title: Krüppel-like factor 5 mediates transmissible murine colonic hyperplasia caused by Citrobacter rodentium infection.
abstract: OBJECTIVE
  Krüppel-like factor 5 (KLF5) is a transcription factor that is highly expressed in proliferating crypt cells of the intestinal epithelium. KLF5 has a pro-proliferative effect in vitro and is induced by mitogenic and stress stimuli. To determine whether KLF5 is involved in mediating proliferative responses to intestinal stressors in vivo, we examined its function in a mouse model of transmissible murine colonic hyperplasia triggered by colonization of the mouse colon by the bacteria Citrobacter rodentium.
  
  
  METHODS
  Heterozygous Klf5 knockout (Klf5(+/-)) mice were generated from embryonic stem cells carrying an insertional disruption of the Klf5 gene. Klf5(+/-) mice or wild-type (WT) littermates were infected with C rodentium by oral gavage. At various time points postinfection, mice were killed and distal colons were harvested. Colonic crypt heights were determined morphometrically from sections stained with H&E. Frozen tissues were stained by immunofluorescence using antibodies against Klf5 and the proliferation marker, Ki67, to determine Klf5 expression and numbers of proliferating cells per crypt.
  
  
  RESULTS
  Infection of WT mice with C rodentium resulted in a 2-fold increase in colonic crypt heights at 14 days postinfection and was accompanied by a 1.7-fold increase in Klf5 expression. Infection of Klf5(+/-) mice showed an attenuated induction of Klf5 expression, and hyperproliferative responses to C rodentium were reduced in the Klf5(+/-) animals as compared with WT littermates.
  
  
  CONCLUSIONS
  Our study shows that Klf5 is a key mediator of crypt cell proliferation in the colon in response to pathogenic bacterial infection.
authors.affiliation: Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Beth B
authors.initials: BB
authors.lastname: McConnell
authors.forename: Jan-Michael A
authors.initials: JM
authors.lastname: Klapproth
authors.forename: Maiko
authors.initials: M
authors.lastname: Sasaki
authors.forename: Mandayam O
authors.initials: MO
authors.lastname: Nandan
authors.forename: Vincent W
authors.initials: VW
authors.lastname: Yang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation; D044082:Citrobacter rodentium / Q000302:isolation & purification* / Q000472:pathogenicity; D003092:Colitis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D003106:Colon / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D004195:Disease Models, Animal; D004756:Enterobacteriaceae Infections / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D015870:Gene Expression; D005838:Genotype; D006965:Hyperplasia / Q000209:etiology / Q000235:genetics / Q000473:pathology; D007413:Intestinal Mucosa / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D051741:Kruppel-Like Transcription Factors / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012313:RNA / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C118391:Klf5 protein, mouse; D051741:Kruppel-Like Transcription Factors; D012313:RNA