Protection against Chromium (VI)-induced oxidative stress and apoptosis by Nrf2. Recruiting Nrf2 into the nucleus and disrupting the nuclear Nrf2/Keap1 association by toxic metal.
He-XQ; Lin-GX; Chen-MG; Ma-Q
FASEB J 2007 Apr; 21(6)(Suppl):A1181
Chromium(VI) (Cr) is a major environmental toxic metal and human carcinogen. The molecular events mediating cellular responses to Cr(VI) are not clear at present. We show that Cr(VI) potently induced apoptosis and production of reactive oxygen species (ROS) in a concentration-dependent manner. Mouse embryonic fibroblast cells lacking Nrf2 exhibited elevated ROS production and apoptosis, which were markedly further increased by Cr(VI). Protection by Nrf2 correlated with induction of cytoprotective genes Ho-1 and Nqo1. Induction of the genes by Cr(VI) involved inhibition of ubiquitination of Nrf2 and accumulation of Nrf2 into the nucleus. In the nucleus, treatment with Cr(VI), but not phenolic antioxidant tBHQ, librates Nrf2 from Nrf2/Keap1 association and recruits Nrf2 to the antioxidant response elements (ARE) located in the enhancers of Ho-1 and Nqo1. Activation of Nrf2 by Cr(VI) was accompanied by the nuclear translocation and deubiquitination of Keap1 implicating recycling of Keap1 in Nrf2 signaling. Thus, protection against Cr(VI) toxicity involves a transcriptional signaling loop that includes activation of Nrf2 signaling by toxic metal, transcription of ARE-driven genes, and reduction of ROS production.
Cellular-function; Cellular-structures; Cell-differentiation; Cell-function; Cell-biology; Cancer; Chemical-analysis; Biochemical-analysis; Leukocytes; Blood-disorders; Blood-analysis; Genes; Genetic-disorders; Metal-compounds; Animal-studies
Health Effects Laboratory Division, CDC National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV, 26505
Abstract; Conference/Symposia Proceedings
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