NOTCH-driven oscillations control cell fate decisions during intestinal homeostasis
Intestinal homeostasis requires tight regulation of stem cell maintenance and commitment to absorptive and secretory cells, two key intestinal lineages1,2. While major signalling pathways critical for this control have been identified3, how they achieve such a tight balance in cell type composition remains unclear. Here, we uncover dynamic expression of Hes1, a direct NOTCH target3, in intestinal stem and progenitor cells, and investigate its role in vivo and in vitro. A knock-in reporter4 reveals distinct, cell-specific period lengths in Hes1 oscillations that form a gradient along the crypt-villus axis. Whereas secretory precursors oscillate at low periods, absorptive precursors oscillate at higher periods before transitioning to a differentiated state. To test the function of different oscillation periods, we innovated a microfluidic system that modulates Hes1 oscillations in organoids. We find that varying the oscillation period modulates secretory cell differentiation: While 90-min oscillations promote Paneth cells, 130-min oscillations increase formation of other secretory subtypes. Moreover, low-period oscillations support stemness and a proliferative state. Our study provides the first clear evidence that information for tissue homeostasis in the intestine is encoded in the temporal dynamics of signalling components. Overall design: To identify potential subtle changes in cell type composition upon modulation of Notch-driven oscillations, we performed bulk RNA sequencing (bulk RNAseq) after entraining oscillations to 3 different periods (90-, 130- and 170-min) for 3 different durations (24-, 48- and 72-hours).