Document Detail

An Essential Role of STIM1, Orai1, and S100A8-A9 Proteins for Ca2+ Signaling and Fc{gamma}R-Mediated Phagosomal Oxidative Activity.
MedLine Citation:
PMID:  21239714     Owner:  NLM     Status:  In-Data-Review    
Phagocytosis is a process of innate immunity that allows for the enclosure of pathogens within the phagosome and their subsequent destruction through the production of reactive oxygen species (ROS). Although these processes have been associated with increases of intracellular Ca(2+) concentrations, the mechanisms by which Ca(2+) could regulate the different phases of phagocytosis remain unknown. The aim of this study was to investigate the Ca(2+) signaling pathways involved in the regulation of FcγRs-induced phagocytosis. Our work focuses on IgG-opsonized zymosan internalization and phagosomal ROS production in DMSO-differentiated HL-60 cells and neutrophils. We found that chelation of intracellular Ca(2+) by BAPTA or emptying of the intracellular Ca(2+) store by thapsigargin reduced the efficiency of zymosan internalization. Using an small interfering RNA strategy, our data establish that the observed Ca(2+) release occurs through two isoforms of inositol 1,4,5-triphosphate receptors, ITPR1 and ITPR3. In addition, we provide evidence that phagosomal ROS production is dependent on extracellular Ca(2+) entry. We demonstrate that the observed Ca(2+) influx is supported by ORAI calcium release-activated calcium modulator 1 (Orai1) and stromal interaction molecule 1 (STIM1). This result suggests that extracellular Ca(2+) entry, which is required for ROS production, is mediated by a store-operated Ca(2+) mechanism. Finally, our data identify the complex formed by S100A8 and S100A9 (S100 calcium-binding protein A8 and A9 complex), two Ca(2+)-binding proteins, as the site of interplay between extracellular Ca(2+) entry and intraphagosomal ROS production. Thus, we demonstrate that FcγR-mediated phagocytosis requires intracellular Ca(2+) store depletion for the internalization phase. Then phagosomal ROS production requires extracellular Ca(2+) entry mediated by Orai1/STIM1 and relayed by S100A8-A9 as Ca(2+) sensor.
Natacha Steinckwich; Véronique Schenten; Chantal Melchior; Sabrina Bréchard; Eric J Tschirhart
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Publication Detail:
Type:  Journal Article     Date:  2011-01-14
Journal Detail:
Title:  Journal of immunology (Baltimore, Md. : 1950)     Volume:  186     ISSN:  1550-6606     ISO Abbreviation:  J. Immunol.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-02-03     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985117R     Medline TA:  J Immunol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2182-91     Citation Subset:  AIM; IM    
Life Sciences Research Unit, University of Luxembourg, L-1511 Luxembourg, Luxembourg.
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