Multi-modal transport and dispersion of organelles in narrow tubular cells

TL;DR

This paper models organelle transport in narrow cells, analyzing how active motion, diffusion, and tethering influence intracellular exploration and target capture efficiency, with implications for cellular transport optimization.

Contribution

It introduces a combined analytical and numerical model to quantify the roles of diffusion, active transport, and tethering in organelle movement within narrow tubular cells.

Findings

Diffusion and active transport equally contribute to target capture.

Tethering can enhance long-range transport under certain conditions.

The model provides testable predictions for transport regulation mechanisms.

Abstract

Intracellular components explore the cytoplasm via active motor-driven transport in conjunction with passive diffusion. We model the motion of organelles in narrow tubular cells using analytical techniques and numerical simulations to study the efficiency of different transport modes in achieving various cellular objectives. Our model describes length and time scales over which each transport mode dominates organelle motion, along with various metrics to quantify exploration of intracellular space. For organelles that search for a specific target, we obtain the average capture time for given transport parameters and show that diffusion and active motion contribute comparably to target capture in the biologically relevant regime. Because many organelles have been found to tether to microtubules when not engaged in active motion, we study the interplay between immobilization due to tethering and increased probability of active transport. We derive parameter-dependent conditions under which tethering enhances long range transport and improves the target capture time. These results shed light on the optimization of intracellular transport machinery and provide experimentally testable predictions for the effects of transport regulation mechanisms such as tethering.