How torque on formins is relaxed strongly affects cellular swirling

Area of Science:

• Cellular dynamics and biophysics
• Cytoskeletal organization and mechanics
• Chirality in biological systems

Background:

• Chirality is a fundamental property of biological systems across various scales.
• Formins play a crucial role in regulating actin dynamics, influencing cellular structures and movements.
• Understanding torque relaxation mechanisms in formins is key to explaining cellular chiral swirling.

Purpose of the Study:

• To investigate the impact of different torque relaxation strategies of formins on cellular chiral swirling.
• To elucidate the relationship between formin torque relaxation and the directionality of cellular rotation.
• To identify efficient torque relaxation mechanisms that promote significant cellular swirling.

Main Methods:

• Adaptation of a previously developed rotational clutch-filament model.
• Simulation and analysis of three distinct types of formin torque relaxation.
• Comparison of model predictions with experimental observations of cellular swirling.

Main Results:

• Periodic positive/negative rotation during capping results in negligible cell rotation.
• Randomly regulated rotation leads to minor counterclockwise or clockwise cell rotation.
• Transient loosening of formin contact with the membrane or actin filament induces prominent cellular rotation.

Conclusions:

• The mechanism of torque relaxation in formins significantly dictates the extent and direction of cellular swirling.
• Transient detachment of formin from its anchor or the actin filament is an efficient strategy for inducing substantial cellular rotation.
• This study provides insights into the biophysical basis of chiral swirling in cells.