Coiling of cellular protrusions around extracellular fibers

TL;DR

This study combines theoretical modeling and experimental imaging to understand how cellular protrusions coil around extracellular fibers, revealing the influence of fiber geometry on coiling behavior.

Contribution

We develop a theoretical model linking membrane mechanics to coiling and experimentally verify predictions using advanced microscopy techniques.

Findings

Protrusions coil around round fibers but not elliptical ones.

Bending and adhesion energies influence coiling orientation.

Experimental visualization confirms theoretical predictions.

Abstract

Protrusions at the leading-edge of a cell play an important role in sensing the extracellular cues, during cellular spreading and motility. Recent studies provided indications that these protrusions wrap (coil) around the extra-cellular fibers. The details of this coiling process, and the mechanisms that drive it, are not well understood. We present a combined theoretical and experimental study of the coiling of cellular protrusions on fibers of different geometry. Our theoretical model describes membrane protrusions that are produced by curved membrane proteins that recruit the protrusive forces of actin polymerization, and identifies the role of bending and adhesion energies in orienting the leading-edges of the protrusions along the azimuthal (coiling) direction. Our model predicts that the cell's leading-edge coils on round fibers, but the coiling ceases for a fiber of elliptical (flat) cross-section. These predictions are verified by 3D visualization and quantitation of coiling on suspended fibers using Dual-View light-sheet microscopy (diSPIM). Overall, we provide a theoretical framework supported by high spatiotemporal resolution experiments capable of resolving coiling of cellular protrusions around extracellular fibers of varying diameters.