Acid-Resistant and Viscosity-Sensitive Proteome Aggregation Sensor To Visualize Cellular Aggrephagy in Live Cells and Clinical Samples.

Aggrephagy in cells is defined as the degradation of intracellular aggregated proteins via the macroautophagy process. This process sequesters protein aggregates into autolysosomes, which bear characteristic viscous and acidic microenvironments. Limited protein aggregation sensors are environmentally compatible with the cellular aggrephagy process. Here, we report an acid-resistant and viscosity-sensitive proteome aggregation sensor to detect cellular aggrephagy in stressed cells and clinical samples. This sensor fluoresces upon selectively and ubiquitously binding to different aggregated proteins. Importantly, unlike other reported protein aggregation sensors, our probe offers unique acid-resistant fluorescence inside aggregated proteins, enabling its application in the acidic autolysosome microenvironment. In live cells under various stressed conditions, the optimal probe (A6) successfully detects aggregated proteome in autolysosomes, as validated by colocalization with a lysosomal tracker. Additionally, we demonstrate that the sensor can detect proteome aggregation in heat-stressed clinical tissue samples biopsied from cancer patients undergoing thermal perfusion treatment. Together, the reported acid-resistant and viscosity-sensitive protein aggregation sensor facilitates the detection of cellular aggrephagy by chemically matching its microenvironmental characteristics.