IgE-dependent Activation of Sphingosine Kinases 1 and 2 and Secretion of Sphingosine 1-Phosphate Requires Fyn Kinase and Contributes to Mast Cell Responses

Ana Olivera,Yumi Yamashita,Kiyomi Mizugishi,Juan Rivera,Alasdair M Gilfillan,Yasuko Furumoto,Thomas Baumruker,Nicole Urtz,Haihua Gu,Richard L Proia

doi:10.1074/jbc.m508931200

Abstract

Engagement of the high affinity receptor for IgE (FcepsilonRI) on mast cells results in the production and secretion of sphingosine 1-phosphate (S1P), a lipid metabolite present in the lungs of allergen-challenged asthmatics. Herein we report that two isoforms of sphingosine kinase (SphK1 and SphK2) are expressed and activated upon FcepsilonRI engagement of bone marrow-derived mast cells (BMMC). Fyn kinase is required for FcepsilonRI coupling to SphK1 and -2 and for subsequent S1P production. Normal activation of SphK1 and -2 was restored by expression of wild type Fyn but only partly with a kinase-defective Fyn, indicating that induction of SphK1 and SphK2 depended on both catalytic and noncatalytic properties of Fyn. Downstream of Fyn, the requirements for SphK1 activation differed from that of SphK2. Whereas SphK1 was considerably dependent on the adapter Grb2-associated binder 2 and phosphatidylinositol 3-OH kinase, SphK2 showed minimal dependence on these molecules. Fyn-deficient BMMC were defective in chemotaxis and, as previously reported, in degranulation. These functional responses were partly reconstituted by the addition of exogenous S1P to FcepsilonRI-stimulated cells. Taken together with our previous study, which demonstrated delayed SphK activation in Lyn-deficient BMMC, we propose a cooperative role between Fyn and Lyn kinases in the activation of SphKs, which contributes to mast cell responses.

Highlights

Receptor stimulation of a variety of cell types induces the early activation of sphingosine kinase (SphK),5 a unique lipid kinase that generates the potent and versatile lipid mediator sphingosine-1-phosphate (S1P) [1, 2]
Taken together with our previous study, which demonstrated delayed SphK activation in Lyn-deficient bone marrow-derived mast cells (BMMC), we propose a cooperative role between Fyn and Lyn kinases in the activation of SphKs, which contributes to mast cell responses
Using conditions that differentiate between SphK1 and SphK2 activities (Fig. 1A), we found that SphK2 was a prominent SphK activity in wild type (WT) BMMC (Fig. 1B)

Summary

Introduction

Receptor stimulation of a variety of cell types induces the early activation of sphingosine kinase (SphK),5 a unique lipid kinase that generates the potent and versatile lipid mediator sphingosine-1-phosphate (S1P) [1, 2]. Taken together with our previous study, which demonstrated delayed SphK activation in Lyn-deficient BMMC, we propose a cooperative role between Fyn and Lyn kinases in the activation of SphKs, which contributes to mast cell responses.

Results

Conclusion