Krüppel-like Factor 5 is Essential for Maintenance of Barrier Function in Mouse Colon

Krüppel-like factor 5 (KLF5) is a member of the zinc finger family of transcription factors that regulates homeostasis of the intestinal epithelium. Previous studies suggested an indispensable role of KLF5 in maintaining intestinal barrier function. In the current study, we investigated the mechanisms by which KLF5 regulates colonic barrier function in vivo and in vitro. We used an inducible and a constitutive intestine-specific knockout mouse models ( designated as and as ) and studied an inducible knockdown in Caco-2 BBe cells using a lentiviral Tet-on system (Caco-2 BBe ). Specific knockout of in colonic tissues, either inducible or constitutive, resulted in increased intestinal permeability. The phenotype was accompanied by a significant reduction in , which encodes desmoglein-2, a desmosomal cadherin, at both mRNA and protein levels. Transmission electron microscopy showed alterations of desmosomal morphology in both knockdown Caco-2 BBe cells and knockout mouse colonic tissues. Inducible knockdown of in Caco-2BBe cells grown on Transwell plates led to impaired barrier function as evidenced by decreased transepithelial electrical resistance and increased paracellular permeability to fluorescein isothiocyanate-4 kDa dextran. Furthermore, DSG2 was significantly decreased in knockdown cells, and DSG2 overexpression partially rescued the impaired barrier function caused by knockdown. Electron microscopy studies demonstrated altered desmosomal morphology after knockdown. In combination with chromatin immunoprecipitation analysis and promoter study, our data show that KLF5 regulates intestinal barrier function by mediating the transcription of , a gene encoding a major component of desmosome structures. The study is original research on the direct function of a Krüppel-like factor on intestinal barrier function, which is commonly exerted by cell junctions, including tight junctions, adherens junctions, and desmosomes. Numerous previous studies were focused on tight junctions and adherens junctions. However, this study provided a new perspective on how the intestinal barrier function is regulated by KLF5 through DSG2, a component of desmosome complexes.