Cell-to-cell variation sets a tissue-rheology-dependent bound on collective gradient sensing

TL;DR

This paper demonstrates that cell-to-cell variation significantly influences collective gradient sensing, with fluid clusters achieving higher accuracy by leveraging cell motion noise to improve rheological properties.

Contribution

It introduces a theoretical framework linking cell-to-cell variation, cluster rheology, and gradient sensing accuracy, highlighting the role of fluidity in collective chemotaxis.

Findings

Cluster bias can be dominated by cell-to-cell variation rather than ligand-receptor binding.

Fluid clusters can outperform solid ones in gradient sensing accuracy.

Increasing cell motion noise can enhance collective sensing by improving cluster fluidity.

Abstract

When a single cell senses a chemical gradient and chemotaxes, stochastic receptor-ligand binding can be a fundamental limit to the cell's accuracy. For clusters of cells responding to gradients, however, there is a critical difference: even genetically identical cells have differing responses to chemical signals. With theory and simulation, we show collective chemotaxis is limited by cell-to-cell variation in signaling. We find that when different cells cooperate the resulting bias can be much larger than the effects of ligand-receptor binding. Specifically, when a strongly-responding cell is at one end of a cell cluster, cluster motion is biased toward that cell. These errors are mitigated if clusters average measurements over times long enough for cells to rearrange. In consequence, fluid clusters are better able to sense gradients: we derive a link between cluster accuracy, cell-to-cell variation, and the cluster rheology. Because of this connection, increasing the noisiness of individual cell motion can actually increase the collective accuracy of a cluster by improving fluidity.