Defective acidification of intracellular organelles in cystic fibrosis.
The phenotype of cystic fibrosis (CF) includes abnormalities in transepithelial transport of Cl- (refs 1-5), decreased sialylation and increased sulphation and fucosylation of glycoproteins, and lung colonization with Pseudomonas. It is not apparent how these abnormalities are interrelated, nor how they result from loss of function of the CF gene-encoded transmembrane regulator (CFTR). We have previously shown that that the pH of a secretory granule is regulated by the vesicular conductance for Cl- (ref. 11). Here we find defective acidification in CF cells of the trans-Golgi/trans-Golgi network, of prelysosomes and of endosomes as a result of diminished Cl- conductance. Sialytation of proteins and lipids is reduced and ligand traffic altered. These abnormalities can result from defective acidification because vacuolar pH regulates glycoprotein processing and ligand transport. The CF phenotype is similar to that of alkalinized cells and acidification-defective mutatants.
Barasch
J
J
Department of Medicine, College of Physicians and Surgeons Columbia University, New York 10032.
Kiss
B
B
Prince
A
A
Saiman
L
L
Gruenert
D
D
al-Awqati
Q
Q
D002460:Cell Line; D018118:Chloride Channels; D003550:Cystic Fibrosis / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D014168:Transferrin / Q000378:metabolism
C505032:CFTR protein, human; D018118:Chloride Channels; D008565:Membrane Proteins; D014168:Transferrin; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D011188:Potassium