Abstract
Cerebellar granule neurons (CGNs) require depolarization for their survival in culture. When deprived of this stimulus, CGNs die via an intrinsic apoptotic cascade involving Bim induction, Bax translocation, cytochrome c release, and caspase-9 and -3 activation. Opening of the mitochondrial permeability transition pore (mPTP) is an early event during intrinsic apoptosis; however, the precise role of mPTP opening in neuronal apoptosis is presently unclear. Here, we show that mPTP opening acts as an initiating event to stimulate Bax translocation to mitochondria. A C-terminal (alpha9 helix) GFP-Bax point mutant (T182A) that constitutively localizes to mitochondria circumvents the requirement for mPTP opening and is entirely sufficient to induce CGN apoptosis. Collectively, these data indicate that the major role of mPTP opening in CGN apoptosis is to trigger Bax translocation to mitochondria, ultimately leading to cytochrome c release and caspase activation.
MeSH terms
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Animals
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Apoptosis Regulatory Proteins
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Apoptosis*
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Bcl-2-Like Protein 11
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Carrier Proteins / physiology
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Caspase 3
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Caspase 9
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Caspases / metabolism
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Cells, Cultured
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Cerebellum / cytology
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Culture Media, Serum-Free
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Cyclosporine / pharmacology
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Cytochromes c / metabolism
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Enzyme Activation
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Humans
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Ion Channels / antagonists & inhibitors
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Ion Channels / metabolism
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Ion Channels / physiology*
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Membrane Proteins / physiology
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Mitochondria / metabolism*
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Mitochondrial Membrane Transport Proteins
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Mitochondrial Permeability Transition Pore
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Neurons / cytology
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Neurons / metabolism*
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Point Mutation
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Potassium / metabolism
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Protein Transport
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Proto-Oncogene Proteins / physiology
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Proto-Oncogene Proteins c-bcl-2 / genetics
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Proto-Oncogene Proteins c-bcl-2 / metabolism*
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Rats
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Rats, Sprague-Dawley
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bcl-2-Associated X Protein
Substances
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Apoptosis Regulatory Proteins
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BAX protein, human
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BCL2L11 protein, human
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Bax protein, rat
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Bcl-2-Like Protein 11
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Bcl2l11 protein, rat
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Carrier Proteins
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Culture Media, Serum-Free
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Ion Channels
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Membrane Proteins
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Mitochondrial Membrane Transport Proteins
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Mitochondrial Permeability Transition Pore
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-bcl-2
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bcl-2-Associated X Protein
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Cyclosporine
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Cytochromes c
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CASP3 protein, human
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CASP9 protein, human
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Casp3 protein, rat
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Casp9 protein, rat
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Caspase 3
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Caspase 9
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Caspases
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Potassium