Regensburg 2016 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 58: Cytoskeletal Filaments

BP 58.5: Vortrag

Donnerstag, 10. März 2016, 10:45–11:00, H44

Axonal microtubule bundle polarity is maintained by mechanically mediated depolymerization of ill-oriented microtubules — •Maximilian Jakobs and Kristian Franze — University of Cambridge, UK

The microtubule (MT) bundles found in neuronal axons are highly polar with around 90% of all MTs pointing with their +end away from the cell body. Disruption of this polarity is thought to be involved in a variety of neurodegenerative diseases. Although the MT array polarity has been discovered more than 30 years ago, its origin is still poorly understood. We here tracked growing MT +ends in dissociated primary neurons to look for correlations between bundle polarity, MT growth and transport velocities, and MT growth lifetimes. Even though the +ends moved in the anterograde (away from the cell body) and retrograde (towards the cell body) direction with similar velocities, the fraction of velocities above 15μm/min was larger in the retrograde direction, implying that active transport drives -end out MTs back into the cell body. Additionally, MTs stopped growing more frequently when pointing with their +end towards the cell body than vice versa. This behaviour might be explained by an increased drag force acting on retrogradely growing MTs, which originates from an anterogradely directed viscous flow within the axon. This flow acts as a mechanical barrier for retrogradely growing MTs, facilitating their depolymerization and thus keeping the MT array polar. Understanding the mechanism that polarises the axonal MT array might yield new approaches towards preventing neuronal degeneration during disease.