A gene signal amplifier platform for monitoring the unfolded protein response

Gene expression in mammalian cells results from coordinated protein-driven processes guided by diverse mechanisms of regulation, including protein–protein interactions, protein localization, DNA modifications and chromatin rearrangement. Regulation of gene expression is particularly important in stress-response pathways. To address the need to monitor chromosomal gene expression generating a readily detectable signal output that recapitulates gene expression dynamics, we developed a gene signal amplifier platform that links transcriptional and post-translational regulation of a fluorescent output to the expression of a chromosomal target gene. We generated a multiplex reporter system for monitoring markers of the unfolded protein response, a complex signal transduction pathway that remodels gene expression in response to proteotoxic stress in the endoplasmic reticulum. By recapitulating the transcriptional and translational control mechanisms underlying the expression of a target gene with high sensitivity, this platform provides a technology for monitoring gene expression with superior sensitivity and dynamic resolution. Engineering of a synthetic circuit that couples transcriptional and protein turnover regulation to a fluorescent protein readout enables sensitive monitoring and amplification of gene expression signals from the unfolded protein response pathway.