Bad Targets the Permeability Transition Pore Independent of Bax or Bak to Switch between Ca2+-Dependent Cell Survival and Death

Soumya Sinha Roy, Muniswamy Madesh, Erika Davies, Bruno Antonsson, Nika Danial, György Hajnóczky

Research output: Contribution to journalArticlepeer-review

109 Scopus citations


Calcium oscillations exert physiological control on mitochondrial energy metabolism and can also lead to mitochondrial membrane permeabilization and cell death. The outcome of the mitochondrial calcium signaling is altered by stress factors such as ceramide or staurosporine. However, the mechanism of this proapoptotic switch remains unclear. Using genetic, biochemical, pharmacological, and functional approaches, we here show that ceramide and staurosporine target PP2A and protein kinases A and C, respectively, in a mitochondria-associated signaling complex to induce dephosphorylation of the BH3-only protein Bad. Dephosphorylated Bad sensitizes the mitochondrial permeability transition pore (PTP) to Ca2+ through a Bcl-xL-sensitive and VDAC-mediated process. Furthermore, the Bad-induced sensitization of the PTP to Ca2+ does not require Bax or Bak. Thus, phospho-regulatory mechanisms converge on Bad to switch between the survival and apoptotic functions of mitochondrial calcium signaling by activating a mechanism whereby a BH3-only protein bypasses Bax/Bak and engages the PTP.

Original languageEnglish (US)
Pages (from-to)377-388
Number of pages12
JournalMolecular Cell
Issue number3
StatePublished - Feb 13 2009
Externally publishedYes



ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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