Corrector VX-809 promotes interactions between cytoplasmic loop one and the first nucleotide-binding domain of CFTR
TW Loo, DM Clarke - Biochemical Pharmacology, 2017 - Elsevier
TW Loo, DM Clarke
Biochemical Pharmacology, 2017•ElsevierA large number of correctors have been identified that can partially repair defects in folding,
stability and trafficking of CFTR processing mutants that cause cystic fibrosis (CF). The best
corrector, VX-809 (Lumacaftor), has shown some promise when used in combination with a
potentiator (Ivacaftor). Understanding the mechanism of VX-809 is essential for development
of better correctors. Here, we tested our prediction that VX-809 repairs folding and
processing defects of CFTR by promoting interactions between the first cytoplasmic loop …
stability and trafficking of CFTR processing mutants that cause cystic fibrosis (CF). The best
corrector, VX-809 (Lumacaftor), has shown some promise when used in combination with a
potentiator (Ivacaftor). Understanding the mechanism of VX-809 is essential for development
of better correctors. Here, we tested our prediction that VX-809 repairs folding and
processing defects of CFTR by promoting interactions between the first cytoplasmic loop …
Abstract
A large number of correctors have been identified that can partially repair defects in folding, stability and trafficking of CFTR processing mutants that cause cystic fibrosis (CF). The best corrector, VX-809 (Lumacaftor), has shown some promise when used in combination with a potentiator (Ivacaftor). Understanding the mechanism of VX-809 is essential for development of better correctors. Here, we tested our prediction that VX-809 repairs folding and processing defects of CFTR by promoting interactions between the first cytoplasmic loop (CL1) of transmembrane domain 1 (TMD1) and the first nucleotide-binding domain (NBD1). To investigate whether VX-809 promoted CL1/NBD1 interactions, we performed cysteine mutagenesis and disulfide cross-linking analysis of Cys-less TMD1 (residues 1–436) and ΔTMD1 (residues 437–1480; NBD1-R-TMD2-NBD2) truncation mutants. It was found that VX-809, but not bithiazole correctors, promoted maturation (exited endoplasmic reticulum for addition of complex carbohydrate in the Golgi) of the ΔTMD1 truncation mutant only when it was co-expressed in the presence of TMD1. Expression in the presence of VX-809 also promoted cross-linking between R170C (in CL1 of TMD1 protein) and L475C (in NBD1 of the ΔTMD1 truncation protein). Expression of the ΔTMD1 truncation mutant in the presence of TMD1 and VX-809 also increased the half-life of the mature protein in cells. The results suggest that the mechanism by which VX-809 promotes maturation and stability of CFTR is by promoting CL1/NBD1 interactions.
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