title: PKC epsilon -mediated ERK1/2 activation involved in radiation-induced cell death in NIH3T3 cells.
abstract: Protein kinase C (PKC) isoforms play distinct roles in cellular functions. We have previously shown that ionizing radiation activates PKC isoforms (alpha, delta, epsilon, and zeta), however, isoform-specific sensitivities to radiation and its exact mechanisms in radiation mediated signal transduction are not fully understood. In this study, we showed that overexpression of PKC isoforms (alpha, delta, epsilon, and zeta) increased radiation-induced cell death in NIH3T3 cells and PKC epsilon overexpression was predominantly responsible. In addition, PKC epsilon overexpression increased ERK1/2 activation without altering other MAP-kinases such as p38 MAPK or JNK. Co-transfection of dominant negative PKC epsilon (PKC epsilon -KR) blocked both PKC epsilon -mediated ERK1/2 activation and radiation-induced cell death, while catalytically active PKC epsilon construction augmented these phenomena. When the PKC epsilon overexpressed cells were pretreated with PD98059, MEK inhibitor, radiation-induced cell death was inhibited. Co-transfection of the cells with a mutant of ERK1 or -2 (ERK1-KR or ERK2-KR) also blocked these phenomena, and co-transfection with dominant negative Ras or Raf cDNA revealed that PKC epsilon -mediated ERK1/2 activation was Ras-Raf-dependent. In conclusion, PKC epsilon -mediated ERK1/2 activation was responsible for the radiation-induced cell death.
authors.affiliation: Laboratory of Radiation Effect, Korea Cancer Center Hospital, 215-4 Gongneung-Dong, Nowon-Ku, 139-706, Seoul, South Korea.
authors.forename: Yoon-Jin
authors.initials: YJ
authors.lastname: Lee
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Soh
authors.forename: Doo-Il
authors.initials: DI
authors.lastname: Jeoung
authors.forename: Chul-Koo
authors.initials: CK
authors.lastname: Cho
authors.forename: Gil Ja
authors.initials: GJ
authors.lastname: Jhon
authors.forename: Su-Jae
authors.initials: SJ
authors.lastname: Lee
authors.forename: Yun-Sil
authors.initials: YS
authors.lastname: Lee
mesh_terms: D016475:3T3 Cells / Q000378:metabolism / Q000528:radiation effects*; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011493:Protein Kinase C / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; C497256:Prkce protein, mouse; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one