Polymorphisms affecting miRNA regulation: a new level of genetic variation affecting disorders and diseases of the human CNS

Network and Pathway-Based Analysis of Single-Nucleotide Polymorphism of miRNA in Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is a complex disease with its pathogenetic mechanism still unclear. Single-nucleotide polymorphisms (SNPs) of miRNA (miRSNPs) are SNPs located on miRNA genes or target sites of miRNAs, which have been proved to be associated with neuropsychic disease development by interfering with miRNA-mediated regulatory function. In this study, we integrated TLE-related risk genes and risk pathways multi-dimensionally based on public data resources. Furthermore, we systematically screened candidate functional miRSNPs for TLE and constructed a TLE-associated pathway-based miRSNP switching network, which included 92 miRNAs that target 12 TLE risk pathways. Moreover, we dissected thoroughly the correlation between 5 risk genes of 4 risk pathways and TLE development. Additionally, the biological function of several candidate miRSNPs were validated by luciferase reporter assay. In silico approach facilitates to select potential "miRSNP-miRNA-risk gene-pathway" axis for experimental validation, which provided new insights into the mechanism of miRSNPs as potential genetic risk factors of TLE.

MicroRNA Alterations in the Brain and Body Fluids of Humans and Animal Prion Disease Models: Current Status and Perspectives

Prion diseases are transmissible progressive neurodegenerative conditions characterized by rapid neuronal loss accompanied by a heterogeneous neuropathology, including spongiform degeneration, gliosis and protein aggregation. The pathogenic mechanisms and the origins of prion diseases remain unclear on the molecular level. Even though neurodegenerative diseases, including prion diseases, represent distinct entities, their pathogenesis shares a number of features including disturbed protein homeostasis, an overload of protein clearance pathways, the aggregation of pathological altered proteins, and the dysfunction and/or loss of specific neuronal populations. Recently, direct links have been established between neurodegenerative diseases and miRNA dysregulated patterns. miRNAs are a class of small non-coding RNAs involved in the fundamental post-transcriptional regulation of gene expression. Studies of miRNA alterations in the brain and body fluids in human prion diseases provide important insights into potential miRNA-associated disease mechanisms and biomarker candidates. miRNA alterations in prion disease models represent a unique tool to investigate the cause-consequence relationships of miRNA dysregulation in prion disease pathology, and to evaluate the use of miRNAs in diagnosis as biomarkers. Here, we provide an overview of studies on miRNA alterations in human prion diseases and relevant disease models, in relation to pertinent studies on other neurodegenerative diseases.

A functional SNP catalog of overlapping miRNA-binding sites in genes implicated in prion disease and other neurodegenerative disorders

The involvement of SNPs in miRNA target sites remains poorly investigated in neurodegenerative disease. In addition to associations with disease risk, such genetic variations can also provide novel insight into mechanistic pathways that may be responsible for disease etiology and/or pathobiology. To identify SNPs associated specifically with degenerating neurons, we restricted our analysis to genes that are dysregulated in CA1 hippocampal neurons of mice during early, preclinical phase of Prion disease. The 125 genes chosen are also implicated in other numerous degenerative and neurological diseases and disorders and are therefore likely to be of fundamental importance. We predicted those SNPs that could increase, decrease, or have neutral effects on miRNA binding. This group of genes was more likely to possess DNA variants than were genes chosen at random. Furthermore, many of the SNPs are common within the human population, and could contribute to the growing awareness that miRNAs and associated SNPs could account for detrimental neurological states. Interestingly, SNPs that overlapped miRNA-binding sites in the 3'-UTR of GABA-receptor subunit coding genes were particularly enriched. Moreover, we demonstrated that SNP rs9291296 would strengthen miR-26a-5p binding to a highly conserved site in the 3'-UTR of gamma-aminobutyric acid receptor subunit alpha-4.