Combination of Correctors Rescue ΔF508-CFTR by Reducing Its Association with Hsp40 and Hsp27.

Abstract

Correcting the processing of ΔF508-CFTR, the most common mutation in cystic fibrosis, is the major goal in the development of new therapies for this disease. Here, we determined whether ΔF508 could be rescued by a combination of small-molecule correctors, and identified the mechanism by which correctors rescue the trafficking mutant of cystic fibrosis transmembrane conductance regulator (CFTR). We transfected COS-7 cells with ΔF508, created HEK-293 stably expressing ΔF508, and utilized CFBE41o(-) cell lines stably transduced with ΔF508. As shown previously, ΔF508 expressed less protein, was unstable at physiological temperature, and rapidly degraded. When the cells were treated with the combination C18 + C4 the mature C-band was expressed at the cell surface. After treatment with C18 + C4, we saw a lower rate of protein disappearance after translation was stopped with cycloheximide. To understand how this rescue occurs, we evaluated the change in the binding of proteins involved in endoplasmic reticulum-associated degradation, such as Hsp27 (HspB1) and Hsp40 (DnaJ). We saw a dramatic reduction in binding to heat shock proteins 27 and 40 following combined corrector therapy. siRNA experiments confirmed that a reduction in Hsp27 or Hsp40 rescued CFTR in the ΔF508 mutant, but the rescue was not additive or synergistic with C4 + 18 treatment, indicating these correctors shared a common pathway for rescue involving a network of endoplasmic reticulum-associated degradation proteins.

• Authors: Miquéias Lopes-Pacheco, Clément Boinot, Inna Sabirzhanova, Marcelo M Morales, William B Guggino, Liudmila Cebotaru
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 290 Issue 42 Pg. 25636-45 (Oct 16 2015) ISSN: 1083-351X [Electronic] United States
• PMID: 26336106 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• CFTR protein, human
• HSP27 Heat-Shock Proteins
• HSP40 Heat-Shock Proteins
• Cystic Fibrosis Transmembrane Conductance Regulator

Topics

• Animals
• COS Cells
• Chlorocebus aethiops
• Cystic Fibrosis Transmembrane Conductance Regulator (genetics, metabolism)
• HEK293 Cells
• HSP27 Heat-Shock Proteins (metabolism)
• HSP40 Heat-Shock Proteins (metabolism)
• Humans
• Mutation
• Protein Binding
• Temperature