The human brain consists of billions of neurons that are ordered in a highly complex pattern. During development, each neuron "senses" its way through the extracellular environment by responding to different guidance cues. This process requires tight spatiotemporal regulation of these guidance signals for each neuron to reach its appropriate target position.We have identified a novel role of the microRNA (miRNA) family,
mir-251/252, in neuronal development. More specifically,
mir-251/252 controls axonal guidance events in the ventral nerve cord of Caenorhabditis elegans. Interestingly, the
mir-251/252 family is predicted to target several conserved genes known to be involved in neuronal development, such as
sax-3 (ROBO receptor),
ddr-1 (Discoidin receptor) and
ncam-1 (NCAM neural cell adhesion molecule homolog). In particular, both the seed sequence of the miRNA family and the target sequence in the 3'UTR of these genes are conserved in the invertebrates, suggesting that the mechanism through which the
mir-251/252 family regulates these genes might be conserved.