title: Estrogen-induced mitochondrial reactive oxygen species as signal-transducing messengers.
abstract: We report here evidence in support of the role of 17beta-estradiol- (E2-) induced mitochondrial (mt) reactive oxygen species (ROS) as signal-transducing messengers. On the basis of monitoring the oxidation of 2',7'-dichlorofluorescin by spectrofluorometry, flow cytometry, and confocal microscopy, we have identified that exposure of E2 triggers the immediate rapid production of intracellular ROS ranging from a 1- to severalfold increase in a variety of cells. E2-stimulated ROS production does not correlate with the activity of the estrogen receptor (ER) in the cells. The ROS is most likely hydrogen peroxide based on its inhibition by antioxidants and catalase and lack of any effects of E2 on O(2)(*)(-) or NO(*) formation. Confocal microscopy showed that ROS is localized in the perinuclear mitochondria. E2 through anchorage- and integrin-dependent signaling to mitochondria increased ROS generation. Increased intracellular ROS formation identified here for the first time may explain the mechanism of previously reported oxidative damage and subsequent genetic alterations including mutations produced by elevated concentrations of estrogens. The functional consequences of E2-induced ROS formation included the enhanced cell motility as shown by the increase in cdc42 and activation of Pyk2 and the increased phosphorylation of signaling proteins c-jun and CREB. E2-induced ROS activated the binding of three oxidant-sensitive transcription factors: AP-1, CREB, and nuclear respiratory factor 1. In addition to ERs as signaling molecules, our findings further revealed that E2-induced mt ROS also act as signal transducing messengers and suggest new targets for the development of antioxidant-based drugs or antioxidant gene therapy for the prevention and treatment of estrogen-dependent cancer.
authors.affiliation: Department of Environmental Health Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Felty
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Xiong
authors.forename: Dongmei
authors.initials: D
authors.lastname: Sun
authors.forename: Shubhashish
authors.initials: S
authors.lastname: Sarkar
authors.forename: Kamaleshwar P
authors.initials: KP
authors.lastname: Singh
authors.forename: Jai
authors.initials: J
authors.lastname: Parkash
authors.forename: Deodutta
authors.initials: D
authors.lastname: Roy
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000502:physiology*; D045744:Cell Line, Tumor; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004958:Estradiol / Q000737:chemistry*; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000737:chemistry / Q000502:physiology*; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; D016877:Oxidants / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000494:pharmacology; D015290:Second Messenger Systems / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; C495633:NRF1 protein, human; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; D016877:Oxidants; D016755:Proto-Oncogene Proteins c-jun; D017382:Reactive Oxygen Species; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D004958:Estradiol