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Li M, Qiu J, Yan G, Zheng X, Li A. How does the neurotoxin β-N-methylamino-L-alanine exist in biological matrices and cause toxicity? THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 922:171255. [PMID: 38417517 DOI: 10.1016/j.scitotenv.2024.171255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/01/2024]
Abstract
The neurotoxin β-N-methylamino-L-alanine (BMAA) has been deemed as a risk factor for some neurodegenerative diseases such as amyotrophic lateral sclerosis/parkinsonism dementia complex (ALS/PDC). This possible link has been proved in some primate models and cell cultures with the appearance that BMAA exposure can cause excitotoxicity, formation of protein aggregates, and/or oxidative stress. The neurotoxin BMAA extensively exists in the environment and can be transferred through the food web to human beings. In this review, the occurrence, toxicological mechanisms, and characteristics of BMAA were comprehensively summarized, and proteins and peptides were speculated as its possible binding substances in biological matrices. It is difficult to compare the published data from previous studies due to the inconsistent analytical methods and components of BMAA. The binding characteristics of BMAA should be focused on to improve our understanding of its health risk to human health in the future.
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Affiliation(s)
- Min Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Jiangbing Qiu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Guowang Yan
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Xianyao Zheng
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Aifeng Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China.
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2
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van Onselen R, Kennedy C, Downing TG. Protection against β-N-methylamino-l-alanineꟷinduced vesicular monoamine transporter 2 inhibition by hydroxyl-containing proteinogenic amino acids. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2024; 107:104399. [PMID: 38403141 DOI: 10.1016/j.etap.2024.104399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 02/02/2024] [Accepted: 02/21/2024] [Indexed: 02/27/2024]
Abstract
β-N-methylamino-l-alanine (BMAA) has been shown to inhibit vesicular monoamine transporter 2 (VMAT2), thereby preventing the uptake of monoaminergic neurotransmitters into platelet dense granules and synaptic vesicles. The inhibition is hypothesized to be through direct association of BMAA with hydroxyl groupꟷcontaining amino acid residues in VMAT2. This study evaluated whether BMAA-induced inhibition of VMAT2 could be prevented directly by co-incubation of BMAA with amino acids, and if this protection was specific for BMAA inhibition of VMAT2. l-tyrosine, and to a lesser extent l-serine, was able to prevent BMAA-induced VMAT2 inhibition in a concentration-dependent manner, whereas neither l-threonine nor amino acids without side chain hydroxyl groups could reduce this inhibition. Reserpine-induced VMAT2 inhibition was unaffected by any of the amino acids. These data support the hypothesized interaction between BMAA and hydroxyl groupꟷcontaining amino acids and suggests that this interaction might be leveraged to protect against the toxicity of BMAA.
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Affiliation(s)
- Rianita van Onselen
- Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa; Department of Biochemistry and Microbiology, Nelson Mandela University, Gqeberha, South Africa.
| | - Chanté Kennedy
- Department of Biochemistry and Microbiology, Nelson Mandela University, Gqeberha, South Africa.
| | - Tim G Downing
- Department of Biochemistry and Microbiology, Nelson Mandela University, Gqeberha, South Africa.
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3
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van Onselen R, Downing TG. Uptake of β-N-methylamino-L-alanine (BMAA) into glutamate-specific synaptic vesicles: Exploring the validity of the excitotoxicity mechanism of BMAA. Neurosci Lett 2024; 821:137593. [PMID: 38103629 DOI: 10.1016/j.neulet.2023.137593] [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: 09/28/2023] [Revised: 12/01/2023] [Accepted: 12/07/2023] [Indexed: 12/19/2023]
Abstract
The first mechanism of toxicity proposed for the cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) was excitotoxicity, and this was supported by numerous in vitro studies in which overactivation of both ionotropic and metabotropic glutamate receptors was reported. However, the excitotoxicity of BMAA is weak in comparison with other known excitotoxins and on par with that of glutamate, implying that to achieve sufficient synaptic concentrations of BMAA to cause classical in vivo excitotoxicity, BMAA must either accumulate in synapses to allow persistent glutamate receptor activation or it must be released in sufficiently high concentrations into synapses to cause the overexcitation. Since it has been shown that BMAA can be readily removed from synapses, release of high concentrations of BMAA into synapses must be shown to confirm its role as an excitotoxin in in vivo systems. This study therefore sought to evaluate the uptake of BMAA into synaptic vesicles and to determine if BMAA affects the uptake of glutamate into synaptic vesicles. There was no evidence to support uptake of BMAA into glutamate-specific synaptic vesicles but there was some indication that BMAA may affect the uptake of glutamate into synaptic vesicles. The uptake of BMAA into synaptic vesicles isolated from areas other than the cerebral cortex should be investigated before definite conclusions can be drawn about the role of BMAA as an excitotoxin.
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Affiliation(s)
- Rianita van Onselen
- Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa; Department of Biochemistry and Microbiology, Nelson Mandela University, Gqeberha, South Africa
| | - Tim G Downing
- Department of Biochemistry and Microbiology, Nelson Mandela University, Gqeberha, South Africa.
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4
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Violi JP, Pu L, Pravadali-Cekic S, Bishop DP, Phillips CR, Rodgers KJ. Effects of the Toxic Non-Protein Amino Acid β-Methylamino-L-Alanine (BMAA) on Intracellular Amino Acid Levels in Neuroblastoma Cells. Toxins (Basel) 2023; 15:647. [PMID: 37999510 PMCID: PMC10674354 DOI: 10.3390/toxins15110647] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/08/2023] [Accepted: 11/08/2023] [Indexed: 11/25/2023] Open
Abstract
The cyanobacterial non-protein amino acid (AA) β-Methylamino-L-alanine (BMAA) is considered to be a neurotoxin. BMAA caused histopathological changes in brains and spinal cords of primates consistent with some of those seen in early motor neuron disease; however, supplementation with L-serine protected against some of those changes. We examined the impact of BMAA on AA concentrations in human neuroblastoma cells in vitro. Cells were treated with 1000 µM BMAA and intracellular free AA concentrations in treated and control cells were compared at six time-points over a 48 h culture period. BMAA had a profound effect on intracellular AA levels at specific time points but in most cases, AA homeostasis was re-established in the cell. The most heavily impacted amino acid was serine which was depleted in BMAA-treated cells from 9 h onwards. Correction of serine depletion could be a factor in the observation that supplementation with L-serine protects against BMAA toxicity in vitro and in vivo. AAs that could potentially be involved in protection against BMAA-induced oxidation such as histidine, tyrosine, and phenylalanine were depleted in cells at later time points.
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Affiliation(s)
- Jake P. Violi
- School of Life Sciences, Faculty of Science, The University of Technology Sydney, Ultimo, NSW 2007, Australia; (J.P.V.); (L.P.); (C.R.P.)
| | - Lisa Pu
- School of Life Sciences, Faculty of Science, The University of Technology Sydney, Ultimo, NSW 2007, Australia; (J.P.V.); (L.P.); (C.R.P.)
| | - Sercan Pravadali-Cekic
- School of Mathematical and Physical Sciences, Faculty of Science, The University of Technology Sydney, Ultimo, NSW 2007, Australia (D.P.B.)
| | - David P. Bishop
- School of Mathematical and Physical Sciences, Faculty of Science, The University of Technology Sydney, Ultimo, NSW 2007, Australia (D.P.B.)
| | - Connor R. Phillips
- School of Life Sciences, Faculty of Science, The University of Technology Sydney, Ultimo, NSW 2007, Australia; (J.P.V.); (L.P.); (C.R.P.)
| | - Kenneth J. Rodgers
- School of Life Sciences, Faculty of Science, The University of Technology Sydney, Ultimo, NSW 2007, Australia; (J.P.V.); (L.P.); (C.R.P.)
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5
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Weeks RD, Banack SA, Howell S, Thunga P, Metcalf JS, Green AJ, Cox PA, Planchart A. The Effects of Long-term, Low-dose β-N-methylamino-L-alanine (BMAA) Exposures in Adult SOD G93R Transgenic Zebrafish. Neurotox Res 2023; 41:481-495. [PMID: 37552461 PMCID: PMC11216512 DOI: 10.1007/s12640-023-00658-z] [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: 09/22/2022] [Revised: 06/07/2023] [Accepted: 07/01/2023] [Indexed: 08/09/2023]
Abstract
β-N-Methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid produced by cyanobacteria, which has been implicated in several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). It is postulated that chronic exposure to BMAA can lead to formation of protein aggregates, oxidative stress, and/or excitotoxicity, which are mechanisms involved in the etiology of ALS. While specific genetic mutations are identified in some instances of ALS, it is likely that a combination of genetic and environmental factors, such as exposure to the neurotoxin BMAA, contributes to disease. We used a transgenic zebrafish with an ALS-associated mutation, compared with wild-type fish to explore the potential neurotoxic effects of BMAA through chronic long-term exposures. While our results revealed low concentrations of BMAA in the brains of exposed fish, we found no evidence of decreased swim performance or behavioral differences that might be reflective of neurodegenerative disease. Further research is needed to determine if chronic BMAA exposure in adult zebrafish is a suitable model to study neurodegenerative disease initiation and/or progression.
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Affiliation(s)
- Ryan D. Weeks
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
- Program in Toxicology, North Carolina State University, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
| | - Sandra A. Banack
- Brain Chemistry Labs, Institute for Ethnomedicine, Box 3464, Jackson, WY 83001, USA
| | - Shaunacee Howell
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Preethi Thunga
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - James S. Metcalf
- Brain Chemistry Labs, Institute for Ethnomedicine, Box 3464, Jackson, WY 83001, USA
| | - Adrian J. Green
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
- Program in Toxicology, North Carolina State University, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
| | - Paul A. Cox
- Brain Chemistry Labs, Institute for Ethnomedicine, Box 3464, Jackson, WY 83001, USA
| | - Antonio Planchart
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
- Program in Toxicology, North Carolina State University, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
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6
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Li A, Liu J, Qiu J, Wang G, Zheng X, Ji Y, Yan G, Zhao P, Wu X, Yan W, Zhang L, Li M, Fu Y. Cell cycle of microalga Isochrysis galbana arrested by neurotoxin β-N-methylamino-l-alanine and corresponding molecular mechanisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 874:162445. [PMID: 36848993 DOI: 10.1016/j.scitotenv.2023.162445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 02/20/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
The phycotoxin β-N-methylamino-l-alanine (BMAA) has attracted attention due to its risks to marine organisms and human health. In this study, approximately 85 % of synchronized cells of the marine microalga Isochrysis galbana were arrested at the cell cycle G1 phase by BMAA at 6.5 μM for a 24-h exposure. The concentration of chlorophyll a (Chl a) gradually decreased, while the maximum quantum yield of PSII (Fv/Fm), the maximum relative electron transport rate (rETRmax), light utilization efficiency (α) and half-saturated light irradiance (Ik) reduced early and recovered gradually in I. galbana exposed to BMAA in 96-h batch cultures. Transcriptional expression of I. galbana analyzed at 10, 12, and 16 h disclosed multiple mechanisms of BMAA to suppress the microalgal growth. Production of ammonia and glutamate was limited by the down-regulation of nitrate transporters, glutamate synthase, glutamine synthetase, cyanate hydrolase, and formamidase. Diverse extrinsic proteins related to PSII, PSI, cytochrome b6f complex, and ATPase were influenced by BMAA at transcriptional level. Suppression of the DNA replication and mismatch repair pathways increased the accumulation of misfolded proteins, which was reflected by the up-regulated expression of proteasome to accelerate proteolysis. This study improves our understanding of the chemical ecology impacts of BMAA in marine ecosystems.
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Affiliation(s)
- Aifeng Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China.
| | - Jianwei Liu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Jiangbing Qiu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Guixiang Wang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Xianyao Zheng
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Ying Ji
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Guowang Yan
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Peng Zhao
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Xizhen Wu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Wenhui Yan
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Lei Zhang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Min Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Yilei Fu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
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7
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β-N-Methylamino-L-Alanine (BMAA) Modulates the Sympathetic Regulation and Homeostasis of Polyamines. Toxins (Basel) 2023; 15:toxins15020141. [PMID: 36828455 PMCID: PMC9960692 DOI: 10.3390/toxins15020141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/02/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023] Open
Abstract
The neurotoxin β-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid produced by cyanobacteria. Non-neuronal toxicity of BMAA is poorly studied with a reported increase in reactive oxygen species and a decrease in the antioxidant capacity of liver, kidney, and colorectal adenocarcinoma cells. The aim of this research is to study the toxicity of BMAA (0.1-1 mM) on mitochondria and submitochondrial particles with ATPase activity, on the semicarbazide-sensitive amino oxidases (SSAOs) activity of rat liver, and on an in vitro model containing functionally active excitable tissues-regularly contracting heart muscle preparation with a preserved autonomic innervation. For the first time the BMAA-dependent inhibition of SSAO activity, the elimination of the positive inotropic effect of adrenergic innervation, and the direct and reversible inhibition of adrenaline signaling in ventricular myocytes with 1 mM BMAA were observed. Additionally, it is confirmed that 1 mM BMAA can activate mitochondrial ATPase indirectly. It is concluded that a higher dose of BMAA may influence multiple physiological and pathological processes as it slows down the degradation of biogenic amines, downregulates the sympathetic neuromediation, and embarrasses the cell signaling of adrenergic receptors.
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8
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Lopicic S, Svirčev Z, Palanački Malešević T, Kopitović A, Ivanovska A, Meriluoto J. Environmental Neurotoxin β- N-Methylamino-L-alanine (BMAA) as a Widely Occurring Putative Pathogenic Factor in Neurodegenerative Diseases. Microorganisms 2022; 10:2418. [PMID: 36557671 PMCID: PMC9781992 DOI: 10.3390/microorganisms10122418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/28/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
In the present review we have discussed the occurrence of β-N-methylamino-L-alanine (BMAA) and its natural isomers, and the organisms and sample types in which the toxin(s) have been detected. Further, the review discusses general pathogenic mechanisms of neurodegenerative diseases, and how modes of action of BMAA fit in those mechanisms. The biogeography of BMAA occurrence presented here contributes to the planning of epidemiological research based on the geographical distribution of BMAA and human exposure. Analysis of BMAA mechanisms in relation to pathogenic processes of neurodegeneration is used to critically assess the potential significance of the amino acid as well as to identify gaps in our understanding. Taken together, these two approaches provide the basis for the discussion on the potential role of BMAA as a secondary factor in neurodegenerative diseases, the rationale for further research and possible directions the research can take, which are outlined in the conclusions.
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Affiliation(s)
- Srdjan Lopicic
- Faculty of Medicine, University of Belgrade, Dr Subotića Starijeg 8, 11000 Belgrade, Serbia
| | - Zorica Svirčev
- Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 2, 21000 Novi Sad, Serbia
- Faculty of Science and Engineering, Biochemistry, Åbo Akademi University, Tykistökatu 6A, 20520 Turku, Finland
| | - Tamara Palanački Malešević
- Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 2, 21000 Novi Sad, Serbia
| | - Aleksandar Kopitović
- Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 3, 21000 Novi Sad, Serbia
| | - Aleksandra Ivanovska
- Innovation Center of the Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia
| | - Jussi Meriluoto
- Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 2, 21000 Novi Sad, Serbia
- Faculty of Science and Engineering, Biochemistry, Åbo Akademi University, Tykistökatu 6A, 20520 Turku, Finland
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9
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Koksharova OA, Safronova NA. Non-Proteinogenic Amino Acid β-N-Methylamino-L-Alanine (BMAA): Bioactivity and Ecological Significance. Toxins (Basel) 2022; 14:539. [PMID: 36006201 PMCID: PMC9414260 DOI: 10.3390/toxins14080539] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 07/28/2022] [Accepted: 08/04/2022] [Indexed: 11/21/2022] Open
Abstract
Research interest in a non-protein amino acid β-N-methylamino-L-alanine (BMAA) arose due to the discovery of a connection between exposure to BMAA and the occurrence of neurodegenerative diseases. Previous reviews on this topic either considered BMAA as a risk factor for neurodegenerative diseases or focused on the problems of detecting BMAA in various environmental samples. Our review is devoted to a wide range of fundamental biological problems related to BMAA, including the molecular mechanisms of biological activity of BMAA and the complex relationships between producers of BMAA and the environment in various natural ecosystems. At the beginning, we briefly recall the most important facts about the producers of BMAA (cyanobacteria, microalgae, and bacteria), the pathways of BMAA biosynthesis, and reliable methods of identification of BMAA. The main distinctive feature of our review is a detailed examination of the molecular mechanisms underlying the toxicity of BMAA to living cells. A brand new aspect, not previously discussed in any reviews, is the effect of BMAA on cyanobacterial cells. These recent studies, conducted using transcriptomics and proteomics, revealed potent regulatory effects of BMAA on the basic metabolism and cell development of these ancient photoautotrophic prokaryotes. Exogenous BMAA strongly influences cell differentiation and primary metabolic processes in cyanobacteria, such as nitrogen fixation, photosynthesis, carbon fixation, and various biosynthetic processes involving 2-oxoglutarate and glutamate. Cyanobacteria were found to be more sensitive to exogenous BMAA under nitrogen-limited growth conditions. We suggest a hypothesis that this toxic diaminoacid can be used by phytoplankton organisms as a possible allelopathic tool for controlling the population of cyanobacterial cells during a period of intense competition for nitrogen and other resources in various ecosystems.
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Affiliation(s)
- Olga A. Koksharova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
- Institute of Molecular Genetics of National Research Center “Kurchatov Institute”, Kurchatov Square, 2, 123182 Moscow, Russia
| | - Nina A. Safronova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
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10
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Kim SY, Hedberg P, Winder M, Rydberg S. Evidence of 2,4-diaminobutyric acid (DAB) production as a defense mechanism in diatom Thalassiosira pseudonana. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 249:106210. [PMID: 35665646 DOI: 10.1016/j.aquatox.2022.106210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 05/23/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
The neurotoxic secondary metabolite β-N-methylamino-L-alanine (BMAA) and its structural isomer 2,4-diaminobutyric acid (DAB) are known to be produced by various phytoplankton groups. Despite the worldwide spread of these toxin producers, no obvious role and function of BMAA and DAB in diatoms have been identified. Here, we investigated the effects of biotic factors, i.e., predators and competitors, as possible causes of BMAA and/or DAB regulation in the two diatom species Phaeodactylum tricornutum and Thalassiosira pseudonana. DAB was specifically regulated in T. pseudonana by the presence of predators and competitors. The effects of DAB on both diatoms as competitors and on the copepod Tigriopus sp. as predator at individual and at population levels were examined. The toxic effects of DAB on the growth of T. pseudonana and the population of Tigriopus sp. were significant. The effect of DAB as a defensive secondary metabolite is assumed to be environmentally relevant depending on the number of the copepods. The results show a potential function of DAB that can play an important role in defense mechanisms of T. pseudonana.
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Affiliation(s)
- Sea-Yong Kim
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE 10691 Stockholm, Sweden
| | - Per Hedberg
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE 10691 Stockholm, Sweden
| | - Monika Winder
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE 10691 Stockholm, Sweden
| | - Sara Rydberg
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE 10691 Stockholm, Sweden.
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11
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Courtier A, Potheret D, Giannoni P. Environmental bacteria as triggers to brain disease: Possible mechanisms of toxicity and associated human risk. Life Sci 2022; 304:120689. [DOI: 10.1016/j.lfs.2022.120689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/11/2022] [Accepted: 06/01/2022] [Indexed: 11/24/2022]
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12
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Review of Cyanotoxicity Studies Based on Cell Cultures. J Toxicol 2022; 2022:5647178. [PMID: 35509523 PMCID: PMC9061046 DOI: 10.1155/2022/5647178] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 02/28/2022] [Accepted: 03/25/2022] [Indexed: 12/23/2022] Open
Abstract
Cyanotoxins (CTs) are a large and diverse group of toxins produced by the peculiar photosynthetic prokaryotes of the domain Cyanoprokaryota. Toxin-producing aquatic cyanoprokaryotes can develop in mass, causing “water blooms” or “cyanoblooms,” which may lead to environmental disaster—water poisoning, extinction of aquatic life, and even to human death. CT studies on single cells and cells in culture are an important stage of toxicological studies with increasing impact for their further use for scientific and clinical purposes, and for policies of environmental protection. The higher cost of animal use and continuous resistance to the use of animals for scientific and toxicological studies lead to a progressive increase of cell lines use. This review aims to present (1) the important results of the effects of CT on human and animal cell lines, (2) the methods and concentrations used to obtain these results, (3) the studied cell lines and their tissues of origin, and (4) the intracellular targets of CT. CTs reviewed are presented in alphabetical order as follows: aeruginosins, anatoxins, BMAA (β-N-methylamino-L-alanine), cylindrospermopsins, depsipeptides, lipopolysaccharides, lyngbyatoxins, microcystins, nodularins, cyanobacterial retinoids, and saxitoxins. The presence of all these data in a review allows in one look to advance the research on CT using cell cultures by facilitating the selection of the most appropriate methods, conditions, and cell lines for future toxicological, pharmacological, and physiological studies.
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13
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Ra D, Sa B, Sl B, Js M, Sj M, DA D, Ew S, O K, Eb B, Ad C, Vx T, Gg G, Pa C, Dc M, Wg B. Is Exposure to BMAA a Risk Factor for Neurodegenerative Diseases? A Response to a Critical Review of the BMAA Hypothesis. Neurotox Res 2021; 39:81-106. [PMID: 33547590 PMCID: PMC7904546 DOI: 10.1007/s12640-020-00302-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 12/15/2022]
Abstract
In a literature survey, Chernoff et al. (2017) dismissed the hypothesis that chronic exposure to β-N-methylamino-L-alanine (BMAA) may be a risk factor for progressive neurodegenerative disease. They question the growing scientific literature that suggests the following: (1) BMAA exposure causes ALS/PDC among the indigenous Chamorro people of Guam; (2) Guamanian ALS/PDC shares clinical and neuropathological features with Alzheimer's disease, Parkinson's disease, and ALS; (3) one possible mechanism for protein misfolds is misincorporation of BMAA into proteins as a substitute for L-serine; and (4) chronic exposure to BMAA through diet or environmental exposures to cyanobacterial blooms can cause neurodegenerative disease. We here identify multiple errors in their critique including the following: (1) their review selectively cites the published literature; (2) the authors reported favorably on HILIC methods of BMAA detection while the literature shows significant matrix effects and peak coelution in HILIC that may prevent detection and quantification of BMAA in cyanobacteria; (3) the authors build alternative arguments to the BMAA hypothesis, rather than explain the published literature which, to date, has been unable to refute the BMAA hypothesis; and (4) the authors erroneously attribute methods to incorrect studies, indicative of a failure to carefully consider all relevant publications. The lack of attention to BMAA research begins with the review's title which incorrectly refers to BMAA as a "non-essential" amino acid. Research regarding chronic exposure to BMAA as a cause of human neurodegenerative diseases is emerging and requires additional resources, validation, and research. Here, we propose strategies for improvement in the execution and reporting of analytical methods and the need for additional and well-executed inter-lab comparisons for BMAA quantitation. We emphasize the need for optimization and validation of analytical methods to ensure that they are fit-for-purpose. Although there remain gaps in the literature, an increasingly large body of data from multiple independent labs using orthogonal methods provides increasing evidence that chronic exposure to BMAA may be a risk factor for neurological illness.
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Affiliation(s)
- Dunlop Ra
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY, USA.
| | - Banack Sa
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY, USA
| | - Bishop Sl
- Lewis Research Group, Faculty of Science, University of Calgary, Alberta, Canada
| | - Metcalf Js
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY, USA
| | - Murch Sj
- Department of Chemistry, University of British Columbia, Kelowna, BC, Canada
| | - Davis DA
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Stommel Ew
- Department of Neurology, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - Karlsson O
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Brittebo Eb
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | | | - Tan Vx
- Department of Biological Sciences, Macquarie University Centre for Motor Neuron Disease Research, Macquarie University, Ryde, Australia
| | - Guillemin Gg
- Department of Biological Sciences, Macquarie University Centre for Motor Neuron Disease Research, Macquarie University, Ryde, Australia
| | - Cox Pa
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY, USA
| | - Mash Dc
- Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Bradley Wg
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL, USA
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14
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Abstract
Among the 20 cytoplasmic aminoacyl-tRNA synthetases (aaRSs), alanyl-tRNA synthetase (AlaRS) has unique features. AlaRS is the only aaRS that exclusively recognizes a single G3:U70 wobble base pair in the acceptor stem of tRNA, which serves as the identity element for both the synthetic and the proofreading activities of the synthetase. The recognition is relaxed during evolution and eukaryotic AlaRS can mis-aminoacylate noncognate tRNAs with a G4:U69 base pair seemingly as a deliberate gain of function for unknown reasons. Unlike other class II aaRSs, dimerization of AlaRS is not necessarily required for aminoacylation possibly due to functional compensations from the C-terminal domain (C-Ala). In contrast to other 19 cytoplasmic aaRSs that append additional domains or motifs to acquire new functions during evolution, the functional expansion of AlaRS is likely achieved through transformations of the existing C-Ala. Given both essential canonical and diverse non-canonical roles of AlaRS, dysfunction of AlaRS leads to neurodegenerative disorders in human and various pathological phenotypes in mouse models. In this review, the uniqueness of AlaRS in both physiological and pathological events is systematically discussed, with a particular focus on its novel functions gained in evolution.
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Affiliation(s)
- Han Zhang
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, Yunnan, China
| | - Xiang-Lei Yang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA
| | - Litao Sun
- School of Public Health (Shenzhen), Sun Yat-sen University, Guangdong, China
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15
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Western Pacific ALS-PDC: Evidence implicating cycad genotoxins. J Neurol Sci 2020; 419:117185. [PMID: 33190068 DOI: 10.1016/j.jns.2020.117185] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 09/20/2020] [Accepted: 09/29/2020] [Indexed: 12/12/2022]
Abstract
Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS-PDC) is a disappearing neurodegenerative disorder of apparent environmental origin formerly hyperendemic among Chamorros of Guam-USA, Japanese residents of the Kii Peninsula, Honshu Island, Japan and Auyu-Jakai linguistic groups of Papua-Indonesia on the island of New Guinea. The most plausible etiology is exposure to genotoxins in seed of neurotoxic cycad plants formerly used for food and/or medicine. Primary suspicion falls on methylazoxymethanol (MAM), the aglycone of cycasin and on the non-protein amino acid β-N-methylamino-L-alanine, both of which are metabolized to formaldehyde. Human and animal studies suggest: (a) exposures occurred early in life and sometimes during late fetal brain development, (b) clinical expression of neurodegenerative disease appeared years or decades later, and (c) pathological changes in various tissues indicate the disease was not confined to the CNS. Experimental evidence points to toxic molecular mechanisms involving DNA damage, epigenetic changes, transcriptional mutagenesis, neuronal cell-cycle reactivation and perturbation of the ubiquitin-proteasome system that led to polyproteinopathy and culminated in neuronal degeneration. Lessons learned from research on ALS-PDC include: (a) familial disease may reflect common toxic exposures across generations, (b) primary disease prevention follows cessation of exposure to culpable environmental triggers; and (c) disease latency provides a prolonged period during which to intervene therapeutically. Exposure to genotoxic chemicals ("slow toxins") in the early stages of life should be considered in the search for the etiology of ALS-PDC-related neurodegenerative disorders, including sporadic forms of ALS, progressive supranuclear palsy and Alzheimer's disease.
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16
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β-Ν-Methylamino-L-alanine interferes with nitrogen assimilation in the cyanobacterium, non-BMAA producer, Synechococcus sp. TAU-MAC 0499. Toxicon 2020; 185:147-155. [PMID: 32687889 DOI: 10.1016/j.toxicon.2020.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/18/2020] [Accepted: 07/13/2020] [Indexed: 02/08/2023]
Abstract
The production of β-Ν-methylamino-L-alanine (BMAA) in cyanobacteria is triggered by nitrogen-starvation conditions and its biological role, albeit unknown, is associated with nitrogen assimilation. In the present study, the effect of BMAA (773 μg L-1) on nitrogen metabolism and physiology of the non-diazotrophic cyanobacterium and non-BMAA producer, Synechococcus sp. TAU-MAC 0499, was investigated. In order to study the combined effect of nitrogen availability and BMAA, nitrogen-starvation conditions were induced by transferring cells in nitrogen-free medium and subsequently exposing the cultures to BMAA. After short-term treatment (180 min) and in the presence of nitrogen, BMAA inhibited glutamine synthetase, which resulted in low concentration of glutamine. In the absence of nitrogen, although there was no effect on glutamine synthetase, a possible perturbation in nitrogen assimilation is reflected on the significant decrease in glutamate levels. During the long-term exposure (24-96 h), growth, photosynthetic pigments and total protein were not affected by BMAA exposure, except for an increase in protein and phycocyanin levels at 48 h in nitrogen replete conditions. Results suggest that BMAA interferes with nitrogen assimilation, in a different way, depending on the presence or absence of combined nitrogen, providing novel data on the potential biological role of BMAA.
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17
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van Onselen R, Scott LL, Downing TG. Evaluating amino acids as protectants against β-N-methylamino-l-alanine-induced developmental neurotoxicity in a rat model. Toxicol Appl Pharmacol 2020; 403:115140. [PMID: 32682829 DOI: 10.1016/j.taap.2020.115140] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 06/15/2020] [Accepted: 07/13/2020] [Indexed: 12/28/2022]
Abstract
With accumulating evidence that supports the role of β-N-methylamino-l-alanine (BMAA) in neurodegeneration, it is necessary to elucidate the mechanisms and modes of BMAA toxicity so as to facilitate the search for potential preventative/therapeutic strategies. Daily supplementation with l-serine was suggested as a possible therapy to treat BMAA-induced neurotoxicity, based on the hypothesized mechanism of BMAA misincorporation into proteins for l-serine. As an alternative to misincorporation, it was hypothesized that BMAA toxicity may, in part, be due to its high affinity for associating with hydroxyl group-containing amino acids, and that a dietary excess of the hydroxyl-containing l-serine might offer protection by binding to BMAA and reducing its toxicity. Additionally, l-serine can also reduce the uptake of BMAA into human cells by competitive uptake at ASCT2, and l-phenylalanine, by competitive uptake at LAT1, and l-alanine, by competitive uptake at SNAT2, can also reduce BMAA uptake into human cells. The aim of this study was therefore to determine the protective value of l-serine, l-phenylalanine and l-alanine in reducing the effects of neonatal exposure to BMAA in a Sprague Dawley rat model. Pre-treatment with l-phenylalanine reduced the observed behavioral abnormalities and neuropathologies by 60-70% in most cases. l-serine was also effective in reducing some of the behavioral abnormalities and neuropathologies, most markedly spinal cord neuronal loss. However, the protective effect of l-serine was obfuscated by neuropathies that were observed in l-serine-treated control male rats. l-alanine had no effect in protecting against BMAA-induced neurotoxicity, suggesting that competitive amino acid uptake plays a minor role in protecting against BMAA-induced neurotoxicity.
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Affiliation(s)
- Rianita van Onselen
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77000, Port Elizabeth, 6031, South Africa
| | - Laura Louise Scott
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77000, Port Elizabeth, 6031, South Africa
| | - Tim G Downing
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77000, Port Elizabeth, 6031, South Africa..
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18
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Nunes-Costa D, Magalhães JD, G-Fernandes M, Cardoso SM, Empadinhas N. Microbial BMAA and the Pathway for Parkinson's Disease Neurodegeneration. Front Aging Neurosci 2020; 12:26. [PMID: 32317956 PMCID: PMC7019015 DOI: 10.3389/fnagi.2020.00026] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/23/2020] [Indexed: 12/12/2022] Open
Abstract
The neurotoxin β-N-methylamino-L-alanine (BMAA) is a natural non-proteinogenic diamino acid produced by several species of both prokaryotic (cyanobacteria) and eukaryotic (diatoms and dinoflagellates) microorganisms. BMAA has been shown to biomagnify through the food chain in some ecosystems, accumulating for example in seafood such as shellfish and fish, common dietary sources of BMAA whose ingestion may have possible neuronal consequences. In addition to its excitotoxic potential, BMAA has been implicated in protein misfolding and aggregation, inhibition of specific enzymes and neuroinflammation, all hallmark features of neurodegenerative diseases. However, the exact molecular mechanisms of neurotoxicity remain to be elucidated in detail. Although BMAA is commonly detected in its free form, complex BMAA-containing molecules have also been identified such as the paenilamicins, produced by an insect gut bacterial pathogen. On the other hand, production of BMAA or BMAA-containing molecules by members of the human gut microbiota, for example by non-photosynthetic cyanobacteria, the Melainabacteria, remains only hypothetical. In any case, should BMAA reach the gut it may interact with cells of the mucosal immune system and neurons of the enteric nervous system (ENS) and possibly target the mitochondria. Here, we review the available evidence and hint on possible mechanisms by which chronic exposure to dietary sources of this microbial neurotoxin may drive protein misfolding and mitochondrial dysfunction with concomitant activation of innate immune responses, chronic low-grade gut inflammation, and ultimately the neurodegenerative features observed across the gut-brain axis in Parkinson's disease (PD).
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Affiliation(s)
- Daniela Nunes-Costa
- CNC–Center for Neuroscience and Cell
Biology, University of Coimbra, Coimbra,
Portugal
- Ph.D. Programme in Biomedicine and Experimental
Biology (PDBEB), Institute for Interdisciplinary Research, University of
Coimbra, Coimbra,
Portugal
| | - João Duarte Magalhães
- CNC–Center for Neuroscience and Cell
Biology, University of Coimbra, Coimbra,
Portugal
- Ph.D. Programme in Biomedicine and Experimental
Biology (PDBEB), Institute for Interdisciplinary Research, University of
Coimbra, Coimbra,
Portugal
| | - Maria G-Fernandes
- CNC–Center for Neuroscience and Cell
Biology, University of Coimbra, Coimbra,
Portugal
| | - Sandra Morais Cardoso
- CNC–Center for Neuroscience and Cell
Biology, University of Coimbra, Coimbra,
Portugal
- Institute of Cellular and Molecular Biology,
Faculty of Medicine, University of Coimbra,
Coimbra, Portugal
| | - Nuno Empadinhas
- CNC–Center for Neuroscience and Cell
Biology, University of Coimbra, Coimbra,
Portugal
- Institute for Interdisciplinary Research
(IIIUC), University of Coimbra, Coimbra,
Portugal
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19
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Han NC, Bullwinkle TJ, Loeb KF, Faull KF, Mohler K, Rinehart J, Ibba M. The mechanism of β-N-methylamino-l-alanine inhibition of tRNA aminoacylation and its impact on misincorporation. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49898-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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20
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Han NC, Bullwinkle TJ, Loeb KF, Faull KF, Mohler K, Rinehart J, Ibba M. The mechanism of β- N-methylamino-l-alanine inhibition of tRNA aminoacylation and its impact on misincorporation. J Biol Chem 2019; 295:1402-1410. [PMID: 31862734 DOI: 10.1074/jbc.ra119.011714] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/10/2019] [Indexed: 11/06/2022] Open
Abstract
β-N-methylamino-l-alanine (BMAA) is a nonproteinogenic amino acid that has been associated with neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD). BMAA has been found in human protein extracts; however, the mechanism by which it enters the proteome is still unclear. It has been suggested that BMAA is misincorporated at serine codons during protein synthesis, but direct evidence of its cotranslational incorporation is currently lacking. Here, using LC-MS-purified BMAA and several biochemical assays, we sought to determine whether any aminoacyl-tRNA synthetase (aaRS) utilizes BMAA as a substrate for aminoacylation. Despite BMAA's previously predicted misincorporation at serine codons, following a screen for amino acid activation in ATP/PPi exchange assays, we observed that BMAA is not a substrate for human seryl-tRNA synthetase (SerRS). Instead, we observed that BMAA is a substrate for human alanyl-tRNA synthetase (AlaRS) and can form BMAA-tRNAAla by escaping from the intrinsic AlaRS proofreading activity. Furthermore, we found that BMAA inhibits both the cognate amino acid activation and the editing functions of AlaRS. Our results reveal that, in addition to being misincorporated during translation, BMAA may be able to disrupt the integrity of protein synthesis through multiple different mechanisms.
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Affiliation(s)
- Nien-Ching Han
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43220
| | - Tammy J Bullwinkle
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43220
| | - Kaeli F Loeb
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43220
| | - Kym F Faull
- Pasarow Mass Spectrometry Laboratory, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California 90024-1759
| | - Kyle Mohler
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut 06520.,Systems Biology Institute, Yale University, New Haven, Connecticut 06520
| | - Jesse Rinehart
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut 06520.,Systems Biology Institute, Yale University, New Haven, Connecticut 06520
| | - Michael Ibba
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43220
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21
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Production of β-methylamino-L-alanine (BMAA) and Its Isomers by Freshwater Diatoms. Toxins (Basel) 2019; 11:toxins11090512. [PMID: 31480725 PMCID: PMC6784237 DOI: 10.3390/toxins11090512] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 08/23/2019] [Accepted: 08/29/2019] [Indexed: 12/14/2022] Open
Abstract
β-methylamino-L-alanine (BMAA) is a non-protein amino acid that has been implicated as a risk factor for motor neurone disease (MND). BMAA is produced by a wide range of cyanobacteria globally and by a small number of marine diatoms. BMAA is commonly found with two of its constitutional isomers: 2,4-diaminobutyric acid (2,4-DAB), and N-(2-aminoethyl)glycine (AEG). The isomer 2,4-DAB, like BMAA, has neurotoxic properties. While many studies have shown BMAA production by cyanobacteria, few studies have looked at other algal groups. Several studies have shown BMAA production by marine diatoms; however, there are no studies examining freshwater diatoms. This study aimed to determine if some freshwater diatoms produced BMAA, and which diatom taxa are capable of BMAA, 2,4-DAB and AEG production. Five axenic diatom cultures were established from river and lake sites across eastern Australia. Cultures were harvested during the stationary growth phase and intracellular amino acids were extracted. Using liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS), diatom extracts were analysed for the presence of both free and protein-associated BMAA, 2,4-DAB and AEG. Of the five diatom cultures analysed, four were found to have detectable BMAA and AEG, while 2,4-DAB was found in all cultures. These results show that BMAA production by diatoms is not confined to marine genera and that the prevalence of these non-protein amino acids in Australian freshwater environments cannot be solely attributed to cyanobacteria.
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22
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Kim KY, Hwang SK, Park SY, Kim MJ, Jun DY, Kim YH. l-Serine protects mouse hippocampal neuronal HT22 cells against oxidative stress-mediated mitochondrial damage and apoptotic cell death. Free Radic Biol Med 2019; 141:447-460. [PMID: 31326607 DOI: 10.1016/j.freeradbiomed.2019.07.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 07/15/2019] [Accepted: 07/17/2019] [Indexed: 12/20/2022]
Abstract
The cytoprotective mechanism of l-serine against oxidative stress-mediated neuronal apoptosis was investigated in mouse hippocampal neuronal HT22 cells. Treatment with the reactive oxygen species (ROS) inducer 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) increased cytosolic and mitochondrial ROS and apoptosis, without necrosis, in HT22 cells. ROS-mediated apoptosis was accompanied by the induction of the endoplasmic reticulum (ER) stress-mediated apoptotic pathway, involving CHOP/GADD153 upregulation, JNK and p38 MAPK activation, and caspase-12 and caspase-8 activation, and subsequent induction of the mitochondrial apoptotic pathway through BAK and BAX activation, mitochondrial membrane potential (Δψm) loss, caspase-9 and caspase-3 activation, PARP cleavage, and nucleosomal DNA fragmentation. However, the DMNQ-caused ROS elevation and ER stress- and mitochondrial damage-induced apoptotic events were dose-dependently suppressed by co-treatment with l-serine (7.5-20 mM). Although DMNQ reduced both the intracellular glutathione (GSH) level and the ratios of reduced GSH to oxidized GSH (GSSG), the reduction was restored by co-treatment with l-serine. Co-treatment with GSH or N-acetylcysteine also blocked DMNQ-caused ROS elevation and apoptosis; however, co-treatment with the GSH synthesis inhibitor buthionine sulfoximine significantly promoted ROS-mediated apoptosis and counteracted the protection by l-serine. In HT22 cells, DMNQ treatment appeared to tilt the mitochondrial fusion-fission balance toward fission by down-regulating the levels of profusion proteins (MFN1/2 and OPA1) and inhibitory phosphorylation of profission protein DRP1 at Ser-637, resulting in mitochondrial fragmentation. These DMNQ-caused alterations were prevented by l-serine. A comparison of mitochondrial energetic function between DMNQ- and DMNQ/l-serine-treated HT22 cells showed that the DMNQ-caused impairment of the mitochondrial energy generation capacity was restored by l-serine. These results demonstrate that l-serine can protect neuronal cells against oxidative stress-mediated apoptotic cell death by contributing to intracellular antioxidant GSH synthesis and maintaining the mitochondrial fusion-fission balance.
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Affiliation(s)
- Ki Yun Kim
- Laboratory of Immunobiology, School of Life Science and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea
| | - Su-Kyeong Hwang
- Department of Pediatrics, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Shin Young Park
- Laboratory of Immunobiology, School of Life Science and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea
| | - Min Ju Kim
- Astrogen Inc., Techno-Building 313, Kyungpook National University, Daegu, 41566, South Korea
| | - Do Youn Jun
- Astrogen Inc., Techno-Building 313, Kyungpook National University, Daegu, 41566, South Korea
| | - Young Ho Kim
- Laboratory of Immunobiology, School of Life Science and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea.
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23
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Metabolism of the neurotoxic amino acid β-N-methylamino-L-alanine in human cell culture models. Toxicon 2019; 168:131-139. [PMID: 31330193 DOI: 10.1016/j.toxicon.2019.07.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/12/2019] [Accepted: 07/16/2019] [Indexed: 12/12/2022]
Abstract
Human dietary exposure to the environmental neurotoxin β-N-methylamino-L-alanine (BMAA) has been implicated in an increased risk of developing sporadic neurodegenerative diseases like Alzheimer's and amyotrophic lateral sclerosis. Evidence suggests that humans are exposed to BMAA globally, but very little is known about BMAA metabolism in mammalian systems, let alone in humans. The most plausible, evidence-based mechanisms of BMAA toxicity rely on the metabolic stability of the amino acid and that, following ingestion, it enters the circulatory system unmodified. BMAA crosses from the intestinal lumen into the circulatory system, and the small intestine and liver are the first sites for dietary amino acid metabolism. Both tissues have substantial amino acid metabolic needs, which are largely fulfilled by dietary amino acids. Metabolism of BMAA in these tissues has been largely overlooked, yet is important in gauging the true human exposure risk. Here we investigate the potential for BMAA metabolism by the human liver and small intestine, using in vitro cell systems. Data show that BMAA metabolism via common proteinogenic amino acid metabolic pathways is negligible, and that in the presence of other amino acids cellular uptake of BMAA is substantially reduced. These data suggest that the majority of ingested BMAA remains unmodified following passage through the small intestine and liver. This not only supports oral BMAA exposure as a plausible exposure route to toxic doses of BMAA, but also supports previous notions that protein deficient diets or malnutrition may increase an individual's susceptibility to BMAA absorption and subsequent toxicity.
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24
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Sieroslawska A, Rymuszka A. Assessment of the cytotoxic impact of cyanotoxin beta-N-methylamino-L-alanine on a fish immune cell line. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 212:214-221. [PMID: 31132739 DOI: 10.1016/j.aquatox.2019.05.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/16/2019] [Accepted: 05/16/2019] [Indexed: 06/09/2023]
Abstract
Beta-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid produced by several cyanobacteria species. It is considered to be a potent neurotoxin. Although its neurotoxic effects are well studied, other negative effects of BMAA have not yet been completely elucidated. In the present study, we studied the cytotoxic effects of a wide range of concentrations of BMAA (0.25-2.0 mM) on a stable fish immune cell line (CLC) obtained from carp monocytes. The cells exposed to higher concentrations of BMAA exhibited an altered morphology, changed ATP levels, and reduced proliferation. On the basis of toxic effects of BMAA on lysosomes, mitochondrial dehydrogenases activity, and cell membrane integrity, we determined its cytotoxic concentrations. We also investigated effects of the toxin at non-cytotoxic concentrations on the basic functions of CLC cells. BMAA did not affect the production and release of IL-1β or phagocytic activity of the cells. However, higher non-toxic BMAA concentrations altered the levels of extracellular and intracellular total proteins compared to those in control cells.
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Affiliation(s)
- Anna Sieroslawska
- Department of Animal Physiology and Toxicology, Institute of Biotechnology, The John Paul II Catholic University of Lublin, Poland.
| | - Anna Rymuszka
- Department of Animal Physiology and Toxicology, Institute of Biotechnology, The John Paul II Catholic University of Lublin, Poland
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25
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Manolidi K, Triantis TM, Kaloudis T, Hiskia A. Neurotoxin BMAA and its isomeric amino acids in cyanobacteria and cyanobacteria-based food supplements. JOURNAL OF HAZARDOUS MATERIALS 2019; 365:346-365. [PMID: 30448548 DOI: 10.1016/j.jhazmat.2018.10.084] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 06/09/2023]
Abstract
Cyanobacteria are photosynthetic microorganisms distributed globally in aquatic and terrestrial environments. They are also industrially cultivated to be used as dietary supplements, as they have a high nutritional value; however, they are also known to produce a wide range of toxic secondary metabolites, called cyanotoxins. BMAA (β-methylamino-l-alanine) and its most common structural isomers, DAB (2,4-diaminobutyric acid) and AEG (N-2-aminoethylglycine) produced by cyanobacteria, are non-proteinogenic amino acids that have been associated with neurodegenerative diseases. A possible route of exposure to those amino acids is through consumption of food supplements based on cyanobacteria. The review critically discusses existing reports regarding the occurrence of BMAA, DAB and AEG in cyanobacteria and cyanobacteria-based food supplements. It is shown that inconsistencies in reported results could be attributed to performance of different methods of extraction and analysis applied and in ambiguities regarding determination of soluble and bound fractions of the compounds. The critical aspect of this review aims to grow awareness of human intake of neurotoxic amino acids, while results presented in literature concerning dietary supplements aim to promote further research, quality control as well as development of guidelines for cyanotoxins in food products.
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Affiliation(s)
- Korina Manolidi
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece; National and Kapodistrian University of Athens, Faculty of Chemistry, 15784, Panepistimiopolis, Athens, Greece.
| | - Theodoros M Triantis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece.
| | - Triantafyllos Kaloudis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece; Water Quality Control Department, Athens Water Supply and Sewerage Company - EYDAP SA, Athens, Greece.
| | - Anastasia Hiskia
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece.
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van Onselen R, Downing TG. β- N-methylamino-L-alanine Inhibits Human Catalase Activity: Possible Implications for Neurodegenerative Disease Development. Int J Toxicol 2019; 38:129-134. [PMID: 30663459 DOI: 10.1177/1091581818821921] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The naturally produced, nonprotein amino acid β- N-methylamino-l-alanine (BMAA) has been proposed as a significant contributor to sporadic neurodegenerative disease development worldwide. However, the existing hypothesized mechanisms of toxicity do not adequately explain the role of BMAA in neurodegenerative disease development. There is evidence for BMAA-induced enzyme inhibition, but the effect of BMAA on human stress response enzymes has received little attention, despite the well-described role of oxidative stress in neurodegenerative disease development. The aim of this study was therefore to investigate the effect of BMAA on human catalase activity and compare it to the known inhibitor 3-amino-1,2,4-triazole. BMAA inhibited human erythrocyte catalase in a cell-free exposure to the same extent as the known inhibitor. Based on enzyme kinetics, the inhibition appears to be noncompetitive, possibly as a result of BMAA binding in the nicotinamide adenine dinucleotide phosphate (NADPH) binding site. BMAA-induced catalase inhibition was also observed in a human cell line culture. We therefore propose that BMAA-induced enzyme inhibition, specifically catalase inhibition, is a mechanism of toxicity that may contribute to the neurotoxicity of BMAA, further supporting the role of BMAA in neurodegenerative disease development.
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Affiliation(s)
- Rianita van Onselen
- 1 Department of Biochemistry and Microbiology, Nelson Mandela University, Port Elizabeth, South Africa
| | - Tim G Downing
- 1 Department of Biochemistry and Microbiology, Nelson Mandela University, Port Elizabeth, South Africa
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