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Balboni N, Babini G, Poeta E, Protti M, Mercolini L, Magnifico MC, Barile SN, Massenzio F, Pignataro A, Giorgi FM, Lasorsa FM, Monti B. Transcriptional and metabolic effects of aspartate-glutamate carrier isoform 1 (AGC1) downregulation in mouse oligodendrocyte precursor cells (OPCs). Cell Mol Biol Lett 2024; 29:44. [PMID: 38553684 PMCID: PMC10979587 DOI: 10.1186/s11658-024-00563-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 03/20/2024] [Indexed: 04/02/2024] Open
Abstract
Aspartate-glutamate carrier isoform 1 (AGC1) is a carrier responsible for the export of mitochondrial aspartate in exchange for cytosolic glutamate and is part of the malate-aspartate shuttle, essential for the balance of reducing equivalents in the cells. In the brain, mutations in SLC25A12 gene, encoding for AGC1, cause an ultra-rare genetic disease, reported as a neurodevelopmental encephalopathy, whose symptoms include global hypomyelination, arrested psychomotor development, hypotonia and seizures. Among the biological components most affected by AGC1 deficiency are oligodendrocytes, glial cells responsible for myelination processes, and their precursors [oligodendrocyte progenitor cells (OPCs)]. The AGC1 silencing in an in vitro model of OPCs was documented to cause defects of proliferation and differentiation, mediated by alterations of histone acetylation/deacetylation. Disrupting AGC1 activity could possibly reduce the availability of acetyl groups, leading to perturbation of many biological pathways, such as histone modifications and fatty acids formation for myelin production. Here, we explore the transcriptome of mouse OPCs partially silenced for AGC1, reporting results of canonical analyses (differential expression) and pathway enrichment analyses, which highlight a disruption in fatty acids synthesis from both a regulatory and enzymatic stand. We further investigate the cellular effects of AGC1 deficiency through the identification of most affected transcriptional networks and altered alternative splicing. Transcriptional data were integrated with differential metabolite abundance analysis, showing downregulation of several amino acids, including glutamine and aspartate. Taken together, our results provide a molecular foundation for the effects of AGC1 deficiency in OPCs, highlighting the molecular mechanisms affected and providing a list of actionable targets to mitigate the effects of this pathology.
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Affiliation(s)
- Nicola Balboni
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Giorgia Babini
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Eleonora Poeta
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Michele Protti
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Laura Mercolini
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Maria Chiara Magnifico
- Department of Biosciences, Biotechnologies and Environment, University of Bari, Bari, Italy
| | - Simona Nicole Barile
- Department of Biosciences, Biotechnologies and Environment, University of Bari, Bari, Italy
| | - Francesca Massenzio
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Antonella Pignataro
- Department of Biosciences, Biotechnologies and Environment, University of Bari, Bari, Italy
| | - Federico M Giorgi
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
| | | | - Barbara Monti
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
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2
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Pardo B, Herrada-Soler E, Satrústegui J, Contreras L, del Arco A. AGC1 Deficiency: Pathology and Molecular and Cellular Mechanisms of the Disease. Int J Mol Sci 2022; 23:528. [PMID: 35008954 PMCID: PMC8745132 DOI: 10.3390/ijms23010528] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/23/2021] [Accepted: 12/24/2021] [Indexed: 02/01/2023] Open
Abstract
AGC1/Aralar/Slc25a12 is the mitochondrial carrier of aspartate-glutamate, the regulatory component of the NADH malate-aspartate shuttle (MAS) that transfers cytosolic redox power to neuronal mitochondria. The deficiency in AGC1/Aralar leads to the human rare disease named "early infantile epileptic encephalopathy 39" (EIEE 39, OMIM # 612949) characterized by epilepsy, hypotonia, arrested psychomotor neurodevelopment, hypo myelination and a drastic drop in brain aspartate (Asp) and N-acetylaspartate (NAA). Current evidence suggest that neurons are the main brain cell type expressing Aralar. However, paradoxically, glial functions such as myelin and Glutamine (Gln) synthesis are markedly impaired in AGC1 deficiency. Herein, we discuss the role of the AGC1/Aralar-MAS pathway in neuronal functions such as Asp and NAA synthesis, lactate use, respiration on glucose, glutamate (Glu) oxidation and other neurometabolic aspects. The possible mechanism triggering the pathophysiological findings in AGC1 deficiency, such as epilepsy and postnatal hypomyelination observed in humans and mice, are also included. Many of these mechanisms arise from findings in the aralar-KO mice model that extensively recapitulate the human disease including the astroglial failure to synthesize Gln and the dopamine (DA) mishandling in the nigrostriatal system. Epilepsy and DA mishandling are a direct consequence of the metabolic defect in neurons due to AGC1/Aralar deficiency. However, the deficits in myelin and Gln synthesis may be a consequence of neuronal affectation or a direct effect of AGC1/Aralar deficiency in glial cells. Further research is needed to clarify this question and delineate the transcellular metabolic fluxes that control brain functions. Finally, we discuss therapeutic approaches successfully used in AGC1-deficient patients and mice.
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Affiliation(s)
- Beatriz Pardo
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Eduardo Herrada-Soler
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Jorgina Satrústegui
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Laura Contreras
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Araceli del Arco
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro Regional de Investigaciones Biomédicas, Facultad de Ciencias Ambientales y Bioquímica, Universidad de Castilla La Mancha, 45071 Toledo, Spain
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3
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Petralla S, Peña-Altamira LE, Poeta E, Massenzio F, Virgili M, Barile SN, Sbano L, Profilo E, Corricelli M, Danese A, Giorgi C, Ostan R, Capri M, Pinton P, Palmieri F, Lasorsa FM, Monti B. Deficiency of Mitochondrial Aspartate-Glutamate Carrier 1 Leads to Oligodendrocyte Precursor Cell Proliferation Defects Both In Vitro and In Vivo. Int J Mol Sci 2019; 20:ijms20184486. [PMID: 31514314 PMCID: PMC6769484 DOI: 10.3390/ijms20184486] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/04/2019] [Accepted: 09/06/2019] [Indexed: 11/16/2022] Open
Abstract
Aspartate-Glutamate Carrier 1 (AGC1) deficiency is a rare neurological disease caused by mutations in the solute carrier family 25, member 12 (SLC25A12) gene, encoding for the mitochondrial aspartate-glutamate carrier isoform 1 (AGC1), a component of the malate-aspartate NADH shuttle (MAS), expressed in excitable tissues only. AGC1 deficiency patients are children showing severe hypotonia, arrested psychomotor development, seizures and global hypomyelination. While the effect of AGC1 deficiency in neurons and neuronal function has been deeply studied, little is known about oligodendrocytes and their precursors, the brain cells involved in myelination. Here we studied the effect of AGC1 down-regulation on oligodendrocyte precursor cells (OPCs), using both in vitro and in vivo mouse disease models. In the cell model, we showed that a reduced expression of AGC1 induces a deficit of OPC proliferation leading to their spontaneous and precocious differentiation into oligodendrocytes. Interestingly, this effect seems to be related to a dysregulation in the expression of trophic factors and receptors involved in OPC proliferation/differentiation, such as Platelet-Derived Growth Factor α (PDGFα) and Transforming Growth Factor βs (TGFβs). We also confirmed the OPC reduction in vivo in AGC1-deficent mice, as well as a proliferation deficit in neurospheres from the Subventricular Zone (SVZ) of these animals, thus indicating that AGC1 reduction could affect the proliferation of different brain precursor cells. These data clearly show that AGC1 impairment alters myelination not only by acting on N-acetyl-aspartate production in neurons but also on OPC proliferation and suggest new potential therapeutic targets for the treatment of AGC1 deficiency.
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Affiliation(s)
- Sabrina Petralla
- Department of Pharmacy and BioTechnology, University of Bologna, 40126 Bologna, Italy; (S.P.); (L.E.P.-A.); (E.P.); (F.M.); (M.V.)
| | - Luis Emiliano Peña-Altamira
- Department of Pharmacy and BioTechnology, University of Bologna, 40126 Bologna, Italy; (S.P.); (L.E.P.-A.); (E.P.); (F.M.); (M.V.)
| | - Eleonora Poeta
- Department of Pharmacy and BioTechnology, University of Bologna, 40126 Bologna, Italy; (S.P.); (L.E.P.-A.); (E.P.); (F.M.); (M.V.)
| | - Francesca Massenzio
- Department of Pharmacy and BioTechnology, University of Bologna, 40126 Bologna, Italy; (S.P.); (L.E.P.-A.); (E.P.); (F.M.); (M.V.)
| | - Marco Virgili
- Department of Pharmacy and BioTechnology, University of Bologna, 40126 Bologna, Italy; (S.P.); (L.E.P.-A.); (E.P.); (F.M.); (M.V.)
| | - Simona Nicole Barile
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70121 Bari, Italy (E.P.); (F.P.)
| | - Luigi Sbano
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy; (L.S.); (M.C.); (A.D.); (C.G.); (P.P.)
| | - Emanuela Profilo
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70121 Bari, Italy (E.P.); (F.P.)
| | - Mariangela Corricelli
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy; (L.S.); (M.C.); (A.D.); (C.G.); (P.P.)
| | - Alberto Danese
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy; (L.S.); (M.C.); (A.D.); (C.G.); (P.P.)
| | - Carlotta Giorgi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy; (L.S.); (M.C.); (A.D.); (C.G.); (P.P.)
| | - Rita Ostan
- Department of Experimental, Diagnostic and Specialty Medicine (DIMES, Dipartimento di Medicina Specialistica Diagnostica e Sperimentale) and C.I.G. Interdepartmental Centre “L. Galvani”, University of Bologna, 40126 Bologna, Italy; (R.O.); (M.C.)
| | - Miriam Capri
- Department of Experimental, Diagnostic and Specialty Medicine (DIMES, Dipartimento di Medicina Specialistica Diagnostica e Sperimentale) and C.I.G. Interdepartmental Centre “L. Galvani”, University of Bologna, 40126 Bologna, Italy; (R.O.); (M.C.)
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy; (L.S.); (M.C.); (A.D.); (C.G.); (P.P.)
- Maria Cecilia Hospital, GVM Care & Research, Cotignola, 48010 Ravenna, Italy
| | - Ferdinando Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70121 Bari, Italy (E.P.); (F.P.)
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies IBIOM, CNR, 70126 Bari, Italy
| | - Francesco Massimo Lasorsa
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies IBIOM, CNR, 70126 Bari, Italy
- Correspondence: (F.M.L.); (B.M.); Tel.: +39-080-544-2772 (F.M.L.); +39-051-209-4134 (B.M.)
| | - Barbara Monti
- Department of Pharmacy and BioTechnology, University of Bologna, 40126 Bologna, Italy; (S.P.); (L.E.P.-A.); (E.P.); (F.M.); (M.V.)
- Correspondence: (F.M.L.); (B.M.); Tel.: +39-080-544-2772 (F.M.L.); +39-051-209-4134 (B.M.)
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4
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Tochigi Y, Takamatsu Y, Nakane J, Nakai R, Katayama K, Suzuki H. Loss of Wwox Causes Defective Development of Cerebral Cortex with Hypomyelination in a Rat Model of Lethal Dwarfism with Epilepsy. Int J Mol Sci 2019; 20:ijms20143596. [PMID: 31340538 PMCID: PMC6678113 DOI: 10.3390/ijms20143596] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/20/2019] [Accepted: 07/22/2019] [Indexed: 12/20/2022] Open
Abstract
WW domain-containing oxidoreductase (Wwox) is a putative tumor suppressor. Several germline mutations of Wwox have been associated with infant neurological disorders characterized by epilepsy, growth retardation, and early death. Less is known, however, about the pathological link between Wwox mutations and these disorders or the physiological role of Wwox in brain development. In this study, we examined age-related expression and histological localization of Wwox in forebrains as well as the effects of loss of function mutations in the Wwox gene in the immature cortex of a rat model of lethal dwarfism with epilepsy (lde/lde). Immunostaining revealed that Wwox is expressed in neurons, astrocytes, and oligodendrocytes. lde/lde cortices were characterized by a reduction in neurite growth without a reduced number of neurons, severe reduction in myelination with a reduced number of mature oligodendrocytes, and a reduction in cell populations of astrocytes and microglia. These results indicate that Wwox is essential for normal development of neurons and glial cells in the cerebral cortex.
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Affiliation(s)
- Yuki Tochigi
- Laboratory of Veterinary Physiology, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan
| | - Yutaka Takamatsu
- Laboratory of Veterinary Physiology, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan
| | - Jun Nakane
- Laboratory of Veterinary Physiology, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan
| | - Rika Nakai
- Laboratory of Veterinary Physiology, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan
| | - Kentaro Katayama
- Laboratory of Veterinary Physiology, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan
| | - Hiroetsu Suzuki
- Laboratory of Veterinary Physiology, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan.
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5
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Rodan LH, Qi W, Ducker GS, Demirbas D, Laine R, Yang E, Walker MA, Eichler F, Rabinowitz JD, Anselm I, Berry GT. 5,10-methenyltetrahydrofolate synthetase deficiency causes a neurometabolic disorder associated with microcephaly, epilepsy, and cerebral hypomyelination. Mol Genet Metab 2018; 125:118-126. [PMID: 30031689 PMCID: PMC6557438 DOI: 10.1016/j.ymgme.2018.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 06/12/2018] [Accepted: 06/12/2018] [Indexed: 10/28/2022]
Abstract
Folate metabolism in the brain is critically important and serves a number of vital roles in nucleotide synthesis, single carbon metabolism/methylation, amino acid metabolism, and mitochondrial translation. Genetic defects in almost every enzyme of folate metabolism have been reported to date, and most have neurological sequelae. We report 2 patients presenting with a neurometabolic disorder associated with biallelic variants in the MTHFS gene, encoding 5,10-methenyltetrahydrofolate synthetase. Both patients presented with microcephaly, short stature, severe global developmental delay, progressive spasticity, epilepsy, and cerebral hypomyelination. Baseline CSF 5-methyltetrahydrolate (5-MTHF) levels were in the low-normal range. The first patient was treated with folinic acid, which resulted in worsening cerebral folate deficiency. Treatment in this patient with a combination of oral L-5-methyltetrahydrofolate and intramuscular methylcobalamin was able to increase CSF 5-MTHF levels, was well tolerated over a 4 month period, and resulted in subjective mild improvements in functioning. Measurement of MTHFS enzyme activity in fibroblasts confirmed reduced activity. The direct substrate of the MTHFS reaction, 5-formyl-THF, was elevated 30-fold in patient fibroblasts compared to control, supporting the hypothesis that the pathophysiology of this disorder is a manifestation of toxicity from this metabolite.
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Affiliation(s)
- Lance H Rodan
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
| | - Wanshu Qi
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Gregory S Ducker
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Didem Demirbas
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Regina Laine
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Edward Yang
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Melissa A Walker
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Florian Eichler
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Joshua D Rabinowitz
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Irina Anselm
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Gerard T Berry
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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6
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Nakayama T, Al-Maawali A, El-Quessny M, Rajab A, Khalil S, Stoler JM, Tan WH, Nasir R, Schmitz-Abe K, Hill RS, Partlow JN, Al-Saffar M, Servattalab S, LaCoursiere CM, Tambunan DE, Coulter ME, Elhosary PC, Gorski G, Barkovich AJ, Markianos K, Poduri A, Mochida GH. Mutations in PYCR2, Encoding Pyrroline-5-Carboxylate Reductase 2, Cause Microcephaly and Hypomyelination. Am J Hum Genet 2015; 96:709-19. [PMID: 25865492 PMCID: PMC4570282 DOI: 10.1016/j.ajhg.2015.03.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 03/05/2015] [Indexed: 12/27/2022] Open
Abstract
Despite recent advances in understanding the genetic bases of microcephaly, a large number of cases of microcephaly remain unexplained, suggesting that many microcephaly syndromes and associated genes have yet to be identified. Here, we report mutations in PYCR2, which encodes an enzyme in the proline biosynthesis pathway, as the cause of a unique syndrome characterized by postnatal microcephaly, hypomyelination, and reduced cerebral white-matter volume. Linkage mapping and whole-exome sequencing identified homozygous mutations (c.355C>T [p.Arg119Cys] and c.751C>T [p.Arg251Cys]) in PYCR2 in the affected individuals of two consanguineous families. A lymphoblastoid cell line from one affected individual showed a strong reduction in the amount of PYCR2. When mutant cDNAs were transfected into HEK293FT cells, both variant proteins retained normal mitochondrial localization but had lower amounts than the wild-type protein, suggesting that the variant proteins were less stable. A PYCR2-deficient HEK293FT cell line generated by genome editing with the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 system showed that PYCR2 loss of function led to decreased mitochondrial membrane potential and increased susceptibility to apoptosis under oxidative stress. Morpholino-based knockdown of a zebrafish PYCR2 ortholog, pycr1b, recapitulated the human microcephaly phenotype, which was rescued by wild-type human PYCR2 mRNA, but not by mutant mRNAs, further supporting the pathogenicity of the identified variants. Hypomyelination and the absence of lax, wrinkly skin distinguishes this condition from that caused by previously reported mutations in the gene encoding PYCR2's isozyme, PYCR1, suggesting a unique and indispensable role for PYCR2 in the human CNS during development.
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Affiliation(s)
- Tojo Nakayama
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Almundher Al-Maawali
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Department of Genetics, College of Medicine and Health Science, Sultan Qaboos University, Muscat 123, Oman
| | - Malak El-Quessny
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA
| | - Anna Rajab
- National Genetics Center, Directorate General of Health Affairs, Ministry of Health, Muscat 113, Oman
| | - Samir Khalil
- Department of Pediatrics, Al-Makassed Islamic Charitable Society Hospital, Jerusalem 91220; Faculty of Medicine, Al-Quds University, Jerusalem 90612
| | - Joan M Stoler
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Wen-Hann Tan
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Ramzi Nasir
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Division of Developmental Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Klaus Schmitz-Abe
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - R Sean Hill
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jennifer N Partlow
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Muna Al-Saffar
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Department of Paediatrics, College of Medicine and Health Sciences, United Arab Emirates University, PO Box 17666, Al-Ain, United Arab Emirates
| | - Sarah Servattalab
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | | | - Dimira E Tambunan
- Department of Neurology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Michael E Coulter
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02139, USA
| | - Princess C Elhosary
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Grzegorz Gorski
- Cellular Neuroscience Core, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - A James Barkovich
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Kyriacos Markianos
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Annapurna Poduri
- Department of Neurology, Boston Children's Hospital, Boston, MA 02115, USA; Epilepsy Genetics Program, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Ganeshwaran H Mochida
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Pediatric Neurology Unit, Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA.
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Wongkittichote P, Tungpradabkul S, Wattanasirichaigoon D, Jensen LT. Prediction of the functional effect of novel SLC25A13 variants using a S. cerevisiae model of AGC2 deficiency. J Inherit Metab Dis 2013; 36:821-30. [PMID: 23053473 DOI: 10.1007/s10545-012-9543-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 09/05/2012] [Accepted: 09/12/2012] [Indexed: 01/31/2023]
Abstract
AGC2, a member of the mitochondrial carrier protein family, is as an aspartate-glutamate carrier and is important for urea synthesis and the maintenance of the malate-aspartate shuttle. Mutations in SLC25A13, the gene encoding AGC2, result in two age dependent disorders: neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) and type II citrullinemia (CTLN2). The clinical features of CTLN2 are very similar to those of other urea cycle disorders making a clear diagnosis difficult. Analysis of the SLC25A13 gene sequence can provide a definitive diagnosis, however the predictive value of DNA sequencing requires that the disease association of variants be characterized. We utilized the yeast Saccharomyces cerevisiae lacking AGC1 as a model system to study the effect on the function of AGC2 variants and confirmed that this system is capable of distinguishing between AGC2 variants with normal (p.Pro632Leu) or impaired function (p.Gly437Glu, p.Gly531Asp, p.Thr546Met, p.Leu598Arg and p.Glu601Lys). Three novel AGC2 genetic variants, p.Met1? (c.2T>C), p.Pro502Leu (c.1505C>T), and p.Arg605Gln (c.1814G>A) were investigated and our analysis revealed that p.Pro502Leu and p.Arg605Gln substitutions in the AGC2 protein were without effect and these variants were fully functional. The p.Met1? mutant is capable of expressing a truncated p.Met1_Phe34del AGC2 variant, however this protein is not functional due to disruptions in a calcium binding EF hand as well as incorrect intracellular localization. Our study demonstrates that the characterization of AGC2 expressed in yeast cells is a powerful technique to investigate AGC2 variants, and this analysis should aid in establishing the disease association of novel variants.
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Affiliation(s)
- Parith Wongkittichote
- Graduate Program in Molecular Medicine, Faculty of Science, Mahidol University, Bangkok, Thailand
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Abstract
Cochlear inner hair cells (IHCs) are temporarily innervated by efferent cholinergic fibers prior to the onset of hearing. During low-frequency firing, these efferent synapses have a relatively low probability of transmitter release but facilitate strongly with repetitive stimulation. A retrograde signal from the hair cell to the efferent terminal contributes to this facilitation. When IHCs were treated with the ryanodine receptor agonist, cyclic adenosine phosphoribose (cADPR), release probability of the efferent terminal rose. This effect was quantified by computing the quantum content from a train of 100 suprathreshold stimuli to the efferent fibers. Quantum content was sevenfold higher when IHCs were treated with 100 μM cADPR (applied in the recording pipette). Since cADPR is membrane impermeant, this result implies that an extracellular messenger travels from the hair cell to the efferent terminal. cADPR is presumed to generate this messenger by increasing cytoplasmic calcium. Consistent with this presumption, voltage-gated calcium flux into the IHC also caused retrograde facilitation of efferent transmission. Retrograde facilitation was observed in IHCs of a vesicular glutamate transporter (VGlut3) null mouse and for wild-type rat hair cells subject to wide-spectrum glutamate receptor blockade, demonstrating that glutamate was unlikely to be the extracellular messenger. Rather, bath application of nitric oxide (NO) donors caused an increase in potassium-evoked efferent transmitter release while the NO scavenger carboxy-PTIO was able to prevent retrograde facilitation produced by cADPR or IHC depolarization. Thus, hair cell activity can drive retrograde facilitation of efferent input via calcium-dependent production of NO.
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MESH Headings
- Acoustic Stimulation
- Amino Acid Transport Systems, Acidic/deficiency
- Amino Acid Transport Systems, Acidic/genetics
- Amino Acid Transport Systems, Acidic/metabolism
- Animals
- Calcium/metabolism
- Calcium Channel Agonists/pharmacology
- Dose-Response Relationship, Drug
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/physiology
- Mice
- Mice, Knockout
- Models, Animal
- Neurons, Efferent/drug effects
- Neurons, Efferent/physiology
- Nitric Oxide/metabolism
- Nitric Oxide Donors/pharmacology
- Rats
- Rats, Inbred Strains
- Synapses/drug effects
- Synapses/physiology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- Jee-Hyun Kong
- Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Wibom R, Lasorsa FM, Töhönen V, Barbaro M, Sterky FH, Kucinski T, Naess K, Jonsson M, Pierri CL, Palmieri F, Wedell A. AGC1 deficiency associated with global cerebral hypomyelination. N Engl J Med 2009; 361:489-95. [PMID: 19641205 DOI: 10.1056/nejmoa0900591] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1), specific to neurons and muscle, supplies aspartate to the cytosol and, as a component of the malate-aspartate shuttle, enables mitochondrial oxidation of cytosolic NADH, thought to be important in providing energy for neurons in the central nervous system. We describe AGC1 deficiency, a novel syndrome characterized by arrested psychomotor development, hypotonia, and seizures in a child with a homozygous missense mutation in the solute carrier family 25, member 12, gene SLC25A12, which encodes the AGC1 protein. Functional analysis of the mutant AGC1 protein showed abolished activity. The child had global hypomyelination in the cerebral hemispheres, suggesting that impaired efflux of aspartate from neuronal mitochondria prevents normal myelin formation.
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Affiliation(s)
- Rolf Wibom
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
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Blankenship AG, Ford KJ, Johnson J, Seal RP, Edwards RH, Copenhagen DR, Feller MB. Synaptic and extrasynaptic factors governing glutamatergic retinal waves. Neuron 2009; 62:230-41. [PMID: 19409268 PMCID: PMC2807181 DOI: 10.1016/j.neuron.2009.03.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 01/28/2009] [Accepted: 03/17/2009] [Indexed: 11/28/2022]
Abstract
In the few days prior to eye-opening in mice, the excitatory drive underlying waves switches from cholinergic to glutamatergic. Here, we describe the unique synaptic and spatiotemporal properties of waves generated by the retina's glutamatergic circuits. First, knockout mice lacking vesicular glutamate transporter type 1 do not have glutamatergic waves, but continue to exhibit cholinergic waves, demonstrating that the two wave-generating circuits are linked. Second, simultaneous outside-out patch and whole-cell recordings reveal that retinal waves are accompanied by transient increases in extrasynaptic glutamate, directly demonstrating the existence of glutamate spillover during waves. Third, the initiation rate and propagation speed of retinal waves, as assayed by calcium imaging, are sensitive to pharmacological manipulations of spillover and inhibition, demonstrating a role for both signaling pathways in shaping the spatiotemporal properties of glutamatergic retinal waves.
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Affiliation(s)
- Aaron G Blankenship
- Neurosciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
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12
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Amilhon B, El Mestikawy S. [VGLUT3, an unsuspected agent of striatal cholinergic transmission]. Med Sci (Paris) 2009; 24:1009-11. [PMID: 19116102 DOI: 10.1051/medsci/200824121009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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