IgE-dependent activation of sphingosine kinases 1 and 2 and secretion of sphingosine 1-phosphate requires Fyn kinase and contributes to mast cell responses.
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.
Olivera
Ana
A
Molecular Inflammation Section, Molecular Immunology and Inflammation Branch, NIAMS, National Institutes of Health, Bethesda, Maryland 20892, USA.
Urtz
Nicole
N
Mizugishi
Kiyomi
K
Yamashita
Yumi
Y
Gilfillan
Alasdair M
AM
Furumoto
Yasuko
Y
Gu
Haihua
H
Proia
Richard L
RL
Baumruker
Thomas
T
Rivera
Juan
J
D000818:Animals; D015550:Cell Degranulation; D002460:Cell Line; D002633:Chemotaxis; D004789:Enzyme Activation; D006801:Humans; D007073:Immunoglobulin E / Q000502:physiology*; D008246:Lysophospholipids / Q000096:biosynthesis / Q000378:metabolism*; D008407:Mast Cells / Q000276:immunology*; D051379:Mice; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism*; D017455:Receptors, IgE / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D014162:Transfection; D019061:src-Family Kinases / Q000378:metabolism; D000099157:Sphingosine Kinase
D007073:Immunoglobulin E; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D051076:Proto-Oncogene Proteins c-fyn; D017455:Receptors, IgE; D013110:Sphingosine; D019061:src-Family Kinases; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate; C494960:Fyn protein, mouse; C060902:lyn protein-tyrosine kinase