scholarly journals Exploiting species differences to understand the CFTR Cl− channel

2015 ◽  
Vol 43 (5) ◽  
pp. 975-982 ◽  
Author(s):  
Samuel J. Bose ◽  
Toby S. Scott-Ward ◽  
Zhiwei Cai ◽  
David N. Sheppard
Keyword(s):  
Cystic Fibrosis ◽  
Phylogenetic Analysis ◽  
Abc Transporter ◽  
Genetic Disease ◽  
Species Differences ◽  
Anion Channel ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Aquatic Vertebrates ◽  
Cystic Fibrosis Transmembrane

The anion channel cystic fibrosis transmembrane conductance regulator (CFTR) is a unique ATP-binding cassette (ABC) transporter. CFTR plays a pivotal role in transepithelial ion transport as its dysfunction in the genetic disease cystic fibrosis (CF) dramatically demonstrates. Phylogenetic analysis suggests that CFTR first appeared in aquatic vertebrates fulfilling important roles in osmosensing and organ development. Here, we review selectively, knowledge of CFTR structure, function and pharmacology, gleaned from cross-species comparative studies of recombinant CFTR proteins, including CFTR chimeras. The data argue that subtle changes in CFTR structure can affect strongly channel function and the action of CF mutations.

scholarly journals Nonequilibrium Gating of CFTR on an Equilibrium Theme

Physiology ◽  
2012 ◽  
Vol 27 (6) ◽  
pp. 351-361 ◽  
Author(s):  
Kang-Yang Jih ◽  
Tzyh-Chang Hwang
Keyword(s):  
Cystic Fibrosis ◽  
Abc Transporter ◽  
Chloride Channel ◽  
Genetic Disease ◽  
Clinical Relevance ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Abc Protein ◽  
Gating Mechanism ◽  
Cystic Fibrosis Transmembrane

Malfunction of cystic fibrosis transmembrane conductance regulator (CFTR), a member of the ABC protein superfamily that functions as an ATP-gated chloride channel, causes the lethal genetic disease, cystic fibrosis. This review focuses on the most recent findings on the gating mechanism of CFTR. Potential clinical relevance and implications to ABC transporter function are also discussed.

scholarly journals Structural comparative modeling of multi-domain ΔF508 CFTR

2021 ◽  
Author(s):  
Eli Fritz McDonald ◽  
Hope Woods ◽  
Shannon Smith ◽  
Minsoo Kim ◽  
Clara T. Schoeder ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Rational Design ◽  
Anion Channel ◽  
Comparative Modeling ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Binding Domains ◽  
Δf508 Cftr ◽  
Domain Models ◽  
Cystic Fibrosis Transmembrane

Cystic Fibrosis (CF) is a common genetic disease caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), an epithelial anion channel expressed in several vital organs. Absence of functional CFTR results in imbalanced osmotic equilibrium and subsequent mucus build up in the lungs - which increases the risk of infection and eventually causes death. CFTR is an ATP binding cassette (ABC) transporter composed of two transmembrane domains (TMDs), two nucleotide binding domains (NBDs), and an unstructured regulatory domain. The most prevalent patient mutation is the deletion of F508 (ΔF508), making ΔF508 CFTR the primary target for current FDA approved CF therapies. However, no experimental multi-domain ΔF508 CFTR structure has been determined and few studies have modeled ΔF508 using multi-domain WT CFTR structures. Here, we used cryo-EM density data and Rosetta comparative modeling (RosettaCM) to compare a ΔF508 model with published experimental data on CFTR NBD1 thermodynamics. We then apply this modeling method to generate multi-domain WT and ΔF508 CFTR structural models. These models demonstrate the destabilizing effects of ΔF508 on NBD1 and the NBD1/TMD interface in both the closed and open conformation of CFTR. Furthermore, we modeled ΔF508/R1070W and ΔF508 bound to a the CFTR corrector VX-809. Our models reveal the stabilizing effects of R1070W and VX-809 on multi-domain models of ΔF508 CFTR and pave the way for rational design of additional drugs that target ΔF508 CFTR for treatment of CF.

scholarly journals Molecular structure of the ATP-bound, phosphorylated human CFTR

2018 ◽  
Vol 115 (50) ◽  
pp. 12757-12762 ◽  
Author(s):  
Zhe Zhang ◽  
Fangyu Liu ◽  
Jue Chen
Keyword(s):  
Molecular Structure ◽  
Cystic Fibrosis ◽  
Conformational Changes ◽  
Anion Channel ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Common Features ◽  
Proper Functions ◽  
Cystic Fibrosis Transmembrane ◽  
Kinase A

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel important in maintaining proper functions of the lung, pancreas, and intestine. The activity of CFTR is regulated by ATP and protein kinase A-dependent phosphorylation. To understand the conformational changes elicited by phosphorylation and ATP binding, we present here the structure of phosphorylated, ATP-bound human CFTR, determined by cryoelectron microscopy to 3.2-Å resolution. This structure reveals the position of the R domain after phosphorylation. By comparing the structures of human CFTR and zebrafish CFTR determined under the same condition, we identified common features essential to channel gating. The differences in their structures indicate plasticity permitted in evolution to achieve the same function. Finally, the structure of CFTR provides a better understanding of why the G178R, R352Q, L927P, and G970R/D mutations would impede conformational changes of CFTR and lead to cystic fibrosis.

scholarly journals Rab11b Regulates the Apical Recycling of the Cystic Fibrosis Transmembrane Conductance Regulator in Polarized Intestinal Epithelial Cells

2009 ◽  
Vol 20 (8) ◽  
pp. 2337-2350 ◽  
Author(s):  
Mark R. Silvis ◽  
Carol A. Bertrand ◽  
Nadia Ameen ◽  
Franca Golin-Bisello ◽  
Michael B. Butterworth ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Epithelial Cells ◽  
Apical Membrane ◽  
Expression System ◽  
Anion Channel ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
T84 Cells ◽  
Anion Secretion ◽  
Cystic Fibrosis Transmembrane

The cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP/PKA-activated anion channel, undergoes efficient apical recycling in polarized epithelia. The regulatory mechanisms underlying CFTR recycling are understood poorly, yet this process is required for proper channel copy number at the apical membrane, and it is defective in the common CFTR mutant, ΔF508. Herein, we investigated the function of Rab11 isoforms in regulating CFTR trafficking in T84 cells, a colonic epithelial line that expresses CFTR endogenously. Western blotting of immunoisolated Rab11a or Rab11b vesicles revealed localization of endogenous CFTR within both compartments. CFTR function assays performed on T84 cells expressing the Rab11a or Rab11b GDP-locked S25N mutants demonstrated that only the Rab11b mutant inhibited 80% of the cAMP-activated halide efflux and that only the constitutively active Rab11b-Q70L increased the rate constant for stimulated halide efflux. Similarly, RNAi knockdown of Rab11b, but not Rab11a, reduced by 50% the CFTR-mediated anion conductance response. In polarized T84 monolayers, adenoviral expression of Rab11b-S25N resulted in a 70% inhibition of forskolin-stimulated transepithelial anion secretion and a 50% decrease in apical membrane CFTR as assessed by cell surface biotinylation. Biotin protection assays revealed a robust inhibition of CFTR recycling in polarized T84 cells expressing Rab11b-S25N, demonstrating the selective requirement for the Rab11b isoform. This is the first report detailing apical CFTR recycling in a native expression system and to demonstrate that Rab11b regulates apical recycling in polarized epithelial cells.

scholarly journals Cystic fibrosis transmembrane conductance regulator contributes to reacidification of alkalinized lysosomes in RPE cells

2012 ◽  
Vol 303 (2) ◽  
pp. C160-C169 ◽  
Author(s):  
Ji Liu ◽  
Wennan Lu ◽  
Sonia Guha ◽  
Gabriel C. Baltazar ◽  
Erin E. Coffey ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Anion Channel ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Rpe Cells ◽  
Lysosomal Ph ◽  
Baseline Levels ◽  
Interfering Rna ◽  
Cystic Fibrosis Transmembrane ◽  
Lysosomal Acidification

The role of the cystic fibrosis transmembrane conductance regulator (CFTR) in lysosomal acidification has been difficult to determine. We demonstrate here that CFTR contributes more to the reacidification of lysosomes from an elevated pH than to baseline pH maintenance. Lysosomal alkalinization is increasingly recognized as a factor in diseases of accumulation, and we previously showed that cAMP reacidified alkalinized lysosomes in retinal pigmented epithelial (RPE) cells. As the influx of anions to electrically balance proton accumulation may enhance lysosomal acidification, the contribution of the cAMP-activated anion channel CFTR to lysosomal reacidification was probed. The antagonist CFTRinh-172 had little effect on baseline levels of lysosomal pH in cultured human RPE cells but substantially reduced the reacidification of compromised lysosomes by cAMP. Likewise, CFTR activators had a bigger impact on cells whose lysosomes had been alkalinized. Knockdown of CFTR with small interfering RNA had a larger effect on alkalinized lysosomes than on baseline levels. Inhibition of CFTR in isolated lysosomes altered pH. While CFTR and Lamp1 were colocalized, treatment with cAMP did not increase targeting of CFTR to the lysosome. The inhibition of CFTR slowed lysosomal degradation of photoreceptor outer segments while activation of CFTR enhanced their clearance from compromised lysosomes. Activation of CFTR acidified RPE lysosomes from the ABCA4−/− mouse model of recessive Stargardt's disease, whose lysosomes are considerably alkalinized. In summary, CFTR contributes more to reducing lysosomal pH from alkalinized levels than to maintaining baseline pH. Treatment to activate CFTR may thus be of benefit in disorders of accumulation associated with lysosomal alkalinization.

Sign in / Sign up

Export Citation Format

Share Document