1
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Rabattoni V, Motta Z, Miceli M, Molla G, Fissore A, Adinolfi S, Pollegioni L, Sacchi S. On the regulation of human D-aspartate oxidase. Protein Sci 2023; 32:e4802. [PMID: 37805834 PMCID: PMC10588558 DOI: 10.1002/pro.4802] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 09/14/2023] [Accepted: 10/03/2023] [Indexed: 10/09/2023]
Abstract
The human flavoenzyme D-aspartate oxidase (hDASPO) controls the level of D-aspartate in the brain, a molecule acting as an agonist of NMDA receptors and modulator of AMPA and mGlu5 receptors. hDASPO-induced D-aspartate degradation prevents age-dependent deterioration of brain functions and is related to psychiatric disorders such as schizophrenia and autism. Notwithstanding this crucial role, less is known about hDASPO regulation. Here, we report that hDASPO is nitrosylated in vitro, while no evidence of sulfhydration and phosphorylation is apparent: nitrosylation affects the activity of the human flavoenzyme to a limited extent. Furthermore, hDASPO interacts with the primate-specific protein pLG72 (a well-known negative chaperone of D-amino acid oxidase, the enzyme deputed to D-serine degradation in the human brain), yielding a ~114 kDa complex, with a micromolar dissociation constant, promoting the flavoenzyme inactivation. At the cellular level, pLG72 and hDASPO generate a cytosolic complex: the expression of pLG72 negatively affects the hDASPO level by reducing its half-life. We propose that pLG72 binding may represent a protective mechanism aimed at avoiding cytotoxicity due to H2 O2 produced by the hDASPO enzymatic degradation of D-aspartate, especially before the final targeting to peroxisomes.
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Affiliation(s)
- Valentina Rabattoni
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Zoraide Motta
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Matteo Miceli
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Gianluca Molla
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Alex Fissore
- Dipartimento di Scienza e Tecnologia del FarmacoUniversità di TorinoTorinoItaly
| | - Salvatore Adinolfi
- Dipartimento di Scienza e Tecnologia del FarmacoUniversità di TorinoTorinoItaly
| | - Loredano Pollegioni
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Silvia Sacchi
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
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2
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Murtas G, Pollegioni L, Molla G, Sacchi S. Biochemical Properties and Physiological Functions of pLG72: Twenty Years of Investigations. Biomolecules 2022; 12:biom12060858. [PMID: 35740983 PMCID: PMC9220908 DOI: 10.3390/biom12060858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/13/2022] [Accepted: 06/18/2022] [Indexed: 11/16/2022] Open
Abstract
In 2002, the novel human gene G72 was associated with schizophrenia susceptibility. This gene encodes a small protein of 153 amino acids, named pLG72, which represents a rare case of primate-specific protein. In particular, the rs2391191 single nucleotide polymorphism (resulting in in the R30K substitution) was robustly associated to schizophrenia and bipolar disorder. In this review, we aim to summarize the results of 20 years of biochemical investigations on pLG72. The main known role of pLG72 is related to its ability to bind and inactivate the flavoenzyme d-amino acid oxidase, i.e., the enzyme that controls the catabolism of d-serine, the main NMDA receptor coagonist in the brain. pLG72 was proposed to target the cytosolic form of d-amino acid oxidase for degradation, preserving d-serine and protecting the cell from oxidative stress generated by hydrogen peroxide produced by the flavoenzyme reaction. Anyway, pLG72 seems to play additional roles, such as affecting mitochondrial functions. The level of pLG72 in the human body is still a controversial issue because of its low expression and challenging detection. Anyway, the intriguing hypothesis that pLG72 level in blood could represent a suitable marker of Alzheimer’s disease progression (a suggestion not sufficiently established yet) merits further investigations.
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3
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Wang J, Serratrice N, Lee CJ, François F, Sweedler JV, Puel JL, Mothet JP, Ruel J. Physiopathological Relevance of D-Serine in the Mammalian Cochlea. Front Cell Neurosci 2022; 15:733004. [PMID: 34975405 PMCID: PMC8718999 DOI: 10.3389/fncel.2021.733004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 11/29/2021] [Indexed: 12/02/2022] Open
Abstract
NMDA receptors (NMDARs) populate the complex between inner hair cell (IHC) and spiral ganglion neurons (SGNs) in the developing and mature cochlea. However, in the mature cochlea, activation of NMDARs is thought to mainly occur under pathological conditions such as excitotoxicity. Ototoxic drugs such as aspirin enable cochlear arachidonic-acid-sensitive NMDAR responses, and induced chronic tinnitus was blocked by local application of NMDAR antagonists into the cochlear fluids. We largely ignore if other modulators are also engaged. In the brain, D-serine is the primary physiological co-agonist of synaptic NMDARs. Whether D-serine plays a role in the cochlea had remained unexplored. We now reveal the presence of D-serine and its metabolic enzymes prior to, and at hearing onset, in the sensory and non-neuronal cells of the cochlea of several vertebrate species. In vivo intracochlear perfusion of D-serine in guinea pigs reduces sound-evoked activity of auditory nerve fibers without affecting the receptor potentials, suggesting that D-serine acts specifically on the postsynaptic auditory neurons without altering the functional state of IHC or of the stria vascularis. Indeed, we demonstrate in vitro that agonist-induced activation of NMDARs produces robust calcium responses in rat SGN somata only in the presence of D-serine, but not of glycine. Surprisingly, genetic deletion in mice of serine racemase (SR), the enzyme that catalyzes D-serine, does not affect hearing function, but offers protection against noise-induced permanent hearing loss as measured 3 months after exposure. However, the mechanisms of activation of NMDA receptors in newborn rats may be different from those in adult guinea pigs. Taken together, these results demonstrate for the first time that the neuro-messenger D-serine has a pivotal role in the cochlea by promoting the activation of silent cochlear NMDAR in pathological situations. Thus, D-serine and its signaling pathway may represent a new druggable target for treating sensorineural hearing disorders (i.e., hearing loss, tinnitus).
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Affiliation(s)
- Jing Wang
- Institute for Neurosciences of Montpellier (INM), University Montpellier, Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France.,ENT Department, Hospital and University of Montpellier, Montpellier, France
| | - Nicolas Serratrice
- Institute for Neurosciences of Montpellier (INM), University Montpellier, Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France
| | - Cindy J Lee
- Department of Chemistry, Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Florence François
- Institute for Neurosciences of Montpellier (INM), University Montpellier, Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France
| | - Jonathan V Sweedler
- Department of Chemistry, Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France
| | - Jean-Pierre Mothet
- Laboratoire LuMin, Biophotonics and Synapse Physiopathology Team, Université Paris-Saclay, Centre National de la Recherche Scientifique (CNRS), ENS Paris Saclay, Centrale Supélec, Gif-sur-Yvette, France
| | - Jérôme Ruel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France.,Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Laboratoire de Neurosciences Cognitives, Marseille, France
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4
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d-Amino Acids and pLG72 in Alzheimer's Disease and Schizophrenia. Int J Mol Sci 2021; 22:ijms222010917. [PMID: 34681579 PMCID: PMC8535920 DOI: 10.3390/ijms222010917] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/01/2021] [Accepted: 10/06/2021] [Indexed: 01/02/2023] Open
Abstract
Numerous studies over the last several years have shown that d-amino acids, especially d-serine, have been related to brain and neurological disorders. Acknowledged neurological functions of d-amino acids include neurotransmission and learning and memory functions through modulating N-methyl-d-aspartate type glutamate receptors (NMDARs). Aberrant d-amino acids level and polymorphisms of genes related to d-amino acids metabolism are associated with neurodegenerative brain conditions. This review summarizes the roles of d-amino acids and pLG72, also known as d-amino acid oxidase activator, on two neurodegenerative disorders, schizophrenia and Alzheimer’s disease (AD). The scope includes the changes in d-amino acids levels, gene polymorphisms of G72 genomics, and the role of pLG72 on NMDARs and mitochondria in schizophrenia and AD. The clinical diagnostic value of d-amino acids and pLG72 and the therapeutic importance are also reviewed.
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5
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Piubelli L, Murtas G, Rabattoni V, Pollegioni L. The Role of D-Amino Acids in Alzheimer's Disease. J Alzheimers Dis 2021; 80:475-492. [PMID: 33554911 DOI: 10.3233/jad-201217] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD), the main cause of dementia worldwide, is characterized by a complex and multifactorial etiology. In large part, excitatory neurotransmission in the central nervous system is mediated by glutamate and its receptors are involved in synaptic plasticity. The N-methyl-D-aspartate (NMDA) receptors, which require the agonist glutamate and a coagonist such as glycine or the D-enantiomer of serine for activation, play a main role here. A second D-amino acid, D-aspartate, acts as agonist of NMDA receptors. D-amino acids, present in low amounts in nature and long considered to be of bacterial origin, have distinctive functions in mammals. In recent years, alterations in physiological levels of various D-amino acids have been linked to various pathological states, ranging from chronic kidney disease to neurological disorders. Actually, the level of NMDA receptor signaling must be balanced to promote neuronal survival and prevent neurodegeneration: this signaling in AD is affected mainly by glutamate availability and modulation of the receptor's functions. Here, we report the experimental findings linking D-serine and D-aspartate, through NMDA receptor modulation, to AD and cognitive functions. Interestingly, AD progression has been also associated with the enzymes related to D-amino acid metabolism as well as with glucose and serine metabolism. Furthermore, the D-serine and D-/total serine ratio in serum have been recently proposed as biomarkers of AD progression. A greater understanding of the role of D-amino acids in excitotoxicity related to the pathogenesis of AD will facilitate novel therapeutic treatments to cure the disease and improve life expectancy.
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Affiliation(s)
- Luciano Piubelli
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Giulia Murtas
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Valentina Rabattoni
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Loredano Pollegioni
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
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6
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Pei JC, Luo DZ, Gau SS, Chang CY, Lai WS. Directly and Indirectly Targeting the Glycine Modulatory Site to Modulate NMDA Receptor Function to Address Unmet Medical Needs of Patients With Schizophrenia. Front Psychiatry 2021; 12:742058. [PMID: 34658976 PMCID: PMC8517243 DOI: 10.3389/fpsyt.2021.742058] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 09/02/2021] [Indexed: 12/30/2022] Open
Abstract
Schizophrenia is a severe mental illness that affects ~1% of the world's population. It is clinically characterized by positive, negative, and cognitive symptoms. Currently available antipsychotic medications are relatively ineffective in improving negative and cognitive deficits, which are related to a patient's functional outcomes and quality of life. Negative symptoms and cognitive deficits are unmet by the antipsychotic medications developed to date. In recent decades, compelling animal and clinical studies have supported the NMDA receptor (NMDAR) hypofunction hypothesis of schizophrenia and have suggested some promising therapeutic agents. Notably, several NMDAR-enhancing agents, especially those that function through the glycine modulatory site (GMS) of NMDAR, cause significant reduction in psychotic and cognitive symptoms in patients with schizophrenia. Given that the NMDAR-mediated signaling pathway has been implicated in cognitive/social functions and that GMS is a potential therapeutic target for enhancing the activation of NMDARs, there is great interest in investigating the effects of direct and indirect GMS modulators and their therapeutic potential. In this review, we focus on describing preclinical and clinical studies of direct and indirect GMS modulators in the treatment of schizophrenia, including glycine, D-cycloserine, D-serine, glycine transporter 1 (GlyT1) inhibitors, and D-amino acid oxidase (DAO or DAAO) inhibitors. We highlight some of the most promising recently developed pharmacological compounds designed to either directly or indirectly target GMS and thus augment NMDAR function to treat the cognitive and negative symptoms of schizophrenia. Overall, the current findings suggest that indirectly targeting of GMS appears to be more beneficial and leads to less adverse effects than direct targeting of GMS to modulate NMDAR functions. Indirect GMS modulators, especially GlyT1 inhibitors and DAO inhibitors, open new avenues for the treatment of unmet medical needs for patients with schizophrenia.
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Affiliation(s)
- Ju-Chun Pei
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Da-Zhong Luo
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Shiang-Shin Gau
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Chia-Yuan Chang
- Department of Psychology, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
| | - Wen-Sung Lai
- Department of Psychology, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
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7
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Takagi S, Balu DT, Coyle JT. Factors regulating serine racemase and d-amino acid oxidase expression in the mouse striatum. Brain Res 2020; 1751:147202. [PMID: 33171153 DOI: 10.1016/j.brainres.2020.147202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/23/2020] [Accepted: 11/03/2020] [Indexed: 10/23/2022]
Abstract
d-Serine plays an important role in modulating N-methyl-d-aspartate receptor (NMDAR) neurotransmission in the mammalian brain by binding to the receptor's glycine modulatory site (GMS). The cytosolic enzyme serine racemase (SR) converts L-serine to d-serine, while the peroxisomal enzyme d-amino acid oxidase (DAAO) catalyzes the breakdown of d-serine. Although it is important to understand how the activities of SR and DAAO regulate d-serine levels, very little is known about the mechanisms that regulate the expression of SR and DAAO. In this study, we investigated whether the different centrally active drugs affect the expression of SR and DAAO in adult mouse brain. We found that the NMDAR antagonist, MK801, and cocaine, psychotropic drugs that both augment glutamate release, reduce the expression of SR and DAAO. This regulation is brain region selective, and in the case of cocaine, is reversed in part byα-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX). However, d-serine and antipsychotics do not regulate SR and DAAO protein levels. In a genetic model of SR disruption, we found that DAAO expression was unaltered in SR conditional knockout mice, in which tissue d-serine content remains fairly stable despite marked reduction in SR expression. This study reveals a new mechanism by which AMPAR activity could regulate NMDAR function via d-serine availability.
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Affiliation(s)
- Shunsuke Takagi
- Department of Psychiatry and Behavioral Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA 02478, USA.
| | - Darrick T Balu
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115, USA; Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA 02478, USA
| | - Joseph T Coyle
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115, USA; Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA 02478, USA
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8
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Lin CH, Chiu CC, Huang CH, Yang HT, Lane HY. pLG72 levels increase in early phase of Alzheimer's disease but decrease in late phase. Sci Rep 2019; 9:13221. [PMID: 31520071 PMCID: PMC6744481 DOI: 10.1038/s41598-019-49522-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 08/22/2019] [Indexed: 12/17/2022] Open
Abstract
pLG72, named as D-amino acid oxidase activator (although it is not an activator of D-amino acid oxidase demonstrated by later studies), in mitochondria has been regarded as an important modulator of D-amino acid oxidase that can regulate the N-methyl-D-aspartate receptor (NMDAR). Both oxidative stress in mitochondria and NMDAR neurotransmission play essential roles in the process of neurodegenerative dementia. The aim of the study was to investigate whether pLG72 levels changed with the severity of neurodegenerative dementia. We enrolled 376 individuals as the overall cohort, consisting of five groups: healthy elderly, amnestic mild cognitive impairment [MCI], mild Alzheimer's disease [AD], moderate AD, and severe AD. pLG72 levels in plasma were measured using Western blotting. The severity of cognitive deficit was principally evaluated by Clinical Dementia Rating Scale. A gender- and age- matched cohort was selected to elucidate the effects of gender and age. pLG72 levels increased in the MCI and mild AD groups when compared to the healthy group. However, pLG72 levels in the moderate and severe AD groups were lower than those in the mild AD group. D-serine level and D- to total serine ratio were significantly different among the five groups. L-serine levels were correlated with the pLG72 levels. The results in the gender- and age- matched cohort were similar to those of the overall cohort. The finding supports the hypothesis of NMDAR hypofunction in early-phase dementia and NMDAR hyperfunction in late-phase dementia. Further studies are warranted to test whether pLG72 could reflect the function of NMDAR.
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Affiliation(s)
- Chieh-Hsin Lin
- Department of Psychiatry, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
- School of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chih-Chiang Chiu
- Department of Psychiatry, Taipei City Psychiatric Center, Taipei, Taiwan
- Department of Psychiatry, School of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chiung-Hsien Huang
- Department of Medicine Research, China Medical University Hospital, Taichung, Taiwan
| | - Hui-Ting Yang
- Department of Psychiatry, School of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Hsien-Yuan Lane
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.
- Department of Psychiatry & Brain Disease Research Center, China Medical University Hospital, Taichung, Taiwan.
- Department of Psychology, College of Medical and Health Sciences, Asia University, Taichung, Taiwan.
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9
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MacKay MAB, Kravtsenyuk M, Thomas R, Mitchell ND, Dursun SM, Baker GB. D-Serine: Potential Therapeutic Agent and/or Biomarker in Schizophrenia and Depression? Front Psychiatry 2019; 10:25. [PMID: 30787885 PMCID: PMC6372501 DOI: 10.3389/fpsyt.2019.00025] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 01/15/2019] [Indexed: 11/17/2022] Open
Abstract
D-Serine is a potent co-agonist at the NMDA glutamate receptor and has been the object of many preclinical studies to ascertain the nature of its metabolism, its regional and cellular distribution in the brain, its physiological functions and its possible clinical relevance. The enzymes involved in its formation and catabolism are serine racemase (SR) and D-amino acid oxidase (DAAO), respectively, and manipulations of the activity of those enzymes have been useful in developing animal models of schizophrenia and in providing clues to the development of potential new antipsychotic strategies. Clinical studies have been conducted in schizophrenia patients to evaluate body fluid levels of D-serine and/or to use D-serine alone or in combination with antipsychotics to determine its effectiveness as a therapeutic agent. D-serine has also been used in combination with DAAO inhibitors in preclinical investigations, and interesting results have been obtained. Genetic studies and postmortem brain studies have also been conducted on D-serine and the enzymes involved in its metabolism. It is also of considerable interest that in recent years clinical and preclinical investigations have suggested that D-serine may also have antidepressant properties. Clinical studies have also shown that D-serine may be a biomarker for antidepressant response to ketamine. Relevant to both schizophrenia and depression, preclinical and clinical studies with D-serine indicate that it may be effective in reducing cognitive dysfunction.
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Affiliation(s)
- Mary-Anne B MacKay
- Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Maryana Kravtsenyuk
- Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Rejish Thomas
- Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Nicholas D Mitchell
- Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Serdar M Dursun
- Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Glen B Baker
- Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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10
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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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11
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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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