CD16b associates with high-density, detergent-resistant membranes in human neutrophils.
CD16b is unique in that it is the only Fc receptor linked to the plasma membrane by a GPI (glycosylphosphatidylinositol) anchor. GPI-anchored proteins often preferentially localize to DRMs (detergent-resistant membranes) that are rich in sphingolipids and cholesterol and play an important role in signal transduction. Even though the responses to CD16b engagement have been intensively investigated, the importance of DRM integrity for CD16b signalling has not been characterized in human neutrophils. We provide direct evidence that CD16b constitutively partitions with both low- and high-density DRMs. Moreover, upon CD16b engagement, a significant increase in the amount of the receptor is observed in high-density DRMs. Similarly to CD16b, CD11b also resides in low- and high-density DRMs. In contrast with CD16b, the partitioning of CD11b in DRMs does not change in response to CD16b engagement. We also provide evidence for the implication of Syk in CD16b signalling and its partitioning to DRMs in resting and activated PMNs (polymorphonuclear neutrophils). Additionally, DRM-disrupting agents, such as nystatin and methyl-beta-cyclodextrin, alter cellular responses to CD16b receptor ligation. Notably, a significant increase in the mobilization of intracellular Ca2+ and in tyrosine phosphorylation of intracellular substrates after CD16b engagement is observed. Altogether, the results of this study provide evidence that high-density DRMs play a role in CD16b signalling in human neutrophils.
Fernandes
Maria J G
MJ
Department of Rheumatology and Immunology, CHUL Research Centre, Laval University, 2705 boulevarde Laurier, Sainte-Foy, Québec, Canada, G1V 4G2. maria.fernandes@crchul.ulaval.ca
Rollet-Labelle
Emmanuelle
E
Paré
Guillaume
G
Marois
Sébastien
S
Tremblay
Marie-Lisane
ML
Teillaud
Jean-Luc
JL
Naccache
Paul H
PH
D015703:Antigens, CD / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism*; D058851:GPI-Linked Proteins; D006801:Humans; D016177:Macrophage-1 Antigen / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology* / Q000378:metabolism*; D009761:Nystatin / Q000494:pharmacology; D011485:Protein Binding; D017452:Receptors, IgG / Q000378:metabolism*; D015398:Signal Transduction; D047392:beta-Cyclodextrins / Q000494:pharmacology
D015703:Antigens, CD; C428200:FCGR3B protein, human; D058851:GPI-Linked Proteins; D016177:Macrophage-1 Antigen; D017452:Receptors, IgG; D047392:beta-Cyclodextrins; D009761:Nystatin; C031215:betadex; D002118:Calcium