Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.22.61 (caspase-8)
 6,833 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Apoptosis appears to be the death mechanism of pericyte loss observed in diabetic retinopathy. We have previously shown that advanced glycation end-products (AGE-MGX) induce apoptosis of retinal pericytes in culture associated with diacylglycerol (DAG)/ceramide production. In the present study, we investigated possible caspase involvement in this process. Bovine retinal pericytes (BRP) were cultured with AGE-MGX and apoptosis examined after annexin V staining. Effects of peptidic inhibitors of caspases were determined on DAG/ceramide production and apoptosis. Pan-caspase inhibitor z-VAD-fmk (50 microM) was able to inhibit both DAG/ceramide production and apoptosis, whereas caspase-3-like inhibitor z-DEVD-fmk (50 microM) or caspase-9 inhibitor z-LEHD-fmk (50 microM) was only active on apoptosis. This differential effect strongly suggests involvement of initiator caspase(s) upstream and effector caspase(s) downstream DAG/ceramide production in AGE-mediated apoptosis. Pericyte treatment with caspase-8 inhibitor z-IETD-fmk (50 microM) did not protect cells against AGE-induced apoptosis and we failed to detect caspase-8 in pericytes by immunoblotting assay. Interestingly, one inhibitor of caspase-10 and related caspases z-AEVD-fmk (50 microM) inhibited both AGE-MGX-induced apoptosis and DAG/ceramide formation in pericytes. Cleavage of caspase-10 precursor into its active subunits was demonstrated by immunoblotting assay in pericytes incubated with AGE-MGX. These results strongly suggest that caspase-10, but not caspase-8, might be involved in the early phase of AGE-induced pericyte apoptosis, in contrast to caspase-9 and -3-like enzymes involved after DAG/ceramide production. This finding may provide new therapeutic perspectives for early treatment in diabetic retinopathy.
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PMID:Involvement of caspase-10 in advanced glycation end-product-induced apoptosis of bovine retinal pericytes in culture. 1527 46

Evaluating the functional consequences of prostate apoptosis response gene-4 (par-4) expression in CD95-induced apoptosis of neoplastic lymphocytes, we demonstrate that par-4 increases apoptosis by upregulating the CD95 receptor on the cell surface and--with a concomitant decrease of the FLICE-like inhibitory protein (FLIP)--by promoting cleavage of the initiator caspases-8 and -10. This results in an enforced activation of the executioner caspases-6, -7, and -3 as well as in an activation of the mitochondrial pathway. Upon inhibition of caspase-8, overexpression of par-4 enables Jurkat cells to maintain a higher sensitivity to CD95-induced apoptosis by downregulating cIAP-2 and XIAP and by enforcing activation of the initiator caspase-10 as well as of the executioner caspases-6, -7, and -3.
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PMID:Prostate apoptosis response gene-4 sensitizes neoplastic lymphocytes to CD95-induced apoptosis. 1531 56

To investigate the effects of di(2-ethylhexyl) phthalate (DEHP) on gene expression in rat testis, 6-week-old male Sprague-Dawley rats were given a single oral dose of 20 or 2000 mg/kg and euthanized 3, 6, 24, or 72 h thereafter. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells were significantly increased in the testis at 24 and 72 h after the exposure to 2000 mg/kg of DEHP. On cDNA microarray analysis, in addition to apoptosis-related genes, genes associated with atrophy, APEX nuclease, MutS homologue (E. coli), testosterone-repressed-prostatic-message-2 (TRPM-2), connective tissue growth factor, collagen alpha 2 type V, and cell adhesion kinase were differentially expressed. To investigate the relationship between histopathological alteration and gene expression, we selected genes associated with apoptosis and analyzed their expression by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). With 20 mg/kg of DEHP treatment, bcl-2, key gene related to apoptosis, was increased. Up-regulation of bcl-2, inhibitor of Apaf-1/caspase-9/caspase-2 cascade of apoptosis, may be related to the fact that no morphological apoptotic change was induced after dosing of 20 mg/kg DEHP. With 2000 mg/kg of DEHP treatment, the apoptotic activator cascade, Fas/FasL, FADD/caspase-8/caspase-3 cascade, and Apaf-1/caspase-9/caspase-2 cascade were increased and bcl-2 was decreased. Thus, these gene regulations might lead the cells into apoptosis in the case of high exposure to DEHP. In contrast, FADD/caspase-10/caspase-6 cascade and caspase-11/caspase-3 cascade were not increased. These results indicate that the cascades of FADD/caspase-10/caspase-6 and caspase-11/caspase-3 are not related to apoptosis with DEHP treatment.
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PMID:Gene expression analysis of the rat testis after treatment with di(2-ethylhexyl) phthalate using cDNA microarray and real-time RT-PCR. 1547 63

Beta1-integrin protects keratinocyte stem cells (KSC) from cell-detachment apoptosis ('anoikis'). Here we show that caspase-8 active protein is detected in both young transit amplifying (TA) cells and TA cells, but not in KSC. On suspension, caspases are activated earlier in young TA than in KSC, whereas anti-beta1-integrin neutralizing antibody accelerates caspase activation in both KSC and young TA. Caspases 8 and 10 are the first caspases to be activated whereas caspase-8 inhibitor zIETD-fmk delays the activation of Bid, caspase-9 and caspase-3. However, the caspase-9 inhibitor zLEDH-fmk does not block the activation of caspase-8, Bid, caspase-10 and caspase-3. Moreover, caspase-8, but not caspase-9 inhibitor partially prevents keratinocyte anoikis. As FLIP inhibits caspase-8 processing, we retrovirally infected HaCaT keratinocytes with c-FLIP(L). Anti-beta1-integrin fails to activate caspase-8, Bid, caspase-9 and to induce the release of cytochrome c in c-FLIP(L) overexpressing keratinocytes. Finally, overexpression of c-FLIP(L) partially prevents anoikis in both suspended and anti-beta1 integrin-treated cells. Taken together, these results indicate that the extrinsic apoptotic pathway triggered by caspase-8 predominates in keratinocyte anoikis. However, the release of cytochrome c and the later activation of caspase-9 seem to suggest that the intrinsic mitochondrial pathway may intervene as a positive feedback loop of caspase activation.
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PMID:FLICE/caspase-8 activation triggers anoikis induced by beta1-integrin blockade in human keratinocytes. 1550 84

FADD is an adaptor protein that transmits apoptotic signals from death receptors such as Fas to downstream initiator caspases in mammals. We have identified and characterized the Xenopus orthologue of mammalian FADD (xFADD). xFADD contains both a death effector domain (DED) and a death domain (DD) that are structurally homologous to those of mammalian FADD. We observed xFADD binding to Xenopus caspase-8 and caspase-10 as well as to human caspase-8 and Fas through interactions with their homophilic DED and DD domains. When over-expressed, xFADD was also able to induce apoptosis in wild-type mouse embryonic fibroblasts (MEF), but not in caspase-8-deficient MEF cells. In contrast, DED-deficient xFADD (xFADDdn) acted as a dominant-negative mutant and prevented Fas-mediated apoptosis in mammalian cell lines. These results indicate that xFADD transmits apoptotic signals from Fas to caspase-8. Furthermore, we found that transgenic animals expressing xFADD in the developing heart or eye under the control of tissue-specific promoters show abnormal phenotypes. Taken together, these results suggest that xFADD can substitute functionally for its mammalian homologue in death receptor-mediated apoptosis, and we suggest that xFADD functions as a pro-apoptotic adaptor molecule in frogs. Thus, the structural and functional similarities between xFADD and mammalian FADD provide evidence that the apoptotic pathways are evolutionally conserved across vertebrate species.
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PMID:The adaptor molecule FADD from Xenopus laevis demonstrates evolutionary conservation of its pro-apoptotic activity. 1556 56

In this study, we showed the existence of a positive correlation between the amount of human immunodeficiency virus-type 1 (HIV-1) RNA in HIV-1 seropositive subjects and the plasma levels of TRAIL. Since it has been previously demonstrated that HIV-1 Tat protein up-regulates the expression of TRAIL in monocytic cells whereas tat-expressing lymphoid cells are more resistant to TRAIL cytotoxicity, we next investigated the effect of Tat on the expression/activity of both apical caspase-8 and -10, which play a key role in mediating the initial phases of apoptosis by TRAIL, and c-FLIP. Jurkat lymphoblastoid human T cell lines stably transfected with a plasmid expressing wild-type (HIV-1) tat gene showed normal levels of caspase-8 but significantly decreased levels of caspase-10 at both mRNA and protein levels with respect to Jurkat transfected with the control plasmid or with a mutated (cys22) non-functional tat cDNA. A significant decrease of caspase-10 expression/activity was also observed in transient transfection experiments with plasmid carrying tat cDNA. Moreover, c-FLIP(L) and c-FLIP(S) isoforms were up-regulated in tat-expressing cells at both mRNA and protein level in comparison with control cells. Taken together, these results provide a molecular basis to explain the resistance of tat-expressing Jurkat cells to apoptosis induced by TRAIL and, possibly, to other death-inducing ligands.
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PMID:HIV-1 Tat protein concomitantly down-regulates apical caspase-10 and up-regulates c-FLIP in lymphoid T cells: a potential molecular mechanism to escape TRAIL cytotoxicity. 1557 81

Apoptosis, or programmed cell death, is perturbed in many cancers. We tested the hypothesis that coding polymorphisms of the death receptor 4 (DR4), caspase-8 (CASP8), and caspase-10 (CASP10) genes might act as low-penetrance breast cancer genes. Single-nucleotide polymorphisms (SNPs) of these genes were genotyped in a series of 999 breast cancer case patients and 996 control subjects from Sheffield, U.K., and in a second, independent U.K. population of 2192 case patients and 2262 control subjects from East Anglia. In the Sheffield study, the rare H allele of CASP8, D302H, was associated with a reduced risk of breast cancer in a dose-dependent manner (P(trend) = .007). Furthermore, the CASP8 D302H association, but not that of the other CASP8 SNPs examined (T21914C, G50121A, and G50358A), was replicated in the East Anglian study. The combined adjusted odds ratios for breast cancer were 0.83 (95% confidence interval [CI] = 0.74 to 0.94) for the DH heterozygote and 0.58 (95% CI = 0.39 to 0.88) for the HH homozygote (P(trend) = .0002, adjusted for study). The reproducible, dose-dependent association of CASP8 D302H with breast cancer indicates the potential importance of inherited variation in the apoptosis pathway in breast cancer susceptibility.
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PMID:Association of a common variant of the CASP8 gene with reduced risk of breast cancer. 1599 55

TRAIL can induce apoptosis in melanoma cells and thus may offer new hope for melanoma therapy. However, many melanoma cells are resistant to TRAIL. To examine molecular mechanisms in cell resistance, we analyzed TRAIL-induced DISC in TRAIL-sensitive melanoma cells and showed that apoptosis-initiating caspase-8 and caspase-10 were recruited to the DISC where they became activated through autocatalytical cleavage, leading to apoptosis through cleavage of downstream substrates such as caspase-3 and DFF45. In TRAIL-resistant melanoma cells, however, c-FLIP proteins were recruited to the DISC, resulting in the inhibition of caspase-8 and caspase-10 cleavage in the DISC. Both calmodulin-dependent protein kinase II (CaMKII) protein and enzymatic activity were upregulated in resistant cells and CaMKII inhibitor KN-93 downregulated expression of c-FLIP proteins, thus sensitizing resistant cells to TRAIL-induced apoptosis. Transfection of CaMKII cDNA in sensitive melanoma cells resulted in cell resistance to TRAIL, where transfection of CaMKII dominant-negative cDNA in resistant cells restored TRAIL sensitivity in cells. These results indicate that the CaMKII-mediated pathway for c-FLIP upregulation protects melanoma cells from TRAIL-induced apoptosis and targeting this pathway may provide novel therapeutic strategies in treatment of melanomas.
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PMID:Inhibition of CaMKII-mediated c-FLIP expression sensitizes malignant melanoma cells to TRAIL-induced apoptosis. 1570 89

Although signaling by death receptors involves the recruitment of common components into their death-inducing signaling complexes (DISCs), apoptosis susceptibility of various tumor cells to each individual receptor differs quite dramatically. Recently it was shown that, besides caspase-8, caspase-10 is also recruited to the DISCs, but its function in death receptor signaling remains unknown. Here we show that expression of caspase-10 sensitizes MCF-7 breast carcinoma cells to TRAIL- but not tumor necrosis factor (TNF)-induced apoptosis. This sensitization is most obvious at low TRAIL concentrations or when apoptosis is assessed at early time points. Caspase-10-mediated sensitization for TRAIL-induced apoptosis appears to be dependent on caspase-3, as expression of caspase-10 in MCF-7/casp-3 cells but not in caspase-3-deficient MCF-7 cells overcomes TRAIL resistance. Interestingly, neutralization of TRAIL receptor 2 (TRAIL-R2), but not TRAIL-R1, impaired apoptosis in a caspase-10-dependent manner, indicating that caspase-10 enhances TRAIL-R2-induced cell death. Furthermore, whereas processing of caspase-10 was delayed in TNF-treated cells, TRAIL triggered a very rapid activation of caspase-10 and -3. Therefore, we propose a model in which caspase-10 is a crucial component during TRAIL-mediated apoptosis that in addition actively requires caspase-3. This might be especially important in systems where only low TRAIL concentrations are supplied that are not sufficient for the fast recruitment of caspase-8 to the DISC.
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PMID:Caspase-10 sensitizes breast carcinoma cells to TRAIL-induced but not tumor necrosis factor-induced apoptosis in a caspase-3-dependent manner. 1576 84

In contrast to caspase-8, controversy exists as to the ability of caspase-10 to mediate apoptosis in response to FasL. Herein, we have shown activation of caspase-10, -3, and -7 as well as B cell lymphoma-2-interacting domain (Bid) cleavage and cytochrome c release in caspase-8-deficient Jurkat (I9-2) cells treated with FasL. Apoptosis was clearly induced as illustrated by nuclear and DNA fragmentation. These events were inhibited by benzyloxycarbonyl-VAD-fluoromethyl ketone, a broad spectrum caspase inhibitor, indicating that caspases were functionally and actively involved. Benzyloxycarbonyl-AEVD-fluoromethyl ketone, a caspase-10 inhibitor, had a comparable effect. FasL-induced cell death was not completely abolished by caspase inhibitors in agreement with the existence of a cytotoxic caspase-independent pathway. In subpopulations of I9-2 cells displaying distinct caspase-10 expression levels, cell sensitivity to FasL correlated with caspase-10 expression. A robust caspase activation, Bid cleavage, and DNA fragmentation were observed in cells with high caspase-10 levels but not in those with low levels. In vitro, caspase-10, as well as caspase-8, could cleave Bid to generate active truncated Bid (p15). Altogether, our data strongly suggest that caspase-10 can serve as an initiator caspase in Fas signaling leading to Bid processing, caspase cascade activation, and apoptosis.
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PMID:Caspase-10 triggers Bid cleavage and caspase cascade activation in FasL-induced apoptosis. 1577 77


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