A mitochondria-targeting glutathione fluorescent probe reveals distinct mitochondria-endoplasmic reticulum contact between disulfidptosis and ferroptosis

Mitochondria-endoplasmic reticulum (Mito-ER) contact serves as a critical regulation index of cellular stress response in various forms of cell death pathways, including Ferroptosis and Disulfidptosis. As two recently coined cell death forms, both of them are intrinsically related to the severe redox imbalance in cells, commonly featured by the decreased glutathione level. Mitochondrial glutathione (Mito-GSH) level represents a vital scale to the intracellular redox homeostasis. In this work, we reported a mitochondria-targeted fluorescent probe, PPY, that enabled GSH monitoring in live cells. The probe PPY was non-fluorescent, while upon reaction with GSH, a distinct emission peak emerged at 614 nm with high selectivity. We revealed that both Ferroptosis and Disulfidptosis induce Mito-GSH decline, reversible upon treatment with the corresponding inhibitor. Crucially, we identified a difference in organelle-level responses. Ferroptosis involved enhanced Mito-ER contact that contributed to lipid peroxide propagation, while Disulfidptosis induced minimal alterations in Mito-ER contact despite mitochondrial redox collapse. Cross-validation across multiple cell lines confirmed the universality of these findings and correlated cellular susceptibility with Mito-ER contact in Ferroptosis. This study offers new insights into the organelle-level events in Disulfidptosis and Ferroptosis, thereby filling a critical gap in the understanding of these emerging forms of cell death.

Cell imaging; Disulfidptosis; Ferroptosis; Fluorescent probe; Glutathione; Mitochondria-endoplasmic reticulum contact.