Selenoprotein Gene Nomenclature.

The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4, and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine sulfoxide reductase B1), and SEPHS2 (selenophosphate synthetase 2).

Rumen Microorganisms Decrease Bioavailability of Inorganic Selenium Supplements.

Despite the availability of selenium (Se)-enriched trace mineral supplements, we have observed low Se status in cattle and sheep offered traditional inorganic Se supplements. Reasons for this may include inadequate intake or low bioavailability of inorganic Se sources. The objective of this study was to determine whether rumen microorganisms (RMO) alter the bioavailability of Se sources commonly used in Se supplements.

Selenoprotein expression and function-selenoprotein W.

Selenoprotein W (SeW) is a small selenoprotein (85 to 88 amino acids) first identified in sheep suffering from selenium deficiency. The levels are highest in muscle, heart (except rodents) spleen and brain. The deduced amino acid sequence has been obtained for mice, rats, monkeys, humans, sheep, pigs, fish and chickens.

Mechanism for proliferation inhibition by various selenium compounds and selenium-enriched broccoli extract in rat glial cells.

The objective of this study was to investigate the differential effects of various selenium (Se) compounds and Se-enriched broccoli extracts on cell proliferation and the possible mechanism responsible for the Se-induced growth inhibition. C6 rat glial cells were incubated with graded concentrations up to 1000 nM of selenite, selenate, selenomethionine (SeM), Se-methyl-selenocysteine (SeMCys), high-Se broccoli (H-SeB) extract or low-Se broccoli (L-SeB) extract for 24 and 48 h. MTT results indicated that all Se sources and levels examined inhibited C6 cell proliferation at 48 h.

Selenoprotein W during development and oxidative stress.

Selenium is involved in prevention of cancer, heart and muscle diseases, is implicated in immune function, fertility and in delaying the aging process. Selenium deficiency is harmful to brain, heart and skeletal muscles. Selenoprotein W, a member of the selenoprotein family was expressed in developing nervous system, skeletal muscles and heart in mice.

Microarray analysis of selenium-depleted and selenium-supplemented mice.

Nutritional selenium deficiency is associated with Keshan disease in humans and white muscle disease in ruminant livestock. In this study, mice were fed a selenium-deficient diet for three generations. Female mice from the third depleted generation of these mice were given water containing either no added selenium or 0.

Deletion analysis of the rodent selenoprotein W promoter.

To identify regulatory elements in the rat selenoprotein W (SeW) promoter, 2090, 1265, 741, and 404 base pair truncations of genomic DNA lying immediately upstream of the SeW coding sequence were cloned into a luciferase reporter vector (pGL3-Basic from Promega, Madison, WI, USA). 3656 and 406 base pair mouse SeW promoter constructs were also compared. SeW promoter activity was assayed in two rat cell lines: L8 muscle cells and C6 brain cells.

Effect of dietary selenium restriction on selected parameters of selenium status in men with high life-long intake.

The influence of selenium (Se) restriction on disposition in plasma and urine fractions of infused (74)Se (selenite) was studied when adult males (Enshi City, Hubei Province, PRC) whose habitual daily Se intake is approximately 480 microg per day were transferred to Lichuan County, where the daily intake is approximately 30 microg. The subjects received an infusion (106 microg Se) on the day before consuming foods low in Se and a second infusion (113 microg Se) 63 days later. Blood and 24-hour urine samples were collected each day for 7 days after the first infusion and on days 22, 43, and 62 following the first infusion.

Identification of putative transcription factor binding sites in rodent selenoprotein W promoter.

To understand transcriptional regulation of the selenoprotein W (SeW) gene, we used in vitro binding assays to identify transcription factors that may be involved in the transcriptional regulation of the SeW gene. Using protein from rat C6 (glial) cell nuclear extracts, oligonucleotides containing putative regulatory elements in the SeW promoter and antibodies, we observed that specificity protein 1(Sp1) transcription factor binds to the Sp1 consensus sequence in the SeW promoter as well as to the metal response element (MRE). Although competition analysis showed specific binding at the TFII-1 site, super-shift analysis using anti-TFII-1 antibody did not yield any super-shifted band.

Metabolism of subtoxic level of selenite by double-perfused small intestine in rats.

Intestinal metabolism of the subtoxic level of selenite in rats was investigated using a double-perfusion system, which is an in situ, in vitro preparation in which the intestinal lumen and its vasculature are perfused simultaneously. The toxicity of sodium selenite was determined by inhibition of 3-O-methyl glucose (3MG) absorption and by histological examination. Levels of 1.

Selenium and its relationship to cancer: an update.

Selenomethionine (Semet) is the major seleno-compound in cereal grains and enriched yeast whereas Se-methylselenocysteine (SeMCYS) is the major seleno-compound in Se-accumulator plants and some plants of economic importance such as garlic and broccoli exposed to excess Se. Animals can metabolize both Semet and SeMCYS. Epidemiological studies have indicated an inverse relationship between Se intake and the incidence of certain cancers.

Selective production of rat mutant selenoprotein W with and without bound glutathione.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) and electrospray ionization mass spectrometry (ESI MS) analysis of a 6x His-tagged recombinant form of rat mutant selenoprotein W (RMSW) reveals that aerobic growth conditions primarily produce a form of RMSW without bound glutathione (10,305 Da) whereas anaerobic conditions produce a glutathione-bound (305 Da) form (10,610 Da). Purification of RMSW was achieved with a procedure employing acetone precipitation and DEAE-cellulose chromatography, in addition to Ni-NTA agarose chromatography. Additional steps, including polyvalent metal ion binding (PMIB) resin chromatography and CM-cellulose chromatography, were necessary after elution from the Ni-NTA agarose column, in order to maintain solubility of the purified protein.

Selenoprotein W gene regulation by selenium in L8 cells.

The effects of selenium on selenoprotein W gene expression were examined in cultured L8 rat skeletal muscle cells. Selenoprotein W contains selenium as selenocysteine in the primary protein structure and levels of this selenoprotein are affected by selenium. Northern blots indicated that there were no significant changes (P < 0.

Effect of copper, zinc and cadmium on the promoter of selenoprotein W in glial and myoblast cells.

Rat selenoprotein W (SeW) promoter activity was investigated using different concentrations of cadmium, copper, and zinc. Two fragments (404 and 1265 bp) of the SeW promoter, containing a single metal response element (MRE), were ligated into the multiple cloning site of a pGL3-Basic reporter plasmid. The constructs were transfected into cultured C6 (rat glial) and L8 (myoblast) cells and promoter activity measured by means of luciferase reporter gene fused to the SeW promoter fragments in the reporter plasmid.

Selenocompounds in plants and animals and their biological significance.

There are several selenocompounds in tissues of plants and animals. Selenate is the major inorganic selenocompound found in both animal and plant tissues. Selenocysteine is the predominant selenoamino acid in tissues when inorganic selenium is given to animals.

Antimutagenic activity of selenium-enriched green tea toward the heterocyclic amine 2-amino-3-methylimidazo[4,5-f]quinoline.

Both selenium and green tea have been reported to exhibit antigenotoxic and cancer chemopreventive properties. We compared the antimutagenic activities of regular green tea and selenium-enriched green tea obtained from Hubei Province, China, toward the heterocyclic amine, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in the Salmonella assay. Selenium-enriched green tea obtained by foliar application of selenite exhibited concentration-dependent inhibition of IQ-induced mutagenesis in the presence of rat liver S9 and was significantly more effective than regular green tea tested under the same conditions.

Selenium and the brain: a review.

Similar to other tissues selenium from selenomethionine is deposited in the brain at higher concentrations than selenium in other forms. Vitamin E has a greater effect than selenium in reducing lipid peroxidation in various brain regions. Selenium does not have as great effect on glutathione peroxidase (GPX) activity in the brain as in most other organs.

Urinary selenium and iodine during pregnancy and lactation.

The New Zealand environment is low in selenium and iodine, and is therefore ideally suited for the study of these anionic trace elements. The aim of this study was to determine urinary excretion of selenium and iodine during pregnancy and postpartum as part of an investigation of the influence of pregnancy and lactation on selenium metabolism in women of low selenium status. In a double-blind placebo-controlled study, 35 women in the earliest stages of pregnancy and 17 non-pregnant women were recruited in Dunedin, New Zealand.

Cancer-protective properties of high-selenium broccoli.

Selenium (Se) from high-Se garlic reduces the incidence of chemically induced mammary tumors, and Se from high-Se broccoli reduces colon cancer. However, the ability of Se from high-Se broccoli to protect against mammary cancer has not been tested. Also, the sprout form of broccoli contains many secondary plant compounds that are known to reduce cancer risk, but the anticarcinogenic activity of broccoli sprouts has not been investigated.

Selenoprotein W in overexpressed and underexpressed rat glial cells in culture.

Selenium deficiency results in undetectable levels of selenoprotein W (SeW) in muscle but has very little effect upon its content in the brain and thus rat glial cells were studied. Previous work showed that glutathione (GSH) is bound to SeW and this study was undertaken to elucidate its possible antioxidant functions. Full length cDNA of SeW was cloned to inducible LacSwitch expression vector and stably transfected in C6 rat glial cells.

Selenoprotein W: a review.

Purification of selenoprotein W (Se-W) from rat and monkey muscles was shown to exist in multiple forms: with or without reduced glutathione and/or a 41-Da moiety (identity still unknown). TGA is located at coding position 13 in Se-W complementary DNA (cDNA) from all five species studied (rats, mice, sheep, human and monkey). TGA is also the stop codon in the rodents and sheep cDNA, but TAA is the stop codon in primates.

Glutathione peroxidase activity and selenoprotein W levels in different brain regions of selenium-depleted rats(1).

Previous studies in selenium (Se)-depleted sheep and rats showed that selenoprotein W (SeW) levels decreased in all tissues except brain. To further investigate this depletion in different parts of the brain, second generation Se-depleted rats were used. Dams consumed a Se-deficient basal diet during gestation and lactation, and deficient rats were obtained by continuation on the same diet.

Tumorigenesis, metabolism, speciation, bioavailability, and tissue deposition of selenium in selenium-enriched ramps (Allium tricoccum).

Ramps (Allium tricoccum) were grown either in a mixture of vermiculite and peat moss or hydroponically with various concentrations of selenium as sodium selenate. The concentrations used were from 30 to 300 mg of selenium/kg of vermiculite-peat moss or from 10 to 120 mg/L in the hydroponic solutions. Levels as high as 784 mg of selenium/kg were obtained in the ramp bulbs when grown with high levels of selenium in the vermiculite-peat moss, and up to 600 mg of selenium/kg was obtained hydroponically.