The Experts below are selected from a list of 132 Experts worldwide ranked by ideXlab platform
Jamie E Craig - One of the best experts on this subject based on the ideXlab platform.
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a novel deletion in the ftl gene causes hereditary hyperferritinemia cataract syndrome hhcs by alteration of the transcription start site
Human Mutation, 2007Co-Authors: Kathryn P Burdon, Jamie E Craig, David A Mackey, Shiwani Sharma, Celia S. Chen, David P. DimasiAbstract:Hereditary hyperferritinemia cataract syndrome (HHCS) is characterized by distinctive cataracts and high serum ferritin in the absence of Iron overload. It is caused by mutations in the Iron Response Element (IRE) of the Ferritin Light Chain (FTL) gene. Here we investigate the genetics of HHCS in a three generation Australian kindred with typical HHCS ocular lens morphology and high ferritin levels. Initial sequencing of the IRE failed to detect any mutations. Sequencing of the entire gene including the promoter region revealed a novel 25 bp deletion upstream of the IRE abolishing the transcription start site. In lymphoblastoid cells, the deletion allele was transcribed from an alternate start site within the lower stem of the IRE and mutation carriers had high cellular L-ferritin levels. This novel deletion in the promoter encompassing the transcription start site of the FTL gene is responsible for HHCS in this kindred. The initial primers for amplifying the IRE similar to those used by other researchers failed to detect this mutation. Therefore the genomic region assessed in HHCS cases for diagnosis should be expanded to include mutations of this type. (c) 2007 Wiley-Liss, Inc.
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A novel deletion in the FTL gene causes hereditary hyperferritinemia cataract syndrome (HHCS) by alteration of the transcription start site.
Human mutation, 2007Co-Authors: Kathryn P Burdon, David A Mackey, Shiwani Sharma, Celia S. Chen, David P. Dimasi, Jamie E CraigAbstract:Hereditary hyperferritinemia cataract syndrome (HHCS) is characterized by distinctive cataracts and high serum ferritin in the absence of Iron overload. It is caused by mutations in the Iron Response Element (IRE) of the Ferritin Light Chain (FTL) gene. Here we investigate the genetics of HHCS in a three generation Australian kindred with typical HHCS ocular lens morphology and high ferritin levels. Initial sequencing of the IRE failed to detect any mutations. Sequencing of the entire gene including the promoter region revealed a novel 25 bp deletion upstream of the IRE abolishing the transcription start site. In lymphoblastoid cells, the deletion allele was transcribed from an alternate start site within the lower stem of the IRE and mutation carriers had high cellular L-ferritin levels. This novel deletion in the promoter encompassing the transcription start site of the FTL gene is responsible for HHCS in this kindred. The initial primers for amplifying the IRE similar to those used by other researchers failed to detect this mutation. Therefore the genomic region assessed in HHCS cases for diagnosis should be expanded to include mutations of this type.
Philippe Gros - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the Iron transporter DMT1 (NRAMP2/DCT1) in red blood cells of normal and anemic mk/mk mice.
Blood, 2001Co-Authors: François Canonne-hergaux, Prem Ponka, An Sheng Zhang, Philippe GrosAbstract:Divalent metal transporter 1 (DMT1) is the major transferrin-independent Iron uptake system at the apical pole of intestinal cells, but it may also transport Iron across the membrane of acidified endosomes in peripheral tissues. Iron transport and expression of the 2 isoforms of DMT1 was studied in erythroid cells that consume large quantities of Iron for biosynthesis of hemoglobin. In mk/mk mice that express a loss-of-function mutant variant of DMT1, reticulocytes have a decreased cellular Iron uptake and Iron incorporation into heme. Interestingly, Iron release from transferrin inside the endosome is normal in mk/mk reticulocytes, suggesting a subsequent defect in Fe(++) transport across the endosomal membrane. Studies by immunoblotting using membrane fractions from peripheral blood or spleen from normal mice where reticulocytosis was induced by erythropoietin (EPO) or phenylhydrazine (PHZ) treatment suggest that DMT1 is coexpressed with transferrin receptor (TfR) in erythroid cells. Coexpression of DMT1 and TfR in reticulocytes was also detected by double immunofluorescence and confocal microscopy. Experiments with isoform-specific anti-DMT1 antiserum strongly suggest that it is the non-Iron-Response Element containing isoform II of DMT1 that is predominantly expressed by the erythroid cells. As opposed to wild-type reticulocytes, mk/mk reticulocytes express little if any DMT1, despite robust expression of TfR, suggesting a possible effect of the mutation on stability and targeting of DMT1 isoform II in these cells. Together, these results provide further evidence that DMT1 plays a central role in Iron acquisition via the transferrin cycle in erythroid cells.
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characterization of the Iron transporter dmt1 nramp2 dct1 in red blood cells of normal and anemic mk mk mice
Blood, 2001Co-Authors: Francois Canonnehergaux, Prem Ponka, An Sheng Zhang, Philippe GrosAbstract:Divalent metal transporter 1 (DMT1) is the major transferrin-independent Iron uptake system at the apical pole of intestinal cells, but it may also transport Iron across the membrane of acidified endosomes in peripheral tissues. Iron transport and expression of the 2 isoforms of DMT1 was studied in erythroid cells that consume large quantities of Iron for biosynthesis of hemoglobin. In mk/mk mice that express a loss-of-function mutant variant of DMT1, reticulocytes have a decreased cellular Iron uptake and Iron incorporation into heme. Interestingly, Iron release from transferrin inside the endosome is normal in mk/mk reticulocytes, suggesting a subsequent defect in Fe(++) transport across the endosomal membrane. Studies by immunoblotting using membrane fractions from peripheral blood or spleen from normal mice where reticulocytosis was induced by erythropoietin (EPO) or phenylhydrazine (PHZ) treatment suggest that DMT1 is coexpressed with transferrin receptor (TfR) in erythroid cells. Coexpression of DMT1 and TfR in reticulocytes was also detected by double immunofluorescence and confocal microscopy. Experiments with isoform-specific anti-DMT1 antiserum strongly suggest that it is the non-Iron-Response Element containing isoform II of DMT1 that is predominantly expressed by the erythroid cells. As opposed to wild-type reticulocytes, mk/mk reticulocytes express little if any DMT1, despite robust expression of TfR, suggesting a possible effect of the mutation on stability and targeting of DMT1 isoform II in these cells. Together, these results provide further evidence that DMT1 plays a central role in Iron acquisition via the transferrin cycle in erythroid cells.
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cellular and subcellular localization of the nramp2 Iron transporter in the intestinal brush border and regulation by dietary Iron
Blood, 1999Co-Authors: Philippe Gros, Prem Ponka, Francois Canonnehergaux, Samantha GruenheidAbstract:Genetic studies in animal models of microcytic anemia and biochemical studies of transport have implicated the Nramp2 gene in Iron transport. Nramp2 generates two alternatively spliced mRNAs that differ at their 3′ untranslated region by the presence or absence of an Iron-Response Element (IRE) and that encode two proteins with distinct carboxy termini. Antisera raised against Nramp2 fusion proteins containing either the carboxy or amino termini of Nramp2 and that can help distinguish between the two Nramp2 protein isoforms (IRE: isoform I; non-IRE: isoform II) were generated. These antibodies were used to identify the cellular and subcellular localization of Nramp2 in normal tissues and to study possible regulation by dietary Iron deprivation. Immunoblotting experiments with membrane fractions from intact organs show that Nramp2 is expressed at low levels throughout the small intestine and to a higher extent in kidney. Dietary Iron starvation results in a dramatic upregulation of the Nramp2 isoform I in the proximal portion of the duodenum only, whereas expression in the rest of the small intestine and in kidney remains largely unchanged in Response to the lack of dietary Iron. In proximal duodenum, immunostaining studies of tissue sections show that Nramp2 protein expression is abundant under Iron deplete condition and limited to the villi and is absent in the crypts. In the villi, staining is limited to the columnar absorptive epithelium of the mucosa (enterocytes), with no expression in mucus-secreting goblet cells or in the lamina propria. Nramp2 expression is strongest in the apical two thirds of the villi and is very intense at the brush border of the apical pole of the enterocytes, whereas the basolateral membrane of these cells is negative for Nramp2. These results strongly suggest that Nramp2 is indeed responsible for transferrin-independent Iron uptake in the duodenum. These findings are discussed in the context of overall mechanisms of Iron acquisition by the body.
Rosaria Ingrassia - One of the best experts on this subject based on the ideXlab platform.
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1B/(−)IRE DMT1 Expression during Brain Ischemia Contributes to Cell Death Mediated by NF-κB/RelA Acetylation at Lys310
PloS one, 2012Co-Authors: Rosaria Ingrassia, Annamaria Lanzillotta, Ilenia Sarnico, Marina Benarese, Francesco Blasi, Laura Borgese, Fabjola Bilo, Laura E. Depero, Alberto Chiarugi, Pierfranco SpanoAbstract:The molecular mechanisms responsible for increasing Iron and neurodegeneration in brain ischemia are an interesting area of research which could open new therapeutic approaches. Previous evidence has shown that activation of nuclear factor kappa B (NF-κB) through RelA acetylation on Lys310 is the prerequisite for p50/RelA-mediated apoptosis in cellular and animal models of brain ischemia. We hypothesized that the increase of Iron through a NF-κB-regulated 1B isoform of the divalent metal transporter-1 (1B/DMT1) might contribute to post-ischemic neuronal damage. Both in mice subjected to transient middle cerebral artery occlusion (MCAO) and in neuronally differentiated SK-N-SH cells exposed to oxygen-glucose-deprivation (OGD), 1A/DMT1 was only barely expressed while the 1B/DMT1 without Iron-Response-Element (−IRE) protein and mRNA were early up-regulated. Either OGD or over-expression of 1B/(−)IRE DMT1 isoform significantly increased Iron uptake, as detected by total reflection X-ray fluorescence, and Iron-dependent cell death. Iron chelation by deferoxamine treatment or (−)IRE DMT1 RNA silencing displayed significant neuroprotection against OGD which concomitantly decreased intracellular Iron levels. We found evidence that 1B/(−)IRE DMT1 was a target gene for RelA activation and acetylation on Lys310 residue during ischemia. Chromatin immunoprecipitation analysis of the 1B/DMT1 promoter showed there was increased interaction with RelA and acetylation of H3 histone during OGD exposure of cortical neurons. Over-expression of wild-type RelA increased 1B/DMT1 promoter-luciferase activity, the (−)IRE DMT1 protein, as well as neuronal death. Expression of the acetylation-resistant RelA-K310R construct, which carried a mutation from lysine 310 to arginine, but not the acetyl-mimic mutant RelA-K310Q, down-regulated the 1B/DMT1 promoter, consequently offering neuroprotection. Our data showed that 1B/(−)IRE DMT1 expression and intracellular Iron influx are early downstream Responses to NF-κB/RelA activation and acetylation during brain ischemia and contribute to the pathogenesis of stroke-induced neuronal damage.
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1b ire dmt1 expression during brain ischemia contributes to cell death mediated by nf κb rela acetylation at lys310
PLOS ONE, 2012Co-Authors: Rosaria Ingrassia, Annamaria Lanzillotta, Ilenia Sarnico, Marina Benarese, Francesco Blasi, Laura Borgese, Fabjola Bilo, Laura E. Depero, Alberto Chiarugi, P F SpanoAbstract:The molecular mechanisms responsible for increasing Iron and neurodegeneration in brain ischemia are an interesting area of research which could open new therapeutic approaches. Previous evidence has shown that activation of nuclear factor kappa B (NF-κB) through RelA acetylation on Lys310 is the prerequisite for p50/RelA-mediated apoptosis in cellular and animal models of brain ischemia. We hypothesized that the increase of Iron through a NF-κB-regulated 1B isoform of the divalent metal transporter-1 (1B/DMT1) might contribute to post-ischemic neuronal damage. Both in mice subjected to transient middle cerebral artery occlusion (MCAO) and in neuronally differentiated SK-N-SH cells exposed to oxygen-glucose-deprivation (OGD), 1A/DMT1 was only barely expressed while the 1B/DMT1 without Iron-Response-Element (−IRE) protein and mRNA were early up-regulated. Either OGD or over-expression of 1B/(−)IRE DMT1 isoform significantly increased Iron uptake, as detected by total reflection X-ray fluorescence, and Iron-dependent cell death. Iron chelation by deferoxamine treatment or (−)IRE DMT1 RNA silencing displayed significant neuroprotection against OGD which concomitantly decreased intracellular Iron levels. We found evidence that 1B/(−)IRE DMT1 was a target gene for RelA activation and acetylation on Lys310 residue during ischemia. Chromatin immunoprecipitation analysis of the 1B/DMT1 promoter showed there was increased interaction with RelA and acetylation of H3 histone during OGD exposure of cortical neurons. Over-expression of wild-type RelA increased 1B/DMT1 promoter-luciferase activity, the (−)IRE DMT1 protein, as well as neuronal death. Expression of the acetylation-resistant RelA-K310R construct, which carried a mutation from lysine 310 to arginine, but not the acetyl-mimic mutant RelA-K310Q, down-regulated the 1B/DMT1 promoter, consequently offering neuroprotection. Our data showed that 1B/(−)IRE DMT1 expression and intracellular Iron influx are early downstream Responses to NF-κB/RelA activation and acetylation during brain ischemia and contribute to the pathogenesis of stroke-induced neuronal damage.
Pierfranco Spano - One of the best experts on this subject based on the ideXlab platform.
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1B/(−)IRE DMT1 Expression during Brain Ischemia Contributes to Cell Death Mediated by NF-κB/RelA Acetylation at Lys310
PloS one, 2012Co-Authors: Rosaria Ingrassia, Annamaria Lanzillotta, Ilenia Sarnico, Marina Benarese, Francesco Blasi, Laura Borgese, Fabjola Bilo, Laura E. Depero, Alberto Chiarugi, Pierfranco SpanoAbstract:The molecular mechanisms responsible for increasing Iron and neurodegeneration in brain ischemia are an interesting area of research which could open new therapeutic approaches. Previous evidence has shown that activation of nuclear factor kappa B (NF-κB) through RelA acetylation on Lys310 is the prerequisite for p50/RelA-mediated apoptosis in cellular and animal models of brain ischemia. We hypothesized that the increase of Iron through a NF-κB-regulated 1B isoform of the divalent metal transporter-1 (1B/DMT1) might contribute to post-ischemic neuronal damage. Both in mice subjected to transient middle cerebral artery occlusion (MCAO) and in neuronally differentiated SK-N-SH cells exposed to oxygen-glucose-deprivation (OGD), 1A/DMT1 was only barely expressed while the 1B/DMT1 without Iron-Response-Element (−IRE) protein and mRNA were early up-regulated. Either OGD or over-expression of 1B/(−)IRE DMT1 isoform significantly increased Iron uptake, as detected by total reflection X-ray fluorescence, and Iron-dependent cell death. Iron chelation by deferoxamine treatment or (−)IRE DMT1 RNA silencing displayed significant neuroprotection against OGD which concomitantly decreased intracellular Iron levels. We found evidence that 1B/(−)IRE DMT1 was a target gene for RelA activation and acetylation on Lys310 residue during ischemia. Chromatin immunoprecipitation analysis of the 1B/DMT1 promoter showed there was increased interaction with RelA and acetylation of H3 histone during OGD exposure of cortical neurons. Over-expression of wild-type RelA increased 1B/DMT1 promoter-luciferase activity, the (−)IRE DMT1 protein, as well as neuronal death. Expression of the acetylation-resistant RelA-K310R construct, which carried a mutation from lysine 310 to arginine, but not the acetyl-mimic mutant RelA-K310Q, down-regulated the 1B/DMT1 promoter, consequently offering neuroprotection. Our data showed that 1B/(−)IRE DMT1 expression and intracellular Iron influx are early downstream Responses to NF-κB/RelA activation and acetylation during brain ischemia and contribute to the pathogenesis of stroke-induced neuronal damage.
P F Spano - One of the best experts on this subject based on the ideXlab platform.
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1b ire dmt1 expression during brain ischemia contributes to cell death mediated by nf κb rela acetylation at lys310
PLOS ONE, 2012Co-Authors: Rosaria Ingrassia, Annamaria Lanzillotta, Ilenia Sarnico, Marina Benarese, Francesco Blasi, Laura Borgese, Fabjola Bilo, Laura E. Depero, Alberto Chiarugi, P F SpanoAbstract:The molecular mechanisms responsible for increasing Iron and neurodegeneration in brain ischemia are an interesting area of research which could open new therapeutic approaches. Previous evidence has shown that activation of nuclear factor kappa B (NF-κB) through RelA acetylation on Lys310 is the prerequisite for p50/RelA-mediated apoptosis in cellular and animal models of brain ischemia. We hypothesized that the increase of Iron through a NF-κB-regulated 1B isoform of the divalent metal transporter-1 (1B/DMT1) might contribute to post-ischemic neuronal damage. Both in mice subjected to transient middle cerebral artery occlusion (MCAO) and in neuronally differentiated SK-N-SH cells exposed to oxygen-glucose-deprivation (OGD), 1A/DMT1 was only barely expressed while the 1B/DMT1 without Iron-Response-Element (−IRE) protein and mRNA were early up-regulated. Either OGD or over-expression of 1B/(−)IRE DMT1 isoform significantly increased Iron uptake, as detected by total reflection X-ray fluorescence, and Iron-dependent cell death. Iron chelation by deferoxamine treatment or (−)IRE DMT1 RNA silencing displayed significant neuroprotection against OGD which concomitantly decreased intracellular Iron levels. We found evidence that 1B/(−)IRE DMT1 was a target gene for RelA activation and acetylation on Lys310 residue during ischemia. Chromatin immunoprecipitation analysis of the 1B/DMT1 promoter showed there was increased interaction with RelA and acetylation of H3 histone during OGD exposure of cortical neurons. Over-expression of wild-type RelA increased 1B/DMT1 promoter-luciferase activity, the (−)IRE DMT1 protein, as well as neuronal death. Expression of the acetylation-resistant RelA-K310R construct, which carried a mutation from lysine 310 to arginine, but not the acetyl-mimic mutant RelA-K310Q, down-regulated the 1B/DMT1 promoter, consequently offering neuroprotection. Our data showed that 1B/(−)IRE DMT1 expression and intracellular Iron influx are early downstream Responses to NF-κB/RelA activation and acetylation during brain ischemia and contribute to the pathogenesis of stroke-induced neuronal damage.
