ABSTRACT
NOTCH signaling is a key regulator involved in maintaining intestinal stem cell (ISC) homeostasis and for balancing differentiation. Using single-cell transcriptomics, we observed that OLFM4, a NOTCH target gene present in ISCs, is first expressed at 13 weeks post-conception in the developing human intestine and increases over time. This led us to hypothesize that the requirement for NOTCH signaling is acquired across human development. To test this, we established a series of epithelium-only organoids (enteroids) from different developmental stages and used γ-secretase inhibitors (dibenzazepine [DBZ] or DAPT) to functionally block NOTCH signaling. Using quantitative enteroid-forming assays, we observed a decrease in enteroid forming efficiency in response to γ-secretase inhibition as development progress. When DBZ was added to cultures and maintained during routine passaging, enteroids isolated from tissue before 20 weeks had higher recovery rates following single-cell serial passaging. Finally, bulk RNA sequencing (RNA-seq) analysis 1 day and 3 days after DBZ treatment showed major differences in the transcriptional changes between developing or adult enteroids. Collectively, these data suggest that ISC dependence on NOTCH signaling increases as the human intestine matures.
