Phosphorylation of p65(RelA) on Ser547 by ATM represses NF-κB-dependent transcription of specific genes after genotoxic stress.

in PLoS ONE (2012)

The NF-κB pathway is involved in immune and inflammation responses, proliferation, differentiation and cell death or survival. It is activated by many external stimuli including genotoxic stress. DNA ... [more ▼]

The NF-κB pathway is involved in immune and inflammation responses, proliferation, differentiation and cell death or survival. It is activated by many external stimuli including genotoxic stress. DNA double-strand breaks activate NF-κB in an ATM-dependent manner. In this manuscript, a direct interaction between p65(RelA) and the N-terminal extremity of ATM is reported. We also report that only one of the five potential ATM-(S/T)Q target sites present in p65, namely Ser547, is specifically phosphorylated by ATM in vitro. A comparative transcriptomic analysis performed in HEK-293 cells expressing either wild-type HA-p65 or a non-phosphorylatable mutant HA-p65S547A identified several differentially transcribed genes after an etoposide treatment (e.g. IL8, A20, SELE). The transcription of these genes is increased in cells expressing the mutant. Substitution of Ser547 to alanine does not affect p65 binding abilities on the κB site of the IL8 promoter but reduces p65 interaction with HDAC1. Cells expressing p65S547A have a higher level of histone H3 acetylated on Lys9 at the IL8 promoter, which is in agreement with the higher gene induction observed. These results indicate that ATM regulates a sub-set of NF-κB dependent genes after a genotoxic stress by direct phosphorylation of p65. [less ▲]

Proinflammatory Cytokines Induce Bronchial Hyperplasia and Squamous Metaplasia in Smokers: Implications for chronic obstructive pulmonary disease therapy.

in American Journal of Respiratory Cell and Molecular Biology (2012), 47(1), 67-79

Tracheobronchial squamous metaplasia is common in smokers and is associated with both airway obstruction in chronic obstructive pulmonary disease (COPD) and increased risk of lung cancer. Whereas this ... [more ▼]

Tracheobronchial squamous metaplasia is common in smokers and is associated with both airway obstruction in chronic obstructive pulmonary disease (COPD) and increased risk of lung cancer. Whereas this reversible epithelial replacement is almost always observed in association with chronic inflammation, the role of inflammatory mediators in the pathogenesis of squamous metaplasia is still unclear. In the present study, we investigated the implication of cigarette smoke-mediated pro-inflammatory cytokine up-regulation in the development and treatment of tracheobronchial epithelial hyperplasia and squamous metaplasia. By using immunohistological techniques, we showed a higher epithelial expression of TNFalpha, IL-1beta and IL-6 as well as an activation of NF-kappaB and AP-1/MAPK signalling pathways in the respiratory tract of smoking patients compared to the normal ciliated epithelium of non-smoking patients. In addition, we demonstrated that these signalling pathways strongly influence the proliferation and the differentiation state of in vitro generated normal human airway epithelial basal cells. Finally, we exposed mice to cigarette smoke for 16 weeks and demonstrated that anti-TNFalpha (etanercept), anti-IL-1beta (anakinra) and/or anti-IL-6R (tocilizumab) therapies significantly reduced epithelial hyperplasia and squamous metaplasia development. These data highlight the importance of soluble inflammatory mediators in the pathogenesis of tracheobronchial squamous metaplasia. Therefore, administration of pro-inflammatory cytokine antagonists may have clinical application in the management of COPD patients. [less ▲]

NF-kappaB inhibition improves the sensitivity of human glioblastoma cells to 5-aminolevulinic acid-based photodynamic therapy.

in Biochemical Pharmacology (2011)

Glioblastoma constitute the most frequent and deadliest brain tumors of astrocytic origin. They are very resistant to all current therapies and are associated with a huge rate of recurrence. In most cases ... [more ▼]

Glioblastoma constitute the most frequent and deadliest brain tumors of astrocytic origin. They are very resistant to all current therapies and are associated with a huge rate of recurrence. In most cases, this type of tumor is characterized by a constitutive activation of the nuclear factor-kappaB (NF-kappaB). This factor is known to be a key regulator of various physiological processes such as inflammation, immune response, cell growth or apoptosis. In the present study, we explored the role of NF-kappaB activation in the sensitivity of human glioblastoma cells to a treatment by 5-aminolevulinic acid (5-ALA)-based photodynamic therapy (PDT). 5-ALA is a physiological compound widely used in PDT as well as in tumor photodetection (PDD). Our results show that inhibition of NF-kappaB improves glioblastoma cell death in response to 5-ALA-PDT. We then studied the molecular mechanisms underlying the cell death induced by PDT combined or not with NF-kappaB inhibition. We found that apoptosis was induced by PDT but in an incomplete manner and that, unexpectedly, NF-kappaB inhibition reduced its level. Oppositely PDT mainly induces necrosis in glioblastoma cells and NF-kappaB is found to have anti-necrotic functions in this context. The autophagic flux was also enhanced as a result of 5-ALA-PDT and we demonstrate that stimulation of autophagy acts as a pro-survival mechanism confering protection against PDT-mediated necrosis. These data point out that 5-ALA-PDT has an interesting potential as a mean to treat glioblastoma and that inhibition of NF-kappaB renders glioblastoma cells more sensitive to the treatment. [less ▲]

NF-kappaB activation by DNA double strand breaks is MDC1 and 53BP1 dependent

Poster (2010, March 08)

MageD2, a newly identified ATM substrate, regulates the DNA damage induced transcriptional response

Poster (2010, January 27)

NF-kappaB activation by DNA double strand breaks is MDC1 and 53BP1 dependent

Poster (2009, March 08)

Newly identified biologically active and proteolysis-resistant VEGF-A isoform VEGF111 is induced by genotoxic agents

in Journal of Cell Biology (2007), 179(6), 1261-1273

Ultraviolet B and genotoxic drugs induce the expression of a vascular endothelial growth factor A (VEGF-A) splice variant (VEGF111) encoded by exons 1-4 and 8 in many cultured cells. Although not detected ... [more ▼]

Ultraviolet B and genotoxic drugs induce the expression of a vascular endothelial growth factor A (VEGF-A) splice variant (VEGF111) encoded by exons 1-4 and 8 in many cultured cells. Although not detected in a series of normal human and mouse tissue, VEGF111 expression is induced in MCF-7 xenografts in nude mice upon treatment by camptothecin. The skipping of exons that contain proteolytic cleavage sites and extracellular matrix-binding domains makes VEGF111 diffusible and resistant to proteolysis. Recombinant VEGF111 activates VEGF receptor 2 (VEGF-R2) and extracellularly regulated kinase 1/2 in human umbilical vascular endothelial cells and porcine aortic endothelial cells expressing VEGF-R2. The mitogenic and chemotactic activity and VEGF111's ability to promote vascular network formation during embyonic stem cell differentiation are similar to those of VEGF121 and 165. Tumors in nude mice formed by HEK293 cells expressing VEGF111 develop a more widespread network of numerous small vessels in the peritumoral tissue than those expressing other isoforms. Its potent angiogenic activity and remarkable resistance to proteolysis makes VEGF111 a potential adverse factor during chemotherapy but a beneficial therapeutic tool for ischemic diseases. [less ▲]

NF-kappa B activation by double-strand breaks

in Biochemical Pharmacology (2006), 72(9), 1132-1141

Cellular response to DNA damage is complex and relies on the simultaneous activation of different networks. It involves DNA damage recognition, repair, and induction of signalling cascades leading to cell ... [more ▼]

Cellular response to DNA damage is complex and relies on the simultaneous activation of different networks. It involves DNA damage recognition, repair, and induction of signalling cascades leading to cell cycle checkpoint activation, apoptosis, and stress related responses. The fate of damaged cells depends on the balance between pro- and antiapoptotic signals. in this decisive life or death choice, the transcription factor NF-kappa B has emerged as a prosurvival actor in most cell types. As corollary, it appears to be associated with tumorigenic process and resistance to therapeutic strategies as it protects cancerous cells from death. in this review, we will focus on NF-kappa B activation by double-strand breaks inducing agents, such as ionizing radiation and DNA topoisomerase I and II inhibitors routinely used in cancer therapy. Coinciding with the 20th anniversary of the NF-kappa B discovery, major steps of the DSB-triggered cascade have been recently identified. Two parallel cascades are necessary for NF-kappa B activation. The first one depends on ATM (activated by double-strand breaks) and the second on PIDD (activated by an unknown stress signal). The phosphorylation of NEMO by ATM is the point of convergence of these two cascades. The identification of ATM/NEMO complex as the long searched "nuclear to cytoplasm" signal leading to IKK activation is also a major piece of the puzzle. The knowledge of the precise steps leading to DSB-initiated NF kappa B activation will allow the development of specific blocking compounds reducing its prosurvival function. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

Nitric oxide-related products and myeloperoxidase in bronchoalveolar lavage fluids from patients with ALI activate NF-kappa B in alveolar cells and monocytes.

in Vascular Pharmacology (2005), 43(6), 425-33

An increased production of NO* and peroxynitrite in lungs has been suspected during acute lung injury (ALI) in humans, and recent studies provided evidence for an alveolar production of nitrated compounds ... [more ▼]

An increased production of NO* and peroxynitrite in lungs has been suspected during acute lung injury (ALI) in humans, and recent studies provided evidence for an alveolar production of nitrated compounds. We observed increased concentrations of nitrites/nitrates, nitrated proteins and markers of neutrophil degranulation (myeloperoxidase, elastase and lactoferrine) in the fluids recovered from bronchoalveolar lavage fluids (BALF) of patients with ALI and correlated these changes to the number of neutrophils and the severity of the ALI. We also observed that BALFs stimulated the DNA-binding activity of the nuclear transcription factor kappa B (NF-kappaB) as detected by electrophoretic mobility shift assay in human alveolar cells (A549) and monocytes (THP1). The level of activation of the NF-kappaB-binding activity was correlated to the concentration of nitrated proteins and myeloperoxidase. Furthermore, in vitro studies confirmed that NO*-derived species (peroxynitrite and nitrites) and the neutrophil enzyme myeloperoxidase by themselves increased the activation of NF-kappaB, thereby arguing for an in vivo pathogenetic role of NO*-related products and neutrophil enzymes to human ALI. [less ▲]

Differential involvement of the Mre11/Rad50/NBS (M/R/N) complex, BRCA1 and MLH1 in NF-kappaB activation by camptothecin and X-ray

Poster (2004, January 11)