Functional Proteomics and Biological Screening of Protein Misfolding Under ER Stress Conditions in a Neuroblastoma Cell Model.

Endoplasmic reticulum (ER) stress represents a critical pathophysiological condition that plays a central role in the development of various human diseases, including protein misfolding diseases. While the small molecule Vx-445 (Elexacaftor) exhibits robust cellular bioactivity, its cryptic intracellular targets and off-label mechanisms of action remain poorly defined. This study investigates the cytoprotective efficacy and molecular targets of Vx-445 in Thapsigargin-induced ER stress in a neuronal cell model. Integrating biochemical assays, gene expression proteomics, and label-free functional proteomics, we demonstrate that Vx-445 significantly mitigates oxidative stress by reducing intracellular levels of reactive oxygen species, restores calcium homeostasis to baseline levels, and prevents apoptosis by inhibiting cytochrome c release. These phenotypic modifications correlated with changes in proteomic expression and were validated by Drug Affinity Responsive Target Stability (DARTS) analysis to map restored cellular pathways and identify potential protein interaction partners. Together, these findings uncover alternative molecular targets for Vx-445, providing a mechanistic basis for drug repurposing strategies in endoplasmic reticulum stress-related diseases.