title: Reactive oxygen species regulate ceruloplasmin by a novel mRNA decay mechanism involving its 3'-untranslated region: implications in neurodegenerative diseases.
abstract: Ceruloplasmin (Cp), a copper-containing protein, plays a significant role in body iron homeostasis as aceruloplasminemia patients and Cp knock-out mice exhibit iron overload in several tissues including liver and brain. Several other functions as oxidant, as antioxidant, and in nitric oxide metabolism are also attributed to Cp. Despite its role in iron oxidation and other biological oxidation reactions the regulation of Cp by reactive oxygen species (ROS) remains unexplored. Cp is synthesized in liver as a secretory protein and predominantly as a glycosylphosphatidylinositol-anchored membrane-bound form in astroglia. In this study we demonstrated that Cp expression is decreased by an mRNA decay mechanism in response to extracellular (H2O2) or intracellular oxidative stress (by mitochondrial chain blockers rotenone or antimycin A) in both hepatic and astroglial cells. The promotion of Cp mRNA decay is conferred by its 3'-untranslated region (UTR). When chloramphenicol acetyltransferase (CAT) gene was transfected as a chimera with Cp 3'-UTR in hepatic or astroglial cells, in response to either H2O2, rotenone, or antimycin A, the expression of CAT transcript was decreased, whereas expression of a 3'-UTR-less CAT transcript remained unaffected. RNA gel shift assay showed significant reduction in 3'-UTR-binding protein complex by ROS in both cell types that was reversed by the antioxidant N-acetylcysteine suggesting that ROS affects RNA-protein complex formation to promote Cp mRNA decay. Our finding is not only the first demonstration of regulation of Cp by ROS by a novel post-transcriptional mechanism but also provides a mechanism of iron deposition in neurodegenerative diseases.
authors.affiliation: Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110 067, India.
authors.forename: Nisha
authors.initials: N
authors.lastname: Tapryal
authors.forename: Chaitali
authors.initials: C
authors.lastname: Mukhopadhyay
authors.forename: Dola
authors.initials: D
authors.lastname: Das
authors.forename: Paul L
authors.initials: PL
authors.lastname: Fox
authors.forename: Chinmay K
authors.initials: CK
authors.lastname: Mukhopadhyay
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics / Q000378:metabolism*; D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D000968:Antimycin A / Q000494:pharmacology; D045744:Cell Line, Tumor; D002570:Ceruloplasmin / Q000096:biosynthesis* / Q000235:genetics; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D019190:Iron Overload / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D019636:Neurodegenerative Diseases / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D020871:RNA Stability / Q000187:drug effects*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D020413:3' Untranslated Regions; D000935:Antifungal Agents; D016166:Free Radical Scavengers; D016877:Oxidants; D016601:RNA-Binding Proteins; D014475:Uncoupling Agents; D012402:Rotenone; D000968:Antimycin A; D006861:Hydrogen Peroxide; D002570:Ceruloplasmin; D000111:Acetylcysteine