Fluorescent indicators for visualizing dynamic contact between cells and between processes originating from a single cell.

Cells continuously communicate through dynamic cell-cell contacts. Tools for visualizing these dynamic interactions in living cells are essential to the study of fundamental biological processes in multicellular organisms. Here, we present two fluorescent indicators, Gachapin and Gachapin-C, for visualizing dynamic cell-cell contact. Gachapin visualizes not only static but also dynamic contacts. Multiplexed imaging combining green Gachapin with spectrally distinct indicators allows simultaneous monitoring of contact dynamics, cytoskeletal assembly, and intracellular signaling during cell movement. Furthermore, the formation and disruption of contacts between neuronal processes can be visualized. Gachapin-C enables contact visualization with a single indicator component, whereas previous indicators required two components introduced into different cells. This feature allows Gachapin-C to monitor contacts between processes originating from a single cell. We expect Gachapin and Gachapin-C will serve as useful tools for providing deeper insights into cell-cell contact-mediated processes.