The Experts below are selected from a list of 1410 Experts worldwide ranked by ideXlab platform
Tracey A Rouault - One of the best experts on this subject based on the ideXlab platform.
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absence of Iron Responsive Element binding protein 2 causes a novel neurodegenerative syndrome
Brain, 2019Co-Authors: Gregory Costain, Tracey A Rouault, Manik C. Ghosh, Nunziata Maio, Amanda Carnevale, Grace YoonAbstract:Disruption of cellular Iron homeostasis can contribute to neurodegeneration. In mammals, two Iron-regulatory proteins (IRPs) shape the expression of the Iron metabolism proteome. Targeted deletion of Ireb2 in a mouse model causes profoundly disordered Iron metabolism, leading to functional Iron deficiency, anemia, erythropoietic protoporphyria, and a neurodegenerative movement disorder. Using exome sequencing, we identified the first human with bi-allelic loss-of-function variants in the gene IREB2 leading to an absence of IRP2. This 16-year-old male had neurological and haematological features that emulate those of Ireb2 knockout mice, including neurodegeneration and a treatment-resistant choreoathetoid movement disorder. Cellular phenotyping at the RNA and protein level was performed using patient and control lymphoblastoid cell lines, and established experimental assays. Our studies revealed functional Iron deficiency, altered post-transcriptional regulation of Iron metabolism genes, and mitochondrial dysfunction, as observed in the mouse model. The patient's cellular abnormalities were reversed by lentiviral-mediated restoration of IRP2 expression. These results confirm that IRP2 is essential for regulation of Iron metabolism in humans, and reveal a previously unrecognized subclass of neurodegenerative disease. Greater understanding of how the IRPs mediate cellular Iron distribution may ultimately provide new insights into common and rare neurodegenerative processes, and could result in novel therapies.
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A Ferroportin Transcript that Lacks an Iron-Responsive Element Enables Duodenal and Erythroid Precursor Cells to Evade Translational Repression
Cell metabolism, 2009Co-Authors: De-liang Zhang, Robert M. Hughes, Hayden Ollivierre-wilson, Manik C. Ghosh, Tracey A RouaultAbstract:Ferroportin (FPN1), the sole characterized mammalian Iron exporter, has an Iron-Responsive Element (IRE) in its 5' untranslated region, which ensures that its translation is repressed by Iron regulatory proteins (IRPs) in Iron-deficient conditions to maintain cellular Iron content. However, here we demonstrate that duodenal epithelial and erythroid precursor cells utilize an alternative upstream promoter to express a FPN1 transcript, FPN1B, which lacks the IRE and is not repressed in Iron-deficient conditions. The FPN1B transcript encodes ferroportin with an identical open reading frame and contributes significantly to ferroportin protein expression in erythroid precursors and likely also in the duodenum of Iron-starved animals. The identification of FPN1B reveals how FPN1 expression can bypass IRP-dependent repression in intestinal Iron uptake, even when cells throughout the body are Iron deficient. In erythroid precursor cells, we hypothesize that FPN1B expression enhances real-time sensing of systemic Iron status and facilitates restriction of erythropoiesis in response to low systemic Iron.
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clinical severity and thermodynamic effects of Iron Responsive Element mutations in hereditary hyperferritinemia cataract syndrome
Journal of Biological Chemistry, 1999Co-Authors: Charles R Allerson, Mario Cazzola, Tracey A RouaultAbstract:Abstract Hereditary hyperferritinemia-cataract syndrome (HHCS) is a novel genetic disorder characterized by elevated serum ferritin and early onset cataract formation. The excessive ferritin production in HHCS patients arises from aberrant regulation of l-ferritin translation caused by mutations within the Iron-Responsive Element (IRE) of thel-ferritin transcript. IREs serve as binding sites for Iron regulatory proteins (IRPs), Iron-sensing proteins that regulate ferritin translation. Previous observations suggested that each unique HHCS mutation conferred a characteristic degree of hyperferritinemia and cataract severity in affected individuals. Here we have measured the in vitro affinity of the IRPs for the mutant IREs and correlated decreases in binding affinity with clinical severity. Thermodynamic analysis of these IREs has also revealed that although some HHCS mutations lead to changes in the stability and secondary structure of the IRE, others appear to disrupt IRP-IRE recognition with minimal effect on IRE stability. HHCS is a noteworthy example of a human genetic disorder that arises from mutations within a protein-binding site of an mRNA cis-acting Element. Analysis of the effects of these mutations on the energetics of the RNA-protein interaction explains the phenotypic variabilities of the disease state.
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structure and dynamics of the Iron Responsive Element rna implications for binding of the rna by Iron regulatory binding proteins
Journal of Molecular Biology, 1997Co-Authors: Kenneth J Addess, Tracey A Rouault, Richard D. Klausner, James P Basilion, Arthur PardiAbstract:The Iron Responsive Element (IRE) is a ∼30 nucleotide RNA hairpin that is located in the 5′ untranslated region of all ferritin mRNAs and in the 3′ untranslated region of all transferrin receptor mRNAs. The IREs are bound by two related IRE-binding proteins (IRPs) which help control intracellular levels of Iron by regulating the expression of both ferritin and transferrin receptor genes. Multi-dimensional NMR and computational approaches were used to study the structure and dynamics of the IRE RNA in solution. The NMR data are consistent with formation of A-form helical stem regions, a one-base internal bulge and a Watson-Crick C·G base-pair between the first and fifth nucleotides in the loop. A superposition of refined structures indicates that the conserved C in the internal bulge, and three residues in the six-nucleotide hairpin loop are quite dynamic in this RNA. The structural roles of the stems, the loop and the bulge in the function of the IRE RNA and in possible interactions with the Iron regulatory protein are discussed.
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the Iron Responsive Element binding protein a target for synaptic actions of nitric oxide
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Samie R Jaffrey, Tracey A Rouault, Richard D. Klausner, Noam A Cohen, Solomon H SnyderAbstract:Abstract Molecular targets for the actions of nitric oxide (NO) have only been partially clarified. The dynamic properties of the Iron-sulfur (Fe-S) cluster of the Iron Responsive-Element binding protein (IRE-BP) suggested that it might serve as a target for NO produced in response to glutamatergic stimulation in neurons. In the present study, we demonstrate that N-methyl-D-aspartate, acting through NO, stimulates the RNA-binding function of the IRE-BP in brain slices while diminishing its aconitase activity. In addition, we demonstrate a selective localization of the IRE-BP in discrete neuronal structures, suggesting a potential role for this protein in the response of neurons to NO.
Richard D. Klausner - One of the best experts on this subject based on the ideXlab platform.
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structure and dynamics of the Iron Responsive Element rna implications for binding of the rna by Iron regulatory binding proteins
Journal of Molecular Biology, 1997Co-Authors: Kenneth J Addess, Tracey A Rouault, Richard D. Klausner, James P Basilion, Arthur PardiAbstract:The Iron Responsive Element (IRE) is a ∼30 nucleotide RNA hairpin that is located in the 5′ untranslated region of all ferritin mRNAs and in the 3′ untranslated region of all transferrin receptor mRNAs. The IREs are bound by two related IRE-binding proteins (IRPs) which help control intracellular levels of Iron by regulating the expression of both ferritin and transferrin receptor genes. Multi-dimensional NMR and computational approaches were used to study the structure and dynamics of the IRE RNA in solution. The NMR data are consistent with formation of A-form helical stem regions, a one-base internal bulge and a Watson-Crick C·G base-pair between the first and fifth nucleotides in the loop. A superposition of refined structures indicates that the conserved C in the internal bulge, and three residues in the six-nucleotide hairpin loop are quite dynamic in this RNA. The structural roles of the stems, the loop and the bulge in the function of the IRE RNA and in possible interactions with the Iron regulatory protein are discussed.
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the Iron Responsive Element binding protein a target for synaptic actions of nitric oxide
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Samie R Jaffrey, Tracey A Rouault, Richard D. Klausner, Noam A Cohen, Solomon H SnyderAbstract:Abstract Molecular targets for the actions of nitric oxide (NO) have only been partially clarified. The dynamic properties of the Iron-sulfur (Fe-S) cluster of the Iron Responsive-Element binding protein (IRE-BP) suggested that it might serve as a target for NO produced in response to glutamatergic stimulation in neurons. In the present study, we demonstrate that N-methyl-D-aspartate, acting through NO, stimulates the RNA-binding function of the IRE-BP in brain slices while diminishing its aconitase activity. In addition, we demonstrate a selective localization of the IRE-BP in discrete neuronal structures, suggesting a potential role for this protein in the response of neurons to NO.
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the bifunctional Iron Responsive Element binding protein cytosolic aconitase the role of active site residues in ligand binding and regulation
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Caroline C Philpott, Richard D. Klausner, Tracey A RouaultAbstract:Abstract The Iron-Responsive Element binding protein/cytosolic aconitase functions as either an RNA binding protein that regulates the uptake, sequestration, and utilization of Iron or an enzyme that interconverts citrate and isocitrate. These mutually exclusive functions are regulated by changes in cellular Iron levels. By site-directed mutagenesis we show that (i) ligation of a [4Fe-4S] cluster is necessary to inactivate RNA binding and activate enzyme function in vivo, (ii) three of four arginine residues of the aconitase active site participate in RNA binding, and (iii) aconitase activity is not required for Iron-mediated regulation of RNA binding.
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the Iron Responsive Element binding protein localization of the rna binding site to the aconitase active site cleft
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: James P Basilion, Tracey A Rouault, Richard D. Klausner, Christina M Massinople, Wilson H BurgessAbstract:Abstract The Iron-Responsive Element-binding protein (IRE-BP) binds to specific stem-loop RNA structures known as Iron-Responsive Elements (IREs) present in a variety of cellular mRNAs (e.g., those encoding ferritin, erythroid 5-aminolevulinate synthase, and transferrin receptor). Expression of these genes is regulated by interaction with the IRE-BP. The IRE-BP is identical in sequence to cytosolic aconitase, and the function of the protein is determined by the presence or absence of an Fe-S cluster. The protein either functions as an active aconitase when the Fe-S cluster is present or as an RNA-binding protein when the protein lacks this cluster. Aconitase activity and IRE-binding activity are mutually exclusive, and interconversion between the two activities is determined by intracellular Fe concentrations. Mapping of the RNA-binding site of the IRE-BP by UV cross-linking studies defines a major contact site between IRE and protein in the active-site region. Modeling based on probable structural similarities between the previously crystallized mitochondrial aconitase and the IRE-BP predicts that these residues would be accessible to the IRE only were there a major change in the predicted conformation of the protein when cells are Iron-depleted.
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the interaction between the Iron Responsive Element binding protein and its cognate rna is highly dependent upon both rna sequence and structure
Nucleic Acids Research, 1993Co-Authors: Samie R Jaffrey, David J. Haile, Richard D. Klausner, Joe B HarfordAbstract:To assess the influence of RNA sequence/structure on the interaction RNAs with the Iron-Responsive Element binding protein (IRE-BP), twenty eight altered RNAs were tested as competitors for an RNA corresponding to the ferritin H chain IRE. All changes in the loop of the predicted IRE hairpin and in the unpaired cytosine residue characteristically found in IRE stems significantly decreased the apparent affinity of the RNA for the IRE-BP. Similarly, alteration in the spacing and/or orientation of the loop and the unpaired cytosine of the stem by either increasing or decreasing the number of base pairs separating them significantly reduced efficacy as a competitor. It is inferred that the IRE-BP forms multiple contacts with its cognate RNA, and that these contacts, acting in concert, provide the basis for the high affinity of this interaction.
David J. Haile - One of the best experts on this subject based on the ideXlab platform.
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the role of the Iron Responsive Element in the control of ferroportin1 ireg1 mtp1 gene expression
Journal of Hepatology, 2003Co-Authors: Athina Lymboussaki, David J. Haile, Elisa Pignatti, Giuliana Montosi, Cinzia Garuti, Antonello PietrangeloAbstract:Abstract Background/Aims : MTP1/Ferroportin1/IREG1, the product of the SLC40A1 gene, is a main Iron export protein in mammals. However, the way this gene is regulated by Iron is still unclear. The aim of this study was to investigate the functional role of genomic SLC40A1 Elements in response to Iron. Methods : Vectors containing either ∽2.6 kb 5′ flanking region or deletion constructs, including one devoid of an Iron Responsive Element ( SLC40A1 -ΔIRE-Luc), were analyzed by luciferase reporter gene in transfected HepG2, CaCO2 and U937 cells. Expression of Iron genes and activity of the Iron regulatory protein were also studied. Results : Iron increased and desferrioxamine decreased luciferase activity in all the cell types using both the full-length construct and the promoter deletion constructs, in the absence of changes in SLC40A1 or luciferase mRNA levels. To test the role of the SLC40A1 5′ untranslated region, we first demonstrated that wild type and not SLC40A1 -ΔIRE-Luc could bind Iron regulatory protein. Then, in cells transfected with SLC40A1 -ΔIRE-Luc, we found that, in spite of Iron regulatory protein activation, the response to Iron manipulation was lost. Conclusions : We demonstrate that the Iron Responsive Element in the SLC40A1 gene is functional and that it controls gene expression through the cytoplasmic Iron regulatory protein system.
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role of the ferroportin Iron Responsive Element in Iron and nitric oxide dependent gene regulation
Blood Cells Molecules and Diseases, 2002Co-Authors: Xiaobing Liu, David J. Haile, Ping HillAbstract:Abstract ABSTRACT The newly described Iron transporter, ferroportin (MTP1, IREG1), is expressed in a variety of tissues including the duodenum and cells of the mononuclear phagocyte system (MPS). In the MPS, ferroportin is hypothesized to be a major exporter of Iron scavenged from senescent erythrocytes. Changes in Iron metabolism, including the sequestration of Iron in the MPS, are characteristic of both acute and chronic inflammation and these conditions induce changes in ferroportin expression. In a mouse model of acute inflammation, LPS administration is associated with reduced MPS ferroportin protein and mRNA expression. In addition, the ferroportin 5′ UTR also has an Iron-Responsive Element that binds to the Iron-response proteins, but whether there is a role for this IRE in inflammation induced regulation of ferroportin has been unclear. A luciferase reporter gene under the control of the mouse ferroportin promoter and 5′ UTR was used to determine if this 5′ UTR conferred IRE-dependent regulation on this reporter gene. Stimulation of reporter gene transfected RAW 264.7 cells (a mouse macrophage cell line) with LPS resulted in IRE-dependent inhibition of luciferase production. Inhibitors of nitric oxide synthase abrogated the IRE-dependent effect of LPS. In addition, direct treatment of RAW 264.7 and with NO donor S-nitroso-N-acetylpenicillamine resulted in IRE-dependent down-regulation of luciferase expression. The effect of NO was consistent with IRP1/IRE mediated translation block. There are most likely both inflammation-mediated transcriptional and post-transcriptional (IRE-dependent) mechanisms for inhibiting ferroportin expression in MPS cells.
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the interaction between the Iron Responsive Element binding protein and its cognate rna is highly dependent upon both rna sequence and structure
Nucleic Acids Research, 1993Co-Authors: Samie R Jaffrey, David J. Haile, Richard D. Klausner, Joe B HarfordAbstract:To assess the influence of RNA sequence/structure on the interaction RNAs with the Iron-Responsive Element binding protein (IRE-BP), twenty eight altered RNAs were tested as competitors for an RNA corresponding to the ferritin H chain IRE. All changes in the loop of the predicted IRE hairpin and in the unpaired cytosine residue characteristically found in IRE stems significantly decreased the apparent affinity of the RNA for the IRE-BP. Similarly, alteration in the spacing and/or orientation of the loop and the unpaired cytosine of the stem by either increasing or decreasing the number of base pairs separating them significantly reduced efficacy as a competitor. It is inferred that the IRE-BP forms multiple contacts with its cognate RNA, and that these contacts, acting in concert, provide the basis for the high affinity of this interaction.
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modification of a free fe s cluster cysteine residue in the active Iron Responsive Element binding protein prevents rna binding
Journal of Biological Chemistry, 1993Co-Authors: Caroline C Philpott, David J. Haile, Tracey A Rouault, Richard D. KlausnerAbstract:The Iron-Responsive Element-binding protein (IRE-BP) binds to specific RNA stem-loop structures called Iron-Responsive Elements (IREs), which mediate the post-transcriptional regulation of a variety of genes involved in Iron metabolism. The IRE-BP is cytosolic aconitase, and a [4Fe-4S] cubane cluster is required for aconitase activity but is associated with loss of IRE binding affinity. Chemical modification of the IRE-BP can abrogate RNA binding and the 3 cysteines predicted to coordinate the Fe-S cluster in the IRE-BP could be targets for modification. We report the expression of recombinant IRE-BP in which the three putative cluster cysteines (Cys-437, Cys-503, and Cys-506) have been mutated to serine residues. Replacement of any or all of these cysteine residues results in a complete loss of aconitase activity. While all of the mutants bind RNA, substitution of Cys-437 specifically renders the IRE-BP resistant to inactivation by low concentrations of N-ethylmaleimide or diamide. These results identify Cys-437 as the target of in vitro regulation of RNA binding in the IRE-BP and suggest that, in the RNA-binding form of the protein, Cys-437 is free and therefore available for modifications that inhibit RNA binding.
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cellular regulation of the Iron Responsive Element binding protein disassembly of the cubane Iron sulfur cluster results in high affinity rna binding
Proceedings of the National Academy of Sciences of the United States of America, 1992Co-Authors: David J. Haile, Helmut Beinert, Joe B Harford, Tracey A Rouault, George A Blondin, Mary Claire Kennedy, Richard D. KlausnerAbstract:Abstract The translation of ferritin mRNA and degradation of transferrin receptor mRNA are regulated by the interaction of an RNA-binding protein, the Iron-Responsive Element binding protein (IRE-BP), with RNA stem-loop structures known as Iron-Responsive Elements (IREs) contained within these transcripts. IRE-BP produced in Iron-replete cells has aconitase (EC 4.2.1.3) activity. The protein shows extensive sequence homology with mitochondrial aconitase, and sequences of peptides prepared from cytosolic aconitase are identical with peptides of IRE-BP. As an active aconitase, IRE-BP is expected to have an Fe-S cluster, in analogy to other aconitases. This Fe-S cluster has been implicated as the region of the protein that senses intracellular Iron levels and accordingly modifies the ability of the IRE-BP to interact with IREs. Expression of the IRE-BP in cultured cells has revealed that the IRE-BP functions either as an active aconitase, when the cells are Iron-replete, or as an active RNA-binding protein, when the cells are Iron-depleted. We compare properties of purified authentic cytosolic aconitase from beef liver with those of IRE-BP from tissue culture cells and establish that characteristics of the physiologically relevant form of the protein from Iron-depleted cells resemble those of cytosolic aconitase apoprotein. We demonstrate that loss of the labile fourth Iron atom of the Fe-S cluster results in loss of aconitase activity, but that more extensive cluster alteration is required before the IRE-BP acquires the capacity to bind RNA with the affinity seen in vivo. These results are consistent with a model in which the cubane Fe-S cluster is disassembled when intracellular Iron is depleted.
Changliang Zhu - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning and preliminary function study of Iron Responsive Element binding protein 1 gene from cypermethrin resistant culex pipiens pallens
Parasites & Vectors, 2011Co-Authors: Wenbin Tan, Xiao Wang, Peng Cheng, Lijuan Liu, Haifang Wang, Maoqing Gong, Xin Quan, Honggang Gao, Changliang ZhuAbstract:Background Insecticide resistance jeopardizes the control of mosquito populations and mosquito-borne disease control, which creates a major public health concern. Two-dimensional electrophoresis identified one protein segment with high sequence homology to part of Aedes aegypti Iron-Responsive Element binding protein (IRE-BP).
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molecular cloning and preliminary function study of Iron Responsive Element binding protein 1 gene from cypermethrin resistant culex pipiens pallens
Parasites & Vectors, 2011Co-Authors: Wenbin Tan, Xiao Wang, Peng Cheng, Lijuan Liu, Haifang Wang, Maoqing Gong, Xin Quan, Honggang Gao, Changliang ZhuAbstract:Insecticide resistance jeopardizes the control of mosquito populations and mosquito-borne disease control, which creates a major public health concern. Two-dimensional electrophoresis identified one protein segment with high sequence homology to part of Aedes aegypti Iron-Responsive Element binding protein (IRE-BP). RT-PCR and RACE (rapid amplification of cDNA end) were used to clone a cDNA encoding full length IRE-BP 1. Real-time quantitative RT-PCR was used to evaluate the transcriptional level changes in the Cr-IRE strain Aedes aegypti compared to the susceptible strain of Cx. pipiens pallens. The expression profile of the gene was established in the mosquito life cycle. Methyl tritiated thymidine (3H-TdR) was used to observe the cypermethrin resistance changes in C6/36 cells containing the stably transfected IRE-BP 1 gene of Cx. pipiens pallens. The complete sequence of Iron Responsive Element binding protein 1 (IRE-BP 1) has been cloned from the cypermethrin-resistant strain of Culex pipiens pallens (Cr-IRE strain). Quantitative RT-PCR analysis indicated that the IRE-BP 1 transcription level was 6.7 times higher in the Cr-IRE strain than in the susceptible strain of 4th instar larvae. The IRE-BP 1 expression was also found to be consistently higher throughout the life cycle of the Cr-IRE strain. A protein of predicted size 109.4 kDa has been detected by Western blotting in IRE-BP 1-transfected mosquito C6/36 cells. These IRE-BP 1-transfected cells also showed enhanced cypermethrin resistance compared to null-transfected or plasmid vector-transfected cells as determined by 3H-TdR incorporation. IRE-BP 1 is expressed at higher levels in the Cr-IRE strain, and may confer some insecticide resistance in Cx. pipiens pallens.
Jack T. Rogers - One of the best experts on this subject based on the ideXlab platform.
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physiological and pathological role of alpha synuclein in parkinson s disease through Iron mediated oxidative stress the role of a putative Iron Responsive Element
International Journal of Molecular Sciences, 2009Co-Authors: David Olivares, Xudong Huang, Lars Branden, Nigel H Greig, Jack T. RogersAbstract:Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder after Alzheimer's disease (AD) and represents a large health burden to society. Genetic and oxidative risk factors have been proposed as possible causes, but their relative contribution remains unclear. Dysfunction of alpha-synuclein (alpha-syn) has been associated with PD due to its increased presence, together with Iron, in Lewy bodies. Brain oxidative damage caused by Iron may be partly mediated by alpha-syn oligomerization during PD pathology. Also, alpha-syn gene dosage can cause familial PD and inhibition of its gene expression by blocking translation via a newly identified Iron Responsive Element-like RNA sequence in its 5'-untranslated region may provide a new PD drug target.
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the 5 untranslated region of parkinson s disease α synuclein messengerrna contains a predicted Iron Responsive Element
Molecular Psychiatry, 2007Co-Authors: Avi L. Friedlich, Rudolph E. Tanzi, Jack T. RogersAbstract:The 5′-untranslated region of Parkinson's disease α -synuclein messengerRNA contains a predicted Iron Responsive Element
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an Iron Responsive Element type ii in the 5 untranslated region of the alzheimer s amyloid precursor protein transcript
Journal of Biological Chemistry, 2002Co-Authors: Jack T. Rogers, Hiromi Gunshin, Xudong Huang, Jeffrey Randall, Catherine M Cahill, Paul S Eder, Lorene M Leiter, Jay Mcphee, Satinder S Sarang, Tada UtsukiAbstract:Iron-Responsive Elements (IREs) are the RNA stem loops that control cellular Iron homeostasis by regulating ferritin translation and transferrin receptor mRNA stability. We mapped a novel Iron-Responsive Element (IRE-Type II) within the 5'-untranslated region (5'-UTR) of the Alzheimer's amyloid precursor protein (APP) transcript (+51 to +94 from the 5'-cap site). The APP mRNA IRE is located immediately upstream of an interleukin-1 Responsive acute box domain (+101 to +146). APP 5'-UTR conferred translation was selectively down-regulated in response to intracellular Iron chelation using three separate reporter assays (chloramphenicol acetyltransferase, luciferase, and red fluorescent protein reflecting an inhibition of APP holoprotein translation in response to Iron chelation. Iron influx reversed this inhibition. As an internal control to ensure specificity, a viral internal ribosome entry sequence was unResponsive to intracellular Iron chelation with desferrioxamine. Using RNA mobility shift assays, the APP 5'-UTRs, encompassing the IRE, bind specifically to recombinant Iron-regulatory proteins (IRP) and to IRP from neuroblastoma cell lysates. IRP binding to the APP 5'-UTR is reduced after treatment of cells with desferrioxamine and increased after interleukin-1 stimulation. IRP binding is abrogated when APP cRNA probe is mutated in the core IRE domain (Delta4 bases:Delta83AGAG86). Iron regulation of APP mRNA through the APP 5'-UTR points to a role for Iron in the metabolism of APP and confirms that this RNA structure can be a target for the selection of small molecule drugs, such as desferrioxamine (Fe chelator) and clioquinol (Fe, Cu, and Zn chelator), which reduce Abeta peptide burden during Alzheimer's disease.
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translational enhancement of h ferritin mrna by interleukin 1β acts through 5 leader sequences distinct from the Iron Responsive Element
Nucleic Acids Research, 1994Co-Authors: Jack T. Rogers, J L Andriotakis, Linda Lacroix, G P Durmowicz, K D Kasschau, Kenneth R BridgesAbstract:Interleukin-1 beta (Il-1 beta), a key cytokine in the acute phase response, elevates hepatic expression of both the heavy (H) and light (L) ferritin subunits without influencing the steady-state levels of either ferritin transcript. Transfection experiments with human hepatoma cells reveal that sequences within the 5' untranslated region (5'UTR) of H-ferritin mRNA confer translational regulation to chimaeric chloramphenicol acetyl transferase (CAT) mRNAs in response to Il-1 beta in the absence of marked changes in CAT mRNA levels. Il-1 beta dependent translational enhancement is mediated by a distinct G + C rich RNA sequence within 70 nucleotides (nt) of the start codon. The upstream Iron Responsive Element RNA stemloop does not confer increased expression to CAT mRNA in Il-1 beta stimulated hepatoma transfectants. A 38 nucleotide consensus sequence within the 5'UTRs of the mRNAs encoding the hepatic acute phase proteins alpha 1-antitrypsin (alpha 1AT), alpha 1-acid glycoprotein (AGP) and haptoglobin (Dente et al., 1985) is similar to sequences in the G + C rich H-ferritin mRNA translational regulatory Element. Deletion of three nucleotides from this region of the 61 nt G + C rich Element in the H-ferritin mRNA 5' leader eliminates Il-1 beta translational enhancement of the CAT reporter transcripts.
