Caspase-2 is not required for thymocyte or neuronal apoptosis even though cleavage of caspase-2 is dependent on both Apaf-1 and caspase-9.
We have generated rat monoclonal antibodies that specifically recognise caspase-2 from many species, including mouse, rat and humans. Using these antibodies, we have investigated caspase-2 expression, subcellular localisation and processing. We demonstrate that caspase-2 is expressed in most tissues and cell types. Cell fractionation and immunohistochemistry experiments show that caspase-2 is found in the nuclear and cytosolic fractions, including a significant portion present in the Golgi complex. We found that caspase-2 is processed in response to many apoptotic stimuli but experiments with caspase-2 deficient mice demonstrated that it is not required for apoptosis of thymocytes or dorsal root ganglia (DRG) neurons in response to a variety of cytotoxic stimuli. Caspase-2 processing does not occur in thymocytes lacking Apaf-1 or caspase-9, suggesting that in this cell type, activation of caspase-2 occurs downstream of apoptosome formation.
O'Reilly
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LA
The Walter and Eliza Hall Institute of Medical Research, Post Office, Royal Melbourne Hospital, Melbourne, Victoria 3050, Australia. oreilly@wehi.edu.au
Ekert
P
P
Harvey
N
N
Marsden
V
V
Cullen
L
L
Vaux
D L
DL
Hacker
G
G
Magnusson
C
C
Pakusch
M
M
Cecconi
F
F
Kuida
K
K
Strasser
A
A
Huang
D C S
DC
Kumar
S
S
D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity / Q000276:immunology; D017209:Apoptosis / Q000502:physiology*; D053477:Apoptotic Protease-Activating Factor 1; D053143:Caspase 2; D053453:Caspase 9; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000201:enzymology; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006056:Golgi Apparatus / Q000201:enzymology; D006367:HeLa Cells; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000201:enzymology* / Q000648:ultrastructure; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D013601:T-Lymphocytes / Q000166:cytology / Q000201:enzymology*
C506592:APAF1 protein, human; D000911:Antibodies, Monoclonal; C506593:Apaf1 protein, mouse; C506594:Apaf1 protein, rat; D053477:Apoptotic Protease-Activating Factor 1; D011506:Proteins; C506433:CASP9 protein, human; C506434:Casp9 protein, mouse; C506435:Casp9 protein, rat; D053143:Caspase 2; D053453:Caspase 9; D020169:Caspases