Regulatory Role of MicroRNAs in Brain Development and Function.

MicroRNAs (miRNAs) are small non-coding RNA molecules of about 20-22 nucleotides. After their posttranscriptional maturation, miRNAs are loaded into the ribonucleoprotein complex RISC and modulate gene expression by binding to the 3' untranslated region of their target mRNAs through base-pairing, which in turn triggers mRNA degradation or translational inhibition. There is mounting evidence that miRNAs regulate various biological processes, including cell proliferation, differentiation, and apoptosis. Several studies have shown that miRNAs play an important role in neurogenesis and brain development.This review discusses recent progress on understanding the implication of precisely regulated miRNA expression in normal brain development and function. In addition, it reports known cases of dysregulation of miRNA expression and function implicated in the pathogenesis of neurodevelopmental disorders, craniofacial dysmorphic syndromes, neurodegenerative diseases, and psychiatric disorders. Current knowledge regarding the role of miRNAs in the brain in conjunction with the complex interplay between genetic and epigenetic factors are discussed.