Modelling the Role of Intrinsic Electric Fields in Microtubules as an Additional Control Mechanism of Bi-directional Intracellular Transport

Abstract

Active transport is essential for cellular function, while impaired transport has been linked to diseases such as neuronal degeneration. Much long distance transport in cells uses opposite polarity molecular motors of the kinesin and dynein families to move cargos along microtubules. It is clear that many types of cargo are moved by both sets of motors, and frequently in a reverse direction. The general question of how the direction of transport is regulated is still open. The mechanism of the cell's differential control of diverse cargos within the same cytoplasmic background is still unclear as is the answer to the question how endosomes and mitochondria move to different locations within the same cell. To answer these questions we postulate the existence of a local signaling mechanism used by the cell to specifically control different cargos. In particular, we propose an additional physical mechanism that works through the use of constant and alternating intrinsic (endogenous) electric fields as a means of controlling the speed and direction of microtubule-based transport. A specific model is proposed and analyzed in this paper. The model involves the rotational degrees of freedom of the C-termini of tubulin, their interactions and the coupling between elastic and dielectric degrees of freedom. Viscosity of the solution is also included and the resultant equation of motion is found as a nonlinear elliptic equation with dissipation. A particular analytical solution of this equation is obtained in the form of a kink whose properties are analyzed. It is concluded that this solution can be modulated by the presence of electric fields and hence may correspond to the observed behavior of motor protein transport along microtubules.

Modified extended tanh-function method and nonlinear dynamics of microtubules

“…These solitons will turn on kinesin motors in order to attach to the same MTs and to carry mitochondria towards MT plus-ends which are close to cell membrane. It might be useful to mention that some similar ideas were elaborated earlier [13,14].…”

Discrete and solitons-like modes as nonlinear dynamics in microtubules based on an improved longitudinal u -model

“…More interestingly, all these various features underlying the nonlinear dynamics of MTs can be relevant to many biological processes such as cell growth and division for which MTs disassemble and re-assemble 7,11,53,54 , chemical energy transition in the process of hydrolysis of GTP nucleotides and microtubule motor proteins transport such as kinesins and dyneins 12,50-52 , excitations and inhibition of biomembranes and neurons 7,13,55 , intracellular transport of biological materials including cytoplasmic transport and transport of both proteins and organelles 18,27,56 , cellular movements including and separating chromosomes during mitosis and meiosis [57][58][59] , respiratory infection 60 , dynamic information processing including processing, propagation, storage and transduction, of biological information in MTs 2,7, [13][14][15][16] .…”

The Cytoskeleton as a Nanoscale Information Processor: Electrical Properties and an Actin-Microtubule Network Model

“…It has also been proposed that microtubules possess pyroelectric properties (i.e., the ability to generate an intrinsic electric field due to temperature changes in the medium [53]). The intrinsic electric field produced by microtubules may further regulate microtubule functions, such as transport and neural plasticity.…”