mir-57 Influences Posterior Motor Neuron Axon Morphology in Caenorhabditis elegans.

Organization and specification of the nervous system start in the embryo and are largely controlled by a cluster of transcription factors known as HOX genes, which control body patterning and morphogenesis at the transcriptional level. However, this entire process requires the influence of multiple pathways, including cell signalling, genomic and post-genomic pathways. These include the Wnt (wingless) pathway, which controls neuronal development and polarity, and the small miRNA pathway, which regulates genes post-transcriptionally. In this study, we investigated mir-57, the homolog of human miR-10 in Caenorhabditis elegans and its role in influencing motor neuron function. mir-57 is expressed posteriorly throughout development and enriched in motor neurons. Absence of mir-57 results in decreased movement and abnormal axonal projections of posterior motor neurons. Moreover, the Wnt pathway genes cam-1 and mom-5 are mir-57 targets and show elevated expression at the post-transcriptional level in mir-57 deletion mutants. Taken together this study suggests that mir-57 influences Wnt receptor expression to maintain posterior motor neuron axon morphology.