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: Hyungseoph J Cho, Heon Yung Gee, Kyung-Hwa Baek, Sung-Kyun Ko, Jong-Moon Park, Hookeun Lee, Nam-Doo Kim, Min Goo Lee, Injae Shin
• Journal: Journal of the American Chemical Society (J Am Chem Soc) Vol. 133 Issue 50 Pg. 20267-76 (Dec 21 2011) ISSN: 1520-5126 [Electronic] United States
• PMID: 22074182 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2011 American Chemical Society

Chemical References

• Benzamides
• HSC70 Heat-Shock Proteins
• Imidazoles
• apoptozole
• Cystic Fibrosis Transmembrane Conductance Regulator
• Adenosine Triphosphatases

Topics

• Adenosine Triphosphatases (chemistry, metabolism)
• Benzamides (chemistry, metabolism)
• Binding Sites
• Cell Line
• Cystic Fibrosis Transmembrane Conductance Regulator (genetics, metabolism)
• HSC70 Heat-Shock Proteins (metabolism)
• Humans
• Imidazoles (chemistry, metabolism)
• Magnetic Resonance Spectroscopy
• Mutation
• Protein Transport
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
• Ubiquitination