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See detailMechanism of Colon Cancer Cell Apoptosis Mediated by Pyropheophorbide-a Methylester Photosensitization
Matroule, Jean-Yves; Carthy, Chris M; Granville, David J et al

in Oncogene (2001), 20

Pyropheophorbide-a methylester (PPME) is a second generation of photosensitizers used in photodynamic therapy (PDT). We demonstrated that PPME photosensitization triggered apoptosis of colon cancer cells ... [more ▼]

Pyropheophorbide-a methylester (PPME) is a second generation of photosensitizers used in photodynamic therapy (PDT). We demonstrated that PPME photosensitization triggered apoptosis of colon cancer cells as measured by using several classical parameters such as DNA laddering, PARP cleavage, caspase activation and mitochondrial release of cytochrome c. Preincubation of cells with N-acetyl cysteine (NAC) or pyrolidine dithiocarbamate (PDTC) protected against apoptosis mediated by PPME photosensitization showing that reactive oxygen species (ROS) are involved as second messengers. On the other hand, photosensitization carried out in the presence of deuterium oxide (D2O) which enhances singlet oxygen (1O2) lifetime only increases necrosis without affecting apoptosis. Since PPME was localized in the endoplasmic reticulum (ER)/Golgi system and lysosomes, other messengers than ROS were tested such as calcium, Bid, Bap31, phosphorylated Bcl-2 and caspase-12 but none was clearly identified as being involved in triggering cytochrome c release from mitochondria. On the other hand, we demonstrated that the transduction pathways leading to NF-kappaB activation and apoptosis were clearly independent although NF-kappaB was shown to counteract apoptosis mediated by PPME photosensitization. [less ▲]

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See detailImage du mois. Abces cerebral et toxoplasmose.
Omazic, A. F.; Welter, P.; Piette, Jacques ULg et al

in Revue Médicale de Liège (2001), 56(8), 541-2

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See detailImportance of post-transcriptional regulation of chemokine genes by oxidative stress.
JOSSE, Claire ULg; Boelaert, J. R.; Best-Belpomme, M. et al

in Biochemical Journal (2001), 360(Pt 2), 321-33

The transcription factor, nuclear factor kappa B (NF-kappa B), is activated by various stimuli including cytokines, radiation, viruses and oxidative stress. Here we show that, although induction with H(2 ... [more ▼]

The transcription factor, nuclear factor kappa B (NF-kappa B), is activated by various stimuli including cytokines, radiation, viruses and oxidative stress. Here we show that, although induction with H(2)O(2) gives rise to NF-kappa B nuclear translocation in both lymphocyte (CEM) and monocyte (U937) cells, it leads only to the production of mRNA species encoding interleukin-8 (IL-8) and macrophage inflammatory protein 1 alpha in U937 cells. Under similar conditions these mRNA species are not observed in CEM cells. With the use of a transient transfection assay of U937 cells transfected with reporter constructs of the IL-8 promoter and subsequently treated with H(2)O(2), we show that (1) IL-8-promoter-driven transcription is stimulated in both U937 and CEM cells and (2) the NF-kappa B site is crucial for activation because its deletion abolishes activation by H(2)O(2). The production of IL-8 mRNA in U937 cells is inhibited by the NF-kappa B inhibitors clasto-lactacystin-beta-lactone and E-64D (l-3-trans-ethoxycarbonyloxirane-2-carbonyl-L-leucine-3-methyl amide) but requires protein synthesis de novo. Moreover, inhibition of the p38 mitogen-activated protein kinase also decreases the IL-8 mRNA up-regulation mediated by H(2)O(2). Taken together, these results show the importance of post-transcriptional events controlled by a p38-dependent pathway in the production of IL-8 mRNA in U937. The much lower activation of p38 in CEM cells in response to H(2)O(2) could explain the lack of stabilization of IL-8 mRNA in these cells. [less ▲]

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See detailNf-Kappab Activation in Response to Toxical and Therapeutical Agents: Role in Inflammation and Cancer Treatment
Bours, Vincent ULg; Bonizzi, Giuseppina; Bentires-Alj, Mohamed et al

in Toxicology (2000), 153(1-3), 27-38

The NF-kappaB transcription factor is ubiquitously expressed and controls the expression of a large number of genes. Experimental data clearly indicate that NF-kappaB is a major regulator of the ... [more ▼]

The NF-kappaB transcription factor is ubiquitously expressed and controls the expression of a large number of genes. Experimental data clearly indicate that NF-kappaB is a major regulator of the inflammatory reaction by controlling the expression of pro-inflammatory molecules in response to cytokines, oxidative stress and infectious agents. We demonstrated that NF-kappaB activation by IL-1beta follows three distinct cell-specific pathways. Moreover, our studies indicated that in one model of inflammatory diseases, horse recurrent airway obstruction (RAO), the extent of NF-kappaB basal activity correlates with pulmonary dysfunction. Another role of NF-kappaB activity protects cancer cells against apoptosis and could participate in the resistance to cancer treatment. However, we did not observe any increased cytotoxicity after treatment with anticancer drugs or TNF-alpha of cells expressing a NF-kappaB inhibitor. Therefore, we can conclude that the inhibition of apoptosis by NF-kappaB is likely to be cell type and stimulus-dependent. Further studies are required to determine whether NF-kappaB could be a target for anticancer treatments. [less ▲]

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See detailGene activation by varicella-zoster virus IE4 protein requires its dimerization and involves both the arginine-rich sequence, the central part, and the carboxyl-terminal cysteine-rich region
Baudoux, Laurence; Defechereux, Patricia; Rentier, Bernard ULg et al

in Journal of Biological Chemistry (2000), 275(42), 32822-32831

Varicella-zoster virus (VZV) open reading frame 4-encoded protein (IE4) possesses transactivating properties for VZV genes as well as for those of heterologous viruses. Since most transcription factors ... [more ▼]

Varicella-zoster virus (VZV) open reading frame 4-encoded protein (IE4) possesses transactivating properties for VZV genes as well as for those of heterologous viruses. Since most transcription factors act as dimers, IE4 dimerization was studied using the mammalian two-hybrid system. Introduction of mutations in the IE4 open reading frame demonstrated that both the central region and the carboxyl-terminal cysteine-rich domain were important for efficient dimerization. Within the carboxyl-terminal domain, substitution of amino acids encompassing residues 443-447 totally abolished dimerization. Gene activation by IE4 was studied by transient transfection with an IE4 expression plasmid and a reporter gene under the control of either the human immunodeficiency virus, type 1, long terminal repeat or the VZV thymidine kinase promoter. Regions of IE4 important for dimerization were also shown to be crucial for transactivation. In addition, the arginine-rich domains Rb and Re of the amino-terminal region were also demonstrated to be important for transactivation, whereas the Ra domain as well as an acidic and bZIP-containing regions were shown to be dispensable for gene transactivation. A nucleocytoplasmic shuttling of IE4 has also been characterized, involving a nuclear localization signal identified within the Rb domain and a nuclear export mechanism partially depending on Crm-1. [less ▲]

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See detailActivation of the NF-kappaB transcription factor by Camptothecin in HeLa cells
Habraken, Yvette ULg; Piret, Bernard; Piette, Jacques ULg

Poster (2000, February 22)

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See detailCell Type-Specific Role for Reactive Oxygen Species in Nuclear Factor-Kappab Activation by Interleukin-1
Bonizzi, G.; Piette, Jacques ULg; Merville, Marie-Paule ULg et al

in Biochemical Pharmacology (2000), 59(1), 7-11

The role of reactive oxygen intermediates (ROIs) in nuclear factor-kappaB (NF-kappaB) activation remains a matter of controversy. We have studied whether ROIs played any role in NF-kappaB induction by ... [more ▼]

The role of reactive oxygen intermediates (ROIs) in nuclear factor-kappaB (NF-kappaB) activation remains a matter of controversy. We have studied whether ROIs played any role in NF-kappaB induction by interleukin-1beta (IL-1beta) in different cell types. Our studies indicated three different pathways. IL-1beta stimulation of lymphoid cells generates ROIs, which are required for IkappaB-alpha degradation and NF-kappaB activation. The source of these ROIs is the 5-lipoxygenase (5-LOX) enzyme. In monocytic cells, ROIs are also produced in response to IL-1beta and necessary for NF-kappaB induction, but their source appears to be the NADPH oxidase complex. Finally, epithelial cells do not generate ROIs after IL-1beta stimulation, but do rapidly activate NF-kappaB. Interestingly, transfection of epithelial cells with the 5-LOX and 5-LOX activating protein expression vectors restored ROI production and ROI-dependent NF-kappaB activation in response to IL-1beta. Our data thus indicate that ROIs are cell type-specific second messengers for NF-kappaB induction by IL-1beta. [less ▲]

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See detailCrucial role of the amino-terminal tyrosine residue 42 and the carboxy-terminal PEST domain of IkappaBalpha in NF-kappaB activation by an oxidative stress
Schoonbroodt, Sonia; Ferreira, V.; Best-Belpomme, Martin et al

in Journal of Immunology (2000)

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See detailRole of Nuclear Factor-Kappa B in Colon Cancer Cell Apoptosis Mediated by Aminopyropheophorbide Photosensitization
Matroule, J. Y.; Hellin, A. C.; Morliere, P. et al

in Photochemistry & Photobiology (1999), 70(4), 540-8

Aminopyropheophorbide (APP) is a second generation of photosensitizer for photodynamic therapy (PDT). We demonstrated that APP strongly absorbed red light and, after being taken up by colon cancer cells ... [more ▼]

Aminopyropheophorbide (APP) is a second generation of photosensitizer for photodynamic therapy (PDT). We demonstrated that APP strongly absorbed red light and, after being taken up by colon cancer cells (HCT-116 cells), was localized in cytoplasmic and internal membranes but not in mitochondria. The APP-mediated photosensitization was cytotoxic for HCT-116 cells through an induction of apoptosis. Indeed, DNA fragmentation (DNA laddering and terminal deoxyuridine nick-end labeling) and chromatin condensation (4',6-diamidine-2'-phenylindole staining) could be visualized soon after photosensitization. Because nuclear factor (NF)-kappa B is involved in the response to many photosensitizers, we also demonstrated its nuclear translocation in two waves: a rapid and transient one, followed by a slow and sustained phase. The NF-kappa B turned out to be involved in an antiapoptotic response to APP-mediated photosensitization because the HCT-116 cell line expressing the dominant negative mutant of inhibitor-kappa B alpha was more sensitive to apoptosis as measured by DNA fragmentation and caspase activation. These data unambiguously show that a membrane-located photosensitizer can lead to effective apoptosis, reinforcing the idea that PDT can be an effective means to eradicate colon cancer cells. [less ▲]

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See detailRole of the Protein Kinase C Lambda/Iota Isoform in Nuclear Factor-Kappab Activation by Interleukin-1beta or Tumor Necrosis Factor-Alpha: Cell Type Specificities
Bonizzi, G.; Piette, Jacques ULg; Haterte, Stéphanie ULg et al

in Biochemical Pharmacology (1999), 57(6), 713-20

It has previously been reported that distinct signaling pathways can lead to nuclear factor (NF)-kappaB activation following stimulation of different cell types with inflammatory cytokines. As the role of ... [more ▼]

It has previously been reported that distinct signaling pathways can lead to nuclear factor (NF)-kappaB activation following stimulation of different cell types with inflammatory cytokines. As the role of atypical protein kinase C (PKC) isoforms in NF-kappaB activation remains a matter of controversy, we investigated whether this role might be cell type-dependent. Immunoblots detected atypical PKC expression in all the analyzed cell lines. The PKC inhibitor calphostin C inhibited NF-kappaB activation by tumor necrosis factor (TNF)-alpha or interleukin (IL)-1beta in Jurkat or NIH3T3 cells but not in MCF7 A/Z cells. Cell transfections with a PKC lambda/iota dominant negative mutant abolished TNF-alpha-induced NF-kappaB-dependent transcription in NIH3T3 and Jurkat cells but not in MCF7 A/Z cells. Similarly, the same mutant blocked NF-kappaB-dependent transactivation after IL-1beta stimulation of NIH3T3 cells, but was ineffective after IL-1beta treatment of MCF7 A/Z cells. In MCF7 A/Z cells, however, the PKC lambda/iota dominant negative mutant could abolish transactivation of an AP-1-dependent reporter plasmid after stimulation with TNF-alpha but not with IL-1beta. These data thus confirm that transduction pathways for NF-kappaB activation after cell stimulation with TNF-alpha or IL-1beta are cell-type specific and that atypical PKC isoforms participate in this pathway in NIH3T3 and Jurkat cells. [less ▲]

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See detailReactive Oxygen Intermediate-Dependent Nf-Kappab Activation by Interleukin-1beta Requires 5-Lipoxygenase or Nadph Oxidase Activity
Bonizzi, Giuseppina; Piette, Jacques ULg; Haterte, Stéphanie ULg et al

in Molecular & Cellular Biology (1999), 19(3), 1950-60

We previously reported that the role of reactive oxygen intermediates (ROIs) in NF-kappaB activation by proinflammatory cytokines was cell specific. However, the sources for ROIs in various cell types are ... [more ▼]

We previously reported that the role of reactive oxygen intermediates (ROIs) in NF-kappaB activation by proinflammatory cytokines was cell specific. However, the sources for ROIs in various cell types are yet to be determined and might include 5-lipoxygenase (5-LOX) and NADPH oxidase. 5-LOX and 5-LOX activating protein (FLAP) are coexpressed in lymphoid cells but not in monocytic or epithelial cells. Stimulation of lymphoid cells with interleukin-1beta (IL-1beta) led to ROI production and NF-kappaB activation, which could both be blocked by antioxidants or FLAP inhibitors, confirming that 5-LOX was the source of ROIs and was required for NF-kappaB activation in these cells. IL-1beta stimulation of epithelial cells did not generate any ROIs and NF-kappaB induction was not influenced by 5-LOX inhibitors. However, reintroduction of a functional 5-LOX system in these cells allowed ROI production and 5-LOX-dependent NF-kappaB activation. In monocytic cells, IL-1beta treatment led to a production of ROIs which is independent of the 5-LOX enzyme but requires the NADPH oxidase activity. This pathway involves the Rac1 and Cdc42 GTPases, two enzymes which are not required for NF-kappaB activation by IL-1beta in epithelial cells. In conclusion, three different cell-specific pathways lead to NF-kappaB activation by IL-1beta: a pathway dependent on ROI production by 5-LOX in lymphoid cells, an ROI- and 5-LOX-independent pathway in epithelial cells, and a pathway requiring ROI production by NADPH oxidase in monocytic cells. [less ▲]

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See detailOverview of the replication cycle of varicella-zoster virus
Sadzot-Delvaux, Catherine ULg; Baudoux, Laurence; Defechereux, Patricia et al

in Schmidt, A.; Wolff, M. H.; Schünemann, S. (Eds.) Varicella-Zoster Virus : Molecular Biology, Pathogenesis and Clinical Aspects (1999)

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See detailActivation of the human immunodeficiency virus long terminal repeat by varicella-zoster virus IE4 protein requires nuclear factor-kB and involves both the amino-terminal and the carboxyl-terminal cysteine-rich region
Defechereux-Thibaut de Maisières, Patricia; Baudoux-Tebache, Laurence; Merville, Marie-Paule ULg et al

in Journal of Biological Chemistry (1998), 273(22), 13636-13644

Varicella-zoster virus open reading frame 4-encoded protein (IE4) possesses transactivating properties for varicella-zoster virus genes as well as for those of heterologous viruses such as the human ... [more ▼]

Varicella-zoster virus open reading frame 4-encoded protein (IE4) possesses transactivating properties for varicella-zoster virus genes as well as for those of heterologous viruses such as the human immunodeficiency virus type 1 (HIV-1). Mechanisms of HIV-1 LTR (long terminal repeat) transactivation were investigated in HeLa cells transiently transfected with an IE4 expression plasmid and a CAT reporter gene under the control of the HIV-1 LTR. These results demonstrated that IE4-mediated transactivation of the HIV-1 LTR in HeLa cells required transcription factor kappaB (NF-kappaB). Using the gel retardation assay, it was shown that transfection of the IE4 expression vector in HeLa cells was not associated with induction of NF-kappaB under the p50.p65 heterodimeric form and that no direct binding of IE4 to the kappaB sites could be detected. Both Western blot and immunofluorescence analyses suggested that the ability of IE4 to activate transcription through kappaB motives was not connected with its capacity to override the inhibitory activities of IkappaB-alpha or p105. Finally, in vitro protein-protein interactions involving IE4 and basal transcription factors such as TATA-binding protein and transcription factor IIB were carried out. A direct interaction between IE4 and TATA-binding protein or transcription factor IIB components of the basal complex of transcription was evidenced, as well as binding to the p50 and p65 NF-kappaB subunits. Mutagenesis analysis of IE4 indicated that the COOH-terminal cysteine-rich and arginine-rich regions (residues 82-182) were critical for transactivation, whereas the first 81 amino acids appeared dispensable. Moreover, the arginine-rich region is required for the in vitro binding activity, whereas the COOH-terminal end did not appear essential. [less ▲]

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See detailNF-kappaB: an important transcription factor in photobiology
Legrand-Poels, Sylvie ULg; Schoonbroodt, Sonia; Matroule, Jean-Yves et al

in Journal of Photochemistry and Photobiology B : Biology (1998)

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