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McConnell BB, Klapproth JMA, Sasaki M, Nandan MO, Yang VW. Krüppel-like factor 5 mediates transmissible murine colonic hyperplasia caused by Citrobacter rodentium infection. Gastroenterology 2008; 134:1007-16. [PMID: 18395082 PMCID: PMC2336106 DOI: 10.1053/j.gastro.2008.01.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2007] [Accepted: 01/04/2008] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS 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. CONCLUSION Our study shows that Klf5 is a key mediator of crypt cell proliferation in the colon in response to pathogenic bacterial infection.
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Affiliation(s)
- Beth B. McConnell
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Jan-Michael A. Klapproth
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Maiko Sasaki
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Mandayam O. Nandan
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Vincent W. Yang
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia,*Address correspondence to: Vincent W. Yang, M.D., Ph.D., 201 Whitehead Biomedical Research Building, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, Tel: (404) 712-5638; Fax: (404) 727-5767;
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202
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A core Klf circuitry regulates self-renewal of embryonic stem cells. Nat Cell Biol 2008; 10:353-60. [PMID: 18264089 DOI: 10.1038/ncb1698] [Citation(s) in RCA: 565] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Accepted: 01/02/2008] [Indexed: 02/07/2023]
Abstract
Embryonic stem (ES) cells are unique in their ability to self-renew indefinitely and maintain pluripotency. These properties require transcription factors that specify the gene expression programme of ES cells. It has been possible to reverse the highly differentiated state of somatic cells back to a pluripotent state with a combination of four transcription factors: Klf4 is one of the reprogramming factors required, in conjunction with Oct4, Sox2 and c-Myc. Maintenance of self-renewal and pluripotency of ES cells requires Oct4, Sox2 and c-Myc, but Klf4 is dispensable. Here, we show that Krüppel-like factors are required for the self-renewal of ES cells. Simultaneous depletion of Klf2, Klf4 and Klf5 lead to ES cell differentiation. Chromatin immunoprecipitation coupled to microarray assay reveals that these Klf proteins share many common targets of Nanog, suggesting a close functional relationship between these factors. Expression analysis after triple RNA interference (RNAi) of the Klfs shows that they regulate key pluripotency genes, such as Nanog. Taken together, our study provides new insight into how the core Klf circuitry integrates into the Nanog transcriptional network to specify gene expression that is unique to ES cells.
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Nandan MO, McConnell BB, Ghaleb AM, Bialkowska AB, Sheng H, Shao J, Babbin BA, Robine S, Yang VW. Krüppel-like factor 5 mediates cellular transformation during oncogenic KRAS-induced intestinal tumorigenesis. Gastroenterology 2008; 134:120-30. [PMID: 18054006 PMCID: PMC2194652 DOI: 10.1053/j.gastro.2007.10.023] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Accepted: 09/10/2007] [Indexed: 12/30/2022]
Abstract
BACKGROUND & AIMS Krüppel-like factor 5 (KLF5) is a zinc finger-transcription factor that regulates cell proliferation. Oncogenic KRAS mutations are commonly found in colorectal cancers. We aimed to determine whether KLF5 mediates KRAS functions during intestinal tumorigenesis. METHODS The effects of KLF5 on proliferation and transformation were examined in IEC-6 intestinal epithelial cells stably transfected with inducible KRAS(V12G). KLF5 expression was examined in intestinal tumors derived from transgenic mice expressing KRAS(V12G) under villin promoter and in human colorectal cancers with mutated KRAS. RESULTS Induction of KRAS(V12G) in IEC-6 cells resulted in increased expression of KLF5, accompanied by increased rates of proliferation and anchorage-independent growth. Inhibition of KLF5 expression by mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) inhibitors or KLF5-specific small interfering RNA reduced proliferation and anchorage-independent growth despite KRAS(V12G) induction. Human colorectal cancer cell lines with mutated KRAS contained high levels of KLF5 and reduction of KLF5 by MEK inhibitors or KLF5 small interfering RNA also led to reduced proliferation and transformation. In vivo, both intestinal tumors derived from mice transgenic for villin-KRAS(V12G) and human primary colorectal cancers with mutated KRAS contained high levels of KLF5 and increased staining of the proliferative marker Ki67. CONCLUSIONS Elevated levels of KLF5 protein are strongly correlated with activating KRAS mutations in intestinal tumors in vitro and in vivo. Inhibition of KLF5 expression in tumor cells resulted in significantly reduced rates of proliferation and transforming activities. We conclude that KLF5 is an important mediator of oncogenic KRAS transforming functions during intestinal tumorigenesis.
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Affiliation(s)
- Mandayam O. Nandan
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia 30322, U.S.A
| | - Beth B. McConnell
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia 30322, U.S.A
| | - Amr M. Ghaleb
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia 30322, U.S.A
| | - Agnieszka B. Bialkowska
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia 30322, U.S.A
| | - Hongmiao Sheng
- Department of Surgery, Indiana University, Indianapolis, Indiana, 46202, U.S.A
| | - Jinyi Shao
- Department of Surgery, Indiana University, Indianapolis, Indiana, 46202, U.S.A
| | - Brian A. Babbin
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia 30322, U.S.A
| | - Sylvie Robine
- Morphogenesis and Intracellular Signalling, UMR 144, Institut Curie-CNRS, Paris, France
| | - Vincent W. Yang
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia 30322, U.S.A.,Winship Cancer Institute, Emory University, Atlanta, Georgia 30322, U.S.A.,Address correspondence to: Vincent W. Yang, M.D., Ph.D., 201 Whitehead Biomedical Research Building, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322 Tel: (404) 712−5638; Fax: (404) 727−5767;
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