Redefining Signaling Pathways with an Expanding Single-Cell Toolbox

Genetically identical cells respond heterogeneously to uniform environmental stimuli. Consequently, investigating the signaling networks that control these cell responses using ‘average’ bulk cell measurements can obscure underlying mechanisms and misses information emerging from cell-to-cell variability. Here we review recent technological advances including live-cell fluorescence imaging-based approaches and microfluidic devices that enable measurements of signaling networks, dynamics, and responses in single cells. We discuss how these single-cell tools have uncovered novel mechanistic insights for canonical signaling pathways that control cell proliferation (ERK), DNA-damage responses (p53), and innate immune and stress responses (NF-κB). Future improvements in throughput and multiplexing, analytical pipelines, and in vivo applicability will all significantly expand the biological information gained from single-cell measurements of signaling pathways.

TrendsMeasuring signaling dynamics in cell populations can obscure underlying mechanisms.New tools are rapidly being developed to measure signaling at single-cell resolution.Single-cell technologies have uncovered fresh mechanistic insights for canonical signaling pathways.Future innovations will increase throughput and multiplexing of single-cell measurements.