Project description:Human post-mortem brain samples (middle temporal gyrus) from Alzheimer's disease (AD) and control individuals were processed for simultaneous coding and non-coding RNA-Seq analysis using a novel RNA-Seq protocol. These data were then analyzed for differential expression.
Project description:Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive deterioration of cognitive function. Evidence suggests a role for epigenetic regulation, in particular the cytosine modifications 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC,) in AD. 5hmC is highly enriched in the nervous system and displays neurodevelopment and age-related changes. To determine the role of 5hmC in AD, we performed genome-wide analyses of 5hmC in DNA from prefrontal cortex of post-mortem AD as well as RNA-Seq to correlate changes in methylation status with transcriptional changes. We also utilized the existing AD fly model to further test the functional significance of these epigenetically altered loci. We identified 325 genes containing differentially hydroxymethylated loci (DhMLs) in both the discovery and replication datasets, and these are enriched for pathways involved in neuron projection development and neurogenesis. Of the 325 genes identified, 140 also showed changes in gene expression by RNA-Seq. Proteins encoded by genes identified in the current analysis form direct protein-protein interactions with AD-associated genes, expanding the network of genes implicated in AD. Furthermore, we identified AD-associated single nucleotide polymorphisms (SNPs) located within or near DhMLs, suggesting that these SNPs may identify regions of epigenetic gene regulation that play a role in AD pathogenesis. Finally using the existing AD fly model we showed that some of these genes could modulate the toxicity associated with AD. Our data implicate neuron projection development and neurogenesis pathways as potential targets in AD. These results indicate that incorporating epigenomic and transcriptomic data with GWAS data can expand the known network of genes involved in disease pathogenesis. Combination of epigenome profiling and Drosophila model enables us to identify the epigenetic modifiers of Alzheimer's disease. University of Kentucky Alzheimer's Disease Research Center (3 control, 3 Alzheimer's) and Emory University Alzheimer's Disease Research Center (2 control, 2 Alzheimer's)
Project description:N6-methyladenosine (m6A) is an abundant internal RNA modification that can impact gene expression at both post-transcriptional and transcriptional levels. However, the landscapes and functions of m6A in human brains and neurodegenerative diseases, including Alzheimer's disease (AD), are under-explored. Here, we examined RNA m6A methylome using total RNA-seq and meRIP-seq in middle frontal cortex of post-mortem brains from individuals with or without AD, which revealed m6A alteration on both mRNAs and various noncoding RNAs. Notably, many promoter-antisense RNAs (paRNAs) displayed cell-type-specific expression and changes in AD, including one produced adjacent to MAPT that encodes the Tau protein. MAPT-paRNA is highly expressed in neurons, and m6A positively controls its expression. In iPSC-derived human excitatory neurons, MAPT-paRNA does not impact the nearby MAPT mRNA, but instead promotes expression of hundreds of neuronal and synaptic genes, and is protective against excitotoxicity. Analysis of single nuclei RNA-DNA interactome in human brains supports that brain paRNAs interact with both cis- and trans-chromosomal target genes to impact their transcription. These data reveal landscapes and functions of noncoding RNAs and m6A in brain gene regulation and AD pathogenesis.