Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Programmed cell death involves the activation of caspase proteases that can mediate the cleavage of vital cytoskeletal proteins. We have recently reported that, in failing cardiac myocytes, caspase-3 activation is associated with a reduction in contractile performance. In this study we used a modified yeast two-hybrid system to screen for caspase-3 interacting proteins of the cardiac cytoskeleton. We identified ventricular essential myosin light chain (vMLC1) as a target for caspase-3. By sequencing and site-directed mutagenesis, a noncanonical cleavage site for caspase-3 was mapped to the C-terminal DFVE(135)G motif. We demonstrated that vMLC1 cleavage in failing myocardium in vivo is associated with a morphological disruption of the organized vMLC1 staining of sarcomeres, and with a reduction in myocyte contractile performance. Adenoviral gene transfer of the caspase inhibitor p35 in vivo prevented caspase-3 activation and vMLC1 cleavage, with positive impact on contractility. These data suggest that direct cleavage of vMLC1 by activated caspase-3 may contribute to depression of myocyte function by altering cross-bridge interaction between myosin and actin molecules. Therefore, activation of apoptotic pathways in the heart may lead to contractile dysfunction before cell death.
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PMID:Essential myosin light chain as a target for caspase-3 in failing myocardium. 1218 78

The apoptosome is a multiprotein complex comprising Apaf-1, cytochrome c, and caspase-9 that functions to activate caspase-3 downstream of mitochondria in response to apoptotic signals. Binding of cytochrome c and dATP to Apaf-1 in the cytosol leads to the assembly of a heptameric complex in which each Apaf-1 subunit is bound noncovalently to a procaspase-9 subunit via their respective CARD domains. Assembly of the apoptosome results in the proteolytic cleavage of procaspase-9 at the cleavage site PEPD(315) to yield the large (p35) and small (p12) caspase-9 subunits. In addition to the PEPD site, caspase-9 contains a caspase-3 cleavage site (DQLD(330)), which when cleaved, produces a smaller p10 subunit in which the NH(2)-terminal 15 amino acids of p12, including the XIAP BIR3 binding motif, are removed. Using purified proteins in a reconstituted reaction in vitro, we have assessed the relative impact of Asp(315) and Asp(330) cleavage on caspase-9 activity within the apoptosome. In addition, we characterized the effect of caspase-3 feedback cleavage of caspase-9 on the rate of caspase-3 activation, and the potential ramifications of Asp(330) cleavage on XIAP-mediated inhibition of the apoptosome. We have found that cleavage of procaspase-9 at Asp(330) to generate p35, p10 or p37, p10 forms resulted in a significant increase (up to 8-fold) in apoptosome activity compared with p35/p12. The significance of this increase was demonstrated by the near complete loss of apoptosome-mediated caspase-3 activity when a point mutant (D330A) of procaspase-9 was substituted for wild-type procaspase-9 in the apoptosome. In addition, cleavage at Asp(330) exposed a novel p10 NH(2)-terminal peptide motif (AISS) that retained the ability to mediate XIAP inhibition of caspase-9. Thus, whereas feedback cleavage of caspase-9 by caspase-3 significantly increases the activity of the apoptosome, it does little to attenuate its sensitivity to inhibition by XIAP.
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PMID:Regulation of the Apaf-1/caspase-9 apoptosome by caspase-3 and XIAP. 1250 11

In this study we report that the baculovirus p35 anti-apoptotic protein prevents cell death by quenching free radicals at a very upstream step in the apoptotic pathway. Mitochondria of activated rat peritoneal macrophages as well as Spodoptera frugiperda (Sf9) insect cells, following treatment with oxidants, H(2)O(2)/UVB irradiation, release cytochrome c followed by activation of caspase-3. Transfection of macrophages/Sf9 cells with a construct carrying the p35 gene under the CMV/HSP promoters resulted in p35 expression and consequent arrest of oxidative stress-induced apoptosis. p35 expression also inhibited cytochrome c release from the mitochondria of oxidant-exposed cells and blocked caspase-3 activation.
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PMID:Baculoviral p35 inhibits oxidant-induced activation of mitochondrial apoptotic pathway. 1289 47

Plants, animals, and several branches of unicellular eukaryotes use programmed cell death (PCD) for defense or developmental mechanisms. This argues for a common ancestral apoptotic system in eukaryotes. However, at the molecular level, very few regulatory proteins or protein domains have been identified as conserved across all eukaryotic PCD forms. A very important goal is to determine which molecular components may be used in the execution of PCD in plants, which have been conserved during evolution, and which are plant-specific. Using Arabidopsis thaliana, we have shown that UV radiation can induce apoptosis-like changes at the cellular level and that a UV experimental system is relevant to the study of PCD in plants. We report here that UV induction of PCD required light and that a protease cleaving the caspase substrate Asp-Glu-Val-Asp (DEVDase activity) was induced within 30 min and peaked at 1 h. This DEVDase appears to be related to animal caspases at the biochemical level, being insensitive to broad-range cysteine protease inhibitors. In addition, caspase-1 and caspase-3 inhibitors and the pan-caspase inhibitor p35 were able to suppress DNA fragmentation and cell death. These results suggest that a YVADase activity and an inducible DEVDase activity possibly mediate DNA fragmentation during plant PCD induced by UV overexposure. We also report that At-DAD1 and At-DAD2, the two A. thaliana homologs of Defender against Apoptotic Death-1, could suppress the onset of DNA fragmentation in A. thaliana, supporting an involvement of the endoplasmic reticulum in this form of the plant PCD pathway.
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PMID:Ultraviolet-C overexposure induces programmed cell death in Arabidopsis, which is mediated by caspase-like activities and which can be suppressed by caspase inhibitors, p35 and Defender against Apoptotic Death. 1457 11

Cyclin-dependent kinase 5 (Cdk5) and its regulatory subunit p35 are integral players in the proper development of the mammalian central nervous system. Proteolytic cleavage of p35 generates p25, leading to aberrant Cdk5 activation. The accumulation of p25 is implicated in several neurodegenerative diseases. In primary neurons, p25 causes apoptosis and tau hyperphosphorylation. Current mouse models expressing p25, however, fail to rigorously recapitulate these phenotypes in vivo. Here, we generated inducible transgenic mouse lines overexpressing p25 in the postnatal forebrain. Induction of p25 preferentially directed Cdk5 to pathological substrates. These animals exhibited neuronal loss in the cortex and hippocampus, accompanied by forebrain atrophy, astrogliosis, and caspase-3 activation. Endogenous tau was hyperphosphorylated at many epitopes, aggregated tau accumulated, and neurofibrillary pathology developed progressively in these animals. Our cumulative findings provide compelling evidence that in vivo deregulation of Cdk5 by p25 plays a causative role in neurodegeneration and the development of neurofibrillary pathology.
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PMID:Aberrant Cdk5 activation by p25 triggers pathological events leading to neurodegeneration and neurofibrillary tangles. 1464 73

Mutant copper/zinc superoxide dismutase (SOD1)-overexpressing transgenic mice, a mouse model for familial amyotrophic lateral sclerosis (ALS), provides an excellent resource for developing novel therapies for ALS. Several observations suggest that mitochondria-dependent apoptotic signaling, including caspase-9 activation, may play an important role in mutant SOD1-related neurodegeneration. To elucidate the role of caspase-9 in ALS, we examined the effects of an inhibitor of X chromosome-linked inhibitor of apoptosis (XIAP), a mammalian inhibitor of caspase-3, -7 and -9, and p35, a baculoviral broad caspase inhibitor that does not inhibit caspase-9. When expressed in spinal motor neurons of mutant SOD1 mice using transgenic techniques, XIAP attenuated disease progression without delaying onset. In contrast, p35 delayed onset without slowing disease progression. Moreover, caspase-9 was activated in spinal motor neurons of human ALS subjects. These data strongly suggest that caspase-9 plays a crucial role in disease progression of ALS and constitutes a promising therapeutic target.
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PMID:The crucial role of caspase-9 in the disease progression of a transgenic ALS mouse model. 1465 37

Cyclin-dependent kinases (CDKs) have recently raised considerable interest in view of their key role in the regulation of the cell cycle progression. In proliferating cells, distinct CDKs associated with specific cyclins coordinate in an orchestrated way the appropriate transition between different phases of the cell cycle. Mutations and/or aberrant expression of distinct CDKs and their regulatory components lead to uncontrolled proliferation and finally to carcinogenesis. However, in post-mitotic neurons, all CDKs with the exception of CDK5 are silent. CDK5, a proline-directed serine/threonine kinase exhibiting a close structural homology to the mitotic CDKs, binds to p35, the neuron-specific regulatory subunit of CDK5. CDK5 is very abundant in mature neurons and seems to regulate neurotransmitter release through phosphorylation and down-regulation of calcium channel activity. Therefore, the inhibition of CDKs in neurons after oxidative stress and in neurodegenerative disorders has a protective action. Selective CDKs inhibitors were developed as promising drugs for cancer therapy due to their ability to arrest cell cycle progression. The aim of this study was to compare the anti-proliferative effect of roscovitine (ROSC), a potent CDKs inhibitor, with that of cisplatin (CP) on human breast cancer MCF-7 cells. ROSC exerted stronger inhibitory effect on proliferation and cell cycle progression of MCF-7 than CP. Accumulation of G(2)/M arrested cells starting 6 h after onset of ROSC treatment coincided with a strong up-regulation of the p53. Reconstitution with caspase-3 sensitized MCF-7 cells to CP action. It implicates that ROSC inhibits more selectively and efficaciously the proliferation of human breast carcinoma cells.
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PMID:Dual action of cyclin-dependent kinase inhibitors: induction of cell cycle arrest and apoptosis. A comparison of the effects exerted by roscovitine and cisplatin. 1470 84

Caspases are responsible for a cascade of events controlling the disassembly of apoptotic cells. We now demonstrate that caspase-9 is activated at an early stage of apoptosis in epithelial cells and all its detectable, catalytically active large subunits (both the p35 and p37) are concentrated on cytokeratin fibrils. Immunolabeling of distinctive neoepitopes, exposed by cleavage of procaspase-9 at either Asp315 or Asp330, was co-localized on these fibrils with active caspase-3, caspase-cleaved cytokeratin-18, death-effector-domain containing DNA-binding protein and ubiquitin. Cytokeratin filaments may thus provide a scaffold whereby active subunits of caspase-9 can activate caspase-3 which, in turn, can activate more caspase-9 so forming an amplification loop to facilitate cleavage of cytokeratin-18, disruption of the cytoskeleton and the ensuing formation of cytoplasmic inclusions. These inclusions, formed from the collapse of fibrils, together with their associated components, also contain ubiquitinated proteins, vimentin, heat-shock protein 72, and tumor necrosis factor receptor type-1-associated death domain protein. Many of their constituents, including active caspases, remain sequestered within these inclusions, even after detergent treatment and isolation. Thus, such inclusions do not merely accumulate disrupted cytokeratins but also sequestrate potentially noxious proteins that could injure healthy neighboring cells.
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PMID:Intermediate filaments control the intracellular distribution of caspases during apoptosis. 1474 46

The apoptosome is a large caspase-activating ( approximately 700-1400 kDa) complex, which is assembled from Apaf-1 and caspase-9 when cytochrome c is released during mitochondrial-dependent apoptotic cell death. Apaf-1 the core scaffold protein is approximately 135 kDa and contains CARD (caspase recruitment domain), CED-4, and multiple (13) WD40 repeat domains, which can potentially interact with a variety of unknown regulatory proteins. To identify such proteins we activated THP.1 lysates with dATP/cytochrome c and used sucrose density centrifugation and affinity-based methods to purify the apoptosome for analysis by MALDI-TOF mass spectrometry. First, we used a glutathione S-transferase (GST) fusion protein (GST-casp9(1-130)) containing the CARD domain of caspase-9-(1-130), which binds to the CARD domain of Apaf-1 when it is in the apoptosome and blocks recruitment/activation of caspase-9. This affinity-purified apoptosome complex contained only Apaf-1XL and GST-casp9(1-130), demonstrating that the WD40 and CED-4 domains of Apaf-1 do not stably bind other cytosolic proteins. Next we used a monoclonal antibody to caspase-9 to immunopurify the native active apoptosome complex from cell lysates, containing negligible levels of cytochrome c, second mitochondria-derived activator of caspase (Smac), or Omi/HtrA2. This apoptosome complex exhibited low caspase-processing activity and contained four stably associated proteins, namely Apaf-1, pro-p35/34 forms of caspase-9, pro-p20 forms of caspase-3, X-linked inhibitor of apoptosis (XIAP), and cytochrome c, which was only bound transiently to the complex. However, in lysates containing Smac and Omi/HtrA2, the caspase-processing activity of the purified apoptosome complex increased 6-8-fold and contained only Apaf-1 and the p35/p34-processed subunits of caspase-9. During apoptosis, Smac, Omi/HtrA2, and cytochrome c are released simultaneously from mitochondria, and thus it is likely that the functional apoptosome complex in apoptotic cells consists primarily of Apaf-1 and processed caspase-9.
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PMID:Pro-apoptotic proteins released from the mitochondria regulate the protein composition and caspase-processing activity of the native Apaf-1/caspase-9 apoptosome complex. 1499 23

Apoptosis protease-activating factor-1 (Apaf-1), which plays a central role in the formation of the apoptosome, is absent or poorly expressed (because of a transcriptional silencing by methylation) in a substantial percentage of metastatic melanomas and melanoma cell lines, which are unable to activate caspase-9 and execute the mitochondrial pathway of apoptosis. We studied cisplatin-induced apoptosis of the Apaf-1-positive human metastatic Me665/2/21 melanoma cells. Our results indicate that caspase-7 is already processed in still-adhering cells and such activation, contrary to the common view, precedes caspase-3 processing. As expected by the cytochrome c release into the cytosol, caspase-9 is processed to active forms (p37 and p35), along with a yet-unidentified p28. Interestingly, we also demonstrate a remarkable loss of Apaf-1 protein, along with the appearance of a related immunoreactive fragment of approximate, equals 26 kDa; such proteolytic degradation proves to be a caspase-3/-7-mediated event. Our data also indicate that the inhibition afforded by ac-DEVD-CHO on several components (i.e., caspase-3/-7 and caspase-9 activities), and Apaf-1 proteolytic degradation, does not significantly abrogate either the apoptotic morphology or the cleavage of canonical targets, such as poly(ADP-ribose) polymerase (PARP) and lamin B. These results suggest that caspase-3 and caspase-7 are dispensable for the execution of apoptosis and, in our cellular model, the point of no return could be out of the mitochondrial cascade.
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PMID:Cisplatin-induced apoptosis in melanoma cells: role of caspase-3 and caspase-7 in Apaf-1 proteolytic cleavage and in execution of the degradative phases. 1503 20


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