title: Fibroblast growth factor receptor-3 is expressed in undifferentiated intestinal epithelial cells during murine crypt morphogenesis.
abstract: Prior studies have demonstrated that fibroblast growth factor receptor-3 (FGFR-3) regulates proliferation of undifferentiated intestinal epithelial cells in vitro. However, the function(s) of FGFR-3-mediated signaling during intestinal development and epithelial differentiation in vivo remain unknown. The goal of this study was to define the temporal, regional, and cell-specific patterns of FGFR-3 expression and its ligands during normal intestinal ontogeny and epithelial regeneration. Both the IIIb and IIIc isoforms of FGFR-3 mRNA, which result from differential splicing of the FGFR-3 primary transcript, were detected in mouse small intestine as early as embryonic day 16. FGFR-3 levels peaked in the small intestine from 7 to 21 days after birth and decreased thereafter to reach the low levels observed in adult mice. FGFR-3 IIIb and IIIc mRNA levels were highest in the duodenum and proximal jejunum with lower levels of both seen in the distal jejunum, ileum, and colon. FGFR-3 was expressed in a subset of proliferating undifferentiated crypt epithelial cells located in the intervillous epithelium and in the lower half of nascently forming crypts but not in differentiated epithelial cell types. FGFR-3 IIIb was the dominant isoform expressed in both small intestinal and colonic crypts. Expression of FGF1, FGF2, and FGF9, known ligands of FGFR-3, paralleled patterns of FGFR-3 expression during gut development. These data suggest that signaling through FGFR-3 plays a role in regulating morphogenic events involved in formation of intestinal crypts and/or the fate of epithelial stem cells.
authors.affiliation: Digestive Health Center of Excellence, University of Virginia, Charlottesville, Virginia 22908, USA.
authors.forename: Alda
authors.initials: A
authors.lastname: Vidrich
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Buzan
authors.forename: Chibuzo
authors.initials: C
authors.lastname: Ilo
authors.forename: Leigh
authors.initials: L
authors.lastname: Bradley
authors.forename: Kirstin
authors.initials: K
authors.lastname: Skaar
authors.forename: Steven M
authors.initials: SM
authors.lastname: Cohn
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002454:Cell Differentiation; D002455:Cell Division; D004848:Epithelium / Q000196:embryology; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000196:embryology; D007422:Intestines / Q000196:embryology*; D008024:Ligands; D051379:Mice; D009024:Morphogenesis; D020033:Protein Isoforms; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D051498:Receptor, Fibroblast Growth Factor, Type 3; D017468:Receptors, Fibroblast Growth Factor / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D008024:Ligands; D020033:Protein Isoforms; D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; C496366:Fgfr3 protein, mouse; D011505:Protein-Tyrosine Kinases; D051498:Receptor, Fibroblast Growth Factor, Type 3; D001973:Bromodeoxyuridine