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Fujino Y, Ueyama M, Ishiguro T, Ozawa D, Ito H, Sugiki T, Murata A, Ishiguro A, Gendron T, Mori K, Tokuda E, Taminato T, Konno T, Koyama A, Kawabe Y, Takeuchi T, Furukawa Y, Fujiwara T, Ikeda M, Mizuno T, Mochizuki H, Mizusawa H, Wada K, Ishikawa K, Onodera O, Nakatani K, Petrucelli L, Taguchi H, Nagai Y. FUS regulates RAN translation through modulating the G-quadruplex structure of GGGGCC repeat RNA in C9orf72-linked ALS/FTD. eLife 2023; 12:RP84338. [PMID: 37461319 PMCID: PMC10393046 DOI: 10.7554/elife.84338] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023] Open
Abstract
Abnormal expansions of GGGGCC repeat sequence in the noncoding region of the C9orf72 gene is the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). The expanded repeat sequence is translated into dipeptide repeat proteins (DPRs) by noncanonical repeat-associated non-AUG (RAN) translation. Since DPRs play central roles in the pathogenesis of C9-ALS/FTD, we here investigate the regulatory mechanisms of RAN translation, focusing on the effects of RNA-binding proteins (RBPs) targeting GGGGCC repeat RNAs. Using C9-ALS/FTD model flies, we demonstrated that the ALS/FTD-linked RBP FUS suppresses RAN translation and neurodegeneration in an RNA-binding activity-dependent manner. Moreover, we found that FUS directly binds to and modulates the G-quadruplex structure of GGGGCC repeat RNA as an RNA chaperone, resulting in the suppression of RAN translation in vitro. These results reveal a previously unrecognized regulatory mechanism of RAN translation by G-quadruplex-targeting RBPs, providing therapeutic insights for C9-ALS/FTD and other repeat expansion diseases.
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Grants
- Scientific Research on Innovative Areas (Brain Protein Aging and Dementia Control) 17H05699 Ministry of Education, Culture, Sports, Science and Technology
- Scientific Research on Innovative Areas (Brain Protein Aging and Dementia Control) 17H05705 Ministry of Education, Culture, Sports, Science and Technology
- Transformative Research Areas (A) (Multifaceted Proteins) 20H05927 Ministry of Education, Culture, Sports, Science and Technology
- Strategic Research Program for Brain Sciences 11013026 Ministry of Education, Culture, Sports, Science and Technology
- Scientific Research (B) 21H02840 Japan Society for the Promotion of Science
- Scientific Research (B) 20H03602 Japan Society for the Promotion of Science
- Scientific Research (C) 15K09331 Japan Society for the Promotion of Science
- Scientific Research (C) 19K07823 Japan Society for the Promotion of Science
- Scientific Research (C) 17K07291 Japan Society for the Promotion of Science
- Young Scientists (A) 17H05091 Japan Society for the Promotion of Science
- Young Scientists (B) 25860733 Japan Society for the Promotion of Science
- Challenging Exploratory Research 24659438 Japan Society for the Promotion of Science
- Challenging Exploratory Research 18K19515 Japan Society for the Promotion of Science
- Health Labor Sciences Research Grant for Research on Development of New Drugs H24-Soyaku-Sogo-002 Ministry of Health, Labor and Welfare, Japan
- Strategic Research Program for Brain Sciences JP15dm0107026 Japan Agency for Medical Research and Development
- Strategic Research Program for Brain Sciences JP20dm0107061 Japan Agency for Medical Research and Development
- Practical Research Projects for Rare/Intractable Diseases JP16ek0109018 Japan Agency for Medical Research and Development
- Practical Research Projects for Rare/Intractable Diseases JP19ek0109222 Japan Agency for Medical Research and Development
- Practical Research Projects for Rare/Intractable Diseases JP20ek0109316 Japan Agency for Medical Research and Development
- Platform Project for Supporting Drug Discovery and Life Science Research JP19am0101072 Japan Agency for Medical Research and Development
- Intramural Research Grants for Neurological and Psychiatric Disorders 27-7 National Center of Neurology and Psychiatry
- Intramural Research Grants for Neurological and Psychiatric Disorders 27-9 National Center of Neurology and Psychiatry
- Intramural Research Grants for Neurological and Psychiatric Disorders 30-3 National Center of Neurology and Psychiatry
- Intramural Research Grants for Neurological and Psychiatric Disorders 30-9 National Center of Neurology and Psychiatry
- Intramural Research Grants for Neurological and Psychiatric Disorders 3-9 National Center of Neurology and Psychiatry
- IBC Grant H28 Japan Amyotrophic Lateral Sclerosis Association
- 2017 Takeda Science Foundation
- 2016 Takeda Science Foundation
- 2018 SENSHIN Medical Research Foundation
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Affiliation(s)
- Yuzo Fujino
- Department of Neurology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
- Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Morio Ueyama
- Department of Neurology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Suita, Japan
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Taro Ishiguro
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Tokyo, Japan
| | - Daisaku Ozawa
- Department of Neurology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Hayato Ito
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Toshihiko Sugiki
- Laboratory of Molecular Biophysics, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Asako Murata
- Department of Regulatory Bioorganic Chemistry, The Institute of Scientific and28 Industrial Research, Osaka University, Osaka, Japan
| | - Akira Ishiguro
- Research Center for Micro-nano Technology, Hosei University, Tokyo, Japan
| | - Tania Gendron
- Department of Neuroscience, Mayo Clinic, Jacksonville, United States
| | - Kohji Mori
- Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Eiichi Tokuda
- Department of Chemistry, Keio University, Kanagawa, Japan
| | - Tomoya Taminato
- Department of Neurology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Takuya Konno
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata, Japan
| | - Akihide Koyama
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata, Japan
| | - Yuya Kawabe
- Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Toshihide Takeuchi
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Suita, Japan
- Life Science Research Institute, Kindai University, Osaka, Japan
| | | | - Toshimichi Fujiwara
- Laboratory of Molecular Biophysics, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Manabu Ikeda
- Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Toshiki Mizuno
- Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hidehiro Mizusawa
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Tokyo, Japan
| | - Keiji Wada
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Kinya Ishikawa
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Tokyo, Japan
| | - Osamu Onodera
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata, Japan
| | - Kazuhiko Nakatani
- Department of Regulatory Bioorganic Chemistry, The Institute of Scientific and28 Industrial Research, Osaka University, Osaka, Japan
| | | | - Hideki Taguchi
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan
| | - Yoshitaka Nagai
- Department of Neurology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Suita, Japan
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
- Department of Neurology, Osaka University Graduate School of Medicine, Osaka, Japan
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2
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Asami S, Suzuki M, Nakayama T, Shimoda Y, Miura M, Kato K, Tokuda E, Ono S, Kawakubo T, Nishizawa K, Yamanaka K, Suzuki T. Apoptotic Effects of a Thioether Analog of Vitamin K 3 in a Human Leukemia Cell Line. Int J Toxicol 2021; 40:517-529. [PMID: 34610772 DOI: 10.1177/10915818211047992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Research suggests that thioether analogs of vitamin K3 (VK3) can act to preserve the phosphorylation of epidermal growth factor receptors by blocking enzymes (phosphatases) responsible for their dephosphorylation. Additionally, these derivatives can induce apoptosis via mitogen-activated protein kinase and caspase-3 activation, inducing reactive oxygen species (ROS) production, and apoptosis. However, vitamin K1 exhibits only weak inhibition of phosphatase activity, while the ability of VK3 to cause oxidative DNA damage has raised concerns about carcinogenicity. Hence, in the current study, we designed, synthesized, and screened a number of VK3 analogs for their ability to enhance phosphorylation activity, without inducing off-target effects, such as DNA damage. 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay revealed that each analog produced a different level of cytotoxicity in the Jurkat human leukemia cell line; however, none elicited a cytotoxic effect that differed significantly from that of the control. Of the VK3 analogs, CPD5 exhibited the lowest EC50, and flow cytometry results showed that apoptosis was induced at final concentrations of ≥10 μM; hence, only 0.1, 1, and 10 μM were evaluated in subsequent assays. Furthermore, CPD5 did not cause vitamin K-attributed ROS generation and was found to be associated with a significant increase in caspase 3 expression, indicating that, of the synthesized thioether VK3 analogs, CPD5 was a more potent inducer of apoptosis than VK3. Hence, further elucidation of the apoptosis-inducing effect of CPD5 may reveal its efficacy in other neoplastic cells and its potential as a medication.
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Affiliation(s)
- Satoru Asami
- Laboratory of Clinical Medicine, 12976Nihon University School of Pharmacy, Chiba, Japan
| | - Mikana Suzuki
- Laboratory of Clinical Medicine, 12976Nihon University School of Pharmacy, Chiba, Japan.,Department of Pharmacy, Toho University Medical Center Omori Hospital, Tokyo, Japan
| | - Toshimitsu Nakayama
- Department of Hospital Pharmacy, 38113Nihon University School of Medicine, Tokyo, Japan
| | - Yasuyo Shimoda
- Laboratory of Environmental Toxicology and Carcinogenesis, 539261Nihon University School of Pharmacy, Chiba, Japan
| | - Motofumi Miura
- Department of Molecular Chemistry, Nihon University School of Pharmacy, Chiba, Japan
| | - Koichi Kato
- Laboratory of Environmental Toxicology and Carcinogenesis, 539261Nihon University School of Pharmacy, Chiba, Japan
| | - Eiichi Tokuda
- Laboratory of Clinical Medicine, 12976Nihon University School of Pharmacy, Chiba, Japan
| | - Shinichi Ono
- Laboratory of Clinical Medicine, 12976Nihon University School of Pharmacy, Chiba, Japan
| | - Takashi Kawakubo
- Department of Pharmacy, 157437Jikei University School of Medicine, Tokyo, Japan
| | - Kenji Nishizawa
- Department of Pharmacy, Toho University Medical Center Omori Hospital, Tokyo, Japan
| | - Kenzo Yamanaka
- Laboratory of Environmental Toxicology and Carcinogenesis, 539261Nihon University School of Pharmacy, Chiba, Japan
| | - Takashi Suzuki
- Laboratory of Clinical Medicine, 12976Nihon University School of Pharmacy, Chiba, Japan
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3
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Hirose M, Asano M, Watanabe-Matsumoto S, Yamanaka K, Abe Y, Yasui M, Tokuda E, Furukawa Y, Misawa H. Stagnation of glymphatic interstitial fluid flow and delay in waste clearance in the SOD1-G93A mouse model of ALS. Neurosci Res 2020; 171:74-82. [PMID: 33316302 DOI: 10.1016/j.neures.2020.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/18/2020] [Accepted: 10/28/2020] [Indexed: 01/23/2023]
Abstract
Overexpression and mislocalization of aquaporin-4 (AQP4) in the SOD1G93A mouse model of amyotrophic lateral sclerosis (ALS) have previously been reported. However, how alterations of AQP4 affect interstitial bulk flow in the brain and spinal cord, the so-called glymphatic system, is unclear. Here, we report an enhanced accumulation of disease-associated SOD1 species including SOD1 oligomers in SOD1G93A;AQP4-/- mice compared with SOD1G93A mice during ALS disease progression, as analyzed by sandwich ELISA. By directly injecting SOD1 oligomers into the spinal cord parenchyma, we observed a significantly larger delay in clearance of biotinylated or fluorescent-labeled SOD1 oligomers in AQP4-/- mice than in wild-type mice. Furthermore, when we injected the fluorescent-labeled tracer protein ovalbumin into the cisterna magna and analyzed the tracer distribution in the cervical spinal cord, approximately 35 % processing ability was found to be reduced in SOD1G93A mice compared to wild-type mice. These results suggest that the glymphatic system is abnormal and that waste clearance is delayed in SOD1G93A mice.
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Affiliation(s)
- Mikako Hirose
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, 105-8512, Japan
| | - Mito Asano
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, 105-8512, Japan
| | | | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan
| | - Yoichiro Abe
- Department of Pharmacology, School of Medicine, Keio University, Tokyo, 160-8582, Japan
| | - Masato Yasui
- Department of Pharmacology, School of Medicine, Keio University, Tokyo, 160-8582, Japan
| | - Eiichi Tokuda
- Department of Chemistry, Keio University, Yokohama, 223-8522, Japan
| | | | - Hidemi Misawa
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, 105-8512, Japan.
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4
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Anzai I, Tokuda E, Handa S, Misawa H, Akiyama S, Furukawa Y. Oxidative misfolding of Cu/Zn-superoxide dismutase triggered by non-canonical intramolecular disulfide formation. Free Radic Biol Med 2020; 147:187-199. [PMID: 31863908 DOI: 10.1016/j.freeradbiomed.2019.12.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/05/2019] [Accepted: 12/17/2019] [Indexed: 12/14/2022]
Abstract
Misfolded Cu/Zn-superoxide dismutase (SOD1) is a pathological species in a subset of amyotrophic lateral sclerosis (ALS). Oxidative stress is known to increase in affected spinal cords of ALS and is thus considered to cause damages on SOD1 leading to the misfolding and aggregation. Despite this, it still remains elusive what triggers misfolding of SOD1 under oxidizing environment. Here, we show that a thiol group of Cys111 in SOD1 is oxidized to a sulfenic acid with hydrogen peroxide and reveal that further dissociation of the bound metal ions from the oxidized SOD1 allows another free Cys residue (Cys6) to nucleophilically attack the sulfenylated Cys111. As a result, an intra-molecular disulfide bond forms between Cys6 and Cys111. Such an abnormal SOD1 with the non-canonical disulfide bond was conformationally extended with significant cytotoxicity as well as high propensity to aggregate. Taken together, we propose a new model of SOD1 misfolding under oxidizing environment, in which formation of the non-canonical intramolecular disulfide bond plays a pivotal role.
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Affiliation(s)
- Itsuki Anzai
- Department of Chemistry, Keio University, Yokohama, 223-8522, Japan
| | - Eiichi Tokuda
- Department of Chemistry, Keio University, Yokohama, 223-8522, Japan
| | - Sumika Handa
- Department of Chemistry, Keio University, Yokohama, 223-8522, Japan
| | - Hidemi Misawa
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, 105-8512, Japan
| | - Shuji Akiyama
- Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, 444-8585, Japan; Department of Functional Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8585, Japan
| | - Yoshiaki Furukawa
- Department of Chemistry, Keio University, Yokohama, 223-8522, Japan.
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5
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Tokuda E, Takei YI, Ohara S, Fujiwara N, Hozumi I, Furukawa Y. Wild-type Cu/Zn-superoxide dismutase is misfolded in cerebrospinal fluid of sporadic amyotrophic lateral sclerosis. Mol Neurodegener 2019; 14:42. [PMID: 31744522 PMCID: PMC6862823 DOI: 10.1186/s13024-019-0341-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 10/31/2019] [Indexed: 02/06/2023] Open
Abstract
Background A subset of familial forms of amyotrophic lateral sclerosis (ALS) are caused by mutations in the gene coding Cu/Zn-superoxide dismutase (SOD1). Mutant SOD1 proteins are susceptible to misfolding and abnormally accumulated in spinal cord, which is most severely affected in ALS. It, however, remains quite controversial whether misfolding of wild-type SOD1 is involved in more prevalent sporadic ALS (sALS) cases without SOD1 mutations. Methods Cerebrospinal fluid (CSF) from patients including sALS as well as several other neurodegenerative diseases and non-neurodegenerative diseases was examined with an immunoprecipitation assay and a sandwich ELISA using antibodies specifically recognizing misfolded SOD1. Results We found that wild-type SOD1 was misfolded in CSF from all sALS cases examined in this study. The misfolded SOD1 was also detected in CSF from a subset of Parkinson’s disease and progressive supranuclear palsy, albeit with smaller amounts than those in sALS. Furthermore, the CSF samples containing the misfolded SOD1 exhibited significant toxicity toward motor neuron-like NSC-34 cells, which was ameliorated by removal of the misfolded wild-type SOD1 with immunoprecipitation. Conclusions Taken together, we propose that misfolding of wild-type SOD1 in CSF is a common pathological process of ALS cases regardless of SOD1 mutations.
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Affiliation(s)
- Eiichi Tokuda
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, Yokohama, 223-8522, Japan
| | - Yo-Ichi Takei
- Department of Neurology, Matsumoto Medical Center, Matsumoto, 399-0021, Japan
| | - Shinji Ohara
- Department of Neurology, Matsumoto Medical Center, Matsumoto, 399-0021, Japan.,Department of Neurology, Iida Hospital, Iida, 395-8505, Japan
| | - Noriko Fujiwara
- Department of Biochemistry, Hyogo College of Medicine, Nishinomiya, 663-8501, Japan
| | - Isao Hozumi
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University, Gifu, 501-1196, Japan.,Department of Neurology and Geriatrics, Gifu University Graduate School of Medicine, Gifu, 501-1194, Japan
| | - Yoshiaki Furukawa
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, Yokohama, 223-8522, Japan.
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6
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Tokuda E, Marklund SL, Furukawa Y. [Prion-like Properties of Misfolded Cu/Zn-superoxide Dismutase in Amyotrophic Lateral Sclerosis: Update and Perspectives]. YAKUGAKU ZASSHI 2019; 139:1015-1019. [PMID: 31257248 DOI: 10.1248/yakushi.18-00165-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disease that is characterized by the loss of motor neurons, which results in progressive muscle atrophy. The pathology spreads from the initial site of onset to contiguous anatomic regions. Mutations in the gene encoding Cu/Zn-superoxide dismutase (SOD1) have been identified in a dominantly inherited form of ALS (ALS-SOD1). A major hallmark of ALS-SOD1 is the abnormal accumulation of conformationally aberrant SOD1 protein (i.e., misfolded SOD1) within motor neurons. Emerging experimental evidence has suggested that misfolded proteins associated with neurodegenerative diseases exhibit prion-like properties, i.e., misfolded proteins act as conformational templates that convert normal proteins into a pathogenic form. Possibly as a result of this prion-like self-propagation property, misfolded forms of pathological proteins are considered to accumulate in the central nervous system and cause neurodegeneration. In this article, we review recent evidence for the role of prion-like mechanisms in ALS-SOD1. In particular, we discuss the propensity of misfolded SOD1 to act as a pathological seed, spread between cells, and propagate neuroanatomically.
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Iida M, Nakamura M, Tokuda E, Niwa T, Ishida T, Hayashi SI. P21 has the potential to become the monitoring marker for the CDK4/6 inhibitors resistance in breast cancer. Ann Oncol 2018. [DOI: 10.1093/annonc/mdy268.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Tokuda E, Nomura T, Ohara S, Watanabe S, Yamanaka K, Morisaki Y, Misawa H, Furukawa Y. A copper-deficient form of mutant Cu/Zn-superoxide dismutase as an early pathological species in amyotrophic lateral sclerosis. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2119-2130. [PMID: 29551730 DOI: 10.1016/j.bbadis.2018.03.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 02/27/2018] [Accepted: 03/14/2018] [Indexed: 12/13/2022]
Abstract
Dominant mutations in the gene encoding copper and zinc-binding superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS). Abnormal accumulation of misfolded SOD1 proteins in spinal motoneurons is a major pathological hallmark in SOD1-related ALS. Dissociation of copper and/or zinc ions from SOD1 has been shown to trigger the protein aggregation/oligomerization in vitro, but the pathological contribution of such metal dissociation to the SOD1 misfolding still remains obscure. Here, we tested the relevance of the metal-deficient SOD1 in the misfolding in vivo by developing a novel antibody (anti-apoSOD), which exclusively recognized mutant SOD1 deficient in metal ions at its copper-binding site. Notably, anti-apoSOD-reactive species were detected specifically in the spinal cords of the ALS model mice only at their early pre-symptomatic stages but not at the end stage of the disease. The cerebrospinal fluid as well as the spinal cord homogenate of one SOD1-ALS patient also contained the anti-apoSOD-reactive species. Our results thus suggest that metal-deficiency in mutant SOD1 at its copper-binding site is one of the earliest pathological features in SOD1-ALS.
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Affiliation(s)
- Eiichi Tokuda
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, Yokohama 223-8522, Japan
| | - Takao Nomura
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, Yokohama 223-8522, Japan.
| | - Shinji Ohara
- Department of Neurology, Matsumoto Medical Center, Matsumoto 399-0021, Japan.
| | - Seiji Watanabe
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan.
| | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan.
| | - Yuta Morisaki
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo 105-8512, Japan
| | - Hidemi Misawa
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo 105-8512, Japan.
| | - Yoshiaki Furukawa
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, Yokohama 223-8522, Japan.
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Tokuda E, Komatsu T, Sasaki S, Tsuboi K, Nakamura M, Iida M, Niwa T, Saito M, Hayashi SI. Abstract P4-03-12: Effects of PI3K inhibitors on endocrine-resistant cell lines and differences in the characteristics of ER positive breast cancer cells after acquired resistance to the inhibitors. Cancer Res 2018. [DOI: 10.1158/1538-7445.sabcs17-p4-03-12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background
Mutations in phosphatidylinositol 3-kinase (PI3K), which encodes the catalytic subunit of PI3Kα, is one of the most frequent genomic alterations and is found in about 40% of estrogen receptor (ER)-positive, HER2 negative breast cancers. PIK3CA mutations promote the growth and proliferation of cancers via activation of the PI3K/mammalian target of rapamycin pathway and can mediate resistance to endocrine therapies in breast cancer. Although several clinical trials for PI3K inhibitors (PI3Kis) in ER-positive metastatic breast cancers are ongoing, the effects of PI3Kis on endocrine-resistant breast cancers with various characteristics and definitive biomarkers of PI3Kis are unclear. Using endocrine-resistant cells established in our laboratory, we evaluated the efficacy of PI3Ki in these cell lines and identified the characteristics associated with acquired resistance to PI3Kis in endocrine-resistant cells.
Results
Long-term estrogen deprivation-resistant (EDR) cell lines and fulvestrant-resistant cell lines (MFR and TFR) were established from MCF-7 and T-47D cells in our previous studies. These cell lines showed different ER expression levels, including high expression (EDR-1), low expression (EDR-2, -3), or no expression (MFR, TFR); all of these cell lines had the same PIK3CA mutations as the parental cell lines. The pan-class1 PI3Ki buparlisib (BKM120) and α-specific PI3K inhibitor alpelisib (BYL719) inhibited the proliferation of endocrine-resistant cell lines when compared with their parental cells. Among endocrine-resistant cells, MFR cells were dramatically inhibited by PI3Kis. Colony formation assays indicated that MFR cells were more sensitive to PI3Kis than other cells lines. Next, we established PI3Ki- and everolimus-resistant cell lines from EDR-1, EDR-2, and MFR cells using BKM120, BYL719, and everolimus. Analysis of the time required to generate resistant cells showed that MFR cells required twice as long to acquire resistance compared with EDR cells. Furthermore, the time required to acquire resistance to BYL719 was shorter than that for BKM120. BYL719-resistant (BYL-R) cells were effectively inhibited by BKM120 to a degree similar to that of parental cells; however, BYL-R cells lost sensitivity to BYL719 and everolimus. Evelolimus-resistant (EVE-R) cells were also the same. In contrast, BKM120-resistant (BKM-R) cells showed less sensitivity to BKM120, BYL719, and everolimus. In other words, the pan-PI3Ki BKM120 was able to inhibit the growth of BYL-R and EVE-R cells, whereas BYL719 and everolimus were not able to inhibit BKM-R cells sufficiently. In addition, there were no changes in ER expression in EDR-1, EDR-2, and MFR cells exposed to PI3Kis for 1 h. Interestingly, ER expression on EDR-2 cells with acquired resistance to PI3Kis was increased compared with that in parental cells.
Conclusion
Our findings showed that PI3Kis exhibited remarkable efficacy in all types of EDR cells, particularly in fulvestrant-resistant cell lines. In PI3Ki- and everolimus-resistant cell lines, BKM120 and BYL719 showed different effects, and BYL719 and everolimus may exhibit cross-resistance. Furthermore, PI3Kis were likely to change the expression of ER.
Citation Format: Tokuda E, Komatsu T, Sasaki S, Tsuboi K, Nakamura M, Iida M, Niwa T, Saito M, Hayashi S-I. Effects of PI3K inhibitors on endocrine-resistant cell lines and differences in the characteristics of ER positive breast cancer cells after acquired resistance to the inhibitors [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-03-12.
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Affiliation(s)
- E Tokuda
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - T Komatsu
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - S Sasaki
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - K Tsuboi
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - M Nakamura
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - M Iida
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - T Niwa
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - M Saito
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
| | - S-I Hayashi
- Tohoku University Graduate School of Medicine, Sendai, Japan; Juntendo University Hospital, Tokyo, Japan
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Iida M, Nakamura M, Tokuda E, Niwa T, Ishida T, Hayashi SI. Abstract P6-04-02: CDK6 might be a key factor for efficacy of CDK4/6 inhibitor and the hormone sensitivity following acquired resistance. Cancer Res 2018. [DOI: 10.1158/1538-7445.sabcs17-p6-04-02] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: CDK4/6 inhibitors have received FDA breakthrough therapy designation as 1st line treatment for advanced estrogen receptor positive breast cancer patients. However, the benefit offered by CDK4/6 inhibitors is individually different and furthermore acquired resistance to the drugs is monumental challenges. It is urgent need to search for the biomarker and understand the drug sensitivity and its alteration after acquired resistance.
Results: To identify the efficacy of CDK4/6 inhibitors, we assessed IC50 of ribociclib in several cell lines. Luminal cell lines (MCF-7, T-47D) exhibited lower ribociclib IC50 than HER-2 (SK-BR-3) and triple negative cell lines (MDA-MB-231, BT-20). Immunoblot analysis of Luminal cell lines showed extremely lower levels of CDK6 compared with others. CDK6-transfected MCF-7 by means of expression vector reduced the sensitivity equivalent to MDA-MB-231 not only to ribociclib but also to palbociclib and abemaciclib. Protein level of ERα in CDK6-transfected MCF-7 stayed unchanged and fulvestrant sensitivity was unaltered as well.
Subsequently, we detect the efficacy of ribociclib in hormone resistant cell lines. Estrogen deprivation-resistant (EDR) cells (EDR1:ER-positive, EDR2:ER-negative) and fulvestrant resistance (MFR) cells (loss of ER expression) established from MCF-7 maintained ribocilib sensitivity to the same degree with MCF-7. No marked difference in IC50 was observed between EDR1/2 and MFR, and CDK6 expressions were comparable to MCF-7. These results suggest that high level of CDK6 expression weaken the sensitivity to CDK4/6 inhibitors. The inhibitors would provide more effective benefits to tumors expressing lower level of CDK6 than the higher, independent of hormone sensitivity.
To understand the characteristics in acquired resistance, ribociclib resistant cell lines (RIBR1/2) were established from EDR1 by long-term culture with ribociclib. RIBR designed lower level of p21, p27 and ERα by immunoblot analysis. EDR1 were promoted cell growth by estrogen addition, while RIBR were not. Further, ER activity of RIBR was intensely decreased, and mRNA levels of the ER target genes, PgR and EGR3 were also decreased. Therefore, the responsiveness to tamoxifen and fulvestrant were lost. On the other hand, PI3K inhibitor and mTOR inhibitor suppressed cell growth to the same extent as EDR1, suggesting that RIBR were reduced ER dependence and remain reliant on PI3K/Akt/mTOR pathway.
Conclusion: The possibility of CDK6 as a biomarker is corroborated by the finding that low level of CDK6 expression is positively correlated with the efficacy of CDK4/6 inhibitor. Further ER dependence had decreased after acquired CDK4/6 inhibitor resistance whereas the dependence on PI3K/Akt/mTOR pathway still remain, indicating the inhibition of PI3K/Akt/mTOR pathway would be amenable to therapeutic target.
Citation Format: Iida M, Nakamura M, Tokuda E, Niwa T, Ishida T, Hayashi S-I. CDK6 might be a key factor for efficacy of CDK4/6 inhibitor and the hormone sensitivity following acquired resistance [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-04-02.
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Affiliation(s)
- M Iida
- Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - M Nakamura
- Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - E Tokuda
- Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - T Niwa
- Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - T Ishida
- Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - S-I Hayashi
- Graduate School of Medicine, Tohoku University, Sendai, Japan
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11
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Fukuoka M, Tokuda E, Nakagome K, Wu Z, Nagano I, Furukawa Y. An essential role of N-terminal domain of copper chaperone in the enzymatic activation of Cu/Zn-superoxide dismutase. J Inorg Biochem 2017; 175:208-216. [DOI: 10.1016/j.jinorgbio.2017.07.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 07/27/2017] [Accepted: 07/28/2017] [Indexed: 10/19/2022]
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12
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Ishiguro T, Sato N, Ueyama M, Fujikake N, Sellier C, Tokuda E, Zamiri B, Gall-Duncan T, Mirceta M, Furukawa Y, Yokota T, Wada K, Taylor P, Pearson C, Charlet-Berguerand N, Mizusawa H, Nagai Y, Ishikawa K. Balance between RNA binding proetin TDP-43 and an RNA UGGAA repeat underlies pathogenesis of spinocerebellar ataxia type 31 (SCA31) and motor neuron disease fly models. J Neurol Sci 2017. [DOI: 10.1016/j.jns.2017.08.218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Ishiguro T, Sato N, Ueyama M, Fujikake N, Sellier C, Kanegami A, Tokuda E, Zamiri B, Gall-Duncan T, Mirceta M, Furukawa Y, Yokota T, Wada K, Taylor JP, Pearson CE, Charlet-Berguerand N, Mizusawa H, Nagai Y, Ishikawa K. Regulatory Role of RNA Chaperone TDP-43 for RNA Misfolding and Repeat-Associated Translation in SCA31. Neuron 2017; 94:108-124.e7. [PMID: 28343865 PMCID: PMC5681996 DOI: 10.1016/j.neuron.2017.02.046] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 10/04/2016] [Accepted: 02/24/2017] [Indexed: 12/20/2022]
Abstract
Microsatellite expansion disorders are pathologically characterized by RNA foci formation and repeat-associated non-AUG (RAN) translation. However, their underlying pathomechanisms and regulation of RAN translation remain unknown. We report that expression of expanded UGGAA (UGGAAexp) repeats, responsible for spinocerebellar ataxia type 31 (SCA31) in Drosophila, causes neurodegeneration accompanied by accumulation of UGGAAexp RNA foci and translation of repeat-associated pentapeptide repeat (PPR) proteins, consistent with observations in SCA31 patient brains. We revealed that motor-neuron disease (MND)-linked RNA-binding proteins (RBPs), TDP-43, FUS, and hnRNPA2B1, bind to and induce structural alteration of UGGAAexp. These RBPs suppress UGGAAexp-mediated toxicity in Drosophila by functioning as RNA chaperones for proper UGGAAexp folding and regulation of PPR translation. Furthermore, nontoxic short UGGAA repeat RNA suppressed mutated RBP aggregation and toxicity in MND Drosophila models. Thus, functional crosstalk of the RNA/RBP network regulates their own quality and balance, suggesting convergence of pathomechanisms in microsatellite expansion disorders and RBP proteinopathies.
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Affiliation(s)
- Taro Ishiguro
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Nozomu Sato
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Morio Ueyama
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan; Department of Neurotherapeutics, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Nobuhiro Fujikake
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, University of Strasbourg, Illkirch 67400, France
| | - Akemi Kanegami
- Research Institute of Biomolecule Metrology, 807-133 Enokido, Tsukuba, Ibaraki 305-0853, Japan
| | - Eiichi Tokuda
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522, Japan
| | - Bita Zamiri
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada; Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Terence Gall-Duncan
- Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Mila Mirceta
- Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Yoshiaki Furukawa
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522, Japan
| | - Takanori Yokota
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Keiji Wada
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - J Paul Taylor
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Christopher E Pearson
- Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Nicolas Charlet-Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, University of Strasbourg, Illkirch 67400, France
| | - Hidehiro Mizusawa
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Yoshitaka Nagai
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan; Department of Neurotherapeutics, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Kinya Ishikawa
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Personalized Medicine for Healthy Aging, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan.
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Anzai I, Tokuda E, Mukaiyama A, Akiyama S, Endo F, Yamanaka K, Misawa H, Furukawa Y. A misfolded dimer of Cu/Zn-superoxide dismutase leading to pathological oligomerization in amyotrophic lateral sclerosis. Protein Sci 2017; 26:484-496. [PMID: 27977888 DOI: 10.1002/pro.3094] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 11/17/2016] [Accepted: 11/21/2016] [Indexed: 12/20/2022]
Abstract
Misfolding of mutant Cu/Zn-superoxide dismutase (SOD1) is a pathological hallmark in a familial form of amyotrophic lateral sclerosis. Pathogenic mutations have been proposed to monomerize SOD1 normally adopting a homodimeric configuration and then trigger abnormal oligomerization of SOD1 proteins. Despite this, a misfolded conformation of SOD1 leading to the oligomerization at physiological conditions still remains ambiguous. Here, we show that, around the body temperature (∼37°C), mutant SOD1 maintains a dimeric configuration but lacks most of its secondary structures. Also, such an abnormal SOD1 dimer with significant structural disorder was prone to irreversibly forming the oligomers crosslinked via disulfide bonds. The disulfide-crosslinked oligomers of SOD1 were detected in the spinal cords of the diseased mice expressing mutant SOD1. We hence propose an alternative pathway of mutant SOD1 misfolding that is responsible for oligomerization in the pathologies of the disease.
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Affiliation(s)
- Itsuki Anzai
- Department of Chemistry, Keio University, Yokohama, 223-8522, Japan
| | - Eiichi Tokuda
- Department of Chemistry, Keio University, Yokohama, 223-8522, Japan
| | - Atsushi Mukaiyama
- Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, NINS, Okazaki, 444-8585, Japan.,Department of Functional Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8585, Japan
| | - Shuji Akiyama
- Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, NINS, Okazaki, 444-8585, Japan.,Department of Functional Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8585, Japan
| | - Fumito Endo
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan
| | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan
| | - Hidemi Misawa
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, 105-8512, Japan
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Tokuda E, Anzai I, Nomura T, Toichi K, Watanabe M, Ohara S, Watanabe S, Yamanaka K, Morisaki Y, Misawa H, Furukawa Y. Immunochemical characterization on pathological oligomers of mutant Cu/Zn-superoxide dismutase in amyotrophic lateral sclerosis. Mol Neurodegener 2017; 12:2. [PMID: 28057013 PMCID: PMC5216565 DOI: 10.1186/s13024-016-0145-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/20/2016] [Indexed: 12/11/2022] Open
Abstract
Background Dominant mutations in Cu/Zn-superoxide dismutase (SOD1) gene cause a familial form of amyotrophic lateral sclerosis (SOD1-ALS) with accumulation of misfolded SOD1 proteins as intracellular inclusions in spinal motor neurons. Oligomerization of SOD1 via abnormal disulfide crosslinks has been proposed as one of the misfolding pathways occurring in mutant SOD1; however, the pathological relevance of such oligomerization in the SOD1-ALS cases still remains obscure. Methods We prepared antibodies exclusively recognizing the SOD1 oligomers cross-linked via disulfide bonds in vitro. By using those antibodies, immunohistochemical examination and ELISA were mainly performed on the tissue samples of transgenic mice expressing mutant SOD1 proteins and also of human SOD1-ALS cases. Results We showed the recognition specificity of our antibodies exclusively toward the disulfide-crosslinked SOD1 oligomers by ELISA using various forms of purified SOD1 proteins in conformationally distinct states in vitro. Furthermore, the epitope of those antibodies was buried and inaccessible in the natively folded structure of SOD1. The antibodies were then found to specifically detect the pathological SOD1 species in the spinal motor neurons of the SOD1-ALS patients as well as the transgenic model mice. Conclusions Our findings here suggest that the SOD1 oligomerization through the disulfide-crosslinking associates with exposure of the SOD1 structural interior and is a pathological process occurring in the SOD1-ALS cases. Electronic supplementary material The online version of this article (doi:10.1186/s13024-016-0145-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Eiichi Tokuda
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa, 223-8522, Japan
| | - Itsuki Anzai
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa, 223-8522, Japan
| | - Takao Nomura
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa, 223-8522, Japan
| | - Keisuke Toichi
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa, 223-8522, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan
| | - Shinji Ohara
- Department of Neurology, Matsumoto Medical Center, Matsumoto, 399-0021, Japan
| | - Seiji Watanabe
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan
| | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan
| | - Yuta Morisaki
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, 105-8512, Japan
| | - Hidemi Misawa
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, 105-8512, Japan
| | - Yoshiaki Furukawa
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa, 223-8522, Japan.
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Anzai I, Toichi K, Tokuda E, Mukaiyama A, Akiyama S, Furukawa Y. Screening of Drugs Inhibiting In vitro Oligomerization of Cu/Zn-Superoxide Dismutase with a Mutation Causing Amyotrophic Lateral Sclerosis. Front Mol Biosci 2016; 3:40. [PMID: 27556028 PMCID: PMC4977284 DOI: 10.3389/fmolb.2016.00040] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/27/2016] [Indexed: 12/14/2022] Open
Abstract
Dominant mutations in Cu/Zn-superoxide dismutase (SOD1) gene have been shown to cause a familial form of amyotrophic lateral sclerosis (SOD1-ALS). A major pathological hallmark of this disease is abnormal accumulation of mutant SOD1 oligomers in the affected spinal motor neurons. While no effective therapeutics for SOD1-ALS is currently available, SOD1 oligomerization will be a good target for developing cures of this disease. Recently, we have reproduced the formation of SOD1 oligomers abnormally cross-linked via disulfide bonds in a test tube. Using our in vitro model of SOD1 oligomerization, therefore, we screened 640 FDA-approved drugs for inhibiting the oligomerization of SOD1 proteins, and three effective classes of chemical compounds were identified. Those hit compounds will provide valuable information on the chemical structures for developing a novel drug candidate suppressing the abnormal oligomerization of mutant SOD1 and possibly curing the disease.
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Affiliation(s)
- Itsuki Anzai
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University Yokohama, Japan
| | - Keisuke Toichi
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University Yokohama, Japan
| | - Eiichi Tokuda
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University Yokohama, Japan
| | - Atsushi Mukaiyama
- Research Center of Integrative Molecular Systems, Institute for Molecular ScienceOkazaki, Japan; Department of Functional Molecular Science, SOKENDAI (The Graduate University for Advanced Studies)Okazaki, Japan
| | - Shuji Akiyama
- Research Center of Integrative Molecular Systems, Institute for Molecular ScienceOkazaki, Japan; Department of Functional Molecular Science, SOKENDAI (The Graduate University for Advanced Studies)Okazaki, Japan
| | - Yoshiaki Furukawa
- Laboratory for Mechanistic Chemistry of Biomolecules, Department of Chemistry, Keio University Yokohama, Japan
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Tokuda E, Brännström T, Andersen PM, Marklund SL. Low autophagy capacity implicated in motor system vulnerability to mutant superoxide dismutase. Acta Neuropathol Commun 2016; 4:6. [PMID: 26810478 PMCID: PMC4727314 DOI: 10.1186/s40478-016-0274-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 01/09/2016] [Indexed: 11/10/2022] Open
Abstract
Introduction The motor system is selectively vulnerable to mutations in the ubiquitously expressed aggregation-prone enzyme superoxide dismutase-1 (SOD1). Results Autophagy clears aggregates, and factors involved in the process were analyzed in multiple areas of the CNS from human control subjects (n = 10) and amyotrophic lateral sclerosis (ALS) patients (n = 18) with or without SOD1 mutations. In control subjects, the key regulatory protein Beclin 1 and downstream factors were remarkably scarce in spinal motor areas. In ALS patients, there was evidence of moderate autophagy activation and also dysregulation. These changes were largest in SOD1 mutation carriers. To explore consequences of low autophagy capacity, effects of a heterozygous deletion of Beclin 1 were examined in ALS mouse models expressing mutant SOD1s. This caused earlier SOD1 aggregation, onset of symptoms, motor neuron loss, and a markedly shortened survival. In contrast, the levels of soluble misfolded SOD1 species were reduced. Conclusions The findings suggest that an inherent low autophagy capacity might cause the vulnerability of the motor system, and that SOD1 aggregation plays a crucial role in the pathogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s40478-016-0274-y) contains supplementary material, which is available to authorized users.
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Tokuda E, Watanabe S, Okawa E, Ono SI. Regulation of Intracellular Copper by Induction of Endogenous Metallothioneins Improves the Disease Course in a Mouse Model of Amyotrophic Lateral Sclerosis. Neurotherapeutics 2015; 12:461-76. [PMID: 25761970 PMCID: PMC4404437 DOI: 10.1007/s13311-015-0346-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mutations in SOD1 cause amyotrophic lateral sclerosis (ALS), an incurable motor neuron disease. The pathogenesis of the disease is poorly understood, but intracellular copper dyshomeostasis has been implicated as a key process in the disease. We recently observed that metallothioneins (MTs) are an excellent target for the modification of copper dyshomeostasis in a mouse model of ALS (SOD1(G93A)). Here, we offer a therapeutic strategy designed to increase the level of endogenous MTs. The upregulation of endogenous MTs by dexamethasone, a synthetic glucocorticoid, significantly improved the disease course and rescued motor neurons in SOD1(G93A) mice, even if the induction was initiated when peak body weight had decreased by 10%. Neuroprotection was associated with the normalization of copper dyshomeostasis, as well as with decreased levels of SOD1(G93A) aggregates. Importantly, these benefits were clearly mediated in a MT-dependent manner, as dexamethasone did not provide any protection when endogenous MTs were abolished from SOD1(G93A) mice. In conclusion, the upregulation of endogenous MTs represents a promising strategy for the treatment of ALS linked to mutant SOD1.
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Affiliation(s)
- Eiichi Tokuda
- />Laboratory of Clinical Medicine, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi, Chiba 274-8555 Japan
- />Department of Medical Biosciences, Clinical Chemistry, Umeå University, Building 6M, 2nd Floor, Umeå, 901-85 Sweden
| | - Shunsuke Watanabe
- />Laboratory of Clinical Medicine, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi, Chiba 274-8555 Japan
| | - Eriko Okawa
- />Laboratory of Clinical Medicine, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi, Chiba 274-8555 Japan
| | - Shin-ichi Ono
- />Laboratory of Clinical Medicine, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi, Chiba 274-8555 Japan
- />Division of Neurology, Akiru Municipal Medical Center, 78-1 Hikida, Akiru, Tokyo, 197-0834 Japan
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Tokuda E, Okawa E, Watanabe S, Ono SI. Overexpression of metallothionein-I, a copper-regulating protein, attenuates intracellular copper dyshomeostasis and extends lifespan in a mouse model of amyotrophic lateral sclerosis caused by mutant superoxide dismutase-1. Hum Mol Genet 2013; 23:1271-85. [PMID: 24163136 DOI: 10.1093/hmg/ddt517] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Over 170 mutations in superoxide dismutase-1 (SOD1) cause familial amyotrophic lateral sclerosis (ALS), a lethal motor neuron disease. Although the molecular properties of SOD1 mutants differ considerably, we have recently shown that intracellular copper dyshomeostasis is a common pathogenic feature of different SOD1 mutants. Thus, the potentiation of endogenous copper regulation could be a therapeutic strategy. In this study, we investigated the effects of the overexpression of metallothionein-I (MT-I), a major copper-regulating protein, on the disease course of a mouse model of ALS (SOD1(G93A)). Using double transgenic techniques, we found that the overexpression of MT-I in SOD1(G93A) mice significantly extended the lifespan and slowed disease progression, but the effects on disease onset were modest. Genetically induced MT-I normalized copper dyshomeostasis in the spinal cord without influencing SOD1 enzymatic activity. The overexpression of MT-I in SOD1(G93A) mice markedly attenuated the pathological features of the mice, including the death of motor neurons, the degeneration of ventral root axons, the atrophy of skeletal muscles, and the activation of glial cells. Double transgenic mice also showed a decreased level of SOD1 aggregates within the glial cells of the spinal cord. Furthermore, the overexpression of MT-I in SOD1(G93A) mice reduced the number of spheroid-shaped astrocytes cleaved by active caspase-3. We concluded that therapeutic strategies aimed at the potentiation of copper regulation by MT-I could be of benefit in cases of ALS caused by SOD1 mutations.
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Affiliation(s)
- Eiichi Tokuda
- Laboratory of Clinical Medicine, School of Pharmacy, Nihon University, 7-7-1, Narashinodai, Funabashi, Chiba 274-8555, Japan
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Tokuda E, Okawa E, Watanabe S, Ono SI, Marklund SL. Dysregulation of intracellular copper homeostasis is common to transgenic mice expressing human mutant superoxide dismutase-1s regardless of their copper-binding abilities. Neurobiol Dis 2013; 54:308-19. [PMID: 23321002 DOI: 10.1016/j.nbd.2013.01.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 12/19/2012] [Accepted: 01/04/2013] [Indexed: 10/27/2022] Open
Abstract
Over 170 mutations in superoxide dismutase-1 (SOD1) have been linked to amyotrophic lateral sclerosis (ALS). The properties of SOD1 mutants differ considerably including copper-binding abilities. Nevertheless, they cause the same disease phenotype, suggesting a common neurotoxic pathway. We have previously reported that copper homeostasis is disturbed in spinal cords of SOD1(G93A) mice. However, it is unknown whether copper dyshomeostasis is induced by other SOD1 mutants. Using the additional mouse strains SOD1(G127insTGGG), SOD1(G85R), and SOD1(D90A), which express SOD1 mutants with different copper-binding abilities, we show that copper dyshomeostasis is common to SOD1 mutants. The SOD1 mutants shifted the copper trafficking systems toward copper accumulation in spinal cords of the mice. Copper contents bound to the SOD1 active site varied considerably between SOD1 mutants. Still, copper bound to other ligands in the spinal cord were markedly increased in all. Zinc was also increased, whereas there were no changes in magnesium, calcium, aluminum, manganese and iron. Further support for a role of copper dyshomeostasis in ALS was gained from results of pharmacological intervention. Ammonium tetrathiomolybdate (TTM), a copper chelating agent, prolonged survival and slowed the disease progression of SOD1(G93A) mice, even when the treatment was started after the disease onset. TTM markedly attenuated pathology, including the loss of motor neurons and axons, and atrophy of skeletal muscles. Additionally, TTM decreased amounts of SOD1 aggregates. We propose that pharmacological agents that are capable of modulating copper dyshomeostasis, such as TTM, might be beneficial for the treatment of ALS caused by SOD1 mutations.
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Affiliation(s)
- Eiichi Tokuda
- Department of Medical Biosciences, Clinical Chemistry, Umeå University, Building 6M, Umeå, SE 901 85, Sweden
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Horimoto Y, Tokuda E, Senuma K, Yimit A, Arakawa A, Mitomi H, Saito M. 437 Relevance of Primary Systemic Chemotherapy in &;ldquo;Luminal A” Breast Cancer. Eur J Cancer 2012. [DOI: 10.1016/s0959-8049(12)70503-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Tomiyama S, Tokuda E, Miura H, Saito M, Kasumi F. P148 Breast cancer among the young and elderly populations in Japan: Which differences can be seen? Breast 2011. [DOI: 10.1016/s0960-9776(11)70091-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Horimoto Y, Tokuda E, Shiraishi A, Nakagawa T, Kosaka T, Saito M, Kasumi F. 557 Validity of follow-up bone scan in symptom-free patients with breast cancer. EJC Suppl 2010. [DOI: 10.1016/s1359-6349(10)70578-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Tokuda E, Okawa E, Ono SI. Dysregulation of intracellular copper trafficking pathway in a mouse model of mutant copper/zinc superoxide dismutase-linked familial amyotrophic lateral sclerosis. J Neurochem 2009; 111:181-91. [PMID: 19656261 DOI: 10.1111/j.1471-4159.2009.06310.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mutations in copper/zinc superoxide dismutase (SOD1) are responsible for 20% of familial amyotrophic lateral sclerosis through a gain-of-toxic function. We have recently shown that ammonium tetrathiomolybdate, an intracellular copper-chelating reagent, has an excellent therapeutic benefit in a mouse model for amyotrophic lateral sclerosis. This finding suggests that mutant SOD1 might disrupt intracellular copper homeostasis. In this study, we investigated the effects of mutant SOD1 on the components of the copper trafficking pathway, which regulate intracellular copper homeostasis. We found that mutant, but not wild-type, SOD1 shifts intracellular copper homeostasis toward copper accumulation in the spinal cord during disease progression: copper influx increases, copper chaperones are up-regulated, and copper efflux decreases. This dysregulation was observed within spinal motor neurons and was proportionally associated with an age-dependent increase in spinal copper ion levels. We also found that a subset of the copper trafficking pathway constituents co-aggregated with mutant SOD1. These results indicate that the nature of mutant SOD1 toxicity might involve the dysregulation of the copper trafficking pathway, resulting in the disruption of intracellular copper homeostasis.
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Affiliation(s)
- Eiichi Tokuda
- Research Unit of Clinical Pharmacy, College of Pharmacy, Nihon University, Tokyo, Japan
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Tokuda E, Ono SI, Ishige K, Watanabe S, Okawa E, Ito Y, Suzuki T. Dysequilibrium between caspases and their inhibitors in a mouse model for amyotrophic lateral sclerosis. Brain Res 2007; 1148:234-42. [PMID: 17397813 DOI: 10.1016/j.brainres.2007.02.087] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 02/14/2007] [Accepted: 02/14/2007] [Indexed: 11/28/2022]
Abstract
Mutations in copper/zinc superoxide dismutase (SOD1) have been implicated in the pathogenesis of familial amyotrophic lateral sclerosis (ALS). Mutant SOD1 protein likely gains a novel cytotoxic property, leading to the death of motor neurons. We therefore investigated whether caspase-mediated apoptosis is associated with novel cytotoxic properties in a rodent model for familial ALS (G93A SOD1 transgenic mice). Caspase-9 (an effecter in the mitochondrial apoptotic pathway), caspase-8 (an effecter in the Fas apoptotic pathway), and caspase-3 (an executioner of both pathways) proteins were all present in nonactive forms in the spinal cords of wild-type mice during the early stage of the disease (8 weeks), at which time the mice had not yet exhibited motor paralysis. In transgenic mice, however, these proteins were present in their active forms, and their mRNA levels were significantly upregulated in the represent to this conversion from nonactive to active forms. During the advanced stage of the disease (16 weeks), when paralysis was evident, the active caspase levels were further elevated. On the other hand, the mRNA and protein levels of survivin, a counteraction protein against caspases, were significantly suppressed during the early stage, and sharply increased during the advanced stage. Although the mRNA and protein levels of X-linked inhibitor of apoptosis protein (XIAP) remained at the same levels as those seen in the control (wild-type mice) during the early stage, they were significantly depressed at an age of 16 weeks. These findings were observed exclusively in the spinal cord, the region responsible for the disease, and not in the cerebellum, a non-responsible region. We conclude that conditions facilitating the apoptotic process during the early stage of the disease play causative roles in the pathogenesis of ALS and that the suppression of XIAP levels during the advanced stage could contribute to disease expression and/or progression.
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Affiliation(s)
- Eiichi Tokuda
- Research Unit of Clinical Pharmacy, College of Pharmacy, Nihon University, 7-7-1, Narashinodai, Funabashi, Chiba, 274-8555, Japan
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Tokuda E, Ono SI, Ishige K, Naganuma A, Ito Y, Suzuki T. Metallothionein proteins expression, copper and zinc concentrations, and lipid peroxidation level in a rodent model for amyotrophic lateral sclerosis. Toxicology 2007; 229:33-41. [PMID: 17097207 DOI: 10.1016/j.tox.2006.09.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 09/06/2006] [Accepted: 09/24/2006] [Indexed: 11/28/2022]
Abstract
It has been hypothesized that copper-mediated oxidative stress contributes to the pathogenesis of familial amyotrophic lateral sclerosis (ALS), a fatal motor neuron disease in humans. To verify this hypothesis, we examined the copper and zinc concentrations and the amounts of lipid peroxides, together with that of the expression of metallothionein (MT) isoforms in a mouse model [superoxide dismutase1 transgenic (SOD1 Tg) mouse] of ALS. The expression of MT-I and MT-II (MT-I/II) isoforms were measured together with Western blotting, copper level, and lipid peroxides amounts increased in an age-dependent manner in the spinal cord, the region responsible for motor paralysis. A significant increase was already seen as early as 8-week-old SOD1 Tg mice, at which time the mice had not yet exhibited motor paralysis, and showed a further increase at 16 weeks of age, when paralysis was evident. Inversely, the spinal zinc level had significantly decreased at both 8 and 16 weeks of age. The third isoform, the MT-III level, remained at the same level as an 8-week-old wild-type mouse, finally increasing to a significant level at 16 weeks of age. It has been believed that a mutant SOD1 protein, encoded by a mutant SOD1, gains a novel cytotoxic function while maintaining its original enzymatic activity, and causes motor neuron death (gain-of-toxic function). Copper-mediated oxidative stress seems to be a probable underlying pathogenesis of gain-of-toxic function. Taking the above current concepts and the classic functions of MT into account, MTs could have a disease modifying property: the MT-I/II isoform for attenuating the gain-of-toxic function at the early stage of the disease, and the MT-III isoform at an advanced stage.
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Affiliation(s)
- Eiichi Tokuda
- Laboratory of Clinical Pharmacy, College of Pharmacy, Nihon University, Chiba, Japan
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