title: GATA4 regulates epithelial cell proliferation to control intestinal growth and development in mice.
abstract: OBJECTIVE
  The embryonic small intestinal epithelium is highly proliferative, and although much is known about mechanisms regulating proliferation in the adult intestine, the mechanisms controlling epithelial cell proliferation in the developing intestine are less clear. GATA4, a transcription factor that regulates proliferation in other developing tissues, is first expressed early in the developing gut in midgut endoderm. GATA4 function within midgut endoderm and the early intestinal epithelium has not been investigated.
  
  
  METHODS
  Using Sonic Hedgehog Cre to eliminate GATA4 in the midgut endoderm of mouse embryos, we determined the impact of loss of GATA4 on intestinal development, including epithelial cell proliferation, between E9.5-E18.5.
  
  
  RESULTS
  We found that intestinal length and width were decreased in GATA4 mutants compared with controls. GATA4-deficient intestinal epithelium contained fewer cells, and epithelial girth was decreased. We further observed a decreased proportion of proliferating cells at E10.5 and E11.5 in GATA4 mutants. We demonstrated that GATA4 binds to chromatin containing GATA4 consensus binding sites withinCyclin D2(Ccnd2),Cyclin dependent kinase 6 (Cdk6), andFrizzled 5 (Fzd5).Moreover, Ccnd2, Cdk6, and Fzd5 transcripts were reduced at E11.5 in GATA4 mutant tissue. Villus morphogenesis was delayed, and villus structure was abnormal in GATA4 mutant intestine.
  
  
  CONCLUSIONS
  Our data identify GATA4 as an essential regulator of early intestinal epithelial cell proliferation. We propose that GATA4 controls proliferation in part by directly regulating transcription of cell cycle mediators. Our data further suggest that GATA4 affects proliferation through transcriptional regulation ofFzd5, perhaps by influencing the response of the epithelium to WNT signaling.
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin, 53226, USA.
authors.forename: Bridget M
authors.initials: BM
authors.lastname: Kohlnhofer
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin, 53226, USA.
authors.forename: Cayla A
authors.initials: CA
authors.lastname: Thompson
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin, 53226, USA.
authors.forename: Emily M
authors.initials: EM
authors.lastname: Walker
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin, 53226, USA.
authors.forename: Michele A
authors.initials: MA
authors.lastname: Battle
keywords: WNT signaling; transcriptional regulation; villus morphogenesis