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Ceramide kinase promotes Ca2+ signaling near IgG-opsonized targets and enhances phagolysosomal fusion in COS-1 cellss⃞

Ceramide kinase promotes Ca2+ signaling near IgG-opsonized targets and enhances phagolysosomal fusion in COS-1 cellss⃞

Authors :
Laurence A. Boxer
Ji Biao Huang
Akira Abe
Thomas P. Shanley
James A. Shayman
Andrea J. Clark
Vania Hinkovska-Galcheva
Michael S. Borofsky
Miki Hiraoka
Susan M. VanWay
Howard R. Petty
Robin G. Kunkel
Frederick Lanni
Source :
Journal of Lipid Research, Vol 49, Iss 3, Pp 531-542 (2008)
Publication Year :
2008
Publisher :
Elsevier, 2008.

Abstract

Ceramide-1-phosphate (C1P) is a novel bioactive sphingolipid formed by the phosphorylation of ceramide catalyzed by ceramide kinase (CERK). In this study, we evaluated the mechanism by which increased C1P during phagocytosis enhances phagocytosis and phagolysosome formation in COS-1 cells expressing hCERK. Stable transfectants of COS-1 cells expressing FcgammaRIIA or both FcgammaRIIA/hCERK expression vectors were created. Cell fractionation studies demonstrated that hCERK and the transient receptor potential channel (TRPC-1) were enriched in caveolae fractions. Our data establish that both CERK and TRPC-1 localize to the caveolar microdomains during phagocytosis and that CERK also colocalizes with EIgG in FcgammaRIIA/hCERK-bearing COS-1 cells. Using high-speed fluorescence microscopy, FcgammaRIIA/hCERK transfected cells displayed Ca2+ sparks around the phagosome. In contrast, cells expressing FcgammaRIIA under identical conditions displayed little periphagosomal Ca2+ signaling. The enhanced Ca2+ signals were accompanied by enhanced phagolysosome formation. However, the addition of pharmacological reagents that inhibit store-operated channels (SOCs) reduced the phagocytic index and phagolysosomal fusion in hCERK transfected cells. The higher Ca2+ signal observed in hCERK transfected cells as well as the fact that CERK colocalized with EIgG during phagocytosis support our hypothesis that Ca2+ signaling is an important factor for increasing phagocytosis and is regulated by CERK in a manner that involves SOCs/TRPCs.

Details

Language :
English
ISSN :
00222275
Volume :
49
Issue :
3
Database :
OpenAIRE
Journal :
Journal of Lipid Research
Accession number :
edsair.doi.dedup.....b4df25460a9fb5a5b1ff79c5f4e5f6a2