sUPRa is a dual-color reporter for unbiased quantification of the unfolded protein response with cellular resolution

TL;DR

sUPRa is a new tool that measures the unfolded protein response in cells with high accuracy and sensitivity, revealing UPR activity in specific brain cells after sleep deprivation.

Contribution

sUPRa is a novel dual-color reporter that quantifies the global unfolded protein response with cellular resolution and improved sensitivity.

Findings

sUPRa outperforms existing reporters in sensitivity and kinetics for UPR monitoring.

sUPRa detects UPR activation in layer 2/3 pyramidal neurons of the mouse cerebral cortex after sleep deprivation.

The dual promoter design of sUPRa ensures detection of both UPR-active and inactive cells.

Abstract

The unfolded protein response (UPR) maintains proteostasis upon endoplasmic reticulum (ER) stress, and is initiated by a range of physiological and pathological processes. While there have been advances in developing fluorescent reporters for monitoring individual signaling pathways of the UPR, this approach may not capture a cell’s overall UPR activity. Here we describe a novel sensor of UPR activity, sUPRa, which is designed to report the global UPR. sUPRa displays excellent response characteristics, outperforms reporters of individual UPR pathways in terms of sensitivity and kinetics, and responds to a range of different ER stress stimuli. Furthermore, sUPRa’s dual promoter and fluorescent protein design ensures that both UPR-active and inactive cells are detected, and controls for reporter copy number. Using sUPRa, we reveal UPR activation in layer 2/3 pyramidal neurons of mouse cerebral cortex following a period of sleep deprivation. sUPRa affords new opportunities for quantifying physiological UPR activity with cellular resolution.

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