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)

Recent genetic and biochemical studies have implicated cysteine-dependent aspartate-directed proteases (caspases) in the active phase of apoptosis. In the present study, three complementary techniques were utilized to follow caspase activation during the course of etoposide-induced apoptosis in HL-60 human leukemia cells. Immunoblotting revealed that levels of procaspase-2 did not change during etoposide-induced apoptosis, whereas levels of procaspase-3 diminished markedly 2-3 h after etoposide addition. At the same time, cytosolic peptidase activities that cleaved DEVD-aminotrifluoromethylcoumarin and VEID-aminomethylcoumarin increased 100- and 20-fold, respectively; but there was only a 1. 5-fold increase in YVAD-aminotrifluoromethylcoumarin cleavage activity. Affinity labeling with N-(Nalpha-benzyloxycarbonylglutamyl-Nepsilon-biotin yllysyl)aspartic acid [(2,6-dimethylbenzoyl)oxy]methyl ketone indicated that multiple active caspase species sequentially appeared in the cytosol during the first 6 h after the addition of etoposide. Analysis on one- and two-dimensional gels revealed that two species comigrated with caspase-6 and three comigrated with active caspase-3 species, suggesting that several splice or modification variants of these enzymes are active during apoptosis. Polypeptides that comigrate with the cytosolic caspases were also labeled in nuclei of apoptotic HL-60 cells. These results not only indicate that etoposide-induced apoptosis in HL-60 cells is accompanied by the selective activation of multiple caspases in cytosol and nuclei, but also suggest that other caspase precursors such as procaspase-2 are present but not activated during apoptosis.
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PMID:Activation of multiple interleukin-1beta converting enzyme homologues in cytosol and nuclei of HL-60 cells during etoposide-induced apoptosis. 905 43

Previous studies have shown that K562 chronic myelogenous leukemia cells are resistant to induction of apoptosis by a variety of agents, including the topoisomerase II (topo II) poison etoposide, when examined 4 to 24 hours after treatment with an initiating stimulus. In the present study, the responses of K562 cells and apoptosis-proficient HL-60 acute myelomonocytic leukemia cells to etoposide were compared, with particular emphasis on determining the long-term fate of the cells. When cells were treated with varying concentrations of etoposide for 1 hour and subsequently plated in soft agar, the two cell lines displayed similar sensitivities, with a 90% reduction in colony formation at 5 to 10 mu mol/L etoposide. After treatment with 17 mu mol/L etoposide for 1 hour, cleavage of the caspase substrate poly(ADP-ribose) polymerase (PARP), DNA fragmentation, and apoptotic morphological changes were evident in HL-60 cells in less than 6 hours. After the same treatment, K562 cells arrested in G2 phase of the cell cycle but otherwise appeared normal for 3 to 4 days before developing similar apoptotic changes. When the etoposide dose was increased to 68 mu mol/L, apoptotic changes were evident in HL-60 cells after 2 to 3 hours, whereas the same changes were observed in K562 cells after 24 to 48 hours. This delay in the development of apoptotic changes in K562 cells was accompanied by delayed release of cytochrome c to the cytosol and delayed appearance of peptidase activity that cleaved the fluorogenic substrates Asp-Glu-Val-Asp-aminotrifluoromethylcoumarin (DEVD-AFC) and Val-Glu-Ile-Asp-aminomethylcoumarin (VEID-AMC) as well as an altered spectrum of active caspases that were affinity labeled with N-(Nalpha-benzyloxycarbonylglutamyl-Nepsilon-biotin yllysyl) aspartic acid [(2,6-dimethylbenzoyl)oxy]methyl ketone [z-EK(bio)D-aomk]. On the other hand, the activation of caspase-3 under cell-free conditions occurred with indistinguishable kinetics in cytosol prepared from the two cell lines. Collectively, these results suggest that a delay in the signaling cascade upstream of cytochrome c release and caspase activation leads to a long latent period before the active phase of apoptosis is initiated in etoposide-treated K562 cells. Once the active phase of apoptosis is initiated, the spectrum and subcellular distribution of active caspase species differ between HL-60 and K562 cells, but a similar proportion of cells are ultimately killed in both cell lines.
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PMID:Comparison of caspase activation and subcellular localization in HL-60 and K562 cells undergoing etoposide-induced apoptosis. 937 39

Granzyme B (GzmB) is a neutral serine protease found in cytotoxic lymphocytes; this enzyme is critically involved in delivering the rapid apoptotic signal to susceptible target cells. GzmB has been difficult to study and has not yet been produced in non-mammalian systems because of the complex processing events that are thought to be required for its activation. In this report, we have successfully produced fully active, soluble recombinant GzmB (rGzmB) in a yeast-based system by fusing GzmB cDNA in frame with yeast alpha-factor cDNA, using the yeast KEX2 signal peptidase to release the processed enzyme into the supernatant of yeast cultures. We expressed the proenzyme form of GzmB as well and determined that pro-GzmB is efficiently converted to its active form by the cysteine proteinase dipeptidyl peptidase I. The fully processed enzyme was able to hydrolyze the synthetic substrate N-t-butyloxycarbonyl-L-alanyl-L-alanyl-L-aspartyl (Boc-Ala-Ala-Asp) thiobenzyl ester with a kcat of 17 s-1 and catalytic efficiency kcat/Km of 181,237 M-1 S-1; the recombinant enzyme is therefore at least twice as active as purified native GzmB. In addition, the recombinant enzyme hydrolyzes Boc-Ala-Ala-Met thiobenzyl ester with a kcat of 3.2 S-1 and a catalytic efficiency kcat/Km of 65,306 M-1 S-1. Purified rGzmB can also cleave the putative substrate caspase-3 into its signature p20/p10 forms. Unlike caspases, rGzmB is not sensitive to inhibition by several peptide-based inhibitors, including Ac-DEVD-CHO, Ac-YVAD-CMK, and ZIETD-FMK, as well as Zn2+ (a known inhibitor of caspase-3). Structural studies of rGzmB may allow us to better understand the substrate specificity of this enzyme and to design better inhibitors.
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PMID:Production of fully active recombinant murine granzyme B in yeast. 943 Jul 5

A tumor-suppressor gene, p16(INK4), which is deleted or mutated in tumors, regulates cell-cycle progression through a G(1)-S restriction point by inhibiting CDK4(CDK6)/cyclin-D-mediated phosphorylation of pRb. We have found that ectopic p16(INK4) expression increased cellular sensitivity of human non-small-cell-lung-cancer (NSCLC) A549 cells to a selective growth-inhibitory effect induced by the topoisomerase-I inhibitor 11, 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxy camptothecin (CPT-11) in vitro. In this study, we observed enhanced apoptosis characterized by DNA fragmentation in A549 cells transfected with p16(INK4) cDNA (A549/p16-1) and treated with CPT-11. This apoptosis was suppressed by the inhibitor of interleukin-1beta-converting enzyme (ICE/caspase-1) or ICE-like proteases, Z-Asp-CH2-DCB, as determined by DNA fragmentation and proteolytic cleavage of poly(ADP-ribose) polymerase, a natural substrate for CPP32/caspase-3. In A549/p16-1 cells, cytosolic peptidase activities that cleaved Z-DEVD-7-amino-4-trifluoromethylcoumarin increased during CPT-11-induced apoptosis and were suppressed by a highly specific caspase-3 and caspase-3-like inhibitor, Z-DEVD-fluoromethylketone. These findings indicate that p16(INK) is positively involved in the activation pathway of the caspase-3 induced by CPT-11. The increased delay in S-phase progression and subsequent induction of apoptosis were observed in CPT-11-treated A549/p16-1 cells on the basis of DNA histograms. Specific down-regulation of the cyclin-A protein level in A549/p16-1 cells was observed after CPT-11-treatment, whereas cyclin B, cdk2, and cdc2 protein levels were unaffected. These results suggest that ectopic p16(INK4) expression inappropriately decreases cyclin A and thereby terminates CPT-11-induced G(2)/M accumulation, which is followed by increased apoptosis in p16(INK4)-expressing A549 cells.
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PMID:Ectopic p16(ink4) expression enhances CPT-11-induced apoptosis through increased delay in S-phase progression in human non-small-cell-lung-cancer cells. 1073 46

Cysteine peptidase inhibitor genes (ICP) of the chagasin family have been identified in protozoan (Leishmania mexicana and Trypanosoma brucei) and bacterial (Pseudomonas aeruginosa) pathogens. The encoded proteins have low sequence identities with each other and no significant identity with cystatins or other known cysteine peptidase inhibitors. Recombinant forms of each ICP inhibit protozoan and mammalian clan CA, family C1 cysteine peptidases but do not inhibit the clan CD cysteine peptidase caspase 3, the serine peptidase trypsin or the aspartic peptidases pepsin and thrombin. The functional homology between ICPs implies a common evolutionary origin for these bacterial and protozoal proteins.
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PMID:Functional conservation of a natural cysteine peptidase inhibitor in protozoan and bacterial pathogens. 1272 89

Identification of relevant substrates is essential for elucidation of in vivo functions of peptidases. The recent availability of the complete genome sequences of many eukaryotic organisms holds the promise of identifying specific peptidase substrates by systematic proteome analyses in combination with computer-based screening of genome databases. Currently available proteomics and bioinformatics tools are not sufficient for reliable endopeptidase substrate predictions. To address these shortcomings the bioinformatics tool 'PEPS' (Prediction of Endopeptidase Substrates) has been developed and is presented here. PEPS uses individual rule-based endopeptidase cleavage site scoring matrices (CSSM). The efficiency of PEPS in predicting putative caspase 3, cathepsin B and cathepsin L cleavage sites is demonstrated in comparison to established algorithms. Mortalin, a member of the heat shock protein family HSP70, was identified by PEPS as a putative cathepsin L substrate. Comparative proteome analyses of cathepsin L-deficient and wild-type mouse fibroblasts showed that mortalin is enriched in the absence of cathepsin L. These results indicate that CSSM/PEPS can correctly predict relevant peptidase substrates.
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PMID:Toward computer-based cleavage site prediction of cysteine endopeptidases. 1288 57

Lysosomes are fundamental for cell growth, and thus inhibition of the lysosomal function often leads to cell death. L-Leucyl-L-leucine methyl ester (LeuLeuOMe) is a lysosomotropic agent that induces apoptosis of certain immune cells. LeuLeuOMe is taken up through receptor-mediated endocytosis, and then converted into (LeuLeu)n-OMe (n>3) by dipeptidyl peptidase I (DPPI) in lysosomes, which reportedly causes rupture of the lysosomes and DNA fragmentation. In this study we examined how lysosomal damage causes DNA fragmentation in LeuLeuOMe-treated HL-60 cells. When acridine orange was employed to monitor lysosomal membrane integrity, orange or red granular fluorescence was seen in normal cells. In contrast, LeuLeuOMe-treated cells showed orange, yellow or green cellular fluorescence all over the cytoplasm, suggesting that LeuLeuOMe induced a loss of lysosomal membrane integrity. The loss was inhibited by a DPPI inhibitor, GlyPheCHN2 (GFCHN2), but not by a caspase-3 inhibitor, Ac-DEVD-CHO, indicating that a condensation product was responsible for the loss. LeuLeuOMe also induced the activation of caspase-3-like protease and DNA fragmentation, both of which were inhibited by either GFCHN2 or Ac-DEVD-CHO. Therefore, the activation of caspase-3-like protease links the loss of lysosomal membrane integrity to DNA fragmentation during apoptosis induced by LeuLeuOMe.
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PMID:Mechanism of apoptosis induced by a lysosomotropic agent, L-Leucyl-L-Leucine methyl ester. 1463 38

A Chlorella powder was screened using 52 in vitro assay systems for enzyme activity, receptor binding, cellular cytokine release, and B and T cell proliferation. The screening revealed a very potent inhibition of human protein tyrosine phosphatase (PTP) activity of CD45 and PTP1C with 50% inhibitory concentration (IC(50)) values of 0.678 and 1.56 microg/mL, respectively. It also showed a moderate inhibition of other PTPs, including PTP1B (IC(50) = 65.3 microg/mL) and T-cell-PTP (114 microg/mL). Other inhibitory activities and their IC(50) values included inhibition of the human matrix metalloproteinases (MMPs) MMP-1 (127 microg/mL), MMP-3 (185 microg/mL), MMP-7 (18.1 microg/mL), and MMP-9 (237 microg/mL) and the human peptidase caspases caspase 1 (300 microg/mL), caspase 3 (203 microg/mL), caspase 6 (301 microg/mL), caspase 7 (291 microg/mL), and caspase 8 (261 microg/mL), as well as release of the cytokines interleukin (IL)-1 (44.9 microg/mL), IL-2 (14.8 microg/mL), IL-4 (49.2 microg/mL), IL-6 (34.7 microg/mL), interferon-gamma (31.6 microg/mL), and tumor necrosis factor-alpha (11 microg/mL) from human peripheral blood mononuclear cells. Chlorella also inhibited B cell proliferation (16.6 microg/mL) in mouse splenocytes and T cell proliferation (54.2 microg/mL) in mouse thymocytes. The binding of a phorbol ester, phorbol 12,13-dibutyrate, to its receptors was also inhibited by Chlorella with an IC(50) of 152 microg/mL. These results reveal potential pharmacological activities that, if confirmed by in vivo studies, might be exploited for the prevention or treatment of several serious pathologies, including inflammatory disease and cancer.
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PMID:Effects of chlorella on activities of protein tyrosine phosphatases, matrix metalloproteinases, caspases, cytokine release, B and T cell proliferations, and phorbol ester receptor binding. 1529 60

Aflatoxins (AF) are contaminants of improperly stored foods; they are potent genotoxic and carcinogenic compounds, exerting their effects through damage to DNA. They can also induce mutations that increase oxidative damage. The goal of this study was to evaluate the possibility that a third mechanism could be involved in the carcinogenic action of aflatoxins, namely, direct binding to key enzymes involved in the regulatory pathways of the cell cycle, thereby modulating enzyme functionality. The 20S constitutive and immunoproteasome peptidase and proteolytic activities were assayed in the presence of aflatoxins B1, G1 and M1. All three toxins activated multiple peptidase activities of the proteasome. Aflatoxin (AF) M1 was the most potent activator of proteasome activity, while the constitutive 20S proteasome was specifically stimulated by AFG1. Furthermore, the effects of AFB1 on cultured hepatoma cells were investigated and the various proteasomal activities determined with cell lysates were differently affected. Taking into account the key role of the proteasome in cellular defense against oxidative stress, the carbonyl group content and the activities of antioxidant enzymes in cell lysates were analyzed. The proapoptotic effect of AFB1 was also investigated by measuring caspase-3 activity and cellular levels of p27 and IkappaBalpha.
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PMID:Binding of aflatoxins to the 20S proteasome: effects on enzyme functionality and implications for oxidative stress and apoptosis. 1721 55

A strategy involving the use of a self-immolative linker has been investigated for the chemiluminescent sensing of proteases. The reactive linker enabled the release of a 1,2-dioxetane light precursor. As a proof of principle, caspase-3, a key peptidase involved in apoptosis has been targeted. An in vitro assay has been carried out and proved the decomposition of the linker and the selectivity for caspase-3.
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PMID:Chemiluminescent probe for the in vitro detection of protease activity. 1793 76


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