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A Study of Small RNAs from Cerebral Neocortex of Pathology-Verified Alzheimer’s Disease, Dementia with Lewy Bodies, Hippocampal Sclerosis, Frontotemporal Lobar Dementia, and Non-Demented Human Controls

ABSTRACT: MicroRNAs (miRNAs) are small (20-22 nucleotides) regulatory non-coding RNAs that strongly influence gene expression. Most prior studies addressing the role of miRNAs in neurodegenerative diseases (NDs) have focused on individual controls (n = 2), AD (n = 5), dementia with Lewy bodies (n = 4), hippocampal sclerosis of aging (n = 4), and frontotemporal lobar dementia (FTLD) (n = 5) cases, together accounting for the most prevalent ND subtypes. All cases had short postmortem intervals, relatively high-quality RNA, and state-of-the-art neuropathological diagnoses. The resulting data (over 113 million reads in total, averaging 5.6 million reads per sample) and secondary expression analyses constitute an unprecedented look into the human cerebral cortical miRNome at single nucleotide resolution. While we find no apparent changes in isomiR or miRNA editing patterns in correlation with ND pathology, our results validate and extend previous miRNA profiling studies with regard to quantitative changes in NDs. In agreement with this idea, we provide independent cohort validation for changes in miR-132 expression levels in AD (n = 8) and FTLD (n = 14) cases when compared to controls (n = 8). The identification of common and ND-specific putative novel brain miRNAs and/or short-hairpin molecules is also presented. The challenge now is to better understand the impact of these and other alterations on neuronal gene expression networks and neuropathologies.

ORGANISM(S): Homo sapiens

PROVIDER: GSE46131 | GEO | 2013/04/18

SECONDARY ACCESSION(S): PRJNA197328

REPOSITORIES: GEO

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Project description:Dementia with Lewy bodies (DLB) is the second most common cause of degenerative dementia after Alzheimer’s disease (AD) and presents several overlapping pathological and clinical features with both AD and Parkinson’s disease (PD). Consequently, only one in three DLB cases is diagnosed correctly. Platelets are anucleate cells containing cellular structures and molecules, such as microRNA (miRNA), the analysis of which provides biomarkers for several disorders. In this cross-sectional study, we profiled the whole platelet miRNA transcriptome from 7 DLB patients and 7 healthy controls using Next-Generation Sequencing (NGS) and found 22 differentially expressed miRNAs. These miRNAs were further validated with miRCURY LNA miRNA Custom PCR panels in three consecutive validation studies carried out from 2017-2019 with a total of 162 individuals including DLB (n=59), AD (n=28), and PD patients (n=24), and healthy controls (n=51). As a result, three different groups of miRNAs were identified as related to DLB, AD and PD, all in comparison with controls. Additionally, our results demonstrated a significant down-regulation of hsa-miR-26b-5p and hsa-miR-150-5p in DLB compared to PD; and a signature composed of seven miRNAs that had lower expression in DLB compared to AD. The predictive diagnostic value of this bio-signature for the differentiation of DLB from AD was assessed calculating the corresponding ROC curve, which yielded an area under the curve of 1.00. Predictive analyses using specialized software (miRTarbase, miRGate) were performed for the disease-specific miRNAs to identify target genes and corresponding pathways. Three disease-specific clusters of pathways and biological processes were identified as a result of platelet-miRNA deregulation. In DLB, pathways related to gene expression and small RNA metabolism; in AD, pathways related to stress response and RNA stress granules; and in PD pathways related to protein phosphorylation, and protein metabolism and degradation were identified. In conclusion, we describe the identification of a novel, highly specific and sensitive platelet-associated miRNA-based bio-signature, which permits us to distinguish between DLB and AD.

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A Study of Small RNAs from Cerebral Neocortex of Pathology-Verified Alzheimer’s Disease, Dementia with Lewy Bodies, Hippocampal Sclerosis, Frontotemporal Lobar Dementia, and Non-Demented Human Controls

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