Effect of PKC[alpha] expression on Bcl-2 phosphorylation and cell death by hypericin

• Published in: Apoptosis (London) Vol. 19; no. 12; p. 1779
• Main Authors: Joniova, Jaroslava, Misuth, Matus, Sureau, Franck, Miskovsky, Pavol, Nadova, Zuzana
• Format: Journal Article
• Language: English
• Published: London Springer Nature B.V 01.12.2014
• Subjects: Cell death
• ISSN: 1360-8185; 1573-675X
• DOI: 10.1007/s10495-014-1043-7

In order to explain the contribution of the protein kinase C[alpha] (PKC[alpha]) in apoptosis induced by photo-activation of hypericin (Hyp), a small interfering RNA was used for post-transcriptional silencing of pkc[alpha] gene expression. We have evaluated the influence of Hyp photo-activation on cell death in non-transfected and transfected (PKC[alpha]^sup -^) human glioma cells (U-87 MG). No significant differences were detected in cell survival between non-transfected and transfected PKC[alpha]^sup -^ cells. However, the type of cell death was notably affected by silencing the pkc[alpha] gene. Photo-activation of Hyp strongly induced apoptosis in non-transfected cells, but the level of necrotic cells in transfected PKC[alpha]^sup -^ 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 pkc[alpha] gene and the related decrease of PKC[alpha] level considerably affects the anti-apoptotic function and the anti-oxidant function of Bcl-2. This implies that PKC[alpha], as Bcl-2 kinase, indirectly protects U-87 MG cells against oxidative stress and subsequent cell death.[PUBLICATION ABSTRACT]