Submitted on July 5, 2007
Revised on December 21, 2007
Accepted on February 19, 2008
Chemical rescue of F508-CFTR mimics genetic repair in cystic fibrosis bronchial epithelial cells
Om V. Singh, Harvey B. Pollard, and Pamela L. Zeitlin
Pediatrics, Johns Hopkins School of Medicine, Baltimore, MD 21287
Corresponding Author: pzeitlin{at}jhmi.edu
In a previous study of 4-Phenylbutyrate (4-PBA) responsive proteins in cystic fibrosis (CF) IB3-1 bronchial epithelial cells, we identified 85 differentially expressed high abundance proteins from whole cellular lysate (Singh, O.V., Vij N., Mogayzel P.J. Jr., Jozwik C., Pollard, H.B. and Zeitlin, P.L. (2006) Pharmacoproteomics of 4-phenylbutyrate-treated IB3-1 cystic fibrosis bronchial epithelial cells. J. Proteome Res. 5(3), 562-571). In the present work we hypothesize that a subset of heat shock proteins that interact with cystic fibrosis transmembrane conductance regulator (CFTR) in common during chemical rescue and genetic repair will identify therapeutic networks for targeted intervention. Immunocomplexes were generated from total cellular lysates and three subcellular fractions (Endoplasmic reticulum [ER], cytosol, and plasma membrane [PM]) with anti-CFTR antisera from CF (IB3-1), chemical rescued-CF (4-PBA treated IB3-1) and genetically repaired-CF (IB3/S9 daughter cells repaired by gene transfer with AAV-(wild type) CFTR). CFTR interacting proteins were analyzed on two-dimensional (2D) gels and identified by mass spectrometry. A set of 16 proteins known to act in ER associated degradation (ERAD), were regulated in common and functionally connected to the protein processing, protein folding and inflammatory response. Some of these proteins were modulated exclusively in ER, cytosol, or PM. A subset of 4-PBA modulated ERAD chaperones (GRP94, HSP84, GRP78, GRP75, and GRP58) was observed to associate with the immature B form of CFTR in ER. HSP70 and HSC70 interacted with the C band (mature form) of CFTR at the cell surface. We conclude that chemically rescued CFTR associates with a specific set of HSP70 family proteins that mark therapeutic interactions and can be useful to correct both ion transport and inflammatory phenotypes in CF subjects.