Modeling the effect of a microtubule swirl on fast axonal transport

Many neurodegenerative diseases, such as Alzheimerʹs disease, are linked to swellings occurring in the long arms of neurons. Many scientists believe that these swellings result from traffic jams caused by the failure of the intracellular machinery responsible for fast axonal transport; such traffic jam can plug an axon and prevent the sufficient amount of organelles to be delivered toward the synapse of the axon. One possible mechanistic explanation of the formation of traffic jams in axons induced by overexpression of tau protein is based on the hypothesis that the traffic jam is caused not by the failure of molecular motors to transport organelles along individual microtubules but rather by the disruption of the microtubule system in an axon, by the formation of a swirl of disoriented microtubules at a certain location in the axon. This paper develops a model for investigating the effect of a microtubule swirl, as well as the effect of reversing polarity of a microtubule segment in the swirl region, on fast axonal transport.