Exogenous C2-ceramide activates c-fos serum response element via Rac-dependent signalling pathway.
Ceramide is an important regulatory molecule implicated in a variety of biological processes in response to stress and cytokines. To understand the signal transduction pathway of ceramide to the nucleus, in the present study, we examined whether C2-ceramide, a cell permeable ceramide, activates c-fos serum response element (SRE). Treatment of Rat-2 fibroblast cells with C2-ceramide caused the stimulation of c-fos SRE-dependent reporter gene activity in a dose- and time-dependent manner by transient transfection analysis. Next, we examined the role of Rho family GTPases in the ceramide-induced signalling to SRE activation. By reporter gene analysis following transient transfections with various plasmids expressing a dominant negative mutant form of Cdc42, Rac1 or RhoA, C2-ceramide-induced SRE activation was shown to be selectively repressed by pEXV-RacN17 encoding a dominant negative mutant of Rac1, suggesting that Rac activity is essential for the signalling cascade of ceramide to the nucleus. In a further study to analyse the downstream mediator of Rac in the ceramide-signalling pathway, we observed that either pretreatment with mepacrine, a potent and specific inhibitor of phospholipase A2, or co-transfection with antisense cytosolic phospholipase A2 (cPLA2) oligonucleotide repressed the C2-ceramide-induced SRE activation selectively, implying a critical role of cPLA2 in C2-ceramide-induced signalling to nucleus. Consistent with these results, the translocation of cPLA2 protein as well as the release of arachidonic acid, a principal product of phospholipase A2, was rapidly induced by the addition of C2-ceramide in a Rac-dependent manner. Together, our findings suggest the critical role of 'Rac and subsequent activation of phospholipase A2' in ceramide-signalling to nucleus.
T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T20 T21 T22 T23 T24 T25 T26 T27 T28 T29 T30 T31 T32 T33 T34 T35 T36 T37 T38 T39 T40 T41
CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-N GENE-N GENE-Y GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-N GENE-N GENE-Y GENE-N GENE-N GENE-N GENE-N GENE-N GENE-N GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-N GENE-N GENE-N
Ceramide ceramide mepacrine C2-ceramide C2-ceramide arachidonic acid C2-ceramide ceramide ceramide C2-ceramide ceramide C2-ceramide ceramide C2-ceramide ceramide C2-ceramide Rac cytokines cytosolic phospholipase A2 cPLA2 SRE cPLA2 cPLA2 phospholipase A2 Rac Rac phospholipase A2 c-fos serum response element SRE c-fos SRE Rho GTPases SRE Cdc42 Rac1 RhoA SRE Rac1 Rac c-fos serum response element Rac