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Lee A, Henderson R, Aylward J, McCombe P. Gut Symptoms, Gut Dysbiosis and Gut-Derived Toxins in ALS. Int J Mol Sci 2024; 25:1871. [PMID: 38339149 PMCID: PMC10856138 DOI: 10.3390/ijms25031871] [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: 01/04/2024] [Revised: 01/31/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024] Open
Abstract
Many pathogenetic mechanisms have been proposed for amyotrophic lateral sclerosis (ALS). Recently, there have been emerging suggestions of a possible role for the gut microbiota. Gut microbiota have a range of functions and could influence ALS by several mechanisms. Here, we review the possible role of gut-derived neurotoxins/excitotoxins. We review the evidence of gut symptoms and gut dysbiosis in ALS. We then examine a possible role for gut-derived toxins by reviewing the evidence that these molecules are toxic to the central nervous system, evidence of their association with ALS, the existence of biochemical pathways by which these molecules could be produced by the gut microbiota and existence of mechanisms of transport from the gut to the blood and brain. We then present evidence that there are increased levels of these toxins in the blood of some ALS patients. We review the effects of therapies that attempt to alter the gut microbiota or ameliorate the biochemical effects of gut toxins. It is possible that gut dysbiosis contributes to elevated levels of toxins and that these could potentially contribute to ALS pathogenesis, but more work is required.
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Affiliation(s)
- Aven Lee
- Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4029, Australia; (R.H.); (P.M.)
| | - Robert Henderson
- Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4029, Australia; (R.H.); (P.M.)
- Department of Neurology, Royal Brisbane & Women’s Hospital, Brisbane, QLD 4029, Australia
- Wesley Research Institute, The Wesley Hospital, Auchenflower, QLD 4066, Australia;
| | - James Aylward
- Wesley Research Institute, The Wesley Hospital, Auchenflower, QLD 4066, Australia;
| | - Pamela McCombe
- Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4029, Australia; (R.H.); (P.M.)
- Department of Neurology, Royal Brisbane & Women’s Hospital, Brisbane, QLD 4029, Australia
- Wesley Research Institute, The Wesley Hospital, Auchenflower, QLD 4066, Australia;
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2
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Dave U, Narain P, Mishra D, Gomes J. Aggregation of E121K mutant D-amino acid oxidase and ubiquitination-mediated autophagy mechanisms leading to amyotrophic lateral sclerosis. J Neurol Sci 2024; 456:122845. [PMID: 38134563 DOI: 10.1016/j.jns.2023.122845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 11/04/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023]
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a terminal adult-onset neuromuscular disorder. Our group has been studying this illness and previously reported novel mutations and rare mutations in a study using next-generation sequencing of DNA samples from Indian ALS patients. In this paper, we focus on the E121K mutation in the DAO gene to understand how it leads to ALS. Our experiments in SH-SY5Y cells indicate that the E121K mutation results in the accumulation of mutant protein aggregates, a change in cell morphology, and the death of neuronal cells. These protein aggregates get ubiquitinated and cause an imbalance in autophagy regulation. We observed an increase in the cellular concentrations of p62, OPTN, and LC3II. Through confocal microscopy studies, we show that the binding of p62 with ubiquitinated aggregates and its recruitment to LC3II mediates autophagosome generation. These relative changes in the key partners in autophagy increase cell death in cells harboring the E121K mutation and is a probable mechanism leading to ALS.
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Affiliation(s)
- Upma Dave
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Priyam Narain
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Dibyakanti Mishra
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - James Gomes
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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3
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Khan S, Upadhyay S, Dave U, Kumar A, Gomes J. Structural and mechanistic insights into ALS patient derived mutations in D-amino acid oxidase. Int J Biol Macromol 2024; 256:128403. [PMID: 38035964 DOI: 10.1016/j.ijbiomac.2023.128403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/19/2023] [Accepted: 11/22/2023] [Indexed: 12/02/2023]
Abstract
The D-amino acid oxidase protein modulates neurotransmission by controlling the levels of D-serine, a co-agonist of N-methyl-D-aspartate receptors. Mutations in the DAO gene have been associated with ALS, with some studies reporting pathogenic mechanisms of the R199W mutation. We have characterized two novel mutations R38H and Q201R found in ALS patients and report certain novel findings related to the R199W mutation. We report the first instance of crystal structure analysis of a patient-derived mutant of DAO, R38H, solved at 2.10 Å. The structure revealed significant perturbations and altered binding with the cofactor (FAD) and the inhibitor benzoate, supported by biochemical assays. Q201R-DAO also exhibited significantly lower ligand binding efficiency. Furthermore, kinetic analysis across all variants revealed reduced oxidase activity and substrate binding. Notably, R38H-DAO exhibited near-WT activity only at high substrate concentrations, while R199W-DAO and Q201R-DAO displayed drastic activity reduction. Additionally, structural perturbations were inferred for R199W-DAO and Q201R-DAO, evident by the higher oligomeric state in the holoenzyme form. We also observed thermal instability in case of R199W-DAO mutant. We hypothesize that the mutant enzymes may be rendered non-functional in a cellular context, potentially leading to NMDAR-associated excitotoxicity. The study provides novel insights into structural and functional aspects of DAO mutations in ALS.
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Affiliation(s)
- Shumayila Khan
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi 110016, India; Indian Council of Medical Research, New Delhi 110029, India
| | - Saurabh Upadhyay
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi 110016, India
| | - Upma Dave
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi 110016, India
| | - Ashwani Kumar
- Macromolecular Crystallography Section, Beamline Development & Application Section, Bhabha Atomic Research Center, Trombay, Mumbai 400085, India
| | - James Gomes
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi 110016, India.
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4
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Dave U, Khan S, Gomes J. Characterization of E121K mutation of D-amino acid oxidase - Insights into mechanisms leading to amyotrophic lateral sclerosis. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2023; 1871:140947. [PMID: 37558109 DOI: 10.1016/j.bbapap.2023.140947] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023]
Abstract
D-amino acid oxidase (DAO) maintains the intracellular d-serine level which modulates the activity of the N-methyl-d-aspartate receptor and its dysfunction has been linked to several neurodegenerative disorders. In targeted next-generation sequencing study by our group, E121K mutation in DAO was associated with amyotrophic lateral sclerosis (ALS) in patients from India. However, variations in molecular mechanisms caused by this mutation which leads to ALS have not been studied. Hence, we carried out comparative biophysical characterization and assay studies of the wildtype- and mutant E121K-DAO. We observed that the purified E121K-DAO was inactive and exhibited a lower affinity for the FAD cofactor and benzoate inhibitor. Structural studies revealed that the E121K mutant has higher beta-sheet content, melting temperature, and oligomeric states compared to the wildtype. Kinetic study of aggregation of the variants using thioflavin-T confirmed that the E121K-DAO was more prone to aggregation. Microscopic visualization showed that the aggregation proceeds through an intermediate step involving the formation of fibrillar structures in the E121K mutant. Our results give insights into the underlying mechanisms leading to ALS pathogenesis.
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Affiliation(s)
- Upma Dave
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shumayila Khan
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - James Gomes
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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5
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Ji R, Shen J. Chirality Transformation in Metathesis Reactions of Salicylaldehyde/Pyridoxal‐Based Imines. ChemistrySelect 2022. [DOI: 10.1002/slct.202201332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Rui‐Xue Ji
- Xiamen Key Laboratory of Optoelectronic Materials and Advanced Manufacturing College of Materials Science and Engineering Huaqiao University Xiamen 361021 China
| | - Jiang‐Shan Shen
- Xiamen Key Laboratory of Optoelectronic Materials and Advanced Manufacturing College of Materials Science and Engineering Huaqiao University Xiamen 361021 China
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6
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Gonda Y, Ishii C, Mita M, Nishizaki N, Ohtomo Y, Hamase K, Shimizu T, Sasabe J. Astrocytic D -amino acid oxidase degrades D -serine in the hindbrain. FEBS Lett 2022; 596:2889-2897. [PMID: 35665501 DOI: 10.1002/1873-3468.14417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/22/2022] [Accepted: 05/25/2022] [Indexed: 11/11/2022]
Abstract
D -serine modulates excitatory neurotransmission by binding to N-methyl-D -aspartate glutamate receptors. D- amino acid oxidase (DAO) degrades D -amino acids, such as D -serine, in the central nervous system, and is associated with neurological and psychiatric disorders. However, cell types that express brain DAO remain controversial, and whether brain DAO influences systemic D -amino acids in addition to brain D -serine remains unclear. Here, we created astrocyte-specific DAO-conditional knockout mice. Knockout in glial fibrillary acidic protein (GFAP)-positive cells eliminated DAO expression in the hindbrain and increased D -serine levels significantly in the cerebellum. Brain DAO did not influence levels of D -amino acids in the forebrain or periphery. These results show that astrocytic DAO regulates D -serine specifically in the hindbrain.
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Affiliation(s)
- Yusuke Gonda
- Department of Pharmacology, Keio University School of Medicine, 160-8582, Tokyo, Japan.,Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate school of Medicine, 113-8431, Tokyo, Japan
| | - Chiharu Ishii
- Graduate School of Pharmaceutical Sciences, Kyushu University, 812-8582, Fukuoka, Japan
| | | | - Naoto Nishizaki
- Department of Pediatrics, Juntendo University Urayasu Hospital, 279-0021, Chiba, Japan
| | - Yoshiyuki Ohtomo
- Department of Pediatrics, Juntendo University Nerima Hospital, 177-8521, Tokyo, Japan
| | - Kenji Hamase
- Graduate School of Pharmaceutical Sciences, Kyushu University, 812-8582, Fukuoka, Japan
| | - Toshiaki Shimizu
- Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate school of Medicine, 113-8431, Tokyo, Japan
| | - Jumpei Sasabe
- Department of Pharmacology, Keio University School of Medicine, 160-8582, Tokyo, Japan
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7
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Todd TW, Petrucelli L. Modelling amyotrophic lateral sclerosis in rodents. Nat Rev Neurosci 2022; 23:231-251. [PMID: 35260846 DOI: 10.1038/s41583-022-00564-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2022] [Indexed: 12/11/2022]
Abstract
The efficient study of human disease requires the proper tools, one of the most crucial of which is an accurate animal model that faithfully recapitulates the human condition. The study of amyotrophic lateral sclerosis (ALS) is no exception. Although the majority of ALS cases are considered sporadic, most animal models of this disease rely on genetic mutations identified in familial cases. Over the past decade, the number of genes associated with ALS has risen dramatically and, with each new genetic variant, there is a drive to develop associated animal models. Rodent models are of particular importance as they allow for the study of ALS in the context of a living mammal with a comparable CNS. Such models not only help to verify the pathogenicity of novel mutations but also provide critical insight into disease mechanisms and are crucial for the testing of new therapeutics. In this Review, we aim to summarize the full spectrum of ALS rodent models developed to date.
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Affiliation(s)
- Tiffany W Todd
- Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL, USA
| | - Leonard Petrucelli
- Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL, USA.
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8
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Montibeller L, Tan LY, Kim JK, Paul P, de Belleroche J. Tissue-selective regulation of protein homeostasis and unfolded protein response signalling in sporadic ALS. J Cell Mol Med 2020; 24:6055-6069. [PMID: 32324341 PMCID: PMC7294118 DOI: 10.1111/jcmm.15170] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/21/2020] [Accepted: 02/24/2020] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a disorder that affects motor neurons in motor cortex and spinal cord, and the degeneration of both neuronal populations is a critical feature of the disease. Abnormalities in protein homeostasis (proteostasis) are well established in ALS. However, they have been investigated mostly in spinal cord but less so in motor cortex. Herein, we monitored the unfolded protein (UPR) and heat shock response (HSR), two major proteostasis regulatory pathways, in human post‐mortem tissue derived from the motor cortex of sporadic ALS (SALS) and compared them to those occurring in spinal cord. Although the UPR was activated in both tissues, specific expression of select UPR target genes, such as PDIs, was observed in motor cortex of SALS cases strongly correlating with oligodendrocyte markers. Moreover, we found that endoplasmic reticulum‐associated degradation (ERAD) and HSR genes, which were activated predominately in spinal cord, correlated with the expression of neuronal markers. Our results indicate that proteostasis is strongly and selectively activated in SALS motor cortex and spinal cord where subsets of these genes are associated with specific cell type. This study expands our understanding of convergent molecular mechanisms occurring in motor cortex and spinal cord and highlights cell type–specific contributions.
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Affiliation(s)
- Luigi Montibeller
- Neurogenetics Group, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Li Yi Tan
- Neurogenetics Group, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Joo Kyung Kim
- Neurogenetics Group, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Praveen Paul
- Neurogenetics Group, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Jacqueline de Belleroche
- Neurogenetics Group, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
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9
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Abstract
Motor neuron disorders are highly debilitating and mostly fatal conditions for which only limited therapeutic options are available. To overcome this limitation and develop more effective therapeutic strategies, it is critical to discover the pathogenic mechanisms that trigger and sustain motor neuron degeneration with the greatest accuracy and detail. In the case of Amyotrophic Lateral Sclerosis (ALS), several genes have been associated with familial forms of the disease, whilst the vast majority of cases develop sporadically and no defined cause can be held responsible. On the contrary, the huge majority of Spinal Muscular Atrophy (SMA) occurrences are caused by loss-of-function mutations in a single gene, SMN1. Although the typical hallmark of both diseases is the loss of motor neurons, there is increasing awareness that pathological lesions are also present in the neighbouring glia, whose dysfunction clearly contributes to generating a toxic environment in the central nervous system. Here, ALS and SMA are sequentially presented, each disease section having a brief introduction, followed by a focussed discussion on the role of the astrocytes in the disease pathogenesis. Such a dissertation is substantiated by the findings that built awareness on the glial involvement and how the glial-neuronal interplay is perturbed, along with the appraisal of this new cellular site for possible therapeutic intervention.
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10
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Kim SH, Shishido Y, Sogabe H, Rachadech W, Yorita K, Kato Y, Fukui K. Age- and gender-dependent D-amino acid oxidase activity in mouse brain and peripheral tissues: implication for aging and neurodegeneration. J Biochem 2019; 166:187-196. [DOI: 10.1093/jb/mvz025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/01/2019] [Indexed: 12/11/2022] Open
Abstract
Abstract
D-amino acid oxidase (DAO) is a flavoenzyme, catalysing oxidative deamination of D-amino acids to produce corresponding α-keto acids, ammonia and hydrogen peroxide. In our search for DAO activity among various tissues, we developed a sensitive assay based on hydrogen peroxide production involving enzyme-coupled colorimetric assay with peroxidase. We first optimized buffer components to extract DAO protein from mouse tissues. Here we show that DAO activity was detected in kidney, cerebellum, medulla oblongata, midbrain and spinal cord, but not in liver. In addition, we observed that DAO activity and expression were decreased in thoracic and lumbar regions of spinal cord in aged mice when compared with young mice, indicating that decreased DAO is involved in motoneuron degeneration during senescence. We also found gender difference in DAO activity in the kidney, suggesting that DAO activity is influenced by sexual dimorphism. We newly detected DAO activity in the epididymis, although undetected in testis. Furthermore, DAO activity was significantly higher in the caput region than corpus and cauda regions of epididymis, indicating that D-amino acids present in the testis are eliminated in epididymis. Taken together, age- and gender-dependent DAO activity in each organ may underlie the human pathophysiology regulated by D-amino acid metabolism.
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Affiliation(s)
- Soo Hyeon Kim
- Division of Enzyme Pathophysiology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto, Tokushima, Japan
| | - Yuji Shishido
- Division of Enzyme Pathophysiology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto, Tokushima, Japan
| | - Hirofumi Sogabe
- Division of Enzyme Pathophysiology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto, Tokushima, Japan
| | - Wanitcha Rachadech
- Division of Enzyme Pathophysiology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto, Tokushima, Japan
| | - Kazuko Yorita
- Division of Enzyme Pathophysiology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto, Tokushima, Japan
| | - Yusuke Kato
- Division of Enzyme Pathophysiology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto, Tokushima, Japan
| | - Kiyoshi Fukui
- Division of Enzyme Pathophysiology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto, Tokushima, Japan
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11
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Pollegioni L, Sacchi S, Murtas G. Human D-Amino Acid Oxidase: Structure, Function, and Regulation. Front Mol Biosci 2018; 5:107. [PMID: 30547037 PMCID: PMC6279847 DOI: 10.3389/fmolb.2018.00107] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 11/12/2018] [Indexed: 12/11/2022] Open
Abstract
D-Amino acid oxidase (DAAO) is an FAD-containing flavoenzyme that catalyzes with absolute stereoselectivity the oxidative deamination of all natural D-amino acids, the only exception being the acidic ones. This flavoenzyme plays different roles during evolution and in different tissues in humans. Its three-dimensional structure is well conserved during evolution: minute changes are responsible for the functional differences between enzymes from microorganism sources and those from humans. In recent years several investigations focused on human DAAO, mainly because of its role in degrading the neuromodulator D-serine in the central nervous system. D-Serine is the main coagonist of N-methyl D-aspartate receptors, i.e., excitatory amino acid receptors critically involved in main brain functions and pathologic conditions. Human DAAO possesses a weak interaction with the FAD cofactor; thus, in vivo it should be largely present in the inactive, apoprotein form. Binding of active-site ligands and the substrate stabilizes flavin binding, thus pushing the acquisition of catalytic competence. Interestingly, the kinetic efficiency of the enzyme on D-serine is very low. Human DAAO interacts with various proteins, in this way modulating its activity, targeting, and cell stability. The known properties of human DAAO suggest that its activity must be finely tuned to fulfill a main physiological function such as the control of D-serine levels in the brain. At present, studies are focusing on the epigenetic modulation of human DAAO expression and the role of post-translational modifications on its main biochemical properties at the cellular level.
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Affiliation(s)
- Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
| | - Silvia Sacchi
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
| | - Giulia Murtas
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
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12
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Montibeller L, de Belleroche J. Amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD) are characterised by differential activation of ER stress pathways: focus on UPR target genes. Cell Stress Chaperones 2018; 23:897-912. [PMID: 29725981 PMCID: PMC6111088 DOI: 10.1007/s12192-018-0897-y] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/06/2018] [Accepted: 04/08/2018] [Indexed: 12/11/2022] Open
Abstract
The endoplasmic reticulum (ER) plays an important role in maintenance of proteostasis through the unfolded protein response (UPR), which is strongly activated in most neurodegenerative disorders. UPR signalling pathways mediated by IRE1α and ATF6 play a crucial role in the maintenance of ER homeostasis through the transactivation of an array of transcription factors. When activated, these transcription factors induce the expression of genes involved in protein folding and degradation with pro-survival effects. However, the specific contribution of these transcription factors to different neurodegenerative diseases remains poorly defined. Here, we characterised 44 target genes strongly influenced by XBP1 and ATF6 and quantified the expression of a subset of genes in the human post-mortem spinal cord from amyotrophic lateral sclerosis (ALS) cases and in the frontal and temporal cortex from frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD) cases and controls. We found that IRE1α-XBP1 and ATF6 pathways were strongly activated both in ALS and AD. In ALS, XBP1 and ATF6 activation was confirmed by a substantial increase in the expression of both known and novel target genes involved particularly in co-chaperone activity and ER-associated degradation (ERAD) such as DNAJB9, SEL1L and OS9. In AD cases, a distinct pattern emerged, where targets involved in protein folding were more prominent, such as CANX, PDIA3 and PDIA6. These results reveal that both overlapping and disease-specific patterns of IRE1α-XBP1 and ATF6 target genes are activated in AD and ALS, which may be relevant to the development of new therapeutic strategies. Graphical abstract The endoplasmic reticulum (ER) plays an important role in maintenance of proteostasis through the unfolded protein response (UPR). Two major UPR signalling pathways are mediated by IRE1α and ATF6. Here, we demonstrate that these pathways activate differential gene sets in human post-mortem tissues derived from amyotrophic lateral sclerosis (ALS) compared to Alzheimer's disease (AD) cases. Our results identify IRE1α and ATF6 specific targets that can have major implications in the development of new therapeutic strategies and potential biomarkers.
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Affiliation(s)
- L Montibeller
- Neurogenetics Group, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - J de Belleroche
- Neurogenetics Group, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK.
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13
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Sacchi S, Cappelletti P, Murtas G. Biochemical Properties of Human D-amino Acid Oxidase Variants and Their Potential Significance in Pathologies. Front Mol Biosci 2018; 5:55. [PMID: 29946548 PMCID: PMC6005901 DOI: 10.3389/fmolb.2018.00055] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 05/23/2018] [Indexed: 12/11/2022] Open
Abstract
The stereoselective flavoenzyme D-amino acid oxidase (DAAO) catalyzes the oxidative deamination of neutral and polar D-amino acids producing the corresponding α-keto acids, ammonia, and hydrogen peroxide. Despite its peculiar and atypical substrates, DAAO is widespread expressed in most eukaryotic organisms. In mammals (and humans in particular), DAAO is involved in relevant physiological processes ranging from D-amino acid detoxification in kidney to neurotransmission in the central nervous system, where DAAO is responsible of the catabolism of D-serine, a key endogenous co-agonist of N-methyl-D-aspartate receptors. Recently, structural and functional studies have brought to the fore the distinctive biochemical properties of human DAAO (hDAAO). It appears to have evolved to allow a strict regulation of its activity, so that the enzyme can finely control the concentration of substrates (such as D-serine in the brain) without yielding to an excessive production of hydrogen peroxide, a potentially toxic reactive oxygen species (ROS). Indeed, dysregulation in D-serine metabolism, likely resulting from altered levels of hDAAO expression and activity, has been implicated in several pathologies, ranging from renal disease to neurological, neurodegenerative, and psychiatric disorders. Only one mutation in DAO gene was unequivocally associated to a human disease. However, several single nucleotide polymorphisms (SNPs) are reported in the database and the biochemical characterization of the corresponding recombinant hDAAO variants is of great interest for investigating the effect of mutations. Here we reviewed recently published data focusing on the modifications of the structural and functional properties induced by amino acid substitutions encoded by confirmed SNPs and on their effect on D-serine cellular levels. The potential significance of the different hDAAO variants in human pathologies will be also discussed.
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Affiliation(s)
- Silvia Sacchi
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy.,The Protein Factory, Politecnico di Milano and Università degli Studi dell'Insubria, Milan, Italy
| | - Pamela Cappelletti
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy.,The Protein Factory, Politecnico di Milano and Università degli Studi dell'Insubria, Milan, Italy
| | - Giulia Murtas
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
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14
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Distinctive Roles of D-Amino Acids in the Homochiral World: Chirality of Amino Acids Modulates Mammalian Physiology and Pathology. Keio J Med 2018; 68:1-16. [PMID: 29794368 DOI: 10.2302/kjm.2018-0001-ir] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Living organisms enantioselectively employ L-amino acids as the molecular architecture of protein synthesized in the ribosome. Although L-amino acids are dominantly utilized in most biological processes, accumulating evidence points to the distinctive roles of D-amino acids in non-ribosomal physiology. Among the three domains of life, bacteria have the greatest capacity to produce a wide variety of D-amino acids. In contrast, archaea and eukaryotes are thought generally to synthesize only two kinds of D-amino acids: D-serine and D-aspartate. In mammals, D-serine is critical for neurotransmission as an endogenous coagonist of N-methyl D-aspartate receptors. Additionally, D-aspartate is associated with neurogenesis and endocrine systems. Furthermore, recognition of D-amino acids originating in bacteria is linked to systemic and mucosal innate immunity. Among the roles played by D-amino acids in human pathology, the dysfunction of neurotransmission mediated by D-serine is implicated in psychiatric and neurological disorders. Non-enzymatic conversion of L-aspartate or L-serine residues to their D-configurations is involved in age-associated protein degeneration. Moreover, the measurement of plasma or urinary D-/L-serine or D-/L-aspartate levels may have diagnostic or prognostic value in the treatment of kidney diseases. This review aims to summarize current understanding of D-amino-acid-associated biology with a major focus on mammalian physiology and pathology.
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Kondori NR, Paul P, Robbins JP, Liu K, Hildyard JCW, Wells DJ, de Belleroche JS. Focus on the Role of D-serine and D-amino Acid Oxidase in Amyotrophic Lateral Sclerosis/Motor Neuron Disease (ALS). Front Mol Biosci 2018; 5:8. [PMID: 29487852 PMCID: PMC5816792 DOI: 10.3389/fmolb.2018.00008] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 01/19/2018] [Indexed: 12/11/2022] Open
Abstract
We have investigated a pathogenic mutation in D-amino acid oxidase (DAO), DAOR199W, associated with familial Amyotrophic Lateral Sclerosis (ALS) that impairs D-serine metabolism and causes protein aggregation, autophagy and cell death in motor neuron cell lines. These features are consistent with the pathogenic processes occurring in ALS but most importantly, we have demonstrated that activation of the formation of ubiquitinated protein inclusions, increased autophagosome production and apoptotic cell death caused by the mutation in cell lines are attenuated by 5,7-dichlorokynurenic acid (DCKA), a selective inhibitor of the glycine/D-serine binding site of the NMDA receptor. D-serine is an essential co-agonist at this glutamate receptor. This data provides insight into potential upstream mechanisms that involve the action of D-serine at the NMDA receptor and might contribute to neurodegeneration. This is highly relevant to sporadic ALS (SALS), familial ALS, as well as ALS models, where elevated levels of D-serine have been reported and hence has broader clinical therapeutic implications. In order to investigate this further, we have generated a transgenic line expressing the pathogenic mutation, in order to determine whether mice expressing DAOR199W develop a motor phenotype and whether crossing the SOD1G93A model of ALS with mice expressing DAOR199W affects disease progression. We found that heterozygous expression of DAOR199W led to a significant loss of spinal cord motor neurons at 14 months, which is similar to that found in homozygous mice expressing DAOG181R. We hypothesize that DAO has potential for development as a therapeutic agent in ALS.
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Affiliation(s)
- Nazanin R Kondori
- Neurogenetics Group, Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom.,Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Praveen Paul
- Neurogenetics Group, Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Jacqueline P Robbins
- Neurogenetics Group, Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Ke Liu
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - John C W Hildyard
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Dominic J Wells
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Jacqueline S de Belleroche
- Neurogenetics Group, Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
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Lin H, Hu H, Duan W, Liu Y, Tan G, Li Z, Liu Y, Deng B, Song X, Wang W, Wen D, Wang Y, Li C. Intramuscular Delivery of scAAV9-hIGF1 Prolongs Survival in the hSOD1 G93A ALS Mouse Model via Upregulation of D-Amino Acid Oxidase. Mol Neurobiol 2018; 55:682-695. [PMID: 27995572 DOI: 10.1007/s12035-016-0335-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/29/2016] [Indexed: 12/11/2022]
Abstract
Self-complementary adeno-associated viral vector 9 (scAAV9) has been confirmed to be an efficient AAV serotype for gene transfer to the central nervous system (CNS). Neurotrophic factors have been considered to be therapeutic targets for amyotrophic lateral sclerosis (ALS). In the present study, we intramuscularly injected scAAV9 encoding human insulin-like growth factor 1 (hIGF1) into an hSOD1G93A ALS mouse model. We observed that scAAV9-hIGF1 significantly reduced the loss of motor neurons of the anterior horn in the lumbar spinal cord and delayed muscle atrophy in ALS mice. Importantly, IGF1 significantly delayed disease onset and prolonged the life span of ALS mice. In addition, scAAV9-hIGF1 protected motor neurons from apoptosis through upregulation of D-amino acid oxidase (DAO), which controls the level of D-serine. Moreover, to further verify these results, we used CRISPR-Cas9 system to target the central nervous system knockdown of IGF1. This experiment supported the continued investigation of neurotrophic factor gene therapies targeting the central nervous system as a potential treatment for ALS.
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Affiliation(s)
- HuiQian Lin
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
- Department of Neurology, The First Hospital of Shijiazhuang City, Shijiazhuang, China
| | - HaoJie Hu
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - WeiSong Duan
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
- Key Laboratory of Hebei Neurology, Shijiazhuang, China
| | - YaLing Liu
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
- Key Laboratory of Hebei Neurology, Shijiazhuang, China
| | - GuoJun Tan
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
- Key Laboratory of Hebei Neurology, Shijiazhuang, China
| | - ZhongYao Li
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
- Key Laboratory of Hebei Neurology, Shijiazhuang, China
| | - YaKun Liu
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
- Key Laboratory of Hebei Neurology, Shijiazhuang, China
| | - BinBin Deng
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - XueQin Song
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
- Key Laboratory of Hebei Neurology, Shijiazhuang, China
| | - Wan Wang
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Di Wen
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Ying Wang
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - ChunYan Li
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China.
- Key Laboratory of Hebei Neurology, Shijiazhuang, China.
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Murtas G, Caldinelli L, Cappelletti P, Sacchi S, Pollegioni L. Human d-amino acid oxidase: The inactive G183R variant. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1866:822-830. [PMID: 29274788 DOI: 10.1016/j.bbapap.2017.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 12/12/2017] [Accepted: 12/14/2017] [Indexed: 12/11/2022]
Abstract
In the brain, the enzyme d-amino acid oxidase (DAAO) catalyzes the oxidative deamination of d-serine, a main positive modulator of the N-methyl-d-aspartate subtype of glutamate receptors (NMDAR). Dysregulation in d-serine signaling is implicated in the NMDAR dysfunctions observed in various brain diseases, such as amyotrophic lateral sclerosis, Alzheimer's disease, schizophrenia. A strain of ddY mice lacking DAAO activity due to the G181R substitution (DAAOG181R mice) and exhibiting increased d-serine concentration as compared to wild-type mice shows altered pain response, improved adaptative learning and cognitive functions, and larger hippocampal long-term potentiation. In past years, this mice line has been used to shed light on physiological and pathological brain functions related to NMDAR. Here, we decided to introduce the corresponding substitution in human DAAO (hDAAO). The recombinant G183R hDAAO is produced as an inactive apoprotein: the substitution alters the protein conformation that negatively affects the ability to bind the flavin cofactor in the orientation required for hydride-transfer during catalysis. At the cellular level, the overexpressed G183R hDAAO is not fully targeted to peroxisomes, forms protein aggregates showing a strong colocalization with ubiquitin, and significantly (7-fold) increases both the d-serine cellular concentration and the D/(D+L)-serine ratio. Taken together, our investigation warrants caution in using DAAOG181R mice: the abolition of enzymatic activity is coupled to DAAO aggregation, a central process in different pathological conditions. The effect due to G181R substitution in DAAO could be misleading: the effects due to impairment of d-serine degradation overlap with those related to aggregates accumulation.
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Affiliation(s)
- Giulia Murtas
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy.
| | - Laura Caldinelli
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano and Università degli studi dell'Insubria, via Mancinelli 7, 20131 Milan, Italy
| | - Pamela Cappelletti
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano and Università degli studi dell'Insubria, via Mancinelli 7, 20131 Milan, Italy
| | - Silvia Sacchi
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano and Università degli studi dell'Insubria, via Mancinelli 7, 20131 Milan, Italy
| | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano and Università degli studi dell'Insubria, via Mancinelli 7, 20131 Milan, Italy
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Kondori NR, Paul P, Robbins JP, Liu K, Hildyard JCW, Wells DJ, de Belleroche JS. Characterisation of the pathogenic effects of the in vivo expression of an ALS-linked mutation in D-amino acid oxidase: Phenotype and loss of spinal cord motor neurons. PLoS One 2017; 12:e0188912. [PMID: 29194436 PMCID: PMC5711026 DOI: 10.1371/journal.pone.0188912] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/15/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common adult-onset neuromuscular disorder characterised by selective loss of motor neurons leading to fatal paralysis. Current therapeutic approaches are limited in their effectiveness. Substantial advances in understanding ALS disease mechanisms has come from the identification of pathogenic mutations in dominantly inherited familial ALS (FALS). We previously reported a coding mutation in D-amino acid oxidase (DAOR199W) associated with FALS. DAO metabolises D-serine, an essential co-agonist at the N-Methyl-D-aspartic acid glutamate receptor subtype (NMDAR). Using primary motor neuron cultures or motor neuron cell lines we demonstrated that expression of DAOR199W, promoted the formation of ubiquitinated protein aggregates, activated autophagy and increased apoptosis. The aim of this study was to characterise the effects of DAOR199Win vivo, using transgenic mice overexpressing DAOR199W. Marked abnormal motor features, e.g. kyphosis, were evident in mice expressing DAOR199W, which were associated with a significant loss (19%) of lumbar spinal cord motor neurons, analysed at 14 months. When separated by gender, this effect was greater in females (26%; p< 0.0132). In addition, we crossed the DAOR199W transgenic mouse line with the SOD1G93A mouse model of ALS to determine whether the effects of SOD1G93A were potentiated in the double transgenic line (DAOR199W/SOD1G93A). Although overall survival was not affected, onset of neurological signs was significantly earlier in female double transgenic animals than their female SOD1G93A littermates (125 days vs 131 days, P = 0.0239). In summary, some significant in vivo effects of DAOR199W on motor neuron function (i.e. kyphosis and loss of motor neurons) were detected which were most marked in females and could contribute to the earlier onset of neurological signs in double transgenic females compared to SOD1G93A littermates, highlighting the importance of recognizing gender effects present in animal models of ALS.
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Affiliation(s)
- Nazanin Rahmani Kondori
- Neurogenetics Group, Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Praveen Paul
- Neurogenetics Group, Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Jacqueline P. Robbins
- Neurogenetics Group, Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Ke Liu
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - John C. W. Hildyard
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Dominic J. Wells
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Jacqueline S. de Belleroche
- Neurogenetics Group, Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
- * E-mail:
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Katane M, Kanazawa R, Kobayashi R, Oishi M, Nakayama K, Saitoh Y, Miyamoto T, Sekine M, Homma H. Structure-function relationships in human d-aspartate oxidase: characterisation of variants corresponding to known single nucleotide polymorphisms. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017. [PMID: 28629864 DOI: 10.1016/j.bbapap.2017.06.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
d-Aspartate oxidase (DDO) is a degradative enzyme that is stereospecific for the acidic amino acid d-aspartate, an endogenous agonist of the N-methyl-d-aspartate (NMDA) receptor. Dysregulation of NMDA receptor-mediated neurotransmission has been implicated in the onset of various neuropsychiatric disorders including schizophrenia and in chronic pain. Thus, appropriate regulation of the amount of d-aspartate is believed to be important for maintaining proper neural activity in the nervous system. Herein, the effects of the non-synonymous single nucleotide polymorphisms (SNPs) R216Q and S308N on several properties of human DDO were examined. Analysis of the purified recombinant enzyme showed that the R216Q and S308N substitutions reduce enzyme activity towards acidic d-amino acids, decrease the binding affinity for the coenzyme flavin adenine dinucleotide and decrease the temperature stability. Consistent with these findings, further experiments using cultured mammalian cells revealed elevated d-aspartate in cultures of R216Q and S308N cells compared with cells expressing wild-type DDO. Furthermore, accumulation of several amino acids other than d-aspartate also differed between these cultures. Thus, expression of DDO genes carrying the R216Q or S308N SNP substitutions may increase the d-aspartate content in humans and alter homeostasis of several other amino acids. This work may aid in understanding the correlation between DDO activity and the risk of onset of NMDA receptor-related diseases.
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Affiliation(s)
- Masumi Katane
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Ryo Kanazawa
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Risa Kobayashi
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Megumi Oishi
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Kazuki Nakayama
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Yasuaki Saitoh
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Tetsuya Miyamoto
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Masae Sekine
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Hiroshi Homma
- Laboratory of Biomolecular Science, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
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Acton D, Miles GB. Differential regulation of NMDA receptors by d-serine and glycine in mammalian spinal locomotor networks. J Neurophysiol 2017; 117:1877-1893. [PMID: 28202572 PMCID: PMC5411468 DOI: 10.1152/jn.00810.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/11/2017] [Accepted: 02/11/2017] [Indexed: 12/11/2022] Open
Abstract
We provide evidence that NMDARs within murine spinal locomotor networks determine the frequency and amplitude of ongoing locomotor-related activity in vitro and that NMDARs are regulated by d-serine and glycine in a synapse-specific and activity-dependent manner. In addition, glycine transporter-1 is shown to be an important regulator of NMDARs during locomotor-related activity. These results show how excitatory transmission can be tuned to diversify the output repertoire of spinal locomotor networks in mammals. Activation of N-methyl-d-aspartate receptors (NMDARs) requires the binding of a coagonist, either d-serine or glycine, in addition to glutamate. Changes in occupancy of the coagonist binding site are proposed to modulate neural networks including those controlling swimming in frog tadpoles. Here, we characterize regulation of the NMDAR coagonist binding site in mammalian spinal locomotor networks. Blockade of NMDARs by d(−)-2-amino-5-phosphonopentanoic acid (d-APV) or 5,7-dichlorokynurenic acid reduced the frequency and amplitude of pharmacologically induced locomotor-related activity recorded from the ventral roots of spinal-cord preparations from neonatal mice. Furthermore, d-APV abolished synchronous activity induced by blockade of inhibitory transmission. These results demonstrate an important role for NMDARs in murine locomotor networks. Bath-applied d-serine enhanced the frequency of locomotor-related but not disinhibited bursting, indicating that coagonist binding sites are saturated during the latter but not the former mode of activity. Depletion of endogenous d-serine by d-amino acid oxidase or the serine-racemase inhibitor erythro-β-hydroxy-l-aspartic acid (HOAsp) increased the frequency of locomotor-related activity, whereas application of l-serine to enhance endogenous d-serine synthesis reduced burst frequency, suggesting a requirement for d-serine at a subset of synapses onto inhibitory interneurons. Consistent with this, HOAsp was ineffective during disinhibited activity. Bath-applied glycine (1–100 µM) failed to alter locomotor-related activity, whereas ALX 5407, a selective inhibitor of glycine transporter-1 (GlyT1), enhanced burst frequency, supporting a role for GlyT1 in NMDAR regulation. Together these findings indicate activity-dependent and synapse-specific regulation of the coagonist binding site within spinal locomotor networks, illustrating the importance of NMDAR regulation in shaping motor output. NEW & NOTEWORTHY We provide evidence that NMDARs within murine spinal locomotor networks determine the frequency and amplitude of ongoing locomotor-related activity in vitro and that NMDARs are regulated by d-serine and glycine in a synapse-specific and activity-dependent manner. In addition, glycine transporter-1 is shown to be an important regulator of NMDARs during locomotor-related activity. These results show how excitatory transmission can be tuned to diversify the output repertoire of spinal locomotor networks in mammals.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
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Martinez FJ, Pratt GA, Van Nostrand EL, Batra R, Huelga SC, Kapeli K, Freese P, Chun SJ, Ling K, Gelboin-Burkhart C, Fijany L, Wang HC, Nussbacher JK, Broski SM, Kim HJ, Lardelli R, Sundararaman B, Donohue JP, Javaherian A, Lykke-Andersen J, Finkbeiner S, Bennett CF, Ares M, Burge CB, Taylor JP, Rigo F, Yeo GW. Protein-RNA Networks Regulated by Normal and ALS-Associated Mutant HNRNPA2B1 in the Nervous System. Neuron 2016; 92:780-795. [PMID: 27773581 DOI: 10.1016/j.neuron.2016.09.050] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/25/2016] [Accepted: 09/20/2016] [Indexed: 12/11/2022]
Abstract
HnRNPA2B1 encodes an RNA binding protein associated with neurodegeneration. However, its function in the nervous system is unclear. Transcriptome-wide crosslinking and immunoprecipitation in mouse spinal cord discover UAGG motifs enriched within ∼2,500 hnRNP A2/B1 binding sites and an unexpected role for hnRNP A2/B1 in alternative polyadenylation. HnRNP A2/B1 loss results in alternative splicing (AS), including skipping of an exon in amyotrophic lateral sclerosis (ALS)-associated D-amino acid oxidase (DAO) that reduces D-serine metabolism. ALS-associated hnRNP A2/B1 D290V mutant patient fibroblasts and motor neurons differentiated from induced pluripotent stem cells (iPSC-MNs) demonstrate abnormal splicing changes, likely due to increased nuclear-insoluble hnRNP A2/B1. Mutant iPSC-MNs display decreased survival in long-term culture and exhibit hnRNP A2/B1 localization to cytoplasmic granules as well as exacerbated changes in gene expression and splicing upon cellular stress. Our findings provide a cellular resource and reveal RNA networks relevant to neurodegeneration, regulated by normal and mutant hnRNP A2/B1. VIDEO ABSTRACT.
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Affiliation(s)
- Fernando J Martinez
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Gabriel A Pratt
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioinformatics and Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Eric L Van Nostrand
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ranjan Batra
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stephanie C Huelga
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Katannya Kapeli
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Peter Freese
- Department of Biology, MIT, Cambridge, MA 02139, USA
| | | | - Karen Ling
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA
| | - Chelsea Gelboin-Burkhart
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Layla Fijany
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Harrison C Wang
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Julia K Nussbacher
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sara M Broski
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Hong Joo Kim
- Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Rea Lardelli
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Balaji Sundararaman
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - John P Donohue
- Department of Molecular, Cell, and Developmental Biology, Sinsheimer Labs, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Ashkan Javaherian
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Jens Lykke-Andersen
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Steven Finkbeiner
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Departments of Neurology and Physiology, University of California, San Francisco, San Francisco, CA 94107, USA
| | | | - Manuel Ares
- Department of Molecular, Cell, and Developmental Biology, Sinsheimer Labs, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | | | - J Paul Taylor
- Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioinformatics and Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Molecular Engineering Laboratory, A(∗)STAR, Singapore 138673, Singapore.
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22
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Cappelletti P, Piubelli L, Murtas G, Caldinelli L, Valentino M, Molla G, Pollegioni L, Sacchi S. Structure-function relationships in human d-amino acid oxidase variants corresponding to known SNPs. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1150-9. [PMID: 25701391 DOI: 10.1016/j.bbapap.2015.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/05/2015] [Accepted: 02/07/2015] [Indexed: 12/11/2022]
Abstract
In the brain, d-amino acid oxidase plays a key role in modulating the N-methyl-d-aspartate receptor (NMDAR) activation state, catalyzing the stereospecific degradation of the coagonist d-serine. A relationship between d-serine signaling deregulation, NMDAR dysfunction, and CNS diseases is presumed. Notably, the R199W substitution in human DAAO (hDAAO) was associated with familial amyotrophic lateral sclerosis (ALS), and further coding substitutions, i.e., R199Q and W209R, were also deposited in the single nucleotide polymorphism database. Here, we investigated the biochemical properties of these different hDAAO variants. The W209R hDAAO variant shows an improved d-serine degradation ability (higher activity and affinity for the cofactor FAD) and produces a greater decrease in cellular d/(d+l) serine ratio than the wild-type counterpart when expressed in U87 cells. The production of H2O2 as result of excessive d-serine degradation by this hDAAO variant may represent the factor affecting cell viability after stable transfection. The R199W/Q substitution in hDAAO altered the protein conformation and enzymatic activity was lost under conditions resembling the cellular ones: this resulted in an abnormal increase in cellular d-serine levels. Altogether, these results indicate that substitutions that affect hDAAO functionality directly impact on d-serine cellular levels (at least in the model cell system used). The pathological effect of the expression of the R199W hDAAO, as observed in familial ALS, originates from both protein instability and a decrease in kinetic efficiency: the increase in synaptic d-serine may be mainly responsible for the neurotoxic effect. This information is expected to drive future targeted treatments.
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Affiliation(s)
- Pamela Cappelletti
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano, ICMR-CNR, Università degli Studi dell'Insubria, via Mancinelli 7, 20131 Milano, Italy
| | - Luciano Piubelli
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano, ICMR-CNR, Università degli Studi dell'Insubria, via Mancinelli 7, 20131 Milano, Italy
| | - Giulia Murtas
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy
| | - Laura Caldinelli
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano, ICMR-CNR, Università degli Studi dell'Insubria, via Mancinelli 7, 20131 Milano, Italy
| | - Mattia Valentino
- The Protein Factory, Politecnico di Milano, ICMR-CNR, Università degli Studi dell'Insubria, via Mancinelli 7, 20131 Milano, Italy; CNR, Istituto di Chimica del Riconoscimento Molecolare, Sezione Adolfo Quilico, via M. Bianchi 9, 20131 Milano, Italy
| | - Gianluca Molla
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano, ICMR-CNR, Università degli Studi dell'Insubria, via Mancinelli 7, 20131 Milano, Italy
| | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano, ICMR-CNR, Università degli Studi dell'Insubria, via Mancinelli 7, 20131 Milano, Italy
| | - Silvia Sacchi
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, via J. H. Dunant 3, 21100 Varese, Italy; The Protein Factory, Politecnico di Milano, ICMR-CNR, Università degli Studi dell'Insubria, via Mancinelli 7, 20131 Milano, Italy.
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23
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Experimental approaches for elucidating co-agonist regulation of NMDA receptor in motor neurons: Therapeutic implications for amyotrophic lateral sclerosis (ALS). J Pharm Biomed Anal 2015; 116:2-6. [PMID: 25604957 DOI: 10.1016/j.jpba.2014.12.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/18/2014] [Accepted: 12/23/2014] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neuromuscular disease characterised by selective loss of motor neurons leading to fatal paralysis. Although most cases are sporadic, approximately 10% of cases are familial and the identification of mutations in these kindred has greatly accelerated our understanding of disease mechanisms. To date, the causal genes in over 70% of these families have been identified. Recently, we reported a mutation (R199W) in the enzyme that degrades d-serine, D-amino acid oxidase (DAO) and co-segregates with disease in familial ALS. Moreover, D-serine and DAO are abundant in human spinal cord and severely depleted in ALS. Using cell culture models, we have defined the effects of R199W-DAO, and shown that it activates autophagy, leads to the formation of ubiquitinated protein aggregates and promotes apoptosis, all of which processes are attenuated by a D-serine/glycine site antagonist of the N-methyl D-aspartate receptor (NMDAR). These findings suggest that the toxic effects of R199W-DAO are at least in part mediated via the NMDAR involving the D-serine/glycine site and that an excitotoxic mechanism may contribute to disease pathogenesis.
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24
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Sasabe J, Suzuki M, Imanishi N, Aiso S. Activity of D-amino acid oxidase is widespread in the human central nervous system. Front Synaptic Neurosci 2014; 6:14. [PMID: 24959138 PMCID: PMC4050652 DOI: 10.3389/fnsyn.2014.00014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 05/20/2014] [Indexed: 12/11/2022] Open
Abstract
It has been proposed that D-amino acid oxidase (DAO) plays an essential role in degrading D-serine, an endogenous coagonist of N-methyl-D-aspartate (NMDA) glutamate receptors. DAO shows genetic association with amyotrophic lateral sclerosis (ALS) and schizophrenia, in whose pathophysiology aberrant metabolism of D-serine is implicated. Although the pathology of both essentially involves the forebrain, in rodents, enzymatic activity of DAO is hindbrain-shifted and absent in the region. Here, we show activity-based distribution of DAO in the central nervous system (CNS) of humans compared with that of mice. DAO activity in humans was generally higher than that in mice. In the human forebrain, DAO activity was distributed in the subcortical white matter and the posterior limb of internal capsule, while it was almost undetectable in those areas in mice. In the lower brain centers, DAO activity was detected in the gray and white matters in a coordinated fashion in both humans and mice. In humans, DAO activity was prominent along the corticospinal tract, rubrospinal tract, nigrostriatal system, ponto-/olivo-cerebellar fibers, and in the anterolateral system. In contrast, in mice, the reticulospinal tract and ponto-/olivo-cerebellar fibers were the major pathways showing strong DAO activity. In the human corticospinal tract, activity-based staining of DAO did not merge with a motoneuronal marker, but colocalized mostly with excitatory amino acid transporter 2 and in part with GFAP, suggesting that DAO activity-positive cells are astrocytes seen mainly in the motor pathway. These findings establish the distribution of DAO activity in cerebral white matter and the motor system in humans, providing evidence to support the involvement of DAO in schizophrenia and ALS. Our results raise further questions about the regulation of D-serine in DAO-rich regions as well as the physiological/pathological roles of DAO in white matter astrocytes.
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Affiliation(s)
- Jumpei Sasabe
- Department of Anatomy, Keio University School of Medicine Shinjuku-ku, Tokyo, Japan
| | - Masataka Suzuki
- Department of Anatomy, Keio University School of Medicine Shinjuku-ku, Tokyo, Japan
| | - Nobuaki Imanishi
- Department of Anatomy, Keio University School of Medicine Shinjuku-ku, Tokyo, Japan
| | - Sadakazu Aiso
- Department of Anatomy, Keio University School of Medicine Shinjuku-ku, Tokyo, Japan
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25
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Betts JF, Schweimer JV, Burnham KE, Burnet PWJ, Sharp T, Harrison PJ. D-amino acid oxidase is expressed in the ventral tegmental area and modulates cortical dopamine. Front Synaptic Neurosci 2014; 6:11. [PMID: 24822045 PMCID: PMC4014674 DOI: 10.3389/fnsyn.2014.00011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 04/09/2014] [Indexed: 12/11/2022] Open
Abstract
D-amino acid oxidase (DAO, DAAO) degrades the NMDA receptor co-agonist D-serine, modulating D-serine levels and thence NMDA receptor function. DAO inhibitors are under development as a therapy for schizophrenia, a disorder involving both NMDA receptor and dopaminergic dysfunction. However, a direct role for DAO in dopamine regulation has not been demonstrated. Here, we address this question in two ways. First, using in situ hybridization and immunohistochemistry, we show that DAO mRNA and immunoreactivity are present in the ventral tegmental area (VTA) of the rat, in tyrosine hydroxylase (TH)-positive and -negative neurons, and in glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes. Second, we show that injection into the VTA of sodium benzoate, a DAO inhibitor, increases frontal cortex extracellular dopamine, as measured by in vivo microdialysis and high performance liquid chromatography. Combining sodium benzoate and D-serine did not enhance this effect, and injection of D-serine alone affected dopamine metabolites but not dopamine. These data show that DAO is expressed in the VTA, and suggest that it impacts on the mesocortical dopamine system. The mechanism by which the observed effects occur, and the implications of these findings for schizophrenia therapy, require further study.
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Affiliation(s)
- Jill F Betts
- Department of Psychiatry, University of Oxford Oxford, UK ; Department of Pharmacology, University of Oxford Oxford, UK
| | - Judith V Schweimer
- Department of Psychiatry, University of Oxford Oxford, UK ; Department of Pharmacology, University of Oxford Oxford, UK
| | - Katherine E Burnham
- Department of Psychiatry, University of Oxford Oxford, UK ; Department of Pharmacology, University of Oxford Oxford, UK
| | | | - Trevor Sharp
- Department of Pharmacology, University of Oxford Oxford, UK
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26
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Paul P, de Belleroche J. The role of D-serine and glycine as co-agonists of NMDA receptors in motor neuron degeneration and amyotrophic lateral sclerosis (ALS). Front Synaptic Neurosci 2014; 6:10. [PMID: 24795623 PMCID: PMC3997022 DOI: 10.3389/fnsyn.2014.00010] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/29/2014] [Indexed: 12/11/2022] Open
Abstract
The fundamental role of D-serine as a co-agonist at the N-methyl-D-aspartate receptor (NMDAR), mediating both physiological actions of glutamate in long term potentiation and nociception and also pathological effects mediated by excitotoxicty, are well-established. More recently, a direct link to a chronic neurodegenerative disease, amyotrophic lateral sclerosis/motor neuron disease (ALS) has been suggested by findings that D-serine levels are elevated in sporadic ALS and the G93A SOD1 model of ALS (Sasabe et al., 2007, 2012) and that a pathogenic mutation (R199W) in the enzyme that degrades D-serine, D-amino acid oxidase (DAO), co-segregates with disease in familial ALS (Mitchell et al., 2010). Moreover, D-serine, its biosynthetic enzyme, serine racemase (SR) and DAO are abundant in human spinal cord and severely depleted in ALS. Using cell culture models, we have defined the effects of R199W-DAO, and shown that it activates autophagy, leads to the formation of ubiquitinated aggregates and promotes apoptosis, all of which processes are attenuated by a D-serine/glycine site NMDAR antagonist. These studies provide considerable insight into the crosstalk between neurons and glia and also into potential therapeutic approaches for ALS.
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Affiliation(s)
- Praveen Paul
- Neurogenetics Group, Division of Brain Sciences, Department of Medicine, Imperial College London London, UK
| | - Jackie de Belleroche
- Neurogenetics Group, Division of Brain Sciences, Department of Medicine, Imperial College London London, UK
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