Experimental and theoretical model for the origin of coiling of cellular protrusions around fibers

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 extracellular fibers. However, the physics 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 fibers with circular cross-section (above some critical radius), but the coiling ceases for flattened fibers of highly elliptical 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 experiments, which explains the physical origin of the coiling phenomenon.

Ultra-thin and ultra-porous nanofiber networks as a basement-membrane mimic

“…63,73 These findings have been validated to match various in vivo bahaviors. [74][75][76] We integrated our nanofiber membrane into a PDMS microfluidic model; however, absorption and adsorption of molecules by PDMS makes it unfavorable for drug transport studies. 77 Since our nanofibers are polystyrene, an entirely plastic device could be designed and assembled for commercial use.…”

Forceful patterning: theoretical principles of mechanochemical pattern formation

“…For example, curvature‐mediated pattern formation plays a role in the formation of cellular protrusions, such as those involved in cell migration or myelination‐like coiling. There, proteins such as curved BAR proteins couple to membrane shape and interact with the actin cytoskeleton, producing dynamic patterns and protrusions on the cell surface (Simunovic et al , 2015; Carman & Dominguez, 2018; Gov, 2018; Wu et al , 2018; Begemann et al , 2019; Sadhu et al , 2021, 2023; Ravid et al , 2023).…”