CFTR (Cystic Fibrosis Transmembrane conductance Regulator) is a chloride channel that plays a critical role in mediating epithelial chloride secretion and absorption. Being a member of the ABC (ATP Binding Cassette) transporter superfamily, CFTR possesses two nucleotide binding domains (NBD1 and NBD2) characterized by the canonical Walker A and B motifs for ATP binding/hydrolysis, and the signature sequence whose function remains unknown. The functional importance of the signature sequence is attested by the fact that many disease-associated mutations are found in the signature sequence of either NBD1 (e.g., G551D) or NBD2 (e.g., G1349D). Interestingly, while the G551D mutation is associated with severe form CF, the G1349D mutation causes mild form disease, indicating that these two signature sequences play distinct roles in controlling CFTR function. Since the ABC transporter superfamily encompasses members that play a variety of physiological roles such as transport of cholesterol, drug resistance in cancers, cardiac membrane excitability and insulin secretion, understanding how CFTR works at a molecular level will have a broad impact on both basic sciences and clinical medicine. Recent solution of X-ray crystal structure of CFTR's N-terminal nucleotide binding domain (NBD1) has opened the door for detailed studies of the role of signature sequences in controlling CFTR function. The current proposal will employ a combination of electrophysiolgical, molecular biological, and structural biological techniques to address how mutations in the signature sequences cause CFTR dysfunction (Aim 1). Since defects of these mutations are likely to be amended by small-molecule, pharmacological reagents, we will investigate the mechanism by which some of the known compounds work on CFTR (Aim 2). Once succeeded, we will launch structure- based drug design to discover new compounds with high potency and efficacy. A clear understanding of the molecular mechanisms of CFTR dysfunction caused by mutations and the physical/chemical mechanism of drug actions on CFTR will aid in design of therapeutical reagents for the treatment of CF and other CFTR-associated diseases. Cystic fibrosis, the most common fatal genetic disease in the US, is caused by mutations of the CFTR protein. The goal of the application is to understand how disease-associated mutations cause dysfunction of CFTR and how small-molecule compounds restore the function of mutant CFTR.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK055835-13
Application #
8306675
Study Section
Cellular and Molecular Biology of the Kidney Study Section (CMBK)
Program Officer
Mckeon, Catherine T
Project Start
1999-09-30
Project End
2014-08-31
Budget Start
2012-09-01
Budget End
2014-08-31
Support Year
13
Fiscal Year
2012
Total Cost
$281,270
Indirect Cost
$82,475
Name
University of Missouri-Columbia
Department
Pharmacology
Type
Schools of Medicine
DUNS #
153890272
City
Columbia
State
MO
Country
United States
Zip Code
65211
Lin, Wen-Ying; Jih, Kang-Yang; Hwang, Tzyh-Chang (2014) A single amino acid substitution in CFTR converts ATP to an inhibitory ligand. J Gen Physiol 144:311-20
Sohma, Yoshiro; Yu, Ying-Chun; Hwang, Tzyh-Chang (2013) Curcumin and genistein: the combined effects on disease-associated CFTR mutants and their clinical implications. Curr Pharm Des 19:3521-8
Hwang, Tzyh-Chang; Kirk, Kevin L (2013) The CFTR ion channel: gating, regulation, and anion permeation. Cold Spring Harb Perspect Med 3:a009498
Jih, Kang-Yang; Hwang, Tzyh-Chang (2013) Vx-770 potentiates CFTR function by promoting decoupling between the gating cycle and ATP hydrolysis cycle. Proc Natl Acad Sci U S A 110:4404-9
Gao, Xiaolong; Bai, Yonghong; Hwang, Tzyh-Chang (2013) Cysteine scanning of CFTR's first transmembrane segment reveals its plausible roles in gating and permeation. Biophys J 104:786-97
Jih, Kang-Yang; Sohma, Yoshiro; Li, Min et al. (2012) Identification of a novel post-hydrolytic state in CFTR gating. J Gen Physiol 139:359-70
Yu, Ying-Chun; Miki, Haruna; Nakamura, Yumi et al. (2011) Curcumin and genistein additively potentiate G551D-CFTR. J Cyst Fibros 10:243-52
Cai, Zhiwei; Sohma, Yoshiro; Bompadre, Silvia G et al. (2011) Application of high-resolution single-channel recording to functional studies of cystic fibrosis mutants. Methods Mol Biol 741:419-41
Bai, Yonghong; Li, Min; Hwang, Tzyh-Chang (2011) Structural basis for the channel function of a degraded ABC transporter, CFTR (ABCC7). J Gen Physiol 138:495-507
Jih, Kang-Yang; Li, Min; Hwang, Tzyh-Chang et al. (2011) The most common cystic fibrosis-associated mutation destabilizes the dimeric state of the nucleotide-binding domains of CFTR. J Physiol 589:2719-31

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