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Labile Iron (labile + iron)
Selected AbstractsDietary vitamin E reduces labile iron in rat tissuesJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 5 2005Wissam Ibrahim Abstract Previous studies have shown that dietary vitamin E reduced generation and/or levels of superoxide. As superoxide has potential to release iron from its transport and storage proteins, and labile or available form of iron is capable of catalyzing the formation of reactive hydroxyl radicals, the effect of dietary vitamin E on labile iron pool was studied in rats. One-month-old Sprague-Dawley male and female rats were fed a basal vitamin E-deficient diet supplemented with 0, 20, 200, or 2,000 IU vitamin E/kg diet for 90 days. The levels of labile iron were measured in the liver, kidney, spleen, heart and skeletal muscle. Additionally, the levels of lipid peroxidation products were measured. The results showed that, except for labile iron in the heart of male rats, dietary vitamin E dose dependently reduced the levels of labile iron and lipid peroxidation products in all tissues of male and female rats. The findings suggest that dietary vitamin E may protect against oxidative tissue damage by reducing the generation and/or level of superoxide, which in turn attenuates the release of iron from its protein complexes. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:298,303, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20094 [source] Temporal responses in the disruption of iron regulation by manganeseJOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2006Catherine Kwik-Uribe Abstract Manganese (Mn) is an essential trace element, though at elevated exposures it is also a neurotoxicant. Several mechanisms underlying manganese toxicity have been investigated, although a consistent mechanism(s) of action at low exposures has not been fully elucidated. Here we systematically evaluated the effects of in vitro manganese exposure on intracellular iron (Fe) homeostasis and iron-regulatory protein (IRP) binding activity in undifferentiated PC12 cells over a range of manganese exposure concentrations (1, 10, 50, and 200 ,M MnCl2) and exposure durations (12, 24, 36, and 48 hr), to test the hypothesis that moderately elevated manganese exposure disrupts cellular iron regulation. Results demonstrate that manganese exposure produces a rapid and sustained dose-dependent dysregulation of cellular iron metabolism, with effects occurring as early as 12 hr exposure and at manganese doses as low as 1 ,M. Manganese exposure altered the dynamics of IRP-1 binding and the intracellular abundance of IRP-2, and altered the cellular abundance of transferrin receptor, ferritin, and mitochondrial aconitase protein levels. Cellular levels of labile iron were significantly increased with manganese exposure, although total cellular iron levels were not. The overall pattern of effects shows that manganese produced an inappropriate cellular response akin to iron deficiency, to which the cells were able to mount a compensatory response. Consistent with our previous studies, these data indicate that even low to moderate exposures to Manganese in vitro significantly disrupt cellular iron metabolism, which may be an important contributory mechanism of manganese neurotoxicity. © 2006 Wiley-Liss, Inc. [source] Staphylococcal NreB: an O2 -sensing histidine protein kinase with an O2 -labile iron,sulphur cluster of the FNR typeMOLECULAR MICROBIOLOGY, Issue 3 2004Annegret Kamps Summary The nreABC (nitrogen regulation) operon encodes a new staphylococcal two-component regulatory system that controls dissimilatory nitrate/nitrite reduction in response to oxygen. Unlike other two-component sensors NreB is a cytosolic protein with four N-terminal cysteine residues. It was shown that both the NreB,cysteine cluster and Fe ions are required for function. Isolated NreB was converted to the active form by incubation with cysteine desulphurase, ferrous ions and cysteine. This activation is typical for FeS-containing proteins and was reversed by oxygen. During reconstitution an absorption band at 420 nm and a yellow-brownish colour (typical for an FNR-type iron,sulphur cluster formation) developed. After alkylation of thiol groups in NreB and in the cysteine mutant NreB(C62S) almost no iron,sulphur cluster was incorporated; both findings corroborated the importance of the cysteine residues. Comparison of the kinase activity of (i) the reconstituted (ii) the unreconstituted, and (iii) the unreconstituted and deferrated NreB,His indicated that NreB kinase activity depended on iron availability and was greatly enhanced by reconstitution. NreB is the first direct oxygen-sensing protein described in staphylococci so far. Reconstituted NreB contains 4,8 acid-labile Fe and sulphide ions per NreB which is in agreement with the presence of 1,2 iron,sulphur [4Fe-4S]2+ clusters of the FNR-type. Unlike FNR, NreB does not act directly as transcriptional activator, but transfers the phosphoryl group to the response regulator NreC. [source] | ||||||||||