Exploration of a system for cellular response to the electrophiles exhibiting skin sensitization potential

科学研究費助成事業(学術研究助成基金助成金)研究成果報告書：挑戦的萌芽研究2011-2012課題番号：2365906

The Role of the Keap1/Nrf2 Pathway in the Cellular Response to Methylmercury

Methylmercury (MeHg) is an environmental electrophile that covalently modifies cellular proteins with reactive thiols, resulting in the formation of protein adducts. While such protein modifications, referred to as S-mercuration, are thought to be associated with the enzyme dysfunction and cellular damage caused by MeHg exposure, the current consensus is that (1) there is a cellular response to MeHg through the activation of NF-E2-related factor 2 (Nrf2) coupled to S-mercuration of its negative regulator, Kelch-like ECH-associated protein 1 (Keap1), and (2) the Keap1/Nrf2 pathway protects against MeHg toxicity. In this review, we introduce our findings and discuss the observations of other workers concerning the S-mercuration of cellular proteins by MeHg and the importance of the Keap1/Nrf2 pathway in protection against MeHg toxicity in cultured cells and mice

環境中親電子物質によるシグナル伝達変動とその制御に関する包括的研究

科学研究費助成事業 研究成果報告書：基盤研究(S)2013-2017課題番号 : 2522010

中国の慢性砒素汚染地域での介入研究 : 生体内NO産生変動と中毒症状軽減との関係

科学研究費助成事業（科学研究費補助金）研究成果報告書：基盤研究(B)（1） 平成13～14年度課題番号：16576029原本の末尾には原著論文・学会発表論文等が掲載されていますが、著作権保護のため、つくばリポジトリでの公開はいたしません

大気中ナノ粒子に含有され酸化ストレスを惹起するキノン化合物の生体影響評価

科学研究費助成事業（科学研究費補助金）研究成果報告書：基盤研究(B)（一般） 平成15～17年度課題番号：15390184原本の末尾には原著論文・学会発表論文等が掲載されていますが、著作権保護のため、つくばリポジトリでの公開はいたしません

TRPC6 counteracts TRPC3-Nox2 protein complex leading to attenuation of hyperglycemia-induced heart failure in mice

Excess production of reactive oxygen species (ROS) caused by hyperglycemia is a major risk factor for heart failure. We previously reported that transient receptor potential canonical 3 (TRPC3) channel mediates pressure overload-induced maladaptive cardiac fibrosis by forming stably functional complex with NADPH oxidase 2 (Nox2). Although TRPC3 has been long suggested to form hetero-multimer channels with TRPC6 and function as diacylglycerol-activated cation channels coordinately, the role of TRPC6 in heart is still obscure. We here demonstrated that deletion of TRPC6 had no impact on pressure overload-induced heart failure despite inhibiting interstitial fibrosis in mice. TRPC6-deficient mouse hearts 1 week after transverse aortic constriction showed comparable increases in fibrotic gene expressions and ROS production but promoted inductions of inflammatory cytokines, compared to wild type hearts. Treatment of TRPC6-deficient mice with streptozotocin caused severe reduction of cardiac contractility with enhancing urinary and cardiac lipid peroxide levels, compared to wild type and TRPC3-deficient mice. Knockdown of TRPC6, but not TRPC3, enhanced basal expression levels of cytokines in rat cardiomyocytes. TRPC6 could interact with Nox2, but the abundance of TRPC6 was inversely correlated with that of Nox2. These results strongly suggest that Nox2 destabilization through disrupting TRPC3-Nox2 complex underlies attenuation of hyperglycemia-induced heart failure by TRPC6.Fil: Oda, Sayaka. Okazaki Institute for Integrative Bioscience; Japón. SOKENDAI; JapónFil: Numaga Tomita, Takuro. Okazaki Institute for Integrative Bioscience; Japón. SOKENDAI; JapónFil: Kitajima, Naoyuki. Okazaki Institute for Integrative Bioscience; Japón. Kyushu University; JapónFil: Tomizaki, Takashi. Okazaki Institute for Integrative Bioscience; Japón. Kyushu University; Japón. University of Tsukuba; JapónFil: Harada, Eri. Ajinomoto Co.; Japón. EA Pharma Co.; JapónFil: Shimauchi, Tsukasa. Okazaki Institute for Integrative Bioscience; Japón. Kyushu University; JapónFil: Nishimura, Akiyuki. Okazaki Institute for Integrative Bioscience; Japón. SOKENDAI; Japón. Ajinomoto Co.; JapónFil: Ishikawa, Tatsuya. Kyushu University; Japón. Ajinomoto Co.; Japón. EA Pharma Co.; JapónFil: Kumagai, Yoshito. University of Tsukuba; JapónFil: Birnbaumer, Lutz. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Nishida, Motohiro. Okazaki Institute for Integrative Bioscience; Japón. SOKENDAI; Japón. Kyushu University; Japón. PRESTO; Japó

Methylmercury promotes prostacyclin release from cultured human brain microvascular endothelial cells via induction of cyclooxygenase-2 through activation of the EGFR-p38 MAPK pathway by inhibiting protein tyrosine phosphatase 1B activity

Methylmercury is an environmental pollutant that exhibits neurotoxicity when ingested, primarily in the form of neuropathological lesions that localize along deep sulci and fissures, in addition to edematous and inflammatory changes in patient cerebrums. These conditions been known to give rise to a variety of ailments that have come to be collectively termed Minamata disease. Since prostaglandins I2 and E2 (PGI2 and PGE2) increase vascular permeability and contribute to the progression of inflammatory changes, we hypothesize that methylmercury induces the synthesis of these prostaglandins in brain microvascular endothelial cells and pericytes. To test this theory, human brain microvascular endothelial cells and pericytes were cultured and treated with methylmercury, after which the PGI2 and PGE2 released from endothelial cells and/or pericytes were quantified by enzyme-linked immunosorbent assay while protein and mRNA expressions in endothelial cells were analyzed by western blot analysis and real-time reverse transcription polymerase chain reaction, respectively. Experimental results indicate that methylmercury inhibits the activity of protein tyrosine phosphatase 1B, which in turn activates the epidermal growth factor receptor–p38 mitogen-activated protein kinase pathway that induces cyclooxygenase-2 expression. It was also found that the cyclic adenosine 3′,5′-monophosphate pathway, which can be activated by PGI2 and PGE2, is involved in methylmercury-induced cyclooxygenase-2 expression. Since it appears that protein tyrosine phosphatase 1 B serves as a sensor protein for methylmercury in these mechanisms, it is our belief that the results of the present study may provide additional insights into the molecular mechanisms responsible for edematous and inflammatory changes in the cerebrum of patients with Minamata disease

Adaptive Responses to Electrophilic Stress and Reactive Sulfur Species as their Regulator Molecules

We are exposed to numerous xenobiotic electrophiles on a daily basis through the environment, lifestyle, and dietary habits. Although such reactive species have been associated with detrimental effects, recent accumulated evidence indicates that xenobiotic electrophiles appear to act as signaling molecules. In this review, we introduce our findings on 1) activation of various redox signaling pathways involved in cell proliferation, detoxification/excretion of electrophiles, quality control of cellular proteins, and cell survival during exposure to xenobiotic electrophiles at low concentrations through covalent modification of thiol groups in sensor proteins, and 2) negative regulation of reactive sulfur species (RSS) in the modulation of redox signaling and toxicity caused by xenobiotic electrophiles

Spatiotemporal analysis of the UPR transition induced by methylmercury in the mouse brain

Methylmercury (MeHg), an environmental toxicant, induces neuronal cell death and injures a specific area of the brain. MeHg-mediated neurotoxicity is believed to be caused by oxidative stress and endoplasmic reticulum (ER) stress but the mechanism by which those stresses lead to neuronal loss is unclear. Here, by utilizing the ER stress-activated indicator (ERAI) system, we investigated the signaling alterations in the unfolded protein response (UPR) prior to neuronal apoptosis in the mouse brain. In ERAI transgenic mice exposed to MeHg (25 mg/kg, S.C.), the ERAI signal, which indicates activation of the cytoprotective pathway of the UPR, was detected in the brain. Interestingly, detailed ex vivo analysis showed that the ERAI signal was localized predominantly in neurons. Time course analysis of MeHg exposure (30 ppm in drinking water) showed that whereas the ERAI signal was gradually attenuated at the late phase after increasing at the early phase, activation of the apoptotic pathway of the UPR was enhanced in proportion to the exposure time. These results suggest that MeHg induces not only ER stress but also neuronal cell death via a UPR shift. UPR modulation could be a therapeutic target for treating neuropathy caused by electrophiles similar to MeHg