title: The equilibrium between long and very long chain ceramides is important for the fate of the cell and can be influenced by co-expression of CerS.
abstract: Ceramides are synthesized by six different ceramide synthases (CerS1-6), which differ in their specificity to produce ceramides of distinct chain length. We investigated the impact of CerS-co-transfection on ceramide production and apoptosis and proliferation in HCT-116 cells. Over-expression of CerS4 and CerS6 enhanced the level of C(16:0)-Cer twofold, that of C(18:0)- and C(20:0)-Cer up to sevenfold, in comparison to vector control transfected cells, whereas over-expression of CerS2 had no effect on the level of very long chain ceramide C(24:0)- and C(24:1)-Cer. Instead over-expression of CerS2 together with CerS4 or CerS6 increased the activity of CerS2 against very-long-chain ceramides about twofold. In contrast, co-expression of CerS4 with CerS6 inhibited slightly the production of C20:0-ceramide in comparison to cells over-expressing CerS4 alone, whereas the activity of CerS6 seemed not to be affected by other CerS. Interestingly, down-regulation of ELOVL1 had a comprehensive effect on the synthesis of very long chain ceramides which possibly point to a requirement for ELOVL1 expression for full CerS2-activity. Co-expression of CerS2 with CerS4/CerS6 reversed the inhibitory effect of long chain ceramides on cell proliferation and the induction of apoptosis. Even though we observed a twofold increase in total ceramide levels after co-expression of CerS2 with CerS4/CerS6, we detected no effect on cell proliferation. These data indicate that an increase in ceramide production per se is not critical for cell survival, but the equilibrium between long and very long chain ceramides and possibly protein/protein interactions determine the fate of the cell.
authors.affiliation: Pharmazentrum Frankfurt/ZAFES, Institut für Klinische Pharmakologie, Klinikum der Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Hartmann
authors.forename: Marthe-Susanna
authors.initials: MS
authors.lastname: Wegner
authors.forename: Ruth Anna
authors.initials: RA
authors.lastname: Wanger
authors.forename: Nerea
authors.initials: N
authors.lastname: Ferreirós
authors.forename: Yannick
authors.initials: Y
authors.lastname: Schreiber
authors.forename: Jessica
authors.initials: J
authors.lastname: Lucks
authors.forename: Susanne
authors.initials: S
authors.lastname: Schiffmann
authors.forename: Gerd
authors.initials: G
authors.lastname: Geisslinger
authors.forename: Sabine
authors.initials: S
authors.lastname: Grösch
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002518:Ceramides / Q000096:biosynthesis / Q000378:metabolism*; D015536:Down-Regulation; D000081031:Fatty Acid Elongases; D045325:HCT116 Cells; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis*; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering; D051049:Sphingosine N-Acyltransferase / Q000096:biosynthesis*; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis*
chemical_list: D002518:Ceramides; C000630949:ELOVL1 protein, human; D008565:Membrane Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases; C438311:CERS2 protein, human; C506123:CERS6 protein, human; D051049:Sphingosine N-Acyltransferase