KLF4 activates NF[kappa]B signaling and esophageal epithelial inflammation via the Rho-related GTP-binding protein RHOF

Understanding the regulatory mechanisms within esophageal epithelia is essential to gain insight into the pathogenesis of esophageal diseases, which are among the leading causes of morbidity and mortality throughout the world. The zinc-finger transcription factor Krüppel-like factor (KLF4) is implicated in a large number of cellular processes, such as proliferation, differentiation, and inflammation in esophageal epithelia. In murine esophageal epithelia, Klf4 overexpression causes chronic inflammation which is mediated by activation of NF[kappa]B signaling downstream of KLF4, and this esophageal inflammation produces epithelial hyperplasia and subsequent esophageal squamous cell cancer. Yet, while NF[kappa]B activation clearly promotes esophageal inflammation, the mechanisms by which NF[kappa]B signaling is activated in esophageal diseases are not well understood. Here, we demonstrate that the Rho-related GTP-binding protein RHOF is activated by KLF4 in esophageal keratinocytes, leading to the induction of NF[kappa]B signaling. Moreover, RHOF is required for NF[kappa]B activation by KLF4 in esophageal keratinocytes and is also important for esophageal keratinocyte proliferation and migration. Finally, we find that RHOF is upregulated in eosinophilic esophagitis, an important esophageal inflammatory disease in humans. Thus, RHOF activation of NF[kappa]B in esophageal keratinocytes provides a potentially important and clinically-relevant mechanism for esophageal inflammation and inflammation-mediated esophageal squamous cell cancer.