Motor Protein Disruption Critically Alters Organelle Trafficking and Excitation-Contraction Coupling

Trafficking of intracellular cargoes along the neuronal axonal microtubule tracks is a motor protein-dependent process. Here, we use a targeted genetic approach to knock down candidate kinesin genes involved in trafficking organelles in male and female Drosophila melanogaster Live imaging experiments revealed intracellular trafficking changes, and kinesins 1 and 3 were identified as critical regulators. Disruptions in either gene product reduce rates of axonal trafficking in motor neurons (MNs) and lead to the formation of large intracellular aggregates. Kinesin disruptions led to significant changes in neuropeptide (NP) abundance at boutons and changes in synaptic morphology. Confocal imaging revealed fewer NPs trafficking through or getting captured by synapses in kinesin knockdown experiments and a dramatic reduction in NP release at MN terminals. A profound reduction in neuromuscular transduction and excitation-contraction coupling in kinesin 1 knockdowns, but not for kinesin 3, was observed. Collectively, the targeted genetic screen of kinesin proteins revealed disruptions in kinesin 1 and 3 greatly impact intracellular axonal trafficking. Taken together, several kinesins were identified which critically regulate organelle trafficking, and genetic disruptions in key kinesins also revealed critical disruptions in cellular morphology, function, physiology, and behavior.