numerous other disturbances (metabolite accumulations, myelin abnormalities, oxidant stress, neurosteroid depletion, altered bioenergetics, etc.) are also likely to be involved in developing the disease phenotype. Most recently, the demonstration of a redox control system in the SSADH protein active site has provided new insights into the regulation of SSADH by the cellular oxidation/reduction potential. The current review summarizes some 30 years of research on this protein and disease, addressing pathological mechanisms in human and mouse at the protein, metabolic, molecular, and whole-animal level.
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Affiliation(s)
- Kyung-Jin Kim
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Phillip L. Pearl
- Department of Neurology, Children's National Medical Center, Washington, District of Columbia
| | - Kimmo Jensen
- Synaptic Physiology Laboratory, Department of Physiology and Biophysics, Aarhus University, Aarhus, Denmark
- Center for Psychiatric Research, Aarhus University Hospital, Risskov, Denmark
| | - O. Carter Snead
- Department of Neurology, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | | | - Cornelis Jakobs
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands
| | - K. Michael Gibson
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan
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Errington AC, Gibson KM, Crunelli V, Cope DW. Aberrant GABA(A) receptor-mediated inhibition in cortico-thalamic networks of succinic semialdehyde dehydrogenase deficient mice. PLoS One 2011; 6:e19021. [PMID: 21526163 PMCID: PMC3079762 DOI: 10.1371/journal.pone.0019021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 03/14/2011] [Indexed: 01/19/2023] Open
Abstract
Aberrant γ-aminobutyric acid type A (GABAA) receptor-mediated inhibition in cortico-thalamic networks remains an attractive mechanism for typical absence seizure genesis. Using the whole-cell patch clamp technique we examined ‘phasic’ and ‘tonic’ GABAA inhibition in thalamocortical neurons of somatosensory (ventrobasal, VB) thalamus, nucleus reticularis thalami (NRT) neurons, and layer 5/6 pyramidal neurons of the somatosensory (barrel) cortex of succinic semialdehyde dehydrogenase (SSADH) knock-out (SSADH−/−) mice that replicate human SSADH deficiency and exhibit typical absence seizures. We found increased sIPSC frequency in both VB and NRT neurons and larger sIPSC amplitude in VB neurons of SSADH−/− mice compared to wild-type animals, demonstrating an increase in total phasic inhibition in thalamus of SSADH−/− mice. mIPSCs in both VB and NRT neurons were no different between genotypes, although there remained a trend toward more events in SSADH−/− mice. In cortical layer 5/6 pyramidal neurons, sIPSCs were fewer but larger in SSADH−/− mice, a feature retained by mIPSCs. Tonic currents were larger in both thalamocortical neurons and layer 5/6 pyramidal neurons from SSADH−/− mice compared to WTs. These data show that enhanced, rather than compromised, GABAA receptor-mediated inhibition occurs in cortico-thalamic networks of SSADH−/− mice. In agreement with previous studies, GABAA receptor-mediated inhibitory gain-of-function may be a common feature in models of typical absence seizures, and could be of pathological importance in patients with SSADH deficiency.
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Affiliation(s)
- Adam C Errington
- School of Biosciences, Cardiff University, Cardiff, United Kingdom.
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Acosta MT, Munasinghe J, Pearl PL, Gupta M, Finegersh A, Gibson KM, Theodore WH. Cerebellar atrophy in human and murine succinic semialdehyde dehydrogenase deficiency. J Child Neurol 2010; 25:1457-61. [PMID: 20445195 PMCID: PMC3155424 DOI: 10.1177/0883073810368137] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Human succinic semialdehyde dehydrogenase deficiency, an autosomal recessive disorder of γ-aminobutyric acid (GABA) catabolism, was modeled by a murine model sharing the phenotype of ataxia and seizures. Magnetic resonance imaging (MRI) with volumetry was obtained on 7 patients versus controls, and MRI with stereology was derived in 3 murine genotypes: null, wild-type, and heterozygous mutants. All patients had T1 hypointensity and T2 hyperintensity in globus pallidus, and 5 also had similar changes in subthalamic and cerebellar dentate nuclei. There was a trend for patients to have a smaller cerebellar vermis. Homozygous null mice had significantly lower total brain and cerebellar volumes than wild-types and heterozygotes. Stereology confirmed cerebellar atrophy and was otherwise normal in multiple regions. Cerebellar volume loss is present in the murine disorder with a trend for cerebellar atrophy in patients. Reduced cerebellar volume can reflect neurodegeneration and may be related to the clinical manifestations.
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Affiliation(s)
- Maria T. Acosta
- Clinical Epilepsy Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, Department of Neurology, Children's National Medical Center, Washington, DC
| | - Jeeva Munasinghe
- Mouse Imaging Facility, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Phillip L. Pearl
- Clinical Epilepsy Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, Department of Neurology, Children's National Medical Center, Washington, DC
| | - Maneesh Gupta
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon
| | - Andrey Finegersh
- Clinical Epilepsy Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland
| | - K. Michael Gibson
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan
| | - William H. Theodore
- Clinical Epilepsy Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland
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28
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Dósa Z, Nieto-Gonzalez JL, Korshoej AR, Gibson KM, Jensen K. Effect of gene dosage on single-cell hippocampal electrophysiology in a murine model of SSADH deficiency (gamma-hydroxybutyric aciduria). Epilepsy Res 2010; 90:39-46. [PMID: 20363598 DOI: 10.1016/j.eplepsyres.2010.03.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 03/02/2010] [Accepted: 03/07/2010] [Indexed: 12/20/2022]
Abstract
Human and murine succinic semialdehyde dehydrogenase (SSADH; gamma-hydroxybutyric (GHB) aciduria) deficiency represents an epileptic disorder associated with hyperGABA- and hyperGHB-ergic states. Despite significant neurotransmitters alterations, well-defined single-cell electrophysiological studies, aimed to provide insight into regional neuropathology, have been lacking. In this study, we characterized the effect of residual SSADH enzyme function/increased GABA levels on single-cell hippocampal electrophysiology in SSADH+/+ (wild-type; WT), SSADH+/- (heterozygous; HET), and SSADH-/- (knock-out; KO) mice. Tonic extrasynaptic GABAA receptor (GABAAR)-mediated currents were elevated in HET and KO mice, whereas phasic synaptic GABAAR currents were unaltered in dentate gyrus granule cells. Similarly, tonic GABAAR-mediated currents were increased in dentate gyrus interneurons of KO animals, while phasic GABAergic neurotransmission was unaffected in the same cells. Our results indicate global disruption of cortical networks in SSADH KO mice, affecting both excitatory and inhibitory neurons. Our findings provide new clues concerning seizure evolution in the murine model (absence-->tonic-clonic-->status epilepticus), and extend pathophysiological insight into human SSADH deficiency.
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Affiliation(s)
- Zita Dósa
- Synaptic Physiology Laboratory, Department of Physiology and Biophysics, Aarhus University, Aarhus, Denmark
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29
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Pearl PL, Gibson KM, Quezado Z, Dustin I, Taylor J, Trzcinski S, Schreiber J, Forester K, Reeves-Tyer P, Liew C, Shamim S, Herscovitch P, Carson R, Butman J, Jakobs C, Theodore W. Decreased GABA-A binding on FMZ-PET in succinic semialdehyde dehydrogenase deficiency. Neurology 2009; 73:423-9. [PMID: 19667317 DOI: 10.1212/wnl.0b013e3181b163a5] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Succinic semialdehyde dehydrogenase (SSADH) deficiency is an autosomal recessive disorder of GABA metabolism characterized by elevated levels of GABA and gamma-hydroxybutyric acid. Clinical findings include intellectual impairment, hypotonia, hyporeflexia, hallucinations, autistic behaviors, and seizures. Autoradiographic labeling and slice electrophysiology studies in the murine model demonstrate use-dependent downregulation of GABA(A) receptors. We studied GABA(A) receptor activity in human SSADH deficiency utilizing [(11)C]-flumazenil (FMZ)-PET. METHODS FMZ binding was measured in 7 patients, 10 unaffected parents, and 8 healthy controls. Data analysis was performed using a reference region compartmental model, with time-activity curve from pons as the input function. Relative parametric binding potential (BP(ND)) was derived, with MRI-based pixel by pixel partial volume correction, in regions of interest drawn on coregistered MRI. RESULTS In amygdala, hippocampus, cerebellar vermis, frontal, parietal, and occipital cortex, patients with SSADH deficiency had significant reductions in FMZ BP(ND) compared to parents and controls. Mean cortical values were 6.96 +/- 0.79 (controls), 6.89 +/- 0.71 (parents), and 4.88 +/- 0.77 (patients) (F ratio 16.1; p < 0.001). There were no differences between controls and parents in any cortical region. CONCLUSIONS Succinic semialdehyde dehydrogenase (SSADH) deficient patients show widespread reduction in BZPR binding on [(11)C]-flumazenil-PET. Our results suggest that high endogenous brain GABA levels in SSADH deficiency downregulate GABA(A)-BZPR binding site availability. This finding suggests a potential mechanism for neurologic dysfunction in a serious neurodevelopmental disorder, and suggests that PET may be useful to translate studies in animal models to human disease.
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Affiliation(s)
- P L Pearl
- Department of Neurology, Children's National Medical Center, Washington, DC 20010-2970, USA.
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30
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Pearl PL, Gibson KM, Cortez MA, Wu Y, Carter Snead O, Knerr I, Forester K, Pettiford JM, Jakobs C, Theodore WH. Succinic semialdehyde dehydrogenase deficiency: lessons from mice and men. J Inherit Metab Dis 2009; 32:343-52. [PMID: 19172412 PMCID: PMC2693236 DOI: 10.1007/s10545-009-1034-y] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/14/2008] [Accepted: 11/26/2008] [Indexed: 12/23/2022]
Abstract
Succinic semialdehyde dehydrogenase (SSADH) deficiency, a disorder of GABA degradation with subsequent elevations in brain GABA and GHB, is a neurometabolic disorder with intellectual disability, epilepsy, hypotonia, ataxia, sleep disorders, and psychiatric disturbances. Neuroimaging reveals increased T2-weighted MRI signal usually affecting the globus pallidus, cerebellar dentate nucleus, and subthalamic nucleus, and often cerebral and cerebellar atrophy. EEG abnormalities are usually generalized spike-wave, consistent with a predilection for generalized epilepsy. The murine phenotype is characterized by failure-to-thrive, progressive ataxia, and a transition from generalized absence to tonic-clonic to ultimately fatal convulsive status epilepticus. Binding and electrophysiological studies demonstrate use-dependent downregulation of GABA(A) and (B) receptors in the mutant mouse. Translational human studies similarly reveal downregulation of GABAergic activity in patients, utilizing flumazenil-PET and transcranial magnetic stimulation for GABA(A) and (B) activity, respectively. Sleep studies reveal decreased stage REM with prolonged REM latencies and diminished percentage of stage REM. An ad libitum ketogenic diet was reported as effective in the mouse model, with unclear applicability to the human condition. Acute application of SGS-742, a GABA(B) antagonist, leads to improvement in epileptiform activity on electrocorticography. Promising mouse data using compounds available for clinical use, including taurine and SGS-742, form the framework for human trials.
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MESH Headings
- Animals
- Brain Diseases, Metabolic, Inborn/diagnosis
- Brain Diseases, Metabolic, Inborn/etiology
- Brain Diseases, Metabolic, Inborn/genetics
- Brain Diseases, Metabolic, Inborn/therapy
- Disease Models, Animal
- Humans
- Mice
- Mice, Transgenic
- Models, Biological
- Succinate-Semialdehyde Dehydrogenase/deficiency
- Succinate-Semialdehyde Dehydrogenase/genetics
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Affiliation(s)
- P L Pearl
- Department of Neurology, Children's National Medical Center, George Washington University School of Medicine, 111 Michigan Avenue, NW, Washington, DC 20010-2970, USA.
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Drasbek KR, Vardya I, Delenclos M, Gibson KM, Jensen K. SSADH deficiency leads to elevated extracellular GABA levels and increased GABAergic neurotransmission in the mouse cerebral cortex. J Inherit Metab Dis 2008; 31:662-8. [PMID: 18696252 PMCID: PMC2596865 DOI: 10.1007/s10545-008-0941-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 07/03/2008] [Accepted: 07/11/2008] [Indexed: 12/01/2022]
Abstract
Succinic semialdehyde dehydrogenase (SSADH) deficiency is an inherited disorder in which patients display neurodevelopmental retardation, ataxia, and epileptic seizures. The recently engineered SSADH knock-out (KO) mouse models the severe form of the human disorder. The SSADH enzyme participates in the breakdown of the inhibitory neurotransmitter GABA, and studies have shown increases in brain GABA and downregulation of GABA(A) receptor beta(2) subunits in the cerebral cortex of these mice. Here, we used brain slice electrophysiology to investigate the alterations in GABA neurotransmission in SSADH KO mouse cortex. In layer 2/3 pyramidal cells, spontaneous inhibitory postsynaptic currents (IPSCs), reflecting activity of GABAergic synaptic contacts, were normal in SSADH KO mice. Also, IPSCs evoked by electrical single-axon stimulation in KO mice were normal. In contrast, tonic inhibition mediated by presumed extrasynaptic GABA(A) receptors was strongly increased, indicating significantly raised extracellular GABA levels. The excessive cortical GABAergic neurotransmission may participate in the seizure activity in SSADH deficiency.
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Affiliation(s)
- K R Drasbek
- Synaptic Physiology Laboratory, Institute of Physiology and Biophysics, University of Aarhus, Aarhus, Denmark
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32
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Neurotransmitter alterations in embryonic succinate semialdehyde dehydrogenase (SSADH) deficiency suggest a heightened excitatory state during development. BMC DEVELOPMENTAL BIOLOGY 2008; 8:112. [PMID: 19040727 PMCID: PMC2642797 DOI: 10.1186/1471-213x-8-112] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Accepted: 11/28/2008] [Indexed: 11/10/2022]
Abstract
BACKGROUND SSADH (aldehyde dehydrogenase 5a1 (Aldh5a1); gamma-hydroxybutyric (GHB) aciduria) deficiency is a defect of GABA degradation in which the neuromodulators GABA and GHB accumulate. The human phenotype is that of nonprogressive encephalopathy with prominent bilateral discoloration of the globi pallidi and variable seizures, the latter displayed prominently in Aldh5a1-/- mice with lethal convulsions. Metabolic studies in murine neural tissue have revealed elevated GABA [and its derivatives succinate semialdehyde (SSA), homocarnosine (HC), 4,5-dihydroxyhexanoic acid (DHHA) and guanidinobutyrate (GB)] and GHB [and its analogue D-2-hydroxyglutarate (D-2-HG)] at birth. Because of early onset seizures and the neurostructural anomalies observed in patients, we examined metabolite features during Aldh5a1-/- embryo development. METHODS Embryos were obtained from pregnant dams sacrificed at E (embryo day of life) 10-13, 14-15, 16-17, 18-19 and newborn mice. Intact embryos were extracted and metabolites quantified by isotope dilution mass spectrometry (n = 5-15 subjects, Aldh5a1+/+ and Aldh5a1-/-) for each gestational age group. Data was evaluated using the t test and one-way ANOVA with Tukey post hoc analysis. Significance was set at the 95th centile. RESULTS GABA and DHHA were significantly elevated at all gestational ages in Aldh5a1-/- mice, while GB was increased only late in gestation; SSA was not elevated at any time point. GHB and D-2-HG increased in an approximately linear fashion with gestational age. Correlative studies in human amniotic fluid from SSADH-deficient pregnancies (n = 5) also revealed significantly increased GABA. CONCLUSION Our findings indicate early GABAergic alterations in Aldh5a1-/- mice, possibly exacerbated by other metabolites, which likely induce a heightened excitatory state that may predispose neural networks to epilepsy in these animals.
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Stewart LS, Nylen KJ, Persinger MA, Cortez MA, Gibson KM, Snead OC. Circadian distribution of generalized tonic-clonic seizures associated with murine succinic semialdehyde dehydrogenase deficiency, a disorder of GABA metabolism. Epilepsy Behav 2008; 13:290-4. [PMID: 18514581 PMCID: PMC2574901 DOI: 10.1016/j.yebeh.2008.04.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 04/17/2008] [Accepted: 04/18/2008] [Indexed: 11/29/2022]
Abstract
Human succinic semialdehyde dehydrogenase (SSADH) deficiency is an autosomal recessive disorder of GABA metabolism associated with motor impairment and epileptic seizures. Similarly, mice with targeted deletion of the Aldh5a1 gene (Aldh5a1(-/-)) exhibit SSADH deficiency and seizures early in life. These seizures begin as absence seizures the second week of life, but evolve into generalized convulsive seizures that increase in severity and become lethal during the fourth postnatal week. The seizures are alleviated and survival is prolonged when the mutant animals are weaned onto a ketogenic diet (KD). The persistence of spontaneous, recurrent, generalized tonic-clonic seizures in KD-treated adult Aldh5a1(-/-) mice allowed us to quantify their daily (circadian) distribution using a novel behavioral method based on the detection of changes in movement velocity. Adult KD-treated Aldh5a1(-/-) mice exhibited a seizure phenotype characterized by fits of wild running clonus accompanied by jumping and bouncing. These hypermotor seizures were largely spontaneous and occurred daily in a nonrandom pattern. The seizure rhythm showed a peak shortly after dark phase onset (2008 hours) with near-24-hour periodicity. Age-matched wild-type littermates showed no evidence of abnormal motor behavior. These new data suggest that generalized tonic-clonic seizures in Aldh5a1(-/-) mice are more frequent during a specific time of day and will provide useful information to clinicians for the treatment of seizures associated with human SSADH deficiency.
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Affiliation(s)
- Lee S. Stewart
- Neurosciences and Mental Health Research Program, The Hospital for Sick Children, 555 University Avenue, Toronto ON, Canada M5G 1X8
| | - Kirk J. Nylen
- Neurosciences and Mental Health Research Program, The Hospital for Sick Children, 555 University Avenue, Toronto ON, Canada M5G 1X8
| | - Michael A. Persinger
- Behavioral Neuroscience Program, Department of Psychology, Laurentian University, Sudbury ON, Canada P3E 2C6
| | - Miguel A. Cortez
- Neurosciences and Mental Health Research Program, The Hospital for Sick Children, 555 University Avenue, Toronto ON, Canada M5G 1X8, Division of Neurology, The Hospital for Sick Children, 555 University Avenue, Toronto ON, Canada M5G 1X8, Department of Pediatrics, Faculty of Medicine, University of Toronto, 190 Elizabeth Street, Toronto ON, Canada M5G 2C4
| | - K. Michael Gibson
- Division of Medical Genetics, Departments of Pediatrics and Pathology, University of Pittsburgh School of Medicine, Rangos Research Center, 3460 Fifth Avenue, Pittsburgh PA 15213, USA
| | - O. Carter Snead
- Neurosciences and Mental Health Research Program, The Hospital for Sick Children, 555 University Avenue, Toronto ON, Canada M5G 1X8, Division of Neurology, The Hospital for Sick Children, 555 University Avenue, Toronto ON, Canada M5G 1X8, Department of Pediatrics, Faculty of Medicine, University of Toronto, 190 Elizabeth Street, Toronto ON, Canada M5G 2C4, Corresponding author. Address: Neurosciences and Mental Health Research Program, The Hospital for Sick Children, 555 University Avenue, Toronto ON, Canada M5G 1X8. Fax: +1 416 813 6334. E-mail address: (O.C. Snead, III)
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Neuropsychiatric morbidity in adolescent and adult succinic semialdehyde dehydrogenase deficiency patients. CNS Spectr 2008; 13:598-605. [PMID: 18622364 PMCID: PMC2562649 DOI: 10.1017/s1092852900016874] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Succinic semialdehyde dehydrogenase (SSADH) deficiency (gamma-hydroxybutyric aciduria) is a rare neurometabolic disorder of gamma-aminobutyric acid degradation. While neurological manifestations, such as developmental delay, are typical during infancy, limited data are available on adolescent and adult symptomatology. METHODS We overview the phenotype of 33 adolescents and adults (10.1-39.5 years of age, mean: 17.1 years, 48% females) with SSADH deficiency. For this purpose, we applied a database with systematic questionnaire-based follow-up data. RESULTS Sixty-six percent of patients (n=21) presented by 6 months of age, 14% from 6-12 months of age, 5% from 1-2 years of age, and 14% from 2-4 years of age, mean age at first symptoms was 11+/-12 months. However, mean age at diagnosis was 6.6+/-6.4 years of age. Presenting symptoms encompassed motor delay, hypotonia, speech delay, autistic features, seizures, and ataxia. Eighty-two percent demonstrated behavioral problems, such as attention deficit, hyperactivity, anxiety, or aggression, and 33% had >or=3 behavior problems. Electroencephalograms showed background slowing or epileptiform discharges in 40% of patients. Treatment approaches are then summarized. CONCLUSION The variable phenotype in SSADH deficiency suggests the likelihood that this disease may be under-diagnosed. Families of patients with SSADH deficiency should be counseled and supported regarding the anticipated persistence of various neuropsychiatric symptoms into adulthood.
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Latini A, Scussiato K, Leipnitz G, Gibson KM, Wajner M. Evidence for oxidative stress in tissues derived from succinate semialdehyde dehydrogenase-deficient mice. J Inherit Metab Dis 2007; 30:800-10. [PMID: 17885820 DOI: 10.1007/s10545-007-0599-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 04/19/2007] [Accepted: 06/08/2007] [Indexed: 02/06/2023]
Abstract
Animal models of inborn errors of metabolism are useful for investigating the pathogenesis associated with the corresponding human disease. Since the mechanisms involved in the pathophysiology of succinate semialdehyde dehydrogenase (SSADH) deficiency (Aldh5a1; OMIM 271980) are still not established, in the present study we evaluated the tissue antioxidant defences and lipid peroxidation in various cerebral structures (cortex, cerebellum, thalamus and hippocampus) and in the liver of SSADH-deficient mice. The parameters analysed were total radical-trapping antioxidant potential (TRAP) and glutathione (GSH) levels, the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as thiobarbituric acid-reactive substances (TBARS). We first observed that the tissue nonenzymatic antioxidant defences were significantly reduced in the SSADH-deficient animals, particularly in the liver (decreased TRAP and GSH) and in the cerebral cortex (decreased GSH), as compared to the wild-type mice. Furthermore, SOD activity was significantly increased in the liver and cerebellum, whereas the activity of CAT was significantly higher in the thalamus. In contrast, GPx activity was significantly diminished in the hippocampus. Finally, we observed that lipid peroxidation (TBARS levels) was markedly increased in the liver and cerebral cortex, reflecting a high lipid oxidative damage in these tissues. Our data showing an imbalance between tissue antioxidant defences and oxidative attack strongly indicate that oxidative stress is involved in the pathophysiology of SSADH deficiency in mice, and likely the corresponding human disorder.
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Affiliation(s)
- A Latini
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
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Chowdhury GMI, Gupta M, Gibson KM, Patel AB, Behar KL. Altered cerebral glucose and acetate metabolism in succinic semialdehyde dehydrogenase-deficient mice: evidence for glial dysfunction and reduced glutamate/glutamine cycling. J Neurochem 2007; 103:2077-91. [PMID: 17854388 DOI: 10.1111/j.1471-4159.2007.04887.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Succinic semialdehyde dehydrogenase (SSADH) catalyzes the NADP-dependent oxidation of succinic semialdehyde to succinate, the final step of the GABA shunt pathway. SSADH deficiency in humans is associated with excessive elevation of GABA and gamma-hydroxybutyrate (GHB). Recent studies of SSADH-null mice show that elevated GABA and GHB are accompanied by reduced glutamine, a known precursor of the neurotransmitters glutamate and GABA. In this study, cerebral metabolism was investigated in urethane-anesthetized SSADH-null and wild-type 17-day-old mice by intraperitoneal infusion of [1,6-(13)C(2)]glucose or [2-(13)C]acetate for different periods. Cortical extracts were prepared and measured using high-resolution (1)H-[(13)C] NMR spectroscopy. Compared with wild-type, levels of GABA, GHB, aspartate, and alanine were significantly higher in SSADH-null cortex, whereas glutamate, glutamine, and taurine were lower. (13)C Labeling from [1,6-(13)C(2)]glucose, which is metabolized in neurons and glia, was significantly lower (expressed as mumol of (13)C incorporated per gram of brain tissue) for glutamate-(C4,C3), glutamine-C4, succinate-(C3/2), and aspartate-C3 in SSADH-null cortex, whereas Ala-C3 was higher and GABA-C2 unchanged. (13)C Labeling from [2-(13)C]acetate, a glial substrate, was lower mainly in glutamine-C4 and glutamate-(C4,C3). GHB was labeled by both substrates in SSADH-null mice consistent with GABA as precursor. Our findings indicate that SSADH deficiency is associated with major alterations in glutamate and glutamine metabolism in glia and neurons with surprisingly lesser effects on GABA synthesis.
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Affiliation(s)
- G M I Chowdhury
- Department of Diagnostic Radiology, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA.
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Knerr I, Pearl PL, Bottiglieri T, Snead OC, Jakobs C, Gibson KM. Therapeutic concepts in succinate semialdehyde dehydrogenase (SSADH; ALDH5a1) deficiency (gamma-hydroxybutyric aciduria). Hypotheses evolved from 25 years of patient evaluation, studies in Aldh5a1-/- mice and characterization of gamma-hydroxybutyric acid pharmacology. J Inherit Metab Dis 2007; 30:279-94. [PMID: 17457693 DOI: 10.1007/s10545-007-0574-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 02/02/2007] [Accepted: 02/14/2007] [Indexed: 02/07/2023]
Abstract
We overview the pathophysiological bases, clinical approaches and potential therapeutic options for succinate semialdehyde dehydrogenase (SSADH; EC1.2.1.24) deficiency (gamma-hydroxybutyric aciduria, OMIM 271980, 610045) in relation to studies on SSADH gene-deleted mice, outcome data developed from 25 years of patient evaluation, and characterization of gamma-hydroxybutyric acid (GHB) pharmacology in different species. The clinical picture of this disorder encompasses a wide spectrum of neurological and psychiatric dysfunction, such as psychomotor retardation, delayed speech development, epileptic seizures and behavioural disturbances, emphasizing the multifactorial pathophysiology of SSADH deficiency. The murine SSADH-/- (e.g. Aldh5a1-/-) mouse model suffers from epileptic seizures and succumbs to early lethality. Aldh5a1-/- mice accumulate GHB and gamma-aminobutyric acid (GABA) in the central nervous system, exhibit alterations of amino acids such as glutamine (Gln), alanine (Ala) and arginine (Arg), and manifest disturbances in other systems including dopamine, neurosteroids and antioxidant status. Therapeutic concepts in patients with SSADH deficiency and preclinical therapeutic experiments are discussed in light of data collected from research in Aldh5a1-/- mice and animal studies of GHB pharmacology; these studies are the foundation for novel working approaches, including pharmacological and dietary trials, which are presented for future evaluation in this disease.
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Affiliation(s)
- I Knerr
- Children's and Adolescents' Hospital, University of Erlangen-Nuremberg, Erlangen, Germany
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Barcelo-Coblijn G, Murphy EJ, Mills K, Winchester B, Jakobs C, Snead O, Gibson KM. Lipid abnormalities in succinate semialdehyde dehydrogenase (Aldh5a1-/-) deficient mouse brain provide additional evidence for myelin alterations. Biochim Biophys Acta Mol Basis Dis 2007; 1772:556-62. [PMID: 17300923 PMCID: PMC2362103 DOI: 10.1016/j.bbadis.2006.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 12/20/2006] [Accepted: 12/21/2006] [Indexed: 10/23/2022]
Abstract
Earlier work from our laboratory provided evidence for myelin abnormalities (decreased quantities of proteins associated with myelin compaction, decreased sheath thickness) in cortex and hippocampus of Aldh5a1(-/-) mice, which have a complete ablation of the succinate semialdehyde dehydrogenase protein [E.A. Donarum, D.A. Stephan, K. Larkin, E.J. Murphy, M. Gupta, H. Senephansiri, R.C. Switzer, P.L. Pearl, O.C. Snead, C. Jakobs, K.M. Gibson, Expression profiling reveals multiple myelin alterations in murine succinate semialdehyde dehydrogenase deficiency, J. Inher. Metab. Dis. 29 (2006) 143-156]. In the current report, we have extended these findings via comprehensive analysis of brain phospholipid fractions, including quantitation of fatty acids in individual phospholipid subclasses and estimation of hexose-ceramide in Aldh5a1(-/-) brain. In comparison to wild-type littermates (Aldh5a1(+/+)), we detected a 20% reduction in the ethanolamine glycerophospholipid content of Aldh5a1(-/-)mice, while other brain phospholipids (choline glycerophospholipid, phosphatidylserine and phosphatidylinositol) were within normal limits. Analysis of individual fatty acids in each of these fractions revealed consistent alterations in n-3 fatty acids, primarily increased 22:6n-3 levels (docosahexaenoic acid; DHA). In the phosphatidyl serine fraction there were marked increases in the proportions of polyunsaturated fatty acids with corresponding decreases of monounsaturated fatty acids. Interestingly, the levels of hexose-ceramide (glucosyl- and galactosylceramide, principal myelin cerebrosides) were decreased in Aldh5a1(-/-) brain tissue (one-tailed t test, p=0.0449). The current results suggest that lipid and myelin abnormalities in this animal may contribute to the pathophysiology.
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Affiliation(s)
- G. Barcelo-Coblijn
- Department of Pharmacology, Physiology, and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, USA
| | - E. J. Murphy
- Department of Pharmacology, Physiology, and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, USA
| | - K. Mills
- Biochemistry, Endocrinology & Metabolism Unit, UCL Institute of Child Health at Great Ormond Street Hospital, University College, London, United Kingdom
| | - B. Winchester
- Biochemistry, Endocrinology & Metabolism Unit, UCL Institute of Child Health at Great Ormond Street Hospital, University College, London, United Kingdom
| | - C. Jakobs
- VU University Medical Center, Amsterdam, the Netherlands
| | - O.C. Snead
- Brain and Behavior Program, Division of Neurology and Department of Pediatrics, Faculty of Medicine, Hospital for Sick Children and University of Toronto, Ontario, Canada
| | - KM Gibson
- Division of Medical Genetics, Departments of Pediatrics, Pathology and Human Genetics, Children’s Hospital Pittsburgh and the University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- *Correspondence: Rangos Research Building, Room 2111, Children’s Hospital Pittsburgh, 3460 Fifth Ave., Pittsburgh, PA, 15213; 412-692-7608; fax 412-692-7816;
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Struys EA, Verhoeven NM, Jansen EEW, Ten Brink HJ, Gupta M, Burlingame TG, Quang LS, Maher T, Rinaldo P, Snead OC, Goodwin AK, Weerts EM, Brown PR, Murphy TC, Picklo MJ, Jakobs C, Gibson KM. Metabolism of gamma-hydroxybutyrate to d-2-hydroxyglutarate in mammals: further evidence for d-2-hydroxyglutarate transhydrogenase. Metabolism 2006; 55:353-8. [PMID: 16483879 DOI: 10.1016/j.metabol.2005.09.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2005] [Accepted: 09/19/2005] [Indexed: 11/25/2022]
Abstract
gamma-Hydroxybutyratic acid (GHB), and its prodrugs 4-butyrolactone and 1,4-butanediol, represent expanding drugs of abuse, although GHB is also used therapeutically to treat narcolepsy and alcoholism. Thus, the pathway by which GHB is metabolized is of importance. The goal of the current study was to examine GHB metabolism in mice with targeted ablation of the GABA degradative enzyme succinic semialdehyde dehydrogenase (SSADH(-/-) mice), in whom GHB persistently accumulates, and in baboons intragastrically administered with GHB immediately and persistently. Three hypotheses concerning GHB metabolism were tested: (1) degradation via mitochondrial fatty acid beta-oxidation; (2) conversion to 4,5-dihydroxyhexanoic acid (a putative condensation product of the GHB derivative succinic semialdehyde); and (3) conversion to d-2-hydroxyglutaric acid (d-2-HG) catalyzed by d-2-hydroxyglutarate transhydrogenase (a reaction previously documented only in rat). Both d-2-HG and 4,5-dihydroxyhexanoic acid were significantly increased in neural and nonneural tissue extracts derived from SSADH(-/-) mice. In vitro studies demonstrated the ability of 4,5-dihydroxyhexanoic acid to displace the GHB receptor ligand NCS-382 (IC(50) = 38 micromol/L), although not affecting GABA(B) receptor binding. Blood and urine derived from baboons administered with GHB also accumulated d-2-HG, but not 4,5-dihydroxyhexanoic acid. Our results indicate that d-2-HG is a prominent GHB metabolite and provide further evidence for the existence of d-2-hydroxyglutarate transhydrogenase in different mammalian species.
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Affiliation(s)
- Eduard A Struys
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands
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Jansen EEW, Verhoeven NM, Jakobs C, Schulze A, Senephansiri H, Gupta M, Snead OC, Gibson KM. Increased guanidino species in murine and human succinate semialdehyde dehydrogenase (SSADH) deficiency. Biochim Biophys Acta Mol Basis Dis 2006; 1762:494-8. [PMID: 16504488 DOI: 10.1016/j.bbadis.2006.01.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Revised: 01/18/2006] [Accepted: 01/19/2006] [Indexed: 11/23/2022]
Abstract
Mice with targeted deletion of the GABA-degradative enzyme succinate semialdehyde dehydrogenase (SSADH; Aldh5a1; OMIM 271,980) manifest globally elevated GABA and regionally decreased arginine in brain extracts. We examined the hypothesis that arginine-glycine amidinotransferase catalyzed the formation of guanidinobutyrate (GB) from increased GABA by quantifying guanidinoacetate (GA), guanidinopropionate (GP) and GB in brain extracts employing stable isotope dilution gas chromatographic-mass spectrometry. GA and GB were up to 4- and 22-fold elevated, respectively, in total and regional (cerebellum, hippocampus, cortex) brain extracts derived from SSADH(-/-) mice. Corresponding analyses of urine and cerebrospinal fluid derived from SSADH-deficient patients revealed significant (P<0.05) elevations of GA and GB in urine, as well as GB levels in CSF. These data suggest that GB may be an additional marker of SSADH deficiency, implicate additional pathways of pathophysiology, and identify the second instance of elevated GB in a human inborn error of metabolism.
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Affiliation(s)
- Erwin E W Jansen
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center, Amsterdam, The Netherlands
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Donarum EA, Stephan DA, Larkin K, Murphy EJ, Gupta M, Senephansiri H, Switzer RC, Pearl PL, Snead OC, Jakobs C, Gibson KM. Expression profiling reveals multiple myelin alterations in murine succinate semialdehyde dehydrogenase deficiency. J Inherit Metab Dis 2006; 29:143-56. [PMID: 16601881 DOI: 10.1007/s10545-006-0247-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Accepted: 01/31/2006] [Indexed: 11/30/2022]
Abstract
Succinic semialdehyde dehydrogenase (SSADH) deficiency, a rare genetic defect of GABA degradation recently modelled in mice (SSADH(-/-) mice), manifests early absence seizures that evolve into generalized convulsive seizures and lethal status epilepticus in gene-ablated mice. Disrupted GABA homeostasis, in conjunction with the epileptic phenotype and increased gamma-hydroxybutyric acid (GHB), suggested that expression profiling with the U74Av2 Affymetrix system would reveal dysregulation of receptor genes associated with GABAergic and glutamatergic neurotransmission. Unexpectedly, we found significant downregulation for genes associated with myelin biogenesis and compaction, predominantly in hippocampus and cortex. These results were confirmed by: (1) myelin basic protein (MBP) immunohistochemistry; (2) western blotting of myelin-associated glycoprotein (MAG) and MBP; (3) qRT-PCR analyses of myelin-associated oligodendrocytic basic protein (MOBP), MAG, MBP and proteolipid protein (PLP) in hippocampus, cortex and spinal cord; (4) quantitation of ethanolamine and choline plasmalogens, all core myelin components; (5) evaluation of myelin content in brain sections employing toluidine blue staining; and (6) ultrastructural evaluation of myelin sheath thickness via electron microscopy. We speculate that increased GABA/GHB, acting through GABAergic systems, results in decreased levels of the neurosteroids progesterone and allopregnanolone [Gupta et al (2003) Ann Neurol 54(Supplement 6): S81-S90] and phosphorylation of mitogen-activated protein (MAP) kinase, with resulting myelin protein abnormalities primarily in the cortex of SSADH(-/-) mice.
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Affiliation(s)
- Elizabeth A Donarum
- Developmental Neurogenetics Research Laboratory, Barrow Neurological Institute, Phoenix, Arizona, USA
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Jansen EEW, Gibson KM, Shigematsu Y, Jakobs C, Verhoeven NM. A novel, quantitative assay for homocarnosine in cerebrospinal fluid using stable-isotope dilution liquid chromatography–tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2006; 830:196-200. [PMID: 16309980 DOI: 10.1016/j.jchromb.2005.10.053] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 10/21/2005] [Accepted: 10/26/2005] [Indexed: 11/24/2022]
Abstract
We describe a rapid and sensitive method for the quantification of homocarnosine in physiological fluids, with particular emphasis on cerebrospinal fluid (CSF). Homocarnosine was quantified as the butyl derivative, with (2)H(2)-l-homocarnosine as internal standard. Following deproteinization of CSF samples, supernatants were evaporated to dryness and derivatized with 10% 6M HCl in butanol. Samples were chromatographed on a C(18) column and detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS) operating in the multiple reaction monitoring mode. The intra- and inter-assay variations were 4.6 and 10.9%, respectively. Mean recovery of homocarnosine at two concentrations was 105%. The limit of detection in CSF approximated 20 nmol/L. CSF homocarnosine is age dependent and ranges from <0.02 to 10 micromol/L. Our method is applicable to the analysis of CSF derived from patients with heritable defects in the GABA pathway, patients with homocarnosinosis or serum carnosinase deficiency, and should be applicable to other model systems in order to further explore the biological role and significance of homocarnosine in mammalian systems.
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Affiliation(s)
- Erwin E W Jansen
- Metabolic Unit, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands
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Held PK, Al-Dhalimy M, Willenbring H, Akkari Y, Jiang S, Torimaru Y, Olson S, Fleming WH, Finegold M, Grompe M. In Vivo Genetic Selection of Renal Proximal Tubules. Mol Ther 2006; 13:49-58. [PMID: 16216560 DOI: 10.1016/j.ymthe.2005.09.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 08/19/2005] [Accepted: 09/06/2005] [Indexed: 01/06/2023] Open
Abstract
Repopulation by transplanted cells can result in effective therapy for several regenerative organs including blood, liver, and skin. In contrast, cell therapies for renal diseases are not currently available. Here we developed an animal model in which cells genetically resistant to a toxic intermediate of tyrosine metabolism, homogentisic acid (HGA), were able to repopulate the damaged proximal tubule epithelium of mice with fumarylacetoacetate hydrolase (Fah) deficiency. HGA resistance was achieved by two independent mechanisms. First, Fah+ transplanted bone marrow cells produced significant replacement of damaged proximal tubular epithelium (up to 50%). The majority of bone marrow-derived epithelial cells were generated by cell fusion, not transdifferentiation. In addition to regeneration by fusion-derived epithelial cells, proximal tubular repopulation was also observed by host epithelial cells, which had lost the homogentisic acid dioxygenase gene. These data demonstrate that extensive regeneration of the renal proximal tubule compartment can be achieved through genetic selection of functional cells.
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Affiliation(s)
- Patrice K Held
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97239, USA
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Gibson KM, Jakobs C, Pearl PL, Snead OC. Murine succinate semialdehyde dehydrogenase (SSADH) deficiency, a heritable disorder of GABA metabolism with epileptic phenotype. IUBMB Life 2005; 57:639-44. [PMID: 16203683 DOI: 10.1080/15216540500264588] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Murine models of inborn errors of metabolism represent an established approach for investigating pathophysiological mechanisms associated with the corresponding human disorder. Our laboratory studies human inherited defects of GABA synthesis and degradation. One of these, succinate semialdehyde dehydrogenase (SSADH) deficiency (or gamma-hydroxybutyric aciduria; OMIM 271980; E.C. 1.2.1.24), has recently been modeled via gene targeting in the mouse. SSADH-/- mice succumb to early lethality in status epilepticus at postnatal (PN) days 20 - 26. Numerous metabolic, neurochemical and neurophysiological abnormalities have been documented using in vitro and in vivo approaches, substantially altering our thoughts about the complexity of the corresponding human condition. Moreover, novel preclinical treatment paradigms have been developed through drug trials in gene-ablated animals. The greatest utility of this animal, however, may reside in its transition from early absence seizures to generalized convulsions and eventual status epilepticus. Accurate neurochemical assessment during this transition may provide clues to the same transition process in patients, for which the underlying mechanisms remain undefined.
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Affiliation(s)
- K M Gibson
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, USA.
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Tauer U, Lorenz S, Lenzen KP, Heils A, Muhle H, Gresch M, Neubauer BA, Waltz S, Rudolf G, Mattheisen M, Strauch K, Nürnberg P, Schmitz B, Stephani U, Sander T. Genetic dissection of photosensitivity and its relation to idiopathic generalized epilepsy. Ann Neurol 2005; 57:866-73. [PMID: 15929039 DOI: 10.1002/ana.20500] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Photosensitivity or photoparoxysmal response (PPR) is a common and highly heritable electroencephalographic trait characterized by an abnormal visual sensitivity of the brain in reaction to intermittent photic stimulation. PPR occurs frequently associated with idiopathic generalized epilepsies (IGEs). The present genomewide linkage scan was designed to map susceptibility loci for PPR and to explore their genetic relationship with IGE. The study included 60 families with at least two siblings displaying PPR. To dissect PPR-specific and IGE-related susceptibility loci, we defined two distinct family subgroups, comprising 19 families with predominantly pure PPR and photosensitive seizures (PPR-families) and 25 families, in which PPR was strongly associated with IGE (PPR/IGE-families). MOD score analyses provided significant evidence for linkage to the region 6p21.2 in the PPR-families (empirical p = 0.00004) and suggestive evidence for linkage to the region 13q31.3 in the PPR/IGE families (p = 0.00015), both with a best-fitting recessive mode of inheritance. In the PPR/IGE-families, linkage evidence was even stronger (p = 0.00003) when the trait definition was broadened by IGE traits. Our study shows two PPR-related susceptibility loci, depending on the familial background of IGE. The locus on 6p21.2 seems to predispose to PPR itself, whereas the locus on 13q31.3 also confers susceptibility to IGE.
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Affiliation(s)
- Ulrike Tauer
- Clinic for Neuropaediatrics, University Clinics Schleswig Holstein, Campus Kiel, Kiel, Germany
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