Cholesterol-modulating agents selectively inhibit calcium influx induced by chemoattractants in human neutrophils.
The effects of cholesterol-perturbing agents on the mobilization of calcium induced upon the stimulation of human neutrophils by chemotactic factors were tested. Methyl-beta-cyclodextrin and filipin did not alter the initial peak of calcium mobilization but shortened the duration of the calcium spike that followed the addition of fMet-Leu-Phe. These agents also inhibited the influx of Mn(2+) induced by fMet-Leu-Phe or thapsigargin. Methyl-beta-cyclodextrin and filipin completely abrogated the mobilization of calcium induced by 10(-10) m platelet-activating factor, which at this concentration depends to a major extent on an influx of calcium as well as the influx of calcium induced by 10(-7) m platelet-activating factor. On the other hand, methyl-beta-cyclodextrin and filipin enhanced the mobilization of calcium induced by ligation of FcgammaRIIA, an agonist that did not induce a detectable influx of calcium. Finally, methyl-beta-cyclodextrin and filipin enhanced the stimulation of the profile of tyrosine phosphorylation, the activity of phospholipase D (PLD), and the production of superoxide anions induced by fMet-Leu-Phe. These results suggest that the calcium channels utilized by chemotactic factors in human neutrophils are either located in cholesterol-rich regions of the plasma membrane, or that the mechanisms that lead to their opening depend on the integrity of these microdomains.
Barabé
Frédéric
F
Canadian Institutes for Health Research group on the Molecular Mechanisms of Inflammation, Department of Medicine, Laval University, Québec, G1V 4G2 Canada.
Paré
Guillaume
G
Fernandes
Maria J G
MJ
Bourgoin
Sylvain G
SG
Naccache
Paul H
PH
D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D003505:Cyclodextrins / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism; D010766:Phosphorylation; D010972:Platelet Activating Factor / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D013481:Superoxides; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D010972:Platelet Activating Factor; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D013481:Superoxides; D014443:Tyrosine; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002784:Cholesterol; D010739:Phospholipase D; D002118:Calcium