Ceramide Accelerates Dephosphorylation of Extracellular Signal-Regulated Kinase 1/2 to Decrease Prostaglandin D2 Production in RBL-2H3 Cells

In the present study, the effect of ceramide on antigen-stimulated phosphorylation of extracellular signal-regulated kinase (ERK) in the mechanism responsible for regulating production of prostaglandin (PG) D2 was investigated in the mast cell line, RBL-2H3 cells. Cell-permeable C6-ceramide (N-hexanoylsphingosine) suppressed antigen-stimulated phosphorylation of ERK1/2 and p38 mitogen-activated protein kinase. Ceramide also inhibited production of PGD2 and an increase in the activity of cytosolic phospholipase A2 (cPLA2), whereas it did not influence the tyrosine phosphorylation of major cellular proteins in response to antigen. The ceramide-induced inhibition of ERK1/2 phosphorylation and of cPLA2 activation was suppressed by orthovanadate, a tyrosine phosphatase inhibitor, but not by okadaic acid, a serine/threonine phosphatase inhibitor. Addition of ceramide to the lysate prepared from antigen-stimulated cells reduced the phosphorylated ERK1/2, and orthovanadate effectively prevented the reduction. These results suggest that ceramide accelerates the dephosphorylation of phosphorylated ERK1/2 via activation of a protein tyrosine phosphatase, thus preventing activation of cPLA2 and production of PGD2.