scholarly journals Epigenetic signatures of methylated DNA cytosine in Alzheimer’s disease

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw2880 ◽  
Author(s):  
Irfete S. Fetahu ◽  
Dingailu Ma ◽  
Kimberlie Rabidou ◽  
Christian Argueta ◽  
Michael Smith ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurodegenerative Disorder ◽  
Epigenetic Alterations ◽  
Methylated Dna ◽  
Genome Wide ◽  
Hydroxymethyl Cytosine ◽  
Methyl Cytosine ◽  
Prognostic Implications ◽  
Epigenetic Signatures

Alzheimer’s disease (AD), a progressive neurodegenerative disorder, is the most common untreatable form of dementia. Identifying molecular biomarkers that allow early detection remains a key challenge in the diagnosis, treatment, and prognostic evaluation of the disease. Here, we report a novel experimental and analytical model characterizing epigenetic alterations during AD onset and progression. We generated the first integrated base-resolution genome-wide maps of the distribution of 5-methyl-cytosine (5mC), 5-hydroxymethyl-cytosine (5hmC), and 5-formyl/carboxy-cytosine (5fC/caC) in normal and AD neurons. We identified 27 AD region–specific and 39 CpG site–specific epigenetic signatures that were independently validated across our familial and sporadic AD models, and in an independent clinical cohort. Thus, our work establishes a new model and strategy to study the epigenetic alterations underlying AD onset and progression and provides a set of highly reliable AD-specific epigenetic signatures that may have early diagnostic and prognostic implications.

scholarly journals Advances in Genetics and Epigenetic Alterations in Alzheimer’s Disease: A Notion for Therapeutic Treatment

Genes ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1959
Author(s):  
Rubén Rabaneda-Bueno ◽  
Beatriz Mena-Montes ◽  
Sara Torres-Castro ◽  
Norma Torres-Carrillo ◽  
Nora Magdalena Torres-Carrillo
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Dna Sequences ◽  
Neurodegenerative Disorder ◽  
Neurological Diseases ◽  
Epigenetic Alterations ◽  
Age Related ◽  
Genome Wide ◽  
Massive Sequencing

Alzheimer’s disease (AD) is a disabling neurodegenerative disorder that leads to long-term functional and cognitive impairment and greatly reduces life expectancy. Early genetic studies focused on tracking variations in genome-wide DNA sequences discovered several polymorphisms and novel susceptibility genes associated with AD. However, despite the numerous risk factors already identified, there is still no fully satisfactory explanation for the mechanisms underlying the onset of the disease. Also, as with other complex human diseases, the causes of low heritability are unclear. Epigenetic mechanisms, in which changes in gene expression do not depend on changes in genotype, have attracted considerable attention in recent years and are key to understanding the processes that influence age-related changes and various neurological diseases. With the recent use of massive sequencing techniques, methods for studying epigenome variations in AD have also evolved tremendously, allowing the discovery of differentially expressed disease traits under different conditions and experimental settings. This is important for understanding disease development and for unlocking new potential AD therapies. In this work, we outline the genomic and epigenomic components involved in the initiation and development of AD and identify potentially effective therapeutic targets for disease control.

scholarly journals Summary-Based Methylome-Wide Association Analyses Suggest Potential Genetically Driven Epigenetic Heterogeneity of Alzheimer’s Disease

2020 ◽  
Vol 9 (5) ◽  
pp. 1489
Author(s):  
Alireza Nazarian ◽  
Anatoliy I. Yashin ◽  
Alexander M. Kulminski
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurodegenerative Disorder ◽  
Tissue Samples ◽  
Significance Level ◽  
Association Analyses ◽  
Functional Studies ◽  
Genome Wide ◽  
Summary Data

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder with no curative treatment available. Exploring the genetic and non-genetic contributors to AD pathogenesis is essential to better understand its underlying biological mechanisms, and to develop novel preventive and therapeutic strategies. We investigated potential genetically driven epigenetic heterogeneity of AD through summary data-based Mendelian randomization (SMR), which combined results from our previous genome-wide association analyses with those from two publicly available methylation quantitative trait loci studies of blood and brain tissue samples. We found that 152 probes corresponding to 113 genes were epigenetically associated with AD at a Bonferroni-adjusted significance level of 5.49E-07. Of these, 10 genes had significant probes in both brain-specific and blood-based analyses. Comparing males vs. females and hypertensive vs. non-hypertensive subjects, we found that 22 and 79 probes had group-specific associations with AD, respectively, suggesting a potential role for such epigenetic modifications in the heterogeneous nature of AD. Our analyses provided stronger evidence for possible roles of four genes (i.e., AIM2, C16orf80, DGUOK, and ST14) in AD pathogenesis as they were also transcriptionally associated with AD. The identified associations suggest a list of prioritized genes for follow-up functional studies and advance our understanding of AD pathogenesis.

scholarly journals System-Level Analysis of Alzheimer’s Disease Prioritizes Candidate Genes for Neurodegeneration

2021 ◽  
Vol 12 ◽  
Author(s):  
Jeffrey L. Brabec ◽  
Montana Kay Lara ◽  
Anna L. Tyler ◽  
J. Matthew Mahoney
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Genome Wide Association Study ◽  
Neurodegenerative Disorder ◽  
Disease Status ◽  
Cumulative Distribution ◽  
System Level ◽  
Risk Genes ◽  
Genome Wide ◽  
Prioritization Method

Alzheimer’s disease (AD) is a debilitating neurodegenerative disorder. Since the advent of the genome-wide association study (GWAS) we have come to understand much about the genes involved in AD heritability and pathophysiology. Large case-control meta-GWAS studies have increased our ability to prioritize weaker effect alleles, while the recent development of network-based functional prediction has provided a mechanism by which we can use machine learning to reprioritize GWAS hits in the functional context of relevant brain tissues like the hippocampus and amygdala. In parallel with these developments, groups like the Alzheimer’s Disease Neuroimaging Initiative (ADNI) have compiled rich compendia of AD patient data including genotype and biomarker information, including derived volume measures for relevant structures like the hippocampus and the amygdala. In this study we wanted to identify genes involved in AD-related atrophy of these two structures, which are often critically impaired over the course of the disease. To do this we developed a combined score prioritization method which uses the cumulative distribution function of a gene’s functional and positional score, to prioritize top genes that not only segregate with disease status, but also with hippocampal and amygdalar atrophy. Our method identified a mix of genes that had previously been identified in AD GWAS including APOE, TOMM40, and NECTIN2(PVRL2) and several others that have not been identified in AD genetic studies, but play integral roles in AD-effected functional pathways including IQSEC1, PFN1, and PAK2. Our findings support the viability of our novel combined score as a method for prioritizing region- and even cell-specific AD risk genes.

scholarly journals Ethnicity-specific and overlapping alterations of brain hydroxymethylome in Alzheimer’s disease

2019 ◽  
Vol 29 (1) ◽  
pp. 149-158
Author(s):  
Lixia Qin ◽  
Qian Xu ◽  
Ziyi Li ◽  
Li Chen ◽  
Yujing Li ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Frontal Cortex ◽  
Cytosine Methylation ◽  
Neurodegenerative Disorder ◽  
Late Onset ◽  
Hypoxia Inducible Factor ◽  
Specific Gene ◽  
Dna Hydroxymethylation ◽  
Genome Wide

Abstract 5-Methylcytosine (5mC), generated through the covalent addition of a methyl group to the fifth carbon of cytosine, is the most prevalent DNA modification in humans and functions as a critical player in the regulation of tissue and cell-specific gene expression. 5mC can be oxidized to 5-hydroxymethylcytosine (5hmC) by ten–eleven translocation (TET) enzymes, which is enriched in brain. Alzheimer’s disease (AD) is the most common neurodegenerative disorder, and several studies using the samples collected from Caucasian cohorts have found that epigenetics, particularly cytosine methylation, could play a role in the etiological process of AD. However, little research has been conducted using the samples of other ethnic groups. Here we generated genome-wide profiles of both 5mC and 5hmC in human frontal cortex tissues from late-onset Chinese AD patients and cognitively normal controls. We identified both Chinese-specific and overlapping differentially hydroxymethylated regions (DhMRs) with Caucasian cohorts. Pathway analyses revealed specific pathways enriched among Chinese-specific DhMRs, as well as the shared DhMRs with Caucasian cohorts. Furthermore, two important transcription factor-binding motifs, hypoxia-inducible factor 2α (HIF2α) and hypoxia-inducible factor 1α (HIF1α), were enriched in the DhMRs. Our analyses provide the first genome-wide profiling of DNA hydroxymethylation of the frontal cortex of AD patients from China, emphasizing an important role of 5hmC in AD pathogenesis and highlighting both ethnicity-specific and overlapping changes of brain hydroxymethylome in AD.

scholarly journals A histone acetylome-wide association study of Alzheimer’s disease: neuropathology-associated regulatory variation in the human entorhinal cortex

2017 ◽  
Author(s):  
Sarah J. Marzi ◽  
Teodora Ribarska ◽  
Adam R. Smith ◽  
Eilis Hannon ◽  
Jeremie Poschmann ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Entorhinal Cortex ◽  
Neurodegenerative Disorder ◽  
Late Onset ◽  
Association Studies ◽  
Amyloid Β ◽  
Genomic Variation ◽  
Genome Wide Association Studies ◽  
Genome Wide

AbstractAlzheimer’s disease (AD) is a chronic neurodegenerative disorder characterized by the progressive accumulation of amyloid-β (Aβ) plaques and neurofibrillary tangles in the neocortex. Recent studies have implicated a role for regulatory genomic variation in AD progression, finding widespread evidence for altered DNA methylation associated with neuropathology. To date, however, no study has systematically examined other types of regulatory genomic modifications in AD. In this study, we quantified genome-wide patterns of lysine H3K27 acetylation (H3K27ac) - a robust mark of active enhancers and promoters that is strongly correlated with gene expression and transcription factor binding - in entorhinal cortex samples from AD cases and matched controls (n = 47) using chromatin immunoprecipitation followed by highly parallel sequencing (ChIP-seq). Across ~182,000 robustly detected H3K27ac peak regions, we found widespread acetylomic variation associated with AD neuropathology, identifying 4,162 differential peaks (FDR < 0.05) between AD cases and controls. These differentially acetylated peaks are enriched in disease-specific biological pathways and include regions annotated to multiple genes directly involved in the progression of Aβ and tau pathology (e.g. APP, PSEN1, PSEN2, MAPT), as well as genomic regions containing variants associated with sporadic late-onset AD. This is the first study of variable H3K27ac yet undertaken in AD and the largest study investigating this modification in the entorhinal cortex. In addition to identifying molecular pathways associated with AD neuropathology, we present a framework for genome-wide studies of histone modifications in complex disease, integrating our data with results obtained from genome-wide association studies as well as other epigenetic marks profiled on the same samples.

scholarly journals Genetic Interactions Explain Variance in Cingulate Amyloid Burden: An AV-45 PET Genome-Wide Association and Interaction Study in the ADNI Cohort

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jin Li ◽  
Qiushi Zhang ◽  
Feng Chen ◽  
Jingwen Yan ◽  
Sungeun Kim ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Genome Wide Association Study ◽  
Neurodegenerative Disorder ◽  
Genome Wide Association ◽  
Interaction Study ◽  
Gwas Analysis ◽  
Genome Wide ◽  
A Genome ◽  
Single Marker

Alzheimer’s disease (AD) is the most common neurodegenerative disorder. Using discrete disease status as the phenotype and computing statistics at the single marker level may not be able to address the underlying biological interactions that contribute to disease mechanism and may contribute to the issue of “missing heritability.” We performed a genome-wide association study (GWAS) and a genome-wide interaction study (GWIS) of an amyloid imaging phenotype, using the data from Alzheimer’s Disease Neuroimaging Initiative. We investigated the genetic main effects and interaction effects on cingulate amyloid-beta (Aβ) load in an effort to better understand the genetic etiology of Aβdeposition that is a widely studied AD biomarker. PLINK was used in the single marker GWAS, and INTERSNP was used to perform the two-marker GWIS, focusing only on SNPs withp≤0.01for the GWAS analysis. Age, sex, and diagnosis were used as covariates in both analyses. Correctedpvalues using the Bonferroni method were reported. The GWAS analysis revealed significant hits within or proximal toAPOE,APOC1, andTOMM40genes, which were previously implicated in AD. The GWIS analysis yielded 8 novel SNP-SNP interaction findings that warrant replication and further investigation.

Auditory Dysfunction in Alzheimer's Disease

2010 ◽  
Vol 15 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Sridhar Krishnamurti
Keyword(s):  
Alzheimer’S Disease ◽  
Older Adults ◽  
Alzheimer's Disease ◽  
Health Care ◽  
Care Setting ◽  
Neurodegenerative Disorder ◽  
Disease Process ◽  
Clinical Protocols ◽  
Speech Language Pathologist ◽  
Auditory Dysfunction

Alzheimer's disease is neurodegenerative disorder which affects a growing number of older adults every year. With an understanding of auditory dysfunction in Alzheimer's disease, the speech-language pathologist working in the health care setting can provide better service to these individuals. The pathophysiology of the disease process in Alzheimer's disease increases the likelihood of specific types of auditory deficits as opposed to others. This article will discuss the auditory deficits in Alzheimer's disease, their implications, and the value of clinical protocols for individuals with this disease.

Acetylcholinesterase Inhibitory Potential and Antioxidant Activities of Five Cultivars of Rosa Damascena Mill. From Isparta, Turkey

2020 ◽  
Vol 18 (4) ◽  
pp. 354-359
Author(s):  
Shirin Tarbiat ◽  
Azize Simay Türütoğlu ◽  
Merve Ekingen
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Free Radical ◽  
Neurodegenerative Disorder ◽  
Antioxidant Activities ◽  
Radical Scavenging ◽  
Acetylcholinesterase Activity ◽  
Rosa Damascena ◽  
Free Radical Damage

Alzheimer's disease is a neurodegenerative disorder characterized by memory loss and impairment of language. Alzheimer's disease is strongly associated with oxidative stress and impairment in the cholinergic pathway, which results in decreased levels of acetylcholine in certain areas of the brain. Hence, inhibition of acetylcholinesterase activity has been recognized as an acceptable treatment against Alzheimer's disease. Nature provides an array of bioactive compounds, which may protect against free radical damage and inhibit acetylcholinesterase activity. This study compares the in vitro antioxidant and anticholinesterase activities of hydroalcoholic extracts of five cultivars of Rosa Damascena Mill. petals (R. damascena 'Bulgarica', R. damascena 'Faik', R. damascena 'Iranica', R. damascena 'Complex-635' and R. damascena 'Complex-637') from Isparta, Turkey. The antioxidant activities of the hydroalcoholic extracts were tested for ferric ion reduction and DPPH radical scavenging activities. The anti-acetylcholinesterase activity was also evaluated. All rose cultivars showed a high potency for scavenging free radical and inhibiting acetylcholinesterase activity. There was a significant correlation between antioxidant and acetylcholinesterase inhibitory activity. Among cultivars, Complex-635 showed the highest inhibitory effect with an IC50 value of 3.92 µg/mL. Our results suggest that all these extracts may have the potential to treat Alzheimer's disease with Complex-635 showing more promise.

Repurposing Antihypertensive Drugs for the Management of Alzheimer’s Disease

2020 ◽  
Vol 27 ◽  
Author(s):  
Keng Yoon Yeong ◽  
Christine Law
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Risk Factor ◽  
Literature Review ◽  
Neurodegenerative Disorder ◽  
Antihypertensive Drugs ◽  
Future Prospects ◽  
Short Term

Alzheimer’s disease (AD) is a neurodegenerative disorder that has affected millions of people worldwide. However, currently there is no treatment to cure the disease. The AD drugs available in the market only manage the disease symptomatically and the effects are usually short-term. Thus, there is a need to look at alternatives AD therapies. Mid-life hypertension has not only been recognised as a risk factor for AD, but its relation with AD has also been well established. Thus, antihypertensives are postulated to be beneficial in managing AD. This literature review aims to shed some light on the potential of repurposing antihypertensives to treat AD, considering recent updates. Four classes of antihypertensives, as well as their potential limitations and future prospects in being utilised as AD therapeutics are discussed in this review.

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