Associate Professor Pól Martin Bendix, Niels Bohr Institute, University of Copenhagen

Active generation of twist in filopodia

Filopodia, dynamic extensions rich in actin filaments found on the surfaces of eukaryotic cells, play a crucial role in environmental exploration, mechanical force generation, and chemical signaling. In our study, we demonstrate that filopodia navigate their three-dimensional extracellular surroundings through a combination of growth, retraction, axial twisting, and buckling. Notably, the actin core within filopodia exhibits a twisting or spinning motion, a phenomenon observed across a spectrum of cell types, from early developmental stages to highly specialized tissue cells. Non-equilibrium physical modeling of actin and myosin confirm that twist is an emergent phenomenon of active filaments confined in a narrow channel which is supported by measured traction forces and helical buckles that can be ascribed to accumulation of sufficient twist. Consequently, our results lead us to the conclusion that the actin shaft's activity-induced twisting represents a universal mechanism that underlies the fundamental functions of filopodia.

I will also elaborate on other examples to illustrate how we use optical bio-manipulation and thermoplasmonics in different biological systems.

References:

1. Nano Letters, 23, 3377-3384 (2023). Thermoplasmonic Vesicle Fusion Reveals Membrane Phase Segregation of Influenza Spike Proteins. G. Moreno-Pescador, M.R. Arastoo, V.T. Ruhoff, S. Chiantia, R. Daniels, P.M. Bendix.
2. Nature Communications, 13, 1, 1636 (2022). Filopodia rotate and coil by actively generating twist in their actin shaft. N. Leijnse, Y. F. Barooji, M. R. Arastoo, S. L. Sønder, B. Verhagen, L. Wullkopf, J. T. Erler, S. Semsey, J. Nylandsted, L. B. Oddershede, A. Doostmohammadi, P. M. Bendix.