Molecular mechanisms controlling CFTR gene expression in the airway

Zhaolin Zhang,Shih‐Hsing Leir,Marzena A Lewandowska,Christopher J Ott,Ann Harris

doi:10.1111/j.1582-4934.2011.01439.x

Abstract

The low levels of CFTR gene expression and paucity of CFTR protein in human airway epithelial cells are not easily reconciled with the pivotal role of the lung in cystic fibrosis pathology. Previous data suggested that the regulatory mechanisms controlling CFTR gene expression might be different in airway epithelium in comparison to intestinal epithelium where CFTR mRNA and protein is much more abundant. Here we examine chromatin structure and modification across the CFTR locus in primary human tracheal (HTE) and bronchial (NHBE) epithelial cells and airway cell lines including 16HBE14o- and Calu3. We identify regions of open chromatin that appear selective for primary airway epithelial cells and show that several of these are enriched for a histone modification (H3K4me1) that is characteristic of enhancers. Consistent with these observations, three of these sites encompass elements that have cooperative enhancer function in reporter gene assays in 16HBE14o- cells. Finally, we use chromosome conformation capture (3C) to examine the three-dimensional structure of nearly 800 kb of chromosome 7 encompassing CFTR and observe long-range interactions between the CFTR promoter and regions far outside the locus in cell types that express high levels of CFTR.

Highlights

The recent development of new technologies to identify regulatory elements in non-coding regions of the human genome and elucidate their function [1] has enabled rapid advances in our understanding of many important genes
We focus on primary human tracheal and bronchial epithelial cells and compare these to airway epithelial cell lines that are frequently used in cystic fibrosis (CF) research
All cell types that express CFTR show a DHS at the promoter as expected and NHBE, 16HBE14o- and Calu3 cells show a DHS in intron 11 that we identified in intestinal cells [5]

Summary

Introduction

The recent development of new technologies to identify regulatory elements in non-coding regions of the human genome and elucidate their function [1] has enabled rapid advances in our understanding of many important genes. One such gene is the cystic fibrosis transmembrane conductance regulator (CFTR), which when mutated causes the common inherited disorder cystic fibrosis (CF). CFTR is a large gene encompassing 189 kb of genomic DNA [2] and showing complex cell-type specific and temporal regulation Of particular note is the very wide range of levels of CFTR expression in different cell types, with up

Methods

Results

Conclusion