Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause the inherited disorder cystic fibrosis (CF). Lung disease is the major cause of CF morbidity, though CFTR expression levels are substantially lower in the airway epithelium than in pancreatic duct and intestinal epithelia, which also show compromised function in CF. Recently developed small molecule therapeutics for CF are highly successful for one specific CFTR mutation and have a positive impact on others. However, the low abundance of CFTR transcripts in the airway limits the opportunity for drugs to correct the defective substrate. Elucidation of the transcriptional mechanisms for the CFTR locus has largely focused on intragenic and intergenic tissue-specific enhancers and their activating trans-factors. Here, we investigate whether the low CFTR levels in the airway epithelium result from the recruitment of repressive proteins directly to the locus. Using an siRNA screen to deplete ∼1500 transcription factors (TFs) and associated regulatory proteins in Calu-3 lung epithelial cells, we identified nearly 40 factors that upon depletion elevated CFTR mRNA levels more than 2-fold. A subset of these TFs was validated in primary human bronchial epithelial cells. Among the strongest repressors of airway expression of CFTR were Krüppel-like factor 5 and Ets homologous factor, both of which have pivotal roles in the airway epithelium. Depletion of these factors, which are both recruited to an airway-selective cis-regulatory element at −35 kb from the CFTR promoter, improved CFTR production and function, thus defining novel therapeutic targets for enhancement of CFTR.
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April 2018
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DAPI staining of Candida tropicalis cell chromatin, imaged by laser scanning confocal microscopy. In this issue of the Biochemical Journal, Li et al. discuss the potential to induce apoptosis when treating Candida tropicalis with CGA-N12; for details see pages 1385–1396.
Research Article|
April 16 2018
A transcription factor network represses CFTR gene expression in airway epithelial cells
Michael J. Mutolo;
Michael J. Mutolo
1Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL 60614, U.S.A.
2Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, U.S.A.
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Shih-Hsing Leir;
Shih-Hsing Leir
1Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL 60614, U.S.A.
2Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, U.S.A.
3Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44016, U.S.A.
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Sara L. Fossum;
Sara L. Fossum
1Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL 60614, U.S.A.
2Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, U.S.A.
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James A. Browne;
James A. Browne
1Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL 60614, U.S.A.
2Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, U.S.A.
3Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44016, U.S.A.
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Ann Harris
1Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL 60614, U.S.A.
2Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, U.S.A.
3Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44016, U.S.A.
Correspondence: Ann Harris (ann.harris@case.edu)
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Publisher: Portland Press Ltd
Received:
January 16 2018
Revision Received:
March 19 2018
Accepted:
March 22 2018
Accepted Manuscript online:
March 23 2018
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2018
Biochem J (2018) 475 (7): 1323–1334.
Article history
Received:
January 16 2018
Revision Received:
March 19 2018
Accepted:
March 22 2018
Accepted Manuscript online:
March 23 2018
Citation
Michael J. Mutolo, Shih-Hsing Leir, Sara L. Fossum, James A. Browne, Ann Harris; A transcription factor network represses CFTR gene expression in airway epithelial cells. Biochem J 16 April 2018; 475 (7): 1323–1334. doi: https://doi.org/10.1042/BCJ20180044
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