title: Ceramide-induced translocation of protein kinase C-delta and -epsilon to the cytosol. Implications in apoptosis.
abstract: Ceramide is now recognized as an intracellular lipid signal mediator, which induces various kinds of cell functions including apoptosis. Ceramide-induced apoptosis was reported to be blocked by 12-O-tetradecanoylphorbol 13-acetate, a protein kinase C (PKC) activator, but its mechanism remained unclear. Therefore, we investigated whether ceramide has any effects on PKC in the induction of apoptosis. We here report that N-acetylsphingosine (synthetic membrane-permeable ceramide) induced translocation of PKC-delta and -epsilon isozymes from the membrane to the cytosol within 5 min in human leukemia cell lines. Treatment with sphingomyelinase, tumor necrosis factor-alpha, or anti-Fas antibody, all of which can induce apoptosis by generating natural ceramide, similarly induced cytosolic translocation of PKC-delta and -epsilon. In Fas-resistant cells anti-Fas antibody did not induce cytosolic translocation of PKC-delta and -epsilon because of no generation of ceramide, whereas N-acetylsphingosine induced apoptosis with cytosolic translocation of PKC-delta and -epsilon. Furthermore, both 12-O-tetradecanoylphorbol 13-acetate and a nonspecific kinase inhibitor, staurosporine, prevented ceramide-induced apoptosis by inhibiting cytosolic translocation of PKC-delta and -epsilon. These data suggest that cytosolic translocation of PKC-delta and -epsilon plays an important role in ceramide-mediated apoptosis.
authors.affiliation: Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawaramachi, Sakyo-ku, Kyoto 606, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sawai
authors.forename: T
authors.initials: T
authors.lastname: Okazaki
authors.forename: Y
authors.initials: Y
authors.lastname: Takeda
authors.forename: M
authors.initials: M
authors.lastname: Tashima
authors.forename: H
authors.initials: H
authors.lastname: Sawada
authors.forename: M
authors.initials: M
authors.lastname: Okuma
authors.forename: S
authors.initials: S
authors.lastname: Kishi
authors.forename: H
authors.initials: H
authors.lastname: Umehara
authors.forename: N
authors.initials: N
authors.lastname: Domae
mesh_terms: D000911:Antibodies, Monoclonal; D017209:Apoptosis / Q000187:drug effects; D002518:Ceramides / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019014:fas Receptor / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D002518:Ceramides; D007527:Isoenzymes; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C497258:PRKCD protein, human; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate