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Abstract
A neuron is a specialized cell that transmits nerve impulses. Dendrites of a neuron receive signals from other cells or the environment and transmit them to the soma. Dendrites branch out to cast a wide receptive field and establish neural connections that govern behavior, learning, and memory; therefore regulation of dendritic branching is essential for sensory reception. It is important to understand how these different processes form because many neurological diseases show atypical dendritic and axonal phenotypes (Kulkarni and Firestein 2012). RNA-binding proteins (RBPs) have become of particular interest as many RBPs have recently been implicated in the process of dendrite formation. RBPs are known to be important in post-transcriptional regulation of gene expression. A previous study showed that an RBP named Shep regulates dendrite development in Drosophila (Mapes et al., 2010). To determine if Shep is evolutionarily conserved in its role in dendrite development we tested its C. elegans ortholog (sup-26) for a role in dendrite development in the multidendritic PVD sensory neuron. Loss of sup-26 activity results in a significant reduction of terminal dendrites in the PVD neuron. Furthermore, time course analysis of dendrite development revealed sup-26 mutants have a dendrite maintenance defect. sup-26 is expressed in many cells including the PVD neuron and SUP-26 protein localizes to the cytoplasm, consistent with its role as a potential translational regulator. Dendrite defects are partially rescued by PVD-specific expression of the SUP-26::GFP fusion protein, which suggests that SUP-26 functions cell-autonomously within the PVD to regulate dendrites. We hypothesize that sup-26 acts as a translational repressor of mRNAs that are important for dendrite regulation. Because sup-26/shep functions in dendrite development in fly and worm, and has three human homologs expressed in the brain, it suggests that sup-26 orthologs may be important in the development of dendrites in humans as well.