title: mTOR disruption causes intestinal epithelial cell defects and intestinal atrophy postinjury in mice.
abstract: Intestinal stem cells (ISCs) drive small intestinal epithelial homeostasis and regeneration. Mechanistic target of rapamycin (mTOR) regulates stem and progenitor cell metabolism and is frequently dysregulated in human disease, but its physiologic functions in the mammalian small intestinal epithelium remain poorly defined. We disrupted the genes mTOR, Rptor, Rictor, or both Rptor and Rictor in mouse ISCs, progenitors, and differentiated intestinal epithelial cells (IECs) using Villin-Cre. Mutant tissues and wild-type or heterozygous littermate controls were analyzed by histologic immunostaining, immunoblots, and proliferation assays. A total of 10 Gy irradiation was used to injure the intestinal epithelium and induce subsequent crypt regeneration. We report that mTOR supports absorptive enterocytes and secretory Paneth and goblet cell function while negatively regulating chromogranin A-positive enteroendocrine cell number. Through additional Rptor, Rictor, and Rptor/Rictor mutant mouse models, we identify mechanistic target of rapamycin complex 1 as the major IEC regulatory pathway, but mechanistic target of rapamycin complex 2 also contributes to ileal villus maintenance and goblet cell size. Homeostatic adult small intestinal crypt cell proliferation, survival, and canonical wingless-int (WNT) activity are not mTOR dependent, but Olfm4(+) ISC/progenitor population maintenance and crypt regeneration postinjury require mTOR. Overall, we conclude that mTOR regulates multiple IEC lineages and promotes stem and progenitor cell activity during intestinal epithelium repair postinjury.
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Leesa L
authors.initials: LL
authors.lastname: Sampson
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Ashley K
authors.initials: AK
authors.lastname: Davis
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Grogg
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA yi.zheng@cchmc.org.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
mesh_terms: D000818:Animals; D001284:Atrophy / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D020895:Enterocytes / Q000378:metabolism; D019858:Enteroendocrine Cells / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D020397:Goblet Cells / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019879:Paneth Cells / Q000378:metabolism; D012038:Regeneration / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D013234:Stem Cells / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases
keywords: intestinal enteroid; mouse genetics; radiation-induced injury