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Activation of G551D CFTR channel with MPB-91: regulation by ATPase activity and phosphorylation
R Dérand1, L Bulteau-Pignoux, Y Mettey
1Laboratoire de Physiologie des Régulations Cellulaires, Unité Mixte de Recherche 6558, 86022 Poitiers, France.
Abstract:
We have designed and synthesized benzo[c]quinolizinium derivatives and evaluated their effects on the activity of G551D cystic fibrosis transmembrane conductance regulator (CFTR) expressed in Chinese hamster ovary and Fisher rat thyroid cells. We demonstrated, using iodide efflux, whole cell patch clamp, and short-circuit recordings, that 5-butyl-6-hydroxy-10-chlorobenzo[c]quinolizinium chloride (MPB-91) restored the activity of G551D CFTR (EC(50) = 85 microM) and activated CFTR in Calu-3 cells (EC(50) = 47 microM). MPB-91 has no effect on the ATPase activity of wild-type and G551D NBD1/R/GST fusion proteins or on the ATPase, GTPase, and adenylate kinase activities of purified NBD2. The activation of CFTR by MPB-91 is independent of phosphorylation because 1) kinase inhibitors have no effect and 2) the compound still activated CFTR having 10 mutated protein kinase A sites (10SA-CFTR). The new pharmacological agent MPB-91 may be an important candidate drug to ameliorate the ion transport defect associated with CF and to point out a new pathway to modulate CFTR activity.
Insights
A novel compound, MPB-91, effectively restores function to the G551D cystic fibrosis transmembrane conductance regulator (CFTR) protein. This discovery offers a potential new therapeutic avenue for cystic fibrosis by modulating CFTR activity.
Area of Science:
- Medicinal Chemistry
- Molecular Pharmacology
- Ion Channel Modulation
Background:
- Cystic Fibrosis (CF) is a genetic disorder caused by mutations in the CFTR gene.
- The G551D mutation impairs CFTR channel function, leading to ion transport defects.
- Developing small molecules to correct CFTR dysfunction is a key therapeutic goal.
Purpose of the Study:
- To design and synthesize novel benzo[c]quinolizinium derivatives.
- To evaluate their efficacy in restoring the activity of the G551D CFTR mutation.
- To investigate the mechanism of CFTR activation by the lead compound.
Main Methods:
- Synthesis of benzo[c]quinolizinium derivatives.
- Functional assays including iodide efflux, whole-cell patch clamp, and short-circuit current recordings.
- Biochemical assays measuring ATPase, GTPase, and adenylate kinase activities.
Main Results:
- MPB-91, a novel benzo[c]quinolizinium derivative, restored G551D CFTR activity (EC50 = 85 microM) and activated wild-type CFTR in Calu-3 cells (EC50 = 47 microM).
- MPB-91 did not affect the ATPase activity of CFTR NBD1 or NBD2 domains.
- CFTR activation by MPB-91 was independent of protein kinase A phosphorylation.
Conclusions:
- MPB-91 is a potent activator of CFTR, including the G551D mutant.
- The compound's mechanism of action is independent of phosphorylation and direct interaction with CFTR nucleotide-binding domains.
- MPB-91 represents a promising therapeutic candidate for cystic fibrosis.