Altered biogenesis of deltaF508-CFTR following treatment with doxorubicin.
Cystic fibrosis (CF) is caused by mutations to the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The most common of these mutations is deletion of a phenylalanine residue at position 508 (Delta F508), which accounts for approximately 70% of all CF alleles. This mutation interferes with the biogenesis and maturation of Delta F508-CFTR to the plasma membrane. However, Delta F508-CFTR can partially function upon proper localization. Thus, pharmacological correction of Delta F508-CFTR maturation holds promise in CF therapy. Our previous studies indicate that a single non-cytotoxic dose of the anthracycline doxorubicin (Dox) significantly increase Delta F508-CFTR-associated chloride secretion in MDCK cells by increasing the expression of this protein at the apical plasma membrane. We report here that Dox alters the biogenesis of Delta F508-CFTR. Treatment with Dox increases the resistance of Delta F508-CFTR to trypsin digestion, possibly by expediting protein folding. Further, treatment with Dox reduces the amount of polyubiquitinated Delta F508-CFTR in cells and prolongs the half-life of this protein. Concomitantly, treatment with Dox decreases the association of Delta F508-CFTR with HSP70 but does not alter the expression of major HSP70 family members. Based on these results, we propose that Dox expedites the folding and maturation of Delta F508-CFTR by acting as a pharmacological chaperone, which consequently promotes the functional expression of this protein in MDCK cells.
Maitra
Rangan
R
Center for Organic and Medicinal Chemistry, RTI International, Research Triangle Park, NC, USA.
Hamilton
Joshua W
JW
D000818:Animals; D002460:Cell Line; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000096:biosynthesis* / Q000235:genetics*; D004285:Dogs; D004317:Doxorubicin / Q000494:pharmacology*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D010649:Phenylalanine / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017384:Sequence Deletion / Q000235:genetics*; D025801:Ubiquitin / Q000378:metabolism
D018840:HSP70 Heat-Shock Proteins; D025801:Ubiquitin; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D010649:Phenylalanine; D004317:Doxorubicin; D010447:Peptide Hydrolases