Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.21.1 (DNase)
 7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the mechanism whereby nuclear DNA fragmentation activity emerging during early apoptosis is inhibited during normal cell life. In a cell-free system, cytosol fractions from diverse nonapoptotic human cell lines (Jurkat T-cell leukemia, HeLa carcinoma, SK-N-MC neuroblastoma, and WI-38 embryonic lung fibroblast) potently neutralized the nuclear DNA fragmentation activity of cytosol from apoptotic anti-Fas treated Jurkat cells. Recombinant human DNA fragmentation factor 45 kDa subunit (DFF45/ICAD), an inhibitor of the caspase-activated DNase DFF40/CAD, substituted for healthy cytosol in inhibiting DNA fragmentation. An antiserum against human DFF45 detected 44 and 34 kDa proteins (major and minor, respectively) in the cytosols but not in the nuclear or membrane fractions of various cultured human cells. Cytosols depleted of DFF45/ICAD by immunoadsorption had little or no inhibitor of nuclear DNA fragmentation activity and no caspase-activated DNA fragmentation activity. We conclude that immunoreactive DFF45/ICAD is the principal inhibitor of apoptotic DNase activity in the cytosol of healthy cells.
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PMID:Inhibition of apoptosis-associated DNA fragmentation activity in nonapoptotic cells: the role of DNA fragmentation factor-45 (DFF45/ICAD). 987 36

We asked whether the antiangiogenic action of 16K human PRL (hPRL), in addition to blocking mitogen-induced vascular endothelial cell proliferation, involved activation of programmed cell death. Treatment with recombinant 16K hPRL increased DNA fragmentation in cultured bovine brain capillary endothelial (BBE) and human umbilical vein endothelial (HUVE) cells in a time- and dose-dependent fashion, independent of the serum concentration. The activation of apoptosis by 16K hPRL was specific for endothelial cells, and the activity of the peptide could be inhibited by heat denaturation, trypsin digestion, and immunoneutralization, but not by treatment with the endotoxin blocker, polymyxin-B. 16K hPRL-induced apoptosis was correlated with the rapid activation of caspases 1 and 3 and was blocked by pharmacological inhibition of caspase activity. Caspase activation was followed by inactivation of two caspase substrates, poly(ADP-ribose) polymerase (PARP) and the inhibitor of caspase-activated deoxyribonuclease (DNase) (ICAD). Furthermore, 16K hPRL increased the conversion of Bcl-X to its proapoptotic form, suggesting that the Bcl-2 protein family may also be involved in 16K hPRL-induced apoptosis. These findings support the hypothesis that the antiangiogenic action of 16K hPRL includes the activation of programmed cell death of vascular endothelial cells.
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PMID:The antiangiogenic factor 16K PRL induces programmed cell death in endothelial cells by caspase activation. 1104 70

ICAD / DFF is a downstream molecule of caspases, participating in nuclear DNA fragmentation during apoptosis. ICAD / DFF binds CAD / DFF40 and inhibits its DNase activity. ICAD / DFF has two alternative isoforms, long isoform (ICAD-L / DFF45) and short isoform (ICAD-S / DFF35). We have studied the presence and functional status of ICAD / DFF in human glioma cell lines. All cell lines tested expressed both ICAD-L and ICAD-S. When the cultured glioma cells were exposed to anti-Fas antibody, these isoforms were degraded prior to the fragmentation of the nuclear DNA, indicating that the ICAD / DFF expressed in cultured glioma cells was potentially functional. In primary brain tumors and normal brain tissues, there was a difference in the expression level between ICAD-L and ICAD-S. In glioblastomas, ICAD-S was more abundant than ICAD-L. In contrast, ICAD-L was more abundant than ICAD-S in medulloblastomas. The present findings suggest that primary brain tumors and normal brain constitutively express ICAD / DFF, and that there is a difference between the expression levels of ICAD-L and ICAD-S.
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PMID:Expression of ICAD-l and ICAD-S in human brain tumor and its cleavage upon activation of apoptosis by anti-Fas antibody. 1147 33

Deoxyribonucleic acid fragmentation at nucleosomal junctions is a hallmark of neuronal apoptosis in ischemic brain injury, for which the mechanism is not fully understood. Using the in vitro cell-free apoptosis assay, the authors found that caspase-3-dependent deoxyribonuclease activity caused internucleosomal DNA fragmentation in brain-cell extracts in a rat model of transient focal ischemia. This in vitro deoxyribonuclease activity was completely inhibited by purified inhibitor of caspase-activated deoxyribonuclease protein, the specific endogenous inhibitor of caspase-activated deoxyribonuclease, or by caspase-activated deoxyribonuclease immunodepletion. The induction of the deoxyribonuclease activity was correlated with caspase-3 activation and caspase-3-mediated degradation of inhibitor of caspase-activated deoxyribonuclease. Furthermore, inhibiting caspase-3-like protease activity prevented the endogenous induction of internucleosomal DNA fragmentation in the ischemic brain. These results suggest that caspase-3-dependent caspase-activated deoxyribonuclease activity plays an important role in mediating DNA fragmentation after focal ischemia.
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PMID:Induction of caspase-activated deoxyribonuclease activity after focal cerebral ischemia and reperfusion. 1180 89

The inhibitor of caspase-3-activated DNase (ICAD) is a caspase-3 substrate that controls nuclear apoptosis. ICAD has two isoforms: a functional isoform of M(r) 45,000, ICAD-L/DNA fragmentation factor (DFF) 45; and a M(r) 35,000 isoform, ICAD-S/DFF35. ICAD-deficient murine cells display resistance to apoptotic stimuli and absence of typical nuclear changes of apoptosis. Our aim was to: (a) characterize the ICAD expression in several human colonic cancer cell lines compared with human normal colonocytes; and (b) correlate the phenotypic features of apoptosis to the level of ICAD expression. ICAD expression was assessed by immunoblot analysis. Early markers of apoptosis of cultured cells included lactate dehydrogenase retention in dying cells, cytokeratin 18 cleavage, and caspase-3 activation. Nuclear markers of apoptosis were assessed by Hoechst staining of nuclei, electron microscopy, and DNA electrophoresis. Inhibition of caspases was performed using a broad-spectrum caspase inhibitor, z-Val-Ala-Asp-fluoromethyl ketone. ICAD expression was restricted to the functional ICAD-L/DFF45 isoform in colonic cancer cells as well as in human normal colonocytes. In a clonal derivative of HT29 cells (HT29-Cl.16E cells), ICAD expression was found to be down-regulated during the exponential phase of growth, and the cell death triggered by IFN-gamma, anti-Fas antibody plus Adriamycin was characterized by the expression of early markers of apoptosis, whereas the key nuclear features of apoptosis were absent. In contrast, exposure of confluent cells to this treatment led to a typical apoptotic nuclear fragmentation. Both forms of apoptosis, in exponentially growing and confluent cells, were sensitive to the broad spectrum inhibitor of caspases, z-Val-Ala-Asp-fluoromethyl ketone. Our findings support the concept that the expression of ICAD is essential to the execution of full-blown apoptosis in colonic cancer cells. Altogether, our results point to ICAD as a potential target for restoring a normal apoptotic signal transduction pathway in colonic cancer cells.
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PMID:Growth phase-dependent expression of ICAD-L/DFF45 modulates the pattern of apoptosis in human colonic cancer cells. 1192 40

DFF45/ICAD has dual functions in the final stage of apoptosis, by acting as both a folding chaperone and a DNase inhibitor of DFF40/CAD. Here, we present the solution structure of the C-terminal domain of DFF45, which is essential for its chaperone-like activity. The structure of this domain (DFF-C) consists of four alpha helices, which are folded in a novel helix-packing arrangement. The 3D structure reveals a large cluster of negatively charged residues on the molecular surface of DFF-C. This observation suggests that charge complementation plays an important role in the interaction of DFF-C with the positively charged catalytic domain of DFF40, and thus for the chaperone activity of DFF45. The structure of DFF-C also provides a rationale for the loss of the chaperone activity in DFF35, a short isoform of DFF45. Indeed, in DFF35, the amino acid sequence is truncated in the middle of the second alpha helix constituting the structure of DFF-C, and thus both the hydrophobic core and the cluster of negative charges are disrupted.
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PMID:Solution structure of the DFF-C domain of DFF45/ICAD. A structural basis for the regulation of apoptotic DNA fragmentation. 1214 88

It has been proposed that the hemodynamic deterioration associated with heart failure (HF) may be due in part to ongoing loss of viable cardiac myocytes through apoptosis. Hypoxia has been shown to promote apoptosis in normal cardiomyocytes. Adaptation and maladaptations inherent to heart failure can modify the susceptibility of cells to different stress factors. We hypothesized that HF modifies the threshold of cardiomyocytes to hypoxia-induced apoptosis. Cardiomyocytes were isolated from 18 human hearts explanted at the time of cardiac transplantation due to either ischemic cardiomyopathy (ICM) (n = 9) or idiopathic dilated cardiomyopathy (IDC) (n = 9). Tissue from five normal donor hearts (NL) for whom no suitable recipient was available was used as control. Cardiomyocytes were incubated for 3 h under normoxic (95% air-5% CO(2)) or hypoxic (95% N(2)-5% CO(2)) conditions. Expression of caspase-3 and DNA fragmentation factor-45 (DFF45)/inhibitor of caspase-3-activated DNase (ICAD) was detected by Western blot analysis. Three hours of hypoxia did not affect the expression of these proteins in NL cardiomyocytes. In contrast, hypoxia led to cleavage of caspase-3 and DFF45/ICAD both in ICM and IDC. In conclusion, failing cardiomyocytes exhibit increased susceptibility to hypoxia-induced apoptosis.
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PMID:Hypoxia-induced cleavage of caspase-3 and DFF45/ICAD in human failed cardiomyocytes. 1218 Nov 28