Research ArticleImmunology

The VDAC2-BAK Rheostat Controls Thymocyte Survival

Science Signaling  25 Aug 2009:
Vol. 2, Issue 85, pp. ra48
DOI: 10.1126/scisignal.2000274

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Finessing Death

Because of their roles as proapoptotic members of the BCL-2 family of proteins, BAK and BAX must be carefully controlled. These proteins trigger the mitochondrial apoptotic pathway in response to death signals by undergoing homo-oligomerization, a process that is modulated by other members of the BCL-2 family. In addition, BAK, but not BAX, is kept in check by its interaction with the outer mitochondrial membrane porin protein VDAC2 (voltage-dependent anion channel 2), which prevents its oligomerization. Ren et al. deleted Vdac2 specifically in mouse thymocytes and found that these cells were more sensitive to various death signals, including that triggered by stimulation of the T cell receptor, than were thymocytes from control mice. The proapoptotic phenotype of these cells was rescued by concomitant deletion of Bak, but not Bax, thus providing in vivo evidence of the importance of the balance in the relative abundance of VDAC2 and BAX in determining responses to death signals.