Molecular basis for defective glycosylation and Pseudomonas pathogenesis in cystic fibrosis lung

doi:10.1073/pnas.241182598

Molecular basis for defective glycosylation and Pseudomonas pathogenesis in cystic fibrosis lung

Departments of ^*Microbiology and Immunology and ^‡Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109; and ^†Departments of Molecular Genetics and Microbiology and Cell Biology and Physiology, University of New Mexico Health Sciences Center, 915 Camino de Salud NE, Albuquerque, NM 87131

Edited by John J. Mekalanos, Harvard Medical School, Boston, MA, and approved September 26, 2001 (received for review April 11, 2001)

Abstract

The CFTR gene encodes a transmembrane conductance regulator, which is dysfunctional in patients with cystic fibrosis (CF). The mechanism by which defective CFTR (CF transmembrane conductance regulator) leads to undersialylation of plasma membrane glycoconjugates, which in turn promote lung pathology and colonization with Pseudomonas aeruginosa causing lethal bacterial infections in CF, is not known. Here we show by ratiometric imaging with lumenally exposed pH-sensitive green fluorescent protein that dysfunctional CFTR leads to hyperacidification of the trans-Golgi network (TGN) in CF lung epithelial cells. The hyperacidification of TGN, glycosylation defect of plasma membrane glycoconjugates, and increased P. aeruginosa adherence were corrected by incubating CF respiratory epithelial cells with weak bases. Studies with pharmacological agents indicated a role for sodium conductance, modulated by CFTR regulatory function, in determining the pH of TGN. These studies demonstrate the molecular basis for defective glycosylation of lung epithelial cells and bacterial pathogenesis in CF, and suggest a cure by normalizing the pH of intracellular compartments.

CFTR‖Pseudomonas aeruginosa‖pH-sensitive GFP‖sialyltransferases

Footnotes

↵ § To whom reprint requests should be addressed. E-mail: vderetic{at}salud.unm.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

CF,

cystic fibrosis;

CFTR,

CF transmembrane conductance regulator;

GPI,

glycosylphosphatidylinositol;

GFP,

green fluorescent protein;

PNA,

peanut agglutinin;

TGN,

trans-Golgi network