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Streit WJ, Khoshbouei H, Bechmann I. The Role of Microglia in Sporadic Alzheimer's Disease. J Alzheimers Dis 2020; 79:961-968. [PMID: 33361603 DOI: 10.3233/jad-201248] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microglia constitute the brain's immune system and their involvement in Alzheimer's disease has been discussed. Commonly, and in line with the amyloid/neuroinflammation cascade hypothesis, microglia have been portrayed as potentially dangerous immune effector cells thought to be overactivated by amyloid and producing neurotoxic inflammatory mediators that lead to neurofibrillary degeneration. We disagree with this theory and offer as an alternative the microglial dysfunction theory stating that microglia become impaired in their normally neuroprotective roles because of aging, i.e., they become senescent and aging neurons degenerate because they lack the needed microglial support for their survival. Thus, while the amyloid cascade theory relies primarily on genetic data, the dysfunction theory incorporates aging as a critical etiological factor. Aging is the greatest risk factor for the sporadic (late-onset) and most common form of Alzheimer's disease, where fully penetrant genetic mutations are absent. In this review, we lay out and discuss the human evidence that supports senescent microglial dysfunction and conflicts with the amyloid/neuroinflammation idea.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | | | - Ingo Bechmann
- Anatomical Institute, University of Leipzig, Leipzig, Germany
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Wu HY, Kuo PC, Wang YT, Lin HT, Roe AD, Wang BY, Han CL, Hyman BT, Chen YJ, Tai HC. β-Amyloid Induces Pathology-Related Patterns of Tau Hyperphosphorylation at Synaptic Terminals. J Neuropathol Exp Neurol 2019; 77:814-826. [PMID: 30016458 DOI: 10.1093/jnen/nly059] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A synergy between β-amyloid (Aβ) and tau appears to occur in Alzheimer disease (AD), but the mechanisms of interaction, and potential locations, are little understood. This study investigates the possibility of such interactions within the cortical synaptic compartments of APP/PS1 mice. We used label-free quantitative mass spectrometry to study the phosphoproteome of synaptosomes, covering 2400 phosphopeptides and providing an unbiased survey of phosphorylation changes associated with amyloid pathology. Hyperphosphorylation was detected on 36 synaptic proteins, many of which are associated with the cytoskeleton. Importantly, tau is one of the most hyperphosphorylated proteins at the synapse, upregulated at both proline-directed kinase (PDK) sites (S199/S202, S396/S404) and nonPDK sites (S400). These PDK sites correspond to well-known pathological tau epitopes in AD patients, recognized by AT8 and PHF-1 antibodies, respectively. Hyperphosphorylation at S199/S202, a rarely examined combination, was further validated in patient-derived human synaptosomes by immunoblotting. Global surveys of upregulated phosphosites revealed 2 potential kinase motifs, which resemble those of cyclin-dependent kinase 5 (CDK5, a PDK) and casein kinase II (CK2, a nonPDK). Our data demonstrate that, within synaptic compartments, amyloid pathology is associated with tau hyperphosphorylation at disease-relevant epitopes. This provides a plausible mechanism by which Aβ promotes the spreading of tauopathy.
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Affiliation(s)
- Hsin-Yi Wu
- Instrumentation Center, National Taiwan University, Taipei, Taiwan
| | - Po-Cheng Kuo
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Yi-Ting Wang
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hao-Tai Lin
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Allyson D Roe
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Bo Y Wang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Chia-Li Han
- Master Program for Clinical Pharmacogenomics and Pharmacoproteomics, College of Pharmacy, Taipei Medical University, Taipei, Taiwan
| | - Bradley T Hyman
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yu-Ju Chen
- Department of Chemistry, National Taiwan University, Taipei, Taiwan.,Institute of Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hwan-Ching Tai
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
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Martin LJ, Wong M, Hanaford A. Neonatal Brain Injury and Genetic Causes of Adult-Onset Neurodegenerative Disease in Mice Interact With Effects on Acute and Late Outcomes. Front Neurol 2019; 10:635. [PMID: 31275228 PMCID: PMC6591316 DOI: 10.3389/fneur.2019.00635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 05/30/2019] [Indexed: 12/27/2022] Open
Abstract
Neonatal brain damage and age-related neurodegenerative disease share many common mechanisms of injury involving mitochondriopathy, oxidative stress, excitotoxicity, inflammation, and neuronal cell death. We hypothesized that genes causing adult-onset neurodegeneration can influence acute outcome after CNS injury at immaturity and on the subsequent development of chronic disability after early-life brain injury. In two different transgenic (Tg) mouse models of adult-onset neurodegenerative disease, a human A53T-α-synuclein (hαSyn) model of Parkinson's disease (PD) and a human G93A-superoxide dismutase-1(hSOD1) model of amyotrophic lateral sclerosis (ALS), mortality and survivor morbidity were significantly greater than non-Tg mice and a Tg mouse model of Alzheimer's disease after neonatal traumatic brain injury (TBI). Acutely after brain injury, hαSyn neonatal mice showed a marked enhancement of protein oxidative damage in forebrain, brain regional mitochondrial oxidative metabolism, and mitochondriopathy. Extreme protein oxidative damage was also observed in neonatal mutant SOD1 mice after TBI. At 1 month of age, neuropathology in forebrain, midbrain, and brainstem of hαSyn mice with neonatal TBI was greater compared to sham hαSyn mice. Surviving hαSyn mice with TBI showed increased hαSyn aggregation and nitration and developed adult-onset disease months sooner and died earlier than non-injured hαSyn mice. Surviving hSOD1 mice with TBI also developed adult-onset disease and died sooner than non-injured hSOD1 mice. We conclude that mutant genes causing PD and ALS in humans have significant impact on mortality and morbidity after early-life brain injury and on age-related disease onset and proteinopathy in mice. This study provides novel insight into genetic determinants of poor outcomes after acute injury to the neonatal brain and how early-life brain injury can influence adult-onset neurodegenerative disease during aging.
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Affiliation(s)
- Lee J Martin
- Division of Neuropathology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Pathobiology Graduate Training Program, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Margaret Wong
- Division of Neuropathology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Allison Hanaford
- Pathobiology Graduate Training Program, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Neprilysin degrades murine Amyloid-β (Aβ) more efficiently than human Aβ: Further implication for species-specific amyloid accumulation. Neurosci Lett 2018; 686:74-79. [DOI: 10.1016/j.neulet.2018.08.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 08/14/2018] [Accepted: 08/21/2018] [Indexed: 01/19/2023]
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Xu G, Ran Y, Fromholt SE, Fu C, Yachnis AT, Golde TE, Borchelt DR. Murine Aβ over-production produces diffuse and compact Alzheimer-type amyloid deposits. Acta Neuropathol Commun 2015; 3:72. [PMID: 26566997 PMCID: PMC4644287 DOI: 10.1186/s40478-015-0252-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 11/02/2015] [Indexed: 01/31/2023] Open
Abstract
INTRODUCTION Transgenic overexpression of amyloid precursor protein (APP) genes that are either entirely human in sequence or have humanized Aβ sequences can produce Alzheimer-type amyloidosis in mice, provided the transgenes also encode mutations linked to familial Alzheimer's Disease (FAD). Although transgenic mice have been produced that overexpress wild-type mouse APP, no mice have been generated that express mouse APP with FAD mutations. Here we describe two different versions of such mice that produce amyloid deposits consisting of entirely of mouse Aβ peptides. One line of mice co-expresses mouse APP-Swedish (moAPPswe) with a human presenilin exon-9 deleted variant (PS1dE9) and another line expresses mouse APP-Swedish/Indiana (APPsi) using tetracycline-regulated vectors (tet.moAPPsi). RESULTS Both lines of mice that produce mouse Aβ develop amyloid deposits, with the moAPPswe/PS1dE9 mice developing extracellular compact, cored, neuritic deposits that primarily localize to white matter tracts and meningial layers, whereas the tet.moAPPsi mice developed extracellular diffuse cortical/hippocampal deposits distributed throughout the parenchyma. CONCLUSIONS These findings demonstrate that murine Aβ peptides have the capacity to produce amyloid deposits that are morphologically similar to deposits found in human AD provided the murine APP gene harbors mutations linked to human FAD.
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Streit WJ, Xue QS, Braak H, del Tredici K. Presence of severe neuroinflammation does not intensify neurofibrillary degeneration in human brain. Glia 2013; 62:96-105. [DOI: 10.1002/glia.22589] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 09/17/2013] [Accepted: 10/02/2013] [Indexed: 01/12/2023]
Affiliation(s)
- Wolfgang J. Streit
- Department of Neuroscience; University of Florida College of Medicine and McKnight Brain Institute; Gainesville Florida
| | - Qing-Shan Xue
- Department of Neuroscience; University of Florida College of Medicine and McKnight Brain Institute; Gainesville Florida
| | - Heiko Braak
- Clinical Neuroanatomy; Department of Neurology; University of Ulm; Ulm Germany
| | - Kelly del Tredici
- Clinical Neuroanatomy; Department of Neurology; University of Ulm; Ulm Germany
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Brain homogenates from human tauopathies induce tau inclusions in mouse brain. Proc Natl Acad Sci U S A 2013; 110:9535-40. [PMID: 23690619 DOI: 10.1073/pnas.1301175110] [Citation(s) in RCA: 532] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Filamentous inclusions made of hyperphosphorylated tau are characteristic of numerous human neurodegenerative diseases, including Alzheimer's disease, tangle-only dementia, Pick disease, argyrophilic grain disease (AGD), progressive supranuclear palsy, and corticobasal degeneration. In Alzheimer's disease and AGD, it has been shown that filamentous tau appears to spread in a stereotypic manner as the disease progresses. We previously demonstrated that the injection of brain extracts from human mutant P301S tau-expressing transgenic mice into the brains of mice transgenic for wild-type human tau (line ALZ17) resulted in the assembly of wild-type human tau into filaments and the spreading of tau inclusions from the injection sites to anatomically connected brain regions. Here we injected brain extracts from humans who had died with various tauopathies into the hippocampus and cerebral cortex of ALZ17 mice. Argyrophilic tau inclusions formed in all cases and following the injection of the corresponding brain extracts, we recapitulated the hallmark lesions of AGD, PSP and CBD. Similar inclusions also formed after intracerebral injection of brain homogenates from human tauopathies into nontransgenic mice. Moreover, the induced formation of tau aggregates could be propagated between mouse brains. These findings suggest that once tau aggregates have formed in discrete brain areas, they become self-propagating and spread in a prion-like manner.
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Silverberg GD, Miller MC, Machan JT, Johanson CE, Caralopoulos IN, Pascale CL, Heile A, Klinge PM. Amyloid and Tau accumulate in the brains of aged hydrocephalic rats. Brain Res 2010; 1317:286-96. [DOI: 10.1016/j.brainres.2009.12.065] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 12/20/2009] [Accepted: 12/21/2009] [Indexed: 10/20/2022]
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Selective detection, quantification, and subcellular location of alpha-synuclein aggregates with a protein aggregate filtration assay. Biotechniques 2008; 44:403-11. [PMID: 18361794 DOI: 10.2144/000112691] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy are caused by alpha-synuclein aggregates. At present, there is no good biochemical method defining alpha-synuclein aggregates formed in vivo versus oligomers as a means to investigate alpha-synuclein aggregation and its mechanisms of neurodegeneration. A simple method, therefore, for the selective and sensitive detection of alpha-synuclein aggregates suited for screening purposes would be useful. Since in contrast to prions a proper detection of alpha-synuclein aggregates by Western blot analysis is difficult, we developed a protein aggregate filtration (PAF) assay. It takes advantage of the inherent insolubility of aggregated alpha-synuclein using microfiltration to separate it from soluble isoforms. For the first time, this assay even makes quantitative comparisons possible. We describe how the PAF assay can be applied to human brain tissue and animal and cell culture models, as well as used as a screening method for the subcellular location of alpha-synuclein aggregates. Since it detects the pathological isoform instead of surrogate markers, the PAF assay may have also potential in diagnosis of PD and DLB.
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Geddes JW. alpha-Synuclein: a potent inducer of tau pathology. Exp Neurol 2005; 192:244-50. [PMID: 15755542 DOI: 10.1016/j.expneurol.2004.12.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/12/2004] [Accepted: 12/01/2004] [Indexed: 12/29/2022]
Affiliation(s)
- James W Geddes
- Spinal Cord and Brain Injury Research Center and Sanders-Brown Center on Aging, University of Kentucky, 800 South Limestone Street, Lexington, KY 40536-0230, USA.
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Kimura N, Yanagisawa K, Terao K, Ono F, Sakakibara I, Ishii Y, Kyuwa S, Yoshikawa Y. Age-related changes of intracellular Abeta in cynomolgus monkey brains. Neuropathol Appl Neurobiol 2005; 31:170-80. [PMID: 15771710 DOI: 10.1111/j.1365-2990.2004.00624.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To confirm the intracellular accumulation of amyloid beta-protein (Abeta), we carefully performed immunohistochemistry using brains of cynomolgus monkeys of various ages. Cortical neurones and their large neurites were immunostained with antibodies against Abeta in young monkey brains. In aged monkey brains, intracellular Abeta localized within cortical neurones; no clear association was found between the presence of intracellular Abeta and senile plaques (SPs). Interestingly, we did not observe Abeta-immunoreactive cortical neurones in brains fixed with neutral buffered formalin. Western blot analyses of microsomal and nerve ending fractions derived from the brains of young to aged monkeys revealed that intracellular Abeta generation changed with age. In the microsomal fraction, the amount of Abeta42 significantly increased in brains from older monkeys (>30 years of age), and the amount of Abeta43 significantly decreased with age in the microsomal fraction. The amount of Abeta40 remained the same regardless of age. Biochemical analyses also showed that intracellular levels of each of these Abeta molecules significantly increased with age in nerve ending fractions. As we previously observed that a similar accumulation of presenilin1, beta-amyloid precursor protein (APP) and APP C-terminal fragment cleaved by beta-secretase in the nerve ending fractions obtained from brains with SPs, the accumulation of intracellular Abeta in this fraction may be closely related to formation of spontaneous SPs with age. Taken together, these results suggest that intensive investigation of age-related changes in the nerve ending will contribute to a better understanding of the pathogenesis of age-related neurodegenerative disorders such as sporadic Alzheimer's disease.
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Affiliation(s)
- N Kimura
- Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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Stoothoff WH, Johnson GVW. Tau phosphorylation: physiological and pathological consequences. Biochim Biophys Acta Mol Basis Dis 2005; 1739:280-97. [PMID: 15615646 DOI: 10.1016/j.bbadis.2004.06.017] [Citation(s) in RCA: 308] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Accepted: 06/02/2004] [Indexed: 11/24/2022]
Abstract
The microtubule-associated protein tau, abundant in neurons, has gained notoriety due to the fact that it is deposited in cells as fibrillar lesions in numerous neurodegenerative diseases, and most notably Alzheimer's disease. Regulation of microtubule dynamics is the most well-recognized function of tau, but it is becoming increasingly evident that tau plays additional roles in the cell. The functions of tau are regulated by site-specific phosphorylation events, which if dysregulated, as they are in the disease state, result in tau dysfunction and mislocalization, which is potentially followed by tau polymerization, neuronal dysfunction and death. Given the increasing evidence that a disruption in the normal phosphorylation state of tau plays a key role in the pathogenic events that occur in Alzheimer's disease and other neurodegenerative conditions, it is of crucial importance that the protein kinases and phosphatases that regulate tau phosphorylation in vivo as well as the signaling cascades that regulate them be identified. This review focuses on recent literature pertaining to the regulation of tau phosphorylation and function in cell culture and animal model systems, and the role that a dysregulation of tau phosphorylation may play in the neuronal dysfunction and death that occur in neurodegenerative diseases that have tau pathology.
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Affiliation(s)
- William H Stoothoff
- Department of Psychiatry, School of Medicine, University of Alabama at Birmingham, 1061 Sparks Center, 1720 7th Avenue South, Birmingham, AL 35294-0017, USA
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