A synthetic gene circuit for imaging-free detection of dynamic cell signaling

Abstract

Cells employ intracellular signaling pathways to sense and respond to changes in their external environment. In recent years, live-cell biosensors have revealed complex pulsatile dynamics in many pathways, but studies of these signaling dynamics are limited by the necessity of live-cell imaging at high spatiotemporal resolution1. Here, we describe an approach to infer pulsatile signaling dynamics from just a single measurement in fixed cells using a pulse-detecting gene circuit. We computationally screened for circuit with pulse detecting capability, revealing an incoherent feedforward topology that robustly performs this computation. We then implemented the motif experimentally for the Erk signaling pathway using a single engineered transcription factor and fluorescent protein reporter. Our recorder of Erk activity dynamics (READer) responds sensitively to both spontaneous and stimulus-driven Erk pulses. READer circuits thus open the door to permanently labeling transient, dynamic cell populations to elucidate the mechanistic underpinnings and biological consequences of signaling dynamics.