BCL-2 Proapoptotic Proteins Distribution in U-87 MG Glioma Cells before and after Hypericin Photodynamic Action

Apoptosis is a key process in the development and maintenance of tissue homeostasis. This process of controlled cell death is tightly regulated by a balance between cell survival and damage signals. We focused our attention towards the intrinsic mitochondrial apoptotic pathway, where Bcl-2 family of proteins plays the major role. We were particularly interested in two pro-apoptotic players Bak and Bax. Here we investigated their role in apoptosis triggered by photodynamic action. We show the localization of Bax and Bak in U-87 MG human glioma cells incubated with photosensitizer hypericin (Hyp) before and after photodynamic action. Apoptotic stimulus by Hyp photodynamic action caused Bax translocation into mitochondria. However our results suggest that under these conditions there are two populations of mitochondria: one which contains Bax and Bak simultaneously, and is almost exclusively localized near the plasma membrane; the other which contains Bax only and is distributed throughout the cell. The different protein content and spatial distribution of these two populations suggest that they can play different roles in response to apoptotic stimuli.View Large Image | View Hi-Res Image | Download PowerPoint Slide