Fluorescence and Lifetime Imaging of Endoplasmic Reticulum Polarity Change During Ferroptosis

As a new form of regulated cell death, ferroptosis is closely related to various diseases. Tracing ferroptosis related biological behavior is helpful to better understand this process and its related biology. Considering that ferroptosis is featured with remarkable lipid peroxidation which can easily change the membranes' compositions and structures, it is potential to detect intracellular environmental changes for direct assessment of ferroptosis. In view of the close relationship between endoplasmic reticulum (ER) and ferroptosis, we designed an ER-targeted and polarity-sensitive fluorescent probe SBD-CH, which has superior photostability and can respond to polarity with high selectivity without the affection of viscosity. SBD-CH can monitor the trend of ER polarity during ferroptosis by confocal laser scanning microscopy (CLSM), and analyze the distribution of polarity in ferroptosis by fluorescence lifetime imaging microscopy (FLIM). During Erastin induced ferroptosis, the polarity of ER in HT-1080 cells increased and the polarity distribution in ER was more dispersed. Our work provides an effective strategy for evaluating the process of ferroptosis by monitoring the changes of ER polarity. An endoplasmic reticulum (ER)-targeted and polarity-sensitive fluorescent probe, SBD-CH, was developed. By combining confocal laser scanning microscopy with fluorescence lifetime imaging microscopy, it revealed an increased and more dispersed ER polarity during ferroptosis. The common ferroptosis inhibitor Fer-1 could only partially reduce the polarity of ER, but did not restore the dispersion loss of ER membrane. image