Dynamics of Nrf2 and Keap1 in ARE-Mediated NQO1 Expression by Wasabi 6-(Methylsulfinyl)hexyl Isothiocyanate

Abstract

6-(Methylsulfinyl)hexyl isothiocyanate (6-MSITC) is a bioactive ingredient present in wasabi, a popular pungent spice in Japan. Previous studies have revealed the cytoprotective and cancer chemopreventive effects of 6-MSITC. This study aims to clarify the molecular mechanisms by investigating the action of 6-MSITC on the Nrf2/Keap1 system. 6-MSITC up-regulated the expression of NAD(P)H:quinone oxidoreductase 1 (NQO1) by increasing the Nrf2 level. Treatment with 6-MSITC extended the half-life (t(1/2)) of Nrf2 protein from 11.5 to 35.2 min, approximately three times longer. Moreover, 6-MSITC suppressed the ubiquitination of Nrf2 but not Keap1. Alternatively, a modified Keap1 was observed in 6-MSITC-treated cells accompanying reduction of normal Keap1 protein. The results from cellular fractionation and immunocytochemistry assay revealed that Nrf2 was primarily accumulated in nucleus. EMSA and the reporter gene assay further demonstrated that 6-MSITC augmented Nrf2-ARE binding and transcription activity. Silencing Nrf2 using Nrf2 siRNA markedly reduced the Nrf2 level and ARE-driven activity under both baseline and 6-MSITC-induced conditions. Our data revealed that 6-MSITC enhanced Nrf2/ARE-driven NQO1 expression by stabilizing Nrf2 that was accomplished by modifying Keap1 with consequent inhibition of the ubiquitination and proteasomal turnover of Nrf2. The findings provide an insight into the mechanisms underlying 6-MSITC in cytoprotection and cancer chemoprevention.

Atorvastatin has a protective effect in a mouse model of bronchial asthma through regulating tissue transglutaminase and triggering receptor expressed on myeloid cells-1 expression

“…When a cell is subjected to oxidative stress, Nrf2 interacts with kelch-like ECH-associated protein 1 to perform uncoupling prior to being activated and transported into the cell nucleus. Nrf2 then binds to antioxidant response elements in gene promoters to regulate the expression of the downstream antioxidant enzyme NQO1, thus enhancing the tolerance of cells to oxidative stress (45,46). The pathogenesis of asthma is known to involve ROS generation and loss of antioxidant defenses (43).…”

“…The pathogenesis of asthma is known to involve ROS generation and loss of antioxidant defenses (43). A widely recognized central feature of asthma and other airway inflammatory diseases are alterations in alveolar and lung GSH metabolism (45). In the present study, atorvastatin increased the expression of Nrf2, NQO1 and antioxidant enzyme GSH, reduced the expression of ROS and improved bronchial remodeling in a mouse model.…”

Neuroprotection by 6-(methylsulfinyl)hexyl isothiocyanate in a 6-hydroxydopamine mouse model of Parkinson׳s disease

“…Our results are supported by Mizuno et al (2011), who have shown that 6-MSITC prevents oxidative stress-induced cytotoxicity in rat striatal cultures by raising the intracellular GSH content via an increase in γ-glutamylcysteine synthetase expression, induced by the activation of the Nrf2-ARE detoxification pathway. In this context, recent studies suggest that the cytoprotective effects of 6-MSITC could be ascribed to its ability to modulate the Nrf2-ARE pathway by stabilizing Nrf2 at nuclear level, probably by enhancing Keap1 modification and decreasing Nrf2 degradation (Korenori et al, 2013;Hou et al, 2011).…”

The Protective Role of Resveratrol against Arsenic Trioxide-Induced Cardiotoxicity

“…Glutathione redox state correlates with the biological status of the cell [24]. On the other hand, Nrf2 has been demonstrated to be a critical transcription factor that binds to the antioxidant response element in the promoter region of a number of genes, encoding for phase I and phase II antioxidative enzymes and cytoprotective proteins, such as NAD(P)H:quinone acceptor oxidoreductase 1, glutathione S-transferases, the glutamyl cysteine ligase catalytic subunit, and multidrug resistance-associated protein [25]. Hence, Nrf2 pathway is presumably the most important pathway in cells to deal with oxidative stress generated from exposure to exogenous and endogenous chemicals [20].…”