Figure 8.

mTOR differentially regulates adult distal small intestinal epithelium during homeostasis and regeneration. A) During homeostasis, mTOR promotes absorptive and secretory lineage IEC terminal maturation, but not their specification. One exception is the EEC lineage, which is expanded upon mTOR disruption. ISC and progenitor activities are largely maintained in the mTOR^ΔIEC model. B) During injury-induced regeneration, mTOR becomes critical for ISC and progenitor activity, and mTOR loss leads to intestinal epithelial atrophy. Olfm4⁺ ISC marker expression is reduced, suggesting an ISC self-renewal defect. TA, transit-amplifying cell. Red X’s mark where mTOR is necessary to promote further IEC lineage development.