Profiling of differentially expressed circular RNAs in peripheral blood mononuclear cells from Alzheimer's disease patients.

Expression of circular RNA (circRNA), a class of noncoding RNAs that regulates gene expression, is altered in Alzheimer's disease. This study profiled differentially expressed circRNAs in peripheral blood mononuclear cells (PBMCs) from five patients with Alzheimer's disease compared to healthy controls using circRNA microarrays. We identified a total of 4060 differentially expressed circRNAs (1990 upregulated and 2070 downregulated) in Alzheimer's disease patients. Among these circRNAs, 10 randomly selected circRNAs were verified using qRT-PCR. The top 10 upregulated and downregulated circRNAs were used to predict their target miRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that these differentially expressed circRNAs were strongly associated with inflammation, metabolism, and immune responses, which are all risk factors for Alzheimer's disease. The circRNA-miRNA-mRNA network was most involved in the MAPK, mTOR, AMPK, and WNT signaling pathways in Alzheimer's disease. In conclusion, the current study demonstrated the importance of circRNAs in Alzheimer's disease development. Future studies will evaluate some of these circRNAs as biomarkers for early disease detection and to develop therapeutic strategies to clinically control Alzheimer's disease progression.