WDR79/TCAB1 plays a conserved role in the control of locomotion and ameliorates phenotypic defects in SMA models

- WDR79/TCAB1 is required for locomotion in both D. melanogaster and C. elegans.
- The Smn transcript and protein product are downregulated in WDR79 mutant flies.
- Smn overexpression rescues the WDR79 loss-of-function phenotype in flies.
- WDR79 overexpression rescues the fly and worm phenotypes induced by Smn depletion.

SMN (Survival Motor Neuron) deficiency is the predominant cause of spinal muscular atrophy (SMA), a severe neurodegenerative disorder that can lead to progressive paralysis and death. Although SMN is required in every cell for proper RNA metabolism, the reason why its loss is especially critical in the motor system is still unclear. SMA genetic models have been employed to identify several modifiers that can ameliorate the deficits induced by SMN depletion. Here we focus on WDR79/TCAB1, a protein important for the biogenesis of several RNA species that has been shown to physically interact with SMN in human cells. We show that WDR79 depletion results in locomotion defects in both Drosophila and Caenorhabditis elegans similar to those elicited by SMN depletion. Consistent with this observation, we find that SMN overexpression rescues the WDR79 loss-of-function phenotype in flies. Most importantly, we also found that WDR79 overexpression ameliorates the locomotion defects induced by SMN depletion in both flies and worms. Our results collectively suggest that WDR79 and SMN play evolutionarily conserved cooperative functions in the nervous system and suggest that WDR79/TCAB1 may have the potential to modify SMA pathogenesis.