Restoration of W1282X CFTR activity by enhanced expression.
Cystic fibrosis results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Premature termination codons represent a common minority of CFTR mutations, and are caused by base pair substitutions that produce abnormal stop codons in the coding sequence. Select aminoglycosides induce "translational readthrough" of premature stop codons and have been shown to restore full-length functional protein in a number of preclinical and clinical settings. We studied two well-described premature termination codons found in the distal open reading frame of CFTR, W1282X and R1162X, expressed in polarizing and nonpolarizing cells. Our findings indicate that W1282X CFTR-expressing cells demonstrate significantly greater CFTR activity when overexpressed compared with R1162X CFTR cells, even when truncated protein is the predominant form. In addition, our results show that the combination of stimulated expression and stop codon suppression produces additive effects on CFTR-mediated ion transport. These findings provide evidence that W1282X CFTR exhibits membrane localization and retained chloride channel function after enhanced expression, and suggest that patients harboring this mutation may be more susceptible to CFTR rescue.
Rowe
Steven M
SM
Department of Medicine, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0006, USA. smrowe@uab.edu
Varga
Karoly
K
Rab
Andras
A
Bebok
Zsuzsa
Z
Byram
Kevin
K
Li
Yao
Y
Sorscher
Eric J
EJ
Clancy
John P
JP
D019943:Amino Acid Substitution; D002087:Butyrates / Q000494:pharmacology; D002460:Cell Line; D018389:Codon, Nonsense / Q000187:drug effects; D003550:Cystic Fibrosis / Q000235:genetics* / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005839:Gentamicins / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D017136:Ion Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013489:Suppression, Genetic; D014161:Transduction, Genetic
D002087:Butyrates; C505032:CFTR protein, human; D018389:Codon, Nonsense; D005839:Gentamicins; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C010680:antibiotic G 418