Functional inactivation (by mutation) of the cystic fibrosis transmembrane conductance regulator (CFTR), a small conductance, cAMP activated chloride ion channel, leads to developmental defects that cause male infertility in humans. The mechanism by which inactivation of the CFTR gene causes infertility is poorly understood but is believed to be due in part to malformations or pathological changes in the male genital duct system. The goals of the proposed research are to decipher the transcriptional networks that regulate luminal environment in the epididymis, by building on our current understanding of the mechanisms regulating expression of the CFTR gene. Mutations in CFTR cause the devastating inherited disorder cystic fibrosis (CF). The CFTR channel makes an essential contribution to ion transport and the luminal environment in the epididymis and its loss causes obstruction and/or loss of the male genital ducts and subsequent infertility. The epididymis forms the proximal part of the excretory duct system of the male reproductive tract and is a complex organ that secretes and absorbs ions, water and inorganic solutes. Critically, it provides the correct luminal environment for normal sperm maturation. In normal epididymis the luminal environment is established and maintained through the functional cooperation of multiple ion channels, ion exchangers, solute carriers and transporters, though the mechanisms that coordinate the expression of these genes has not been well studied. In the first specific aim we will determine how modifications in the chromatin structure of the CFTR locus control its expression in the epididymis. We will evaluate the cis-acting enhancers and insulator elements that likely establish the looped conformation of the active locus and determine how trans-acting factors such as CTCF and cohesin influence this spatial organization. Moreover, we will investigate mechanisms and DNA- binding proteins that may suppress gene expression in cells where CFTR is less active or inactive. Experiments in the second specific aim will determine the transcriptional pathways that coordinate expression of ion channels, ion exchangers, transporters and solute carriers that interact with CFTR in the epididymis epithelium to establish and maintain the luminal environment. We will use a genome-wide approach (DNase- seq) to identify the cis-acting regulatory elements for genes encoding the proteins that contribute to ion and solute transport across the epididymal epithelium. Following mapping of these elements we will use combined bioinformatic and experimental approaches to identify the trans-acting factors that mediate the coordinated regulation of gene expression. Successful conduct of these studies will provide unique translational opportunities to modify male fertility. In disease states we may be able to reinstate the normal epididymal luminal environment and thereby restore fertility. Through modulation of this environment we may also be able to inhibit normal sperm maturation and thereby develop novel methods of birth control.

Public Health Relevance

Functional inactivation (by mutation) of the cystic fibrosis transmembrane conductance regulator (CFTR), a small conductance, cAMP activated chloride ion channel, leads to developmental defects in the genital duct system that cause male infertility in humans. The goals of the proposed research are to decipher the transcriptional networks that regulate luminal environment in the genital ducts, by building on our current understanding of the mechanisms regulating expression of the CFTR gene. Successful conduct of these studies will provide unique translational opportunities to modify male fertility. In infertile disease states we may be able to reinstate the normal epididymal luminal environment and thereby restore fertility. Modulation of this environment may provide ways to inhibit normal sperm maturation and thereby develop novel methods of birth control.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD068901-02
Application #
8316104
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Moss, Stuart B
Project Start
2011-08-10
Project End
2016-07-31
Budget Start
2012-08-01
Budget End
2013-07-31
Support Year
2
Fiscal Year
2012
Total Cost
$294,000
Indirect Cost
$94,000
Name
Children's Memorial Hospital (Chicago)
Department
Type
DUNS #
074438755
City
Chicago
State
IL
Country
United States
Zip Code
60611
Leir, Shih-Hsing; Browne, James A; Eggener, Scott E et al. (2015) Characterization of primary cultures of adult human epididymis epithelial cells. Fertil Steril 103:647-54.e1
Gosalia, Nehal; Neems, Daniel; Kerschner, Jenny L et al. (2014) Architectural proteins CTCF and cohesin have distinct roles in modulating the higher order structure and expression of the CFTR locus. Nucleic Acids Res 42:9612-22
Kerschner, Jenny L; Gosalia, Nehal; Leir, Shih-Hsing et al. (2014) Chromatin remodeling mediated by the FOXA1/A2 transcription factors activates CFTR expression in intestinal epithelial cells. Epigenetics 9:557-65
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Yigit, Erbay; Bischof, Jared M; Zhang, Zhaolin et al. (2013) Nucleosome mapping across the CFTR locus identifies novel regulatory factors. Nucleic Acids Res 41:2857-68
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Zhang, Zhaolin; Leir, Shih-Hsing; Harris, Ann (2013) Immune mediators regulate CFTR expression through a bifunctional airway-selective enhancer. Mol Cell Biol 33:2843-53
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Bischof, Jared M; Ott, Christopher J; Leir, Shih-Hsing et al. (2012) A genome-wide analysis of open chromatin in human tracheal epithelial cells reveals novel candidate regulatory elements for lung function. Thorax 67:385-91