Modeling Notch Activity and Lineage Decisions Using Intestinal Organoids.

Organoid cultures have been developed to model intestinal stem cell (ISC) function in self-renewal and differentiation. Upon differentiation, the first fate decision for ISC and early progenitors to make is between secretory (Paneth cell, goblet cell, enteroendocrine cell, or tuft cell) and absorptive (enterocyte and M cell) lineages. Using genetic and pharmacological approaches, in vivo studies in the past decade have revealed that Notch signaling functions as a binary switch for the secretory vs. absorptive lineage decision in adult intestine. Recent breakthroughs in organoid-based assays enable real-time observation of smaller-scale and higher-throughput experiments in vitro, which have begun contributing to new understandings of mechanistic principles underlying intestinal differentiation. In this chapter, we summarize the in vivo and in vitro tools for modulating Notch signaling and assess its impact on intestinal cell fate. We also provide example protocols of how to use intestinal organoids as functional assays to study Notch activity in intestinal lineage decisions.