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Dynamic modeling of Nrf2 pathway activation in liver cells after toxicant exposure.

ABSTRACT: Cells are exposed to oxidative stress and reactive metabolites every day. The Nrf2 signaling pathway responds to oxidative stress by upregulation of antioxidants like glutathione (GSH) to compensate the stress insult and re-establish homeostasis. Although mechanisms describing the interaction between the key pathway constituents Nrf2, Keap1 and p62 are widely reviewed and discussed in literature, quantitative dynamic models bringing together these mechanisms with time-resolved data are limited. Here, we present an ordinary differential equation (ODE) based dynamic model to describe the dynamic response of Nrf2, Keap1, Srxn1 and GSH to oxidative stress caused by the soft-electrophile diethyl maleate (DEM). The time-resolved data obtained by single-cell confocal microscopy of green fluorescent protein (GFP) reporters and qPCR of the Nrf2 pathway components complemented with siRNA knock down experiments, is accurately described by the calibrated mathematical model. We show that the quantitative model can describe the activation of the Nrf2 pathway by compounds with a different mechanism of activation, including drugs which are known for their ability to cause drug induced liver-injury (DILI) i.e., diclofenac (DCF) and omeprazole (OMZ). Finally, we show that our model can reveal differences in the processes leading to altered activation dynamics amongst DILI inducing drugs.

SUBMITTER: Hiemstra S

PROVIDER: S-EPMC9072554 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Dynamic modeling of Nrf2 pathway activation in liver cells after toxicant exposure.

Hiemstra Steven S Fehling-Kaschek Mirjam M Kuijper Isoude A IA Bischoff Luc J M LJM Wijaya Lukas S LS Rosenblatt Marcus M Esselink Jeroen J van Egmond Allard A Mos Jornt J Beltman Joost B JB Timmer Jens J van de Water Bob B Kaschek Daniel D

Scientific reports 20220505 1

Cells are exposed to oxidative stress and reactive metabolites every day. The Nrf2 signaling pathway responds to oxidative stress by upregulation of antioxidants like glutathione (GSH) to compensate the stress insult and re-establish homeostasis. Although mechanisms describing the interaction between the key pathway constituents Nrf2, Keap1 and p62 are widely reviewed and discussed in literature, quantitative dynamic models bringing together these mechanisms with time-resolved data are limited. ...[more]

PMID: 35513409

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Project description:ImportanceRecognizing associations between exposure to common environmental toxicants and mental disorders such as depression is crucial for guiding targeted mechanism research and the initiation of disease prevention efforts.ObjectivesTo comprehensively screen and assess the associations between potential environmental toxicants and depressive symptoms and to assess whether systemic inflammation serves as a mediator.Design, setting, and participantsA total of 3427 participants from the 2013-2014 and 2015-2016 waves of the National Health and Nutrition Examination and Survey who had information on blood or urine concentrations of environmental toxicants and depression scores assessed by the 9-item Patient Health Questionnaire (PHQ-9) were included. Statistical analysis was performed from July 1, 2023, to January 31, 2024.ExposuresSixty-two toxicants in 10 categories included acrylamide, arsenic, ethylene oxide, formaldehyde, iodine, metals, nicotine metabolites, polycyclic aromatic hydrocarbons, volatile organic compound (VOC) metabolites; and perchlorate, nitrate, and thiocyanate.Main outcomes and measuresAn exposome-wide association study and the deletion-substitution-addition algorithm were used to assess associations with depression scores (PHQ-9 ≥5) adjusted for other important covariates. A mediation analysis framework was used to evaluate the mediating role of systemic inflammation assessed by the peripheral white blood cell count.ResultsAmong the 3427 adults included, 1735 (50.6%) were women, 2683 (78.3%) were younger than 65 years, and 744 (21.7%) were 65 years or older, with 839 (24.5%) having depressive symptoms. In terms of race and ethnicity, 570 participants (16.6%) were Mexican American, 679 (19.8%) were non-Hispanic Black, and 1314 (38.3%) were non-Hispanic White. We identified associations between 27 chemical compounds or metals in 6 of 10 categories of environmental toxicants and the prevalence of depressive symptoms, including the VOC metabolites N-acetyl-S-(2-hydroxy-3-butenyl)-l-cysteine (odds ratio [OR], 1.74 [95% CI, 1.38, 2.18]) and total nicotine equivalent-2 (OR, 1.42 [95% CI, 1.26-1.59]). Men and younger individuals appear more vulnerable to environmental toxicants than women and older individuals. Peripheral white blood cell count mediated 5% to 19% of the associations.Conclusions and relevanceIn this representative cross-sectional study of adults with environmental toxicant exposures, 6 categories of environmental toxicants were associated with depressive symptoms with mediation by systemic inflammation. This research provides insight into selecting environmental targets for mechanistic research into the causes of depression and facilitating efforts to reduce environmental exposures.

Project description:BackgroundHypoxia training enhances the endurance capacity of athletes. This response may in part be attributed to the hypoxia-induced increase in antioxidant capacity in skeletal muscles. Nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor which regulates the expression of genes via binding to the antioxidant-response element (ARE) of these genes, plays a crucial role in stimulating the body's defense system and potentially responds to hypoxia. Meanwhile, hypoxia-inducible factor-1α (HIF-1α) is an important player in protecting cells from hypoxic stress. The purpose of this study was to investigate the effects of acute hypoxia exposure with different durations on the activation of Nrf2-ARE pathway and a possible regulatory role of HIF-1α in these responses.MethodsC57BL/6J mice were allocated into the non-hypoxia 0-hour, 6-hour, 24-hour, and 48-hour hypoxic exposure (11.2% oxygen) groups. The quadriceps femoris was collected immediately after hypoxia. Further, to investigate the possible role of HIF-1α, C2C12 myoblasts with HIF-1α knockdown by small interfering RNA (siRNA) and the inducible HIF-1α transgenic mice were employed.ResultsThe results showed that 48-hour hypoxia exposure up-regulated protein expression of Nrf2, Nrf2/ARE binding activity and the transcription of antioxidative genes containing ARE (Sod1 and others) in mouse skeletal muscle. Moreover, HIF-1α siRNA group of C2C12 myoblasts showed a remarkable inhibition of Nrf2 protein expression and nuclear accumulation in hypoxia exposure for 72 hours compared with that in siRNA-Control group of the cells. In addition, HIF-1α transgenic mice gave higher Nrf2 protein expression, Nrf2/ARE binding activity and expressions of Nrf2-mediated antioxidative genes in their skeletal muscle, compared with those in the wild-type mice.ConclusionsThe findings suggested that the acute hypoxia exposure could trigger the activation of Nrf2-ARE pathway, with longer duration associated with higher responses, and HIF-1α expression might be involved in promoting the Nrf2-mediated antioxidant responses in skeletal muscle.

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Dynamic modeling of Nrf2 pathway activation in liver cells after toxicant exposure.

Publications

Dynamic modeling of Nrf2 pathway activation in liver cells after toxicant exposure.

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