Distinct cell shapes determine accurate chemotaxis

Abstract

The behaviour of an organism often reflects a strategy for coping with its environment. Such behaviour in higher organisms can often be reduced to a few stereotyped modes of movement due to physiological limitations, but finding such modes in amoeboid cells is more difficult as they lack these constraints. Here, we examine cell shape and movement in starved Dictyostelium amoebae during migration toward a chemoattractant in a microfluidic chamber. We show that the incredible variety in amoeboid shape across a population can be reduced to a few modes of variation. Interestingly, cells use distinct modes depending on the applied chemical gradient, with specific cell shapes associated with shallow, difficult-to-sense gradients. Modelling and drug treatment reveals that these behaviours are intrinsically linked with accurate sensing at the physical limit. Since similar behaviours are observed in a diverse range of cell types, we propose that cell shape and behaviour are conserved traits.

How cells explore shape space: A quantitative statistical perspective of cellular morphogenesis

“…Other groups have reported that migrating fish keratocytes and Dictyostelium cells also exist in a low‐dimensional shape space. Despite their different origins, many cell lines adopt shapes that are strikingly similar.…”

Chemotaxis of a model organism: progress with Dictyostelium

“…The seemingly endless variety of cell shape seen in chemotaxis can be reasonably well described mathematically by just three principal components, representing cell elongation, cell polarisation and pseudopod splitting or bending [6 ]. Cells adopt characteristic shapes according to the strength (signal/noise) of the chemotactic gradient: in strong gradients they tend to be wedge shaped and move quickly, whereas in weak gradients they typically alternate between pseudopod splitting and cell elongation.…”

Local sampling paints a global picture: Local concentration measurements sense direction in complex chemical gradients

“…Early observations in Dictyostelium and neutrophils suggested that small membrane protrusions, called filopodia, preferentially form towards the external gradient [48,49]. Stochastic cell-shape changes in response to gradients may thus act as an additional layer regulating the dynamics of the polarised assembly [50,51]. The increased local membrane area increases the local receptor concentration, and thus likely enhances polarised assembly recruitment locally.…”