Measuring Endocytosis and Endosomal Uptake at Single Cell Resolution

Endocytosis impacts many cell biological functions, including in embryonic stem cells (ESCs). It has been shown that endocytosis is necessary for adequate FGF-signaling within the preimplantation ESC to post-implantation epiblast (EpiLC) pluripotency continuum and is required for proper levels of ERK activation. Quantitative methods at single cell resolution are needed to study endocytosis as well as its regulation and roles in these transitioning populations. The methods in this chapter provide an easily adaptable, multiplexable platform to monitor and quantify endosomal uptake at single cell resolution in live cells following receptor-mediated and non-receptor-mediated endocytosis, including nonspecific mechanisms such as pinocytosis.