Exploring the interplay between zinc-induced protein dyshomeostasis and mitochondrial dysfunction using viscosity-sensitive sensor.

Mitochondria are crucial sites for protein quality control within cells. When mitochondrial stress is triggered by protein misfolding, it can accelerate abnormal protein aggregation, potentially inducing various diseases. This study developed a cascade-responsive sensor, named AggHX, to monitor the microenvironment of protein aggregation induced by zinc (II) ions and the accompanying mitochondrial dysfunction. The AggHX consists of two key components: (1) A Zn²⁺ recognition group for triggering a fluorescent enhance response, and (2) a near-infrared BODIPY scaffold that detects viscosity changes in cell aggregation via HaloTag. This sensor's mechanism of action is elucidated through photochemical and biochemical characterizations. To further investigate the relationship between protein aggregation and mitochondrial homeostasis, we employ fluorescence lifetime imaging microscopy to assess viscosity changes in protein aggregates under intracellular Zn²⁺ stress. This research provides insights into the dynamic behavior and spatial distribution of protein aggregates and mitochondria, contributing to a deeper understanding of their physiological roles in cellular processes and potential implications in disease pathology.