TDP-43 is the major component protein of ubiquitin-positive inclusions in brains of patients with frontotemporal lobar degeneration (FTLD-TDP) or amyotrophic lateral sclerosis (ALS). Here, we report ...the characterization of prion-like properties of aggregated TDP-43 prepared from diseased brains. When insoluble TDP-43 from ALS or FTLD-TDP brains was introduced as seeds into SH-SY5Y cells expressing TDP-43, phosphorylated and ubiquitinated TDP-43 was aggregated in a self-templating manner. Immunoblot analyses revealed that the C-terminal fragments of insoluble TDP-43 characteristic of each disease type acted as seeds, inducing seed-dependent aggregation of TDP-43 in these cells. The seeding ability of insoluble TDP-43 was unaffected by proteinase treatment but was abrogated by formic acid. One subtype of TDP-43 aggregate was resistant to boiling treatment. The insoluble fraction from cells harboring TDP-43 aggregates could also trigger intracellular TDP-43 aggregation. These results indicate that insoluble TDP-43 has prion-like properties that may play a role in the progression of TDP-43 proteinopathy.
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•Insoluble TDP-43 from diseased brains shows prion-like properties•Intracellular TDP-43 exhibits seed-dependent and self-templating aggregation•Aggregates of TDP-43 propagate between cells partly via exosome•Suppression of aggregated TDP-43 propagation may be a target for therapy
TDP-43 is the major component protein of inclusions in the brains of patients with frontotemporal lobar degeneration or amyotrophic lateral sclerosis. Nonaka, Hasegawa, and colleagues find that insoluble TDP-43 from diseased brains has prion-like properties, including seeding ability in a self-templating manner, insensitivity of seeding to heat or proteinase treatment, and cell-to-cell propagation of insoluble protein. These findings suggest that the mechanism of disease progression in TDP-43 proteinopathy is similar to that in prion diseases.
Parkinson’s disease (PD) is characterized as a chronic and progressive neurodegenerative disorder, and the deposition of specific protein aggregates of α-synuclein, termed Lewy bodies, is evident in ...multiple brain regions of PD patients. Although there are several available medications to treat PD symptoms, these medications do not prevent the progression of the disease. Soluble epoxide hydrolase (sEH) plays a key role in inflammation associated with the pathogenesis of PD. Here we found that MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-induced neurotoxicity in the mouse striatum was attenuated by subsequent repeated administration of TPPU, a potent sEH inhibitor. Furthermore, deletion of the sEH gene protected against MPTP-induced neurotoxicity, while overexpression of sEH in the striatum significantly enhanced MPTP-induced neurotoxicity. Moreover, the expression of the sEH protein in the striatum from MPTP-treated mice or postmortem brain samples from patients with dementia of Lewy bodies (DLB) was significantly higher compared with control groups. Interestingly, there was a positive correlation between sEH expression and phosphorylation of α-synuclein in the striatum. Oxylipin analysis showed decreased levels of 8,9-epoxy-5Z,11Z,14Z-eicosatrienoic acid in the striatum of MPTP-treated mice, suggesting increased activity of sEH in this region. Interestingly, the expression of sEH mRNA in human PARK2 iPSC-derived neurons was higher than that of healthy control. Treatment with TPPU protected against apoptosis in human PARK2 iPSC-derived dopaminergic neurons. These findings suggest that increased activity of sEH in the striatum plays a key role in the pathogenesis of neurodegenerative disorders such as PD and DLB. Therefore, sEH may represent a promising therapeutic target for α-synuclein–related neurodegenerative disorders.
Polygenic risk scores suffer reduced accuracy in non-European populations, exacerbating health disparities. We propose PolyPred, a method that improves cross-population polygenic risk scores by ...combining two predictors: a new predictor that leverages functionally informed fine-mapping to estimate causal effects (instead of tagging effects), addressing linkage disequilibrium differences, and BOLT-LMM, a published predictor. When a large training sample is available in the non-European target population, we propose PolyPred
, which further incorporates the non-European training data. We applied PolyPred to 49 diseases/traits in four UK Biobank populations using UK Biobank British training data, and observed relative improvements versus BOLT-LMM ranging from +7% in south Asians to +32% in Africans, consistent with simulations. We applied PolyPred
to 23 diseases/traits in UK Biobank east Asians using both UK Biobank British and Biobank Japan training data, and observed improvements of +24% versus BOLT-LMM and +12% versus PolyPred. Summary statistics-based analogs of PolyPred and PolyPred
attained similar improvements.
Microglia-mediated neuroinflammation has been implicated in the pathogenesis of Alzheimer's disease (AD). Although microglia in aging and neurodegenerative disease model mice show a loss of ...homeostatic phenotype and activation of disease-associated microglia (DAM), a correlation between those phenotypes and the degree of neuronal cell loss has not been clarified. In this study, we performed RNA sequencing of microglia isolated from three representative neurodegenerative mouse models, App
with amyloid pathology, rTg4510 with tauopathy, and SOD1
with motor neuron disease by magnetic activated cell sorting. In parallel, gene expression patterns of the human precuneus with early Alzheimer's change (n = 11) and control brain (n = 14) were also analyzed by RNA sequencing. We found that a substantial reduction of homeostatic microglial genes in rTg4510 and SOD1
microglia, whereas DAM genes were uniformly upregulated in all mouse models. The reduction of homeostatic microglial genes was correlated with the degree of neuronal cell loss. In human precuneus with early AD pathology, reduced expression of genes related to microglia- and oligodendrocyte-specific markers was observed, although the expression of DAM genes was not upregulated. Our results implicate a loss of homeostatic microglial function in the progression of AD and other neurodegenerative diseases. Moreover, analyses of human precuneus also suggest loss of microglia and oligodendrocyte functions induced by early amyloid pathology in human.
Development of neurofibrillary tangles (NFTs) is a pathological hallmark in various neurodegenerative disorders including Alzheimer's disease (AD). Recently, we identified a granular tau oligomer ...having a pre-filamentous structure. To determine the role of this oligomer in NFT formation, we quantified the amount of granular tau oligomer in 21 frontal cortex samples, each displaying varying degrees of Braak-staged NFT pathology. Here we report that granular tau oligomer levels in frontal cortex were significantly increased, even in brains displaying Braak-stage I neuropathology, a stage at which clinical symptoms of AD and NFTs in frontal cortex are believed to be absent. This suggests that increases in granular tau oligomer levels occur before NFTs form and before individuals manifest clinical symptoms of AD. Increased granular tau oligomer levels, therefore, may lead to NFT formation in frontal cortex, eventually leading to the development of AD. Thus, increases in granular tau oligomer levels may represent a very early sign of NFT formation and AD.
Lewy body disease (LBD) is a spectrum of progressive neurodegenerative disorders characterized by the wide distribution of Lewy bodies and neurites in the central and peripheral nervous system (CNS, ...PNS). Clinical diagnoses include Parkinson’s disease (PD), dementia with Lewy bodies, or pure autonomic failure. All types of LBD are accompanied by non-motor symptoms (NMSs) including gastrointestinal dysfunctions such as constipation. Its relationship to Lewy body-related α-synucleinopathy (Lewy pathology) of the enteric nervous system (ENS) is attracting attention because it can precede the motor symptoms. To clarify the role of ENS Lewy pathology in disease progression, we performed a clinicopathological study using the Brain Bank for Aging Research in Japan. Five-hundred and eighteen cases were enrolled in the study. Lewy pathology of the CNS and PNS, including the lower esophagus as a representative of the ENS, was examined via autopsy findings. Results showed that one-third of older people (178 cases, 34%) exhibited Lewy pathology, of which 78 cases (43.8%) exhibited the pathology in the esophagus. In the esophageal wall, Auerbach’s plexus (41.6%) was most susceptible to the pathology, followed by the adventitia (33.1%) and Meissner’s plexus (14.6%). Lewy pathology of the esophagus was significantly associated with autonomic failures such as constipation (
p
< 0.0001) and among PNS regions, correlated the most with LBD progression (
r
= 0.95,
p
< 0.05). These findings suggest that the propagation of esophageal Lewy pathology is a predictive factor of LBD.
Intracellular accumulation of abnormal proteins with conformational changes is the defining neuropathological feature of neurodegenerative diseases. The pathogenic proteins that accumulate in ...patients' brains adopt an amyloid-like fibrous structure and exhibit various ultrastructural features. The biochemical analysis of pathogenic proteins in sarkosyl-insoluble fractions extracted from patients’ brains also shows disease-specific features. Intriguingly, these ultrastructural and biochemical features are common within the same disease group. These differences among the pathogenic proteins extracted from patients’ brains have important implications for definitive diagnosis of the disease, and also suggest the existence of pathogenic protein strains that contribute to the heterogeneity of pathogenesis in neurodegenerative diseases. Recent experimental evidence has shown that prion-like propagation of these pathogenic proteins from host cells to recipient cells underlies the onset and progression of neurodegenerative diseases. The reproduction of the pathological features that characterize each disease in cellular and animal models of prion-like propagation also implies that the structural differences in the pathogenic proteins are inherited in a prion-like manner. In this review, we summarize the ultrastructural and biochemical features of pathogenic proteins extracted from the brains of patients with neurodegenerative diseases that accumulate abnormal forms of tau, α-synuclein, and TDP-43, and we discuss how these disease-specific properties are maintained in the brain, based on recent experimental insights.
Tau is a microtubule-associated protein expressed in neuronal axons. Hyperphosphorylated tau is a major component of neurofibrillary tangles, a pathological hallmark of Alzheimer’s disease (AD). ...Hyperphosphorylated tau aggregates are also found in many neurodegenerative diseases, collectively referred to as “tauopathies,” and tau mutations are associated with familial frontotemporal lobar degeneration (FTLD). Previous studies have generated transgenic mice with mutant tau as tauopathy models, but nonhuman primates, which are more similar to humans, may be a better model to study tauopathies. For example, the common marmoset is poised as a nonhuman primate model for investigating the etiology of age-related neurodegenerative diseases. However, no biochemical studies of tau have been conducted in marmoset brains. Here, we investigated several important aspects of tau, including expression of different tau isoforms and its phosphorylation status, in the marmoset brain. We found that marmoset tau does not possess the “primate-unique motif” in its N-terminal domain. We also discovered that the tau isoform expression pattern in marmosets is more similar to that of mice than that of humans, with adult marmoset brains expressing only four-repeat tau isoforms as in adult mice but unlike in adult human brains. Of note, tau in brains of marmoset newborns was phosphorylated at several sites associated with AD pathology. However, in adult marmoset brains, much of this phosphorylation was lost, except for Ser-202 and Ser-404 phosphorylation. These results reveal key features of tau expression and phosphorylation in the marmoset brain, a potentially useful nonhuman primate model of neurodegenerative diseases.
Abstract Background Evaluation of brain β-amyloid by positron emission tomography (PET) imaging can assist in the diagnosis of Alzheimer disease (AD) and other dementias. Methods Open-label, ...nonrandomized, multicenter, phase 3 study to validate the18 F-labeled β-amyloid tracer florbetaben by comparing in vivo PET imaging with post-mortem histopathology. Results Brain images and tissue from 74 deceased subjects (of 216 trial participants) were analyzed. Forty-six of 47 neuritic β-amyloid-positive cases were read as PET positive, and 24 of 27 neuritic β-amyloid plaque-negative cases were read as PET negative (sensitivity 97.9% 95% confidence interval or CI 93.8–100%, specificity 88.9% 95% CI 77.0–100%). In a subgroup, a regional tissue-scan matched analysis was performed. In areas known to strongly accumulate β-amyloid plaques, sensitivity and specificity were 82% to 90%, and 86% to 95%, respectively. Conclusions Florbetaben PET shows high sensitivity and specificity for the detection of histopathology-confirmed neuritic β-amyloid plaques and may thus be a valuable adjunct to clinical diagnosis, particularly for the exclusion of AD. Trial registration ClinicalTrials.gov NCT01020838.
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