RNA editing is an epitranscriptomic modification, leading to targeted changes in RNA transcripts. It is mediated by the action of ADAR (adenosine deaminases acting on double-stranded (ds) RNA and APOBEC (apolipoprotein B mRNA editing enzyme catalytic polypeptide-like) deaminases and appears to play a major role in the pathogenesis of many diseases. Here, we assessed its role in experimental autoimmune encephalomyelitis (EAE), a widely used non-clinical model of autoimmune inflammatory diseases of the central nervous system (CNS), which resembles many aspects of human multiple sclerosis (MS). We have analyzed in silico data from microglia isolated at different timepoints through disease progression to identify the global editing events and validated the selected targets in murine tissue samples. To further evaluate the functional role of RNA editing, we induced EAE in transgenic animals lacking expression of APOBEC-1. We found that RNA-editing events, mediated by the APOBEC and ADAR deaminases, are significantly reduced throughout the course of disease, possibly affecting the protein expression necessary for normal neurological function. Moreover, the severity of the EAE model was significantly higher in APOBEC-1 knock-out mice, compared to wild-type controls. Our results implicate regulatory epitranscriptomic mechanisms in EAE pathogenesis that could be extrapolated to MS and other neurodegenerative disorders (NDs) with common clinical and molecular features.

Prion diseases are fatal neurodegenerative conditions that affect humans and animals. Rapid and accurate sequencing of the prion gene PRNP is paramount to human prion disease diagnosis and for animal surveillance programmes. Current methods for PRNP genotyping involve sequencing of small fragments within the protein-coding region. The contribution of variants in the non-coding regions of PRNP including large structural changes is poorly understood. Here, we used long-range PCR and Nanopore sequencing to sequence the full length of PRNP , including its regulatory region, in 25 samples from blood and brain of individuals with inherited or sporadic prion diseases. Nanopore sequencing detected the same variants as identified by Sanger sequencing, including repeat expansions/deletions. Nanopore identified additional single-nucleotide variants in the non-coding regions of PRNP , but no novel structural variants were discovered. Finally, we explored somatic mosaicism of PRNP ’s octapeptide repeat region, which is a hypothetical cause of sporadic prion disease. While we found changes consistent with somatic mutations, we demonstrate that they may have been generated by the PCR. Our study illustrates the accuracy of Nanopore sequencing for rapid and field prion disease diagnosis and highlights the need for single-molecule sequencing methods for the detection of somatic mutations.

ABSTRACTMammalian prion diseases are fatal and transmissible neurological conditions caused by the propagation of prions, self-replicating multimeric assemblies of misfolded forms of host cellular prion protein (PrP). The most common human form of the disease, sporadic Creutzfeldt-Jakob disease (sCJD), typically presents as a rapidly progressive dementia and has no effective treatments. Prion diseases are transmissible to laboratory rodents affording unprecedented opportunities to understand neurodegeneration in its evolving stages. Murine models are especially useful in prion research as they develop bona fide prion disease and recapitulate all biochemical and neuropathological hallmarks of human prion disease. Despite extensive studies investigating the changes in transcriptional profiles in prion diseases the mechanisms by which prion diseases induce cellular toxicity, including changes in gene expression profiles are yet to be fully characterized. This is at least in part because confounding effects related to brain cellular heterogeneity have not been resolved. Here, we took advantage of the recent developments in single-cell technologies and performed an unbiased whole-transcriptome single-nucleus transcriptomic analysis in prion disease.

Mammalian prions are lethal pathogens composed of fibrillar assemblies of misfolded prion protein. Human prion diseases are rare and usually rapidly fatal neurodegenerative disorders, the most common being sporadic Creutzfeldt-Jakob disease (sCJD). Variants in the gene that encodes prion protein ( PRNP ) are strong risk factors for sCJD, but although the condition has heritability similar to other neurodegenerative disorders, no other risk loci have yet been confirmed. By genome-wide association in European ancestry populations, we found three replicated loci (cases n=5208, within PRNP, STX6 , and GAL3ST1 ) and two further unreplicated loci were significant in gene-wide tests (within PDIA4, BMERB1 ). Exome sequencing in 407 sCJD cases, conditional and transcription analyses suggest that associations at PRNP and GAL3ST1 are likely to be caused by common variants that alter the protein sequence, whereas risk variants in STX6 and PDIA4 associate with increased expression of the major transcripts in disease-relevant brain regions. Alteration of STX6 expression does not modify prion propagation in a neuroblastoma cell model of mouse prion infection. We went on to analyse the proteins histologically in diseased tissue and examine the effects of risk variants on clinical phenotypes using deep longitudinal clinical cohort data. Risk SNPs in STX6 , a protein involved in the intracellular trafficking of proteins and vesicles, are shared with progressive supranuclear palsy, a neurodegenerative disease associated with the misfolded protein tau. We present the first evidence of statistically robust associations in sporadic human prion disease that implicate intracellular trafficking and sphingolipid metabolism.

BACKGROUND:Human prion diseases are rare and usually rapidly fatal neurodegenerative disorders, the most common being sporadic Creutzfeldt-Jakob disease (sCJD). Variants in the PRNP gene that encodes prion protein are strong risk factors for sCJD but, although the condition has similar heritability to other neurodegenerative disorders, no other genetic risk loci have been confirmed. We aimed to discover new genetic risk factors for sCJD, and their causal mechanisms. METHODS:We did a genome-wide association study of sCJD in European ancestry populations (patients diagnosed with probable or definite sCJD identified at national CJD referral centres) with a two-stage study design using genotyping arrays and exome sequencing. Conditional, transcriptional, and histological analyses of implicated genes and proteins in brain tissues, and tests of the effects of risk variants on clinical phenotypes, were done using deep longitudinal clinical cohort data. Control data from healthy individuals were obtained from publicly available datasets matched for country. FINDINGS:Samples from 5208 cases were obtained between 1990 and 2014. We found 41 genome-wide significant single nucleotide polymorphisms (SNPs) and independently replicated findings at three loci associated with sCJD risk; within PRNP (rs1799990; additive model odds ratio [OR] 1·23 [95% CI 1·17-1·30], p=2·68 × 10-15; heterozygous model p=1·01 × 10-135), STX6 (rs3747957; OR 1·16 [1·10-1·22], p=9·74 × 10-9), and GAL3ST1 (rs2267161; OR 1·18 [1·12-1·25], p=8·60 × 10-10). Follow-up analyses showed that associations at PRNP and GAL3ST1 are likely to be caused by common variants that alter the protein sequence, whereas risk variants in STX6 are associated with increased expression of the major transcripts in disease-relevant brain regions. INTERPRETATION:We present, to our knowledge, the first evidence of statistically robust genetic associations in sporadic human prion disease that implicate intracellular trafficking and sphingolipid metabolism as molecular causal mechanisms. Risk SNPs in STX6 are shared with progressive supranuclear palsy, a neurodegenerative disease associated with misfolding of protein tau, indicating that sCJD might share the same causal mechanisms as prion-like disorders. FUNDING:Medical Research Council and the UK National Institute of Health Research in part through the Biomedical Research Centre at University College London Hospitals National Health Service Foundation Trust.

Introduction: ApolipoproteinE (ApoE) is themost important genetic risk factor forAlzheimer’s disease *Corresponding a 3448 4046. E-mail address: s. https://doi.org/10.1016 2352-8729/ 2019 Th (http://creativecommo (AD),withApoE4 thought to enhance andaccelerate amyloid-b (Ab) pathology.ApoE4has recently been described to increase neurodegeneration in a mouse model of frontotemporal dementia (FTD), in vitro, and in patients, demonstrating that ApoE4modifies tauopathy independently of Ab. This raises the questionwhetherApoEgenotype alsomodifies the clinical phenotype inpatientswithFTDwith tau pathology. Methods: We analyzed 704 patients with FTD, including a genetically and neuropathologically confirmed subset, and 452 healthy elderly controls. We compared ApoE4 genotype frequency and age at onset in tau1 or TDP431 FTD patients with or without Ab copathology. Results: The ApoE4 genotype lowered age at onset in patients with FTD and tau pathology, particularly once accounting for confounding effects of Ab pathology. Discussion: We conclude that ApoE4 accelerates neurodegeneration in FTD patients with MAPT mutations or FTLD-tau pathology, independent of Ab. 2019 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer’s Association. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Apolipoprotein E (ApoE) is the strongest known common genetic risk factor for Alzheimer’s disease (AD) [1,2]. Relative to the most common allele (ApoE3), ApoE4 is associatedwith an increased risk of late-onsetADand an earlier age at onset (AAO); conversely, ApoE2 confers lower risk and later onset [2,3].Multiple lines of evidence suggest that ApoE4 risk in AD principally relates to enhanced and accelerated cerebral Ab pathology [4]. More precisely, ApoE4 appears to accelerate the early seeding of amyloid pathology, most likely by decreasing Ab clearance and enhancing Ab aggregation [5]. Shi et al. recently described how ApoE4 increases the uthor. Tel.: 144 (0) 20 3448 4037; Fax: 144 (0) 20 mead@prion.ucl.ac.uk /j.dadm.2019.01.010 e Authors. Published by Elsevier Inc. on behalf of the Alzh ns.org/licenses/by/4.0/). burden of cerebral tau pathology, neuroinflammation, and brain atrophy in a P301S mouse model of frontotemporal dementia (FTD) and in vitro; they also demonstrated that in patients with a primary tauopathy, ApoE4was associated with more severe regional neurodegeneration and thatApoE41ADpatients with amyloid-b (Ab) pathology showed faster disease progression [6]. New evidence fromShi et al. demonstrates thatApoE4 modifies tauopathy independent of Ab, raising the question whether ApoE genotype also influences risk or modifies the clinical phenotype in patientswith primary tauopathies. Several studies report an association between ApoE and FTD with a protective effect for ApoE2 and an increased risk conferred by ApoE4 [729], whereas another shows no association [10]. A recent publication demonstrated a deleterious effect of ApoE2 in a tau transgenic mouse model [11]. However, interpretations of the associations of ApoE with the clinical eimer’s Association. This is an open access article under the CC BY license C. Koriath et al. / Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring 11 (2019) 277-280 278 syndrome of FTD are complicated by two factors: frontal variant AD can be misdiagnosed for FTD, and the fact that the FTD syndrome comprises tau, TDP-43, or other pathologies. Prompted byShi et al. [6],we therefore analyzed existing data we held on 704 patients with FTD and 452 healthy elderly controls using SPSS25 to test the hypothesis that ApoE genotype has a modifying effect on clinical phenotype in those with or expected to have tau pathology defined by a highly penetrantMAPT gene mutation or by neuropathological examination.We found that theApoE4 genotype lowered age at clinical onset in patients with dementia and tau pathology, and was a particularly strong effect once the confounding effects of amyloid b pathology were taken into account. The patients in this FTD cohort were previously tested for causative genetic mutations [12] and are described in Table 1. Patients with causative mutations in genes not typically associatedwithFTDwereexcluded fromthepresent analysis. Patients were analyzed in groups based on genetic and/or neuropathological data, patients in whom no causative mutation had been identified and for whom no neuropathological data were available either were classified as “clinically diagnosed” and not included in analyses of genetic subgroups. Dementia and personality change were the predominant symptoms in our series (54.7% 33.3% “behavioral type FTD”, 21.4% “FTD”, 1.1% “Dementia”), followed by aphasia (31.8% 16.9% progressive nonfluent aphasia, 13.1% semantic dementia, 1.8% logopenic progressive aphasia) and additional motor or muscular symptoms (11.5% 6.0% corticobasal degeneration,

Prion diseases are fatal neurodegenerative disorders caused by misfolding of the normal prion protein into an infectious cellular pathogen. Clinically characterized by rapidly progressive dementia and accounting for 85% of human prion disease cases, sporadic Creutzfeldt-Jakob disease (sCJD) is the prevalent human prion disease. Although sCJD neuropathological hallmarks are well-known, associated molecular alterations are elusive due to rapid progression and absence of preclinical stages. To investigate transcriptome alterations during disease progression, we utilized tg340-PRNP129MM mice infected with postmortem material from sCJD patients of the most susceptible genotype (MM1 subtype), a sCJD model that faithfully recapitulates the molecular and pathological alterations of the human disease. Here we report that transcriptomic analyses from brain cortex in the context of disease progression, reveal epitranscriptomic alterations (specifically altered RNA edited pathway profiles, eg., ER stress, lysosome) that are characteristic and possibly protective mainly for preclinical and clinical disease stages. Our results implicate regulatory epitranscriptomic mechanisms in prion disease neuropathogenesis, whereby RNA-editing targets in a humanized sCJD mouse model were confirmed in pathological human autopsy material.

Abstract Introduction Apolipoprotein E (ApoE) is the most important genetic risk factor for Alzheimer's disease (AD), with ApoE4 thought to enhance and accelerate amyloid‐β (Aβ) pathology. ApoE4 has recently been described to increase neurodegeneration in a mouse model of frontotemporal dementia (FTD), in vitro, and in patients, demonstrating that ApoE4 modifies tauopathy independently of Aβ. This raises the question whether ApoE genotype also modifies the clinical phenotype in patients with FTD with tau pathology. Methods We analyzed 704 patients with FTD, including a genetically and neuropathologically confirmed subset, and 452 healthy elderly controls. We compared ApoE4 genotype frequency and age at onset in tau+ or TDP43+ FTD patients with or without Aβ copathology. Results The ApoE4 genotype lowered age at onset in patients with FTD and tau pathology, particularly once accounting for confounding effects of Aβ pathology. Discussion We conclude that ApoE4 accelerates neurodegeneration in FTD patients with MAPT mutations or FTLD‐tau pathology, independent of Aβ.

Primary infection by cytomegalovirus in immunocompetent patients is usually unapparent. We report a case of severe acute cytomegalovirus infection in a young immunocompetent male with pulmonary and hepatic involvement and portal hypertension who recovered without specific antiviral therapy with complete resolution of sonographic signs of portal hypertension after 6 months.