Negative regulation of cytochrome c-mediated oligomerization of Apaf-1 and activation of procaspase-9 by heat shock protein 90.
The release of cytochrome c from mitochondria results in the formation of an Apaf-1-caspase-9 apoptosome and induces the apoptotic protease cascade by activation of procaspase-3. The present studies demonstrate that heat shock protein 90 (Hsp90) forms a cytosolic complex with Apaf-1 and thereby inhibits the formation of the active complex. Immunodepletion of Hsp90 depletes Apaf-1 and thereby inhibits cytochrome c-mediated activation of caspase-9. Addition of purified Apaf-1 to Hsp90-depleted cytosolic extracts restores cytochrome c-mediated activation of procaspase-9. We also show that Hsp90 inhibits cytochrome c-mediated oligomerization of Apaf-1 and thereby activation of procaspase-9. Furthermore, treatment of cells with diverse DNA-damaging agents dissociates the Hsp90-Apaf-1 complex and relieves the inhibition of procaspase-9 activation. These findings provide the first evidence for a negative cytosolic regulator of cytochrome c-dependent apoptosis and for involvement of a chaperone in the caspase cascade.
Pandey
P
P
Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
Saleh
A
A
Nakazawa
A
A
Kumar
S
S
Srinivasula
S M
SM
Kumar
V
V
Weichselbaum
R
R
Nalin
C
C
Alnemri
E S
ES
Kufe
D
D
Kharbanda
S
S
D000595:Amino Acid Sequence; D017209:Apoptosis; D053477:Apoptotic Protease-Activating Factor 1; D001667:Binding, Competitive; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D002474:Cell-Free System; D002846:Chromatography, Affinity; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D051745:Protein Kinase C-delta; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D020298:U937 Cells
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D003574:Cytochrome c Group; D004792:Enzyme Precursors; D018841:HSP90 Heat-Shock Proteins; D007527:Isoenzymes; D011506:Proteins; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases