Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The full mechanisms underlying neuronal death following excitotoxic insult remain unclear, despite many in vivo and in vitro studies. Recent work has focused on various signaling molecules and pathways, normally strictly regulated, that can trigger death if perturbed. The transcription factor, E2F1 is pivotal in controlling cell death under stress situations. The current study aimed to investigate the role of this transcription factor in modulating neuronal death following kainic acid (KA) treatment of cultured mouse cerebellar granule cells (CGCs). KA-induced death of CGCs was attenuated by the selective KA/AMPA receptor antagonist CNQX, but not MK-801. Such neuronal death was caspase-3-independent and did not activate many known death genes, such as Fas receptor, caspase-8 and p38. However, hyperphosphorylation of Rb showed a transient increase which may lead to activation of E2F1. Indeed E2F1 +/+ and -/- CGCs showed a differential response to KA-mediated toxicity, in that E2F1 -/- neurons were significantly less susceptible to KA compared to E2F1 +/+ neurons, albeit both E2F1 +/+ and -/- neurons expressed similar levels of KA receptors and responded similarly to kainate antagonist, CNQX. Using selective inhibitors to CDKs, such as olomoucine, roscovitine and flavopiridol, and the inhibitor SB203580 to p38 MAPK, we ruled out the possibility that Rb inactivation through hyperphosphorylation was due to either upstream kinases. Therefore activation of Rb/E2F1 pathway appears to involve novel interactions yet to be elucidated.
Brain Res Mol Brain Res 2003 Aug 19
PMID:Involvement of the transcription factor E2F1/Rb in kainic acid-induced death of murine cerebellar granule cells. 1294 62

SH-SY5Y neuroblastoma cells were cultured for up to three serial passages in the presence of the copper chelator triethylene tetramine (Trien). The copper-depleted neuroblastoma cell line obtained showed decreased activities of the copper enzymes Cu, Zn super-oxide dismutase and cytochrome c oxidase with concomitant increases in reactive oxygen species. Mitochondrial antioxidants (Mn superoxide dismutase and Bcl-2)were up-regulated. Overexpression and activation of p53 were early responses, leading to an increase in p21. Eventually, copper-depleted cells detached from the monolayer and underwent apoptosis. Activation of upstream caspase-9, but not caspase-8, suggested that apoptosis proceeds via a mitochondrial pathway, followed by caspase-3 activation. The addition of copper sulfate to the copper-depleted cells restored copper enzymes, normalized antioxidant levels and improved cell viability. We conclude that prolonged copper starvation in these replicating cells leads to mitochondrial damage and oxidative stress and ultimately, apoptosis.
Cell Mol Life Sci 2003 Aug
PMID:Prolonged copper depletion induces expression of antioxidants and triggers apoptosis in SH-SY5Y neuroblastoma cells. 1451 38

The serine protease granzyme B (GrB; 25 kDa) is capable of inducing apoptosis through both caspase-dependent and caspase-independent mechanisms. We designed a novel vascular-targeting fusion construct designated as GrB/vascular endothelial growth factor (VEGF)121, which is composed of a non-heparin-binding isoform of VEGF and the proapoptotic pathway enzyme GrB fused via a short, flexible tether (G4S). The chimeric fusion gene was then cloned into a bacterial vector, and the protein was expressed in Escherichia coli and purified by nickel-NTA metal affinity chromatography. Western blotting confirmed incorporation of both VEGF121 and GrB proteins into the construct. GrB/VEGF121 specifically bound (ELISA) to porcine aortic endothelial (PAE)/FLK-1 cells overexpressing the FLK-1/KDR receptor but not to cells overexpressing the FLT-1 receptor. Immunofluoresence studies showed that the GrB moiety of GrB/VEGF121 was delivered efficiently and rapidly into the cytosol of PAE/FLK-1 cells but not into that of PAE/FLT-1 cells after 4 h treatment with GrB/VEGF121. Treatment of cells with GrB/VEGF121 showed that the IC50 was approximately 10 nM against PAE/FLK-1 cells; however, there were no cytotoxic effects observed on PAE/FLT-1 cells at doses up to 200 nM. GrB/VEGF121 induced apoptotic events specifically on PAE/FLK-1 as assessed by terminal deoxynucleotidyl transferase-mediated nick end labeling assay, DNA laddering, and cytochrome c release from mitochondria. In addition, the fusion construct mediated the cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase in target endothelial cells within 4 h after treatment. In conclusion, delivery of the human proapoptotic pathway enzyme GrB to tumor vascular endothelial cells or to tumor cells may have significant therapeutic potential and represents a potent new class of targeted therapeutic agents with a unique mechanism of action.
Mol Cancer Ther 2003 Oct
PMID:Mechanistic studies of a novel human fusion toxin composed of vascular endothelial growth factor (VEGF)121 and the serine protease granzyme B: directed apoptotic events in vascular endothelial cells. 1457 60

To date, two major apoptotic pathways, the death receptor and the mitochondrial pathway, have been well documented in mammalian cells. However, the involvement of these two apoptotic pathways, particularly the death receptor pathway, in transforming growth factor-beta 1 (TGF-beta 1)-induced apoptosis is not well understood. Herein, we report that apoptosis of human gastric SNU-620 carcinoma cells induced by TGF-beta 1 is caused by the Fas death pathway in a Fas ligand-independent manner, and that the Fas death pathway activated by TGF-beta 1 is linked to the mitochondrial apoptotic pathway via Bid mediation. We showed that TGF-beta 1 induced the expression and activation of Fas and the subsequent caspase-8-mediated Bid cleavage. Interestingly, expression of dominant negative FADD and treatment with caspase-8 inhibitor efficiently prevented TGF-beta 1-induced apoptosis, whereas the treatment with an activating CH11 or a neutralizing ZB4 anti-Fas antibody, recombinant Fas ligand, or Fas-Fc chimera did not affect activation of Fas and the subsequent induction of apoptosis by TGF-beta 1. We further demonstrated that TGF-beta 1 also activates the mitochondrial pathway showing Bid-mediated loss of mitochondrial membrane potential and subsequent cytochrome c release associated with the activations of caspase-9 and the effector caspases. Moreover, all these apoptotic events induced by TGF-beta 1 were found to be effectively inhibited by Smad3 knockdown and also completely abrogated by Smad7 expression, suggesting the involvement of the Smad3 pathway upstream of the Fas death pathway by TGF-beta 1.
Mol Biol Cell 2004 Feb
PMID:Transforming growth factor-beta 1 induces apoptosis through Fas ligand-independent activation of the Fas death pathway in human gastric SNU-620 carcinoma cells. 1459 20

PPARgamma is known to induce apoptosis in malignant tumor cells, but the mechanism of this induction is not well understood. We investigated induction of apoptosis with 15-Deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), a PPARgamma ligand, in cholangio cell carcinoma (CCC) cells (RBE, ETK-1 or HuCCT-1). Apoptosis was induced in RBE and ETK-1 cells with 15d-PGJ2, but not in HuCCT-1 cells, although PPARgamma was expressed in all CCC cells. Apoptosis-related proteins were also expressed, including FLIP, bclx, Apaf-1 and XIAP, but expression levels differed among the three cell lines. RBE cells treated with 15d-PGJ2 showed caspase activation, and it appeared that PPARgamma-induced apoptosis was dependent on caspase activation. However, neither ETK-1 nor HuCCT-1 cells showed significant activation of caspase-8 or -3 with 15d-PGJ2 treatment, raising the possibility of a caspase-independent apoptosis induction pathway. XIAP was down-regulated by 15d-PGJ2 in all three CCC cell lines. Therefore, 15d-PGJ2 induces apoptosis in CCC cells via caspase-dependent or independent pathways. 15d-PGJ2 may also induce down-regulation of XIAP and may promote caspase cascade activation through TNF-family receptor signaling pathways.
Int J Mol Med 2003 Dec
PMID:The PPARgamma ligand, 15-Deoxy-Delta12,14-PGJ2, regulates apoptosis-related protein expression in cholangio cell carcinoma cells. 1461 59

Prostate cancer is a major health threat for American men. Therefore, the development of effective therapeutic options is an urgent issue for prostate cancer treatment. In this study, we evaluated the effect of glycogen synthase kinase-3beta (GSK-3beta) suppression on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human prostate cancer cell lines. In the presence of lithium chloride (LiCl) or SB216763, the GSK-3beta inhibitors, TRAIL-induced cell death was dramatically enhanced, and the enhanced cell death was an augmented apoptotic response evidenced by increased Annexin V labeling and caspase-3 activation. GSK-3beta gene silencing mediated by a small interference RNA (siRNA) duplex also sensitized the cells to TRAIL, confirming the specificity of GSK-3beta suppression. Importantly, TRAIL stimulation increased GSK-3beta tyrosine phosphorylation at Y216, suggesting that GSK-3beta is activated by TRAIL. Furthermore, TRAIL sensitization was associated with increased proteolytic procession of caspase-8 and its downstream target BID, and z-IETD-FMK, the inhibitor specific to active caspase-8 totally blocked LiCl-induced TRAIL sensitization. Finally, Trichodion, a potent nuclear factor-kappaB (NF-kappaB) inhibitor, could not affect LiCl-induced TRAIL sensitization, although GSK-3beta inhibitors significantly blocked TRAIL-reduced NF-kappaB activity in prostate cancer cells. These results indicate that GSK-3beta suppression sensitizes prostate cancer cells to TRAIL-induced apoptosis that is dependent on caspase-8 activities but independent of NF-kappaB activation, and suggest that a mechanism involving GSK-3beta activation may be responsible for TRAIL resistance in prostate cancer cells.
Mol Cancer Ther 2003 Nov
PMID:Glycogen synthase kinase-3beta suppression eliminates tumor necrosis factor-related apoptosis-inducing ligand resistance in prostate cancer. 1461 95

Signalling through the death receptor CD95 induces apoptosis by formation of a signalling complex at the cell membrane and subsequent caspase-8 and caspase-3-activation. Treatment of Jurkat T cells with protonophores across the mitochondrial membrane such as 2,4-dinitrophenol (DNP) enhances the death-inducing capacity of CD95. In this study, we show that this enhancement is due to the specific acceleration of caspase-8-processing and activation at the CD95-receptor. DNP-treatment did not affect NF-kappaB-induction by CD95. Immunoprecipitation experiments showed that the amounts of the adapter FADD/MORT1 and pro-caspase-8 at the CD95-receptor were not altered by DNP. Subcellular fractionation studies revealed that the amount of mature caspase-8 but not pro-caspase at the membrane was increased following CD95-stimulation in the presence of DNP. As a consequence of caspase-activation, c-FLIP-levels in the cytosol decreased. In Jurkat cells overexpressing c-FLIPS, DNP was still able to enhance caspase-activation. The enhancing capacity of DNP was seen in some cell lines (Jurkat, CEM and HeLa) but not in SKW6 cells and was also found in mitogen-stimulated human T cells. Furthermore, the enhancement extended to TRAIL-induced caspase-activation. Thus, a mechanism exists by which caspase-8-activation can be accelerated at death receptors and this mechanism can be triggered by targeting mitochondrial oxidative phosphorylation.
Mol Immunol 2004 Jan
PMID:Enhancement of death-receptor induced caspase-8-activation in the death-inducing signalling complex by uncoupling of oxidative phosphorylation. 1464 92

Duchenne muscular dystrophy is an X-linked recessive disorder, primarily characterized by progressive muscle weakness and wasting. The disease results from the absence of dystrophin, however the precise molecular mechanisms leading to muscle pathology are poorly understood. Dystrophic muscles undergo increased oxidative stress and altered calcium homeostasis, which may contribute to myofiber loss by triggering both necrosis and apoptosis. Recent studies have identified ARC (apoptosis repressor with caspase recruitment domain) as an abundant protein in human muscle that can inhibit both hypoxia and caspase-8-induced apoptosis as well as protect cells from oxidative stress. To explore a potential role for ARC in protecting muscle fibers from dystrophic breakdown, we have cloned and characterized murine ARC and studied its expression in normal and dystrophic mouse muscle. ARC is expressed at high levels in striated muscle and displays fiber-type restricted expression patterns. ARC expression levels are normal in dystrophic mdx mice, although the intracellular localization pattern of ARC is slightly altered compared with normal muscles. Overexpression of ARC in transgenic mdx mice failed to alleviate the dystrophic pathology in skeletal muscles, suggesting that misregulation of the molecular pathways regulated by ARC does not significantly contribute to myofiber death.
Hum Mol Genet 2004 Jan 15
PMID:Characterization of ARC, apoptosis repressor interacting with CARD, in normal and dystrophin-deficient skeletal muscle. 1464 4

Previous studies have demonstrated that cotreatment with mitogen activated-protein kinase kinase (MEK) 1/2 inhibitors (e.g., PD184352) and the checkpoint abrogator 7-hydroxystaurosporine (UCN-01) dramatically induces apoptosis in a variety of human leukemia and multiple myeloma cell types. The purpose of this study was to evaluate the roles of Bcl-2 family members and the relative contribution of the intrinsic mitochondrial versus the extrinsic receptor-related apoptotic pathways to MEK inhibitors/UCN-01-induced leukemic cell death. Cotreatment of U937 cells with PD184352 and UCN-01 resulted in the activation of procaspase-3, -9, and -8 as well as Bid cleavage. PD184352/UCN-01-induced mitochondrial dysfunction and apoptosis were both substantially attenuated in cells ectopically expressing Bcl-2, an N-terminal phosphorylation loop-deleted mutant Bcl-2, or Bcl-xL, but not in cells expressing dominant-negative (DN) caspase-8, cytokine response modifier A (cowpox virus-encoded antiapoptotic protein), or DN Fas-associated death domain. Coadministration of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) or TNF-alpha substantially increased MEK inhibitors (e.g., PD184352 or U0126)/UCN-01-induced mitochondrial dysfunction, activation of procaspase-8 and Bid, and apoptosis in Bcl-2- and Bcl-xL-overexpressing cells but not in those in which the extrinsic pathway was interrupted. Together, these findings suggest that the MEK inhibitors/UCN-01 regimen primarily induces leukemic cell apoptosis by engaging the intrinsic, mitochondrial apoptotic pathway and that resistance to these events conferred by increased expression of certain antiapoptotic Bcl-2 family members can be overcome, at least in part, by coadministration of TRAIL and other agents that activate the extrinsic apoptotic cascade.
Mol Pharmacol 2003 Dec
PMID:Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) promotes mitochondrial dysfunction and apoptosis induced by 7-hydroxystaurosporine and mitogen-activated protein kinase kinase inhibitors in human leukemia cells that ectopically express Bcl-2 and Bcl-xL. 1464 70

The mechanism of action of fenretinide, a synthetic retinoid currently undergoing testing as a chemopreventive and chemotherapeutic agent, is incompletely understood. In the present study, fenretinide caused apoptotic changes, including DNA fragmentation and cleavage of caspase substrates, in six low-passage ovarian cancer cell lines. However, the caspase activation pathway used by this agent varied. Transient transfection of cDNA-encoding cytokine response modifier A (CrmA), a caspase-8 inhibitor, diminished fenretinide-induced death in OV177 cells. Likewise, IETD(OMe)-fluoromethylketone (fmk) inhibited fenretinide-induced apoptosis by >80% in OV177 or OV266 cells and by approximately 50% in OV17, OV167, or OV207 cells. Further analysis demonstrated that inhibition of Fas ligand, tumor necrosis factor-alpha, or TRAIL signaling with blocking reagents did not affect fenretinide-induced apoptosis, raising the possibility that fenretinide activates caspase-8 in a death receptor-independent manner. In contrast, CrmA transfection or IETD(OMe)-fmk treatment did not inhibit fenretinide-induced apoptosis in OV202 cells. These divergent behaviors did not correlate with increased levels of procaspase-10, which is relatively resistant to CrmA and IETD(OMe)-fmk, nor with the expression of procaspase-8 and -9, apoptotic protease activating factor-1, or cellular FLICE-like inhibitory protein. Similarly, fenretinide treatment increased ceramide levels equally in cells that do (OV177) and do not (OV202) rely on caspase-8 to initiate apoptosis. These results indicate that synthetic retinoids can use caspase-8 as an initiating caspase, but they also indicate unexpected heterogeneity in caspase activation pathways among closely related cell lines.
Mol Pharmacol 2003 Dec
PMID:Heterogeneous role of caspase-8 in fenretinide-induced apoptosis in epithelial ovarian carcinoma cell lines. 1464 74


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