Hanson, C. Jane; Bootman, Martin D.; Distelhorst, Clark W.; Maraldi, Tullia and Roderick, H. Llewelyn
(2008).
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| DOI (Digital Object Identifier) Link: | http://dx.doi.org/doi:10.1016/j.ceca.2007.11.014 |
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| Google Scholar: | Look up in Google Scholar |
Abstract
Bcl-2 is an oncoprotein that is widely known to promote cell survival by inhibiting apoptosis. We explored the consequences of different expression paradigms on the cellular action of Bcl-2. Using either transient or stable transfection combined with doxycycline-inducible expression, we titrated the cellular concentration of Bcl-2. With each expression paradigm Bcl-2 was correctly targeted to the endoplasmic reticulum and mitochondria. However, with protocols that generated the greatest cellular concentrations of Bcl-2 the structure of these organelles was dramatically altered. The endoplasmic reticulum appeared to be substantially fragmented, whilst mitochondria coalesced into dense perinuclear structures. Under these conditions of high Bcl-2 expression, cells were not protected from pro-apoptotic stimuli. Rather Bcl-2 itself caused a significant amount of spontaneous cell death, and sensitised the cells to apoptotic agents such as staurosporine or ceramide. We observed a direct correlation between Bcl-2 concentration and spontaneous apoptosis. Expression of calbindin, a calcium buffering protein, or an enzyme that inhibited inositol 1,4,5-trisphosphate-mediated calcium release, significantly reduced cell death caused by Bcl-2 expression. We further observed that high levels of Bcl-2 expression caused lipid peroxidation and that the deleterious effects of Bcl-2 could be abrogated by the reactive oxygen species (ROS) scavenger Trolox. When stably expressed at low levels, Bcl-2 did not corrupt organelle structure or trigger spontaneous apoptosis. Rather, it protected cells from pro-apoptotic stimuli. These data reveal that high cellular concentrations of Bcl-2 lead to a calcium- and ROS-dependent induction of death. Selection of the appropriate expression paradigm is therefore crucial when investigating the biological role of Bcl-2.
| Item Type: | Journal Article |
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| Copyright Holders: | 2008 Elsevier Inc |
| ISSN: | 0143-4160 |
| Keywords: | calcium; apoptosis; Bcl-2; mitochondria |
| Academic Unit/Department: | Science > Life, Health and Chemical Sciences |
| Related URLs: | |
| Item ID: | 34872 |
| Depositing User: | Martin Bootman |
| Date Deposited: | 24 Oct 2012 13:42 |
| Last Modified: | 24 Oct 2012 20:47 |
| URI: | http://oro.open.ac.uk/id/eprint/34872 |
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