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)

In the present study, a newly synthesized benzofuran lignan 4-formyl-2-(4-hydroxy-3methoxyphenyl)-5-(2-methoxycarbonyethyl)-7-methoxy-benzo [b] furan (ERJT-12) was tested for its antiproliferative activity on human tumor cells. The related mechanisms were also investigated. In vitro growth inhibitory effects of ERJT-12 on various cancer cell lines were determined by MTT assay. Cell cycle distribution and apoptosis were detected by flow cytometry. The integrity of DNA was assessed by agarose gel electrophoresis. Activation of Caspase-3/7 and Caspase-6 was measured by colorimetric assay. The expressions of cell cycle proteins cell divide cycle 25c (Cdc25c), cyclin dependent kinase 1 (CDK1), CyclinB1 and apoptosis-related proteins Bax and Bcl-2 were detected by Western blotting. MTT assay showed that ERJT-12 inhibited the proliferation of several cancer cell lines including multidrug resistant cells. MCF-7 cells were markedly arrested at gap2/mitosis (G2/M) phase after treatment with ERJT-12 and progressed into apoptosis. The increased activities of Caspase-3/7 and Caspase-6 in MCF-7 cells were observed. The expression of CyclinB1 was down-regulated. The activities of Cdc25c and CDK1 protein were suppressed and Bcl-2 protein was phosphorylated. ERJT-12 displays potent antiproliferative activity towards cancer cells through suppressing cell cycle proteins, arresting cell cycle at G2/M phase and inducing apoptosis. It might be a novel candidate for cancer therapy.
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PMID:[Induction of G2 /M phase arrest and apoptosis of MCF-7 cells by novel benzofuran lignan via suppressing cell cycle proteins]. 1850 39

Caspase-3, -6 and -7 cleave many proteins at specific sites to induce apoptosis. Their recognition of the P5 position in substrates has been investigated by kinetics, modeling and crystallography. Caspase-3 and -6 recognize P5 in pentapeptides as shown by enzyme activity data and interactions observed in the crystal structure of caspase-3/LDESD and in a model for caspase-6. In caspase-3 the P5 main-chain was anchored by interactions with Ser209 in loop-3 and the P5 Leu side-chain interacted with Phe250 and Phe252 in loop-4 consistent with 50% increased hydrolysis of LDEVD relative to DEVD. Caspase-6 formed similar interactions and showed a preference for polar P5 in QDEVD likely due to interactions with polar Lys265 and hydrophobic Phe263 in loop-4. Caspase-7 exhibited no preference for P5 residue in agreement with the absence of P5 interactions in the caspase-7/LDESD crystal structure. Initiator caspase-8, with Pro in the P5-anchoring position and no loop-4, had only 20% activity on tested pentapeptides relative to DEVD. Therefore, caspases-3 and -6 bind P5 using critical loop-3 anchoring Ser/Thr and loop-4 side-chain interactions, while caspase-7 and -8 lack P5-binding residues.
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PMID:Structural basis for executioner caspase recognition of P5 position in substrates. 1878 Jan 84

Na(+)/H(+) exchanger-1 (NHE-1) overexpression is associated with carcinogenesis and is an attractive target for intervention. We report that the chemopreventive agent resveratrol (RSV) downregulates NHE-1 in a caspase-dependent manner without inducing cell death. Resveratrol triggered early activation of caspase 3 and late activation of caspase 6, which were not inter-dependent. Whereas, caspase 3 activation appeared to be a direct effect of resveratrol, caspase 6 activation was mediated via intracellular hydrogen peroxide production and iron. Moreover, downregulation of NHE-1 expression was a function of resveratrol-induced repression of NHE-1 gene promoter activity. RNAi-mediated silencing of caspase 3 or 6 blocked the effect of resveratrol on NHE-1 expression, however the effect on NHE-1 promoter was observed at different phases of promoter repression with caspase 3 controlling the early phase (4-12 h) and caspase 6 regulating the late phase (12-24 h). Scavenging hydrogen peroxide or iron only reversed the late phase of resveratrol-induced NHE-1 promoter repression. Finally, an AP2 binding region within NHE-1 gene promoter was identified as the target of resveratrol. Collectively, these data could explain the anti-cancer activity of resveratrol in the light of the association of increased NHE-1 expression with carcinogenesis.
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PMID:Resveratrol regulates the expression of NHE-1 by repressing its promoter activity: critical involvement of intracellular H2O2 and caspases 3 and 6 in the absence of cell death. 1895 95

Human disc-large (hDlg) is a scaffold protein critical for the maintenance of cell polarity and adhesion. hDlg is a component of the p38gamma MAP kinase pathway, which is important for the adaptation of mammalian cells to changes in environmental osmolarity. Here we report a strong decrease in the levels of hDlg protein in the human epithelial cell line HeLa when exposed to osmotic shock. This is independent of the phosphorylation state of hDlg, is prevented by preincubating the cell with the caspase inhibitor z-VAD and is part of the apoptotic process triggered by cellular stress. Although, both caspase 3 and caspase 6 are strongly activated by osmotic shock, the time course of caspase 6 activation parallels hDlg degradation, suggesting that this caspase may be responsible for the proteolysis. Mutating hDlg Asp747 to Ala abolishes caspase-induced cleavage, but does not affect the early stage of apoptosis or cell attachment. Our findings show that osmotic stress triggers hDlg degradation through a mechanism different from the one mediated by proteasomes, and we identify hDlg as a caspase substrate during the apoptotic process, although its proteolysis may not be implicated in the progression of early apoptosis.
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PMID:Proteolysis of the tumour suppressor hDlg in response to osmotic stress is mediated by caspases and independent of phosphorylation. 1905 65

Caspase-6 (Casp6) is a short pro-domain caspase that is activated early in Alzheimer disease, yet, little is known on the mechanism of activation of this caspase. In this study, critical proteolytic processing events required for Casp6 activation in vitro and in vivo were evaluated by site directed mutagenesis of the D23 pro-domain, and D179 and D193 linker processing sites. We found that (1) Casp6 was self-processed and activated in vitro and in vivo, (2) uncleavable Casp6 possessed low activity in vitro but not in vivo, (3) the pro-domain of Casp6 entirely prevented self-processing and activation in vivo but not in vitro, (4) removal of the pro-domain promoted Casp6 activation, (5) cleavage at either D179 or D193 was sufficient to generate activity in vitro and in vivo, and (6) Casp6 activity did not induce cell death in HEK293T cells. We conclude that the Casp6 is activated through proteolytic cleavage, as are the effector Caspase-3 and -7. However, unlike other effector caspases, Casp6 can be entirely self-activated and its activation does not necessarily induce cell death.
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PMID:Self-activation of Caspase-6 in vitro and in vivo: Caspase-6 activation does not induce cell death in HEK293T cells. 1913 98

Naturally occurring axonal pruning and neuronal cell death help to sculpt neuronal connections during development, but their mechanistic basis remains poorly understood. Here we report that beta-amyloid precursor protein (APP) and death receptor 6 (DR6, also known as TNFRSF21) activate a widespread caspase-dependent self-destruction program. DR6 is broadly expressed by developing neurons, and is required for normal cell body death and axonal pruning both in vivo and after trophic-factor deprivation in vitro. Unlike neuronal cell body apoptosis, which requires caspase 3, we show that axonal degeneration requires caspase 6, which is activated in a punctate pattern that parallels the pattern of axonal fragmentation. DR6 is activated locally by an inactive surface ligand(s) that is released in an active form after trophic-factor deprivation, and we identify APP as a DR6 ligand. Trophic-factor deprivation triggers the shedding of surface APP in a beta-secretase (BACE)-dependent manner. Loss- and gain-of-function studies support a model in which a cleaved amino-terminal fragment of APP (N-APP) binds DR6 and triggers degeneration. Genetic support is provided by a common neuromuscular junction phenotype in mutant mice. Our results indicate that APP and DR6 are components of a neuronal self-destruction pathway, and suggest that an extracellular fragment of APP, acting via DR6 and caspase 6, contributes to Alzheimer's disease.
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PMID:APP binds DR6 to trigger axon pruning and neuron death via distinct caspases. 1922 11

Infection with parvovirus B19 (B19) may induce apoptosis resulting in anemia, acute fulminant liver failure, placental insufficiency and myocarditis. Apoptosis has been attributed to proapoptotic activity of the non-structural viral protein NS1, which is known to trigger a signaling cascade eventually leading to activation of caspases. In several cell types apoptosis was found to be paralleled by profound cytosolic acidification, which may be secondary to inhibition of the Na+/H+ exchanger. The acidification has been considered to support the activation of pH sensitive caspases and endonucleases. However, nothing is known about the effect of NS1 on Na+/H+ exchanger activity and cytosolic pH. The present study thus explored whether NS1 expression affects cytosolic pH (pHi) and Na+-dependent realkalinization (DeltapHi) following acidification by an ammonium pulse. According to FACS analysis, overexpression of NS1 in RXR-10SW cells led within 72 hours to activation of caspase 3 and DNA fragmentation. NS1 overexpression resulted within 24 hours in a significant decline of pHi from 6.93 +/- 0.03 (n = 6) to 6.78 +/- 0.04 (n = 7), and to a significant decrease of DeltapHi from 0.159 +/- 0.017 (n = 6) to 0.039 +/- 0.004, (n = 7). The decrease of pHi and of DeltapHi following NS1 expression could be significantly blunted by inhibition of caspase 3 with zVAD. Western blot analysis revealed degradation of NHE1 following NS1 expression. In vitro, caspase 3, but not caspase 6, caspase 7 and caspase 8 degraded NHE1 protein of cell lysates. In conclusion, overexpression of NS1 triggers a signaling cascade eventually leading to activation of caspase 3 and subsequent degradation of NHE1. The effect contributes to cytosolic acidification which may in turn favor activation of caspases and endonucleases and thus participate in the pathophysiology of B19-infection.
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PMID:Inhibition of Na+/H+ exchanger activity by parvovirus B19 protein NS1. 1925 16

Stimulation of transformed bovine brain endothelial cells (TBBEC) with LPS leads to apoptosis while human microvessel endothelial cells (HMEC) need the presence of cycloheximide (CHX) with LPS to induce apoptosis. To investigate the molecular mechanism of LPS-induced apoptosis in HMEC or TBBEC, we analyzed the involvement of MAPK and PI3K in TBBEC and HMEC. LPS-induced apoptosis in TBBEC was hallmarked by the activation of caspase 3, caspase 6, and caspase 8 after the stimulation of LPS, followed by poly(ADP-ribose) polymerase cleavage and lactate dehydrogenase release. We also observed DNA cleavage determined by TUNEL staining in TBBEC treated with LPS. Herbimycin A, a tyrosine kinase inhibitor, and SP600125, a JNK inhibitor, suppressed the activation of caspases and lactate dehydrogenase release. Moreover, a PI3K inhibitor (LY294002) suppressed activation of caspases and combined treatment with both SP600125 and LY294002 completely inhibited the activation of caspases. These results suggest that the JNK signaling pathway through the tyrosine kinase and PI3K pathways is involved in the induction of apoptosis in LPS-treated TBBEC. On the other hand, we observed sustained JNK activation in HMEC treated with LPS and CHX, and neither ERK1/2 nor AKT were activated. The addition of SP600125 suppressed phosphorylation of JNK and the activation of caspase 3 in HMEC treated with LPS and CHX. These results suggest that JNK plays an important role in the induction of apoptosis in endothelial cells.
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PMID:Lipopolysaccharide-induced apoptosis in transformed bovine brain endothelial cells and human dermal microvessel endothelial cells: the role of JNK. 1945 25

The valosin-containing protein (p97) is a ubiquitin-dependent ATPase that plays central roles in ubiquitin proteasome system (UPS)-mediated protein degradation pathways. p97 has been recently identified as a putative substrate of active Caspase-6 (Casp6) in primary human neurons. Since Casp6 is activated in mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients' brains, the targeting of p97 by Casp6 may represent an important step that leads to UPS impairment in AD. Here, we show that p97 is a Casp6 substrate in vitro and in vivo. Casp6 cleavage of recombinant p97 generated two N-terminal fragments of 28 and 20 kDa, which were not generated by the other two effector caspases, Caspase-3 and Caspase-7. ATP binding to the D1 ATPase ring of p97 reduced the susceptibility of the N-domain to caspase-mediated proteolysis. Mass spectrometric analysis identified VAPD(179) as a Casp6 cleavage site within p97's N-domain. An anti-neoepitope serum immunohistochemically detected p97 cleaved at VAPD(179) in the cytoplasm of the cell soma and neurites of hippocampal neurons in MCI and AD. Overexpression of p97 (1-179) fragment, representing p97 cleaved at D179, impaired the degradation of model substrates in the ubiquitin-fusion degradation and the N-end rule pathways, and destabilized endogenous p97. Collectively, these results show that p97 is cleaved by Casp6 in AD and suggest p97 cleavage as an important mechanism for UPS impairment.
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PMID:Identification of Caspase-6-mediated processing of the valosin containing protein (p97) in Alzheimer's disease: a novel link to dysfunction in ubiquitin proteasome system-mediated protein degradation. 2042 71

Dimeric effectors caspase 3 and caspase 7 are activated by initiator caspase processing. In this study, we report the crystal structures of effector caspase 6 (CASP6) zymogen and N-Acetyl-Val-Glu-Ile-Asp-al-inhibited CASP6. Both of these forms of CASP6 have a dimeric structure, and in CASP6 zymogen the intersubunit cleavage site (190)TEVD(193) is well structured and inserts into the active site. This positions residue Asp 193 to be easily attacked by the catalytic residue Cys 163. We demonstrate biochemically that intramolecular cleavage at Asp 193 is a prerequisite for CASP6 self-activation and that this activation mechanism is dependent on the length of the L2 loop. Our results indicate that CASP6 can be activated and regulated through intramolecular self-cleavage.
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PMID:Crystal structures of human caspase 6 reveal a new mechanism for intramolecular cleavage self-activation. 2089 Mar 11


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