Spreading through the cell via non-canonical modes of transport*

Cells rely on a variety of mechanisms for delivering particles ranging from small molecules to micron-sized organelles to their various destinations. We use physical modeling coupled with live-cell imaging data from collaborating groups to explore the interplay of different transport modes in distributing particles through the complex intracellular environment. This talk will focus on two examples of multi-modal transport: combining motor-driven motion, diffusion, and fluid flow for efficient dispersion of particles within the cell.

Organelle hitchhiking is a non-canonical form of transport, which relies on a cargo organelle attaching to a motor-driven ''carrier'' with the aid of linker proteins. We quantify the effect of physical parameters on hitchhiking efficiency, demonstrating an insensititivy to linker density and a substantial benefit from tethering of cargo organelles to microtubule tracks. Our model is parameterized and validated against dynamic imaging data in fungal hyphae.

In addition, we investigate the role of advective transport for proteins and ions within the endoplasmic reticulum (ER). Capitalizing on recent experimental evidence of contraction-driven uncoordinated flow within ER tubules, we show that rapid flow combine with mobile calcium-binding buffer proteins can substantially enhance the distribution of calcium ions within the active network structure of the ER.