Local regulation of neuronal microtubules and synaptic cargo

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In neurons, microtubule polymers support axonal transport by molecular motors to deliver cargo to synapses. There is a growing understanding that the properties of microtubules polymers, such as their dynamics or post-translational modifications, can influence motor motility. There is also ample evidence that in neurons, MT properties are not uniform across axons and dendrites. However, it is still unclear what are the mechanisms that locally regulate neuronal microtubules, and how the resulting changes influence cargo transport. This proposal aims to understand how microtubule polymer length, abundance and distribution are locally regulated, and how this affects cargo delivery to synapses. It will do so by studying the role of an atypical kinesin, VAB-8/KIF26, which we recently identified as a local regulator of microtubule organization and synapses in C. elegans. The work proposed here will determine (1) how Wnt signaling directs the activity of VAB-8/KIF26 to a specific axonal sub-domain, (2) how VAB-8/KIF26 regulates microtubule length and abundance, and (3) how this regulation influences the delivery of cargo to presynaptic sites. Answering these questions will increase our basic understanding of local regulation of neuronal microtubules and its influence on axonal transport. The evolutionary conservation of VAB-8/KIF26 and Wnt signaling and the cardinal role of MTs in neuronal development, maintenance and dysfunction underscore the importance of this fundamental knowledge.