Control of Bcl-2 expression by reactive oxygen species.
Reactive oxygen species (ROS) mediate apoptosis in many different cell types. We have previously shown that the antioxidant Mn(III) tetrakis(5,10,15,20-benzoic acid)porphyrin (MnTBAP) decreased intracellular ROS and prevented the apoptosis of activated T cells in vitro. To determine the mechanism(s) by which MnTBAP afforded such protection, we used Affymetrix (Santa Clara, CA) gene arrays to compare gene expression in T cells activated with staphylococcal enterotoxin B in vivo then cultured with or without MnTBAP. This analysis showed that the antioxidant increased the expression of Bcl-2, an antiapoptotic molecule whose levels are normally decreased by T cell activation. Culture with MnTBAP revealed a tight inverse correlation between the levels of Bcl-2 and ROS within T cells. In vivo, production of ROS in activated T cells occurred before Bcl-2 down-regulation. Furthermore, MnTBAP's ability to prevent death required the expression of Bcl-2 in most T cells. Finally, neither ROS production nor the effects on Bcl-2 expression required Bim, the Bcl-2 antagonist that mediates the death of activated T cells in vivo. Taken together, our results suggest that ROS sensitize T cells to apoptosis by decreasing expression of Bcl-2.
Hildeman
David A
DA
Division of Immunobiology, Department of Pediatrics, Children's Hospital Medical Center, Cincinnati, OH 45229, USA. david.hildeman@chmcc.org
Mitchell
Thomas
T
Aronow
Bruce
B
Wojciechowski
Sara
S
Kappler
John
J
Marrack
Philippa
P
D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D016923:Cell Death; D002470:Cell Survival; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D015854:Up-Regulation
D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D002352:Carrier Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D012313:RNA; D002374:Catalase