title: Inhibition of Notch signaling reduces the number of surviving Dclk1+ reserve crypt epithelial stem cells following radiation injury.
abstract: We have previously reported that doublecortin-like kinase 1 (Dclk1) is a putative intestinal stem cell (ISC) marker. In this report, we evaluated the use of Dclk1 as a marker of surviving ISCs in response to treatment with high-dose total body irradiation (TBI). Both apoptotic and mitotic Dclk1(+) cells were observed 24 h post-TBI associated with a corresponding loss of intestinal crypts observed at 84 h post-TBI. Although the Notch signaling pathway plays an important role in regulating proliferation and lineage commitment within the intestine, its role in ISC function in response to severe genotoxic injury is not yet fully understood. We employed the microcolony assay to functionally assess the effects of Notch inhibition with difluorophenacetyl-l-alanyl-S-phenylglycine t-butyl ester (DAPT) on intestinal crypt stem cell survival following severe (>8 Gy) radiation injury. Following treatment with DAPT, we observed a nearly 50% reduction in the number of surviving Dclk1(+) crypt epithelial cells at 24 h after TBI and similar reduction in the number of surviving small intestinal crypts at 84 h. These data indicate that inhibition of Notch signaling decreases ISC survival following radiation injury, suggesting that the Notch signaling pathway plays an important role in ISC-mediated crypt regeneration. These results also suggest that crypt epithelial cell Dclk1 expression can be used as one potential marker to evaluate the early survival of ISCs following severe radiation injury.
authors.affiliation: Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma;
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Qu
authors.forename: Randal
authors.initials: R
authors.lastname: May
authors.forename: Sripathi M
authors.initials: SM
authors.lastname: Sureban
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Weygant
authors.forename: Parthasarathy
authors.initials: P
authors.lastname: Chandrakesan
authors.forename: Naushad
authors.initials: N
authors.lastname: Ali
authors.forename: Linheng
authors.initials: L
authors.lastname: Li
authors.forename: Terrence
authors.initials: T
authors.lastname: Barrett
authors.forename: Courtney W
authors.initials: CW
authors.lastname: Houchen
mesh_terms: D000818:Animals; D015415:Biomarkers; D000089742:Doublecortin-Like Kinases; D004847:Epithelial Cells; D005260:Female; D005786:Gene Expression Regulation / Q000528:radiation effects*; D007413:Intestinal Mucosa / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000528:radiation effects*; D013234:Stem Cells; D014916:Whole-Body Irradiation / Q000009:adverse effects*
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D051880:Receptors, Notch; D000089742:Doublecortin-Like Kinases; C485525:Dclk1 protein, mouse; D017346:Protein Serine-Threonine Kinases
keywords: crypt survival; doublecortin-like kinase 1; radiation