Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Monday Speaker Abstracts

Rotation, Twisting, and Pulling: The Rich Dynamics of Filopodia

Natascha Leijnse, Lene B. Oddershede,

Poul M. Bendix

University of Copenhagen, Copenhagen, Denmark.

Filopodia allow the cell to sense and interact with their surroundings. Rigidity sensing and

application of piconewton traction forces are key functions that filopodia employ to sense and

regulate cellular interactions. However, despite their ubiquitous presence in most cells, their

different modes of movement remains poorly characterized. Recently, we found surprising

evidence for a new pulling mechanism originating from twisting of the actin within the

filopodium [1,2]. This mechanism can only be present in filopodia which contain a rotating actin

bundle. By imaging the actin, we clearly observed rotation and retrograde flow of small buckles

which formed in filopodia from HEK293 cells. The movement of these buckles was found to be

coupled to the pulling force exerted by the filopodium in a manner which indicated that torsional

twist was accumulated in the actin bundle. Our results provide the first clear evidence of rotation

of the actin within filopodia a key property which might facilitate both interaction and

exploration of the cell’s 3D environment.

1. Leijnse N, Oddershede LB, Bendix PM. An updated look at actin within filopodia. A Review,

Cytoskeleton 2015, 72, 71-79.

2. Leijnse N, Oddershede LB, & Bendix PM. Helical buckling of actin inside filopodia generates

traction. PNAS 2015, 112(1), 136-141.