I'm seeing up-regulation of both pro- and anti-apoptotic genes upon oxidative stress in endothelial cells; it's a very strong trend over a 16 hour time-course - not sure how to explain this. Any pointers would be great, thank you!
I have seen this before in immune cell activation paradigms and stress experiments in cancer cells. Its likely due to different responses in different cell populations. In your experiment case, it could be that there are cells trying to adapt to oxidative stress and survive in which anti-apoptotic genes should be upregulated and cells which failed and are dying in which pro-apoptotic genes should be upregulated. But I am only speculating on what could be!
It's not terribly unusual. For starters you're dealing with two big signaling pathways that likely have a lot of crosstalk among different factors. Since you're stressing these cells its not surprising they are expressing both death genes and those likely associated with protective pathways. As Divya mentioned, you have a kind of heterogeneous population where some cells will be expressing a lot of protective factors and others will be dying. So you may really be seeing a range of responses all summed together.
It is not surprising to see up regulation of pro-apoptotic and anti-apoptotic factors under oxidative stress. Usually cells tend to trigger cytoprotective mechanims (prosurvival or anti-apoptotic pathways) upon oxidative stress which include activation of anti-oxidant mechanisms and prosurvival bcl-2 factors. Therefore, the fate of targeted cells depend on the intensity of the oxidative stress. If cells fail to stop oxidative stress, they undergo apoptosis. These two response can likely overlap in a certain time of cellular insult (switch). In organ, with different cell types, it is also possible to observed apoptosis in one cell type (e.g. endothelial cells) while other cells have triggered proliferation (fibroblasts)...
Under oxidative stress condition, Nrf2 is released from Keap1, enters nucleus, and activate various transcription of genes in which some of them are anti- as well as pro- apoptotic. As mentioned by others depending on the stage of the cell cycle, you will see enhanced gene regulations. This is normal to get mixed regulation. If you want to get either one, then synchronize the cells before treatment. Hope this helps.
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