Speaker
Description
The coordination of cellular activities relies on the close positioning of intracellular organelles at membrane contact sites (MCSs), which has been found altered in several diseases. However, MCS study has been hampered by the lack of tools allowing to track membrane proximity with high spatial and temporal resolution. To address this limitation, we developed reversible fluorescent probes that can detect MCSs between various intracellular organelles. These new reporters are based on splitFAST, a chemogenetic system originally designed to visualize dynamic protein-protein interactions in the green, red, or far-red spectrum. We found that the probe targeting ER-mitochondria (ER-mit) contact sites promptly detects transient interactions between these organelles with high resolution, permitting us to monitor how MCSs change in response to different cellular treatments. Interestingly, we observed that some ER-mit contacts are highly dynamic and undergo fusion and fission events. Additionally, by expressing the ER-mit reporter, we confirmed an increase in ER-mit MCSs in astrocytes, neurons, and fibroblasts derived from Alzheimer’s disease mouse models and human patients. Finally, by endowing these probes with calcium-sensing domains, we created a new set of reporters named PRINCESS (PRobe for INterorganelle Ca2+-Exchange Sites based on SplitFAST), allowing to simultaneously visualize MCSs and measure local Ca2+ dynamics. These probes will be helpful to better highlight the role of MCS dynamics in health and disease.
[Michela Rossini, Paloma García Casas, Linnea Påvénius, Mezida Saeed, Hjalmar Brismar, Maria Ankarcrona, Arnaud Gautier, Paola Pizzo, Riccardo Filadi]
