Enterocyte differentiation marker intestinal alkaline phosphatase is a target gene of the gut-enriched Krüppel-like factor

Authors:
  • ASAleem Siddique
    Aleem Siddique
  • JHJ. Welles Henderson
    J. Welles Henderson
  • MMMadhu S. Malo
    Madhu S. Malo
  • WZWenying Zhang
    Wenying Zhang
  • CAChristopher P. Athaide
    Christopher P. Athaide
  • MAMario A. Abedrapo
    Mario A. Abedrapo
  • XCXinming Chen
    Xinming Chen
  • VYVincent W. Yang
    Vincent W. Yang
  • RHRichard A. Hodin
    Richard A. Hodin
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Abstract
We have examined the role that the transcription factor gut-enriched Krüppel-like factor (KLF4 or GKLF) plays in activating the enterocyte differentiation marker gene intestinal alkaline phosphatase (IAP). A yeast one-hybrid screen was used to identify proteins interacting with a previously identified cis-element (IF-III) located within the human IAP gene promoter. DNA-protein interactions were determined by using EMSA. Northern blot analysis was used to study RNA expression in human colon cancer RKO cells engineered to overexpress KLF4. Transient transfections with IAP-luciferase reporter constructs were used to characterize the mechanisms by which KLF4 activates IAP transcription. The yeast one-hybrid screen and EMSA identified KLF4 as binding to IF-III. RKO cells induced to overexpress KLF4 demonstrated a corresponding dose-dependent increase in IAP expression, and EMSA with nuclear extract from these cells confirmed that KLF4 binds to the IF-III element. Transient transfections revealed that KLF4 transactivated the IAP gene largely via a critical segment in the IAP promoter that includes the IF-III cis-element. Mutant KLF4 constructs failed to fully activate IAP. We have identified the enterocyte differentiation marker IAP as a KLF4 target gene. IAP transactivation by KLF4 is likely mediated through a critical region located within the proximal IAP promoter region.

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