Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent evidence suggests that CPP32 is an essential component of an aspartate-specific cysteine protease (ASCP) cascade responsible for apoptosis execution in mammalian cells. Activation of CPP32 could lead to activation of other downstream ASCPs, resulting in late morphological changes such as lamin cleavage and DNA fragmentation, observed in cells undergoing apoptosis. Here we describe the identification and cloning of a novel human ASCP named Mch6 from Jurkat T lymphocytes. We demonstrate that the pro-enzymes of Mch6 and the lamin-cleaving enzyme Mch2alpha are substrates for mature CPP32. Site-directed mutagenesis revealed that CPP32 processes pro-Mch6 preferentially at Asp330 to generate two subunits of molecular masses 37 kDa (p37) and 10 kDa (p10). However, CPP32 processes pro-Mch2alpha at three aspartate processing sites (Asp23, Asp179, and Asp193) to produce the large (p18) and small (p11) subunits of the mature Mch2alpha enzyme. The CPP32-processed Mch2alpha is capable of cleaving the VEIDN lamin cleavage site, indicating that CPP32 can, in fact, activate pro-Mch2alpha. Granzyme B at a concentration that allows processing and activation of CPP32 failed to process pro-Mch2alpha. However, incubation of pro-Mch2alpha with granzyme B in the presence of a cellular extract containing pro-CPP32 resulted in activation of pro-CPP32 and subsequent processing of pro-Mch2alpha. Interestingly, granzyme B can also process pro-Mch6 but at a site N-terminal to that cleaved by CPP32. These data suggest that Mch2alpha and Mch6 are downstream proteases activated in CPP32- and granzyme B-mediated apoptosis. This is the first demonstration of a protease cascade involving granzyme B, CPP32, Mch2alpha, and Mch6 and evidence that the lamin-cleaving enzyme Mch2 is a target of mature CPP32.
 ...
PMID:The Ced-3/interleukin 1beta converting enzyme-like homolog Mch6 and the lamin-cleaving enzyme Mch2alpha are substrates for the apoptotic mediator CPP32. 890 Feb 1

The Fas/APO-1-receptor associated cysteine protease Mch5 (MACH/FLICE) is believed to be the enzyme responsible for activating a protease cascade after Fas-receptor ligation, leading to cell death. The Fas-apoptotic pathway is potently inhibited by the cowpox serpin CrmA, suggesting that Mch5 could be the target of this serpin. Bacterial expression of proMch5 generated a mature enzyme composed of two subunits, which are derived from the pre-cursor proenzyme by processing at Asp-227, Asp-233, Asp-391, and Asp-401. We demonstrate that recombinant Mch5 is able to process/activate all known ICE/Ced-3-like cysteine proteases and is potently inhibited by CrmA. This contrasts with the observation that Mch4, the second FADD-related cysteine protease that is also able to process/activate all known ICE/Ced-3-like cysteine proteases, is poorly inhibited by CrmA. These data suggest that Mch5 is the most upstream protease that receives the activation signal from the Fas-receptor to initiate the apoptotic protease cascade that leads to activation of ICE-like proteases (TX, ICE, and ICE-relIII), Ced-3-like proteases (CPP32, Mch2, Mch3, Mch4, and Mch6), and the ICH-1 protease. On the other hand, Mch4 could be a second upstream protease that is responsible for activation of the same protease cascade in CrmA-insensitive apoptotic pathways.
 ...
PMID:Molecular ordering of the Fas-apoptotic pathway: the Fas/APO-1 protease Mch5 is a CrmA-inhibitable protease that activates multiple Ced-3/ICE-like cysteine proteases. 896 78

We report here the purification of the third protein factor, Apaf-3, that participates in caspase-3 activation in vitro. Apaf-3 was identified as a member of the caspase family, caspase-9. Caspase-9 and Apaf-1 bind to each other via their respective NH2-terminal CED-3 homologous domains in the presence of cytochrome c and dATP, an event that leads to caspase-9 activation. Activated caspase-9 in turn cleaves and activates caspase-3. Depletion of caspase-9 from S-100 extracts diminished caspase-3 activation. Mutation of the active site of caspase-9 attenuated the activation of caspase-3 and cellular apoptotic response in vivo, indicating that caspase-9 is the most upstream member of the apoptotic protease cascade that is triggered by cytochrome c and dATP.
 ...
PMID:Cytochrome c and dATP-dependent formation of Apaf-1/caspase-9 complex initiates an apoptotic protease cascade. 1505 83

Inhibitor of apoptosis (IAP) gene products play an evolutionarily conserved role in regulating programmed cell death in diverse species ranging from insects to humans. Human XIAP, cIAP1 and cIAP2 are direct inhibitors of at least two members of the caspase family of cell death proteases: caspase-3 and caspase-7. Here we compared the mechanism by which IAPs interfere with activation of caspase-3 and other effector caspases in cytosolic extracts where caspase activation was initiated by caspase-8, a proximal protease activated by ligation of TNF-family receptors, or by cytochrome c, which is released from mitochondria into the cytosol during apoptosis. These studies demonstrate that XIAP, cIAP1 and cIAP2 can prevent the proteolytic processing of pro-caspases -3, -6 and -7 by blocking the cytochrome c-induced activation of pro-caspase-9. In contrast, these IAP family proteins did not prevent caspase-8-induced proteolytic activation of pro-caspase-3; however, they subsequently inhibited active caspase-3 directly, thus blocking downstream apoptotic events such as further activation of caspases. These findings demonstrate that IAPs can suppress different apoptotic pathways by inhibiting distinct caspases and identify pro-caspase-9 as a new target for IAP-mediated inhibition of apoptosis.
 ...
PMID:IAPs block apoptotic events induced by caspase-8 and cytochrome c by direct inhibition of distinct caspases. 954 35

Previous studies have shown that Apaf-1 and caspase-9 in the presence of cytochrome c and dATP can form an initiating complex for an apoptotic protease cascade. We have developed a cytochrome c-dependent in vitro system in which caspases downstream of this initiation complex are activated. The activation of caspase-9 from zymogen form to active dimeric protease requires intrinsic enzymatic activity. In contrast, caspase-3 and caspase-7 zymogens are proteolytically processed by active caspase-9. Activation of the above caspases is blocked by a dominant negative form of caspase-9. The in vitro system displays surprising specificity in that other caspases, including 1, 2, 4, 8, 10, and 13, are not activated.
 ...
PMID:Activation of caspases triggered by cytochrome c in vitro. 959 97

Activation of procaspase-9 by Apaf-1 in the cytochrome c/dATP-dependent pathway requires proteolytic cleavage to generate the mature caspase molecule. To elucidate the mechanism of activation of procaspase-9 by Apaf-1, we designed an in vitro Apaf-1-procaspase-9 activation system using recombinant components. Here, we show that deletion of the Apaf-1 WD-40 repeats makes Apaf-1 constitutively active and capable of processing procaspase-9 independent of cytochrome c an dATP. Apaf-1-mediated processing of procaspase-9 occurs at Asp-315 by an intrinsic autocatalytic activity of procaspase-9 itself. We provide evidence that Apaf-1 can form oligomers and may facilitate procaspase-9 autoactivation by oligomerizing its precursor molecules. Once activated, caspase-9 can initiate a caspase cascade involving the downstream executioners caspase-3, -6, and -7.
 ...
PMID:Autoactivation of procaspase-9 by Apaf-1-mediated oligomerization. 965 78

Geranylgeraniol (GGO) at 50 microM induces apoptosis in HL-60 cells. We examined the effects of Zn2+ ions on this process. Treatment of HL-60 cells with Zn2+ ions inhibited subsequent GGO-induced fragmentation of DNA. In a cell-free system that consisted of a specific substrate for caspase-3 and a lysate of HL-60 cells that had been treated with 50 microM GGO, Zn2+ ions at concentrations above 0.1 mM inhibited the activity of caspase-3. The effect of Zn2+ ions on the processing of caspase-3 during GGO-induced apoptosis was investigated by Western blotting, which revealed that an inactive 32-kDa precursor of caspase-3 was cleaved, in response to GGO, to yield an activated 17-kDa enzyme. Treatment of HL-60 cells with Zn2+ ions inhibited the cleavage of the precursor by a protease that was induced by treatment with GGO, and inhibition of this processing was well correlated with the inhibition by Zn2+ ions of caspase-3 activity in the cell-free system. In cell-extracted cytosols, Zn2+ ions inhibited the cleavage of the 32-kDa precursor by caspase-9 (Aapf-3) that was activated by addition of cytochrome c and dATP. These results indicate that inhibition of GGO-induced apoptosis in HL-60 cells by Zn2+ ions might be due to inhibition by Zn2+ ions of the processing of a precursor to caspase-3.
 ...
PMID:Zinc ions prevent processing of caspase-3 during apoptosis induced by geranylgeraniol in HL-60 cells. 968 18

The apoptotic signal triggered by ligation of members of the death receptor family is promoted by sequential activation of caspase zymogens. We show here that in a purified system, the initiator caspases-8 and -10 directly process the executioner pro-caspase-3 with activation rates (kcat/Km) of 8.7 x 10(5) and 2.8 x 10(5) M-1 s-1, respectively. These rates are of sufficient magnitude to indicate direct processing in vivo. Differentially processed forms of caspase-3 that accumulate during its activation have similar rates of activation, activities, and specificities. The pattern and rate of caspase-8 induced activation of pro-caspase-3 in cytosolic extracts was the same as in a purified system. Moreover, immunodepletion of a putative intermediary in the pathway to activation, pro-caspase-9, was without consequence. Taken together these data demonstrate that the initiator caspase-8 can directly activate pro-caspase-3 without the requirement for an accelerator. The in vitro data thus help to deconvolute previous in vivo transfection studies which have debated the role of a direct versus indirect transmission of the apoptotic signal generated by ligation of death receptors.
 ...
PMID:Pro-caspase-3 is a major physiologic target of caspase-8. 976 24

Recent studies have demonstrated that Apaf-1 is the adaptor molecule which in the presence of cytosolic cytochrome c (cyt c) and dATP interacts with procaspase-9, resulting in the sequential cleavage and activity of caspase-9 and caspase-3, followed by apoptosis. In the present studies, we determined the effect of enforced overexpression of Apaf-1 on the apoptotic threshold in the human myeloid leukemia HL-60 cells. Our findings demonstrate that both transient and stable transfections resulted in a 2.5-fold higher expression of Apaf-1, which was associated with approximately a 5-fold increase in the percentage of apoptosis in the transfectants (HL-60/Apaf-1) as compared with the control HL-60/neo cells. In cells overexpressing either Bcl-2 or Bcl-xL, transient overexpression of Apaf-1 did not induce apoptosis. Stably overexpressing Apaf-1 levels significantly sensitized HL-60/Apaf-1 cells to apoptosis induced by clinically achievable concentrations of paclitaxel or etoposide (P < 0.01). This increase in paclitaxel- or etoposide-induced apoptosis of HL-60/Apaf-1 cells was not associated with any significant alterations in Bcl-2, Bcl-xL, Bax, Fas, or Fas ligand expression. It was, however, clearly associated with caspase-9 cleavage, as well as the poly(ADP-ribose) polymerase and DFF45 cleavage activity of caspase-3. Coexpression of the catalytically inactive, dominant-negative, mutant caspase-9, XIAP, or treatment with the caspase inhibitor, zVAD, significantly inhibited the increase in apoptosis of HL-60/Apaf-1 cells (P < 0.01). These data indicate that the intracellular levels of Apaf-1 is an important molecular determinant of the threshold for apoptosis induced by paclitaxel and etoposide.
 ...
PMID:Overexpression of Apaf-1 promotes apoptosis of untreated and paclitaxel- or etoposide-treated HL-60 cells. 978 1

We have previously shown that nitric oxide (NO) stimulates apoptosis in different human neoplastic lymphoid cell lines through activation of caspases not only via CD95/CD95L interaction, but also independently of such death receptors. Here we investigated mitochondria-dependent mechanisms of NO-induced apoptosis in Jurkat leukemic cells. NO donor glycerol trinitrate (at the concentration, which induces apoptotic cell death) caused (1) a significant decrease in the concentration of cardiolipin, a major mitochondrial lipid; (2) a downregulation in respiratory chain complex activities; (3) a release of the mitochondrial protein cytochrome c into the cytosol; and (4) an activation of caspase-9 and caspase-3. These changes were accompanied by an increase in the number of cells with low mitochondrial transmembrane potential and with a high level of reactive oxygen species production. Higher resistance of the CD95-resistant Jurkat subclone (APO-R) cells to NO-mediated apoptosis correlated with the absence of cytochrome c release and with less alterations in other mitochondrial parameters. An inhibitor of lipid peroxidation, trolox, significantly suppressed NO-mediated apoptosis in APO-S Jurkat cells, whereas bongkrekic acid (BA), which blocks mitochondrial permeability transition, provided only a moderate antiapoptotic effect. Transfection of Jurkat cells with bcl-2 led to a complete block of apoptosis due to the prevention of changes in mitochondrial functions. We suggest that the mitochondrial damage (in particular, cardiolipin degradation and cytochrome c release) induced by NO in human leukemia cells plays a crucial role in the subsequent activation of caspase and apoptosis.
 ...
PMID:Nitric-oxide-induced apoptosis in human leukemic lines requires mitochondrial lipid degradation and cytochrome C release. 1009 Sep 45


1 2 3 4 5 6 7 8 9 10 Next >>