title: IGF1 stimulates crypt expansion via differential activation of 2 intestinal stem cell populations.
abstract: Insulin-like growth factor 1 (IGF1) has potent trophic effects on normal or injured intestinal epithelium, but specific effects on intestinal stem cells (ISCs) are undefined. We used Sox9-enhanced green fluorescent protein (EGFP) reporter mice that permit analyses of both actively cycling ISCs (Sox9-EGFP(Low)) and reserve/facultative ISCs (Sox9-EGFP(High)) to study IGF1 action on ISCs in normal intestine or during crypt regeneration after high-dose radiation-induced injury. We hypothesized that IGF1 differentially regulates proliferation and gene expression in actively cycling and reserve/facultative ISCs. IGF1 was delivered for 5 days using subcutaneously implanted mini-pumps in uninjured mice or after 14 Gy abdominal radiation. ISC numbers, proliferation, and transcriptome were assessed. IGF1 increased epithelial growth in nonirradiated mice and enhanced crypt regeneration after radiation. In uninjured and regenerating intestines, IGF1 increased total numbers of Sox9-EGFP(Low) ISCs and percentage of these cells in M-phase. IGF1 increased percentages of Sox9-EGFP(High) ISCs in S-phase but did not expand this population. Microarray revealed that IGF1 activated distinct gene expression signatures in the 2 Sox9-EGFP ISC populations. In vitro IGF1 enhanced enteroid formation by Sox9-EGFP(High) facultative ISCs but not Sox9-EGFP(Low) actively cycling ISCs. Our data provide new evidence that IGF1 activates 2 ISC populations via distinct regulatory pathways to promote growth of normal intestinal epithelium and crypt regeneration after irradiation.
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: Laurianne
authors.initials: L
authors.lastname: Van Landeghem
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: M Agostina
authors.initials: MA
authors.lastname: Santoro
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: Amanda T
authors.initials: AT
authors.lastname: Mah
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: Adrienne E
authors.initials: AE
authors.lastname: Krebs
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Dehmer
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: Kirk K
authors.initials: KK
authors.lastname: McNaughton
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Helmrath
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA.
authors.forename: Scott T
authors.initials: ST
authors.lastname: Magness
authors.affiliation: *Department of Cell Biology and Physiology, Department of Nutrition, Department of Surgery, and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; and University of North Carolina/North Carolina State Biomedical Engineering, Chapel Hill, North Carolina, USA empk@med.unc.edu.
authors.forename: P Kay
authors.initials: PK
authors.lastname: Lund
mesh_terms: D053687:Adult Stem Cells / Q000145:classification* / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002453:Cell Cycle; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology / Q000502:physiology*; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D007421:Intestine, Small / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D039902:Multipotent Stem Cells / Q000145:classification / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011833:Radiation Injuries, Experimental / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D017526:Receptor, IGF Type 1 / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012038:Regeneration / Q000187:drug effects / Q000502:physiology; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse; C485184:enhanced green fluorescent protein; C519530:insulin-like growth factor-1, mouse; D049452:Green Fluorescent Proteins; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1
keywords: actively cycling ISCs; facultative/reserve ISCs; irradiation; tissue regeneration
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