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Fruhwürth S, Zetterberg H, Paludan SR. Microglia and amyloid plaque formation in Alzheimer's disease - Evidence, possible mechanisms, and future challenges. J Neuroimmunol 2024; 390:578342. [PMID: 38640827 DOI: 10.1016/j.jneuroim.2024.578342] [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: 02/01/2024] [Revised: 03/21/2024] [Accepted: 04/03/2024] [Indexed: 04/21/2024]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive decline that severely affects patients and their families. Genetic and environmental risk factors, such as viral infections, synergize to accelerate the aging-associated neurodegeneration. Genetic risk factors for late-onset AD (LOAD), which accounts for most AD cases, are predominantly implicated in microglial and immune cell functions. As such, microglia play a major role in formation of amyloid beta (Aβ) plaques, the major pathological hallmark of AD. This review aims to provide an overview of the current knowledge regarding the role of microglia in Aβ plaque formation, as well as their impact on morphological and functional diversity of Aβ plaques. Based on this discussion, we seek to identify challenges and opportunities in this field with potential therapeutic implications.
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Affiliation(s)
- Stefanie Fruhwürth
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden; Department of Neurodegenerative Disease, Institute of Neurology, University College London Queen Square, London, UK; UK Dementia Research Institute at UCL, London, UK; Hong Kong Center for Neurodegenerative Diseases, Clear Water Bay, Hong Kong, China; Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, USA
| | - Søren R Paludan
- Department of Rheumatology and Inflammatory Research, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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2
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Bedoya-Guzmán FA, Pacheco-Herrero M, Salomon-Cruz ID, Barrera-Sandoval AM, Gutierrez Vargas JA, Villamil-Ortiz JG, Villegas Lanau CA, Arias-Londoño JD, Area-Gomez E, Cardona Gomez GP. BACE1 and SCD1 are associated with neurodegeneration. Front Aging Neurosci 2023; 15:1194203. [PMID: 37744400 PMCID: PMC10516302 DOI: 10.3389/fnagi.2023.1194203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 08/03/2023] [Indexed: 09/26/2023] Open
Abstract
Introduction Proteolytic processing of amyloid protein precursor by β-site secretase enzyme (BACE1) is dependent on the cellular lipid composition and is affected by endomembrane trafficking in dementia and Alzheimer's disease (AD). Stearoyl-CoA desaturase 1 (SCD1) is responsible for the synthesis of fatty acid monounsaturation (MUFAs), whose accumulation is strongly associated with cognitive dysfunction. Methods In this study, we analyzed the relationship between BACE1 and SCD1 in vivo and in vitro neurodegenerative models and their association in familial AD (FAD), sporadic AD (SAD), and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) using microscopy, biochemical, and mass SPECT approach. Results Our findings showed that BACE1 and SCD1 immunoreactivities were increased and colocalized in astrocytes of the hippocampus in a rat model of global cerebral ischemia (2-VO). A synergistic effect of double BACE1/SCD1 silencing on the recovery of motor and cognitive functions was obtained. This neuroprotective regulation involved the segregation of phospholipids (PLs) associated with polyunsaturated fatty acids in the hippocampus, cerebrospinal fluid, and serum. The double silencing in the sham and ischemic groups was stronger in the serum, inducing an inverse ratio between total phosphatydilcholine (PC) and lysophosphatidylcholine (LPC), represented mainly by the reduction of PC 38:4 and PC 36:4 and an increase in LPC 16:0 and LPC 18:0. Furthermore, PC 38:4 and PC:36:4 levels augmented in pathological conditions in in vitro AD models. BACE1 and SCD1 increases were confirmed in the hippocampus of FAD, SAD, and CADASIL. Conclusion Therefore, the findings suggest a novel convergence of BACE-1 and SCD1 in neurodegeneration, related to pro-inflammatory phospholipids.
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Affiliation(s)
- Ferley A. Bedoya-Guzmán
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
| | - Mar Pacheco-Herrero
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
- Neuroscience Research Laboratory, Faculty of Health Sciences, Pontificia Universidad Católica Madre y Maestra, Santiago de los Caballeros, Dominican Republic
| | - Ivan Daniel Salomon-Cruz
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
| | - Angela Maria Barrera-Sandoval
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
| | - Johanna Andrea Gutierrez Vargas
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
- Grupo de Investigación en Salud del Adulto Mayor (GISAM), Corporación Universitaria Remington, Medellín, Colombia
| | - Javier Gustavo Villamil-Ortiz
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
| | - Carlos Andres Villegas Lanau
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
| | | | - Estela Area-Gomez
- Department of Neurology, Columbia University Medical Center, New York, NY, United States
| | - Gloria Patricia Cardona Gomez
- Faculty of Medicine University of Antioquia, Cellular and Molecular Neurobiology Area and Neurobank, Group of Neuroscience (GNA), Medellín, Colombia
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3
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Cai W, Li L, Sang S, Pan X, Zhong C. Physiological Roles of β-amyloid in Regulating Synaptic Function: Implications for AD Pathophysiology. Neurosci Bull 2023; 39:1289-1308. [PMID: 36443453 PMCID: PMC10387033 DOI: 10.1007/s12264-022-00985-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 09/02/2022] [Indexed: 11/29/2022] Open
Abstract
The physiological functions of endogenous amyloid-β (Aβ), which plays important role in the pathology of Alzheimer's disease (AD), have not been paid enough attention. Here, we review the multiple physiological effects of Aβ, particularly in regulating synaptic transmission, and the possible mechanisms, in order to decipher the real characters of Aβ under both physiological and pathological conditions. Some worthy studies have shown that the deprivation of endogenous Aβ gives rise to synaptic dysfunction and cognitive deficiency, while the moderate elevation of this peptide enhances long term potentiation and leads to neuronal hyperexcitability. In this review, we provide a new view for understanding the role of Aβ in AD pathophysiology from the perspective of physiological meaning.
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Affiliation(s)
- Wenwen Cai
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Linxi Li
- Basic Medical College, Nanchang University, Nanchang, 330031, China
| | - Shaoming Sang
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Xiaoli Pan
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
| | - Chunjiu Zhong
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science & Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China.
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4
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Kumar R, Kumar R, Sharma N, Khurana N, Singh SK, Satija S, Mehta M, Vyas M. Pharmacological evaluation of bromelain in mouse model of Alzheimer's disease. Neurotoxicology 2022; 90:19-34. [PMID: 35219781 DOI: 10.1016/j.neuro.2022.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 01/25/2022] [Accepted: 02/21/2022] [Indexed: 10/19/2022]
Abstract
The current study elucidates pharmacological evaluation of bromelain as a bioactive compound obtain from pineapple stem belongs to family Bromeliaceae in AlCl3 and D - galactose induced mice. In mice, co-administration of AlCl3 at dose 5 mg/kg b.w., via the oral route, and D - galactose at dose 60 mg/kg b.w., via intraperitoneal route for 90 days resulted in cognitive impairment, spatial learning, and memory deficits, as well as neurotoxicity. However, 30 consecutive days, treatments via an intraperitoneal route with bromelain low dose (Brm L) at dose 10 mg/kg b.w., bromelain high dose (Brm H) at dose 20 mg/kg b.w., donepezil (Dnpz) at dose 2 mg/kg b.w., and Brm L + Dnpz at doses 10, 2 mg/kg b.w. were considerably reversed the effect of AlCl3 and D - galactose induced AD mice. Consequences of behavioral parameters (Morris water maze, elevated plus maze and locomotor), biochemical estimation (MDA, GSH, SOD, CAT, Nitrite and AChE), and ELISA tests (mouse BACE, Aβ1 - 42, TNF-α, IL-6, and BDNF) confirmed significant (p < 0.05) neuroprotective effect of treatments in AlCl3 and D - galactose induced mice. Additionally, hematoxylin and eosin staining of the cerebral cortex and the hippocampus exposed eosinophilic lesions and hyperchromatic nuclei in AD mice, but these neurodegenerative effects were eliminated by Brm L, Brm H, Dnpz, and Brm L + Dnpz treatments. Thus, bromelain alone and in combination with donepezil prevent AlCl3 and D - galactose induced spatial learning and memory deficits, as well as cognitive impairment, by increasing cholinergic activity and synaptic plasticity, as well as reducing oxidative damage, neuroinflammation, Aβ 1-42 aggregations, and histopathological damage, according to our findings. The present study consequences indicate that bromelain alone and in combination with donepezil appears to have neuroprotective properties. Henceforward, this may be a promising treatment option for Alzheimer's disease.
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Affiliation(s)
- Rakesh Kumar
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India
| | - Rajan Kumar
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India
| | - Neha Sharma
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India
| | - Navneet Khurana
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India.
| | - Sachin Kumar Singh
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India
| | - Saurabh Satija
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India
| | - Meenu Mehta
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India
| | - Manish Vyas
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India
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5
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Vargas-George S, Dave KR. Models of cerebral amyloid angiopathy-related intracerebral hemorrhage. BRAIN HEMORRHAGES 2022. [DOI: 10.1016/j.hest.2022.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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6
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Kumar R, Kumar R, Sharma N, Khurana N. Ameliorative effect of myrcene in mouse model of Alzheimer's disease. Eur J Pharmacol 2021; 911:174529. [PMID: 34592305 DOI: 10.1016/j.ejphar.2021.174529] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 10/20/2022]
Abstract
Myrcene (Myr) has been reported to show neuroprotective effects in cerebral ischemia. In this research work, we investigated the Myr effect on neurobehavioural, and neuropathological alteration in mice induced by Aluminium trichloride (AlCl3) and D - galactose. The administration of AlCl3 (5 mg/kg; p. o.), and D - galactose (60 mg/kg; i. p.) for 90 days in mice resulted in spatial learning and memory deficits, cognitive decline, as well as neurotoxicity. The treatments with Myr low dose (100 mg/kg), Myr high dose (200 mg/kg), donepezil (2 mg/kg), and Myr low dose + donepezil (100 + 2 mg/kg) were administered via intraperitoneal route for 30 days significantly reversed the neurobehavioral, and neuropathological effects of AlCl3 and D - galactose in mice. The results of behavioural tests such as Morris water maze, elevated plus maze, and locomotor; biochemical analysis such as malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), nitrite, and acetylcholinesterase (AChE); and ELISA tests such as mouse β - secretase (BACE), amyloid-beta peptide1-42 (Aβ1 - 42), tumor necrosis factor - α (TNF-α), interleukin - 6 (IL-6), and brain-derived neurotrophic factor (BDNF) demonstrated a significant (p < 0.05) neuroprotective effect of the Myr and donepezil co-treatments. In addition, hematoxylin and eosin staining of the cerebral cortex and hippocampus revealed eosinophilic lesions and hyperchromatic nuclei in Alzheimer's disease mice, but treatments with Myr low dose, Myr high dose, donepezil, and Myr low dose + donepezil reversed these neurodegenerative effects. Myr showed these activities by enhancing synaptic plasticity and cholinergic activity, as well as reducing oxidative damage, neuroinflammation, Aβ1-42 aggregations, and histopathological damage. Myr alone and in combination with donepezil may serve as a potential candidate for the treatment of Alzheimer's disease.
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Affiliation(s)
- Rakesh Kumar
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Rajan Kumar
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Neha Sharma
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Navneet Khurana
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, 144411, Punjab, India.
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7
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Wu Q, Cortez L, Kamali-Jamil R, Sim V, Wille H, Kar S. Implications of exosomes derived from cholesterol-accumulated astrocytes in Alzheimer's disease pathology. Dis Model Mech 2021; 14:dmm048929. [PMID: 34524402 PMCID: PMC8560497 DOI: 10.1242/dmm.048929] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 09/06/2021] [Indexed: 12/25/2022] Open
Abstract
Amyloid β (Aβ) peptides generated from the amyloid precursor protein (APP) play a critical role in the development of Alzheimer's disease (AD) pathology. Aβ-containing neuronal exosomes, which represent a novel form of intercellular communication, have been shown to influence the function/vulnerability of neurons in AD. Unlike neurons, the significance of exosomes derived from astrocytes remains unclear. In this study, we evaluated the significance of exosomes derived from U18666A-induced cholesterol-accumulated astrocytes in the development of AD pathology. Our results show that cholesterol accumulation decreases exosome secretion, whereas lowering cholesterol increases exosome secretion, from cultured astrocytes. Interestingly, exosomes secreted from U18666A-treated astrocytes contain higher levels of APP, APP-C-terminal fragments, soluble APP, APP secretases and Aβ1-40 than exosomes secreted from control astrocytes. Furthermore, we show that exosomes derived from U18666A-treated astrocytes can lead to neurodegeneration, which is attenuated by decreasing Aβ production or by neutralizing exosomal Aβ peptide with an anti-Aβ antibody. These results, taken together, suggest that exosomes derived from cholesterol-accumulated astrocytes can play an important role in trafficking APP/Aβ peptides and influencing neuronal viability in the affected regions of the AD brain.
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Affiliation(s)
- Qi Wu
- Department of Medicine (Neurology), University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Leonardo Cortez
- Department of Medicine (Neurology), University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Razieh Kamali-Jamil
- Department of Biochemistry, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Valerie Sim
- Department of Medicine (Neurology), University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Holger Wille
- Department of Biochemistry, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Satyabrata Kar
- Department of Medicine (Neurology), University of Alberta, Edmonton, AB T6G 2G3, Canada
- Department of Biochemistry, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB T6G 2G3, Canada
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Brookhouser N, Raman S, Frisch C, Srinivasan G, Brafman DA. APOE2 mitigates disease-related phenotypes in an isogenic hiPSC-based model of Alzheimer's disease. Mol Psychiatry 2021; 26:5715-5732. [PMID: 33837271 PMCID: PMC8501163 DOI: 10.1038/s41380-021-01076-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 02/26/2021] [Accepted: 03/23/2021] [Indexed: 02/02/2023]
Abstract
Genome-wide association studies (GWAS) have identified polymorphism in the Apolipoprotein E gene (APOE) to be the most prominent risk factor for Alzheimer's disease (AD). Compared to individuals homozygous for the APOE3 variant, individuals with the APOE4 variant have a significantly elevated risk of AD. On the other hand, longitudinal studies have shown that the presence of the APOE2 variant reduces the lifetime risk of developing AD by 40 percent. While there has been significant research that has identified the risk-inducing effects of APOE4, the underlying mechanisms by which APOE2 influences AD onset and progression have not been extensively explored. In this study, we utilize an isogenic human induced pluripotent stem cell (hiPSC)-based system to demonstrate that conversion of APOE3 to APOE2 greatly reduced the production of amyloid-beta (Aβ) peptides in hiPSC-derived neural cultures. Mechanistically, analysis of pure populations of neurons and astrocytes derived from these neural cultures revealed that mitigating effects of APOE2 are mediated by cell autonomous and non-autonomous effects. In particular, we demonstrated the reduction in Aβ is potentially driven by a mechanism related to non-amyloidogenic processing of amyloid precursor protein (APP), suggesting a gain of the protective function of the APOE2 variant. Together, this study provides insights into the risk-modifying effects associated with the APOE2 allele and establishes a platform to probe the mechanisms by which APOE2 enhances neuroprotection against AD.
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Affiliation(s)
- Nicholas Brookhouser
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
- Graduate Program in Clinical Translational Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Sreedevi Raman
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - Carlye Frisch
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - Gayathri Srinivasan
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - David A Brafman
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
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9
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Wang H, Kulas JA, Wang C, Holtzman DM, Ferris HA, Hansen SB. Regulation of beta-amyloid production in neurons by astrocyte-derived cholesterol. Proc Natl Acad Sci U S A 2021; 118:e2102191118. [PMID: 34385305 PMCID: PMC8379952 DOI: 10.1073/pnas.2102191118] [Citation(s) in RCA: 113] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by the presence of amyloid β (Aβ) plaques, tau tangles, inflammation, and loss of cognitive function. Genetic variation in a cholesterol transport protein, apolipoprotein E (apoE), is the most common genetic risk factor for sporadic AD. In vitro evidence suggests that apoE links to Aβ production through nanoscale lipid compartments (lipid clusters), but its regulation in vivo is unclear. Here, we use superresolution imaging in the mouse brain to show that apoE utilizes astrocyte-derived cholesterol to specifically traffic neuronal amyloid precursor protein (APP) in and out of lipid clusters, where it interacts with β- and γ-secretases to generate Aβ-peptide. We find that the targeted deletion of astrocyte cholesterol synthesis robustly reduces amyloid and tau burden in a mouse model of AD. Treatment with cholesterol-free apoE or knockdown of cholesterol synthesis in astrocytes decreases cholesterol levels in cultured neurons and causes APP to traffic out of lipid clusters, where it interacts with α-secretase and gives rise to soluble APP-α (sAPP-α), a neuronal protective product of APP. Changes in cellular cholesterol have no effect on α-, β-, and γ-secretase trafficking, suggesting that the ratio of Aβ to sAPP-α is regulated by the trafficking of the substrate, not the enzymes. We conclude that cholesterol is kept low in neurons, which inhibits Aβ accumulation and enables the astrocyte regulation of Aβ accumulation by cholesterol signaling.
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Affiliation(s)
- Hao Wang
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458
- Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, Jupiter, FL 33458
| | - Joshua A Kulas
- Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, VA 22908
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22908
| | - Chao Wang
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110
| | - David M Holtzman
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110
| | - Heather A Ferris
- Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, VA 22908;
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22908
| | - Scott B Hansen
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458;
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458
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10
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Xu P, Chang JC, Zhou X, Wang W, Bamkole M, Wong E, Bettayeb K, Jiang LL, Huang T, Luo W, Xu H, Nairn AC, Flajolet M, Ip NY, Li YM, Greengard P. GSAP regulates lipid homeostasis and mitochondrial function associated with Alzheimer's disease. J Exp Med 2021; 218:e20202446. [PMID: 34156424 PMCID: PMC8222926 DOI: 10.1084/jem.20202446] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 04/22/2021] [Accepted: 05/26/2021] [Indexed: 11/04/2022] Open
Abstract
Biochemical, pathogenic, and human genetic data confirm that GSAP (γ-secretase activating protein), a selective γ-secretase modulatory protein, plays important roles in Alzheimer's disease (AD) and Down's syndrome. However, the molecular mechanism(s) underlying GSAP-dependent pathogenesis remains largely elusive. Here, through unbiased proteomics and single-nuclei RNAseq, we identified that GSAP regulates multiple biological pathways, including protein phosphorylation, trafficking, lipid metabolism, and mitochondrial function. We demonstrated that GSAP physically interacts with the Fe65-APP complex to regulate APP trafficking/partitioning. GSAP is enriched in the mitochondria-associated membrane (MAM) and regulates lipid homeostasis through the amyloidogenic processing of APP. GSAP deletion generates a lipid environment unfavorable for AD pathogenesis, leading to improved mitochondrial function and the rescue of cognitive deficits in an AD mouse model. Finally, we identified a novel GSAP single-nucleotide polymorphism that regulates its brain transcript level and is associated with an increased AD risk. Together, our findings indicate that GSAP impairs mitochondrial function through its MAM localization and that lowering GSAP expression reduces pathological effects associated with AD.
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Affiliation(s)
- Peng Xu
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY
| | - Jerry C. Chang
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Xiaopu Zhou
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Hong Kong, China
- Hong Kong Center for Neurodegenerative Diseases, Hong Kong Science and Technology Parks, Hong Kong, China
- Guangdong Provincial Key Laboratory of Brain Science, Disease, and Drug Development, Shenzhen–Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, Guangdong, China
| | - Wei Wang
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY
| | - Michael Bamkole
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY
| | - Eitan Wong
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Karima Bettayeb
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY
| | - Lu-Lin Jiang
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Timothy Huang
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Wenjie Luo
- Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY
| | - Huaxi Xu
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Angus C. Nairn
- Department of Psychiatry, Yale School of Medicine, Connecticut Mental Health Center, New Haven, CT
| | - Marc Flajolet
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY
| | - Nancy Y. Ip
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Hong Kong, China
- Hong Kong Center for Neurodegenerative Diseases, Hong Kong Science and Technology Parks, Hong Kong, China
- Guangdong Provincial Key Laboratory of Brain Science, Disease, and Drug Development, Shenzhen–Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, Guangdong, China
| | - Yue-Ming Li
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY
- Program of Pharmacology and Neurosciences, Weill Graduate School of Medical Sciences of Cornell University, New York, NY
| | - Paul Greengard
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY
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Syeda T, Cannon JR. Environmental exposures and the etiopathogenesis of Alzheimer's disease: The potential role of BACE1 as a critical neurotoxic target. J Biochem Mol Toxicol 2021; 35:e22694. [PMID: 33393683 DOI: 10.1002/jbt.22694] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 12/18/2020] [Accepted: 12/22/2020] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD) is a major public health crisis due to devastating cognitive symptoms, a lack of curative treatments, and increasing prevalence. Most cases are sporadic (>95% of cases) after the age of 65 years, implicating an important role of environmental factors in disease pathogenesis. Environmental neurotoxicants have been implicated in neurodegenerative disorders including Parkinson's Disease and AD. Animal models of AD and in vitro studies have shed light on potential neuropathological mechanisms, yet the biochemical and molecular underpinnings of AD-relevant environmental neurotoxicity remain poorly understood. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a potentially critical pathogenic target of environmentally induced neurotoxicity. BACE1 clearly has a critical role in AD pathophysiology: It is required for amyloid beta production and expression and activity of BACE1 are increased in the AD brain. Though the literature on BACE1 in response to environmental insults is limited, current studies, along with extensive AD neurobiology literature suggest that BACE1 deserves attention as an important neurotoxic target. Here, we critically review research on environmental neurotoxicants such as metals, pesticides, herbicides, fungicides, polyfluoroalkyl substances, heterocyclic aromatic amines, advanced glycation end products, and acrolein that modulate BACE1 and potential mechanisms of action. Though more research is needed to clearly understand whether BACE1 is a critical mediator of AD-relevant neurotoxicity, available reports provide convincing evidence that BACE1 is altered by environmental risk factors associated with AD pathology, implying that BACE1 inhibition and its use as a biomarker should be considered in AD management and research.
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Affiliation(s)
- Tauqeerunnisa Syeda
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.,Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, Indiana, USA
| | - Jason R Cannon
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.,Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, Indiana, USA
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12
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Ahmad SS, Kamal MA. Current Updates on the Regulation of Beta-Secretase Movement as a Potential Restorative Focus for Management of Alzheimer's Disease. Protein Pept Lett 2019; 26:579-587. [DOI: 10.2174/0929866526666190405125334] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 03/16/2019] [Accepted: 03/17/2019] [Indexed: 11/22/2022]
Abstract
The most recent decade was described by a developing awareness about the
seriousness of dementia in the field of age-related people. Among the dementias, Alzheimer's
assumes a plentiful role as a result of its amazingly high rate and casualty. A few
pharmacological procedures have been attempted yet at the same time now, Alzheimer continues
being an untreatable malady. The collection of Aβ in the brain is an early poisonous occasion in
the pathogenesis of Alzheimer's disease, which is the most widely recognized type of dementia
correlated with plaques and tangles within the brain. However, the mechanism of the
intraneuronal direction of BACE1 is poorly understood. AD is caused by mutations in one of the
genes that encoding APP, presenilins 1 and 2. Most of the mutations in these genes increase
Aβ42 production. Numerous receptors are associated with initiating Aβ transport and clearance.
Among them, RAGE is an influx transport receptor that binds soluble Aβ and mediates
pathophysiological cellular responses. RAGE additionally intervenes the vehicle of plasma Aβ
over the blood-brain barrier. LRP-1 functions as a clearance receptor for Aβ at the blood-brain
barrier. The regulation of beta-secretase movement is being explored as a potential restorative
focus for treating AD.
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Affiliation(s)
- Syed Sayeed Ahmad
- Department of Bioengineering, Faculty of Engineering, Integral University, Lucknow, India
| | - Mohammad Amjad Kamal
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
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Gaudreault R, Mousseau N. Mitigating Alzheimer’s Disease with Natural Polyphenols: A Review. Curr Alzheimer Res 2019; 16:529-543. [DOI: 10.2174/1567205016666190315093520] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 02/14/2019] [Accepted: 03/13/2019] [Indexed: 11/22/2022]
Abstract
:According to Alzheimer’s Disease International (ADI), nearly 50 million people worldwide were living with dementia in 2017, and this number is expected to triple by 2050. Despite years of research in this field, the root cause and mechanisms responsible for Alzheimer’s disease (AD) have not been fully elucidated yet. Moreover, promising preclinical results have repeatedly failed to translate into patient treatments. Until now, none of the molecules targeting AD has successfully passed the Phase III trial. Although natural molecules have been extensively studied, they normally require high concentrations to be effective; alternately, they are too large to cross the blood-brain barrier (BBB).:In this review, we report AD treatment strategies, with a virtually exclusive focus on green chemistry (natural phenolic molecules). These include therapeutic strategies for decreasing amyloid-β (Aβ) production, preventing and/or altering Aβ aggregation, and reducing oligomers cytotoxicity such as curcumin, (-)-epigallocatechin-3-gallate (EGCG), morin, resveratrol, tannic acid, and other natural green molecules. We also examine whether consideration should be given to potential candidates used outside of medicine and nutrition, through a discussion of two intermediate-sized green molecules, with very similar molecular structures and key properties, which exhibit potential in mitigating Alzheimer’s disease.
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Affiliation(s)
- Roger Gaudreault
- Department of Physics, Universit�© de Montr�©al, Case Postale 6128, Succursale Centre-ville, Montreal (QC), Canada
| | - Normand Mousseau
- Department of Physics, Universit�© de Montr�©al, Case Postale 6128, Succursale Centre-ville, Montreal (QC), Canada
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14
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Hategan A, Masliah E, Nath A. HIV and Alzheimer's disease: complex interactions of HIV-Tat with amyloid β peptide and Tau protein. J Neurovirol 2019; 25:648-660. [PMID: 31016584 DOI: 10.1007/s13365-019-00736-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/15/2019] [Accepted: 02/14/2019] [Indexed: 12/21/2022]
Abstract
In patients infected with the human immunodeficiency virus (HIV), the HIV-Tat protein may be continually produced despite adequate antiretroviral therapy. As the HIV-infected population is aging, it is becoming increasingly important to understand how HIV-Tat may interact with proteins such as amyloid β and Tau which accumulate in the aging brain and eventually result in Alzheimer's disease. In this review, we examine the in vivo data from HIV-infected patients and animal models and the in vitro experiments that show how protein complexes between HIV-Tat and amyloid β occur through novel protein-protein interactions and how HIV-Tat may influence the pathways for amyloid β production, degradation, phagocytosis, and transport. HIV-Tat may also induce Tau phosphorylation through a cascade of cellular processes that lead to the formation of neurofibrillary tangles, another hallmark of Alzheimer's disease. We also identify gaps in knowledge and future directions for research. Available evidence suggests that HIV-Tat may accelerate Alzheimer-like pathology in patients with HIV infection which cannot be impacted by current antiretroviral therapy.
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Affiliation(s)
- Alina Hategan
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg 10; Room 7C-103, 10 Center Drive, Bethesda, MD, 20892, USA
| | - Eliezer Masliah
- Division of Neuroscience, National Institute of Aging, National Institutes of Health, 7201 Wisconsin Ave, Bethesda, MD, 20892, USA
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg 10; Room 7C-103, 10 Center Drive, Bethesda, MD, 20892, USA.
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15
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Wang M, Jing T, Wang X, Yao D. Beta-secretase/BACE1 promotes APP endocytosis and processing in the endosomes and on cell membrane. Neurosci Lett 2018; 685:63-67. [PMID: 30120949 DOI: 10.1016/j.neulet.2018.08.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 08/05/2018] [Accepted: 08/14/2018] [Indexed: 10/28/2022]
Abstract
Amyloid-β proteins deposition and aggregation occur in extracellular space and form neuritic plaques in Alzheimer's disease (AD) brain. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1)/ β-secretase and γ-secretase Presenilin 1 (PSEN1) conduct sequential cleavage of amyloid- β precursor protein (APP) and yield amyloid- β proteins. However the details of the interactions of APP with the enzymes and transportation of catalytic products are unclear. Here we reveal distinctive targeting patterns of the proteins in subcellular organelles in N2A cells. We find all three proteins co-localize in endosomes with APP and PSEN1 co-localize and associate on cell membrane and nucleus. By selectively knocking down BACE1 or PSEN 1 with siRNA, we discover that BACE1 functions as the enzyme initiating the first cleavage step and serves a scaffold for APP and PSEN1 endocytosis. PSEN1 knocking-down only leads to the reduction of BACE1 in cell membrane and nucleus. We conclude that BACE1 facilitates the transportation of APP and formation of the complex with γ-secretase, resulting in the stepwise cleavages of APP. After BACE1 cleavage APP binds to PSEN1 and transfers to cell membrane or nucleus for final processing and amyloid genesis.
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Affiliation(s)
- Mingguang Wang
- Department of Neurology, Xuzhou Children's Hospital, 18 Suti North Road, Xuzhou, 221006, China
| | - Tian Jing
- Department of Neurology, Xuzhou Children's Hospital, 18 Suti North Road, Xuzhou, 221006, China
| | - Xuan Wang
- Department of Neurology, Xuzhou Children's Hospital, 18 Suti North Road, Xuzhou, 221006, China
| | - Dan Yao
- Department of Neurology, Xuzhou Children's Hospital, 18 Suti North Road, Xuzhou, 221006, China.
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Endosomal-Lysosomal Cholesterol Sequestration by U18666A Differentially Regulates Amyloid Precursor Protein (APP) Metabolism in Normal and APP-Overexpressing Cells. Mol Cell Biol 2018. [PMID: 29530923 DOI: 10.1128/mcb.00529-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Amyloid β (Aβ) peptide, derived from amyloid precursor protein (APP), plays a critical role in the development of Alzheimer's disease. Current evidence indicates that altered levels or subcellular distribution of cholesterol can regulate Aβ production and clearance, but it remains unclear how cholesterol sequestration within the endosomal-lysosomal (EL) system can influence APP metabolism. Thus, we evaluated the effects of U18666A, which triggers cholesterol redistribution within the EL system, on mouse N2a cells expressing different levels of APP in the presence or absence of extracellular cholesterol and lipids provided by fetal bovine serum (FBS). Our results reveal that U18666A and FBS differentially increase the levels of APP and its cleaved products, the α-, β-, and η-C-terminal fragments, in N2a cells expressing normal levels of mouse APP (N2awt), higher levels of human wild-type APP (APPwt), or "Swedish" mutant APP (APPsw). The cellular levels of Aβ1-40/Aβ1-42 were markedly increased in U18666A-treated APPwt and APPsw cells. Our studies further demonstrate that APP and its cleaved products are partly accumulated in the lysosomes, possibly due to decreased clearance. Finally, we show that autophagy inhibition plays a role in mediating U18666A effects. Collectively, these results suggest that altered levels and distribution of cholesterol and lipids can differentially regulate APP metabolism depending on the nature of APP expression.
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Jha MK, Kim JH, Song GJ, Lee WH, Lee IK, Lee HW, An SSA, Kim S, Suk K. Functional dissection of astrocyte-secreted proteins: Implications in brain health and diseases. Prog Neurobiol 2017; 162:37-69. [PMID: 29247683 DOI: 10.1016/j.pneurobio.2017.12.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 10/23/2017] [Accepted: 12/08/2017] [Indexed: 02/07/2023]
Abstract
Astrocytes, which are homeostatic cells of the central nervous system (CNS), display remarkable heterogeneity in their morphology and function. Besides their physical and metabolic support to neurons, astrocytes modulate the blood-brain barrier, regulate CNS synaptogenesis, guide axon pathfinding, maintain brain homeostasis, affect neuronal development and plasticity, and contribute to diverse neuropathologies via secreted proteins. The identification of astrocytic proteome and secretome profiles has provided new insights into the maintenance of neuronal health and survival, the pathogenesis of brain injury, and neurodegeneration. Recent advances in proteomics research have provided an excellent catalog of astrocyte-secreted proteins. This review categorizes astrocyte-secreted proteins and discusses evidence that astrocytes play a crucial role in neuronal activity and brain function. An in-depth understanding of astrocyte-secreted proteins and their pathways is pivotal for the development of novel strategies for restoring brain homeostasis, limiting brain injury/inflammation, counteracting neurodegeneration, and obtaining functional recovery.
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Affiliation(s)
- Mithilesh Kumar Jha
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jong-Heon Kim
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Gyun Jee Song
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Won-Ha Lee
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea
| | - In-Kyu Lee
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Ho-Won Lee
- Department of Neurology, Brain Science and Engineering Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Seong Soo A An
- Department of BioNano Technology, Gachon University, Gyeonggi-do, Republic of Korea
| | - SangYun Kim
- Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Gyeonggi-do, Republic of Korea
| | - Kyoungho Suk
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea.
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18
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Frost GR, Li YM. The role of astrocytes in amyloid production and Alzheimer's disease. Open Biol 2017; 7:170228. [PMID: 29237809 PMCID: PMC5746550 DOI: 10.1098/rsob.170228] [Citation(s) in RCA: 235] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/16/2017] [Indexed: 12/18/2022] Open
Abstract
Alzheimer's disease (AD) is marked by the presence of extracellular amyloid beta (Aβ) plaques, intracellular neurofibrillary tangles (NFTs) and gliosis, activated glial cells, in the brain. It is thought that Aβ plaques trigger NFT formation, neuronal cell death, neuroinflammation and gliosis and, ultimately, cognitive impairment. There are increased numbers of reactive astrocytes in AD, which surround amyloid plaques and secrete proinflammatory factors and can phagocytize and break down Aβ. It was thought that neuronal cells were the major source of Aβ. However, mounting evidence suggests that astrocytes may play an additional role in AD by secreting significant quantities of Aβ and contributing to overall amyloid burden in the brain. Astrocytes are the most numerous cell type in the brain, and therefore even minor quantities of amyloid secretion from individual astrocytes could prove to be substantial when taken across the whole brain. Reactive astrocytes have increased levels of the three necessary components for Aβ production: amyloid precursor protein, β-secretase (BACE1) and γ-secretase. The identification of environmental factors, such as neuroinflammation, that promote astrocytic Aβ production, could redefine how we think about developing therapeutics for AD.
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Affiliation(s)
- Georgia R Frost
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Programs of Neurosciences, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
| | - Yue-Ming Li
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Programs of Neurosciences, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
- Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
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19
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Oksanen M, Petersen AJ, Naumenko N, Puttonen K, Lehtonen Š, Gubert Olivé M, Shakirzyanova A, Leskelä S, Sarajärvi T, Viitanen M, Rinne JO, Hiltunen M, Haapasalo A, Giniatullin R, Tavi P, Zhang SC, Kanninen KM, Hämäläinen RH, Koistinaho J. PSEN1 Mutant iPSC-Derived Model Reveals Severe Astrocyte Pathology in Alzheimer's Disease. Stem Cell Reports 2017; 9:1885-1897. [PMID: 29153989 PMCID: PMC5785689 DOI: 10.1016/j.stemcr.2017.10.016] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 10/19/2017] [Accepted: 10/19/2017] [Indexed: 01/08/2023] Open
Abstract
Alzheimer's disease (AD) is a common neurodegenerative disorder and the leading cause of cognitive impairment. Due to insufficient understanding of the disease mechanisms, there are no efficient therapies for AD. Most studies have focused on neuronal cells, but astrocytes have also been suggested to contribute to AD pathology. We describe here the generation of functional astrocytes from induced pluripotent stem cells (iPSCs) derived from AD patients with PSEN1 ΔE9 mutation, as well as healthy and gene-corrected isogenic controls. AD astrocytes manifest hallmarks of disease pathology, including increased β-amyloid production, altered cytokine release, and dysregulated Ca2+ homeostasis. Furthermore, due to altered metabolism, AD astrocytes show increased oxidative stress and reduced lactate secretion, as well as compromised neuronal supportive function, as evidenced by altering Ca2+ transients in healthy neurons. Our results reveal an important role for astrocytes in AD pathology and highlight the strength of iPSC-derived models for brain diseases. PSEN1 mutant AD astrocytes manifest hallmarks of AD pathology Altered mitochondrial metabolism in AD astrocytes increases oxidative stress AD astrocytes reduce the calcium signaling activity of healthy neurons Astrocytes are important in the pathogenesis of AD
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Affiliation(s)
- Minna Oksanen
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | | | - Nikolay Naumenko
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Katja Puttonen
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Šárka Lehtonen
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Max Gubert Olivé
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Anastasia Shakirzyanova
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Stina Leskelä
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Timo Sarajärvi
- Institute of Biomedicine, University of Eastern Finland, 70210 Kuopio, Finland
| | - Matti Viitanen
- Department of Geriatrics, University of Turku, Turku City Hospital, 20700 Turku, Finland; Department of Geriatrics, Karolinska Institutet and Karolinska University Hospital, Huddinge, 14186 Stockholm, Sweden
| | - Juha O Rinne
- Turku PET Centre, University of Turku, 20700 Turku, Finland; Division of Clinical Neurosciences, Turku University Hospital, 20700 Turku, Finland
| | - Mikko Hiltunen
- Institute of Biomedicine, University of Eastern Finland, 70210 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, 70210 Kuopio, Finland
| | - Annakaisa Haapasalo
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Rashid Giniatullin
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Pasi Tavi
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Su-Chun Zhang
- Waisman Center, University of Wisconsin, Madison, WI 53705, USA; Departments of Neuroscience and Neurology, University of Wisconsin, Madison, WI 53705, USA
| | - Katja M Kanninen
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Riikka H Hämäläinen
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Jari Koistinaho
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland.
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The Efficacy and Pharmacological Mechanism of Zn 7MT3 to Protect against Alzheimer's Disease. Sci Rep 2017; 7:13763. [PMID: 29061973 PMCID: PMC5653791 DOI: 10.1038/s41598-017-12800-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 09/15/2017] [Indexed: 11/13/2022] Open
Abstract
Alzheimer’s disease (AD) is one of the leading causes of death for people over 65 years. Worse still, no completely effective therapeutic agent is available so far. One important pathological hallmark of AD is accumulated amyloid-β (Aβ) plaques with dysregulated metal homeostasis. Human metallothionin 3 (MT3), a regulator of metal homeostasis, is downregulated at least 30% in AD brain. So far, some in vitro studies demonstrated its multiple functions related to AD. However, it is a great pity that systematic in vivo studies of MT3 on AD model animals are still a blank so far. In this study, we treated APP/PS1 mice with sustained drug release of Zn7MT3 directly to the central nervous system, and investigated the role and molecular mechanism of Zn7MT3 to protect against AD mice systematically. The results demonstrated that Zn7MT3 can significantly ameliorate cognitive deficits, regulate metal homeostasis, abolish Aβ plaque load, and reduce oxidative stress. Additionally, it has been confirmed that MT3 is penetrable to the blood brain barrier of AD mice. All these results support that Zn7MT3 is an effective AD suppressing agent and has potential for applications in Alzheimer’s disease therapy.
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Chiarini A, Armato U, Liu D, Dal Prà I. Calcium-Sensing Receptor Antagonist NPS 2143 Restores Amyloid Precursor Protein Physiological Non-Amyloidogenic Processing in Aβ-Exposed Adult Human Astrocytes. Sci Rep 2017; 7:1277. [PMID: 28455519 PMCID: PMC5430644 DOI: 10.1038/s41598-017-01215-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 03/27/2017] [Indexed: 12/11/2022] Open
Abstract
Physiological non-amyloidogenic processing (NAP) of amyloid precursor holoprotein (hAPP) by α-secretases (e.g., ADAM10) extracellularly sheds neurotrophic/neuroprotective soluble (s)APPα and precludes amyloid-β peptides (Aβs) production via β-secretase amyloidogenic processing (AP). Evidence exists that Aβs interact with calcium-sensing receptors (CaSRs) in human astrocytes and neurons, driving the overrelease of toxic Aβ42/Aβ42-os (oligomers), which is completely blocked by CaSR antagonist (calcilytic) NPS 2143. Here, we investigated the mechanisms underlying NPS 2143 beneficial effects in human astrocytes. Moreover, because Alzheimer's disease (AD) involves neuroinflammation, we examined whether NPS 2143 remained beneficial when both fibrillary (f)Aβ25-35 and a microglial cytokine mixture (CMT) were present. Thus, hAPP NAP prevailed over AP in untreated astrocytes, which extracellularly shed all synthesized sAPPα while secreting basal Aβ40/42 amounts. Conversely, fAβ25-35 alone dramatically reduced sAPPα extracellular shedding while driving Aβ42/Aβ42-os oversecretion that CMT accelerated but not increased, despite a concurring hAPP overexpression. NPS 2143 promoted hAPP and ADAM10 translocation to the plasma membrane, thereby restoring sAPPα extracellular shedding and fully suppressing any Aβ42/Aβ42-os oversecretion, but left hAPP expression unaffected. Therefore, as anti-AD therapeutics calcilytics support neuronal viability by safeguarding astrocytes neurotrophic/neuroprotective sAPPα shedding, suppressing neurons and astrocytes Aβ42/Aβ42-os build-up/secretion, and remaining effective even under AD-typical neuroinflammatory conditions.
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Affiliation(s)
- Anna Chiarini
- Human Histology & Embryology Unit, Medical School, University of Verona, Verona, Venetia, Italy.
| | - Ubaldo Armato
- Human Histology & Embryology Unit, Medical School, University of Verona, Verona, Venetia, Italy
| | - Daisong Liu
- The Third Xiangya Hospital of Central South University, Department of Plastic Surgery, Changsha, Hunan, China
| | - Ilaria Dal Prà
- Human Histology & Embryology Unit, Medical School, University of Verona, Verona, Venetia, Italy.
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22
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Sabbah DA, Zhong HA. Modeling the protonation states of β-secretase binding pocket by molecular dynamics simulations and docking studies. J Mol Graph Model 2016; 68:206-215. [DOI: 10.1016/j.jmgm.2016.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 07/06/2016] [Accepted: 07/17/2016] [Indexed: 01/12/2023]
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Abstract
UNLABELLED Secreted factors play a central role in normal and pathological processes in every tissue in the body. The brain is composed of a highly complex milieu of different cell types and few methods exist that can identify which individual cells in a complex mixture are secreting specific analytes. By identifying which cells are responsible, we can better understand neural physiology and pathophysiology, more readily identify the underlying pathways responsible for analyte production, and ultimately use this information to guide the development of novel therapeutic strategies that target the cell types of relevance. We present here a method for detecting analytes secreted from single human induced pluripotent stem cell (iPSC)-derived neural cells and have applied the method to measure amyloid β (Aβ) and soluble amyloid precursor protein-alpha (sAPPα), analytes central to Alzheimer's disease pathogenesis. Through these studies, we have uncovered the dynamic range of secretion profiles of these analytes from single iPSC-derived neuronal and glial cells and have molecularly characterized subpopulations of these cells through immunostaining and gene expression analyses. In examining Aβ and sAPPα secretion from single cells, we were able to identify previously unappreciated complexities in the biology of APP cleavage that could not otherwise have been found by studying averaged responses over pools of cells. This technique can be readily adapted to the detection of other analytes secreted by neural cells, which would have the potential to open new perspectives into human CNS development and dysfunction. SIGNIFICANCE STATEMENT We have established a technology that, for the first time, detects secreted analytes from single human neurons and astrocytes. We examine secretion of the Alzheimer's disease-relevant factors amyloid β (Aβ) and soluble amyloid precursor protein-alpha (sAPPα) and present novel findings that could not have been observed without a single-cell analytical platform. First, we identify a previously unappreciated subpopulation that secretes high levels of Aβ in the absence of detectable sAPPα. Further, we show that multiple cell types secrete high levels of Aβ and sAPPα, but cells expressing GABAergic neuronal markers are overrepresented. Finally, we show that astrocytes are competent to secrete high levels of Aβ and therefore may be a significant contributor to Aβ accumulation in the brain.
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Fisher JR, Wallace CE, Tripoli DL, Sheline YI, Cirrito JR. Redundant Gs-coupled serotonin receptors regulate amyloid-β metabolism in vivo. Mol Neurodegener 2016; 11:45. [PMID: 27315796 PMCID: PMC4912779 DOI: 10.1186/s13024-016-0112-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 06/14/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The aggregation of amyloid-β (Aβ) into insoluble plaques is a hallmark pathology of Alzheimer's disease (AD). Previous work has shown increasing serotonin levels with selective serotonin re-uptake inhibitor (SSRI) compounds reduces Aβ in the brain interstitial fluid (ISF) in a mouse model of AD and in the cerebrospinal fluid of humans. We investigated which serotonin receptor (5-HTR) subtypes and downstream effectors were responsible for this reduction. RESULTS Agonists of 5-HT4R, 5-HT6R, and 5-HT7R significantly reduced ISF Aβ, but agonists of other receptor subtypes did not. Additionally, inhibition of Protein Kinase A (PKA) blocked the effects of citalopram, an SSRI, on ISF Aβ levels. Serotonin signaling does not appear to change gene expression to reduce Aβ levels in acute timeframes, but likely acts within the cytoplasm to increase α-secretase enzymatic activity. Broad pharmacological inhibition of putative α-secretases increased ISF Aβ and blocked the effects of citalopram. CONCLUSIONS In total, these studies map the major signaling components linking serotonin receptors to suppression of brain ISF Aβ. These results suggest the reduction in ISF Aβ is mediated by a select group of 5-HTRs and open future avenues for targeted therapy of AD.
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Affiliation(s)
- Jonathan R Fisher
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Clare E Wallace
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Danielle L Tripoli
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Yvette I Sheline
- Departments of Psychiatry, Radiology, and Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - John R Cirrito
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA. .,Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA. .,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA. .,Present Address: Washington University, Neurology, 660 South Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA.
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Astrogliosis: An integral player in the pathogenesis of Alzheimer's disease. Prog Neurobiol 2016; 144:121-41. [PMID: 26797041 DOI: 10.1016/j.pneurobio.2016.01.001] [Citation(s) in RCA: 186] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 11/10/2015] [Accepted: 01/10/2016] [Indexed: 12/15/2022]
Abstract
Alzheimer's disease is the main cause of dementia in the elderly and begins with a subtle decline in episodic memory followed by a more general decline in overall cognitive abilities. Though the exact trigger for this cascade of events remains unknown the presence of the misfolded amyloid-beta protein triggers reactive gliosis, a prominent neuropathological feature in the brains of Alzheimer's patients. The cytoskeletal and morphological changes of astrogliosis are its evident features, while changes in oxidative stress defense, cholesterol metabolism, and gene transcription programs are less manifest. However, these latter molecular changes may underlie a disruption in homeostatic regulation that keeps the brain environment balanced. Astrocytes in Alzheimer's disease show changes in glutamate and GABA signaling and recycling, potassium buffering, and in cholinergic, purinergic, and calcium signaling. Ultimately the dysregulation of homeostasis maintained by astrocytes can have grave consequences for the stability of microcircuits within key brain regions. Specifically, altered inhibition influenced by astrocytes can lead to local circuit imbalance with farther reaching consequences for the functioning of larger neuronal networks. Healthy astrocytes have a role in maintaining and modulating normal neuronal communication, synaptic physiology and energy metabolism, astrogliosis interferes with these functions. This review considers the molecular and functional changes occurring during astrogliosis in Alzheimer's disease, and proposes that astrocytes are key players in the development of dementia.
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Lee SJ, Seo BR, Koh JY. Metallothionein-3 modulates the amyloid β endocytosis of astrocytes through its effects on actin polymerization. Mol Brain 2015; 8:84. [PMID: 26637294 PMCID: PMC4670512 DOI: 10.1186/s13041-015-0173-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 11/30/2015] [Indexed: 12/30/2022] Open
Abstract
Background Astrocytes may play important roles in the pathogenesis of Alzheimer’s disease (AD) by clearing extracellular amyloid beta (Aβ) through endocytosis and degradation. We recently showed that metallothionein 3 (Mt3), a zinc-binding metallothionein that is enriched in the central nervous system, contributes to actin polymerization in astrocytes. Because actin is likely involved in the endocytosis of Aβ, we investigated the possible role of Mt3 in Aβ endocytosis by cortical astrocytes in this study. Results To assess the route of Aβ uptake, we exposed cultured astrocytes to fluorescently labeled Aβ1–40 or Aβ1–42 together with chloropromazine (CP) or methyl-beta-cyclodextrin (MβCD), inhibitors of clathrin- and caveolin-dependent endocytosis, respectively. CP treatment almost completely blocked Aβ1–40 and Aβ1–42 endocytosis, whereas exposure to MβCD had no significant effect. Actin disruption with cytochalasin D (CytD) or latrunculin B also completely blocked Aβ1–40 and Aβ1–42 endocytosis. Because the absence of Mt3 also results in actin disruption, we examined Aβ1–40 and Aβ1–42 uptake and expression in Mt3−/− astrocytes. Compared with wild-type (WT) cells, Mt3−/− cells exhibited markedly reduced Aβ1–40 and Aβ1–42 endocytosis and expression of Aβ1-42 monomers and oligomers. A similar reduction was observed in CytD-treated WT cells. Finally, actin disruption and Mt3 knockout each increased the overall levels of clathrin and the associated protein phosphatidylinositol-binding clathrin assembly protein (PICALM) in astrocytes. Conclusions Our results suggest that the absence of Mt3 reduces Aβ uptake in astrocytes through an abnormality in actin polymerization. In light of evidence that Mt3 is downregulated in AD, our findings indicate that this mechanism may contribute to the extracellular accumulation of Aβ in this disease.
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Affiliation(s)
- Sook-Jeong Lee
- Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, South Korea. .,Present address: Department of New Drug Discovery and Development, Chungnam National University, 99 Daehak-ro, Yuseong, Daejeon, 34134, South Korea.
| | - Bo-Ra Seo
- Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, South Korea.
| | - Jae-Young Koh
- Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, South Korea. .,Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-Gil, Songpa-Gu, Seoul, 05505, South Korea.
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MacLeod R, Hillert EK, Cameron RT, Baillie GS. The role and therapeutic targeting of α-, β- and γ-secretase in Alzheimer's disease. Future Sci OA 2015; 1:FSO11. [PMID: 28031886 PMCID: PMC5137966 DOI: 10.4155/fso.15.9] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia in the elderly and its prevalence is set to increase rapidly in coming decades. However, there are as yet no available drugs that can halt or even stabilize disease progression. One of the main pathological features of AD is the presence in the brain of senile plaques mainly composed of aggregated β amyloid (Aβ), a derivative of the longer amyloid precursor protein (APP). The amyloid hypothesis proposes that the accumulation of Aβ within neural tissue is the initial event that triggers the disease. Here we review research efforts that have attempted to inhibit the generation of the Aβ peptide through modulation of the activity of the proteolytic secretases that act on APP and discuss whether this is a viable therapeutic strategy for treating AD.
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Affiliation(s)
- Ruth MacLeod
- Institute of Cardiovascular & Medical Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Ellin-Kristina Hillert
- Institute of Cardiovascular & Medical Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Ryan T Cameron
- Institute of Cardiovascular & Medical Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - George S Baillie
- Institute of Cardiovascular & Medical Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Kandalepas PC, Vassar R. The normal and pathologic roles of the Alzheimer's β-secretase, BACE1. Curr Alzheimer Res 2015; 11:441-9. [PMID: 24893886 DOI: 10.2174/1567205011666140604122059] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 01/15/2014] [Accepted: 01/25/2014] [Indexed: 01/18/2023]
Abstract
As the most common neurodegenerative disease, therapeutic avenues for the treatment and prevention of Alzheimer's Disease are highly sought after. The aspartic protease BACE1 is the initiator enzyme for the formation of Aβ, a major constituent of amyloid plaques that represent one of the hallmark pathological features of this disorder. Thus, targeting BACE1 for disease-modifying AD therapies represents a rationale approach. The collective knowledge acquired from investigations of BACE1 deletion mutants and characterization of BACE1 substrates has downstream significance not only for the discovery of AD drug therapies but also for predicting side effects of BACE1 inhibition. Here we discuss the identification and validation of BACE1 as the β-secretase implicated in AD, in addition to information regarding BACE1 cell biology, localization, substrates and potential physiological functions derived from BACE1 knockout models.
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Affiliation(s)
| | - Robert Vassar
- Northwestern University, Feinberg School of Medicine, Department of Cell & Molecular Biology, 300 E. Superior, Tarry 8-713, IL 60611, Chicago.
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29
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Avila-Muñoz E, Arias C. When astrocytes become harmful: functional and inflammatory responses that contribute to Alzheimer's disease. Ageing Res Rev 2014; 18:29-40. [PMID: 25078115 DOI: 10.1016/j.arr.2014.07.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/03/2014] [Accepted: 07/21/2014] [Indexed: 12/24/2022]
Abstract
A growing body of research suggests that astrocytes play roles as contributors to the pathophysiology of Alzheimer's disease (AD). Several lines of evidence propose that activated astrocytes produce and release proinflammatory molecules that may be critical for the generation of amyloid-β peptide (Aβ). However, accumulating evidence indicates that Aβ may activate astrocytes, which leads to an increase in cytokines that has been suggested to be a causative factor in the cognitive dysfunction of AD; thus, a vicious circle may be created. Intrinsic inflammatory mechanisms may provide a regulatory system that is capable of influencing the neuronal microenvironment that affects neuronal survival. In this article, we address the evidence surrounding the interactions of dysfunctional astrocytes with neighboring neurons that may initiate a cascade of events that culminates with neuronal injury and the expression of the hallmark lesions of AD. Comprehensive knowledge of the molecular mechanisms underlying the participation of astrocytes in neurodegeneration could aid the development of therapies to restore proper astrocyte function that can be used in AD patients to prevent or alleviate the progression of the disease in a more efficient and comprehensive manner.
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30
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Wang Q, Xu Z, Tang J, Sun J, Gao J, Wu T, Xiao M. Voluntary exercise counteracts Aβ25-35-induced memory impairment in mice. Behav Brain Res 2013; 256:618-25. [DOI: 10.1016/j.bbr.2013.09.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/06/2013] [Accepted: 09/10/2013] [Indexed: 11/26/2022]
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31
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Nomura S, Umeda T, Tomiyama T, Mori H. The E693Δ (Osaka) mutation in amyloid precursor protein potentiates cholesterol-mediated intracellular amyloid β toxicity via its impaired cholesterol efflux. J Neurosci Res 2013; 91:1541-50. [DOI: 10.1002/jnr.23278] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 06/21/2013] [Accepted: 06/21/2013] [Indexed: 12/21/2022]
Affiliation(s)
- Sachiko Nomura
- Department of Neuroscience; Osaka City University Graduate School of Medicine; Osaka Japan
- Core Research for Evolutional Science and Technology; Japan Science and Technology Agency; Tokyo Japan
| | - Tomohiro Umeda
- Department of Neuroscience; Osaka City University Graduate School of Medicine; Osaka Japan
- Core Research for Evolutional Science and Technology; Japan Science and Technology Agency; Tokyo Japan
| | - Takami Tomiyama
- Department of Neuroscience; Osaka City University Graduate School of Medicine; Osaka Japan
- Core Research for Evolutional Science and Technology; Japan Science and Technology Agency; Tokyo Japan
| | - Hiroshi Mori
- Department of Neuroscience; Osaka City University Graduate School of Medicine; Osaka Japan
- Core Research for Evolutional Science and Technology; Japan Science and Technology Agency; Tokyo Japan
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Brambilla L, Martorana F, Rossi D. Astrocyte signaling and neurodegeneration: new insights into CNS disorders. Prion 2012; 7:28-36. [PMID: 23093800 DOI: 10.4161/pri.22512] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Growing evidence indicates that astrocytes cannot be just considered as passive supportive cells deputed to preserve neuronal activity and survival, but rather they are involved in a striking number of active functions that are critical to the performance of the central nervous system (CNS). As a consequence, it is becoming more and more evident that the peculiar properties of these cells can actively contribute to the extraordinary functional complexity of the brain and spinal cord. This new perception of the functioning of the CNS opens up a wide range of new possibilities to interpret various physiological and pathological events, and moves the focus beyond the neuronal compartment toward astrocyte-neuron interactions. With this in mind, here we provide a synopsis of the activities astrocytes perform in normal conditions, and we try to discuss what goes wrong with these cells in specific pathological conditions, such as Alzheimer Disease, prion diseases and amyotrophic lateral sclerosis.
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Affiliation(s)
- Liliana Brambilla
- Laboratory for Research on Neurodegenerative Disorders, IRCCS Fondazione Salvatore Maugeri, Pavia, Italy
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Sathya M, Premkumar P, Karthick C, Moorthi P, Jayachandran KS, Anusuyadevi M. BACE1 in Alzheimer's disease. Clin Chim Acta 2012; 414:171-8. [PMID: 22926063 DOI: 10.1016/j.cca.2012.08.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/08/2012] [Accepted: 08/15/2012] [Indexed: 12/18/2022]
Abstract
Targeting BACE1 (β-site APP cleaving enzyme 1 or β-secretase) is the focus of Alzheimer's disease (AD) research because this aspartyl protease is involved in the abnormal production of β amyloid plaques (Aβ), the hallmark of its pathophysiology. Evidence suggests that there is a strong connection between AD and BACE1. As such, strategies to inhibit Aβ formation in the brain should prove beneficial for AD treatment. Aβ, the product of the large type1 trans-membrane protein amyloid precursor protein (APP), is produced in a two-step proteolytic process initiated by BACE1 (β-secretase) and followed by γ-secretase. Due to its apparent rate limiting function, BACE1 appears to be a prime target to prevent Aβ generation in AD. Following its discovery, the BACE1 has been cloned, its structure solved, novel physiologic substrates discovered and numerous inhibitors developed. This review focuses on elucidating the role of BACE1 to facilitate drug development in the treatment of AD.
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Affiliation(s)
- M Sathya
- Department of Biochemistry, Bharathidasan University, Trichy 24, India
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Grolla AA, Fakhfouri G, Balzaretti G, Marcello E, Gardoni F, Canonico PL, DiLuca M, Genazzani AA, Lim D. Aβ leads to Ca²⁺ signaling alterations and transcriptional changes in glial cells. Neurobiol Aging 2012; 34:511-22. [PMID: 22673114 DOI: 10.1016/j.neurobiolaging.2012.05.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 05/03/2012] [Accepted: 05/09/2012] [Indexed: 01/26/2023]
Abstract
The pathogenesis of Alzheimer's disease includes accumulation of toxic amyloid beta (Aβ) peptides. A recently developed cell-permeable peptide, termed Tat-Pro, disrupts the complex between synapse-associated protein 97 (SAP97) and the α-secretase a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), thereby leading to an alteration of the trafficking of the enzyme, which is important for nonamyloidogenic processing of amyloid precursor protein (APP). We report that Tat-Pro treatment, as well as the treatment with exogenous Aβ, deregulates Ca(2+) homeostasis specifically in astrocytes through increased expression of key components of Ca(2+) signaling, metabotropic glutamate receptor-5 and inositol 1,4,5-trisphosphate receptor-1. This is accompanied by potentiation of (S)-3,5-dihydroxyphenylglycine-induced Ca(2+) transients. Calcineurin inhibition reverts all these effects. Furthermore, our data demonstrate that astrocytes express all the components for the amyloidogenic and nonamyloidogenic processing of APP including APP itself, beta-site APP-cleaving enzyme 1 (BACE1), ADAM10, γ-secretase, and SAP97. Indeed, treatment with Tat-Pro for 48 hours significantly increased the amount of Aβ(1-42) in the medium of cultured astrocytes. Taken together, our results suggest that astroglia might be active players in Aβ production and indicate that the calcium hypothesis of Alzheimer's disease may recognize glial cells as important intermediates.
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Affiliation(s)
- Ambra A Grolla
- DiSCAFF, Università degli Studi del Piemonte Orientale Amedeo Avogadro, Novara, Italy
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Abstract
β-Site APP-cleaving enzyme (BACE1) cleaves the amyloid precursor protein (APP) at the β-secretase site to initiate the production of Aβ peptides. These accumulate to form toxic oligomers and the amyloid plaques associated with Alzheimer's disease (AD). An increase of BACE1 levels in the brain of AD patients has been mostly attributed to alterations of its intracellular trafficking. Golgi-associated adaptor proteins, GGA sort BACE1 for export to the endosomal compartment, which is the major cellular site of BACE1 activity. BACE1 undergoes recycling between endosome, trans-Golgi network (TGN), and the plasma membrane, from where it is endocytosed and either further recycled or retrieved to the endosome. Phosphorylation of Ser498 facilitates BACE1 recognition by GGA1 for retrieval to the endosome. Ubiquitination of BACE1 C-terminal Lys501 signals GGA3 for exporting BACE1 to the lysosome for degradation. In addition, the retromer mediates the retrograde transport of BACE1 from endosome to TGN. Decreased levels of GGA proteins and increased levels of retromer-associated sortilin have been associated with AD. Both would promote the co-localization of BACE1 and the amyloid precursor protein in the TGN and endosomes. Decreased levels of GGA3 also impair BACE1 degradation. Further understanding of BACE1 trafficking and its regulation may offer new therapeutic approaches for the treatment of Alzheimer's disease.
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Affiliation(s)
- Jiangli Tan
- Department of Pathology, and Mental Health Research Institute, The University of Melbourne, Parkville, Australia
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Abstract
Our knowledge of the etiology of Alzheimer's disease (AD) has advanced tremendously since the discovery of amyloid beta (Aβ) aggregation in diseased brains. Accumulating evidence suggests that Aβ plays a causative role in AD. The β-secretase enzyme, beta-site APP cleaving enzyme-1 (BACE1), is also implicated in AD pathogenesis, given that BACE1 cleavage of amyloid precursor protein is the initiating step in the formation of Aβ. As a result, BACE1 inhibition has been branded as a potential AD therapy. In this study, we review the identification and basic characteristics of BACE1, as well as the progress in our understanding of BACE1 cell biology, substrates, and phenotypes of BACE1 knockout mice that are informative about the physiological functions of BACE1 beyond amyloid precursor protein cleavage. These data are crucial for predicting potential mechanism-based toxicity that would arise from inhibiting BACE1 for the treatment or prevention of AD.
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Affiliation(s)
- Patty C Kandalepas
- Northwestern University, Feinberg School of Medicine, Department of Cell and Molecular Biology, Chicago, Illinois, USA
| | - Robert Vassar
- Northwestern University, Feinberg School of Medicine, Department of Cell and Molecular Biology, Chicago, Illinois, USA
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37
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Zhao J, O'Connor T, Vassar R. The contribution of activated astrocytes to Aβ production: implications for Alzheimer's disease pathogenesis. J Neuroinflammation 2011; 8:150. [PMID: 22047170 PMCID: PMC3216000 DOI: 10.1186/1742-2094-8-150] [Citation(s) in RCA: 262] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 11/02/2011] [Indexed: 01/01/2023] Open
Abstract
Background β-Amyloid (Aβ) plays a central role in Alzheimer's disease (AD) pathogenesis. Neurons are major sources of Aβ in the brain. However, astrocytes outnumber neurons by at least five-fold. Thus, even a small level of astrocytic Aβ production could make a significant contribution to Aβ burden in AD. Moreover, activated astrocytes may increase Aβ generation. β-Site APP cleaving enzyme 1 (BACE1) cleavage of amyloid precursor protein (APP) initiates Aβ production. Here, we explored whether pro-inflammatory cytokines or Aβ42 would increase astrocytic levels of BACE1, APP, and β-secretase processing, implying a feed-forward mechanism of astrocytic Aβ production. Methods Mouse primary astrocytes were treated with combinations of LPS, TNF-α, IFN-γ, and IL-1β and analyzed by immunoblot and ELISA for endogenous BACE1, APP, and secreted Aβ40 levels. Inhibition of JAK and iNOS signaling in TNF-α+IFN-γ-stimulated astrocytes was also analyzed. In addition, C57BL/6J or Tg2576 mouse astrocytes were treated with oligomeric or fibrillar Aβ42 and analyzed by immunoblot for levels of BACE1, APP, and APPsβsw. Astrocytic BACE1 and APP mRNA levels were measured by TaqMan RT-PCR. Results TNF-α+IFN-γ stimulation significantly increased levels of astrocytic BACE1, APP, and secreted Aβ40. BACE1 and APP elevations were post-transcriptional at early time-points, but became transcriptional with longer TNF-α+IFN-γ treatment. Despite a ~4-fold increase in astrocytic BACE1 protein level following TNF-α+IFN-γ stimulation, BACE1 mRNA level was significantly decreased suggesting a post-transcriptional mechanism. Inhibition of iNOS and JAK did not reduce TNF-α+IFN-γ-stimulated elevation of astrocytic BACE1, APP, and Aβ40, except that JAK inhibition blocked the APP increase. Finally, oligomeric and fibrillar Aβ42 dramatically increased levels of astrocytic BACE1, APP, and APPsβsw through transcriptional mechanisms, at least in part. Conclusions Cytokines including TNF-α+IFN-γ increase levels of endogenous BACE1, APP, and Aβ and stimulate amyloidogenic APP processing in astrocytes. Oligomeric and fibrillar Aβ42 also increase levels of astrocytic BACE1, APP, and β-secretase processing. Together, our results suggest a cytokine- and Aβ42-driven feed-forward mechanism that promotes astrocytic Aβ production. Given that astrocytes greatly outnumber neurons, activated astrocytes may represent significant sources of Aβ during neuroinflammation in AD.
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Affiliation(s)
- Jie Zhao
- Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
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38
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Lasagna-Reeves CA, Kayed R. Astrocytes contain amyloid-β annular protofibrils in Alzheimer's disease brains. FEBS Lett 2011; 585:3052-7. [PMID: 21872592 DOI: 10.1016/j.febslet.2011.08.027] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 08/17/2011] [Accepted: 08/18/2011] [Indexed: 10/17/2022]
Abstract
Annular protofibrils (APFs) represent a newly described and distinct class of amyloid structures formed by disease-associated proteins. In vitro, these pore-like structures have been implicated in membrane permeabilization and ion homeostasis via pore formation. Still, their formation and relevance in vivo are poorly understood. Herein, we report that APFs are in human Alzheimer's disease brain samples and that amyloid-β APFs were associated with activated astrocytes. Moreover, we show that amyloid-β APFs in astrocytes adopt a conformation in which the N-terminal region is buried inside the wall of the pore. Our results together with previous studies suggest that the formation of amyloid-β APFs in astrocytes could be a relevant event in the pathogenesis of Alzheimer's disease and validate this amyloidogenic structure as a target for the prevention of the disease.
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Affiliation(s)
- Cristian A Lasagna-Reeves
- George P. and Cynthia Woods Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555-1045, USA.
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Cole SL, Vassar R. The Basic Biology of BACE1: A Key Therapeutic Target for Alzheimer's Disease. Curr Genomics 2011; 8:509-30. [PMID: 19415126 PMCID: PMC2647160 DOI: 10.2174/138920207783769512] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 12/27/2007] [Accepted: 12/27/2007] [Indexed: 11/22/2022] Open
Abstract
Alzheimer’s disease (AD) is an intractable, neurodegenerative disease that appears to be brought about by both genetic and non-genetic factors. The neuropathology associated with AD is complex, although amyloid plaques composed of the β-amyloid peptide (Aβ) are hallmark neuropathological lesions of AD brain. Indeed, Aβ plays an early and central role in this disease. β-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is the initiating enzyme in Aβ genesis and BACE1 levels are elevated under a variety of conditions. Given the strong correlation between Aβ and AD, and the elevation of BACE1 in this disease, this enzyme is a prime drug target for inhibiting Aβ production in AD. However, nine years on from the initial identification of BACE1, and despite intense research, a number of key questions regarding BACE1 remain unanswered. Indeed, drug discovery and development for AD continues to be challenging. While current AD therapies temporarily slow cognitive decline, treatments that address the underlying pathologic mechanisms of AD are completely lacking. Here we review the basic biology of BACE1. We pay special attention to recent research that has provided some answers to questions such as those involving the identification of novel BACE1 substrates, the potential causes of BACE1 elevation and the putative function of BACE1 in health and disease. Our increasing understanding of BACE1 biology should aid the development of compounds that interfere with BACE1 expression and activity and may lead to the generation of novel therapeutics for AD.
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Affiliation(s)
- S L Cole
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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40
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Mohamed A, Posse de Chaves E. Aβ internalization by neurons and glia. Int J Alzheimers Dis 2011; 2011:127984. [PMID: 21350608 PMCID: PMC3042623 DOI: 10.4061/2011/127984] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Accepted: 12/23/2010] [Indexed: 11/20/2022] Open
Abstract
In the brain, the amyloid β peptide (Aβ) exists extracellularly and inside neurons. The intracellular accumulation of Aβ in Alzheimer's disease brain has been questioned for a long time. However, there is now sufficient strong evidence indicating that accumulation of Aβ inside neurons plays an important role in the pathogenesis of Alzheimer's disease. Intraneuronal Aβ originates from intracellular cleavage of APP and from Aβ internalization from the extracellular milieu. We discuss here the different molecular mechanisms that are responsible for Aβ internalization in neurons and the links between Aβ internalization and neuronal dysfunction and death. A brief description of Aβ uptake by glia is also presented.
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Affiliation(s)
- Amany Mohamed
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada T6G 2H7
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Cole SL, Vassar R. The role of amyloid precursor protein processing by BACE1, the beta-secretase, in Alzheimer disease pathophysiology. J Biol Chem 2008; 283:29621-5. [PMID: 18650431 DOI: 10.1074/jbc.r800015200] [Citation(s) in RCA: 180] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Amyloid plaques, composed of the amyloid beta-protein (Abeta), are hallmark neuropathological lesions in Alzheimer disease (AD) brain. Abeta fulfills a central role in AD pathogenesis, and reduction of Abeta levels should prove beneficial for AD treatment. Abeta generation is initiated by proteolysis of amyloid precursor protein (APP) by the beta-secretase enzyme BACE1. Bace1 knockout (Bace1(-/-)) mice have validated BACE1 as the authentic beta-secretase in vivo. BACE1 is essential for Abeta generation and represents a suitable drug target for AD therapy, especially because this enzyme is up-regulated in AD. However, although initial data indicated that Bace1(-/-) mice lack an overt phenotype, the BACE1-mediated processing of APP and other substrates may be important for specific biological processes. In this minireview, topics range from the initial identification of BACE1 to the fundamental knowledge gaps that remain in our understanding of this protease. We address pertinent questions such as putative causes of BACE1 elevation in AD and discuss why, nine years since the identification of BACE1, treatments that address the underlying pathological mechanisms of AD are still lacking.
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Affiliation(s)
- Sarah L Cole
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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Satoh J, Kuroda Y. Amyloid precursor protein β‐secretase (BACE) mRNA expression in human neural cell lines following induction of neuronal differentiation and exposure to cytokines and growth factors. Neuropathology 2008. [DOI: 10.1111/j.1440-1789.2000.00349.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jun‐ichi Satoh
- Division of Neurology, Department of Internal Medicine, Saga Medical School, Saga, Japan
| | - Yasuo Kuroda
- Division of Neurology, Department of Internal Medicine, Saga Medical School, Saga, Japan
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Cole SL, Vassar R. The Alzheimer's disease beta-secretase enzyme, BACE1. Mol Neurodegener 2007; 2:22. [PMID: 18005427 PMCID: PMC2211305 DOI: 10.1186/1750-1326-2-22] [Citation(s) in RCA: 336] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 11/15/2007] [Indexed: 12/11/2022] Open
Abstract
The pathogenesis of Alzheimer's disease is highly complex. While several pathologies characterize this disease, amyloid plaques, composed of the β-amyloid peptide are hallmark neuropathological lesions in Alzheimer's disease brain. Indeed, a wealth of evidence suggests that β-amyloid is central to the pathophysiology of AD and is likely to play an early role in this intractable neurodegenerative disorder. The BACE1 enzyme is essential for the generation of β-amyloid. BACE1 knockout mice do not produce β-amyloid and are free from Alzheimer's associated pathologies including neuronal loss and certain memory deficits. The fact that BACE1 initiates the formation of β-amyloid, and the observation that BACE1 levels are elevated in this disease provide direct and compelling reasons to develop therapies directed at BACE1 inhibition thus reducing β-amyloid and its associated toxicities. However, new data indicates that complete abolishment of BACE1 may be associated with specific behavioral and physiological alterations. Recently a number of non-APP BACE1 substrates have been identified. It is plausible that failure to process certain BACE1 substrates may underlie some of the reported abnormalities in the BACE1-deficient mice. Here we review BACE1 biology, covering aspects ranging from the initial identification and characterization of this enzyme to recent data detailing the apparent dysregulation of BACE1 in Alzheimer's disease. We pay special attention to the putative function of BACE1 during healthy conditions and discuss in detail the relationship that exists between key risk factors for AD, such as vascular disease (and downstream cellular consequences), and the pathogenic alterations in BACE1 that are observed in the diseased state.
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Affiliation(s)
- Sarah L Cole
- Department of Cell and Molecular Biology, The Feinberg School of Medicine, Northwestern University, Chicago Avenue, Chicago, IL, USA.
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Je JY, Kim SK. Water-soluble chitosan derivatives as a BACE1 inhibitor. Bioorg Med Chem 2005; 13:6551-5. [PMID: 16084727 DOI: 10.1016/j.bmc.2005.07.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Revised: 07/11/2005] [Accepted: 07/12/2005] [Indexed: 11/21/2022]
Abstract
BACE1 (the beta-site APP-cleaving enzyme) inhibitory activities of water-soluble chitosan derivatives substituted with aminoethyl, dimethylaminoethyl and diethylaminoethyl groups were investigated. AE-chitosan (90%) prepared from 90% deacetylated chitosan showed the strongest BACE1 inhibitory activity than those of other derivatives. The inhibitory pattern was found to be non-competitive by Dixon plot, and the value of the inhibition constant (K(i)) was 85 microg/mL.
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Affiliation(s)
- Jae-Young Je
- Department of Chemistry, Pukyong National University, Busan, Republic of Korea
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Harada H, Tamaoka A, Ishii K, Shoji S, Kametaka S, Kametani F, Saito Y, Murayama S. Beta-site APP cleaving enzyme 1 (BACE1) is increased in remaining neurons in Alzheimer's disease brains. Neurosci Res 2005; 54:24-9. [PMID: 16290302 DOI: 10.1016/j.neures.2005.10.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 09/07/2005] [Accepted: 10/11/2005] [Indexed: 11/26/2022]
Abstract
Alzheimer's disease (AD) is characterized by the extensive deposition of amyloid beta protein (Abeta) in the brain cortex. Abeta is produced from beta-amyloid precursor protein (APP) by beta-secretase and gamma-secretase. beta-Secretase has been identified as beta-site APP cleaving enzyme1 (BACE1). We produced rabbit polyclonal antibodies against the amino and the carboxyl terminals of BACE1. Using these antibodies, BACE1 was characterized in temporal lobe cortices by Western blotting and immunohistochemistry. Immunohistochemical studies employing anti-GFAP and anti-MAP2 antibodies as well as anti-BACE1 antibodies showed that BACE1 was expressed exclusively in neurons but not in glial cells. Brain samples were directly extracted by 0.5% SDS and analyzed by Western blotting and densitometer. Although the mean level of BACE1/mg protein in AD brains was not increased, the ratio of BACE1 to MAP2 or to NSE was significantly increased compared with that in control brains. Taken together, these findings suggest that those neurons that survive in AD brains might generate more BACE1 than normal neurons in control brains, indicating that increased BACE1 activity could be one of the causes of AD. This could justify the development of anti-BACE1 drugs for AD treatment.
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Affiliation(s)
- Hirotsugu Harada
- Department of Neurology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
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Byun HG, Kim YT, Park PJ, Lin X, Kim SK. Chitooligosaccharides as a novel β-secretase inhibitor. Carbohydr Polym 2005. [DOI: 10.1016/j.carbpol.2005.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Engelberg H. Pathogenic factors in vascular dementia and Alzheimer's disease. Multiple actions of heparin that probably are beneficial. Dement Geriatr Cogn Disord 2005; 18:278-98. [PMID: 15286460 DOI: 10.1159/000080034] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/04/2004] [Indexed: 12/22/2022] Open
Abstract
The following areas are discussed in this review: atherogenesis; cerebrovascular factors; hypoperfusion; beta-amyloid production; beta-amyloid fibril formation; beta-sheets; metal cations; reactive oxygen species/free radicals; chronic inflammatory factors; endogenous plasma heparin; lipoprotein lipase; polyamines; protein kinase C; casein kinases; phospholipase A2; serine proteases; myeloperoxidase; cyclooxygenase 2; cysteine proteases; caspases; proprotein convertases; aspartic proteases; cyclin proteinases; thrombin; tau hyperphosphorylation; advanced glycosylation end products; activator protein 1; calcium; apolipoprotein E epsilon4; histamine; blood-brain barrier; glutamate; transglutaminase; insulin-like growth factor 1.
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Vassar R. BACE1: the beta-secretase enzyme in Alzheimer's disease. J Mol Neurosci 2004; 23:105-14. [PMID: 15126696 DOI: 10.1385/jmn:23:1-2:105] [Citation(s) in RCA: 257] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2002] [Accepted: 03/18/2003] [Indexed: 11/11/2022]
Abstract
Data that have accumulated for well over a decade have implicated the beta-amyloid (Abeta) peptide as a central player in the pathogenesis of Alzheimer's disease (AD). Amyloid plaques, composed primarily of Abeta progressively form in the brains of AD patients, and mutations in three genes (amyloid precursor protein [APP] and presenilin 1 and 2 [PS1 and PS2]) cause early-onset familial AD (FAD) by directly increasing production of the toxic, plaque-promoting Abeta42 peptide. Given the strong association between Abeta and AD, it is likely that therapeutic strategies to lower the levels of Abeta in the brain should prove beneficial for the treatment of AD. One such strategy could involve inhibiting the enzymes that generate Abeta. Abeta is a product of catabolism of the large type-I membrane protein APP. Two proteases, called beta- and gamma-secretase, endoproteolyze APP to liberate the Abeta peptide. Recently, the molecules responsible for these proteolytic activities have been identified. Several lines of evidence suggest that the PS1 and PS2 proteins are gamma-secretase, and the identity of beta-secretase has been shown to be the novel transmembrane aspartic protease, beta-site APP-cleaving enzyme 1 (BACE1; also called Asp2 and memapsin 2). BACE2, a protease homologous to BACE1, was also identified, and together the two enzymes define a new family of transmembrane aspartic proteases. BACE1 exhibits all the functional properties of beta-secretase, and as the key enzyme that initiates the formation of Abeta, BACE1 is an attractive drug target for AD. This review discusses the identification and initial characterization of BACE1 and BACE2, and summarizes recent studies of BACE1 knockout mice that have validated BACE1 as the authentic beta-secretase in vivo.
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Affiliation(s)
- Robert Vassar
- The Feinberg School of Medicine, Northwestern University, Department of Cell and Molecular Biology, Chicago, IL 60611, USA.
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Sambamurti K, Kinsey R, Maloney B, Ge YW, Lahiri DK. Gene structure and organization of the human beta-secretase (BACE) promoter. FASEB J 2004; 18:1034-6. [PMID: 15059975 DOI: 10.1096/fj.03-1378fje] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The first step in the generation of the amyloid-beta peptide (Abeta) deposited in the brains of patients with Alzheimer's disease (AD) is the processing of the larger Abeta precursor protein (APP) by an integral membrane aspartyl protease named the beta-site APP-cleaving enzyme (BACE). We present the genomic organization of the BACE gene. BACE mRNAs are synthesized as nine exons and eight introns from a 30.6 kb region of chromosome 11q23.2-11q23.3. Regulation of BACE may play an important role in regulating the levels of Abeta produced and is therefore likely to play an important role in AD. Herein, we report the cloning and detailed analysis of 3765 nucleotides of the promoter region of BACE and 364 nucleotides of the 5' untranslated region of the BACE mRNA (5' UTR). Characteristic "CAAT" and "TATA" boxes are absent within 1.5 kb of the transcription start site (TSS). The promoter region and 5' UTR contain multiple transcription factor binding sites, such as activator protein (AP)1, AP2, cAMP response element binding protein (CREB), estrogen responsive element (ERE), glucocorticoid responsive element (GRE), "GC" box, nuclear factor (NF)-kappaB, signal transducer and activator of transcription (STAT)1, stimulating protein (SP)1, metal-regulatory elements, and possible Zeste binding sites. Limited interspecies similarity was observed between the human sequence and corresponding genomic DNA from the rat and mouse sequences, but several transcription factor-binding sites are conserved. Thus, the BACE gene contains basal regulatory elements, inducible features and sites for regulated activity by various transcription factors. These results identify the important regions for functional analysis of the binding domains and neuron-specific expression (1). Such a study will allow us to further examine the possible role of changes in the promoter of BACE in AD pathogenesis.
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Affiliation(s)
- Kumar Sambamurti
- Medical University of South Carolina, Charleston, South Carolina, USA
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Affiliation(s)
- Michael S Wolfe
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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