A role for a rat homolog of staufen in the transport of RNA to neuronal dendrites

RNAs are present in dendrites and may be used for local protein synthesis i n response to synaptic activity. To begin to understand dendritic RNA targe ting, we cloned a rat homolog of staufen, a Drosophila gene that participat es in mRNA targeting during development. In hippocampal neurons, rat staufe n protein displays a microtubule-dependent somatodendritic distribution pat tern that overlaps with dendritic RNAs. To determine whether r-staufen is r equired for dendritic RNA targeting, we constructed a mutant version contai ning the RNA binding domains (stau-RBD) but lacking the C-terminal portion potentially involved in dendritic targeting. Stau-RBD expression was restri cted to the cell bodies and proximal dendrites. Expression of stau-RBD sign ificantly decreased, while overexpression of wild-type r-staufen increased, the amount of dendritic mRNA. Taken together, these results suggest that t he rat staufen protein plays an important role in the delivery of RNA to de ndrites.