Measurement of intercellular transfer to signaling endosomes

Cell-cell communication is essential for an abundance of physiological processes. As such, various mechanisms have evolved to regulate and ensure proper cell-to-cell signaling. Recently, a novel mechanism of cell communication has emerged which involves the physical transfer of proteins, lipids, and nucleic acids between cells. Following this process termed intercellular transfer (ICT), the transferred molecules can signal within recipient cells by entering the endosomal system and trafficking to signaling endosomes. Signaling endosomes can modulate signal localization within the cell as well as the specificity of, and cross talk between, signaling pathways. As such, ICT into signaling endosomes has the potential to modify the signaling profile of the recipient cell. In this chapter, we describe the different methods of ICT as well as how transfer to signaling endosomes can be visualized and quantified.