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A Pseudomonas aeruginosa toxin (Cif) reduces plasma membrane CFTR by inactivating the deubiquitinating enzyme USP10
Author(s) -
Bomberger Jennifer,
Ye Siying,
O'Toole George,
Stanton Bruce
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.610.14
Subject(s) - deubiquitinating enzyme , endosome , endocytic cycle , pseudomonas aeruginosa , cystic fibrosis , microbiology and biotechnology , ubiquitin , cystic fibrosis transmembrane conductance regulator , endocytosis , chemistry , biology , biochemistry , intracellular , receptor , bacteria , genetics , gene
P . aeruginosa is an opportunistic pathogen critical to the pathogenesis of nosocomial infections, chronic obstructive pulmonary disease, ventilator‐associated pneumonia, cystic fibrosis, and bronchiectasis. Cif, a bacterial toxin secreted by clinical isolates of P. aeruginosa , reduces CFTR‐mediated chloride secretion by decreasing the endocytic recycling of CFTR. The aim of the current study was to investigate the mechanism by which Cif reduces the endocytic recycling of CFTR. Experiments in polarized human airway epithelial cells using Optiprep gradients revealed that Cif redirected CFTR from recycling endosomes to lysosomes for degradation, without affecting CFTR endocytosis. Cif redirected CFTR from recycling endosomes to lysosomes by increasing the amount of ubiquitinated CFTR (Ub‐CFTR). Employing proteomics and a deubiquitinating enzyme (DUB) activity assay, we observed that USP10 deubiquitinates CFTR, and that the Ras‐GAP SH3 domain binding protein‐1 (G3BP1) inactivates USP10. Moreover, Cif, by stabilizing USP10‐G3BP1 interaction, inactivates USP10 and thus, enhances the ubiquitination of CFTR, which is then directed to lysosomes for degradation. siRNA knockdown of G3BP1 can block the Cif effect on CFTR trafficking. These data suggest that chronic infection of P. aeruginosa will reduce mucociliary clearance, and thereby severely compromising the immune defenses of the lung.