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See detailS Phase Dependence and Involvement of Nf-Kappab Activating Kinase to Nf-Kappab Activation by Camptothecin
Habraken, Yvette ULg; Piret, Bernard; Piette, Jacques ULg

in Biochemical Pharmacology (2001), 62(5), 603-16

Camptothecin (CPT) and derivatives are topoisomerase I poisons currently used as anticancer drugs. Their cytotoxicity is maximal for cells in S phase. Using asynchronous and S phase-synchronized HeLa ... [more ▼]

Camptothecin (CPT) and derivatives are topoisomerase I poisons currently used as anticancer drugs. Their cytotoxicity is maximal for cells in S phase. Using asynchronous and S phase-synchronized HeLa cells, we showed that both the nuclear factor-kappaB (NF-kappaB) activation and its transcriptional activity, induced by CPT treatment, are enhanced in S phase cells. After CPT treatment, NF-kappaB activation reached a maximum within 2-3 hr and was still detectable after 24 hr. The nature of the complex evolved with time, forming mostly p50/p65 after 2 hr to almost exclusively p52 after 24 hr. In HeLa cells, the different steps of the induction were readily observable in S phase synchronized cells, whereas they were barely noticeable in a randomly growing cell population. The signal progressed through the activation of the IKK complex, the phosphorylation of IkappaBalpha, and the degradation of phosphorylated-IkappaBalpha and -IkappaBbeta. The stable expression of wild-type HA-tagged-IkappaBalpha or mutated HA-tagged-IkappaBalpha (S32,36A) allowed us to confirm the essential role of Ser32 and Ser36. NF-kappaB-activating kinase (NIK) could play a role upstream of the IKK complex, as the transient expression of a kinase inactive mutant NIK(K429,430A) abolished the activation of NF-kappaB by CPT. A kinase inactive mutant of mitogen-activated protein/ERK kinase kinase 1 (MEKK1), another kinase susceptible of acting upstream of the signalsome, did not. Cytotoxicity studies with clonal populations expressing different amounts of wild-type or mutated IkappaBalpha revealed that the overexpression of wild-type IkappaBa in large amount increases the sensitivity of HeLa cells to CPT more efficiently than a lower level of expression of non-phosphorylable IkappaBalpha. [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 detailImpairment of mitochondrial functions abolishes NF-kappaB activation by an oxidative stress
Josse, Claire ULg; Legrand-Poels, Sylvie ULg; Piret, Bernard et al

in Free Radical Biology & Medicine (1998)

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See detailMultiple Redox Regulation in Nf-Kappab Transcription Factor Activation
Piette, Jacques ULg; Piret, Bernard; Bonizzi, Giuseppina et al

in Biological Chemistry (1997), 378(11), 1237-45

The well-known Rel/NF-kappaB family of vertebrate transcription factors comprises a number of structurally related, interacting proteins that bind DNA as dimers and whose activity is regulated by ... [more ▼]

The well-known Rel/NF-kappaB family of vertebrate transcription factors comprises a number of structurally related, interacting proteins that bind DNA as dimers and whose activity is regulated by subcellular location. This family includes many members (p50, p52, RelA, RelB, c-Rel, ...), most of which can form DNA-binding homo- or hetero-dimers. All Rel proteins contain a highly conserved domain of approximately 300 amino-acids, called the Rel homology domain (RH), which contains sequences necessary for the formation of dimers, nuclear localization, DNA binding and IkappaB binding. Nuclear expression and consequent biological action of the eukaryotic NF-kappaB transcription factor complex are tightly regulated through its cytoplasmic retention by ankyrin-rich inhibitory proteins known as IkappaB. The IkappaB proteins include a group of related proteins that interact with Rel dimers and regulate their activities. The interaction of a given IkappaB protein with a Rel complex can affect the Rel complex in distinct ways. In the best characterized example, IkappaB-alpha interacts with a p50/RelA (NF-kappaB) heterodimer to retain the complex in the cytoplasm and inhibit its DNA-binding activity. The NF-kappaB/IkappaB-alpha complex is located in the cytoplasm of most resting cells, but can be rapidly induced to enter the cell nucleus. Upon receiving a variety of signals, many of which are probably mediated by the generation of reactive oxygen species (ROS), IkappaB-alpha undergoes phosphorylation at serine residues by a ubiquitin-dependent protein kinase, is then ubiquitinated at nearby lysine residues and finally degraded by the proteasome, probably while still complexed with NF-kappaB. Removal of IkappaB-alpha uncovers the nuclear localization signals on subunits of NF-kappaB, allowing the complex to enter the nucleus, bind to DNA and affect gene expression. Like proinflammatory cytokines (e.g. IL-1, TNF), various ROS (peroxides, singlet oxygen, ...) as well as UV (C to A) light are capable of mediating NF-kappaB nuclear translocation, while the sensor molecules which are sensitive to these agents and trigger IkappaB-alpha proteolysis are still unidentified. We also show that a ROS-independent mechanism is activated by IL-1beta in epithelial cells and seems to involve the acidic sphingomyelinase/ceramide transduction pathway. [less ▲]

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See detailInvolvement of different transduction pathways in NF-kappaB activation by several inducers
Legrand-Poels, Sylvie ULg; Zecchinon, Laurent; Piret, Bernard et al

in Free Radical Research (1997)

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See detailInterleukin-1 Beta Induces Nuclear Factor Kappa B in Epithelial Cells Independently of the Production of Reactive Oxygen Intermediates
Bonizzi, Giuseppina; Dejardin, Emmanuel ULg; Piret, Bernard et al

in European Journal of Biochemistry (1996), 242(3), 544-9

A large body of work has been devoted to tumor necrosis factor alpha or interleukin-1 beta (IL-1 beta) signaling leading to the activation of the transcription factor nuclear factor-kappa B (NF-kappa B ... [more ▼]

A large body of work has been devoted to tumor necrosis factor alpha or interleukin-1 beta (IL-1 beta) signaling leading to the activation of the transcription factor nuclear factor-kappa B (NF-kappa B) in various cell types. Several studies have indicated that NF-kappa B activation depends strictly on the production of reactive oxygen intermediates. In this report, we first demonstrated that IL-1 beta is a potent activator of NF-kappa B in various epithelial transformed cell lines (OVCAR-3, SKOV-3, MCF7 A/Z). In these cells, IL-1 beta rapidly induces NF-kappa B through a complete degradation of I kappa B-alpha, while H2O2 activates NF-kappa B with slower kinetics through a partial degradation of I kappa B-alpha, p100 and p105. We showed that IL-1 beta-mediated induction of NF-kappa B in OVCAR-3 and in other epithelial cell lines does not proceed through the production of reactive oxygen intermediates, while the same cytokine activates NF-kappa B in lymphoid cells through the intracellular generation of H2O2. Our study demonstrated that several signaling pathways lead to the activation of NF-kappa B, following IL-1 beta treatment in different cell types. [less ▲]

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See detailTranscription factor NF-kB is activated by photosensitization generating oxidative DNA damages
Legrand-Poels, Sylvie ULg; Bours, Vincent ULg; Piret, Bernard et al

in Journal of Biological Chemistry (1995), 270(12), 6925-6934

Reactive oxygen intermediates like hydrogen peroxide (H2O2) have been shown to serve as messengers in the induction of NF-kappa B and, then, in the activation and replication of human immunodeficiency ... [more ▼]

Reactive oxygen intermediates like hydrogen peroxide (H2O2) have been shown to serve as messengers in the induction of NF-kappa B and, then, in the activation and replication of human immunodeficiency virus (HIV)-1 in human cells. Because H2O2 can be converted into the highly reactive OH. at various locations inside the cells, we started to investigate the generation of Reactive oxygen intermediates by photosensitization. This technique is based on the use of a photosensitizer which is a molecule absorbing visible light and which can be located at various sites inside the cell depending on its physicochemical properties. In this work, we used proflavine (PF), a cationic molecule having a high affinity for DNA, capable of intercalating between DNA base pairs. Upon visible light irradiation, intercalated PF molecules oxidize guanine residues and generate DNA single-strand breaks. In lymphocytes or monocytes latently infected with HIV-1 (ACH-2 or U1, respectively), this photosensitizing treatment induced a cytotoxicity, an induction of NF-kappa B, and a reactivation of HIV-1 in cells surviving the treatment. NF-kappa B induction by PF-mediated photosensitization was not affected by the presence of N-acetyl-L-cysteine while strong inhibition was recorded when the induction was triggered by H2O2 or by phorbol 12-myristate 13-acetate. Another transcription factor like AP-1 is less activated by this photosensitizing treatment. In comparison with other inducing treatments, such as phorbol 12-myristate 13-acetate or tumor necrosis factor alpha, the activation of NF-kappa B is slow, being optimal 120 min after treatment. These kinetic data were obtained by following, on the same samples, both the appearance of NF-kappa B in the nucleus and the disappearance of I kappa B-alpha in cytoplasmic extracts. These data allow us to postulate that signaling events, initiated by DNA oxidative damages, are transmitted into the cytoplasm where the inactive NF-kappa B factor is resident and allow the translocation of p50/p65 subunits of NF-kappa B to the nucleus leading to HIV-1 gene expression. [less ▲]

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See detailNF-kappaB transcription factor and human immunodeficiency virus type 1 (HIV-1) are activated by methylene blue photosensitization
Piret, Bernard; Legrand-Poels, Sylvie ULg; Sappey, Christine et al

in European Journal of Biochemistry (1995)

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See detailHIV-1 and NF-kappaB activation by photo-oxidative stress
Piette, Jacques ULg; Legrand-Poels, Sylvie ULg; Piret, Bernard

in Photochemistry & Photobiology (1995)

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