Rac1 signaling nanoclusters

The plasma membrane of eukaryotic cells is a highly organized surface where hundreds of incoming signals are transduced to the intracellular space.

 

How cells encode faithfully this myriad of signals is a fundamental question. Using single molecule imaging in polarized cells, we recently showed that Rac1, a critical membrane-bound protein involved in the regulation of cytoskeletal dynamics, forms small aggregates together with other regulating proteins.

 

These  supramolecular assemblies, called nanoclusters, are the quantal units of signaling. By increasing the local concentration, nanoclusters set thresholds for downstream signaling and ensure the fidelity of information transduction. Thanks to cell patterning and optogenetics activations, we further showed that Rac1 nanoclusters are distributed as spatial gradients matching the patterns of Rac1 activity. We propose that cells can encode positional information through distributed signaling quanta, hereby ensuring spatial fidelity.