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Yin T, Yesiltepe M, D'Adamio L. Functional BRI2-TREM2 interactions in microglia: implications for Alzheimer's and related dementias. EMBO Rep 2024; 25:1326-1360. [PMID: 38347225 PMCID: PMC10933458 DOI: 10.1038/s44319-024-00077-x] [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: 07/13/2023] [Revised: 01/17/2024] [Accepted: 01/19/2024] [Indexed: 03/14/2024] Open
Abstract
ITM2B/BRI2 mutations cause Alzheimer's Disease (AD)-related dementias. We observe heightened ITM2B/BRI2 expression in microglia, a pivotal cell type in AD due to risk-increasing variants in the microglial gene TREM2. Single-cell RNA-sequencing demonstrates a Trem2/Bri2-dependent microglia cluster, underscoring their functional interaction. α-secretase cleaves TREM2 into TREM2-CTF and sTREM2. As BRI2 hinders α-secretase cleavage of the AD-related Aβ-Precursor-Protein, we probed whether BRI2 influences TREM2 processing. Our findings indicate a BRI2-TREM2 interaction that inhibits TREM2 processing in heterologous cells. Recombinant BRI2 and TREM2 proteins demonstrate a direct, cell-free BRI2-TREM2 ectodomain interaction. Constitutive and microglial-specific Itm2b-Knock-out mice, and Itm2b-Knock-out primary microglia provide evidence that Bri2 reduces Trem2 processing, boosts Trem2 mRNA expression, and influences Trem2 protein levels through α-secretase-independent pathways, revealing a multifaceted BRI2-TREM2 functional interaction. Moreover, a mutant Itm2b dementia mouse model exhibits elevated Trem2-CTF and sTrem2, mirroring sTREM2 increases in AD patients. Lastly, Bri2 deletion reduces phagocytosis similarly to a pathogenic TREM2 variant that enhances processing. Given BRI2's role in regulating Aβ-Precursor-Protein and TREM2 functions, it holds promise as a therapeutic target for AD and related dementias.
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Affiliation(s)
- Tao Yin
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 205 South Orange Ave, Newark, NJ, 07103, USA.
| | - Metin Yesiltepe
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 205 South Orange Ave, Newark, NJ, 07103, USA.
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Yin T, D’Adamio L. BRI2-mediated regulation of TREM2 processing in microglia and its potential implications for Alzheimer's disease and related dementias. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.14.544924. [PMID: 37398330 PMCID: PMC10312752 DOI: 10.1101/2023.06.14.544924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
ITM2B/BRI2 mutations cause familial forms of Alzheimer's disease (AD)-related dementias by disrupting BRI2's protein function and leading to the accumulation of amyloidogenic peptides. Although typically studied in neurons, our findings show that BRI2 is highly expressed in microglia, which are crucial in AD pathogenesis due to the association of variants in the microglial gene TREM2 with increased AD risk. Our single-cell RNAseq (scRNAseq) analysis revealed a microglia cluster that depends on a Trem2 activity that is inhibited by Bri2, pointing to a functional interaction between Itm2b/Bri2 and Trem2. Given that the AD-related Amyloid-β Precursor protein (APP) and TREM2 undergo similar proteolytic processing, and that BRI2 inhibits APP processing, we hypothesized that BRI2 may also regulate TREM2 processing. We found that BRI2 interacts with Trem2 and inhibits its processing by α-secretase in transfected cells. In mice lacking Bri2 expression, we observed increased central nervous system (CNS) levels of Trem2-CTF and sTrem2, which are the products of α-secretase processing of Trem2, indicating increased Trem2 processing by α-secretase in vivo. Reducing Bri2 expression only in microglia resulted in increased sTrem2 levels, suggesting a cell-autonomous effect of Bri2 on α-secretase processing of Trem2. Our study reveals a previously unknow role of BRI2 in regulating TREM2-related neurodegenerative mechanisms. The ability of BRI2 to regulate the processing of both APP and TREM2, combined with its cell-autonomous role in neurons and microglia, makes it a promising candidate for the development of AD and AD-related dementias therapeutics.
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Affiliation(s)
- Tao Yin
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer’s Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Luciano D’Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer’s Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 205 South Orange Ave, Newark, NJ, 07103, USA
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Abstract
Neurodegenerative diseases are characterized by the progressive loss of structure or function of neurons. In this Spotlight, we explore the idea that genetic forms of neurodegenerative disorders might be rooted in neural development. Focusing on Alzheimer's, Parkinson's and Huntington's disease, we first provide a brief overview of the pathology for these diseases. Although neurodegenerative diseases are generally thought of as late-onset diseases, we discuss recent evidence promoting the notion that they might be considered neurodevelopmental disorders. With this view in mind, we consider the suitability of animal models for studying these diseases, highlighting human-specific features of human brain development. We conclude by proposing that one such feature, human-specific regulation of neurogenic time, might be key to understanding the etiology and pathophysiology of human neurodegenerative disease.
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Affiliation(s)
- Khadijeh Shabani
- Institut du Cerveau – Paris Brain Institute – ICM, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, 75013 Paris, France
| | - Bassem A. Hassan
- Institut du Cerveau – Paris Brain Institute – ICM, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, 75013 Paris, France
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Rhyu JM, Park J, Shin BS, Kim YE, Kim EJ, Kim KW, Cho YG. A Novel c.800G>C Variant of the ITM2B Gene in Familial Korean Dementia. J Alzheimers Dis 2023; 93:403-409. [PMID: 37038821 DOI: 10.3233/jad-230051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Mutations in ITM2B have been reported to be associated with several familial dementias, such as Familial British dementia and familial Danish dementia. These are autosomal dominant disorders characterized by progressive dementia with an onset at around the fifth decade of life. We describe a family with cognitive impairment caused by a novel ITM2B p.*267Serext*11 mutation. The probands presented with cognitive impairment and cerebral infarction. MRI revealed diffuse white matter hyperintensity and microbleeds. Amyloid deposition was not observed on amyloid positron emission tomography. Our case suggests that the BRI2 mutation impacts cognition regardless of amyloid-β accumulation.
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Affiliation(s)
- Jee-Min Rhyu
- Department of Neurology, Jeonbuk National University Medical School and Hospital, Jeonju, Korea
| | - Joonhong Park
- Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju, Korea
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Korea
| | - Byoung-Soo Shin
- Department of Neurology, Jeonbuk National University Medical School and Hospital, Jeonju, Korea
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Korea
| | - Young-Eun Kim
- Department of Laboratory Medicine, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Eun-Joo Kim
- Department of Neurology, Pusan National University Hospital, Busan, South Korea
| | - Ko Woon Kim
- Department of Neurology, Jeonbuk National University Medical School and Hospital, Jeonju, Korea
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Korea
| | - Yong Gon Cho
- Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju, Korea
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Korea
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5
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Pham H, Yin T, D’Adamio L. Initial assessment of the spatial learning, reversal, and sequencing task capabilities of knock-in rats with humanizing mutations in the Aβ-coding region of App. PLoS One 2022; 17:e0263546. [PMID: 35507596 PMCID: PMC9067689 DOI: 10.1371/journal.pone.0263546] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 04/21/2022] [Indexed: 11/30/2022] Open
Abstract
Model organisms mimicking the pathogenesis of human diseases are useful for identifying pathogenic mechanisms and testing therapeutic efficacy of compounds targeting them. Models of Alzheimer's disease (AD) and related dementias (ADRD) aim to reproduce the brain pathology associated with these neurodegenerative disorders. Transgenic models, which involve random insertion of disease-causing genes under the control of artificial promoters, are efficient means of doing so. There are confounding factors associated with transgenic approaches, however, including target gene overexpression, dysregulation of endogenous gene expression at transgenes' integration sites, and limitations in mimicking loss-of-function mechanisms. Furthermore, the choice of species is important, and there are anatomical, physiological, and cognitive reasons for favoring the rat over the mouse, which has been the standard for models of neurodegeneration and dementia. We report an initial assessment of the spatial learning, reversal, and sequencing task capabilities of knock-in (KI) Long-Evans rats with humanizing mutations in the Aβ-coding region of App, which encodes amyloid precursor protein (Apph/h rats), using the IntelliCage, an automated operant social home cage system, at 6-8 weeks of age, then again at 4-5 months of age. These rats were previously generated as control organisms for studies on neurodegeneration involving other knock-in rat models from our lab. Apph/h rats of either sex can acquire place learning and reversal tasks. They can also acquire a diagonal sequencing task by 6-8 weeks of age, but not a more advanced serial reversal task involving alternating diagonals, even by 4-5 months of age. Thus, longitudinal behavioral analysis with the IntelliCage system can be useful to determine, in follow-up studies, whether KI rat models of Familial AD (FAD), sporadic late onset AD (LOAD), and of ADRD develop aging-dependent learning and memory deficits.
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Affiliation(s)
- Hoa Pham
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer’s Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, NJ, United States of America
| | - Tao Yin
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer’s Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, NJ, United States of America
| | - Luciano D’Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer’s Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, NJ, United States of America
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Gharibyan AL, Wasana Jayaweera S, Lehmann M, Anan I, Olofsson A. Endogenous Human Proteins Interfering with Amyloid Formation. Biomolecules 2022; 12:biom12030446. [PMID: 35327638 PMCID: PMC8946693 DOI: 10.3390/biom12030446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/08/2022] [Accepted: 03/11/2022] [Indexed: 01/09/2023] Open
Abstract
Amyloid formation is a pathological process associated with a wide range of degenerative disorders, including Alzheimer’s disease, Parkinson’s disease, and diabetes mellitus type 2. During disease progression, abnormal accumulation and deposition of proteinaceous material are accompanied by tissue degradation, inflammation, and dysfunction. Agents that can interfere with the process of amyloid formation or target already formed amyloid assemblies are consequently of therapeutic interest. In this context, a few endogenous proteins have been associated with an anti-amyloidogenic activity. Here, we review the properties of transthyretin, apolipoprotein E, clusterin, and BRICHOS protein domain which all effectively interfere with amyloid in vitro, as well as displaying a clinical impact in humans or animal models. Their involvement in the amyloid formation process is discussed, which may aid and inspire new strategies for therapeutic interventions.
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Affiliation(s)
- Anna L. Gharibyan
- Department of Clinical Microbiology, Umeå University, 901 87 Umeå, Sweden;
- Correspondence: (A.L.G.); (A.O.)
| | | | - Manuela Lehmann
- Department of Public Health and Clinical Medicine, Umeå University, 901 87 Umeå, Sweden; (M.L.); (I.A.)
| | - Intissar Anan
- Department of Public Health and Clinical Medicine, Umeå University, 901 87 Umeå, Sweden; (M.L.); (I.A.)
| | - Anders Olofsson
- Department of Clinical Microbiology, Umeå University, 901 87 Umeå, Sweden;
- Correspondence: (A.L.G.); (A.O.)
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Martins F, Santos I, da Cruz E Silva OAB, Tambaro S, Rebelo S. The role of the integral type II transmembrane protein BRI2 in health and disease. Cell Mol Life Sci 2021; 78:6807-6822. [PMID: 34480585 PMCID: PMC11072861 DOI: 10.1007/s00018-021-03932-5] [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: 05/18/2021] [Revised: 08/07/2021] [Accepted: 08/26/2021] [Indexed: 10/20/2022]
Abstract
BRI2 is a type II transmembrane protein ubiquitously expressed whose physiological function remains poorly understood. Although several recent important advances have substantially impacted on our understanding of BRI2 biology and function, providing valuable information for further studies on BRI2. These findings have contributed to a better understanding of BRI2 biology and the underlying signaling pathways involved. In turn, these might provide novel insights with respect to neurodegeneration processes inherent to BRI2-related pathologies, namely Familial British and Danish dementias, Alzheimer's disease, ITM2B-related retinal dystrophy, and multiple sclerosis. In this review, we provided a state-of-the-art outline of BRI2 biology, both in physiological and pathological conditions, and discuss the proposed molecular underlying mechanisms. Overall, the BRI2 knowledge here reviewed is of extreme importance and may contribute to propose BRI2 and/or BRI2 proteolytic fragments as novel therapeutic targets for neurodegenerative diseases, such as Alzheimer's disease.
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Affiliation(s)
- Filipa Martins
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal.
| | - Isabela Santos
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Odete A B da Cruz E Silva
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Simone Tambaro
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, 141 83, Huddinge, Sweden.
| | - Sandra Rebelo
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal.
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8
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A familial Danish dementia rat shows impaired presynaptic and postsynaptic glutamatergic transmission. J Biol Chem 2021; 297:101089. [PMID: 34416235 PMCID: PMC8429969 DOI: 10.1016/j.jbc.2021.101089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 11/20/2022] Open
Abstract
Familial British dementia and familial Danish dementia are neurodegenerative disorders caused by mutations in the gene integral membrane protein 2B (ITM2b) encoding BRI2, which tunes excitatory synaptic transmission at both presynaptic and postsynaptic termini. In addition, BRI2 interacts with and modulates proteolytic processing of amyloid-β precursor protein (APP), whose mutations cause familial forms of Alzheimer's disease (AD) (familial AD). To study the pathogenic mechanisms triggered by the Danish mutation, we generated rats carrying the Danish mutation in the rat Itm2b gene (Itm2bD rats). Given the BRI2/APP interaction and the widely accepted relevance of human amyloid β (Aβ), a proteolytic product of APP, to AD, Itm2bD rats were engineered to express two humanized App alleles and produce human Aβ. Here, we studied young Itm2bD rats to investigate early pathogenic changes in these diseases. We found that periadolescent Itm2bD rats not only present subtle changes in human Aβ levels along with decreased spontaneous glutamate release and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor–mediated responses but also had increased short-term synaptic facilitation in the hippocampal Schaeffer-collateral pathway. These alterations in excitatory interneuronal communication can impair learning and memory processes and were akin to those observed in adult mice producing rodent Aβ and carrying either the Danish or British mutations in the mouse Itm2b gene. Collectively, the data show that the pathogenic Danish mutation alters the physiological function of BRI2 at glutamatergic synapses across species and early in life. Future studies will determine whether this phenomenon represents an early pathogenic event in human dementia.
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9
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Yasukawa T, Tsutsui A, Tomomori-Sato C, Sato S, Saraf A, Washburn MP, Florens L, Terada T, Shimizu K, Conaway RC, Conaway JW, Aso T. NRBP1-Containing CRL2/CRL4A Regulates Amyloid β Production by Targeting BRI2 and BRI3 for Degradation. Cell Rep 2021; 30:3478-3491.e6. [PMID: 32160551 DOI: 10.1016/j.celrep.2020.02.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 12/09/2019] [Accepted: 02/13/2020] [Indexed: 11/18/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease caused by accumulations of Aβ peptides. Production and fibrillation of Aβ are downregulated by BRI2 and BRI3, which are physiological inhibitors of amyloid precursor protein (APP) processing and Aβ oligomerization. Here, we identify nuclear receptor binding protein 1 (NRBP1) as a substrate receptor of a Cullin-RING ubiquitin ligase (CRL) that targets BRI2 and BRI3 for degradation. Moreover, we demonstrate that (1) dimerized NRBP1 assembles into a functional Cul2- and Cul4A-containing heterodimeric CRL through its BC-box and an overlapping cryptic H-box, (2) both Cul2 and Cul4A contribute to NRBP1 CRL function, and (3) formation of the NRBP1 heterodimeric CRL is strongly enhanced by chaperone-like function of TSC22D3 and TSC22D4. NRBP1 knockdown in neuronal cells results in an increase in the abundance of BRI2 and BRI3 and significantly reduces Aβ production. Thus, disrupting interactions between NRBP1 and its substrates BRI2 and BRI3 may provide a useful therapeutic strategy for AD.
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Affiliation(s)
- Takashi Yasukawa
- Department of Functional Genomics, Kochi Medical School, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan
| | - Aya Tsutsui
- Department of Functional Genomics, Kochi Medical School, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan
| | | | - Shigeo Sato
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Anita Saraf
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Michael P Washburn
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Pathology and Laboratory Medicine, Kansas University Medical Center, Kansas City, KS 66160, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Tohru Terada
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Agricultural Bioinformatics Research Unit, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kentaro Shimizu
- Agricultural Bioinformatics Research Unit, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ronald C Conaway
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Biochemistry and Molecular Biology, Kansas University Medical Center, Kansas City, KS 66160, USA
| | - Joan W Conaway
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Biochemistry and Molecular Biology, Kansas University Medical Center, Kansas City, KS 66160, USA
| | - Teijiro Aso
- Department of Functional Genomics, Kochi Medical School, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan.
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Ren S, Breuillaud L, Yao W, Yin T, Norris KA, Zehntner SP, D'Adamio L. TNF-α-mediated reduction in inhibitory neurotransmission precedes sporadic Alzheimer's disease pathology in young Trem2 R47H rats. J Biol Chem 2021; 296:100089. [PMID: 33434745 PMCID: PMC7949092 DOI: 10.1074/jbc.ra120.016395] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/14/2020] [Accepted: 11/16/2020] [Indexed: 12/31/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative dementia associated with deposition of amyloid plaques and neurofibrillary tangles, formed by amyloid β (Aβ) peptides and phosphor-tau, respectively, in the central nervous system. Approximately 2% of AD cases are due to familial AD (FAD); ∼98% of cases are sporadic AD (SAD). Animal models with FAD are commonly used to study SAD pathogenesis. Because mechanisms leading to FAD and SAD may be distinct, to study SAD pathogenesis, we generated Trem2R47H knock-in rats, which carry the SAD risk factor p.R47H variant of the microglia gene triggering receptor expressed on myeloid cells 2 (TREM2). Trem2R47H rats produce human-Aβ from a humanized-App rat allele because human-Aβ is more toxic than rodent-Aβ and the pathogenic role of the p.R47H TREM2 variant has been linked to human-Aβ-clearing deficits. Using periadolescent Trem2R47H rats, we previously demonstrated that supraphysiological tumor necrosis factor-α (TNF-α) boosts glutamatergic transmission, which is excitatory, and suppresses long-term potentiation, a surrogate of learning and memory. Here, we tested the effect of the p.R47H variant on the inhibitory neurotransmitter γ-aminobutyric acid. We report that GABAergic transmission is decreased in Trem2R47H/R47H rats. This decrease is due to acute and reversible action of TNF-α and is not associated with increased human-Aβ levels and AD pathology. Thus, the p.R47H variant changes the excitatory/inhibitory balance, favoring excitation. This imbalance could potentiate glutamate excitotoxicity and contribute to neuronal dysfunction, enhanced neuronal death, and neurodegeneration. Future studies will determine whether this imbalance represents an early, Aβ-independent pathway leading to dementia and may reveal the AD-modifying therapeutic potential of TNF-α inhibition in the central nervous system.
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Affiliation(s)
- Siqiang Ren
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA
| | | | - Wen Yao
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA
| | - Tao Yin
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA
| | - Kelly A Norris
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA
| | | | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA.
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11
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Yin T, Yao W, Lemenze AD, D'Adamio L. Danish and British dementia ITM2b/BRI2 mutations reduce BRI2 protein stability and impair glutamatergic synaptic transmission. J Biol Chem 2020; 296:100054. [PMID: 33172889 PMCID: PMC7948410 DOI: 10.1074/jbc.ra120.015679] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 12/31/2022] Open
Abstract
Mutations in integral membrane protein 2B (ITM2b/BRI2) gene cause familial British and Danish dementia (FBD and FDD), autosomal dominant disorders characterized by progressive cognitive deterioration. Two pathogenic mechanisms, which may not be mutually exclusive, have been proposed for FDD and FBD: 1) loss of BRI2 function; 2) accumulation of amyloidogenic mutant BRI2-derived peptides, but the mechanistic details remain unclear. We have previously reported a physiological role of BRI2 in excitatory synaptic transmission at both presynaptic termini and postsynaptic termini. To test whether pathogenic ITM2b mutations affect these physiological BRI2 functions, we analyzed glutamatergic transmission in FDD and FBD knock-in mice, which carry pathogenic FDD and FBD mutations into the mouse endogenous Itm2b gene. We show that in both mutant lines, spontaneous glutamate release and AMPAR-mediated responses are decreased, while short-term synaptic facilitation is increased, effects similar to those observed in Itm2bKO mice. In vivo and in vitro studies show that both pathogenic mutations alter maturation of BRI2 resulting in reduced levels of functional mature BRI2 protein at synapses. Collectively, the data show that FDD and FBD mutations cause a reduction of BRI2 levels and function at synapses, which results in reduced glutamatergic transmission. Notably, other genes mutated in Familial dementia, such as APP, PSEN1/PSEN2, are implicated in glutamatergic synaptic transmission, a function that is altered by pathogenic mutations. Thus, defects in excitatory neurotransmitter release may represent a general and convergent mechanism leading to neurodegeneration. Targeting these dysfunction may offer a unique disease modifying method of therapeutic intervention in neurodegenerative disorders.
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Affiliation(s)
- Tao Yin
- Department of Pharmacology, Physiology & Neuroscience, New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA
| | - Wen Yao
- Department of Pharmacology, Physiology & Neuroscience, New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA
| | - Alexander D Lemenze
- Department of Pathology, Immunology, and Laboratory Medicine, New Jersey Medical School, The State University of New Jersey, Newark, New Jersey, USA
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience, New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, New Jersey, USA.
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Ren S, Yao W, Tambini MD, Yin T, Norris KA, D'Adamio L. Microglia TREM2R47H Alzheimer-linked variant enhances excitatory transmission and reduces LTP via increased TNF-α levels. eLife 2020; 9:57513. [PMID: 32579116 PMCID: PMC7338048 DOI: 10.7554/elife.57513] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/23/2020] [Indexed: 01/09/2023] Open
Abstract
To study the mechanisms by which the p.R47H variant of the microglia gene and Alzheimer’s disease (AD) risk factor TREM2 increases dementia risk, we created Trem2R47H KI rats. Trem2R47H rats were engineered to produce human Aβ to define human-Aβ-dependent and -independent pathogenic mechanisms triggered by this variant. Interestingly, pre- and peri-adolescent Trem2R47H rats present increased brain concentrations of TNF-α, augmented glutamatergic transmission, suppression of Long-term-Potentiation (LTP), an electrophysiological surrogate of learning and memory, but normal Aβ levels. Acute reduction of TNF-α activity with a neutralizing anti-TNF-α antibody occludes the boost in amplitude of glutamatergic transmission and LTP suppression observed in young Trem2R47H/R47H rats. Thus, the microglia-specific pathogenic Trem2 variant boosts glutamatergic neuronal transmission and suppresses LTP by increasing brain TNF-α concentrations, directly linking microglia to neuronal dysfunction. Future studies will determine whether this phenomenon represents an early, Aβ-independent pathway that facilitates dementia pathogenesis in humans.
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Affiliation(s)
- Siqiang Ren
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Newark, United States.,Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
| | - Wen Yao
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Newark, United States.,Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
| | - Marc D Tambini
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Newark, United States.,Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
| | - Tao Yin
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Newark, United States.,Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
| | - Kelly A Norris
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Newark, United States.,Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Newark, United States.,Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
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Tambini MD, D'Adamio L. Trem2 Splicing and Expression are Preserved in a Human Aβ-producing, Rat Knock-in Model of Trem2-R47H Alzheimer's Risk Variant. Sci Rep 2020; 10:4122. [PMID: 32139718 PMCID: PMC7058057 DOI: 10.1038/s41598-020-60800-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/13/2020] [Indexed: 11/18/2022] Open
Abstract
The R47H variant of the Triggering-Receptor-Expressed on Myeloid cells 2 (TREM2) increases the risk of Alzheimer's disease (AD). Mutagenesis of exon 2 in Knock-in (KI) mouse models of the R47H variant introduced a cryptic splice site, leading to nonsense mediated decay. Since haploinsufficiency does not model Trem2-R47H function, a new rat KI model, the Trem2R47H KI rat was created. Human Aβ has higher propensity to form toxic Aβ species, which are considered the main pathogenic entity in AD, as compared to rodent Aβ, the rat Amyloid Precursor Protein (App) gene was mutated to produce human Aβ. Trem2 splicing and expression was measured in Trem2R47H KI rat brains and microglia by qualitative and quantitative RT-PCR. Trem2 levels and Trem2 processing was assessed by Western analysis. APP metabolite levels were determined by enzyme-linked immunosorbent assay (ELISA), for Human Aβ and soluble APP, and Western analysis, for full length APP, βCTF and αCTF. Trem2 expression and Trem2 levels are unchanged in Trem2R47H KI rats. The artifactual splicing seen in KI mouse models is not present; additionally, two novel isoforms of rat Trem2 are described. Trem2R47H rat brains have lower human Aβ38, sAPPα and sAPPβ levels. Thus, Trem2R47H KI rats may prove valuable to define pathogenic mechanisms triggered by the Trem2 R47H variant, including those mediated by toxic species of human Aβ peptides.
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Affiliation(s)
- Marc D Tambini
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA.
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Tambini MD, Norris KA, D'Adamio L. Opposite changes in APP processing and human Aβ levels in rats carrying either a protective or a pathogenic APP mutation. eLife 2020; 9:52612. [PMID: 32022689 PMCID: PMC7018507 DOI: 10.7554/elife.52612] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/03/2020] [Indexed: 12/13/2022] Open
Abstract
Cleavage of APP by BACE1/β-secretase initiates the amyloidogenic cascade leading to Amyloid-β (Aβ) production. α-Secretase initiates the non-amyloidogenic pathway preventing Aβ production. Several APP mutations cause familial Alzheimer's disease (AD), while the Icelandic APP mutation near the BACE1-cleavage site protects from sporadic dementia, emphasizing APP's role in dementia pathogenesis. To study APP protective/pathogenic mechanisms, we generated knock-in rats carrying either the protective (Appp) or the pathogenic Swedish mutation (Apps), also located near the BACE1-cleavage site. α-Cleavage is favored over β-processing in Appp rats. Consequently, non-amyloidogenic and amyloidogenic APP metabolites are increased and decreased, respectively. The reverse APP processing shift occurs in Apps rats. These opposite effects on APP β/α-processing suggest that protection from and pathogenesis of dementia depend upon combinatorial and opposite alterations in APP metabolism rather than simply on Aβ levels. The Icelandic mutation also protects from aging-dependent cognitive decline, suggesting that similar mechanisms underlie physiological cognitive aging.
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Affiliation(s)
- Marc D Tambini
- Department of Pharmacology Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
| | - Kelly A Norris
- Department of Pharmacology Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
| | - Luciano D'Adamio
- Department of Pharmacology Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, Newark, United States
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15
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Tambini MD, Yao W, D'Adamio L. Facilitation of glutamate, but not GABA, release in Familial Alzheimer's APP mutant Knock-in rats with increased β-cleavage of APP. Aging Cell 2019; 18:e13033. [PMID: 31496118 PMCID: PMC6826143 DOI: 10.1111/acel.13033] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 08/11/2019] [Indexed: 12/01/2022] Open
Abstract
Amyloid precursor protein (APP) modulates glutamate release via cytoplasmic and intravesicular interactions with the synaptic vesicle release machinery. The intravesicular domain, called ISVAID, contains the BACE1 cleavage site of APP. We have tested the functional significance of BACE1 processing of APP using App‐Swedish (Apps) knock‐in rats, which carry an App mutation that causes familial Alzheimer's disease (FAD) in humans. We show that in Apps rats, β‐cleavage of APP is favored over α‐cleavage. Apps rats show facilitated glutamate, but not GABA, release. Our data support the notion that APP tunes glutamate release, and that BACE1 cleavage of the ISVAID segment of APP facilitates this function. We define this phenomenon as BACE1 on APP‐dependent glutamate release (BAD‐Glu). Unsurprisingly, Apps rats show no evidence of AD‐related pathology at 15 days and 3 months of age, indicating that alterations in BAD‐Glu are not caused by pathological lesions. The evidence that a pathogenic APP mutation causes an early enhancement of BAD‐Glu suggests that alterations of BACE1 processing of APP in glutamatergic synaptic vesicles could contribute to dementia.
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Affiliation(s)
- Marc D. Tambini
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School Brain Health Institute Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research Rutgers, The State University of New Jersey Newark NJ USA
| | - Wen Yao
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School Brain Health Institute Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research Rutgers, The State University of New Jersey Newark NJ USA
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School Brain Health Institute Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research Rutgers, The State University of New Jersey Newark NJ USA
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Tuning of Glutamate, But Not GABA, Release by an Intrasynaptic Vesicle APP Domain Whose Function Can Be Modulated by β- or α-Secretase Cleavage. J Neurosci 2019; 39:6992-7005. [PMID: 31235642 DOI: 10.1523/jneurosci.0207-19.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 05/17/2019] [Accepted: 05/21/2019] [Indexed: 11/21/2022] Open
Abstract
APP, whose mutations cause familial Alzheimer's disease (FAD), modulates neurotransmission via interaction of its cytoplasmic tail with the synaptic release machinery. Here we identified an intravesicular domain of APP, called intraluminal SV-APP interacting domain (ISVAID), which interacts with glutamatergic, but not GABAergic, synaptic vesicle proteins. ISVAID contains the β- and α-secretase cleavage sites of APP: proteomic analysis of the interactome of ISVAID suggests that β- and α-secretase cleavage of APP cuts inside the interaction domain of ISVAID and destabilizes protein-protein interactions. We have tested the functional significance of the ISVAID and of β-/α-secretase-processing of APP using various ISVAID-derived peptides in competition experiments on both female and male mouse and rats hippocampal slices. A peptide encompassing the entire ISVAID facilitated glutamate, but not GABA, release acting as dominant negative inhibitor of the functions of this APP domain in acute hippocampal slices. In contrast, peptides representing the product of β-/α-secretase-processing of ISVAID did not alter excitatory neurotransmitter release. These findings suggest that cleavage of APP by either β- or α-secretase may inactivate the ISVAID, thereby enhancing glutamate release. Our present data support the notion that APP tunes glutamate release, likely through intravesicular and extravesicular interactions with synaptic vesicle proteins and the neurotransmitter release machinery, and that β-/α cleavage of APP facilitates the release of excitatory neurotransmitter.SIGNIFICANCE STATEMENT Alzheimer's disease has been linked to mutations in APP. However, the biological function of APP is poorly understood. Here we show that an intravesicular APP domain interacts with the proteins that control the release of glutamate, but not GABA. Interfering with the function of this domain promotes glutamate release. This APP domain contains the sites cleaved by β- and α-secretases: our data suggest that β-/α cleavage of APP inactivates this functional APP domain promoting excitatory neurotransmitter release.
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Yao W, Yin T, Tambini MD, D'Adamio L. The Familial dementia gene ITM2b/BRI2 facilitates glutamate transmission via both presynaptic and postsynaptic mechanisms. Sci Rep 2019; 9:4862. [PMID: 30890756 PMCID: PMC6425013 DOI: 10.1038/s41598-019-41340-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/07/2019] [Indexed: 12/12/2022] Open
Abstract
Mutations in the Integral membrane protein 2B (ITM2b/BRI2) gene, which codes for a protein called BRI2, cause familial British and Danish dementia (FBD and FDD). Loss of BRI2 function and/or accumulation of amyloidogenic mutant BRI2-derived peptides have been proposed to mediate FDD and FBD pathogenesis by impairing synaptic Long-term potentiation (LTP). However, the precise site and nature of the synaptic dysfunction remain unknown. Here we use a genetic approach to inactivate Itm2b in either presynaptic (CA3), postsynaptic (CA1) or both (CA3 + CA1) neurons of the hippocampal Schaeffer-collateral pathway in both female and male mice. We show that after CA3 + CA1 Itm2b inactivation, spontaneous glutamate release and AMPAR-mediated responses are decreased, while short-term synaptic facilitation is increased. Moreover, AMPAR-mediated responses are decreased after postsynaptic but not presynaptic deletion of Itm2b. In contrast, the probability of spontaneous glutamate release is decreased, while short-term synaptic facilitation is increased, primarily after presynaptic deletion of Itm2b. Collectively, these results indicate a dual physiological role of Itm2b in the regulation of excitatory synaptic transmission at both presynaptic termini and postsynaptic termini and suggest that presynaptic and postsynaptic dysfunctions may be a pathogenic event leading to dementia and neurodegeneration in FDD and FBD.
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Affiliation(s)
- Wen Yao
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Tao Yin
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Marc D Tambini
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA.
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18
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Targeting MicroRNA-143 Leads to Inhibition of Glioblastoma Tumor Progression. Cancers (Basel) 2018; 10:cancers10100382. [PMID: 30322013 PMCID: PMC6210372 DOI: 10.3390/cancers10100382] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/03/2018] [Accepted: 10/08/2018] [Indexed: 12/11/2022] Open
Abstract
Glioblastoma (GBM) is the most common and aggressive of all brain tumors, with a median survival of only 14 months after initial diagnosis. Novel therapeutic approaches are an unmet need for GBM treatment. MicroRNAs (miRNAs) are a class of small non-coding RNAs that regulate gene expression at the post-transcriptional level. Several dysregulated miRNAs have been identified in all cancer types including GBM. In this study, we aimed to uncover the role of miR-143 in GBM cell lines, patient samples, and mouse models. Quantitative real-time RT-PCR of RNA extracted from formalin-fixed paraffin-embedded (FFPE) samples showed that the relative expression of miR-143 was higher in GBM patients compared to control individuals. Transient transfection of GBM cells with a miR-143 oligonucleotide inhibitor (miR-143-inh) resulted in reduced cell proliferation, increased apoptosis, and cell cycle arrest. SLC30A8, a glucose metabolism-related protein, was identified as a direct target of miR-143 in GBM cells. Moreover, multiple injections of GBM tumor-bearing mice with a miR-143-inh-liposomal formulation significantly reduced tumor growth compared to control mice. The reduced in vitro cell growth and in vivo tumor growth following miRNA-143 inhibition suggests that miR-143 is a potential therapeutic target for GBM therapy.
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Martins F, Marafona AM, Pereira CD, Müller T, Loosse C, Kolbe K, da Cruz E Silva OAB, Rebelo S. Identification and characterization of the BRI2 interactome in the brain. Sci Rep 2018; 8:3548. [PMID: 29476059 PMCID: PMC5824958 DOI: 10.1038/s41598-018-21453-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 01/05/2018] [Indexed: 01/16/2023] Open
Abstract
BRI family proteins are ubiquitous type II transmembrane proteins but BRI2 is highly expressed in some neuronal tissues. Possible BRI2 functions include neuronal maturation and differentiation. Protein complexes appear to be important in mediating its functions. Previously described BRI2 interactors include the Alzheimer's amyloid precursor protein and protein phosphatase 1, but clearly the identification of novel interactors provides an important tool to understand the role and function of BRI2. To this end three rat brain regions (cerebellum, hippocampus, and cerebral cortex) were processed by BRI2 immunoprecipitation; co-precipitating proteins were identified by Nano-HPLC-MS/MS. The pool of the brain regions resulted in 511 BRI2 interacting proteins (BRI2 brain interactome) of which 120 were brain specific and 49 involved in neuronal differentiation. Brain region-specific analyses were also carried out for cerebellum, hippocampus, and cerebral cortex. Several novel BRI2 interactors were identified among them DLG4/PSD-95, which is singularly important as it places BRI2 in the postsynaptic compartment. This interaction was validated as well as the interaction with GAP-43 and synaptophysin. In essence, the resulting BRI2 brain interactome, associates this protein with neurite outgrowth and neuronal differentiation, as well as synaptic signalling and plasticity. It follows that further studies should address BRI2 particularly given its relevance to neuropathological conditions.
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Affiliation(s)
- Filipa Martins
- Neuroscience and Signalling Laboratory, Department of Medical Sciences, Institute of Biomedicine-iBiMED, University of Aveiro, Aveiro, Portugal
| | - Ana M Marafona
- Neuroscience and Signalling Laboratory, Department of Medical Sciences, Institute of Biomedicine-iBiMED, University of Aveiro, Aveiro, Portugal
| | - Cátia D Pereira
- Neuroscience and Signalling Laboratory, Department of Medical Sciences, Institute of Biomedicine-iBiMED, University of Aveiro, Aveiro, Portugal
| | - Thorsten Müller
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e. V., Dortmund, Germany
- Cell Signaling, Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
- Institute of Psychiatric Phenomics and Genomics, Clinical Center of the University of Munich, Nussbaumstr. 7, 80336, Munich, Germany
| | - Christina Loosse
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e. V., Dortmund, Germany
| | - Katharina Kolbe
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e. V., Dortmund, Germany
- Cell Signaling, Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
- Institute of Psychiatric Phenomics and Genomics, Clinical Center of the University of Munich, Nussbaumstr. 7, 80336, Munich, Germany
| | - Odete A B da Cruz E Silva
- Neuroscience and Signalling Laboratory, Department of Medical Sciences, Institute of Biomedicine-iBiMED, University of Aveiro, Aveiro, Portugal
| | - Sandra Rebelo
- Neuroscience and Signalling Laboratory, Department of Medical Sciences, Institute of Biomedicine-iBiMED, University of Aveiro, Aveiro, Portugal.
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Biundo F, Del Prete D, Zhang H, Arancio O, D'Adamio L. A role for tau in learning, memory and synaptic plasticity. Sci Rep 2018; 8:3184. [PMID: 29453339 PMCID: PMC5816660 DOI: 10.1038/s41598-018-21596-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 02/05/2018] [Indexed: 02/02/2023] Open
Abstract
Tau plays a pivotal role in the pathogenesis of neurodegenerative disorders: mutations in the gene encoding for tau (MAPT) are linked to Fronto-temporal Dementia (FTD) and hyper-phosphorylated aggregates of tau forming neurofibrillary tangles (NFTs) that constitute a pathological hallmark of Alzheimer disease (AD) and FTD. Accordingly, tau is a favored therapeutic target for the treatment of these diseases. Given the criticality of tau to dementia's pathogenesis and therapy, it is important to understand the physiological function of tau in the central nervous system. Analysis of Mapt knock out (Mapt-/-) mice has yielded inconsistent results. Some studies have shown that tau deletion does not alter memory while others have described synaptic plasticity and memory alterations in Mapt-/- mice. To help clarifying these contrasting results, we analyzed a distinct Mapt-/- model on a B6129PF3/J genetic background. We found that tau deletion leads to aging-dependent short-term memory deficits, hyperactivity and synaptic plasticity defects. In contrast, Mapt+/- mice only showed a mild short memory deficit in the novel object recognition task. Thus, while tau is important for normal neuronal functions underlying learning and memory, partial reduction of tau expression may have fractional deleterious effects.
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Affiliation(s)
- Fabrizio Biundo
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Dolores Del Prete
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Hong Zhang
- Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, 630 168 St., New York, NY, 10032, USA
| | - Ottavio Arancio
- Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, 630 168 St., New York, NY, 10032, USA
| | - Luciano D'Adamio
- Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA.
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Expression Pattern of the BCL6 and ITM2B Proteins in Normal Human Brains and in Alzheimer Disease. Appl Immunohistochem Mol Morphol 2018; 25:489-496. [PMID: 26862951 DOI: 10.1097/pai.0000000000000329] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We reported that the integral membrane 2B gene (ITM2B, also called BRI2) is a target of BCL6 repression in lymphomas. Molecular alterations in ITM2B are associated with 2 neurodegenerative diseases, Familial British and Danish dementia, and dysregulation of ITM2B function has been implicated in the pathogenesis of Alzheimer disease (AD). Although ITM2B expression has been studied, the distribution of BCL6 in human brain has not been described. Our goal is to analyze BCL6 and ITM2B localization in normal human brains and in AD by immunohistochemistry to understand their relationship. We found that, in general, they have a reciprocal relationship. BCL6 expression is present in isolated cortical neurons, granule cells in the cerebellum, scattered glial cells, and in some cells of the ependyma and choroid plexus. ITM2B is expressed in most cortical neurons, neurons of the hippocampus and dentate nucleus, cerebellar Purkinje and granule cells, and (newly described here) in focal neurons in the basal ganglia, many neurons of the thalamus and brainstem, many cells in the ependyma and choroid plexus, and in the smooth muscle of blood vessels. ITM2B expression is prominent in plaques in AD-containing dystrophic neurites but absent in neurofibrillary tangles; BCL6 expression is absent in neurofibrillary tangles and in the nuclei of cells associated with plaques in AD. It is essential to understand the localization of BCL6 and ITM2B in the brain before considering manipulation of their expression as a potential therapeutic tool.
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Deletion of the γ-secretase subunits Aph1B/C impairs memory and worsens the deficits of knock-in mice modeling the Alzheimer-like familial Danish dementia. Oncotarget 2017; 7:11923-44. [PMID: 26942869 PMCID: PMC4914259 DOI: 10.18632/oncotarget.7389] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 02/08/2016] [Indexed: 12/26/2022] Open
Abstract
Mutations in BRI2/ITM2b genes cause Familial British and Danish Dementias (FBD and FDD), which are pathogenically similar to Familial Alzheimer Disease (FAD). BRI2 inhibits processing of Amyloid precursor protein (APP), a protein involved in FAD pathogenesis. Accumulation of a carboxyl-terminal APP metabolite -ß-CTF- causes memory deficits in a knock-in mouse model of FDD, called FDDKI.We have investigated further the pathogenic function of ß-CTF studying the effect of Aph1B/C deletion on FDDKI mice. This strategy is based on the evidence that deletion of Aph1B/C proteins, which are components of the γ-secretase that cleaves ß-CTF, results in stabilization of ß-CTF and a reduction of Aβ. We found that both the FDD mutation and the Aph1B/C deficiency mildly interfered with spatial long term memory, spatial working/short-term memory and long-term contextual fear memory. In addition, the Aph1BC deficiency induced deficits in long-term cued fear memory. Moreover, the two mutations have additive adverse effects as they compromise the accuracy of spatial long-term memory and induce spatial memory retention deficits in young mice. Overall, the data are consistent with a role for β-CTF in the genesis of memory deficits.
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Abolishing Tau cleavage by caspases at Aspartate 421 causes memory/synaptic plasticity deficits and pre-pathological Tau alterations. Transl Psychiatry 2017; 7:e1198. [PMID: 28786980 PMCID: PMC5611732 DOI: 10.1038/tp.2017.165] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 05/30/2017] [Accepted: 06/07/2017] [Indexed: 01/03/2023] Open
Abstract
TAU mutations are genetically linked to fronto-temporal dementia (FTD) and hyper-phosphorylated aggregates of Tau form neurofibrillary tangles (NFTs) that constitute a pathological hallmark of Alzheimer disease (AD) and FTD. These observations indicate that Tau has a pivotal role in the pathogenesis of neurodegenerative disorders. Tau is cleaved by caspases at Aspartate421, to form a Tau metabolite known as δTau; δTau is increased in AD, due to the hyper-activation of caspases in AD brains. δTau is considered a critical toxic moiety underlying neurodegeneration, which initiates and facilitates NFT formation. As Tau is a therapeutic target in neurodegeneration, it is important to rigorously determine whether δTau is a toxic Tau species that should be pharmacologically attacked. To directly address these questions, we have generated a knock-in (KI) mouse called TauDN-that expresses a Tau mutant that cannot be cleaved by caspases. TauDN mice present short-term memory deficits and synaptic plasticity defects. Moreover, mice carrying two mutant Tau alleles show increased total insoluble hyper-phosphorylated Tau in the forebrain. These data are in contrast with the concept that δTau is a critical toxic moiety underlying neurodegeneration, and suggest that cleavage of Tau by caspases represents a negative feedback mechanism aimed to eliminate toxic Tau species. Alternatively, it is possible that either a reduction or an increase in δTau leads to synaptic dysfunction, memory impairments and Tau pathology. Both possibilities will have to be considered when targeting caspase cleavage of Tau in AD therapy.
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Buxbaum JN, Johansson J. Transthyretin and BRICHOS: The Paradox of Amyloidogenic Proteins with Anti-Amyloidogenic Activity for Aβ in the Central Nervous System. Front Neurosci 2017; 11:119. [PMID: 28360830 PMCID: PMC5350149 DOI: 10.3389/fnins.2017.00119] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 02/27/2017] [Indexed: 01/19/2023] Open
Abstract
Amyloid fibrils are physiologically insoluble biophysically specific β-sheet rich structures formed by the aggregation of misfolded proteins. In vivo tissue amyloid formation is responsible for more than 30 different disease states in humans and other mammals. One of these, Alzheimer's disease (AD), is the most common form of human dementia for which there is currently no definitive treatment. Amyloid fibril formation by the amyloid β-peptide (Aβ) is considered to be an underlying cause of AD, and strategies designed to reduce Aβ production and/or its toxic effects are being extensively investigated in both laboratory and clinical settings. Transthyretin (TTR) and proteins containing a BRICHOS domain are etiologically associated with specific amyloid diseases in the CNS and other organs. Nonetheless, it has been observed that TTR and BRICHOS structures are efficient inhibitors of Aβ fibril formation and toxicity in vitro and in vivo, raising the possibility that some amyloidogenic proteins, or their precursors, possess properties that may be harnessed for combating AD and other amyloidoses. Herein, we review properties of TTR and the BRICHOS domain and discuss how their abilities to interfere with amyloid formation may be employed in the development of novel treatments for AD.
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Affiliation(s)
- Joel N Buxbaum
- Department of Molecular and Experimental Medicine, The Scripps Research InstituteLa Jolla, CA, USA; Scintillon InstituteSan Diego, CA, USA
| | - Jan Johansson
- Division of Neurogeriatrics, Department of Neurobiology, Care Sciences, and Society (NVS), Center for Alzheimer Research, Karolinska Institutet Huddinge, Sweden
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Garringer HJ, Sammeta N, Oblak A, Ghetti B, Vidal R. Amyloid and intracellular accumulation of BRI 2. Neurobiol Aging 2016; 52:90-97. [PMID: 28131015 DOI: 10.1016/j.neurobiolaging.2016.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/29/2016] [Accepted: 12/18/2016] [Indexed: 01/07/2023]
Abstract
Familial British dementia (FBD) and familial Danish dementia (FDD) are caused by mutations in the BRI2 gene. These diseases are characterized clinically by progressive dementia and ataxia and neuropathologically by amyloid deposits and neurofibrillary tangles. Herein, we investigate BRI2 protein accumulation in FBD, FDD, Alzheimer disease and Gerstmann-Sträussler-Scheinker disease. In FBD and FDD, we observed reduced processing of the mutant BRI2 pro-protein, which was found accumulating intracellularly in the Golgi of neurons and glial cells. In addition, we observed an accumulation of a mature form of BRI2 protein in dystrophic neurites, surrounding amyloid cores. Accumulation of BRI2 was also observed in dystrophic neurites of Alzheimer disease and Gerstmann-Sträussler-Scheinker disease cases. Although it remains to be determined whether intracellular accumulation of BRI2 may lead to cell damage in these degenerative diseases, our study provides new insights into the role of mutant BRI2 in the pathogenesis of FBD and FDD and implicates BRI2 as a potential indicator of neuritic damage in diseases characterized by cerebral amyloid deposition.
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Affiliation(s)
- Holly J Garringer
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Neeraja Sammeta
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Adrian Oblak
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Bernardino Ghetti
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ruben Vidal
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, IN, USA.
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Biundo F, Ishiwari K, Del Prete D, D'Adamio L. Interaction of ApoE3 and ApoE4 isoforms with an ITM2b/BRI2 mutation linked to the Alzheimer disease-like Danish dementia: Effects on learning and memory. Neurobiol Learn Mem 2015; 126:18-30. [PMID: 26528887 DOI: 10.1016/j.nlm.2015.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 10/09/2015] [Accepted: 10/15/2015] [Indexed: 12/30/2022]
Abstract
Mutations in Amyloid β Precursor Protein (APP) and in genes that regulate APP processing--such as PSEN1/2 and ITM2b/BRI2--cause familial dementia, such Familial Alzheimer disease (FAD), Familial Danish (FDD) and British (FBD) dementias. The ApoE gene is the major genetic risk factor for sporadic AD. Three major variants of ApoE exist in humans (ApoE2, ApoE3, and ApoE4), with the ApoE4 allele being strongly associated with AD. ITM2b/BRI2 is also a candidate regulatory node genes predicted to mediate the common patterns of gene expression shared by healthy ApoE4 carriers and late-onset AD patients not carrying ApoE4. This evidence provides a direct link between ITM2b/BRI2 and ApoE4. To test whether ApoE4 and pathogenic ITM2b/BRI2 interact to modulate learning and memory, we crossed a mouse carrying the ITM2b/BRI2 mutations that causes FDD knocked-in the endogenous mouse Itm2b/Bri2 gene (FDDKI mice) with human ApoE3 and ApoE4 targeted replacement mice. The resultant ApoE3, FDDKI/ApoE3, ApoE4, FDDKI/ApoE4 male mice were assessed longitudinally for learning and memory at 4, 6, 12, and 16-17 months of age. The results showed that ApoE4-carrying mice displayed spatial working/short-term memory deficits relative to ApoE3-carrying mice starting in early middle age, while long-term spatial memory of ApoE4 mice was not adversely affected even at 16-17 months, and that the FDD mutation impaired working/short-term spatial memory in ApoE3-carrying mice and produced impaired long-term spatial memory in ApoE4-carrying mice in middle age. The present results suggest that the FDD mutation may differentially affect learning and memory in ApoE4 carriers and non-carriers.
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Affiliation(s)
- Fabrizio Biundo
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States
| | - Keita Ishiwari
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States
| | - Dolores Del Prete
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States
| | - Luciano D'Adamio
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States.
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27
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Abstract
Here we review the similarities between a rare inherited disorder, familial British dementia (FBD), and the most common of all late-life neurological conditions, Alzheimer's diseases (AD). We describe the symptoms, pathology and genetics of FBD, the biology of the BRI2 protein and mouse models of FBD and familial Danish dementia. In particular, we focus on the evolving recognition of the importance of protein oligomers and aberrant processing of the amyloid β-protein precursor (APP) - themes that are common to both FBD and AD. The initial discovery that FBD is phenotypically similar to AD, but associated with the deposition of an amyloid peptide (ABri) distinct from the amyloid β-protein (Aβ) led many to assume that amyloid production alone is sufficient to initiate disease and that ABri is the molecular equivalent of Aβ. Parallel with work on Aβ, studies of ABri producing animal models and in vitro ABri toxicity experiments caused a revision of the amyloid hypothesis and a focus on soluble oligomers of Aβ and ABri. Contemporaneous other studies suggested that loss of the ABri precursor protein (BRI2) may underlie the cognitive deficits in FBD. In this regard it is important to note that BRI2 has been shown to interact with and regulate the processing of APP, and that mutant BRI2 leads to altered cleavage of APP. A synthesis of these results suggests that a “two-hit mechanism” better explains FBD than earlier toxic gain of function and toxic loss of function models. The lessons learned from the study of FBD imply that the molecular pathology of AD is also likely to involve both aberrant aggregation (in AD, Aβ) and altered APP processing. With regard to FBD, we propose that the C-terminal 11 amino acid of FBD-BRI2 interfere with both the normal function of BRI2 and promotes the production of cystine cross-linked toxic ABri oligomers. In this scenario, loss of BRI2 function leads to altered APP processing in as yet underappreciated ways. Given the similarities between FBD and AD it seems likely that study of the structure of ABri oligomers and FBD-induced changes in APP metabolites will further our understanding of AD.
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Affiliation(s)
- Adam Cantlon
- Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Republic of Ireland ; Laboratory for Neurodegenerative Research, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Carlo Sala Frigerio
- Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Republic of Ireland
| | - Dominic M Walsh
- Laboratory for Neurodegenerative Research, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
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Cantlon A, Frigerio CS, Freir DB, Boland B, Jin M, Walsh DM. The Familial British Dementia Mutation Promotes Formation of Neurotoxic Cystine Cross-linked Amyloid Bri (ABri) Oligomers. J Biol Chem 2015; 290:16502-16. [PMID: 25957407 DOI: 10.1074/jbc.m115.652263] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Indexed: 01/29/2023] Open
Abstract
Familial British dementia (FBD) is an inherited neurodegenerative disease believed to result from a mutation in the BRI2 gene. Post-translational processing of wild type BRI2 and FBD-BRI2 result in the production of a 23-residue long Bri peptide and a 34-amino acid long ABri peptide, respectively, and ABri is found deposited in the brains of individuals with FBD. Similarities in the neuropathology and clinical presentation shared by FBD and Alzheimer disease (AD) have led some to suggest that ABri and the AD-associated amyloid β-protein (Aβ) are molecular equivalents that trigger analogous pathogenic cascades. But the sequences and innate properties of ABri and Aβ are quite different, notably ABri contains two cysteine residues that can form disulfide bonds. Thus we sought to determine whether ABri was neurotoxic and if this activity was regulated by oxidation and/or aggregation. Crucially, the type of oxidative cross-linking dramatically influenced both ABri aggregation and toxicity. Cyclization of Bri and ABri resulted in production of biologically inert monomers that showed no propensity to assemble, whereas reduced ABri and reduced Bri aggregated forming thioflavin T-positive amyloid fibrils that lacked significant toxic activity. ABri was more prone to form inter-molecular disulfide bonds than Bri and the formation of covalently stabilized ABri oligomers was associated with toxicity. These results suggest that extension of the C-terminal of Bri causes a shift in the type of disulfide bonds formed and that structures built from covalently cross-linked oligomers can interact with neurons and compromise their function and viability.
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Affiliation(s)
- Adam Cantlon
- From the Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Republic of Ireland and the Laboratory for Neurodegenerative Research, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
| | - Carlo Sala Frigerio
- From the Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Republic of Ireland and
| | - Darragh B Freir
- From the Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Republic of Ireland and
| | - Barry Boland
- From the Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Republic of Ireland and
| | - Ming Jin
- the Laboratory for Neurodegenerative Research, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
| | - Dominic M Walsh
- the Laboratory for Neurodegenerative Research, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
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29
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Del Campo M, Oliveira CR, Scheper W, Zwart R, Korth C, Müller-Schiffmann A, Kostallas G, Biverstal H, Presto J, Johansson J, Hoozemans JJ, Pereira CF, Teunissen CE. BRI2 ectodomain affects Aβ42 fibrillation and tau truncation in human neuroblastoma cells. Cell Mol Life Sci 2015; 72:1599-611. [PMID: 25336154 PMCID: PMC11113771 DOI: 10.1007/s00018-014-1769-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 10/15/2014] [Accepted: 10/17/2014] [Indexed: 11/29/2022]
Abstract
Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded proteins such as amyloid beta (Aβ) in senile plaques, and hyperphosphorylated tau and truncated tau in neurofibrillary tangles (NFT). The BRI2 protein inhibits Aβ aggregation via its BRICHOS domain and regulates critical proteins involved in initiating the amyloid cascade, which has been hypothesized to be central in AD pathogenesis. We recently detected the deposition of BRI2 ectodomain associated with Aβ plaques and concomitant changes in its processing enzymes in early stages of AD. Here, we aimed to investigate the effects of recombinant BRI2 ectodomain (rBRI276-266) on Aβ aggregation and on important molecular pathways involved in early stages of AD, including the unfolded protein response (UPR), phosphorylation and truncation of tau, as well as apoptosis. We found that rBRI276-266 delays Aβ fibril formation, although less efficiently than the BRI2 BRICHOS domain (BRI2 residues 113-231). In human neuroblastoma SH-SY5Y cells, rBRI276-266 slightly decreased cell viability and increased up to two-fold the Bax/Bcl-2 ratio and the subsequent activity of caspases 3 and 9, indicating activation of apoptosis. rBRI276-266 upregulated the chaperone BiP but did not modify the mRNA expression of other UPR markers (CHOP and Xbp-1). Strikingly, rBRI276-266 induced the activation of GSK3β but not the phosphorylation of tau. However, exposure to rBRI276-266 significantly induced the truncation of tau, indicating that BRI2 ectodomain can contribute to NFT formation. Since BRI2 can also regulate the metabolism of Aβ, the current data suggests that BRI2 ectodomain is a potential nexus between Aβ, tau pathology and neurodegeneration.
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Affiliation(s)
- M Del Campo
- Neurochemistry Laboratory, Department of Clinical Chemistry, VU University Medical Center (VUmc), Room PK1 Br016, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands,
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30
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Del Campo M, Stargardt A, Veerhuis R, Reits E, Teunissen CE. Accumulation of BRI2-BRICHOS ectodomain correlates with a decreased clearance of Aβ by insulin degrading enzyme (IDE) in Alzheimer's disease. Neurosci Lett 2015; 589:47-51. [PMID: 25597881 DOI: 10.1016/j.neulet.2015.01.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 01/13/2015] [Accepted: 01/14/2015] [Indexed: 01/22/2023]
Abstract
The precursor protein BRI2 that in its mutated form is associated with British and Danish dementia, can regulate critical processes involved in AD pathogenesis including not only the metabolism of amyloid precursor protein (APP) and formation of Aβ, but also the levels of secreted insulin degrading enzyme (IDE), an enzyme involved in Aβ clearance. We recently observed increased levels of a 45kDa BRI2 form as well as BRI2 ectodomain deposits in Aβ plaques in human AD hippocampus, which may affect BRI2 functional activity. Since BRI2 regulated the levels of secreted IDE and subsequent degradation of Aβ in human cell culture models, we explored if BRI2 changes could affect the Aβ degradation capacity of IDE in human hippocampus (n=28). We observed that IDE is the main enzyme involved in Aβ degradation, and both IDE levels as well as Aβ degradation tend to be decreased in AD. Interestingly, the levels of the 45kDa BRI2 form and BRI2 deposits in hippocampal tissue were inversely correlated with IDE protein levels (r=-0.52, p=0.005; r=-0.4, p=0.045) and IDE activity (r=-0.5935, p=0.0004; r=-0.4, p=0.03). Taken together, the current results suggest a relationship between BRI2 protein changes, IDE activity and Aβ levels in human hippocampus. Thus, the formation and accumulation high of molecular weight BRI2 forms observed in AD may impair IDE functioning and consequently lead to impaired Aβ clearance and to the accumulation of Aβ.
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Affiliation(s)
- M Del Campo
- Neurochemistry Laboratory of the Clinical Chemistry department, VU University Medical Center, 1081HV, Amsterdam, The Netherlands; Alzheimer Center, VU University Medical Center, 1081HV, Amsterdam, The Netherlands.
| | - A Stargardt
- Department of Cell Biology and Histology, Academic Medical Center, Amsterdam, The Netherlands
| | - R Veerhuis
- Neurochemistry Laboratory of the Clinical Chemistry department, VU University Medical Center, 1081HV, Amsterdam, The Netherlands; Psychiatry department, VU University Medical Center, 1081HV, Amsterdam, The Netherlands
| | - E Reits
- Department of Cell Biology and Histology, Academic Medical Center, Amsterdam, The Netherlands
| | - C E Teunissen
- Neurochemistry Laboratory of the Clinical Chemistry department, VU University Medical Center, 1081HV, Amsterdam, The Netherlands
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The ITM2B (BRI2) gene is a target of BCL6 repression: Implications for lymphomas and neurodegenerative diseases. Biochim Biophys Acta Mol Basis Dis 2014; 1852:742-8. [PMID: 25557390 DOI: 10.1016/j.bbadis.2014.12.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 12/21/2014] [Accepted: 12/25/2014] [Indexed: 11/20/2022]
Abstract
The human BCL6 gene encodes a transcriptional repressor that is crucial for germinal center B cell development and T follicular helper cell differentiation. It is involved in the pathogenesis of certain human lymphomas. In an effort to identify targets of BCL6 repression, we used a previously described cell system in which BCL6 repressive effects are inhibited, followed by subtractive hybridization, and identified the integral membrane 2B gene (ITM2B, formerly BRI2) as a potential target. Here we show that BCL6 can bind to its preferential consensus binding site within the first intron of ITM2B and represses its transcription. Knockdown of endogenous BCL6 in a human B cell lymphoma line increases ITM2B expression. Further, there is an inverse relationship between the expression levels of BCL6 and ITM2B proteins in 16 human B- and T-cell lymphomas studied by immunohistochemistry. Both the BCL6 and ITM2B proteins are expressed ubiquitously. Similar to some other targets of BCL6, a short form of the ITM2B protein generated by alternative splicing induces apoptosis in hematopoietic cell lines. Molecular alterations in the ITM2B gene are associated with two neurodegenerative diseases, Familial British and Familial Danish dementia. ITM2B dysfunction also may be relevant for the development of Alzheimer's disease. Our data confirm ITM2B as a target of BCL6 repression in lymphoma. A further understanding of the genes that function as regulators of the ITM2B protein may provide insights for the development of new molecular tools not only for targeted lymphoma therapy but also for the treatment of these dementias.
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Gispert S, Brehm N, Weil J, Seidel K, Rüb U, Kern B, Walter M, Roeper J, Auburger G. Potentiation of neurotoxicity in double-mutant mice with Pink1 ablation and A53T-SNCA overexpression. Hum Mol Genet 2014; 24:1061-76. [PMID: 25296918 PMCID: PMC4986551 DOI: 10.1093/hmg/ddu520] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The common age-related neurodegeneration of Parkinson's disease can result from dominant causes like increased dosage of vesicle-associated alpha-synuclein (SNCA) or recessive causes like deficiency of mitophagy factor PINK1. Interactions between these triggers and their convergence onto shared pathways are crucial, but currently conflicting evidence exists. Here, we crossed previously characterized mice with A53T-SNCA overexpression and with Pink1 deletion to generate double mutants (DMs). We studied their lifespan and behavior, histological and molecular anomalies at late and early ages. DM animals showed potentiated phenotypes in comparison with both single mutants (SMs), with reduced survival and strongly reduced spontaneous movements from the age of 3 months onwards. In contrast to SMs, a quarter of DM animals manifested progressive paralysis at ages >1 year and exhibited protein aggregates immunopositive for pSer129-SNCA, p62 and ubiquitin in spinal cord and basal brain. Brain proteome quantifications of ubiquitination sites documented altered degradation of SNCA and the DNA-damage marker H2AX at the age of 18 months. Global brain transcriptome profiles and qPCR validation experiments identified many consistent transcriptional dysregulations already at the age of 6 weeks, which were absent from SMs. The observed downregulations for Dapk1, Dcaf17, Rab42 and the novel SNCA-marker Lect1 as well as the upregulations for Dctn5, Mrpl9, Tmem181a, Xaf1 and H2afx reflect changes in ubiquitination, mitochondrial/synaptic/microtubular/cell adhesion dynamics and DNA damage. Thus, our study confirmed that SNCA-triggered neurotoxicity is exacerbated by the absence of PINK1 and identified a novel molecular signature that is detectable early in the course of this double pathology.
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Affiliation(s)
- Suzana Gispert
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Nadine Brehm
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Jonas Weil
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Kay Seidel
- Dr. Senckenbergisches Chronomedizinisches Institut, Goethe-University Medical School, 60590 Frankfurt/Main, Germany
| | - Udo Rüb
- Dr. Senckenbergisches Chronomedizinisches Institut, Goethe-University Medical School, 60590 Frankfurt/Main, Germany
| | - Beatrice Kern
- Institute of Neurophysiology, Neuroscience Center, Goethe University Frankfurt, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany and
| | - Michael Walter
- Institute for Medical Genetics, Eberhard-Karls-University of Tuebingen, 72076 Tübingen, Germany
| | - Jochen Roeper
- Institute of Neurophysiology, Neuroscience Center, Goethe University Frankfurt, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany and
| | - Georg Auburger
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany,
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Meyer MA. Highly Expressed Genes within Hippocampal Sector CA1: Implications for the Physiology of Memory. Neurol Int 2014; 6:5388. [PMID: 24987507 PMCID: PMC4077213 DOI: 10.4081/ni.2014.5388] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 04/07/2014] [Indexed: 11/23/2022] Open
Abstract
As the CA1 sector has been implicated to play a key role in memory formation, a dedicated search for highly expressed genes within this region was made from an on-line atlas of gene expression within the mouse brain (GENSAT). From a data base of 1013 genes, 16 were identified that had selective localization of gene expression within the CA1 region, and included Angpt2, ARHGEF6, CCK, Cntnap1, DRD3, EMP1, Epha2, Itm2b, Lrrtm2, Mdk, PNMT, Ppm1e, Ppp2r2d, RASGRP1, Slitrk5, and Sstr4. Of the 16 identified, the most selective and intense localization for both adult and post-natal day 7 was noted for ARHGEF6, which is known to be linked to non-syndromic mental retardation, and has also been localized to dendritic spines. Further research on the role played by ARHGEF6 in memory formation is strongly advocated
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Affiliation(s)
- Michael A Meyer
- Department of Neurology, Sisters Hospital , Buffalo, NY, USA
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34
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Del Campo M, Hoozemans JJM, Dekkers LL, Rozemuller AJ, Korth C, Müller-Schiffmann A, Scheltens P, Blankenstein MA, Jimenez CR, Veerhuis R, Teunissen CE. BRI2-BRICHOS is increased in human amyloid plaques in early stages of Alzheimer's disease. Neurobiol Aging 2014; 35:1596-604. [PMID: 24524963 DOI: 10.1016/j.neurobiolaging.2014.01.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 12/31/2013] [Accepted: 01/08/2014] [Indexed: 10/25/2022]
Abstract
BRI2 protein binds amyloid precursor protein to halt amyloid-β production and inhibits amyloid-β aggregation via its BRICHOS-domain suggesting a link between BRI2 and Alzheimer's disease (AD). Here, we investigate the possible involvement of BRI2 in human AD pathogenesis. BRI2 containing BRICHOS-domain was increased up to 3-fold in AD hippocampus (p = 0.003, n = 14/group). Immunohistochemistry showed BRI2 deposits associated with amyloid-β plaques in early pathologic stages (Braak-III; Thal-2/3). We observed a decrease in the protein levels of ADAM10 (p = 0.02) and furin (p = 0.066), as well as an increase in SPPL2b (p < 0.0001) in AD hippocampus. Because these enzymes are involved in BRI2 processing, their changes may lead to aberrant processing of BRI2 promoting its deposition and likely affecting BRI2 function. Loss of BRI2 function in AD was supported by the decreased presence of BRI2-amyloid precursor protein complexes in the hippocampus of AD patients compared with control subjects. In conclusion, our data obtained from human samples indicate that in early stages of AD there is an increased deposition of BRI2, which likely leads to impaired BRI2 function thereby influencing AD pathophysiology.
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Affiliation(s)
- Marta Del Campo
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, the Netherlands; Neurochemistry Laboratory, VU University Medical Center, Amsterdam, the Netherlands; Alzheimer Center, VU University Medical Center, Amsterdam, the Netherlands.
| | - Jeroen J M Hoozemans
- Department of Pathology, VU University Medical Center, Amsterdam, the Netherlands
| | - Lois-Lee Dekkers
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, the Netherlands; Neurochemistry Laboratory, VU University Medical Center, Amsterdam, the Netherlands
| | | | - Carsten Korth
- Department of Neuropathology, Heinrich Heine University Medical School, Düsseldorf, Germany
| | | | - Philip Scheltens
- Alzheimer Center, VU University Medical Center, Amsterdam, the Netherlands
| | - Marinus A Blankenstein
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, the Netherlands; Neurochemistry Laboratory, VU University Medical Center, Amsterdam, the Netherlands
| | - Connie R Jimenez
- Department of Medical Oncology and OncoProteomics Laboratory, VU University Medical Center, Amsterdam, the Netherlands
| | - Robert Veerhuis
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, the Netherlands; Neurochemistry Laboratory, VU University Medical Center, Amsterdam, the Netherlands; Department of Pathology, VU University Medical Center, Amsterdam, the Netherlands; Department of Psychiatry, VU University Medical Center, Amsterdam, the Netherlands
| | - Charlotte E Teunissen
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, the Netherlands; Neurochemistry Laboratory, VU University Medical Center, Amsterdam, the Netherlands
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35
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Marcora MS, Fernández-Gamba AC, Avendaño LA, Rotondaro C, Podhajcer OL, Vidal R, Morelli L, Ceriani MF, Castaño EM. Amyloid peptides ABri and ADan show differential neurotoxicity in transgenic Drosophila models of familial British and Danish dementia. Mol Neurodegener 2014; 9:5. [PMID: 24405716 PMCID: PMC3898387 DOI: 10.1186/1750-1326-9-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 12/29/2013] [Indexed: 11/16/2022] Open
Abstract
Background Familial British and Familial Danish dementias (FBD and FDD, respectively) are associated with mutations in the BRI2 gene. Processing of the mutated BRI2 protein leads to the accumulation in the brain of the 34-mer amyloid Bri (ABri) and amyloid Dan (ADan) peptides, accompanied by neurofibrillary tangles. Recently, transgenic mice successfully reproduced different aspects of FDD, while modeling of FBD in vivo has been more difficult. In this work we have modeled FBD and FDD in Drosophila and tested the hypothesis that ABri and ADan are differentially neurotoxic. Results By using site-directed insertion, we generated transgenic lines carrying ABri, ADan, Bri2-23 (the normal product of wild-type BRI2 processing) and amyloid-β (Aβ) 1–42 as a well-characterized neurotoxic peptide, alone or with a His-tag. Therefore, we avoided random insertion effects and were able to compare levels of accumulation accurately. Peptides were expressed with the GAL4-Upstream Activating Sequence (UAS) system using specific drivers. Despite low levels of expression, toxicity in the eye was characterized by mild disorganization of ommatidia and amyloid peptides accumulation. The highest toxicity was seen for ADan, followed by Aβ42 and ABri. Pan-neuronal expression in the CNS revealed an age-dependent toxicity of amyloid peptides as determined by the ability of flies to climb in a geotaxis paradigm when compared to Bri2-23. This effect was stronger for ADan, detected at 7 days post-eclosion, and followed by ABri and Aβ42, whose toxicity became evident after 15 and 21 days, respectively. Histological analysis showed mild vacuolization and thioflavine-S-negative deposits of amyloid peptides. In contrast, the over-expression of amyloid peptides in the specific subset of lateral neurons that control circadian locomotor activity showed no toxicity. Conclusions Our results support the differential neurotoxicity of ADan and ABri in the Drosophila eye and CNS at low expression levels. Such differences may be partially attributed to rates of aggregation and accumulation. In the CNS, both peptides appear to be more neurotoxic than wild-type Aβ42. These Drosophila models will allow a systematic and unambiguous comparison of differences and similarities in the mechanisms of toxicity of diverse amyloid peptides associated with dementia.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Eduardo M Castaño
- From Fundación Instituto Leloir, Av, Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina.
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Knight SD, Presto J, Linse S, Johansson J. The BRICHOS Domain, Amyloid Fibril Formation, and Their Relationship. Biochemistry 2013; 52:7523-31. [DOI: 10.1021/bi400908x] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Stefan D. Knight
- Department
of Cell and Molecular Biology, Uppsala University, 751 05 Uppsala, Sweden
| | - Jenny Presto
- KI-Alzheimer’s Disease Research
Center, NVS Department, Karolinska Institutet, S-141 86 Stockholm, Sweden
| | - Sara Linse
- Department
of Biochemistry and Structural Biology, Lund University, Chemical Centre, P.O.
Box 124, SE221 00 Lund, Sweden
| | - Jan Johansson
- KI-Alzheimer’s Disease Research
Center, NVS Department, Karolinska Institutet, S-141 86 Stockholm, Sweden
- Department
of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, 751 23 Uppsala, Sweden
- Institute
of Mathematics and Natural Sciences, Tallinn University, Narva mnt
25, 101 20 Tallinn, Estonia
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Garringer HJ, Murrell J, Sammeta N, Gnezda A, Ghetti B, Vidal R. Increased tau phosphorylation and tau truncation, and decreased synaptophysin levels in mutant BRI2/tau transgenic mice. PLoS One 2013; 8:e56426. [PMID: 23418567 PMCID: PMC3572042 DOI: 10.1371/journal.pone.0056426] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 01/10/2013] [Indexed: 01/24/2023] Open
Abstract
Familial Danish dementia (FDD) is an autosomal dominant neurodegenerative disease caused by a 10-nucleotide duplication-insertion in the BRI2 gene. FDD is clinically characterized by loss of vision, hearing impairment, cerebellar ataxia and dementia. The main neuropathologic findings in FDD are the deposition of Danish amyloid (ADan) and the presence of neurofibrillary tangles (NFTs). Here we investigated tau accumulation and truncation in double transgenic (Tg-FDD-Tau) mice generated by crossing transgenic mice expressing human Danish mutant BRI2 (Tg-FDD) with mice expressing human 4-repeat mutant Tau-P301S (Tg-Tau). Compared to Tg-Tau mice, we observed a significant enhancement of tau deposition in Tg-FDD-Tau mice. In addition, a significant increase in tau cleaved at aspartic acid (Asp) 421 was observed in Tg-FDD-Tau mice. Tg-FDD-Tau mice also showed a significant decrease in synaptophysin levels, occurring before widespread deposition of fibrillar ADan and tau can be observed. Thus, the presence of soluble ADan/mutant BRI2 can lead to significant changes in tau metabolism and synaptic dysfunction. Our data provide new in vivo insights into the pathogenesis of FDD and the pathogenic pathway(s) by which amyloidogenic peptides, regardless of their primary amino acid sequence, can cause neurodegeneration.
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Affiliation(s)
- Holly J. Garringer
- Department of Pathology and Laboratory Medicine and Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- * E-mail: (RV); (HJG)
| | - Jill Murrell
- Department of Pathology and Laboratory Medicine and Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Neeraja Sammeta
- Department of Pathology and Laboratory Medicine and Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Anita Gnezda
- Department of Pathology and Laboratory Medicine and Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Bernardino Ghetti
- Department of Pathology and Laboratory Medicine and Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Ruben Vidal
- Department of Pathology and Laboratory Medicine and Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- * E-mail: (RV); (HJG)
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Matsuda S, Tamayev R, D'Adamio L. Increased AβPP processing in familial Danish dementia patients. J Alzheimers Dis 2012; 27:385-91. [PMID: 21841249 DOI: 10.3233/jad-2011-110785] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
An autosomal dominant mutation in the BRI2/ITM2B gene causes Familial Danish Dementia (FDD). We have generated a mouse model of FDD, called FDDKI, genetically congruous to the human disease. These mice carry one mutant and one wild type Bri2/Itm2b allele, like FDD patients. Analysis of FDDKI mice and samples from human patients has shown that the Danish mutation causes loss of Bri2 protein. FDDKI mice show synaptic plasticity and memory impairments. BRI2 is a physiological interactor of amyloid-β protein precursor (AβPP), a gene associated with Alzheimer's disease, which inhibits processing of AβPP. AβPP/Bri2 complexes are reduced in synaptic membranes of FDDKI mice. Consequently, AβPP metabolites derived from processing of AβPP by β-, α-, and γ-secretases are increased in Danish dementia mice. AβPP haplodeficiency prevents memory and synaptic dysfunctions, consistent with a role for AβPP-metabolites in the pathogenesis of memory and synaptic deficits. This genetic suppression provides compelling evidence that AβPP and BRI2 functionally interact. Here, we have investigated whether AβPP processing is altered in FDD patients' brain samples. We find that the levels of several AβPP metabolites, including Aβ, are significantly increased in the brain sample derived from an FDD patient. Our data are consistent with the findings in FDDKI mice, and support the hypothesis that the neurological effects of the Danish form of BRI2 are caused by toxic AβPP metabolites, suggesting that Familial Danish and Alzheimer's dementias share common pathogenic mechanisms.
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Affiliation(s)
- Shuji Matsuda
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
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Memory deficits of British dementia knock-in mice are prevented by Aβ-precursor protein haploinsufficiency. J Neurosci 2012; 32:5481-5. [PMID: 22514310 DOI: 10.1523/jneurosci.5193-11.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Familial British Dementia (FBD) is caused by an autosomal dominant mutation in the BRI2/ITM2B gene (Vidal et al., 1999). FBD(KI) mice are a model of FBD that is genetically congruous to the human disease, because they carry one mutant and one wild-type Bri2/Itm2b allele. Analysis of these mice has shown that the British mutation causes memory impairments due to loss of Bri2 function (Tamayev et al., 2010b). BRI2 is a physiologic inhibitor of processing of the Aβ-precursor protein (APP; Matsuda et al., 2008), a gene associated with Alzheimer's disease (Bertram et al., 2010). Here we show that APP haploinsufficiency prevents memory dysfunctions seen in FBD(KI) mice. This genetic suppression is consistent with a role for APP in the pathogenesis of memory deficits. Moreover, it provides compelling evidence that the memory dysfunctions caused by the British BRI2 mutant are dependent on endogenous APP and that BRI2 and APP functionally interact. This evidence establishes a mechanistic connection between Familial British and Alzheimer's dementias.
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Tamayev R, D'Adamio L. Inhibition of γ-secretase worsens memory deficits in a genetically congruous mouse model of Danish dementia. Mol Neurodegener 2012; 7:19. [PMID: 22537414 PMCID: PMC3407505 DOI: 10.1186/1750-1326-7-19] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 04/26/2012] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND A mutation in the BRI2/ITM2b gene causes familial Danish dementia (FDD). BRI2 is an inhibitor of amyloid-β precursor protein (APP) processing, which is genetically linked to Alzheimer's disease (AD) pathogenesis. The FDD mutation leads to a loss of BRI2 protein and to increased APP processing. APP haplodeficiency and inhibition of APP cleavage by β-secretase rescue synaptic/memory deficits of a genetically congruous mouse model of FDD (FDDKI). β-cleavage of APP yields the β-carboxyl-terminal (β-CTF) and the amino-terminal-soluble APPβ (sAPPβ) fragments. γ-secretase processing of β-CTF generates Aβ, which is considered the main cause of AD. However, inhibiting Aβ production did not rescue the deficits of FDDKI mice, suggesting that sAPPβ/β-CTF, and not Aβ, are the toxic species causing memory loss. RESULTS Here, we have further analyzed the effect of γ-secretase inhibition. We show that treatment with a γ-secretase inhibitor (GSI) results in a worsening of the memory deficits of FDDKI mice. This deleterious effect on memory correlates with increased levels of the β/α-CTFs APP fragments in synaptic fractions isolated from hippocampi of FDDKI mice, which is consistent with inhibition of γ-secretase activity. CONCLUSION This harmful effect of the GSI is in sharp contrast with a pathogenic role for Aβ, and suggests that the worsening of memory deficits may be due to accumulation of synaptic-toxic β/α-CTFs caused by GSI treatment. However, γ-secretase cleaves more than 40 proteins; thus, the noxious effect of GSI on memory may be dependent on inhibition of cleavage of one or more of these other γ-secretase substrates. These two possibilities do not need to be mutually exclusive. Our results are consistent with the outcome of a clinical trial with the GSI Semagacestat, which caused a worsening of cognition, and advise against targeting γ-secretase in the therapy of AD. Overall, the data also indicate that FDDKI is a valuable mouse model to study AD pathogenesis and predict the clinical outcome of therapeutic agents for AD.
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Affiliation(s)
- Robert Tamayev
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Proteomic characterization of a mouse model of familial Danish dementia. J Biomed Biotechnol 2012; 2012:728178. [PMID: 22619496 PMCID: PMC3350990 DOI: 10.1155/2012/728178] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Accepted: 02/02/2012] [Indexed: 11/18/2022] Open
Abstract
A dominant mutation in the ITM2B/BRI2 gene causes familial Danish dementia (FDD) in humans. To model FDD in animal systems, a knock-in approach was recently implemented in mice expressing a wild-type and mutant allele, which bears the FDD-associated mutation. Since these FDD(KI) mice show behavioural alterations and impaired synaptic function, we characterized their synaptosomal proteome via two-dimensional differential in-gel electrophoresis. After identification by nanoliquid chromatography coupled to electrospray-linear ion trap tandem mass spectrometry, the differentially expressed proteins were classified according to their gene ontology descriptions and their predicted functional interactions. The Dlg4/Psd95 scaffold protein and additional signalling proteins, including protein phosphatases, were revealed by STRING analysis as potential players in the altered synaptic function of FDD(KI) mice. Immunoblotting analysis finally demonstrated the actual downregulation of the synaptosomal scaffold protein Dlg4/Psd95 and of the dual-specificity phosphatase Dusp3 in the synaptosomes of FDD(KI) mice.
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Tamayev R, Matsuda S, Arancio O, D'Adamio L. β- but not γ-secretase proteolysis of APP causes synaptic and memory deficits in a mouse model of dementia. EMBO Mol Med 2012; 4:171-9. [PMID: 22170863 PMCID: PMC3376850 DOI: 10.1002/emmm.201100195] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 11/30/2011] [Accepted: 12/05/2011] [Indexed: 02/04/2023] Open
Abstract
A mutation in the BRI2/ITM2b gene causes loss of BRI2 protein leading to familial Danish dementia (FDD). BRI2 deficiency of FDD provokes an increase in amyloid-β precursor protein (APP) processing since BRI2 is an inhibitor of APP proteolysis, and APP mediates the synaptic/memory deficits in FDD. APP processing is linked to Alzheimer disease (AD) pathogenesis, which is consistent with a common mechanism involving toxic APP metabolites in both dementias. We show that inhibition of APP cleavage by β-secretase rescues synaptic/memory deficits in a mouse model of FDD. β-cleavage of APP yields amino-terminal-soluble APPβ (sAPPβ) and β-carboxyl-terminal fragments (β-CTF). Processing of β-CTF by γ-secretase releases amyloid-β (Aβ), which is assumed to cause AD. However, inhibition of γ-secretase did not ameliorate synaptic/memory deficits of FDD mice. These results suggest that sAPPβ and/or β-CTF, rather than Aβ, are the toxic species causing dementia, and indicate that reducing β-cleavage of APP is an appropriate therapeutic approach to treating human dementias. Our data and the failures of anti-Aβ therapies in humans advise against targeting γ-secretase cleavage of APP and/or Aβ.
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Affiliation(s)
- Robert Tamayev
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
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Kilger E, Buehler A, Woelfing H, Kumar S, Kaeser SA, Nagarathinam A, Walter J, Jucker M, Coomaraswamy J. BRI2 protein regulates β-amyloid degradation by increasing levels of secreted insulin-degrading enzyme (IDE). J Biol Chem 2011; 286:37446-57. [PMID: 21873424 DOI: 10.1074/jbc.m111.288373] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The amyloid precursor protein (APP) is one of the major proteins involved in Alzheimer disease (AD). Proteolytic cleavage of APP gives rise to amyloid-β (Aβ) peptides that aggregate and deposit extensively in the brain of AD patients. Although the increase in levels of aberrantly folded Aβ peptide is considered to be important to disease pathogenesis, the regulation of APP processing and Aβ metabolism is not fully understood. Recently, the British precursor protein (BRI2, ITM2B) has been implicated in influencing APP processing in cells and Aβ deposition in vivo. Here, we show that the wild type BRI2 protein reduces plaque load in an AD mouse model, similar to its disease-associated mutant form, ADan precursor protein (ADanPP), and analyze in more detail the mechanism of how BRI2 and ADanPP influence APP processing and Aβ metabolism. We find that overexpression of either BRI2 or ADanPP reduces extracellular Aβ by increasing levels of secreted insulin-degrading enzyme (IDE), a major Aβ-degrading protease. This effect is also observed with BRI2 lacking its C-terminal 23-amino acid peptide sequence. Our results suggest that BRI2 might act as a receptor protein that regulates IDE levels that in turn influences APP metabolism in a previously unrecognized way. Targeting the regulation of IDE may be a promising therapeutic approach to sporadic AD.
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Affiliation(s)
- Ellen Kilger
- Department of Cellular Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, D-72076 Tübingen, Germany.
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BRICHOS domain associated with lung fibrosis, dementia and cancer - a chaperone that prevents amyloid fibril formation? FEBS J 2011; 278:3893-904. [DOI: 10.1111/j.1742-4658.2011.08209.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Tamayev R, Matsuda S, Giliberto L, Arancio O, D'Adamio L. APP heterozygosity averts memory deficit in knockin mice expressing the Danish dementia BRI2 mutant. EMBO J 2011; 30:2501-9. [PMID: 21587206 DOI: 10.1038/emboj.2011.161] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 04/27/2011] [Indexed: 11/09/2022] Open
Abstract
An autosomal dominant mutation in the BRI2/ITM2B gene causes familial Danish dementia (FDD). Analysis of FDD(KI) mice, a mouse model of FDD genetically congruous to the human disease since they carry one mutant and one wild-type Bri2/Itm2b allele, has shown that the Danish mutation causes loss of Bri2 protein, synaptic plasticity and memory impairments. BRI2 is a physiological interactor of Aβ-precursor protein (APP), a gene associated with Alzheimer disease, which inhibits processing of APP. Here, we show that APP/Bri2 complexes are reduced in synaptic membranes of FDD(KI) mice. Consequently, APP metabolites derived from processing of APP by β-, α- and γ-secretases are increased in Danish dementia mice. APP haplodeficiency prevents memory and synaptic dysfunctions, consistent with a role for APP metabolites in the pathogenesis of memory and synaptic deficits. This genetic suppression provides compelling evidence that APP and BRI2 functionally interact, and that the neurological effects of the Danish form of BRI2 only occur when sufficient levels of APP are supplied by two alleles. This evidence establishes a pathogenic sameness between familial Danish and Alzheimer's dementias.
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Affiliation(s)
- Robert Tamayev
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
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Danish dementia mice suggest that loss of function and not the amyloid cascade causes synaptic plasticity and memory deficits. Proc Natl Acad Sci U S A 2010; 107:20822-7. [PMID: 21098268 DOI: 10.1073/pnas.1011689107] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
According to the prevailing "amyloid cascade hypothesis," genetic dementias such as Alzheimer's disease and familial Danish dementia (FDD) are caused by amyloid deposits that trigger tauopathy, neurodegeneration, and behavioral/cognitive alterations. To efficiently reproduce amyloid lesions, murine models of human dementias invariably use transgenic expression systems. However, recent FDD transgenic models showed that Danish amyloidosis does not cause memory defects, suggesting that other mechanisms cause Danish dementia. We studied an animal knock-in model of FDD (FDD(KI/+)) genetically congruous with human cases. FDD(KI/+) mice present reduced Bri2 levels, impaired synaptic plasticity and severe hippocampal memory deficits. These animals show no cerebral lesions that are reputed characteristics of human dementia, such as tangles or amyloid plaques. Bri2(+/-) mice exhibit synaptic and memory deficits similar to FDD(KI/+) mice, and memory loss of FDD(KI/+) mice is prevented by expression of WT BRI2, indicating that Danish dementia is caused by loss of BRI2 function. Together, the data suggest that clinical dementia in Danish patients occurs via a loss of function mechanism and not as a result of amyloidosis and tauopathy.
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