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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA fragmentation during apoptosis is mediated by a heterodimeric protein complex, DFF45/ICAD and DFF40/CAD/CPAN. Purified DFF40 alone possesses intrinsic nuclease activity that is inhibited by its association with DFF45. The proteolytic cleavage of DFF45 by caspase-3 frees the DFF40 subunit to function as a nuclease. In the course of identifying factors that stimulate DFF activity, we have isolated a nuclear factor and identified it as the high mobility group protein 2 (HMG2). We found that bacterially expressed HMG2 is able to enhance the nuclease activity of DFF. As HMG2 has DNA bending activity (6), our data suggest that HMG proteins may augment DNA fragmentation during apoptosis through changes in chromosome structure.
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PMID:Identification of the nuclear factor HMG2 as an activator for DFF nuclease activity. 978 91

The DNA fragmentation factor (DFF) is composed of two subunits, the 40-kDa caspase-3-activated nuclease (DFF40/CAD) and its 45-kDa inhibitor (DFF45/ICAD). During apoptosis, DFF-40/CAD is activated by caspase-3-mediated cleavage of DFF45/ICAD. Mutational analysis of DFF40/CAD revealed that DFF40/CAD is composed of a C-terminal catalytic domain and an N-terminal regulatory domain. Deletion of the catalytic domain (residues 290-345) abrogated the caspase-3-induced nuclease activity of DFF40/CAD but not its ability to interact with DFF45/ICAD. Conversely, removal of the regulatory domain (residues 1-83) yielded a constitutively active DFF40/CAD nuclease that neither bound to its inhibitor nor required caspase-3 for activation. Amino acid alignment revealed that the regulatory domain of DFF40/CAD has homology to the N-terminal region of mammalian and Drosophila DFF45/ICAD and CIDE-N, a regulatory domain previously identified in pro-apoptotic CIDE proteins. Mutational analysis of the N-terminal region revealed mutants with diminished nuclease activity but with intact ability to bind DFF45/ICAD. Thus, CIDE-N represents a new type of domain that is associated with the regulation of the apoptosis/DNA fragmentation pathway.
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PMID:Identification of regulatory and catalytic domains in the apoptosis nuclease DFF40/CAD. 986 40

Apoptosis is defined by several unique morphological nuclear changes, such as chromatin condensation and nuclear fragmentation. These changes are triggered by the activation of a family of cysteine proteases called caspases, and caspase-activated DNase (CAD/DFF40) and lamin protease (caspase-6) have been implicated in some of these changes. CAD/DFF40 induces chromatin condensation in purified nuclei, but distinct caspase-activated factor(s) may be responsible for chromatin condensation. Here we use an in vitro system to identify a new nuclear factor, designated Acinus, which induces apoptotic chromatin condensation after cleavage by caspase-3 without inducing DNA fragmentation. Immunodepletion experiments showed that Acinus is essential for apoptotic chromatin condensation in vitro, and an antisense study revealed that Acinus is also important in the induction of apoptotic chromatin condensation in cells.
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PMID:Acinus is a caspase-3-activated protein required for apoptotic chromatin condensation. 1049 18

Caspase-3 initiates apoptotic DNA fragmentation by proteolytically inactivating DFF45 (DNA fragmentation factor-45)/ICAD (inhibitor of caspase-activated DNase), which releases active DFF40/CAD (caspase-activated DNase), the inhibitor's associated endonuclease. Here, we examined whether other apoptotic proteinases initiated DNA fragmentation via DFF45/ICAD inactivation. In a cell-free assay, caspases-3, -6, -7, -8, and granzyme B initiated benzoyloxycarbonyl-Asp-Glu-Val-Asp (DEVD) cleaving caspase activity, DFF45/ICAD inactivation, and DNA fragmentation, but calpain and cathepsin D failed to initiate these events. Strikingly, only the DEVD cleaving caspases, caspase-3 and caspase-7, inactivated DFF45/ICAD and promoted DNA fragmentation in an in vitro DFF40/CAD assay, suggesting that granzyme B, caspase-6, and caspase-8 promote DFF45/ICAD inactivation and DNA fragmentation indirectly by activating caspase-3 and/or caspase-7. In vitro, however, caspase-3 inactivated DFF45/ICAD and promoted DNA fragmentation more effectively than caspase-7 and endogenous levels of caspase-7 failed to inactivate DFF45/ICAD in caspase-3 null MCF7 cells and extracts. Together, these data suggest that caspase-3 is the primary inactivator of DFF45/ICAD and therefore the primary activator of apoptotic DNA fragmentation.
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PMID:Caspase-3 is the primary activator of apoptotic DNA fragmentation via DNA fragmentation factor-45/inhibitor of caspase-activated DNase inactivation. 1052 51

Degradation of nuclear DNA into nucleosomal units is one of the hallmarks of apoptotic cell death. It occurs in response to various apoptotic stimuli in a wide variety of cell types. Molecular characterization of this process identified a specific DNase (CAD, caspase-activated DNase) that cleaves chromosomal DNA in a caspase-dependent manner. CAD is synthesized with the help of ICAD (inhibitor of CAD), which works as a specific chaperone for CAD and is found complexed with ICAD in proliferating cells. When cells are induced to undergo apoptosis, caspases-in particular caspase 3-cleave ICAD to dissociate the CAD:ICAD complex, allowing CAD to cleave chromosomal DNA. Cells that lack ICAD or that express caspase-resistant mutant ICAD thus do not show DNA fragmentation during apoptosis, although they do exhibit some other features of apoptosis and die. In this review, the molecular mechanism of and the physiological roles played by apoptotic DNA fragmentation will be discussed.
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PMID:Apoptotic DNA fragmentation. 1073 46

Granzyme B (GzmB) is a component of cytotoxic lymphocyte granules that can rapidly initiate apoptosis in target cells. While several procaspases are cleaved and activated by GzmB, the absolute requirement of caspase activation for GzmB-induced apoptosis is controversial. In this report, we demonstrate that GzmB can initiate apoptosis in the absence of caspase-3 activity by directly cleaving DFF45/ICAD to liberate activated DFF40/CAD. DFF45/ICAD cleavage occurs less efficiently in cells that lack caspase-3 activity, suggesting that the caspases normally amplify the GzmB death signal. DFF45/ICAD-deficient mouse embryo fibroblasts are partially resistant to GzmB-induced death, demonstrating the biological importance of DFF45/ICAD for GzmB-mediated apoptosis.
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PMID:DFF45/ICAD can be directly processed by granzyme B during the induction of apoptosis. 1089 62

Here we review the different apoptotic DNases. From a functional point of view, DNases implicated in apoptosis may be classified into three groups: the Ca2+/Mg2+ endonucleases, the Mg2+-endonucleases, and the cation-independent endonucleases. The first group includes DNase I which has no specificity for the linker region, DNase gamma which has some homology with DNase I, and other DNases which cleave DNA in the linker region. Both DNase I and DNase gamma have been cloned. The other nucleases of this category have dispersed molecular weights. Their sequences are unknown and it is difficult to determine their role(s) in apoptosis. It seems that different pathways are present and that these nucleases may be activated either by caspases or serine proteases. The caspase 3 activated DNase (CAD, CPAN, or DFF40) belongs to the Mg2+-dependent endonucleases. DNase II belongs to the third group of acid endonucleases or cation-independent DNases. We have shown the involvement of DNase II in lens cell differentiation. Recently, the molecular structure of two different enzymes has been elucidated, one of which has a signal peptide and appears to be secreted. The other, called L-DNase II, is an intracellular protein having two enzymatic activities; in its native form, it is an anti-protease, and after posttranslational modification, it becomes a nuclease.
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PMID:DNases and apoptosis. 1101 79

Respiratory syncytial virus (RSV) infection induced programmed cell death or apoptosis in the cultured lung epithelial cell line, A549. The apoptotic cells underwent multiple changes, including fragmentation and degradation of genomic DNA, consistent with the activation of the DNA fragmentation factor or caspase-activated DNase (DFF or CAD). The infection led to activation of FasL; however, a transdominant mutant of FAS-downstream death domain protein, FADD, did not inhibit apoptosis. Similarly, modest activation of cytoplasmic apoptotic caspases, caspase-3 and -8, were observed; however, only a specific inhibitor of caspases-3 inhibited apoptosis, while an inhibitor of caspase-8 had little effect. No activation of caspase-9 and -10, indicators of the mitochondrial apoptotic pathway, was observed. In contrast, RSV infection strongly activated caspase-12, an endoplasmic reticulum (ER) stress response caspase. Activation of the ER stress response was further evidenced by upregulation of ER chaperones BiP and calnexin. Antisense-mediated inhibition of caspase-12 inhibited apoptosis. Inhibitors of NF-kappa B had no effect on apoptosis. Thus, RSV-induced apoptosis appears to occur through an ER stress response that activates caspase-12, and is uncoupled from NF-kappa B activation.
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PMID:An endoplasmic reticulum-specific stress-activated caspase (caspase-12) is implicated in the apoptosis of A549 epithelial cells by respiratory syncytial virus. 1113 74

Apoptosis induced by etoposide (VP-16) in HL-60 cells was confirmed to be caspase-dependent. It was fully inhibited by the broad-spectrum caspase inhibitor Z-VAD-fmk. However, the caspase-3-specific inhibitor Z-DEVDfmk only partially inhibited apoptosis. This indicated that a second caspase is required in vivo for full activation of the apoptotic nucease CAD. Aurin tricarboxylic acid (ATA) did not inhibit VP-16-induced apoptosis. In contrast, apoptosis induced by hydroxychloroquine (HCQ) in HL-60 cells was caspase-3 independent and was fully inhibited by ATA. Thus, CAD does not appear to be involved in chromatin DNA degradation in this case. A second apoptotic nuclease is postulated to degrade the DNA, likely endo- exonuclease, an abundant nuclear enzyme that acts on both DNA and RNA and is present in latent form. HCQ, but not VP-16, stimulated DNA degradation ("laddering") in isolated nuclei. This indicates that the drug can act directly in the nuclei to trigger activation of the second latent apoptotic nuclease.
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PMID:Caspase-3-dependent and caspase-3-independent pathways leading to chromatin DNA fragmentation in HL-60 cells. 1122 93

DFF ((DNA Fragmentation Factor) is a heterodimer composed of 40 kDa (DFF40, CAD) and 45 kDa (DFF45, ICAD) subunits. During apoptosis, activated caspase-3 cleaves DFF45 and activates DFF40, a DNase that targets nucleosomal linker region and cleaves chromatin DNA into nucleosomal fragments. We have previously reported that HT induced apoptosis in HL-60 cells, and intracellular Ca(2+) chelator BAPTA blocked apoptosis-associated DNA fragmentation induced by HT. We report here that HT also induced activation of caspase-3 and cleavage of DFF45. BAPTA prevented neither the caspase-3 activation nor the cleavage of DFF45. Mitochondrial membrane potential was disrupted in BAPTA-AM treated cells. However, BAPTA did prevent DNA fragmentation and chromatin condensation in HT-treated cells. These data suggest a novel role for intracellular calcium in regulating apoptotic nuclease that causes DNA fragmentation and chromatin condensation.
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PMID:BAPTA blocks DNA fragmentation and chromatin condensation downstream of caspase-3 and DFF activation in HT-induced apoptosis in HL-60 cells. 1144 71


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