title: Vascular Endothelial Growth Factor (VEGF) Bioavailability Regulates Angiogenesis and Intestinal Stem and Progenitor Cell Proliferation during Postnatal Small Intestinal Development.
abstract: BACKGROUND
  Vascular endothelial growth factor (VEGF) is a highly conserved, master regulatory molecule required for endothelial cell proliferation, organization, migration and branching morphogenesis. Podocoryne carnea and drosophila, which lack endothelial cells and a vascular system, express VEGF homologs, indicating potential roles beyond angiogenesis and vasculogenesis. The role of VEGF in the development and homeostasis of the postnatal small intestine is unknown. We hypothesized regulating VEGF bioavailability in the postnatal small intestine would exhibit effects beyond the vasculature and influence epithelial cell stem/progenitor populations.
  
  
  METHODS
  VEGF mutant mice were created that overexpressed VEGF in the brush border of epithelium via the villin promotor following doxycycline treatment. To decrease VEGF bioavailability, sFlt-1 mutant mice were generated that overexpressed the soluble VEGF receptor sFlt-1 upon doxycycline administration in the intestinal epithelium. Mice were analyzed after 21 days of doxycycline administration.
  
  
  RESULTS
  Increased VEGF expression was confirmed by RT-qPCR and ELISA in the intestine of the VEGF mutants compared to littermates. The VEGF mutant duodenum demonstrated increased angiogenesis and vascular leak as compared to littermate controls. The VEGF mutant duodenum revealed taller villi and increased Ki-67-positive cells in the transit-amplifying zone with reduced Lgr5 expression. The duodenum of sFlt-1 mutants revealed shorter villi and longer crypts with reduced proliferation in the transit-amplifying zone, reduced expression of Dll1, Bmp4 and VE-cadherin, and increased expression of Sox9 and EphB2.
  
  
  CONCLUSIONS
  Manipulating VEGF bioavailability leads to profound effects on not only the intestinal vasculature, but epithelial stem and progenitor cells in the intestinal crypt. Elucidation of the crosstalk between VEGF signaling in the vasculature, mesenchyme and epithelial stem/progenitor cell populations may direct future cell therapies for intestinal dysfunction or disease.
authors.affiliation: Developmental Biology and Regenerative Medicine Program, The Saban Research Institute at Children's Hospital Los Angeles, Los Angeles, California, United States of America.|Department of Surgery, Division of Pediatric Surgery, Children's Hospital Los Angeles, Los Angeles, California, United States of America.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Schlieve
authors.affiliation: Developmental Biology and Regenerative Medicine Program, The Saban Research Institute at Children's Hospital Los Angeles, Los Angeles, California, United States of America.|Department of Biology, California State University San Bernardino, San Bernardino, California, United States of America.
authors.forename: Salvador Garcia
authors.initials: SG
authors.lastname: Mojica
authors.affiliation: Developmental Biology and Regenerative Medicine Program, The Saban Research Institute at Children's Hospital Los Angeles, Los Angeles, California, United States of America.|Department of Surgery, Division of Pediatric Surgery, Children's Hospital Los Angeles, Los Angeles, California, United States of America.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Holoyda
authors.affiliation: Developmental Biology and Regenerative Medicine Program, The Saban Research Institute at Children's Hospital Los Angeles, Los Angeles, California, United States of America.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Hou
authors.affiliation: Developmental Biology and Regenerative Medicine Program, The Saban Research Institute at Children's Hospital Los Angeles, Los Angeles, California, United States of America.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Fowler
authors.affiliation: Developmental Biology and Regenerative Medicine Program, The Saban Research Institute at Children's Hospital Los Angeles, Los Angeles, California, United States of America.|Department of Surgery, Division of Pediatric Surgery, Children's Hospital Los Angeles, Los Angeles, California, United States of America.
authors.forename: Tracy C
authors.initials: TC
authors.lastname: Grikscheit
mesh_terms: D058739:Aberrant Crypt Foci / Q000235:genetics; D000818:Animals; D000833:Animals, Suckling; D019559:Capillary Leak Syndrome / Q000235:genetics; D002455:Cell Division; D002478:Cells, Cultured; D004318:Doxycycline / Q000494:pharmacology; D004386:Duodenum / Q000098:blood supply / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D005786:Gene Expression Regulation; D007091:Image Processing, Computer-Assisted; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D008871:Microvilli / Q000648:ultrastructure; D018919:Neovascularization, Physiologic / Q000235:genetics; D009940:Organoids; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000096:biosynthesis / Q000235:genetics; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000096:biosynthesis / Q000235:genetics
chemical_list: D011993:Recombinant Fusion Proteins; D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C501163:Flt1 protein, mouse; D040281:Vascular Endothelial Growth Factor Receptor-1; D004318:Doxycycline