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Takano-Kawabe K, Matoba K, Nakamura Y, Moriyama M. Low Density Lipoprotein Receptor-related Protein 2 Expression and Function in Cultured Astrocytes and Microglia. Neurochem Res 2024; 49:199-211. [PMID: 37702891 DOI: 10.1007/s11064-023-04022-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 09/14/2023]
Abstract
Activation of glial cells, astrocytes and microglia, has been observed in neurodegenerative diseases including Alzheimer's disease (AD). Amyloid β (Aβ), which is aggregated and the aggregation is detected as characteristic pathology in AD brain, is known to be produced by neurons and to activate glial cells. Clearance of Aβ from the brain via active transport system is important to prevent the accumulation and aggregation. Low density lipoprotein receptor-related protein 2 (LRP2/megalin) is an Aβ transporter. However, expression and contribution of LRP2 in astrocytes and microglia remain to be clarified. In the present study, we examined the expression of LRP2 and its roles in cultured astrocytes prepared from rat embryonic brain cortex and mouse microglial cell line BV-2. Both cultured rat astrocytes and BV-2 cells expressed LRP2 mRNA detected by RT-PCR. When lipopolysaccharide (LPS) or all-trans retinoic acid (ATRA) were added to BV-2 cells, LRP2 mRNA expression and uptake of microbeads, Aβ and insulin were increased. On the other hand, LPS decreased LRP2 expression and uptake of Aβ and insulin in cultured astrocytes. Knockdown of LRP2 using siRNA attenuated the LPS- or ATRA-increased uptake of microbeads, Aβ and insulin in BV-2 cells. These results suggest that LRP2 was expressed in both astrocytes and microglia and might be involved in endocytosis activities. Adequate control of LRP2 expression and function in astrocytes and microglia might regulate Aβ and insulin levels in brain and would be a potential target in AD pathology.
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Affiliation(s)
- Katsura Takano-Kawabe
- Laboratory of Integrative Physiology in Veterinary Sciences, Osaka Metropolitan University, 1-58, Rinku-Ourai Kita, Izumisano, Osaka, 598-8531, Japan.
| | - Kazuyuki Matoba
- Laboratory of Integrative Physiology in Veterinary Sciences, Osaka Metropolitan University, 1-58, Rinku-Ourai Kita, Izumisano, Osaka, 598-8531, Japan
| | - Yoichi Nakamura
- Laboratory of Integrative Physiology in Veterinary Sciences, Osaka Metropolitan University, 1-58, Rinku-Ourai Kita, Izumisano, Osaka, 598-8531, Japan
| | - Mitsuaki Moriyama
- Laboratory of Integrative Physiology in Veterinary Sciences, Osaka Metropolitan University, 1-58, Rinku-Ourai Kita, Izumisano, Osaka, 598-8531, Japan
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2
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Reid KM, Brown GC. LRPAP1 is released from activated microglia and inhibits microglial phagocytosis and amyloid beta aggregation. Front Immunol 2023; 14:1286474. [PMID: 38035103 PMCID: PMC10687467 DOI: 10.3389/fimmu.2023.1286474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/30/2023] [Indexed: 12/02/2023] Open
Abstract
Low-density lipoprotein receptor-related protein-associated protein 1 (LRPAP1), also known as receptor associated protein (RAP), is an endoplasmic reticulum (ER) chaperone and inhibitor of LDL receptor related protein 1 (LRP1) and related receptors. These receptors have dozens of physiological ligands and cell functions, but it is not known whether cells release LRPAP1 physiologically at levels that regulate these receptors and cell functions. We used mouse BV-2 and human CHME3 microglial cell lines, and found that microglia released nanomolar levels of LRPAP1 when inflammatory activated by lipopolysaccharide or when ER stressed by tunicamycin. LRPAP1 was found on the surface of live activated and non-activated microglia, and anti-LRPAP1 antibodies induced internalization. Addition of 10 nM LRPAP1 inhibited microglial phagocytosis of isolated synapses and cells, and the uptake of Aβ. LRPAP1 also inhibited Aβ aggregation in vitro. Thus, activated and stressed microglia release LRPAP1 levels that can inhibit phagocytosis, Aβ uptake and Aβ aggregation. We conclude that LRPAP1 release may regulate microglial functions and Aβ pathology, and more generally that extracellular LRPAP1 may be a physiological and pathological regulator of a wide range of cell functions.
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Affiliation(s)
| | - Guy C. Brown
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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3
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Hampel H, Hardy J, Blennow K, Chen C, Perry G, Kim SH, Villemagne VL, Aisen P, Vendruscolo M, Iwatsubo T, Masters CL, Cho M, Lannfelt L, Cummings JL, Vergallo A. The Amyloid-β Pathway in Alzheimer's Disease. Mol Psychiatry 2021; 26:5481-5503. [PMID: 34456336 PMCID: PMC8758495 DOI: 10.1038/s41380-021-01249-0] [Citation(s) in RCA: 578] [Impact Index Per Article: 192.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 07/19/2021] [Accepted: 07/28/2021] [Indexed: 02/06/2023]
Abstract
Breakthroughs in molecular medicine have positioned the amyloid-β (Aβ) pathway at the center of Alzheimer's disease (AD) pathophysiology. While the detailed molecular mechanisms of the pathway and the spatial-temporal dynamics leading to synaptic failure, neurodegeneration, and clinical onset are still under intense investigation, the established biochemical alterations of the Aβ cycle remain the core biological hallmark of AD and are promising targets for the development of disease-modifying therapies. Here, we systematically review and update the vast state-of-the-art literature of Aβ science with evidence from basic research studies to human genetic and multi-modal biomarker investigations, which supports a crucial role of Aβ pathway dyshomeostasis in AD pathophysiological dynamics. We discuss the evidence highlighting a differentiated interaction of distinct Aβ species with other AD-related biological mechanisms, such as tau-mediated, neuroimmune and inflammatory changes, as well as a neurochemical imbalance. Through the lens of the latest development of multimodal in vivo biomarkers of AD, this cross-disciplinary review examines the compelling hypothesis- and data-driven rationale for Aβ-targeting therapeutic strategies in development for the early treatment of AD.
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Affiliation(s)
- Harald Hampel
- Eisai Inc., Neurology Business Group, Woodcliff Lake, NJ, USA.
| | - John Hardy
- UK Dementia Research Institute at UCL and Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, UK
| | - Kaj Blennow
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden
| | - Christopher Chen
- Memory Aging and Cognition Centre, Departments of Pharmacology and Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - George Perry
- Department of Biology and Neurosciences Institute, University of Texas at San Antonio (UTSA), San Antonio, TX, USA
| | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea; Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Victor L Villemagne
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
| | - Paul Aisen
- USC Alzheimer's Therapeutic Research Institute, San Diego, CA, USA
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Takeshi Iwatsubo
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Colin L Masters
- Laureate Professor of Dementia Research, Florey Institute and The University of Melbourne, Parkville, VIC, Australia
| | - Min Cho
- Eisai Inc., Neurology Business Group, Woodcliff Lake, NJ, USA
| | - Lars Lannfelt
- Uppsala University, Department of of Public Health/Geriatrics, Uppsala, Sweden
- BioArctic AB, Stockholm, Sweden
| | - Jeffrey L Cummings
- Chambers-Grundy Center for Transformative Neuroscience, Department of Brain Health, School of Integrated Health Sciences, University of Nevada Las Vegas (UNLV), Las Vegas, NV, USA
| | - Andrea Vergallo
- Eisai Inc., Neurology Business Group, Woodcliff Lake, NJ, USA.
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He Y, Ruganzu JB, Jin H, Peng X, Ji S, Ma Y, Zheng L, Yang W. LRP1 knockdown aggravates Aβ 1-42-stimulated microglial and astrocytic neuroinflammatory responses by modulating TLR4/NF-κB/MAPKs signaling pathways. Exp Cell Res 2020; 394:112166. [PMID: 32645395 DOI: 10.1016/j.yexcr.2020.112166] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/02/2020] [Accepted: 07/05/2020] [Indexed: 12/22/2022]
Abstract
Neuroinflammation is an important pathological feature and an early event in the pathogenesis of Alzheimer's disease (AD), which is characterized by activation of microglia and astrocytes. Low-density lipoprotein receptor-related protein 1 (LRP1) is an endocytic receptor that is abundantly expressed in neurons, microglia, and astrocytes, and plays a critical role in AD pathogenesis. There is increasing evidence to show that LRP1 regulates inflammatory responses by modulating the release of pro-inflammatory cytokines and phagocytosis. However, the effects of LRP1 on β-amyloid protein (Aβ)-induced microglial and astrocytic neuroinflammatory responses and its underlying mechanisms have not been studied in detail. In the present study, knockdown of LRP1 significantly enhanced Aβ1-42-stimulated neuroinflammation by increasing the production of pro-inflammatory cytokines in both BV2 microglial cells and mouse primary astrocytes. Furthermore, it is revealed that LRP1 knockdown further led to the activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) signaling pathways. The phosphorylation of IκBα, p38, and JNK was significantly up-regulated in LRP1 knockdown BV2 microglial cells and primary astrocytes. Meanwhile, LRP1 knockdown increased expression of the NF-κB p65 subunit in the nucleus while decreased its expression in the cytoplasm. Besides, the upstream signaling adaptor molecules such as toll-like receptor 4 (TLR4), myeloid differentiation primary response protein 88 (MyD88), and tumor necrosis factor receptor-associated factor 6 (TRAF6) were also further increased. Moreover, blockade of NF-κB, p38, and JNK inhibited the production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) induced by the knockdown of LRP1. Taken together, these findings indicated that LRP1 as an effective therapeutic target against AD and other neuroinflammation related diseases.
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Affiliation(s)
- Yingying He
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - John Bosco Ruganzu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Hui Jin
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Xiaoqian Peng
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Shengfeng Ji
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Yanbing Ma
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Liming Zheng
- Basic Medical Experimental Teaching Center, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Weina Yang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China.
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Zuroff L, Daley D, Black KL, Koronyo-Hamaoui M. Clearance of cerebral Aβ in Alzheimer's disease: reassessing the role of microglia and monocytes. Cell Mol Life Sci 2017; 74:2167-2201. [PMID: 28197669 PMCID: PMC5425508 DOI: 10.1007/s00018-017-2463-7] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/07/2017] [Accepted: 01/11/2017] [Indexed: 01/03/2023]
Abstract
Deficiency in cerebral amyloid β-protein (Aβ) clearance is implicated in the pathogenesis of the common late-onset forms of Alzheimer’s disease (AD). Accumulation of misfolded Aβ in the brain is believed to be a net result of imbalance between its production and removal. This in turn may trigger neuroinflammation, progressive synaptic loss, and ultimately cognitive decline. Clearance of cerebral Aβ is a complex process mediated by various systems and cell types, including vascular transport across the blood–brain barrier, glymphatic drainage, and engulfment and degradation by resident microglia and infiltrating innate immune cells. Recent studies have highlighted a new, unexpected role for peripheral monocytes and macrophages in restricting cerebral Aβ fibrils, and possibly soluble oligomers. In AD transgenic (ADtg) mice, monocyte ablation or inhibition of their migration into the brain exacerbated Aβ pathology, while blood enrichment with monocytes and their increased recruitment to plaque lesion sites greatly diminished Aβ burden. Profound neuroprotective effects in ADtg mice were further achieved through increased cerebral recruitment of myelomonocytes overexpressing Aβ-degrading enzymes. This review summarizes the literature on cellular and molecular mechanisms of cerebral Aβ clearance with an emphasis on the role of peripheral monocytes and macrophages in Aβ removal.
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Affiliation(s)
- Leah Zuroff
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA.,Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David Daley
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA
| | - Keith L Black
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA
| | - Maya Koronyo-Hamaoui
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA. .,Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, USA.
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6
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Wang Z, Xiong L, Wan W, Duan L, Bai X, Zu H. Intranasal BMP9 Ameliorates Alzheimer Disease-Like Pathology and Cognitive Deficits in APP/PS1 Transgenic Mice. Front Mol Neurosci 2017; 10:32. [PMID: 28228716 PMCID: PMC5296319 DOI: 10.3389/fnmol.2017.00032] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 01/27/2017] [Indexed: 01/01/2023] Open
Abstract
Alzheimer’s disease (AD) is the most common type of dementia and has no effective therapies. Previous studies showed that bone morphogenetic protein 9 (BMP9), an important factor in the differentiation and phenotype maintenance of cholinergic neurons, ameliorated the cholinergic defects resulting from amyloid deposition. These findings suggest that BMP9 has potential as a therapeutic agent for AD. However, the effects of BMP9 on cognitive function in AD and its underlying mechanisms remain elusive. In the present study, BMP9 was delivered intranasally to 7-month-old APP/PS1 mice for 4 weeks. Our data showed that intranasal BMP9 administration significantly improved the spatial and associative learning and memory of APP/PS1 mice. We also found that intranasal BMP9 administration significantly reduced the amyloid β (Aβ) plaques overall, inhibited tau hyperphosphorylation, and suppressed neuroinflammation in the transgenic mouse brain. Furthermore, intranasal BMP9 administration significantly promoted the expression of low-density lipoprotein receptor-related protein 1 (LRP1), an important membrane receptor involved in the clearance of amyloid β via the blood-brain barrier (BBB), and elevated the phosphorylation levels of glycogen synthase kinase-3β (Ser9), which is considered the main kinase involved in tau hyperphosphorylation. Our results suggest that BMP9 may be a promising candidate for treating AD by targeting multiple key pathways in the disease pathogenesis.
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Affiliation(s)
- Zigao Wang
- Department of Neurology, Jinshan Hospital, Fudan University Shanghai, China
| | - Lu Xiong
- Department of Anesthesiology, Tinglin Hospital Shanghai, China
| | - Wenbin Wan
- Department of Neurology, Zhongshan Hospital, Fudan University Shanghai, China
| | - Lijie Duan
- Department of Neurology, Jinshan Hospital, Fudan University Shanghai, China
| | - Xiaojing Bai
- Department of Neurology, Jinshan Hospital, Fudan University Shanghai, China
| | - Hengbing Zu
- Department of Neurology, Jinshan Hospital, Fudan University Shanghai, China
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7
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Yang L, Liu CC, Zheng H, Kanekiyo T, Atagi Y, Jia L, Wang D, N'songo A, Can D, Xu H, Chen XF, Bu G. LRP1 modulates the microglial immune response via regulation of JNK and NF-κB signaling pathways. J Neuroinflammation 2016; 13:304. [PMID: 27931217 PMCID: PMC5146875 DOI: 10.1186/s12974-016-0772-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/02/2016] [Indexed: 01/07/2023] Open
Abstract
Background Neuroinflammation is characterized by microglial activation and the increased levels of cytokines and chemokines in the central nervous system (CNS). Recent evidence has implicated both beneficial and toxic roles of microglia when over-activated upon nerve injury or in neurodegenerative diseases, including Alzheimer’s disease (AD). The low-density lipoprotein receptor-related protein 1 (LRP1) is a major receptor for apolipoprotein E (apoE) and amyloid-β (Aβ), which play critical roles in AD pathogenesis. LRP1 regulates inflammatory responses in peripheral tissues by modulating the release of inflammatory cytokines and phagocytosis. However, the roles of LRP1 in brain innate immunity and neuroinflammation remain unclear. Methods In this study, we determined whether LRP1 modulates microglial activation by knocking down Lrp1 in mouse primary microglia. LRP1-related functions in microglia were also assessed in the presence of LRP1 antagonist, the receptor-associated protein (RAP). The effects on the production of inflammatory cytokines were measured by quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). Potential involvement of specific signaling pathways in LRP1-regulated functions including mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB) were assessed using specific inhibitors. Results We found that knocking down of Lrp1 in mouse primary microglia led to the activation of both c-Jun N-terminal kinase (JNK) and NF-κB pathways with corresponding enhanced sensitivity to lipopolysaccharide (LPS) in the production of pro-inflammatory cytokines. Similar effects were observed when microglia were treated with LRP1 antagonist RAP. In addition, treatment with pro-inflammatory stimuli suppressed Lrp1 expression in microglia. Interestingly, NF-κB inhibitor not only suppressed the production of cytokines induced by the knockdown of Lrp1 but also restored the down-regulated expression of Lrp1 by LPS. Conclusions Our study uncovers that LRP1 suppresses microglial activation by modulating JNK and NF-κB signaling pathways. Given that dysregulation of LRP1 has been associated with AD pathogenesis, our work reveals a critical regulatory mechanism of microglial activation by LRP1 that could be associated with other AD-related pathways thus further nominating LRP1 as a potential disease-modifying target for the treatment of AD.
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Affiliation(s)
- Longyu Yang
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China
| | - Chia-Chen Liu
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL32224, USA
| | - Honghua Zheng
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China
| | - Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL32224, USA
| | - Yuka Atagi
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL32224, USA
| | - Lin Jia
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China
| | - Daxin Wang
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China
| | - Aurelie N'songo
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL32224, USA
| | - Dan Can
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China
| | - Huaxi Xu
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China
| | - Xiao-Fen Chen
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China. .,Shenzhen Research Institute of Xiamen University, Shenzhen, 518063, China.
| | - Guojun Bu
- Institute of Neuroscience, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Medical College, Xiamen University, Xiamen, 361102, China. .,Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL32224, USA.
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8
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Choucair N, Laporte V, Levy R, Tranchant C, Gies JP, Poindron P, Lombard Y. The Role of Calcium and Magnesium Ions in Uptake of β-Amyloid Peptides by Microglial Cells. Int J Immunopathol Pharmacol 2016; 19:683-96. [PMID: 17026853 DOI: 10.1177/039463200601900324] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Amyloid peptides 1-40 and 1-42 (Aβ 1-40 and Aβ 1-42) are major components of diffuse and neuritic senile plaques present in the brain of patients with Alzheimer's disease. Their interaction with microglial cells was studied using a system partly mimicking these plaques, which consisted in heat-killed yeast particles coated with either Aβ 1-40 or Aβ 1-42. Using these particles, it has been shown in our laboratory that LRP is involved mainly in the elimination of Aβ 1-42-coated heat-killed yeast particles and partly in that of Aβ 1-40-coated heat-killed yeast particles by microglial cells in culture. We show here that in the presence of calcium and magnesium ions extracellular chelators, namely EDTA (for both ions) and EGTA (for calcium ions), the internalization of coated heat-killed particles was impaired. In the presence of BAPTA-AM, an intracellular chelator of calcium ions and thapsigargin, an inhibitor of the endoplasmic reticulum calcium pump, no effect was observed on the phagocytosis of Aβ 1-40-coated heat-killed yeast particles, whereas that of Aβ 1-42-coated heat-killed yeast particles was affected. These results suggest that different signaling mechanisms are involved after the internalization of Aβ 1-40 and Aβ 1-42.
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Affiliation(s)
- N Choucair
- UMR 7175-LC1 Departement de Pharmacologie et Physicochimie des Interactions Cellulaires et Moleculaires, University Louis Pasteur, Illkirch Cedex, France
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9
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Ma KG, Lv J, Hu XD, Shi LL, Chang KW, Chen XL, Qian YH, Yang WN, Qu QM. The p38 mitogen-activated protein kinase signaling pathway is involved in regulating low-density lipoprotein receptor-related protein 1-mediated β-amyloid protein internalization in mouse brain. Int J Biochem Cell Biol 2016; 76:75-86. [PMID: 27163530 DOI: 10.1016/j.biocel.2016.04.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 04/22/2016] [Accepted: 04/28/2016] [Indexed: 01/15/2023]
Abstract
Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Recently, increasing evidence suggests that intracellular β-amyloid protein (Aβ) alone plays a pivotal role in the progression of AD. Therefore, understanding the signaling pathway and proteins that control Aβ internalization may provide new insight for regulating Aβ levels. In the present study, the regulation of Aβ internalization by p38 mitogen-activated protein kinases (MAPK) through low-density lipoprotein receptor-related protein 1 (LRP1) was analyzed in vivo. The data derived from this investigation revealed that Aβ1-42 were internalized by neurons and astrocytes in mouse brain, and were largely deposited in mitochondria and lysosomes, with some also being found in the endoplasmic reticulum. Aβ1-42-LRP1 complex was formed during Aβ1-42 internalization, and the p38 MAPK signaling pathway was activated by Aβ1-42 via LRP1. Aβ1-42 and LRP1 were co- localized in the cells of parietal cortex and hippocampus. Furthermore, the level of LRP1-mRNA and LRP1 protein involved in Aβ1-42 internalization in mouse brain. The results of this investigation demonstrated that Aβ1-42 induced an LRP1-dependent pathway that related to the activation of p38 MAPK resulting in internalization of Aβ1-42. These results provide evidence supporting a key role for the p38 MAPK signaling pathway which is involved in the regulation of Aβ1-42 internalization in the parietal cortex and hippocampus of mouse through LRP1 in vivo.
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Affiliation(s)
- Kai-Ge Ma
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China
| | - Jia Lv
- Department of Nephrology, First Affiliated Hospital of Xi'an Jiaotong University, 277 Yanta West Road, Xi'an, 710061, China
| | - Xiao-Dan Hu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China
| | - Li-Li Shi
- Department of Human Anatomy, Xi'an Medical University, 1 Xinwang road, Xi'an, 710021, China
| | - Ke-Wei Chang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China
| | - Xin-Lin Chen
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China; Institute of Neurobiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center,76 Yanta West Road, Xi'an, 710061, China
| | - Yi-Hua Qian
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China; Institute of Neurobiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center,76 Yanta West Road, Xi'an, 710061, China.
| | - Wei-Na Yang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China; Institute of Neurobiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center,76 Yanta West Road, Xi'an, 710061, China.
| | - Qiu-Min Qu
- Department of Neurology, First Affiliated Hospital of Xi'an Jiaotong University, 277 Yanta West Road, Xi'an, 710061, China.
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Kanekiyo T, Bu G. The low-density lipoprotein receptor-related protein 1 and amyloid-β clearance in Alzheimer's disease. Front Aging Neurosci 2014; 6:93. [PMID: 24904407 PMCID: PMC4033011 DOI: 10.3389/fnagi.2014.00093] [Citation(s) in RCA: 188] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/28/2014] [Indexed: 11/24/2022] Open
Abstract
Accumulation and aggregation of amyloid-β (Aβ) peptides in the brain trigger the development of progressive neurodegeneration and dementia associated with Alzheimer’s disease (AD). Perturbation in Aβ clearance, rather than Aβ production, is likely the cause of sporadic, late-onset AD, which accounts for the majority of AD cases. Since cellular uptake and subsequent degradation constitute a major Aβ clearance pathway, the receptor-mediated endocytosis of Aβ has been intensely investigated. Among Aβ receptors, the low-density lipoprotein receptor-related protein 1 (LRP1) is one of the most studied receptors. LRP1 is a large endocytic receptor for more than 40 ligands, including apolipoprotein E, α2-macroglobulin and Aβ. Emerging in vitro and in vivo evidence demonstrates that LRP1 is critically involved in brain Aβ clearance. LRP1 is highly expressed in a variety of cell types in the brain including neurons, vascular cells and glial cells, where LRP1 functions to maintain brain homeostasis and control Aβ metabolism. LRP1-mediated endocytosis regulates cellular Aβ uptake by binding to Aβ either directly or indirectly through its co-receptors or ligands. Furthermore, LRP1 regulates several signaling pathways, which also likely influences Aβ endocytic pathways. In this review, we discuss how LRP1 regulates the brain Aβ clearance and how this unique endocytic receptor participates in AD pathogenesis. Understanding of the mechanisms underlying LRP1-mediated Aβ clearance should enable the rational design of novel diagnostic and therapeutic strategies for AD.
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Affiliation(s)
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville FL, USA
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11
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Kanekiyo T, Xu H, Bu G. ApoE and Aβ in Alzheimer's disease: accidental encounters or partners? Neuron 2014; 81:740-54. [PMID: 24559670 DOI: 10.1016/j.neuron.2014.01.045] [Citation(s) in RCA: 423] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2014] [Indexed: 12/26/2022]
Abstract
Among the three human apolipoprotein E (apoE) isoforms, apoE4 increases the risk of Alzheimer's disease (AD). While transporting cholesterol is a primary function, apoE also regulates amyloid-β (Aβ) metabolism, aggregation, and deposition. Although earlier work suggests that different affinities of apoE isoforms to Aβ might account for their effects on Aβ clearance, recent studies indicate that apoE also competes with Aβ for cellular uptake through apoE receptors. Thus, several factors probably determine the variable effects apoE has on Aβ. In this Review, we examine biochemical, structural, and functional studies and propose testable models that address the complex mechanisms underlying apoE-Aβ interaction and how apoE4 may increase AD risk and also serve as a target pathway for therapy.
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Affiliation(s)
- Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen 361005, China
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen 361005, China.
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12
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Floden AM, Combs CK. Microglia demonstrate age-dependent interaction with amyloid-β fibrils. J Alzheimers Dis 2011; 25:279-93. [PMID: 21403390 DOI: 10.3233/jad-2011-101014] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Alzheimer's disease (AD) is an age-associated disease characterized by increased accumulation of extracellular amyloid-β (Aβ) plaques within the brain. Histological examination has also revealed profound microglial activation in diseased brains often in association with these fibrillar peptide aggregates. The paradoxical presence of increased, reactive microglia yet accumulating extracellular debris suggests that these cells may be phagocytically compromised during disease. Prior work has demonstrated that primary microglia from adult mice are unable to phagocytose fibrillar Aβ1-42 in vitro when compared to microglia cultured from early postnatal animals. These data suggest that microglia undergo an age-associated decrease in microglial ability to interact with Aβ fibrils. In order to better define a temporal profile of microglia-Aβ interaction, acutely isolated, rather than cultured, microglia from 2 month, 6 month, and postnatal day 0 C57BL/6 mice were compared. Postnatal day 0 microglia demonstrated a CD47 dependent ability to phagocytose Aβ fibrils that was lost by 6 months. This corresponded with the ability of postnatal day 0 but not adult microglia to decrease Aβ immunoreactive plaque load from AD sections in vitro. In spite of limited Aβ uptake ability, adult microglia had functional phagocytic uptake of bacterial bioparticles and demonstrated the ability to adhere to both Aβ plaques and in vitro fibrillized Aβ. These data demonstrate a temporal profile of specifically Aβ-microglia interaction with a critical developmental period at 6 months in which cells remain able to interact with Aβ fibrils but lose their ability to phagocytose it.
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Affiliation(s)
- Angela Marie Floden
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203-9037, USA
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Koistinaho J, Malm T, Goldsteins G. Glycogen synthase kinase-3β: a mediator of inflammation in Alzheimer's disease? Int J Alzheimers Dis 2011; 2011:129753. [PMID: 21629736 PMCID: PMC3100542 DOI: 10.4061/2011/129753] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/04/2011] [Indexed: 02/03/2023] Open
Abstract
Proliferation and activation of microglial cells is a neuropathological characteristic of brain injury and neurodegeneration, including Alzheimer's disease. Microglia act as the first and main form of immune defense in the nervous system. While the primary function of microglia is to survey and maintain the cellular environment optimal for neurons in the brain parenchyma by actively scavenging the brain for damaged brain cells and foreign proteins or particles, sustained activation of microglia may result in high production of proinflammatory mediators that disturb normal brain functions and even cause neuronal injury. Glycogen synthase kinase-3β has been recently identified as a major regulator of immune system and mediates inflammatory responses in microglia. Glycogen synthase kinase-3β has been extensively investigated in connection to tau and amyloid β toxicity, whereas reports on the role of this enzyme in neuroinflammation in Alzheimer's disease are negligible. Here we review and discuss the role of glycogen synthase-3β in immune cells in the context of Alzheimer's disease pathology.
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Affiliation(s)
- Jari Koistinaho
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
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Choucair-Jaafar N, Laporte V, Levy R, Poindron P, Lombard Y, Gies JP. Complement receptor 3 (CD11b/CD18) is implicated in the elimination of β-amyloid peptides. Fundam Clin Pharmacol 2011; 25:115-22. [PMID: 20199584 DOI: 10.1111/j.1472-8206.2010.00811.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Microglia are the professional phagocytes of the brain and express phagocytic receptors such as complement receptor 3 (CR3 or CD11b/CD18). Using mimics of the amyloid deposit made of heat-killed yeasts coated with either Aβ 1-40 or Aβ 1-42, we were able to study how microglia interacted with and ingested these particles in vitro. We have shown previously that the low density lipoprotein receptor-related protein (LRP) is largely implied in the phagocytosis of Aβ 1-42-opsonized heat-killed yeasts and partly in that of Aβ 1-40-opsonized heat-killed yeasts. Here, we report that antibodies against CD11b or CD18 reduced the uptake of the artificial amyloid deposit by microglial cell showing that CR3 is involved in the mechanism. Moreover, a concomitant inhibition of LRP and CR3 completely blocked the ingestion of both kinds of particles suggesting that no other receptors participate to this mechanism.
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Affiliation(s)
- Nada Choucair-Jaafar
- UMR 7213, Université de Strasbourg, CNRS, 74 route du Rhin, 67401 Illkirch, France.
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15
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Malm T, Koistinaho M, Muona A, Magga J, Koistinaho J. The role and therapeutic potential of monocytic cells in Alzheimer's disease. Glia 2010; 58:889-900. [PMID: 20155817 DOI: 10.1002/glia.20973] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is a dementing neurodegenerative disorder without a cure. The abnormal parenchymal accumulation of beta-amyloid (Abeta) is associated with inflammatory reactions involving microglia and astrocytes. Increased levels of Abeta and Abeta deposition in the brain are thought to cause neuronal dysfunction and underlie dementia. Microglia, the brain resident cells of monocytic origin, have a potential ability to phagocytose Abeta but they also react to Abeta by increased production of proinflammatory toxic agents. Microglia originate from hemangioblastic mesoderm during early embryonic stages and from bone marrow (BM)-derived monocytic cells that home the brain throughout the neonatal stage of development. Recent studies indicate that BM or blood-derived monocytes are recruited to the diseased AD brain, associate with the Abeta depositions, and are more efficient phagocytes of Abeta compared with resident microglia. The clearance of Abeta deposition by these cells has been recently under intensive investigation and can occur through several different mechanisms. Importantly, peripheral monocytic cells of patients with AD appear to be deficient in clearing Abeta. This review will summarize the findings on the role of blood-derived cells in AD and discuss their therapeutic potential for treating patients suffering from this devastating disease.
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Affiliation(s)
- Tarja Malm
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, Biocenter Kuopio, University of Eastern Finland, P.O. Box 1627, Kuopio, Finland
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16
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Brandenburg LO, Konrad M, Wruck CJ, Koch T, Lucius R, Pufe T. Functional and physical interactions between formyl-peptide-receptors and scavenger receptor MARCO and their involvement in amyloid beta 1-42-induced signal transduction in glial cells. J Neurochem 2010; 113:749-60. [PMID: 20141570 DOI: 10.1111/j.1471-4159.2010.06637.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent studies suggest that the chemotactic G protein-coupled receptor formyl-peptide-receptor-like-1 (FPRL1) or the scavenger receptor MARCO (macrophage receptor with collagenous structure) plays an essential role in the inflammatory response of host defense mechanisms and neurodegenerative disorders such as Alzheimer's disease. We therefore analyzed the involvement of FPRL1 and MARCO in amyloid beta1-42 (Abeta1-42)-induced signalling by extracellular-signal regulated kinases 1/2 (ERK1/2) phosphorylation and cAMP level measurement in glial cells (astrocytes and microglia) and in transfected HEK293 cells. Receptors were inhibited by small interference RNA and the consequences in Abeta1-42- and MARCO agonist fucoidan-induced signal transduction were determined. Receptor deactivation by antagonists or small interference RNA verified the importance of FPRL1 for Abeta1-42-mediated signal transduction by ERK1/2 phosphorylation and cAMP level measurement in glial cells. Furthermore, for the first time, we have demonstrated a functional interaction between FPRL1 and scavenger receptors in fucoidan-mediated signalling by ERK1/2 phosphorylation and cAMP level measurement. In addition, co-immunoprecipitation data and fluorescence microscopy measurements revealed a physical interaction between FPR, FPRL1 and MARCO. These results suggest that FPRL1 plays a pivotal role for Abeta1-42-induced signal transduction in glial cells and the interaction with MARCO could explain the broad ligand spectrum of formyl peptide receptors.
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Affiliation(s)
- Lars-Ove Brandenburg
- Department of Anatomy and Cell Biology, RWTH Aachen University, Aachen, Germany.
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17
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Niederhoffer N, Levy R, Sick E, Andre P, Coupin G, Lombard Y, Gies JP. Amyloid beta peptides trigger CD47-dependent mast cell secretory and phagocytic responses. Int J Immunopathol Pharmacol 2009; 22:473-83. [PMID: 19505377 DOI: 10.1177/039463200902200224] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mast cells are found in the brain, where they contribute to immune responses. They have been implicated in multiple sclerosis, but their potential role in Alzheimers disease (AD), another inflammatory disease of the central nervous system, remains elusive. In the present study, we examined mast cell responses to amyloid beta (Abeta) peptides 1-40 and 1-42, the major components of the Alzheimer amyloid plaques. Rat peritoneal mast cells were used as experimental model for human brain serosal mast cells. Fibrillar Abeta1-40 and Ami1-42 peptides induced concentration-dependent exocytosis, as assessed by measurement of histamine secretion; exocytosis was reduced by pre-treatment with pertussis toxin and with antibodies against the CD47 receptor and the beta1-integrin subunit. Fibrillar Abeta1-40 and Abeta1- 42 peptides coated on heat-inactivated yeast particles and soluble fibrillar Abeta1-40 and Abeta1-42 peptides were also recognized and phagocyted by mast cells. Uptake of the peptides was decreased in the presence of 4N1, a peptide agonist of the CD47 receptor, but remained unchanged in the presence of 4NGG, a peptide derived from 4N1 which does not bind to CD47. Non-fibrillar forms of Abeta1-40 and 1-42 peptides were unable to elicit mast cell responses. These results show that fibrillar Abeta peptides can trigger mast cells and elicit exocytosis and phagocytosis. The Abeta-induced activation of mast cells operates through a CD47/beta1-integrin membrane complex coupled with Gi-protein. The present data support the hypothesis that mast cells, similarly to microglial cells, could play a major role in AD pathogenesis.
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Affiliation(s)
- N Niederhoffer
- Université de Strasbourg, CNRS UMR 7213, Laboratoire de Biophotonique et Pharmacologie, Faculté de Pharmacie, Illkirch, France.
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18
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Metallothionein Treatment Attenuates Microglial Activation and Expression of Neurotoxic Quinolinic Acid Following Traumatic Brain Injury. Neurotox Res 2009; 15:381-9. [DOI: 10.1007/s12640-009-9044-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 02/19/2009] [Accepted: 03/10/2009] [Indexed: 10/20/2022]
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Brandenburg LO, Konrad M, Wruck C, Koch T, Pufe T, Lucius R. Involvement of formyl-peptide-receptor-like-1 and phospholipase D in the internalization and signal transduction of amyloid beta 1-42 in glial cells. Neuroscience 2008; 156:266-76. [PMID: 18723082 DOI: 10.1016/j.neuroscience.2008.07.042] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 07/03/2008] [Accepted: 07/22/2008] [Indexed: 10/21/2022]
Abstract
Recent studies suggest that the formyl-peptide-receptor-like-1 (FPRL1) plays an essential role in the inflammatory responses of host defense mechanisms and neurodegenerative disorders such as Alzheimer's disease (AD). We therefore analyzed whether amyloid beta1-42 (Abeta1-42) increased the activity of phospholipase D (PLD) via FPRL1, which is an enzyme involved in the secretion, endocytosis and receptor signaling. PLD activity was determined using a transphosphatidylation assay. The internalization of Abeta1-42 via FPRL1 was visualized using fluorescence microscopy and quantified by ELISA (Enzyme Linked Immunosorbent Assay). Determining receptor activity by extracellular-signal regulated kinases 1/2 (ERK1/2) phosphorylation and cAMP level measurement verified the Abeta1-42-induced activation of FPRL1. We were able to show that Abeta1-42 is rapidly internalized via FPRL1 in astrocytes and microglia. PLD was additionally activated by Abeta1-42 and via FPRL1 in rat glial cells. Furthermore, the ERK1/2 phosphorylation by FPRL1 agonists was dependent on the PLD product phosphatidic acid (PA). Together, these data suggest that PLD plays an important role in the regulation of Abeta1-42-induced endocytosis and FPRL1 receptor signaling.
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Affiliation(s)
- L-O Brandenburg
- Department of Anatomy and Cell Biology, University Hospital RWTH Aachen, Wendlingweg 2, 52074 Aachen, Germany.
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20
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Wilson MR, Yerbury JJ, Poon S. Potential roles of abundant extracellular chaperones in the control of amyloid formation and toxicity. ACTA ACUST UNITED AC 2008; 4:42-52. [DOI: 10.1039/b712728f] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Schulz B, Liebisch G, Grandl M, Werner T, Barlage S, Schmitz G. β-Amyloid (Aβ40, Aβ42) binding to modified LDL accelerates macrophage foam cell formation. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:1335-44. [PMID: 17881287 DOI: 10.1016/j.bbalip.2007.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 08/01/2007] [Accepted: 08/02/2007] [Indexed: 11/26/2022]
Abstract
Apart from its role as a risk factor in arteriosclerosis, plasma cholesterol is increasingly recognized to play a major role in the pathogenesis of Alzheimer's disease (AD). Moreover, alterations of intracellular cholesterol metabolism in neuronal and vascular cells are of considerable importance for the understanding of AD. Cellular cholesterol accumulation enhances the deposition of insoluble beta-amyloid peptides, which is considered a hallmark in the pathogenesis of AD. In order to test the hypothesis, whether exogenous beta-amyloid peptides (Abeta42, Abeta40) might contribute to cellular cholesterol accumulation by opsonization of lipoproteins, we compared the binding and uptake of native LDL, enzymatically modified LDL (E-LDL), copper oxidized LDL (Ox-LDL) and HDL as control, preincubated either in the absence or presence of Abeta42 or Abeta40, by human monocytes or monocyte-derived macrophages. Incubation of monocytes and macrophages with Abeta-lipoprotein-complexes lead to increased cellular free and esterified cholesterol when compared to non-opsonized lipoproteins, except for HDL. Furthermore, the cellular uptake of these complexes regulated Abeta-receptors such as FPRL-1 or LRP/CD91. In summary, our results suggest that Abeta42 and Abeta40 act as potent opsonins for LDL, E-LDL and Ox-LDL and enhance cellular cholesterol accumulation as well as Abeta-deposition in vessel wall macrophages.
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Affiliation(s)
- Berta Schulz
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, 93042 Regensburg, Germany
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Elliott DA, Kim WS, Jans DA, Garner B. Apoptosis induces neuronal apolipoprotein-E synthesis and localization in apoptotic bodies. Neurosci Lett 2007; 416:206-10. [PMID: 17320289 DOI: 10.1016/j.neulet.2007.02.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Revised: 02/01/2007] [Accepted: 02/05/2007] [Indexed: 10/23/2022]
Abstract
Neuronal apoptosis is crucial for central nervous system development and also contributes to neurodegenerative disease. Apolipoprotein-E (apoE) regulates brain lipid transport and specific neuronal functions and previous research, investigating non-neuronal cell types, identified an association between apoptosis and increased apoE expression. In the present study we used the human SK-N-SH neuronal cell line to investigate potential changes in apoE expression during apoptosis which occurs as a consequence of extended culture (up to 5 days) without replenishing trophic factors. Standard and real-time PCR analysis indicated a significant 6-fold increase in apoE mRNA after 3 days which was correlated with caspase-3 activation, TUNEL positivity and the formation of apoptotic bodies. ApoE protein levels were low in the absence of apoptosis but increased by 8-fold when apoptosis was induced. Analysis of cellular debris that accumulated in the culture supernatants indicated that apoE levels became progressively concentrated in apoptotic bodies. These data indicate that apoE is up-regulated during neuronal apoptosis and raise the possibility that apoE may play a role in the clearance of apoptotic bodies through apoE-receptor interactions.
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Affiliation(s)
- David A Elliott
- Prince of Wales Medical Research Institute, Randwick, NSW 2031, Australia
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Logan MA, Freeman MR. The scoop on the fly brain: glial engulfment functions in Drosophila. NEURON GLIA BIOLOGY 2007; 3:63-74. [PMID: 18172512 PMCID: PMC2171361 DOI: 10.1017/s1740925x07000646] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Glial cells provide support and protection for neurons in the embryonic and adult brain, mediated in part through the phagocytic activity of glia. Glial cells engulf apoptotic cells and pruned neurites from the developing nervous system, and also clear degenerating neuronal debris from the adult brain after neural trauma. Studies indicate that Drosophila melanogaster is an ideal model system to elucidate the mechanisms of engulfment by glia. The recent studies reviewed here show that many features of glial engulfment are conserved across species and argue that work in Drosophila will provide valuable cellular and molecular insight into glial engulfment activity in mammals.
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Affiliation(s)
- Mary A Logan
- University of Massachusetts Medical School, Department of Neurobiology 770P, 364 Plantation Street, Worcester, MA 01605, USA.
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