Theoretical approaches to cellular force generation and dynamics

Abstract

Living cells are extraordinarily dynamic. They can generate forces and many different types of movements. This becomes particularly striking in active processes such as cell locomotion and cell division. Inside the cell, molecules and cellular structures are transported along filaments of the cytoskeleton by motor molecules. These are highly specialized proteins which transduce the chemical energy of a fuel to generate forces and motion. In addition to transporting cargo, these motors also drive many active processes in the cell, thereby allowing cells to move on substrates and to generate converted movements during cell division.
I will discuss examples of cellular force generation and dynamics driven by motors in the cell cytoskeleton. General physical principles can help understand how complex dynamics emerges which can have important functions for the cell. Examples are spontaneous oscillations which can result from the collective action of many motors acting on elastic elements. This mechanism is for example relevant to understanding the rapid beating motion of flagella such as the one which forms the tail of sperm. The beating flagellum propels the sperm in a fluid driven by the activity of many motors inside which drive the shape changes. Spontaneous oscillations also play a key role in the amplification of mechanical vibrations by sensory cells of our ear. The nonlinear and active properties of this cellular amplifier are essential to endow the ear with its exquisite abilities to detect sound.