HIF-dependent regulation of claudin-1 is central to intestinal epithelial tight junction integrity

BJ Saeedi, DJ Kao, DA Kitzenberg… - Molecular biology of …, 2015 - Am Soc Cell Biol
BJ Saeedi, DJ Kao, DA Kitzenberg, E Dobrinskikh, KD Schwisow, JC Masterson
Molecular biology of the cell, 2015Am Soc Cell Biol
Intestinal epithelial cells (IECs) are exposed to profound fluctuations in oxygen tension and
have evolved adaptive transcriptional responses to a low-oxygen environment. These
adaptations are mediated primarily through the hypoxia-inducible factor (HIF) complex.
Given the central role of the IEC in barrier function, we sought to determine whether HIF
influenced epithelial tight junction (TJ) structure and function. Initial studies revealed that
short hairpin RNA–mediated depletion of the HIF1β in T84 cells resulted in profound defects …
Intestinal epithelial cells (IECs) are exposed to profound fluctuations in oxygen tension and have evolved adaptive transcriptional responses to a low-oxygen environment. These adaptations are mediated primarily through the hypoxia-inducible factor (HIF) complex. Given the central role of the IEC in barrier function, we sought to determine whether HIF influenced epithelial tight junction (TJ) structure and function. Initial studies revealed that short hairpin RNA–mediated depletion of the HIF1β in T84 cells resulted in profound defects in barrier and nonuniform, undulating TJ morphology. Global HIF1α chromatin immunoprecipitation (ChIP) analysis identified claudin-1 (CLDN1) as a prominent HIF target gene. Analysis of HIF1β-deficient IEC revealed significantly reduced levels of CLDN1. Overexpression of CLDN1 in HIF1β-deficient cells resulted in resolution of morphological abnormalities and restoration of barrier function. ChIP and site-directed mutagenesis revealed prominent hypoxia response elements in the CLDN1 promoter region. Subsequent in vivo analysis revealed the importance of HIF-mediated CLDN1 expression during experimental colitis. These results identify a critical link between HIF and specific tight junction function, providing important insight into mechanisms of HIF-regulated epithelial homeostasis.
Am Soc Cell Biol