Chalcone derivatives as dual-sensitive fluorescent probe for protein aggregation investigation

Abstract

Protein homeostasis is of great importance for cellular viability. However, environmental factors such as drug treatment, pathogen infection etc. may cause compromised proteostasis, which further lead to protein misfolding or aggregation. Herein, based on rational design, a toolbox of chalcone derivatives was developed to probe the whole process of protein aggregation. The chalcone derivatives disclosed here were dual-sensitive probes that exhibited viscosity-dependent fluorescence intensity enhancement and polarity-dependent emission wavelength variability. Structural modulation identified that both polarity and viscosity sensitivity of chalcone derivatives were tunable via electron density regulation and π-rich bridge extension way. Furthermore, upon binding to protein of interest (POI), the optimized probe demonstrated “stepwise turn-on” fluorescence performances and varying wavelength in different aggregating stages that allowed for the investigation of microenvironment change of the whole process of protein aggregation. Finally, the optimized probe was utilized to investigate the aggregated proteome in live cells upon proteasome inhibitor stressing. Overall, a rational approach was disclosed here to develop new probes with controllable polarity and viscosity sensitivity, tunable spectral coverage for efficient investigation of protein aggregation in live cell.