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Katane M, Homma H. Biosynthesis and Degradation of Free D-Amino Acids and Their Physiological Roles in the Periphery and Endocrine Glands. Biol Pharm Bull 2024; 47:562-579. [PMID: 38432912 DOI: 10.1248/bpb.b23-00485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
It was long believed that D-amino acids were either unnatural isomers or laboratory artifacts, and that the important functions of amino acids were exerted only by L-amino acids. However, recent investigations have revealed a variety of D-amino acids in mammals that play important roles in physiological functions, including free D-serine and D-aspartate that are crucial in the central nervous system. The functions of several D-amino acids in the periphery and endocrine glands are also receiving increasing attention. Here, we present an overview of recent advances in elucidating the physiological roles of D-amino acids, especially in the periphery and endocrine glands.
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Affiliation(s)
- Masumi Katane
- Medicinal Research Laboratories, Graduate School of Pharmaceutical Sciences, Kitasato University
| | - Hiroshi Homma
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University
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Santillo A, Falvo S, Venditti M, Di Maio A, Chieffi Baccari G, Errico F, Usiello A, Minucci S, Di Fiore MM. D-Aspartate Depletion Perturbs Steroidogenesis and Spermatogenesis in Mice. Biomolecules 2023; 13:biom13040621. [PMID: 37189369 DOI: 10.3390/biom13040621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/23/2023] [Accepted: 03/28/2023] [Indexed: 04/01/2023] Open
Abstract
High levels of free D-aspartate (D-Asp) are present in vertebrate testis during post-natal development, coinciding with the onset of testosterone production, which suggests that this atypical amino acid might participate in the regulation of hormone biosynthesis. To elucidate the unknown role of D-Asp on testicular function, we investigated steroidogenesis and spermatogenesis in a one-month-old knockin mouse model with the constitutive depletion of D-Asp levels due to the targeted overexpression of D-aspartate oxidase (DDO), which catalyzes the deaminative oxidation of D-Asp to generate the corresponding α-keto acid, oxaloacetate, hydrogen peroxide, and ammonium ions. In the Ddo knockin mice, we found a dramatic reduction in testicular D-Asp levels, accompanied by a significant decrease in the serum testosterone levels and testicular 17β-HSD, the enzyme involved in testosterone biosynthesis. Additionally, in the testes of these Ddo knockin mice, the expression of PCNA and SYCP3 proteins decreased, suggesting alterations in spermatogenesis-related processes, as well as an increase in the cytosolic cytochrome c protein levels and TUNEL-positive cell number, which indicate an increase in apoptosis. To further investigate the histological and morphometric testicular alterations in Ddo knockin mice, we analyzed the expression and localization of prolyl endopeptidase (PREP) and disheveled-associated activator of morphogenesis 1 (DAAM1), two proteins involved in cytoskeletal organization. Our results showed that the testicular levels of DAAM1 and PREP in Ddo knockin mice were different from those in wild-type animals, suggesting that the deficiency of D-Asp is associated with overall cytoskeletal disorganization. Our findings confirmed that physiological D-Asp influences testosterone biosynthesis and plays a crucial role in germ cell proliferation and differentiation, which are required for successful reproduction.
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Machine Learning algorithm unveils glutamatergic alterations in the post-mortem schizophrenia brain. NPJ SCHIZOPHRENIA 2022; 8:8. [PMID: 35217646 PMCID: PMC8881508 DOI: 10.1038/s41537-022-00231-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 12/06/2021] [Indexed: 01/24/2023]
Abstract
Schizophrenia is a disorder of synaptic plasticity and aberrant connectivity in which a major dysfunction in glutamate synapse has been suggested. However, a multi-level approach tackling diverse clusters of interacting molecules of the glutamate signaling in schizophrenia is still lacking. We investigated in the post-mortem dorsolateral prefrontal cortex (DLPFC) and hippocampus of schizophrenia patients and non-psychiatric controls, the levels of neuroactive d- and l-amino acids (l-glutamate, d-serine, glycine, l-aspartate, d-aspartate) by HPLC. Moreover, by quantitative RT-PCR and western blotting we analyzed, respectively, the mRNA and protein levels of pre- and post-synaptic key molecules involved in the glutamatergic synapse functioning, including glutamate receptors (NMDA, AMPA, metabotropic), their interacting scaffolding proteins (PSD-95, Homer1b/c), plasma membrane and vesicular glutamate transporters (EAAT1, EAAT2, VGluT1, VGluT2), enzymes involved either in glutamate-dependent GABA neurotransmitter synthesis (GAD65 and 67), or in post-synaptic NMDA receptor-mediated signaling (CAMKIIα) and the pre-synaptic marker Synapsin-1. Univariable analyses revealed that none of the investigated molecules was differently represented in the post-mortem DLPFC and hippocampus of schizophrenia patients, compared with controls. Nonetheless, multivariable hypothesis-driven analyses revealed that the presence of schizophrenia was significantly affected by variations in neuroactive amino acid levels and glutamate-related synaptic elements. Furthermore, a Machine Learning hypothesis-free unveiled other discriminative clusters of molecules, one in the DLPFC and another in the hippocampus. Overall, while confirming a key role of glutamatergic synapse in the molecular pathophysiology of schizophrenia, we reported molecular signatures encompassing elements of the glutamate synapse able to discriminate patients with schizophrenia and normal individuals.
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Katane M, Matsuda S, Saitoh Y, Miyamoto T, Sekine M, Sakai-Kato K, Homma H. Glyoxylate reductase/hydroxypyruvate reductase regulates the free d-aspartate level in mammalian cells. J Cell Biochem 2021; 122:1639-1652. [PMID: 34289161 DOI: 10.1002/jcb.30110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/30/2021] [Accepted: 07/09/2021] [Indexed: 12/16/2022]
Abstract
Multiple d-amino acids are present in mammalian cells, and these compounds have distinctive physiological functions. Among the free d-amino acids identified in mammals, d-aspartate plays critical roles in the neuroendocrine and endocrine systems, as well as in the central nervous system. Mammalian cells have the molecular apparatus necessary to take up, degrade, synthesize, and release d-aspartate. In particular, d-aspartate is degraded by d-aspartate oxidase (DDO), a peroxisome-localized enzyme that catalyzes the oxidative deamination of d-aspartate to generate oxaloacetate, hydrogen peroxide, and ammonia. However, little is known about the molecular mechanisms underlying d-aspartate homeostasis in cells. In this study, we established a cell line that overexpresses cytoplasm-localized DDO; this cell line cannot survive in the presence of high concentrations of d-aspartate, presumably because high levels of toxic hydrogen peroxide are produced by metabolism of abundant d-aspartate by DDO in the cytoplasm, where hydrogen peroxide cannot be removed due to the absence of catalase. Next, we transfected these cells with a complementary DNA library derived from the human brain and screened for clones that affected d-aspartate metabolism and improved cell survival, even when the cells were challenged with high concentrations of d-aspartate. The screen identified a clone of glyoxylate reductase/hydroxypyruvate reductase (GRHPR). Moreover, the GRHPR metabolites glyoxylate and hydroxypyruvate inhibited the enzymatic activity of DDO. Furthermore, we evaluated the effects of GRHPR and peroxisome-localized DDO on d- and l-aspartate levels in cultured mammalian cells. Our findings show that GRHPR contributes to the homeostasis of these amino acids in mammalian cells.
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Affiliation(s)
- Masumi Katane
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
| | - Satsuki Matsuda
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
| | - Yasuaki Saitoh
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
| | - Tetsuya Miyamoto
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
| | - Masae Sekine
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
| | - Kumiko Sakai-Kato
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
| | - Hiroshi Homma
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo, Japan
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Pollegioni L, Molla G, Sacchi S, Murtas G. Human D-aspartate Oxidase: A Key Player in D-aspartate Metabolism. Front Mol Biosci 2021; 8:689719. [PMID: 34250021 PMCID: PMC8260693 DOI: 10.3389/fmolb.2021.689719] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/09/2021] [Indexed: 11/15/2022] Open
Abstract
In recent years, the D-enantiomers of amino acids have been recognized as natural molecules present in all kingdoms, playing a variety of biological roles. In humans, d-serine and d-aspartate attracted attention for their presence in the central nervous system. Here, we focus on d-aspartate, which is involved in glutamatergic neurotransmission and the synthesis of various hormones. The biosynthesis of d-aspartate is still obscure, while its degradation is due to the peroxisomal flavin adenine dinucleotide (FAD)-containing enzyme d-aspartate oxidase. d-Aspartate emergence is strictly controlled: levels decrease in brain within the first days of life while increasing in endocrine glands postnatally and through adulthood. The human d-aspartate oxidase (hDASPO) belongs to the d-amino acid oxidase-like family: its tertiary structure closely resembles that of human d-amino acid oxidase (hDAAO), the enzyme that degrades neutral and basic d-amino acids. The structure-function relationships of the physiological isoform of hDASPO (named hDASPO_341) and the regulation of gene expression and distribution and properties of the longer isoform hDASPO_369 have all been recently elucidated. Beyond the substrate preference, hDASPO and hDAAO also differ in kinetic efficiency, FAD-binding affinity, pH profile, and oligomeric state. Such differences suggest that evolution diverged to create two different ways to modulate d-aspartate and d-serine levels in the human brain. Current knowledge about hDASPO is shedding light on the molecular mechanisms underlying the modulation of d-aspartate levels in human tissues and is pushing novel, targeted therapeutic strategies. Now, it has been proposed that dysfunction in NMDA receptor-mediated neurotransmission is caused by disrupted d-aspartate metabolism in the nervous system during the onset of various disorders (such as schizophrenia): the design of suitable hDASPO inhibitors aimed at increasing d-aspartate levels thus represents a novel and useful form of therapy.
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Affiliation(s)
- Loredano Pollegioni
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Gianluca Molla
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Silvia Sacchi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Giulia Murtas
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
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Identification of an l-serine/l-threonine dehydratase with glutamate racemase activity in mammals. Biochem J 2020; 477:4221-4241. [DOI: 10.1042/bcj20200721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 10/12/2020] [Accepted: 10/20/2020] [Indexed: 02/02/2023]
Abstract
Recent investigations have shown that multiple d-amino acids are present in mammals and these compounds have distinctive physiological functions. Free d-glutamate is present in various mammalian tissues and cells and in particular, it is presumably correlated with cardiac function, and much interest is growing in its unique metabolic pathways. Recently, we first identified d-glutamate cyclase as its degradative enzyme in mammals, whereas its biosynthetic pathway in mammals is unclear. Glutamate racemase is a most probable candidate, which catalyzes interconversion between d-glutamate and l-glutamate. Here, we identified the cDNA encoding l-serine dehydratase-like (SDHL) as the first mammalian clone with glutamate racemase activity. This rat SDHL had been deposited in mammalian databases as a protein of unknown function and its amino acid sequence shares ∼60% identity with that of l-serine dehydratase. Rat SDHL was expressed in Escherichia coli, and the enzymatic properties of the recombinant were characterized. The results indicated that rat SDHL is a multifunctional enzyme with glutamate racemase activity in addition to l-serine/l-threonine dehydratase activity. This clone is hence abbreviated as STDHgr. Further experiments using cultured mammalian cells confirmed that d-glutamate was synthesized and l-serine and l-threonine were decomposed. It was also found that SDHL (STDHgr) contributes to the homeostasis of several other amino acids.
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Nuzzo T, Miroballo M, Casamassa A, Mancini A, Gaetani L, Nisticò R, Eusebi P, Katane M, Homma H, Calabresi P, Errico F, Parnetti L, Usiello A. Cerebrospinal fluid and serum d-serine concentrations are unaltered across the whole clinical spectrum of Alzheimer's disease. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140537. [PMID: 32896673 DOI: 10.1016/j.bbapap.2020.140537] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 08/26/2020] [Accepted: 09/01/2020] [Indexed: 12/16/2022]
Abstract
The diagnosis of Alzheimer's disease (AD) relies on the presence of amyloidosis and tauopathy, as reflected in cerebrospinal fluid (CSF), independently from the clinical stage. Recently, CSF d-serine has been proposed as a possible new AD biomarker, reflecting dysfunctional activation of neuronal glutamatergic N-methyl-d-aspartate receptor (NMDAR). In this study, we measured blood serum and CSF concentration of two NMDAR modulators, such as d-serine and d-aspartate, in a cohort of drug-free subjects encompassing the whole AD clinical spectrum. In addition, we also analyzed d-serine levels in a cohort of post-mortem AD and control cortex samples. We reported unaltered serum and CSF concentrations of d-serine and d-aspartate in AD patients both during the AD progression and compared to non-demented controls. Accordingly, no correlation was detected between serum or CSF d-serine content and mini-mental state examination or Clinical Dementia Rating. Similarly, cortical d-serine levels were also unaltered in post-mortem samples of AD patients. Overall, our results failed to confirm previous findings indicating the CSF d-serine as a novel biomarker for AD.
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Affiliation(s)
- Tommaso Nuzzo
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy; CEINGE Biotecnologie Avanzate, Naples, Italy
| | - Mattia Miroballo
- IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | | | - Andrea Mancini
- Section of Neurology, Department of Medicine, University of Perugia, Italy
| | - Lorenzo Gaetani
- Section of Neurology, Department of Medicine, University of Perugia, Italy
| | - Robert Nisticò
- School of Pharmacy, University of Rome Tor Vergata, Rome, Italy; Pharmacology of synaptic Plasticity Lab, European Brain Research Institute, Rome, Italy
| | - Paolo Eusebi
- Section of Neurology, Department of Medicine, University of Perugia, Italy
| | - Masumi Katane
- Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Hiroshi Homma
- Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Paolo Calabresi
- Neurologia, Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy; Dipartimento di Neuroscienze, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Francesco Errico
- Department of Agricultural Sciences, University of Naples "Federico II", Portici, Italy
| | - Lucilla Parnetti
- Section of Neurology, Department of Medicine, University of Perugia, Italy.
| | - Alessandro Usiello
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy; CEINGE Biotecnologie Avanzate, Naples, Italy.
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Dysfunctional d-aspartate metabolism in BTBR mouse model of idiopathic autism. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140531. [PMID: 32853769 DOI: 10.1016/j.bbapap.2020.140531] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 07/22/2020] [Accepted: 07/31/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND Autism spectrum disorders (ASD) comprise a heterogeneous group of neurodevelopmental conditions characterized by impairment in social interaction, deviance in communication, and repetitive behaviors. Dysfunctional ionotropic NMDA and AMPA receptors, and metabotropic glutamate receptor 5 activity at excitatory synapses has been recently linked to multiple forms of ASD. Despite emerging evidence showing that d-aspartate and d-serine are important neuromodulators of glutamatergic transmission, no systematic investigation on the occurrence of these D-amino acids in preclinical ASD models has been carried out. METHODS Through HPLC and qPCR analyses we investigated d-aspartate and d-serine metabolism in the brain and serum of four ASD mouse models. These include BTBR mice, an idiopathic model of ASD, and Cntnap2-/-, Shank3-/-, and 16p11.2+/- mice, three established genetic mouse lines recapitulating high confidence ASD-associated mutations. RESULTS Biochemical and gene expression mapping in Cntnap2-/-, Shank3-/-, and 16p11.2+/- failed to find gross cerebral and serum alterations in d-aspartate and d-serine metabolism. Conversely, we found a striking and stereoselective increased d-aspartate content in the prefrontal cortex, hippocampus and serum of inbred BTBR mice. Consistent with biochemical assessments, in the same brain areas we also found a robust reduction in mRNA levels of d-aspartate oxidase, encoding the enzyme responsible for d-aspartate catabolism. CONCLUSIONS Our results demonstrated the presence of disrupted d-aspartate metabolism in a widely used animal model of idiopathic ASD. GENERAL SIGNIFICANCE Overall, this work calls for a deeper investigation of D-amino acids in the etiopathology of ASD and related developmental disorders.
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Biochemical characterization of d-aspartate oxidase from Caenorhabditis elegans: its potential use in the determination of free d-glutamate in biological samples. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140442. [PMID: 32376478 DOI: 10.1016/j.bbapap.2020.140442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/26/2020] [Accepted: 04/29/2020] [Indexed: 12/16/2022]
Abstract
d-Aspartate oxidase (DDO) is a flavin adenine dinucleotide (FAD)-containing flavoprotein that stereospecifically acts on acidic d-amino acids (i.e., free d-aspartate and d-glutamate). Mammalian DDO, which exhibits higher activity toward d-aspartate than d-glutamate, is presumed to regulate levels of d-aspartate in the body and is not thought to degrade d-glutamate in vivo. By contrast, three DDO isoforms are present in the nematode Caenorhabditis elegans, DDO-1, DDO-2, and DDO-3, all of which exhibit substantial activity toward d-glutamate as well as d-aspartate. In this study, we optimized the Escherichia coli culture conditions for production of recombinant C. elegans DDO-1, purified the protein, and showed that it is a flavoprotein with a noncovalently but tightly attached FAD. Furthermore, C. elegans DDO-1, but not mammalian (rat) DDO, efficiently and selectively degraded d-glutamate in addition to d-aspartate, even in the presence of various other amino acids. Thus, C. elegans DDO-1 might be a useful tool for determining these acidic d-amino acids in biological samples.
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Prenatal expression of d-aspartate oxidase causes early cerebral d-aspartate depletion and influences brain morphology and cognitive functions at adulthood. Amino Acids 2020; 52:597-617. [DOI: 10.1007/s00726-020-02839-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/06/2020] [Indexed: 12/25/2022]
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d-Aspartate oxidase: distribution, functions, properties, and biotechnological applications. Appl Microbiol Biotechnol 2020; 104:2883-2895. [DOI: 10.1007/s00253-020-10439-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 01/28/2020] [Accepted: 02/05/2020] [Indexed: 12/16/2022]
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Molla G, Chaves‐Sanjuan A, Savinelli A, Nardini M, Pollegioni L. Structure and kinetic properties of humand‐aspartate oxidase, the enzyme‐controllingd‐aspartate levels in brain. FASEB J 2019; 34:1182-1197. [DOI: 10.1096/fj.201901703r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 11/05/2019] [Accepted: 11/10/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Gianluca Molla
- Dipartimento di Biotecnologie e Scienze della Vita Università degli studi dell’Insubria Varese Italy
| | | | - Antonio Savinelli
- Dipartimento di Biotecnologie e Scienze della Vita Università degli studi dell’Insubria Varese Italy
| | - Marco Nardini
- Dipartimento di Bioscienze Università degli studi di Milano Milano Italy
| | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita Università degli studi dell’Insubria Varese Italy
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Katane M, Kuwabara H, Nakayama K, Saitoh Y, Miyamoto T, Sekine M, Homma H. Rat d-aspartate oxidase is more similar to the human enzyme than the mouse enzyme. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1866:806-812. [PMID: 29292239 DOI: 10.1016/j.bbapap.2017.12.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 11/29/2022]
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, as well as chronic pain. Thus, appropriate regulation of d-aspartate is believed to be important for maintaining proper neural activity in the nervous system. Accordingly, much attention has been paid to the role(s) of DDO in the metabolism of d-aspartate in vivo, and the physiological functions of DDO have been actively investigated using experimental rats and mice. However, detailed characterisation of rat DDO has not yet been performed, and little is known about species-specific differences in the properties of mammalian DDOs. In this study, the structural and enzymatic properties of purified recombinant rat, mouse and human DDOs were examined and compared. The results showed that rat DDO is more similar to human DDO than to mouse DDO. This work provides useful insight into the use of rats as an experimental model for investigating the biological significance of human DDO and/or d-aspartate. This article is part of a Special Issue entitled: d-Amino acids: biology in the mirror, edited by Dr. Loredano Pollegioni, Dr. Jean-Pierre Mothet and Dr. Molla Gianluca.
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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
| | - Hisashi Kuwabara
- 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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