Ceramide 1-Phosphate Is Required for the Translocation of Group IVA Cytosolic Phospholipase A2 and Prostaglandin Synthesis

Nadia F Lamour,Preeti Subramanian,Dayanjan S Wijesinghe,Robert V Stahelin,Joseph V Bonventre,Charles E Chalfant

doi:10.1074/jbc.m109.001677

Abstract

Little is known about the regulation of eicosanoid synthesis proximal to the activation of cytosolic phospholipase A(2)alpha (cPLA(2)alpha), the initial rate-limiting step. The current view is that cPLA(2)alpha associates with intracellular/phosphatidylcholine-rich membranes strictly via hydrophobic interactions in response to an increase of intracellular calcium. In opposition to this accepted mechanism of two decades, ceramide 1-phosphate (C1P) has been shown to increase the membrane association of cPLA(2)alpha in vitro via a novel site in the cationic beta-groove of the C2 domain (Stahelin, R. V., Subramanian, P., Vora, M., Cho, W., and Chalfant, C. E. (2007) J. Biol. Chem. 282, 20467-204741). In this study we demonstrate that C1P is a proximal and required bioactive lipid for the translocation of cPLA(2)alpha to intracellular membranes in response to inflammatory agonists (e.g. calcium ionophore and ATP). Last, the absolute requirement of the C1P/cPLA(2)alpha interaction was demonstrated for the production of eicosanoids using murine embryonic fibroblasts (cPLA(2)alpha(-/-)) coupled to "rescue" studies. Therefore, this study provides a paradigm shift in how cPLA(2)alpha is activated during inflammation.

Highlights

Little is known about the regulation of eicosanoid synthesis proximal to the activation of cytosolic phospholipase A2␣, the initial rate-limiting step
In this study we demonstrate that ceramide 1-phosphate (C1P) is a proximal and required bioactive lipid for the translocation of cPLA2␣ to intracellular membranes in response to inflammatory agonists
Once ceramide kinase (CERK) was confirmed as the anabolic enzyme for C1P formation in response to A23187 in our cell model, we examined the role of endogenous C1P on the translocation of cPLA2␣

Summary

Introduction

Little is known about the regulation of eicosanoid synthesis proximal to the activation of cytosolic phospholipase A2␣ (cPLA2␣), the initial rate-limiting step. In this study we demonstrate that C1P is a proximal and required bioactive lipid for the translocation of cPLA2␣ to intracellular membranes in response to inflammatory agonists (e.g. calcium ionophore and ATP).

Results

Conclusion