Caspase 6 activity initiates caspase 3 activation in cerebellar granule cell apoptosis.
Using a well documented ex vivo system consisting of rodent cerebellar granule cells (CGCs) the activation of caspases 3 and 6 during apoptosis induced by withdrawal of trophic support was analyzed. At the time of deprivation, the addition of the irreversible, broad-spectrum caspase inhibitor zVADfmk or the cell permeable, caspase 6 inhibitor CP-VEID-cho can transiently suppress the appearance of apoptosis, including the early appearance of DNA fragmentation. Using immunoblotting and fluorogenic peptide assays we observe deprivation-induced activation of caspases 3 and 6, but not caspase 9. Furthermore, active caspase 6 is capable of processing and activating procaspase 3 in cellular extracts prepared from non-apoptotic CGCs, whereas caspase 3 failed to activate caspase 6. In consonant with this, the cell permeable caspase 6 inhibitor prevented deprivation-induced caspase 3 activation whereas a cell permeable caspase 3 inhibitor, CP-DEVD-cho, had no effect on caspase 6 activation. This would indicate that caspase 6 is a significant inducer of the early caspase 3 activity in apoptotic CGCs.
Fujisawa Institute for Neuroscience in Edinburgh, The Department of Neuroscience, The University of Edinburgh, Edinburgh EH8 9JZ, UK. Timothy.Allsopp@ed.ac.uk
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TE
Allsopp
J
J
McLuckie
L E
LE
Kerr
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M
Macleod
J
J
Sharkey
J S
JS
Kelly
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D053178:Caspase 6; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology* / Q000201:enzymology*; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats
D000590:Amino Acid Chloromethyl Ketones; D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; C110923:acetyl-valyl-isoleucyl-aspartyl-aldehyde; C108637:aspartyl-glutamyl-valyl-aspartal; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C505410:Casp3 protein, rat; C505518:Casp6 protein, rat; D053148:Caspase 3; D053178:Caspase 6; D020169:Caspases