title: Estradiol reduces ferrous citrate complex-induced NOS2 up-regulation in cerebral endothelial cells by interfering the nuclear factor kappa B transactivation through an estrogen receptor β-mediated pathway.
abstract: Hemorrhagic stroke caused leakage of red blood cells which converts to hemoglobin, heme, and iron accumulated at the lesions. High concentration of ferrous iron from subarachnoid hemorrhage (SAH) induced cerebral vasospasm. Using the two-hemorrhage SAH model in rats, we previously demonstrated that estradiol (E2) significantly attenuated the SAH-induced vasospasm by inhibiting the NOS2 expression. Adding ferrous citrate (FC) complexes to the primary cultured mouse cerebral endothelial cells (CEC) to mimic the SAH conditions, we also showed that FC up-regulates NOS2 through nuclear translocation of NFκB induced by free radicals generation. Here, we further studied the molecular mechanism underlying E2-mediated reduction of the FC-induced up-regulation of NOS2. Treatment with E2 (100 nM) reduced the FC (100 µM)-induced increases of free radical generation and the levels of NOS2 mRNA and protein in the CEC. Moreover, E2 also prevented the FC-induced increases of IκBα phosphorylation, NFκB nuclear translocation, NFκB binding onto the NOS2 promoter, and the NOS2 promoter luciferase activity. However, knock-down the estrogen receptor β (ERβ), but not ERα, abolished the E2-mediated prevention on the FC-induced increases of NOS2 mRNA and protein. The data from the present study suggest that E2 inhibited NOS2 gene expression by interfering with NFκB nuclear translocation and NFκB binding onto the NOS2 through an ERβ-mediated pathway. Our results provide the molecular basis for designing the applicable therapeutic or preventive strategies in the treatment SAH patients.
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan ; Department of Physiology, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wen-Sen
authors.initials: WS
authors.lastname: Lee
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000166:cytology*; D047369:Chromatin Immunoprecipitation; D019343:Citric Acid; D017931:DNA Primers / Q000235:genetics; D042783:Endothelial Cells / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology*; D047629:Estrogen Receptor beta / Q000378:metabolism; D005296:Ferrous Compounds / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D008156:Luciferases; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation / Q000187:drug effects*
chemical_list: D017931:DNA Primers; D047629:Estrogen Receptor beta; D005296:Ferrous Compounds; D016328:NF-kappa B; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D019343:Citric Acid; C016600:ferrous citrate; D004958:Estradiol; D008156:Luciferases; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse