Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although ursodeoxycholic acid (UDC) is considered effective treatment for primary biliary cirrhosis (PBC), its mechanism of action is unclear. We tested the hypothesis that UDC is taken up by cholangiocytes and inhibits caspase 3-dependent apoptosis. We used the human cholangiocyte cell line (H69) and assessed it for expression and function of an apical sodium-dependent bile acid transporter (ASBT) by RT-PCR and uptake of tritiated taurocholic acid. We experimentally induced apoptosis in H69 cells using beauvericin (BV) and determined caspase 3 activation using a fluorogenic substrate and mitochondrial cytochrome c release (CC) into the cytosol by immunoblot analysis. We found that a functional ASBT is expressed by H69 cells as demonstrated by RT-PCR and bile acid uptake studies. Exposure of H69 cells to BV induced apoptosis in 39.4 +/- 1.3% of cells at 2 h (0.23 +/- 0.2% in controls). In contrast, when H69 cells were preincubated with GUDC (50 mM) for 24 h and then exposed to BV, apoptosis was inhibited by 23% (P < 0.03). In cholangiocytes pretreated with GUDC for 24 h and those treated with BV for 2 h, caspase 3-like activity was reduced by 79% and mitochondrial CC release was inhibited. In summary, the human cholangiocyte cell line H69 possesses a functional bile acid transporter, and GUDC decreases BV-induced apoptosis and inhibits activity of caspase 3 protease by blocking CC release from mitochondria. These preliminary results are consistent with our hypothesis that the beneficial effect of UDC on PBC may involve decreased apoptosis after GUDC uptake by cholangiocytes.
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PMID:GUDC inhibits cytochrome c release from human cholangiocyte mitochondria. 1032 2

The impact of ectopic expression of an N-terminal phosphorylation loop deletant Bcl-2 protein (Bcl-2Delta32-80) on the response of U937 monoblastic leukemia cells to paclitaxel was examined. In contrast to recent findings in HL-60 cells (Fang et al., Cancer Res. 58, 3202, 1998), U937 cells overexpressing Bcl-2Delta32-80 were significantly more resistant than those overexpressing full-length protein to caspase-3 and -9 activation, PARP degradation, and apoptosis induced by paclitaxel (500 nM; 18 h). Bcl-2Delta32-80 was also more effective than its full-length counterpart in opposing paclitaxel-mediated mitochondrial dysfunction, e.g., loss of mitochondrial membrane potential (Deltapsim) and cytochrome c release into the cytoplasm. Enhanced resistance of U937/Bcl-2Delta32-80 cells to paclitaxel was observed primarily in the G2M population. Together, these findings demonstrate that deletion of the Bcl-2 phosphorylation loop domain increases resistance of U937 leukemia cells to paclitaxel-mediated mitochondrial damage and apoptosis and suggest that factors other than, or in addition to, phosphorylation contribute to Bcl-2-related cytoprotectivity against paclitaxel in this model system.
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PMID:Loss of the bcl-2 phosphorylation loop domain increases resistance of human leukemia cells (U937) to paclitaxel-mediated mitochondrial dysfunction and apoptosis. 1033 17

The recent characterization of apoptotic protease-activating factor-1 (Apaf-1) in vertebrates as a putative homolog of the Caenorhabditis elegans gene, ced-4, indicates that the third major arm of the C. elegans programmed cell death machinery has also been conserved through evolution. Although apoptosis is now known to be important for ovarian follicular atresia in vertebrates, nothing is known of the role of Apaf-1 in ovarian function. Herein we show by immunohistochemical analysis that Apaf-1 is abundant in granulosa cells of early antral follicles whereas in vivo gonadotropin priming completely suppresses Apaf-1 expression and granulosa cell apoptosis. Western blot analysis of fractionated protein extracts prepared from granulosa cells before and after in vitro culture without hormonal support to induce apoptosis indicated that mitochondrial cytochrome c release, a biochemical step required for the activation of Apaf-1, occurs in granulosa cells cultured in vitro. Moreover, Western blot analysis of procaspase-3 processing, a principal downstream event set in motion by activated Apaf-1, indicated that healthy granulosa cells possess almost exclusively the inactive (pro-) form of the enzyme whereas granulosa cells deprived of hormonal support rapidly process procaspase-3 to the active enzyme. Lastly, we show that serum-starved granulosa cells activate caspase-3-like enzymes both prior to and after nuclear pyknosis, as revealed by a single-cell fluorescent caspase activity assay. These data, combined with previous observations regarding the role of homologs of the two other C. elegans cell death regulatory genes, ced-9 (Bcl-2 family members) and ced-3 (caspases), in atresia fully support the hypothesis that granulosa cell apoptosis is precisely coordinated by all three major arms of a cell death program conserved through evolution.
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PMID:Localization, regulation and possible consequences of apoptotic protease-activating factor-1 (Apaf-1) expression in granulosa cells of the mouse ovary. 1034 53

Nitric oxide (NO) is a potent inhibitor of apoptosis in many cell types, including hepatocytes. We and others have described NO-dependent decreases in caspase activity in cells undergoing apoptosis. However, previous work has not determined whether NO disrupts the proteolytic processing and thus the activation of pro-caspases. Here we report that NO suppresses proteolytic processing and activation of multiple pro-caspases in intact cells, including caspase-3 and caspase-8. We found that both exogenous NO as well as endogenously produced NO via adenoviral inducible NO synthase gene transfer protected hepatocytes from tumor necrosid factor (TNF) alpha plus actinomycin D (TNFalpha/ActD)-induced apoptosis. Affinity labeling with biotin-VAD-fmk of all active caspase species in TNFalpha-mediated apoptosis identified four newly labeled spots (activated caspases) present exclusively in TNFalpha/ActD-treated cells. Both NO and the caspase inhibitor, Ac-DEVD-CHO, prevented the appearance of the four newly labeled spots or active caspases. Immunoanalysis of affinity labeled caspases demonstrated that caspase-3 was the major effector caspase. Western blot analysis also identified the activation of caspase-8 in the TNFalpha/ActD-treated cells, and the activation was suppressed by NO. Furthermore, NO inhibited several other events associated with caspase activation in cells, including release of cytochrome c from mitochondria, decrease in mitochondrial transmembrane potential, and cleavage of poly(ADP-ribose) polymerase in TNFalpha/ActD-treated cells. These findings indicate the involvement of multiple caspases in TNFalpha-mediated apoptosis in hepatocytes and establish the capacity of NO to inhibit not only active caspases but also caspase activation.
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PMID:Nitric oxide suppresses apoptosis via interrupting caspase activation and mitochondrial dysfunction in cultured hepatocytes. 1035 93

We investigated the ability of caspases (cysteine proteases with aspartic acid specificity) to induce cytochrome c release from mitochondria. When Jurkat cells were induced to undergo apoptosis by Fas receptor ligation, cytochrome c was released from mitochondria, an event that was prevented by the caspase inhibitor, zVAD-fmk (zVal-Ala-Asp-CH2F). Purified caspase-8 triggered rapid cytochrome c release from isolated mitochondria in vitro. The effect was indirect, as the presence of cytosol was required, suggesting that caspase-8 cleaves and activates a cytosolic substrate, which in turn is able to induce cytochrome c release from mitochondria. The cytochrome c releasing activity was not blocked by caspase inhibition, but was antagonized by Bcl-2 or Bcl-xL. Caspase-8 and caspase-3 cleaved Bid, a proapoptotic Bcl-2 family member, which gains cytochrome c releasing activity in response to caspase cleavage. However, caspase-6 and caspase-7 did not cleave Bid, although they initiated cytochrome c release from mitochondria in the presence of cytosol. Thus, effector caspases may cleave and activate another cytosolic substrate (other than Bid), which then promotes cytochrome c release from mitochondria. Mitochondria significantly amplified the caspase-8 initiated DEVD-specific cleavage activity. Our data suggest that cytochrome c release, initiated by the action of caspases on a cytosolic substrates, may act to amplify a caspase cascade during apoptosis.
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PMID:Caspases induce cytochrome c release from mitochondria by activating cytosolic factors. 1036 79

The proteolytic caspase cascade plays a central role in the signaling and execution steps of apoptosis. This study investigated the activation of different caspases in apoptosis induced by MAL (a folding variant of human alpha-lactalbumin) isolated from human milk. Our results show that the caspase-3-like enzymes, and to a lesser extent the caspase-6-like enzymes, were activated in Jurkat and A549 cells exposed to MAL. Activated caspases subsequently cleaved several protein substrates, including PARP, lamin B, and alpha-fodrin. A broad-range caspase inhibitor, zVAD-fmk, blocked the caspase activation, the cleavage of proteins, and DNA fragmentation, indicating an important role for caspase activation in MAL-induced apoptosis. Since an antagonistic anti-CD95 receptor antibody, ZB4, did not influence the MAL-induced killing, we conclude that this process does not involve the CD95-mediated pathway. While MAL did not directly activate caspases in the cytosol, it colocalized with mitochondria and induced the release of cytochrome c. Thus, these results demonstrate that caspases are activated and involved in apoptosis induced by MAL and that direct interaction of MAL with mitochondria leads to the release of cytochrome c, suggesting that this release is an important step in the initiation and/or amplification of the caspase cascade in these cells.
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PMID:Protease activation in apoptosis induced by MAL. 1036 25

Polyamines are ubiquitous organic cations required for cell proliferation. However, some evidence suggested that their excessive accumulation can induce apoptosis. We show here that, in a post-nuclear extract from U937 cells, the addition of spermine triggers the death program, represented by cytochrome c exit from mitochondria, the dATP-dependent processing of pro-caspase-3 and the onset of caspase activity. Spermine is more effective than spermidine, whereas putrescine has no effect. Polyamine acetylation abolishes their pro-apoptotic power. These data demonstrate a direct mechanism responsible for polyamine toxicity and also suggest that an excessive elevation of free polyamines could be involved in the transduction of a death signal.
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PMID:Spermine triggers the activation of caspase-3 in a cell-free model of apoptosis. 1037 Nov 45

Human granulocyte-macrophage colony-stimulating factor fused to truncated diphtheria toxin (DT388-GM-CSF) sensitized wild-type and Bcl2-overexpressing HL60 human leukemia cells to intoxication by Ara-C based on proliferation and clonogenic assays. The toxin/drug combination showed dramatic synergistic toxicity with combination indices of < 0.1. Synergy was not seen with two other protein synthesis inhibiting drugs--ricin and cycloheximide nor with GMCSF alone. No changes in Ara-C incorporation into cellular DNA or cell cycle occupancy were seen. As compared to exposure to DT388-GM-CSF or Ara-C alone, co-treatment produced significant increases in cytosolic accumulation of cytochrome c, a higher percentage of cells with loss of mitochondrial membrane potential and an increase in reactive oxygen species and morphologic changes of apoptosis, and a greater induction of poly(ADP-ribose) polymerase (PARP) and DNA fragmentation factor 45 (DFF45) cleavage activities of caspase 3. Co-treatment did not significantly alter Bcl2, Bcl-xL, Bax or Fas receptor (FasR), but modestly increased Fas ligand (FasL) protein. These finding suggest that co-treatment with DT388-GM-CSF may lead to a lowered apoptotic threshold and clonogenic survival of human AML blasts due to Ara-C. These observations also suggest that clinical trials of combination therapy may be warranted in patients with AML.
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PMID:Diphtheria toxin fused to granulocyte-macrophage colony-stimulating factor and Ara-C exert synergistic toxicity against human AML HL-60 cells. 1037 46

We reported previously that singlet oxygen, generated by irradiation of rose bengal with visible light, induced apoptosis in human promyelocytic leukemia HL-60 cells. However, the mechanism of apoptosis caused by this reactive oxygen species is unclear. In this study, we demonstrate that singlet oxygen induced caspase-3 activation and Z-DEVD-FMK, a caspase-3 inhibitor, blocked apoptosis induction, while caspase-1 activity was not detectable and the caspase-1 inhibitor Z-YVAD-FMK had a very limited effect on apoptosis. This suggests that the activation of caspase-3 by singlet oxygen is essential for the commitment of cells to undergo apoptosis. Further studies showed that singlet oxygen induced an increase in caspase-8 activity and a reduction in mitochondrial cytochrome c. Time course analysis indicated that the cleavage of caspase-8 precedes that of caspase-3. In addition, blockade of caspase-8 by Z-IETD-FMK inhibited cleavage of pro-caspase-3 and prevented loss of mitochondrial cytochrome c. These results suggest that caspase-8 mediates caspase-3 activation and cytochrome c release during singlet oxygen-induced apoptosis in HL-60 cells.
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PMID:Caspase-8 mediates caspase-3 activation and cytochrome c release during singlet oxygen-induced apoptosis of HL-60 cells. 1038 34

We investigated the relationship between manganese superoxide dismutase (Mn-SOD) activity and apoptosis induced by anticancer drugs and radiation. Although the activity of copper, zinc-SOD did not differ greatly among 9 squamous cell carcinoma (SCC) cell lines (OSC-1 to OSC-9), the Mn-SOD activity did differ among the cell lines. The Mn-SOD activity was increased by treatments with 5-fluorouracil (5-FU), peplomycin and 137Cs, reaching plateau levels at 12 h after treatment and then decreasing gradually. When OSC-1 and OSC-3, and OSC-2 and OSC-4 were examined as representative cell lines with low and high Mn-SOD activity, respectively, the decrease was more prominent in OSC-1 and OSC-3 than in OSC-2 and OSC-4. The intracellular levels of superoxide and hydrogen peroxide (H2O2) were increased after treatment with the anticancer agents, and the increases were larger in OSC-1 and OSC-3 than in OSC-2 and OSC-4. The decrease of mitochondrial membrane potential (deltapsi(m)) by the anticancer agents was marked in OSC-1 and OSC-3. Correspondingly, the release of cytochrome c, the activation of caspase-3 and the cleavage of poly(ADP-ribose)polymerase were stronger in OSC-3 than in OSC-4. In addition, apoptosis induced by the anticancer agents was prominent in OSC-3, exhibiting a close relationship with the deltapsi(m) and the H2O2 level. These results indicate that Mn-SOD in SCC cells modulates apoptosis induction and the inactivation of Mn-SOD might be a promising strategy for SCC treatment.
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PMID:Manganese superoxide dismutase negatively regulates the induction of apoptosis by 5-fluorouracil, peplomycin and gamma-rays in squamous cell carcinoma cells. 1039 Oct 96


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