Activation of caspase-2 in apoptosis.
Members of the CED-3/interleukin-1beta-converting enzyme (ICE) protease (caspase) family are synthesized as proforms, which are proteolytically cleaved and activated during apoptosis. We report here that caspase-2 (ICH-1/NEDD-2), a member of the ICE family, is activated during apoptosis by another ICE member, a caspase-3 (CPP32)-like protease(s). When cells are induced to undergo apoptosis, endogenous caspase-2 is first cleaved into three fragments of 32-33 kDa and 14 kDa, which are then further processed into 18- and 12-kDa active subunits. Up to 50 microM N-acetyl-Asp-Glu-Val-Asp-aldehyde (DEVD-CHO), a caspase-3-preferred peptide inhibitor, inhibits caspase-2 activation and DNA fragmentation in vivo, but does not prevent loss of mitochondrial function, while higher concentrations of DEVD-CHO (>50 microM) inhibit both. In comparison, although the activity of caspase-3 is very sensitive to the inhibition of DEVD-CHO (<50 nM), inhibition of caspase-3 activation as marked by processing of the proform requires more than 100 microM DEVD-CHO. Our results suggest that the first cleavage of caspase-2 is accomplished by a caspase-3-like activity, and other ICE-like proteases less sensitive to DEVD-CHO may be responsible for activation of caspase-3 and loss of mitochondrial function.
Li
H
H
Cardiovascular Research Center, Massachusetts General Hospital-East, Charlestown, Massachusetts 02129 and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.
Bergeron
L
L
Cryns
V
V
Pasternack
M S
MS
Zhu
H
H
Shi
L
L
Greenberg
A
A
Yuan
J
J
D017209:Apoptosis; D053143:Caspase 2; D053148:Caspase 3; D020169:Caspases; D002474:Cell-Free System; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism; D006801:Humans; D008928:Mitochondria; D009842:Oligopeptides / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D013379:Substrate Specificity; D013601:T-Lymphocytes; D013602:T-Lymphocytes, Cytotoxic / Q000201:enzymology; D013997:Time Factors; D014407:Tumor Cells, Cultured
D015853:Cysteine Proteinase Inhibitors; D004792:Enzyme Precursors; D009842:Oligopeptides; D011506:Proteins; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; C490360:CASP2 protein, human; C505407:CASP3 protein, human; D053143:Caspase 2; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases