Evaluation of ER stress induced by DNFB in Dendritic cells
authors Andreia Luís
supervisors Bruno Neves, Maria Teresa Cruz
thesis type Master Thesis
abstract The capacity of dendritic cells (DC) to initiate and modulate immune responses, namely allergic contact dermatitis (ACD), is tightly dependent on their activation/maturation state. Molecular mechanisms driving skin sensitizersinduced DC maturation are not yet completely unrevealed, however initial danger signals such as the generation of reactive oxygen species (ROS) were shown to play an important role. In recent years innumerous evidences established a close link between ROS production, endoplasmic reticulum (ER) stress and the pathogenesis of several inflammatory diseases. Therefore, we analyzed in this work the ability of the strong sensitizer DNFB to trigger ER stress in DC and the concomitant consequences to the immunobiology of these cells. Our results revealed that DNFB induces a rapid and sustained phosphorylation of the Eukaryotic translation initiation factor 2α (eIF2α), the up regulation of ATF4 and a post translational modification at the major ER chaperone GRP78. These effects were dose dependent and partially reverted by the antioxidant N-acetylcysteine, indicating that cellular redox imbalance is in the origin of evoked ER stress. Treatment of cells with the ER chemical chaperone 4 phenylbutyric acid (4-PBA) caused an increase in DNFB-induced apoptosis while pretreatment with salubrinal, an eIF2α dephosphorylation selective inhibitor, caused the opposite effect. Exacerbation of DNFB-induced eIF2α phosphorylation by salubrinal also caused a strong increase in the transcription of detoxifying genes such as HMOX and of pro-inflammatory cytokine IL-8 while 4-PBA completely abrogated these effects. Overall, our results indicate that DNFB activation of eIF2α/ATF4 stress pathways in DC strongly contributes to generation of a pro-inflammatory microenvironment and is crucial to the transcription of genes involved in remediation of cell redox imbalance.
year published 2013
link http://ria.ua.pt/handle/10773/11670