MOLECULAR BIOLOGY: miRNAs in Neurodegeneration

The human genome sequencing effort has taught us that it takes relatively few genes to build a human being. Complexity arises from the combination of these building blocks into genetic programs that are finely tuned in space and time during cell and tissue differentiation. A major part of this regulation is performed by microRNAs (miRNAs), small RNA molecules encoded by the genome that are not translated into proteins; rather, they control the expression of genes. Deregulation of miRNA function has been implicated in human diseases including cancer and heart disease (1, 2). On page 1220 of this issue, Kim et al. (3) suggest that miRNAs are essential for maintaining dopaminergic neurons in the brain, and thus could play a role in the pathogenesis of Parkinson's disease.