Deciphering the Function and Regulation of microRNAs in Alzheimer's Disease and Parkinson's Disease

MicroRNAs (miRNAs) are single stranded, noncoding RNA molecules that are encoded by eukaryotic nuclear DNA. miRNAs function through imperfect base-pairing with complementary sequences of target mRNA molecules, which is typically via the cleavage of target mRNA with transcriptional repression or translational degradation. An increasing number of studies identified dysregulation of miRNAs in neurodegenerative disease and suggest that alterations in the miRNA regulatory pathway could contribute to the disease pathogenesis. However, molecular mechanisms underlying the pathological implications of dysregulated miRNA expression and regulation of the key genes that are involved in neurodegenerative diseases remain largely unknown. Here, we review the evidence for the functional role of dysregulated miRNAs involved in disease pathogenesis, as well as how miRNAs govern neuronal functions either upstream or downstream of target genes that are disease pathogenic factors. Furthermore, we review the cellular feedback regulation between miRNAs and target genes in neurodegenerative diseases, with a focus on Alzheimer's disease and Parkinson's disease