Robustness of bidirectional microtubule network self-organization

Abstract

Robustness of biological systems is crucial for their survival, however, for many systems its origin is an open question. Here we analyze one sub-cellular level system, the microtubule cytoskeleton. Microtubules self-organize into a network, along which cellular components are delivered to their biologically relevant locations. While individual microtubule are highly dynamic with their dynamics depends on the organism environment and genetics, network sensitivity to this dynamics would result in pathologies. Combining mathematical modelling with genetic manipulations in Drosophila, we show that the microtubule self-organization indeed does not depend on dynamics of individual microtubules, and thus is robust on the tissue level. We demonstrate the origin of this robustness via a mathematical model, suggesting this being a generic mechanism.

The walkoff effect: cargo distribution implies motor type in bidirectional microtubule bundles

“…The 1d MT bundle consists of stochastic 1d MTs anchored at cell walls. Each MT is modelled by a finite length Markov chain ( Fig.1a) to account for the dynamic instability (following [58][59][60]). Here the MT of length n dimers can be in either polymerizing, depolymerizing, or the minus-end state (P n , D n , or D 0 ), where the maximum MT length is the length of the bundle.…”

“…To validate the predicted roles of kinesins and dyneins in transport on MT networks with mixed directionality we turned to epithelial cells in the Drosophila embryonic epidermis. There, the apical MTs grow from the sites of cell-cell adhesion on the cell boundaries and are restricted to a thin 1 µm layer below the cell apical surface [26,38,60]. To investigate the directions of MT growth, we examined live embryos expressing the GFPtagged End Binding protein 1 (EB1-GFP) at the stage 15 of the embryonic development ( Fig.…”