MicroRNA Implications in Neurodegenerative Disorders

The importance of non-coding RNAs that regulate cellular processes has become evident in the recent past. The most prominent among this class of RNAs are microRNAs (miRs) that are 20-22-nucleotide long single stranded RNAs. miRs are transcribed from the genome as longer transcripts called primary miRs that are processed sequentially by RNAse III enzymes DROSHA and Dicer to generate the mature form. In the cytoplasm, miRs recruit a protein complex called the RNA-induced silencing complex (RISC) and mediates downregulation of translation from target mRNAs. miRs are expressed in a tissue, cell-type and developmental stage specific manner. Aberrant expression of miRs therefore contributes to disease pathology as a consequence of dysregulation of target protein levels. In this chapter we review the discovery, biogenesis, mechanism of action of miRs and their role in neuronal function and dysfunction with emphasis on HIV-associated neurocognitive disorders.