Phagosomal membrane rafts: azurophilic origin, Ca2+ dependence, and modulation by Streptococcus pyogenes bacteria
(English)Manuscript (preprint) (Other academic)
Uptake and killing of microorganisms by neutrophils involve tightly regulated membrane traffic events that are governed by complex signals. Many of these are raft-associated, which implies that raft dynamics may be important during phagosome formation. Locally restricted, calcium-dependent, parallel upregulation of markers for membrane rafts and azurophilic granules was observed at the site of phagocytosis of IgG-opsonized prey in human neutrophils. Subsequent internalization of the prey reduced the levels of these markers in the plasma membrane. Streptococcus pyogenes bacteria, that can survive phagocytosis by neutrophils, modulated phagosomal raft acquisition by means of M proteins. Continued, but not early, delivery of rafts to the membrane of phagosomes in neutrophils and HL-60 cells was independent of calcium, as was fusion between azurophilic granules and phagosomes. Nevertheless, calcium depletion affected bacterial killing kinetics. These findings suggest that early delivery of membrane rafts is important for phagosomal maturation in neutrophils and provide new mechanistic insight into the processes required for generation of bactericidal phagosomes.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-52261OAI: oai:DiVA.org:liu-52261DiVA: diva2:280964