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Geranylgeranylacetone (GGA) exerts cytoprotective activity against various toxic stressors via the thioredoxin (TRX) redox system; however, its effect on skin inflammation and molecular mechanism on inducing the TRX of GGA is still unknown. We investigated the effects of GGA in a murine irritant contact dermatitis (ICD) model induced by croton oil. Both a topical application and oral administration of GGA induced TRX production and Nrf2 activation. GGA ameliorated ear swelling, neutrophil infiltration, and inhibited the expression of TNF-α, IL-1β, GM-CSF, and 8-OHdG. GGA's cytoprotective effect was stronger orally than topically in mice. In vitro studies also showed that GGA suppressed the expression of NLRP3, TNF-α, IL-1β, and GM-CSF and scavenged ROS in PAM212 cells after phorbol myristate acetate stimulation. Moreover, GGA induced endogenous TRX production and Nrf2 nuclear translocation in PAM212 cells (dependent on the presence of ROS) and activated the PI3K-Akt signaling pathway. GGA significantly downregulated thioredoxin-interacting protein (TXNIP) levels in PAM212 cells treated with or without Nrf2 siRNA. After knocking down Nrf2 in PAM212 cells, the effect of GGA on TRX induction was significantly inhibited. This suggests that GGA suppress ICD by inducing endogenous TRX, which may be regulated by PI3K/Akt/Nrf2 mediation of the TRX redox system. [ABSTRACT FROM AUTHOR]

Geranylgeranylacetone (GGA) exerts cytoprotective activity against various toxic stressors via the thioredoxin (TRX) redox system; however, its effect on skin inflammation and molecular mechanism on inducing the TRX of GGA is still unknown. We investigated the effects of GGA in a murine irritant contact dermatitis (ICD) model induced by croton oil. Both a topical application and oral administration of GGA induced TRX production and Nrf2 activation. GGA ameliorated ear swelling, neutrophil infiltration, and inhibited the expression of TNF-α, IL-1β, GM-CSF, and 8-OHdG. GGA’s cytoprotective effect was stronger orally than topically in mice. In vitro studies also showed that GGA suppressed the expression of NLRP3, TNF-α, IL-1β, and GM-CSF and scavenged ROS in PAM212 cells after phorbol myristate acetate stimulation. Moreover, GGA induced endogenous TRX production and Nrf2 nuclear translocation in PAM212 cells (dependent on the presence of ROS) and activated the PI3K-Akt signaling pathway. GGA significantly downregulated thioredoxin-interacting protein (TXNIP) levels in PAM212 cells treated with or without Nrf2 siRNA. After knocking down Nrf2 in PAM212 cells, the effect of GGA on TRX induction was significantly inhibited. This suggests that GGA suppress ICD by inducing endogenous TRX, which may be regulated by PI3K/Akt/Nrf2 mediation of the TRX redox system.

Oxidative stress and decline in cellular redox regulation have been hypothesized to play a key role in cardiovascular aging; however, data on antioxidant and redox regulating systems in the aging heart are controversial. The aim of the present study was to examine the effect of aging on critical antioxidant enzymes and two major redox-regulatory systems glutathione (GSH) and thioredoxin (Trx) system in hearts from adult (6-month-old), old (15-month-old), and senescent (26-monthold) rats. Aging was associated with a non-uniform array of changes, including decline in contents of reduced GSH and total mercaptans in the senescent heart. The activities of Mn-superoxide dismutase (SOD2), glutathione peroxidase (GPx), glutathione reductase (GR), and thioredoxin reductase (TrxR) exhibited an age-related decline, whereas catalase was unchanged and Cu,Zn-superoxide dismutase (SOD1) displayed only slight decrease in old heart and was unchanged in the senescent heart. GR, Trx, and peroxiredoxin levels were significantly reduced in old and/or senescent hearts, indicating a diminished expression of these proteins. In contrast, SOD2 level was unchanged in the old heart and was slightly elevated in the senescent heart. Decline in GPx activity was accompanied by a loss of GPx level only in old rats, the level in senescent heart was unchanged. These results indicate age-related posttranslational protein modification of SOD2 and GPx. In summary, our data suggest that changes are more pronounced in senescent than in old rat hearts and support the view that aging is associated with disturbed redox balance that could alter cellular signaling and regulation. [ABSTRACT FROM AUTHOR]

Daucosterol (DS) is a plant phytosterol which is shown to induce oxidative stress mediated apoptosis in various cancer cell lines. However, the molecular mechanism underlying its cellular action has not been documented against Non- Small Cell Lung Cancer (NSCLC). Therefore, we attempted to decipher the mechanisms responsible for DS-induced anti-proliferation on human NSCLC cells. The present study showed, DS strongly inhibits the growth of A549 cells after 72 h time point with an IC 50 value of ∼20.9 μM. Further DS elicits increased reactive oxygen species level and promote intrinsic apoptotic cell death on A549 cells as evidenced by increased expression of caspase-3, caspase-9, Bax, PARP inactivation, cytochrome-c release, and diminished expression of bcl-2 protein. DS failed to display its apoptotic actions upon pretreatment with the reactive oxygen species inhibitor NAC (N-acetyl cysteine). Indeed, apoptotic signal which was enhanced through p53/p21 activation and knockdown of p53 expression also moderately affected the DS induced apoptosis. In addition, DS preferentially inhibited the cell growth of p53 wild-type NSCLC cell lines than the mutant p53 models. Further, we show that inhibition of Thioredoxin (TrxR) redox system is principally associated with DS induced oxidative stress mediated apoptotic cell death on A549 cells. Moreover, we also demonstrated that DS stably interacted with serine residues in TrxR active sites. The obtained results confirmed that the anti-proliferative mechanism and increased reactive oxygen species level of DS was associated with down-regulation of TrxR1 pathway which triggers the p53 mediated intrinsic apoptotic mode of cell death in NSCLC cells. Image 1 [ABSTRACT FROM AUTHOR]

Abstract: Thioredoxin redox system has been implicated as an intracellular anti-oxidant defense system leading to reduction of cellular oxidative stresses utilizing electrons from NADPH. From high content screening of small molecules targeting the system, gliotoxin, a fungal metabolite, was identified as an active compound. Gliotoxin potently accelerates NADPH oxidation and reduces H2O2. The compound reduces H2O2 to H2O by replacing the function of peroxiredoxin in vitro and decreases intracellular level of H2O2 in HeLa cells. The anti-oxidant activity of gliotoxin was further validated H2O2-mediated cellular phenotype of angiogenesis. The proliferation of endothelial cells was inhibited by the compound at nanomolar range. In addition, H2O2-induced tube formation and invasion of the cells were blocked by gliotoxin. Together, these results demonstrate that gliotoxin is a new small molecule targeting thioredoxin redox system. [Copyright &y& Elsevier]