title: A small molecule that binds to an ATPase domain of Hsc70 promotes membrane trafficking of mutant cystic fibrosis transmembrane conductance regulator.
abstract: Cystic fibrosis transmembrane conductance regulator (CFTR) is a cell-surface anion channel that permeates chloride and bicarbonate ions. The most frequent mutation of CFTR that causes cystic fibrosis is the deletion of phenylalanine at position 508 (ΔF508), which leads to defects in protein folding and cellular trafficking to the plasma membrane. The lack of the cell-surface CFTR results in a reduction in the lifespan due to chronic lung infection with progressive deterioration of lung function. Hsc70 plays a crucial role in degradation of mutant CFTR by the ubiquitin-proteasome system. To date, various Hsc70 inhibitors and transcription regulators have been tested to determine whether they correct the defective activity of mutant CFTR. However, they exhibited limited or questionable effects on restoring the chloride channel activity in cystic fibrosis cells. Herein, we show that a small molecule apoptozole (Az) has high cellular potency to promote membrane trafficking of mutant CFTR and its chloride channel activity in cystic fibrosis cells. Results from affinity chromatography and ATPase activity assay indicate that Az inhibits the ATPase activity of Hsc70 by binding to its ATPase domain. In addition, a ligand-directed protein labeling and molecular modeling studies also suggest the binding of Az to an ATPase domain, in particular, an ATP-binding pocket. It is proposed that Az suppresses ubiquitination of ΔF508-CFTR maybe by blocking interaction of the mutant with Hsc70 and CHIP, and, as a consequence, it enhances membrane trafficking of the mutant.
authors.affiliation: Center for Biofunctional Molecules, Department of Chemistry, Yonsei University, Seoul 120-749, Korea.
authors.forename: Hyungseoph J
authors.initials: HJ
authors.lastname: Cho
authors.forename: Heon Yung
authors.initials: HY
authors.lastname: Gee
authors.forename: Kyung-Hwa
authors.initials: KH
authors.lastname: Baek
authors.forename: Sung-Kyun
authors.initials: SK
authors.lastname: Ko
authors.forename: Jong-Moon
authors.initials: JM
authors.lastname: Park
authors.forename: Hookeun
authors.initials: H
authors.lastname: Lee
authors.forename: Nam-Doo
authors.initials: ND
authors.lastname: Kim
authors.forename: Min Goo
authors.initials: MG
authors.lastname: Lee
authors.forename: Injae
authors.initials: I
authors.lastname: Shin
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D001549:Benzamides / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D021381:Protein Transport; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D054875:Ubiquitination
chemical_list: D001549:Benzamides; D050883:HSC70 Heat-Shock Proteins; D007093:Imidazoles; C000608805:apoptozole; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000251:Adenosine Triphosphatases