Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.60 (caspase-7)
 920 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of cleaved caspase-3, cleaved caspase-7 and specific product of caspase-dependent Poly (ADP-Ribose) Polymerase (PARP) cleavage have been examined by immunohistochemistry in seven human medulloblastomas. Cleaved caspase-3 and cleaved PARP expression parallels apoptosis as revealed with classical morphological criteria and with the method of in situ end-labelling of nuclear DNA fragmentation. Cleaved PARP co-localizes cleaved caspase-3 in the majority of tumors and areas thus indicating that caspase-3 is a major effector caspase leading to apoptosis in these tumors. Yet cleaved caspase-7 was also expressed in a small number of cells in four of seven tumors, but was the predominant caspase associated with cleaved PARP in one medulloblastoma. These findings indicate that effector caspase-3 and -7 may act in association, although caspase-7 may be exceptionally dominant in selected tumors.
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PMID:Cleaved caspase-3, caspase-7 and poly (ADP-ribose) polymerase are complementarily but differentially expressed in human medulloblastomas. 1140 64

During cellular apoptosis, retinoblastoma protein (RB) is subjected to cleavage near the carboxyl terminus by a caspase-3-like protease. In addition, an heretofore unidentified protease cleaves RB internally, generating fragments of 68 and 48 kDa. Internal cleavage abrogates the ability of RB to associate with E2F. To investigate the mechanism of RB internal cleavage, we developed and employed an in vitro cleavage assay. Incubation of in vitro translated (35)S-RB with apoptotic cell extracts led to RB cleavage at the C-terminus, followed by internal cleavage. The caspase peptide inhibitors z-VAD-FMK or z-DEVD-FMK blocked both cleavage events. Rapid C-terminal and internal cleavage were also observed when recombinant caspase-3 was added to (35)S-RB. Moreover, when caspase-3 was added to nonapoptotic cell extract, efficient internal cleavage of cellular RB was observed. Caspase-mediated internal cleavage occurred following RB residue aspartate(349) in the sequence DSID(349). This sequence is consistent with a DXXD recognition motif for caspase-3-like enzymes. Interestingly, we also observed RB internal cleavage in caspase-3-deficient MCF-7 cells, indicating that other caspases are capable of cleaving RB internally. Indeed, caspase-7, a member of the caspase-3 subfamily, was found to cleave (35)S-RB at both the carboxyl terminus, and following aspartate(349). By contrast, caspases that are not members of the caspase-3 subfamily failed to cleave RB. Taken together, our findings demonstrate that during apoptosis, a caspase-3-like protease is responsible for degradation and functional inactivation of RB by cleaving the protein internally following aspartate(349).
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PMID:Sequential two-step cleavage of the retinoblastoma protein by caspase-3/-7 during etoposide-induced apoptosis. 1142 Jul 4

The endoplasmic reticulum (ER) is the site of assembly of polypeptide chains destined for secretion or routing into various subcellular compartments. It also regulates cellular responses to stress and intracellular Ca(2+) levels. A variety of toxic insults can result in ER stress that ultimately leads to apoptosis. Apoptosis is initiated by the activation of members of the caspase family and serves as a central mechanism in the cell death process. The present study was carried out to determine the role of caspases in triggering ER stress-induced cell death. Treatment of cells with ER stress inducers such as brefeldin-A or thapsigargin induces the expression of caspase-12 protein and also leads to translocation of cytosolic caspase-7 to the ER surface. Caspase-12, like most other members of the caspase family, requires cleavage of the prodomain to activate its proapoptotic form. Caspase-7 associates with caspase-12 and cleaves the prodomain to generate active caspase-12, resulting in increased cell death. We propose that any cellular insult that causes prolonged ER stress may induce apoptosis through caspase-7-mediated caspase-12 activation. The data underscore the involvement of ER and caspases associated with it in the ER stress-induced apoptotic process.
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PMID:Coupling endoplasmic reticulum stress to the cell death program. Mechanism of caspase activation. 1144 53

The ubiquitin-proteasome pathway plays a critical role in the degradation of cellular proteins and cell cycle control. Dysregulating the degradation of such proteins should have profound effects on tumor growth and causes cells to undergo apoptosis. The aims of this study are to evaluate the ubiquitin-proteasome pathway in gastric cancer and the potential role of pharmacological inhibition of proteasome on induction of apoptosis in gastric cancer cells. Gastric cancer cell lines AGS (p53 wild-type) and MKN-28 (p53 mutant) were treated with proteasome inhibitor MG132. The results showed that MG132 inhibited cell proliferation in AGS and MKN-28 cells in a time- and dose-dependent manner. The inhibition of cell proliferation was caused by apoptosis which was also time- and dose-dependent. AGS cells were more responsive to MG132 than MKN-28 cells. Induction of apoptosis was preceded by the activation of caspase-3, as measured by a colorimetric caspase-3 cellular activity and Western blotting of the cleavage of caspase-3 and its substrate PARP. Activation of caspase-7 was also exhibited. In addition, z-VAD-fmk, a broad spectrum caspase inhibitor, reversed apoptosis induced by MG132 in AGS and MKN28 cells. Although z-DEVD-fmk, a specific caspase-3 inhibitor, suppressed MG132-induced apoptosis in MKN28 cells, it only partially rescued the apoptotic effect in AGS cells. Caspase-3 activation was the result of release of cytochrome c from mitochondria into the cytosol, as a consequence of upregulation of bax. There were overexpressions of all the proteasome-related proteins p53, p21(waf1) and p27(kip1) at 4 hr after proteasome inhibition which was identified by the accumulation of ubiquitin-tagged proteins. This was accompanied by accumulation of cells at G(1) phase. Our present study suggests that inhibition of proteasome function in gastric cancer cells induces apoptosis and proteasomal inhibitors have potential use as novel anticancer drugs in gastric cancer.
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PMID:Inhibition of proteasome function induced apoptosis in gastric cancer. 1147 51

Rana catesbeiana ribonuclease (RC-RNase) and onconase were proven to own anti-tumor activity. While molecular determinants of onconase-induced cell death have become more explicit, the RC-RNase-induced death pathway remains presently unknown. Here we demonstrated that RC-RNase-induced molecular cascades in caspase-3-deficient MCF-7 cells did not include activation of initiation caspase-8 and -9. Cleavage timing suggested that procaspase-2 and -6 might be processed by active caspase-7 in MCF-7 cells. Caspase-7 was also responsible for cleavage of the poly(ADP-ribose) polymerase. Furthermore, we reported that overexpression of Bcl-X(L) could raise the survival rates of MCF-7 cells treated with RC-RNase and onconase.
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PMID:Caspase activation in response to cytotoxic Rana catesbeiana ribonuclease in MCF-7 cells. 1151 56

Molecular mechanisms of apoptosis may participate in motor neuron degeneration produced by mutant superoxide dismutase-1 (mSOD1), the only proven cause of amyotrophic lateral sclerosis (ALS). Consistent with this, here we show that the proapoptotic protein Bax translocates from the cytosol to the mitochondria, whereas cytochrome c translocates from the mitochondria to the cytosol in spinal cords of transgenic mSOD1 mice during the progression of the disease. Concomitantly, caspase-9 is activated in the spinal cord of transgenic mSOD1 mice. Only in end-stage transgenic mSOD1 mice is the downstream caspase-7 activated and the inhibitor of apoptosis, XIAP, cleaved. These results indicate a sequential recruitment of molecular elements of the mitochondrial-dependent apoptotic pathway in transgenic mSOD1 mice. We also provide immunohistochemical evidence that cytochrome c translocation occurs in the spinal cord of sporadic ALS patients. Collectively, these data suggest that the mitochondrial-dependent apoptotic pathway may contribute to the demise of motor neurons in ALS and that targeting key molecules of this cascade may prove to be neuroprotective.
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PMID:Recruitment of the mitochondrial-dependent apoptotic pathway in amyotrophic lateral sclerosis. 1151 46

Max is the central component of the Myc/Max/Mad network of transcription factors that regulate growth, differentiation and apoptosis. Whereas the Myc and Mad genes and proteins are highly regulated, Max expression is constitutive and no post-translational regulation is known. We have found that Max is targeted during Fas-induced apoptosis. Max is first dephosphorylated and subsequently cleaved by caspases. Two specific cleavage sites for caspases in Max were identified, one at IEVE(10) decreasing S and one at SAFD(135) decreasing G near the C-terminus, which are cleaved in vitro by caspase-5 and caspase-7 respectively. Mutational analysis indicates that both sites are also used in vivo. Thus Max represents the first caspase-5 substrate. The unusual cleavage after a glutamic acid residue is observed only with full-length, DNA-binding competent Max protein but not with corresponding peptides, suggesting that structural determinants might be important for this activity. Furthermore, cleavage by caspase-5 is inhibited by the protein kinase CK2-mediated phosphorylation of Max at Ser-11, a previously mapped phosphorylation site in vivo. These findings suggest that Fas-mediated dephosphorylation of Max is required for cleavage by caspase-5. The modifications that occur on Max in response to Fas signalling affect the DNA-binding activity of Max/Max homodimers. Taken together, our findings uncover three distinct processes, namely dephosphorylation and cleavage by caspase-5 and caspase-7, that target Max during Fas-mediated apoptosis, suggesting the regulation of the Myc/Max/Mad network through its central component.
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PMID:Targeting of the transcription factor Max during apoptosis: phosphorylation-regulated cleavage by caspase-5 at an unusual glutamic acid residue in position P1. 1153 31

The protein kinase PKR is a major player in the cellular antiviral response, acting mainly by phosphorylation of the alpha-subunit of the eukaryotic translation initiation factor 2 (eIF2-alpha) to block de novo protein synthesis. PKR activation requires binding of double-stranded RNA or PACT/RAX proteins to its regulatory domain. Since several reports have demonstrated that translation is inhibited in apoptosis, we investigated whether PKR and eIF2-alpha phosphorylation contribute to this process. We show that PKR is proteolysed and that eIF2-alpha is phosphorylated at the early stages of apoptosis induced by various stimuli. Both events coincide with the onset of caspase activity and are prevented by caspase inhibitors. Using site-directed mutagenesis we show that PKR is specifically proteolysed at Asp(251) during cellular apoptosis. This site is cleaved in vitro by recombinant caspase-3, caspase-7, and caspase-8 and not by the proinflammatory caspase-1 and caspase-11. The released kinase domain efficiently phosphorylates eIF2-alpha at the cognate Ser(51) residue, and its overexpression in mammalian cells impairs the translation of its own mRNA and of reporter mRNAs. Our results demonstrate a new and caspase-dependent activation mode for PKR, leading to eIF2-alpha phosphorylation and translation inhibition in apoptosis.
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PMID:Translation inhibition in apoptosis: caspase-dependent PKR activation and eIF2-alpha phosphorylation. 1155 40

Survivin is a member of the inhibitor of apoptosis (IAP) gene family, containing a single baculovirus IAP repeat (BIR) and no RING finger, that is expressed in many human cancers. Although it has been proposed to be involved in mitotic and cytokinetic processes, its functional subcellular distribution in the cytoplasm and nucleus, and its binding to centrosomes, spindle fibers, and centromeres in relation to these processes, is not fully resolved. We have analyzed the localization of Survivin in normal (Detroit 551, IMR-90) and tumor-derived (HeLa, Saos-2) cell lines, and found that it does colocalize with centrosomes in the cytoplasm during interphase, then moves to centromeres during mitosis, and finally localizes to the midbody spindle fibers during telophase. However, Taxol, a popular microtubule stabilizing agent that is frequently used in the study of these processes, severely disrupted the localization of Survivin. Taxol treatment of cells promoted extensive relocalization of Survivin with alpha-tubulin on microtubules during either interphase or mitosis. Survivin antisense oligonucleotide markedly sensitized HeLa cells to cell death induced by agents acting at the level of cell surface receptor (Fas pathway) or at the level of mitochondria (etoposide). HeLa cell death induced by Survivin antisense oligonucleotide could be partially complemented by Deterin, the Drosophila homolog of Survivin (Jones et al. [2000] J. Biol. Chem. 275:22157-22166). Reciprocally, a chimera of the Deterin BIR domain and Survivin C-terminus could rescue Drosophila Kc cells from death induced by transfection of a human caspase-7-expressing plasmid. These results indicate common components of Survivin and Deterin antiapoptotic action in the vertebrate and invertebrate phyla.
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PMID:Participation of Survivin in mitotic and apoptotic activities of normal and tumor-derived cells. 1157 50

Hepatitis C virus (HCV) infection is a major cause of liver disease characterized by inflammation, cell damage, and fibrotic reactions of hepatocytes. Apoptosis has been implicated in the pathogenesis, although it is unclear whether proteases of the caspase family as the central executioners of apoptosis are involved and how caspase activation contributes to liver injury. In the present study, we measured the activation of effector caspases in liver biopsy specimens of patients with chronic HCV infection. The activation of caspase-3, caspase-7, and cleavage of poly(ADP-ribose)polymerase (PARP), a specific caspase substrate, were measured by immunohistochemistry and Western blot analysis by using antibodies that selectively detect the active truncated, but not the inactive precursor forms of the caspases and PARP. We found that caspase activation was considerably elevated in liver lobules of HCV patients in comparison to normal controls. Interestingly, the immunoreactive cells did yet not reveal an overt apoptotic morphology. The extent of caspase activation correlated significantly with the disease grade, i.e., necroinflammatory activity. In contrast, no correlation was observed with other surrogate markers such as serum transaminases and viral load. In biopsy specimens with low activity (grade 0) 7.7% of the hepatocytes revealed caspase-3 activation, whereas 20.9% of the cells stained positively in grade 3. Thus, our results suggest that caspase activation is involved in HCV-associated liver injury. Moreover, measurement of caspase activity may represent a reliable marker for the early detection of liver damage, which may open up new diagnostic and therapeutic strategies in HCV infection.
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PMID:Caspase activation correlates with the degree of inflammatory liver injury in chronic hepatitis C virus infection. 1158 73


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