SensEnhance: A Genetic Circuit for Converting Endogenous Mammalian Gene Signals Into High‐Dynamic‐Range Genetic Readouts

Integrating synthetic gene circuits with endogenous mammalian gene expression programs enables genetic readouts of physiologically relevant cellular states. However, the performance of these readouts is often constrained by sensing promoters with low maximal output, modest fold changes, and high basal activity. Here, we use mathematical modeling and analysis to devise SensEnhance, a generalizable genetic circuit architecture that converts leaky, low-dynamic-range promoter signals into tightly controlled, high-dynamic-range outputs. SensEnhance combines sequestration-mediated suppression below a tunable response threshold with feedback-supported amplification above it. We implement SensEnhance through split intein-mediated protein trans-splicing and experimentally validate its predicted input-output behavior and threshold tunability. We apply SensEnhance to a YAP/TAZ-responsive mechanosensing promoter and stably integrate the circuit into NIH/3T3 fibroblasts, increasing output fold change between soft and stiff tissue-like hydrogels from 2.6-fold in the promoter-only configuration to over 20-fold using SensEnhance. When coupled to a STAT3-responsive promoter showing a 2.5-fold change in response to IL-6, SensEnhance increases this fold change to 14-fold, improving cytokine sensing and supporting its generic applicability across signaling pathways. These results establish SensEnhance as a modular strategy for improving the dynamic range and tunability of mammalian genetic biosensors.