title: Effect of PKCα expression on Bcl-2 phosphorylation and cell death by hypericin.
abstract: In order to explain the contribution of the protein kinase Cα (PKCα) in apoptosis induced by photo-activation of hypericin (Hyp), a small interfering RNA was used for post-transcriptional silencing of pkcα gene expression. We have evaluated the influence of Hyp photo-activation on cell death in non-transfected and transfected (PKCα(-)) human glioma cells (U-87 MG). No significant differences were detected in cell survival between non-transfected and transfected PKCα(-) cells. However, the type of cell death was notably affected by silencing the pkcα gene. Photo-activation of Hyp strongly induced apoptosis in non-transfected cells, but the level of necrotic cells in transfected PKCα(-) cells increased significantly. The differences in cell death after Hyp photo-activation are demonstrated by changes in: (i) reactive oxygen species production, (ii) Bcl-2 phosphorylation on Ser70 (pBcl-2(Ser70)), (iii) cellular distributions of pBcl-2(Ser70) and (iv) cellular distribution of endogenous anti-oxidant glutathione and its co-localization with mitochondria. In summary, we suggest that post-transcriptional silencing of the pkcα gene and the related decrease of PKCα level considerably affects the anti-apoptotic function and the anti-oxidant function of Bcl-2. This implies that PKCα, as Bcl-2 kinase, indirectly protects U-87 MG cells against oxidative stress and subsequent cell death.
authors.affiliation: Department of Biophysics, Faculty of Science, University of Pavol Jozef Safarik, Jesenna 5, 041 54, Kosice, Slovak Republic.
authors.forename: Jaroslava
authors.initials: J
authors.lastname: Joniova
authors.forename: Matus
authors.initials: M
authors.lastname: Misuth
authors.forename: Franck
authors.initials: F
authors.lastname: Sureau
authors.forename: Pavol
authors.initials: P
authors.lastname: Miskovsky
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Nadova
mesh_terms: D000873:Anthracenes; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D015870:Gene Expression; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D009336:Necrosis; D010569:Perylene / Q000031:analogs & derivatives* / Q000494:pharmacology; D010766:Phosphorylation; D017319:Photosensitizing Agents / Q000494:pharmacology*; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012694:Serine / Q000378:metabolism
chemical_list: D000873:Anthracenes; D017319:Photosensitizing Agents; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D012694:Serine; D010569:Perylene; C004965:hypericin; D051571:Protein Kinase C-alpha