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)

Regardless of the existence of ceramide-related molecules, such as sphingomyelin (SM), neutral sphingomyelinase (nSMase), and SM synthase, in the nucleus, the regulation of ceramide in the nucleus is poorly understood in stress-induced apoptosis. In Fas-induced Jurkat T-cell apoptosis, we found a time- and dose-dependent increase of ceramide content in the nuclear and microsomal fractions. Fas-induced increase of ceramide content in the nucleus also was detected by confocal microscopy using anticeramide antibody. Activation of nSMase and inhibition of SM synthase were evident in the nuclear fraction after Fas cross-linking, whereas nSMase was activated, but SM synthase was not affected, in the microsomal fraction. Pretreatment with D-609, a putative SM synthase inhibitor, enhanced Fas-induced increase of ceramide in the nucleus and induction of apoptosis along with increase of Fas-induced inhibition of nuclear SM synthase. Fas-induced activation of caspase-3 was detected in the nuclear fraction and in whole cell lysate. A caspase-3 inhibitor, acetyl-Asp-Glu-Val-Asp-chloromethyl ketone, blocked not only Fas-induced increases of apoptosis and ceramide content but also Fas-induced activation of nSMase and inhibition of SM synthase in the nuclear fraction. Taken together, it is suggested that the nucleus is a site for ceramide increase and caspase-3 activation in Fas-induced Jurkat T-cell apoptosis and that caspase-3-dependent regulation of the "SM cycle" consisting of nSMase and SM synthase plays a role in Fas-induced ceramide increase in the nucleus.
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PMID:Increase of nuclear ceramide through caspase-3-dependent regulation of the "sphingomyelin cycle" in Fas-induced apoptosis. 1487 31

We have shown that overexpression of SMS1, an enzyme that converts de novo ceramide into sphingomyelin, is accompanied by attenuated ceramide response and apoptotic resistance after photodamage with the photosensitizer Pc 4 (photodynamic therapy; PDT). To test whether SMS1 overexpression-related effects after PDT can be reversed, in this study SMS1 was downregulated in Jurkat T lymphoma/leukemia cells using small inhibitory RNA (siRNA) for SMS1. Compared to scrambled (control) siRNA-transfectants, in SMS1 siRNA-transfected cells the activity of SMS at rest was downregulated with concomitant decrease in sphingomyelin mass. In SMS1 siRNA-transfected cells increases in ceramides were higher than in control siRNA-transfectants after PDT. Similar findings were obtained for dihydroceramides suggesting the involvement of de novo ceramide pathway. PDT-induced DEVDase (caspase-3-like) activation was enhanced in SMS1 siRNA-transfected cells compared to their control counterparts. The data show that RNA interference-dependent downregulation of SMS1 is associated with increased accumulation of ceramide and dihydroceramide with concomitant sensitization of cells to apoptosis after photodamage. Similarly, in SMS2 siRNA-transfected cells, downregulation of SMS activity was accompanied by potentiated DEVDase activation post-photodamage. These findings suggest that SMS is a potential novel molecular target that can augment therapeutic efficacy of PDT.
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PMID:Suppression of sphingomyelin synthase 1 by small interference RNA is associated with enhanced ceramide production and apoptosis after photodamage. 1837 17

The present study tested the hypothesis that short-term dietary deficiency of magnesium (Mg) (21 days) in rats would 1) result in decreased serum(s) [the present study tested the levels of Mg, sphingomyelin (SM), and phosphatidylcholine (PC)]; 2) promote DNA fragmentation, lipid peroxidation (LP), and activation of caspase-3 in cardiac (ventricular and atrial) and vascular(aortic) muscle; and 3) low levels of Mg(2+) added to drinking water would either prevent or greatly ameliorate these manifestations. The data indicate that short-term Mg deficiency (10% normal dietary intake) resulted in profound reductions in serum-ionized Mg and total Mg with an elevation in serum-ionized calcium (Ca(2+)), significant lowering of serum SM and serum PC, with concomitant LP, DNA fragmentation, and activation of caspase-3 in ventricular (right and left chambers), atrial (right and left chambers) and abdominal aortic smooth muscle. The greater the reduction in serum-ionized Mg, the greater the effects on DNA fragmentation, LP, and caspase-3 activity. The intake of water-borne Mg(2+) at all levels greatly attenuated or inhibited the reductions in serum SM and serum PC, activation of LP, DNA fragmentation, and the activation of caspase-3; even very low levels of Mg(2+) in drinking water (i.e., 15 parts.million(-1).day(-1)) were cardio- and vascular protective. In addition, we demonstrate that short-term dietary deficiency of Mg probably results in a downregulation of SM synthase and a decreased synthesis of PC.
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PMID:Short-term magnesium deficiency results in decreased levels of serum sphingomyelin, lipid peroxidation, and apoptosis in cardiovascular tissues. 1942 13

Ceramide can be converted into sphingomyelin by sphingomyelin synthases (SMS) 1 and 2. In this study, we show that in human leukemia Jurkat cells, which express mainly SMS1, Fas ligand (FasL) treatment inhibited SMS activity in a dose- and time-dependent manner before nuclear fragmentation. The SMS inhibition elicited by FasL (1) was abrogated by benzyloxycarbonyl valyl-alanyl-aspartyl-(O-methyl)-fluoromethylketone (zVAD-fmk), a broad-spectrum caspase inhibitor; (2) did not occur in caspase-8-deficient cells and (3) was not affected in caspase-9-deficient cells. Western blot experiments showed SMS1 cleavage in a caspase-dependent manner upon FasL treatment. In a cell-free system, caspase-2, -7, -8 and -9, but not caspase-3 and -10, cleaved SMS1. In HeLa cells, SMS1 was Golgi localized and relocated throughout the cytoplasm in cells exhibiting an early apoptotic phenotype on FasL treatment. zVAD-fmk prevented FasL-induced SMS1 relocation. Thus, FasL-mediated SMS1 inhibition and relocation depend on caspase activation and likely represent proximal events in Fas signaling. FasL-induced ceramide production and cell death were enhanced in cells stably expressing an siRNA against SMS1. Conversely, in cells stably overexpressing SMS1, FasL neither increased ceramide generation nor efficiently induced cell death. Altogether, our data show that SMS1 is a novel caspase target that is functionally involved in the regulation of FasL-induced apoptosis.
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PMID:Caspase-mediated inhibition of sphingomyelin synthesis is involved in FasL-triggered cell death. 1977 94

Inhibitors of topoisomerase I, such as camptothecin, have proven to be among the most promising new classes of anti-neoplastic agents introduced into the clinical setting in recent years. Irinotecan (CPT-11) is one of the most widely used camptothecin analogs and is converted to form the active metabolite SN-38. The present study was designed to explore apoptosis induced by SN38 and anti-Fas antibody (CH11) in WR/Fas-SMS1 cells and its possible mechanisms. The results demonstrate that combination of SN38 and CH11 synergistically enhanced cell apoptosis in WR/Fas-SMS1 cells. Western blotting analysis showed that combination of SN38 and CH11 activated the ATM-Chk1-p53 pathway, increased protein expression of phospho-p53 and cleavaged caspase-3, but down-regulated expression of phospho-p21. Our data suggest that combination of SN38 and CH11 enhanced apoptosis through down-regulation of p21 phosphorylation. In conclusion, inhibition of p21 could be a new adjuvant approach in cancer therapy.
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PMID:Synergistic effects of topoisomerase I inhibitor, SN38, on Fas-mediated apoptosis. 2103 2

Curcumin exhibits anti-cancer properties manifested by activation of pro-apoptotic signaling. We have demonstrated earlier that apoptosis of HL-60 human leukemia cells induced by curcumin is controlled by ceramide generated by neutral sphingomyelinase (nSMase) which contributes to sphingomyelin synthase (SMS) inhibition favoring accumulation of ceramide in cells. Here we report that the activity of nSMase, ceramide accumulation and death of HL-60 cells are inhibited by overexpression of Bcl-xL or Bcl-2 proteins, while down-regulation of nSMase interferes with degradation of Bcl-2 but not Bcl-xL. Activation of nSMase in curcumin-treated cells requires the activity of apoptosis initiator caspase-8 and executioner caspase-3, whereas nSMase depletion prevents activation of caspase-3, but not caspase-8. These data place nSMase activation downstream of caspase-8 and Bcl-xL and indicate a mutual regulation between nSMase and caspase-3 activity on one hand, and Bcl-2 level on the other hand in curcumin-treated cells. The activation of nSMase and ceramide accumulation also depended on the depletion of glutathione. The depletion of glutathione required the activity of caspase-8 and caspase-3 as well as the down-regulation of Bcl-2 and Bcl-xL. Together, the data indicate a crosstalk among Bcl-2, Bc-xL, caspases and glutathione during curcumin-induced apoptosis and point to the superior role of caspase-8 activity, Bcl-xL down-regulation and glutathione depletion in the pro-apoptotic cascade leading to nSMase activation and generation of ceramide.
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PMID:Ceramide generation during curcumin-induced apoptosis is controlled by crosstalk among Bcl-2, Bcl-xL, caspases and glutathione. 2623 16