Kruppel-Like Factor-4 Transcriptionally Regulates VE-Cadherin Expression and Endothelial Barrier Function

Rationale: Vascular endothelial (VE)-cadherin localized at adherens junctions (AJs) regulates endothelial barrier function. Because WNT (wingless) signaling-induced activation of the transcription factor Kruppel-like factor (KLF) 4 may have an important role in mediating the expression of VE-cadherin and AJ integrity, we studied the function of KLF4 in regulating VE-cadherin expression and the control of endothelial barrier function. Objective: The goal of this study was to determine the transcriptional role of KLF4 in regulating VE-cadherin expression and endothelial barrier function. Methods and Results: Expression analysis, microscopy, chromatin immunoprecipitation, electrophoretic mobility shift assays, and VE-cadherin-luciferase reporter experiments demonstrated that KLF4 interacted with specific domains of VE-cadherin promoter and regulated the expression of VE-cadherin at AJs. KLF4 knockdown disrupted the endothelial barrier, indicating that KLF4 is required for normal barrier function. In vivo studies in mice showed augmented lipopolysaccharide-induced lung injury and pulmonary edema following Klf4 depletion. Conclusion: Our data show the key role of KLF4 in the regulation of VE-cadherin expression at the level of the AJs and in the acquisition of VE-cadherin-mediated endothelial barrier function. Thus, KLF4 maintains the integrity of AJs and prevents vascular leakage in response to inflammatory stimuli. (Circ Res. 2010;107:959-966.)