Chemical conjugation of ΔF508-CFTR corrector deoxyspergualin to transporter human serum albumin enhances its ability to rescue Cl⁻channel functions

Abstract

The most common mutation of the cystic fibrosis (CF) gene, the deletion of Phe508, encodes a protein (DeltaF508-CFTR) that fails to fold properly, thus mutated DeltaF508-cystic fibrosis transmembrane conductance regulator (CFTR) is recognized and degraded via the ubiquitin-proteasome endoplasmic reticulum-associated degradation pathway. Chemical and pharmacological chaperones and ligand-induced transport open options for designing specific drugs to control protein (mis)folding or transport. A class of compounds that has been proposed as having potential utility in DeltaF508-CFTR is that which targets the molecular chaperone and proteasome systems. In this study, we have selected deoxyspergualin (DSG) as a reference molecule for this class of compounds and for ease of cross-linking to human serum albumin (HSA) as a protein transporter. Chemical cross-linking of DSG to HSA via a disulfide-based cross-linker and its administration to cells carrying DeltaF508-CFTR resulted in a greater enhancement of DeltaF508-CFTR function than when free DSG was used. Function of the selenium-dependent oxidoreductase system was required to allow intracellular activation of HSA-DSG conjugates. The principle that carrier proteins can deliver pharmacological chaperones to cells leading to correction of defective CFTR functions is therefore proven and warrants further investigations.

A Cystic Fibrosis Respiratory Epithelial Cell Chronically Treated by Miglustat Acquires a Non–Cystic Fibrosis–Like Phenotype

“…Ion channel functions were assessed by single-cell fluorescence imaging using the potential-sensitive probe, bis-(1,3-diethylthiobarbituric acid)-trimethine oxonol (DiSBAC 2 [3]; Molecular Probes, Eugene, OR), as previously reported (20), but with minor changes: fluorescence intensity was recorded by confocal laser scanning microscopy using BioRad MRC 1,024 equipped with 15 mW Ar/Kr gas laser. Maximal resolution was obtained with an Olympus plan apo 360 oil, 1.4 numerical aperture, objective lens.…”

Mechanisms of the noxious inflammatory cycle in cystic fibrosis

“…Other evidences suggest that the excess of calcium sequestration in ER may contribute to the abnormal trafficking of CFTRΔF508. Indeed, it has been demonstrated that the decrease and the maintenance of low calcium levels in ER, by using SERCA inhibitors, prevent the interaction between CFTRΔF508 and chaperones and thus this restores CFTRΔF508 at the plasma membrane [ 76 , 77 ].…”

Folate-mediated targeting of albumin conjugates of paclitaxel obtained through a heterogeneous phase system

“…Based on these observations, a 50× excess was used in a typical preparation of targeted macromolecular paclitaxel. The results obtained show that the protein is protected by the Affi-gel matrix: the reduced thiol groups are fewer than 50% of those obtained through a solution reaction (Norez et al, 2008).…”