A similar, albiet less severe, locomotor phenotype is seen in the dominant-negative allele of Glued (Gl1/+), confirming that disruption of Glued function in Drosophila causes age-dependent

motor deficits and reduced survival ( Figures S2A and S2B). Indeed, a reduction in lifespan is also observed after disruption of Glued function in all neurons, or specifically within motor neurons, by overexpressing either p150 protein lacking its C terminus (p150ΔC) or dynamitin (Dmn), the p50 subunit of the dynactin complex which disrupts the complex when overexpressed ( Burkhardt et al., 1997) ( Figure S2B). These Compound Library chemical structure data demonstrate that Glued function is required in motor neurons for normal locomotor function and life span. The dynactin complex regulates axonal transport in larval axons (Haghnia et al., 2007 and Pilling et al., 2006), and disruption of axonal transport may underlie the pathogenesis of dynactin-mediated neurodegenerative diseases. Loss-of-function alleles in genes that encode dynein and dynactin subunits frequently display larval “tail-flip” phenotypes and “axonal jams” that can be labeled with synaptic vesicle markers, such as antibodies against synaptotagmin (Martin et al., 1999). Surprisingly, GlG38S animals do not display either of these

phenotypes ( Figure S3A and data not shown), suggesting that axonal transport may not be severely disrupted. Because retrograde transport of Rab7(+)-signaling endosomes has been proposed to be disrupted NVP-AUY922 order in neurodegenerative diseases ( Deinhardt et al., 2006 and Perlson et al., 2010), we investigated the dynamics of endosomal

axonal transport in GlG38S animals by imaging Rab7:green fluorescent protein Thymidine kinase (GFP) in larval segmental nerves ( Figure 2A and Movies S1 and S2). Interestingly, though we see a decrease in the proportion of stationary Rab7:GFP particles in GlG38S animals ( Figure 2B), all other axonal transport measures, including flux, velocity, and processivity, are unaffected ( Figures 2C and 2D). We assayed retrograde signaling by the transforming growth factor (TGF)-beta receptor family member Wit, which is blocked in Drosophila overexpressing p150ΔC ( McCabe et al., 2003) and observed no reduction in pMad signaling in GlG38S larval motor neuron nuclei ( Figure S3B). Taken together, these data suggest that retrograde axonal transport of endosomes occurs normally in GlG38S animals. Overexpression of p150ΔC causes a reduction in synaptic bouton number at the NMJ due to presynaptic retractions (Eaton et al., 2002). In contrast, GlG38S animals have a normal number of synaptic boutons in proximal abdominal segments (segments A2 and A3) and a small but significant increase in the number of synaptic boutons in distal segments (segments A5 and A6; Figures 2E and 2F).