SelW mRNA Expression Research Articles

Molecular cloning and sequence analysis of selenoprotein W gene and its mRNA expression patterns in response to metabolic status and cadmium exposure in goldfish, Carassius auratus.

Selenoprotein W (SelW) is a low molecular weight and selenocysteine containing protein with redox activity involved in the antioxidant response. In the present study, the full-length cDNA of goldfish (Carassius auratus) selenoprotein W (gfSelW) was successfully cloned from the liver tissue by rapid amplification of cDNA ends technique. The obtained gfSelW cDNA was 730 bp long with a 79 bp 5'-untranslated region (UTR), a 390 bp 3'-UTR containing the consensus polyadenylation signal AATAAA and a 261 bp open reading frame coding a protein of 86 amino acid residues. gfSelW mRNA was observed in all regions of brain and peripheral tissues by semi-quantitative RT-PCR, and the most abundant was detected in testis. After fasting for 1 week, gfSelW mRNA expression levels were significantly decreased compared to the fed group in hypothalamus and liver. After refeeding for 7 days, gfSelW mRNA expression levels were increased back. Furthermore, the mRNA expressions of gfSelW in hypothalamus and liver were varied in periprandial changes and significantly up-regulated after meal 2 h and 4 h, respectively. With cadmium exposure for 24 h, gfSelW mRNA expression levels in gill and leucocytes were significantly decreased at different cadmium concentrations changing from 0.5 ppm to 10 ppm. However, the gfSelW mRNA expression level was sharply increased in liver, relatively to the control about 4.98-fold at 0.5 ppm. The results in this study provide molecular characterization of SelW in goldfish and imply that SelW mRNA expression may be associated with metabolic status and oxidative stress and regulated by metabolic factors and cadmium in fish.

The role of selenoprotein W in inflammatory injury in chicken immune tissues and cultured splenic lymphocyte.

Selenoprotein W (SelW) is mainly understood in terms of its antioxidant effects in the cellular defense system. Inflammation is an important indicator of animal tissue injury, and the inflammatory cells may trigger a sophisticated and well-orchestrated inflammatory cascade, resulting in exaggerated oxidative stress. To investigate the role of SelW in inflammatory injury in chicken immune tissues and cultured splenic lymphocyte, in this report, the effects of selenium (Se) on mRNA expressions of SelW and inflammatory factors (iNOS, COX-2, NF-κB, PTGEs, and TNF-α) in the chicken immune organs (spleen, thymus and bursa of Fabricius) and cultured splenic lymphocyte treated with sodium selenite and H2O2, or knocked down SelW with small interfering RNAs (siRNAs) were examined. The results showed that Se-deficient diets effectively decreased the mRNA expression of SelW (P < 0.05), and induced a significantly up-regulation of COX-2, iNOS, NF-κB, PTGEs and TNF-α mRNA levels (P < 0.05). The histopathological analysis showed that immune tissues were obviously injured in the low-Se groups. In vitro, H2O2 induced a significantly up-regulation of the mRNA levels of inflammation-related genes (iNOS, COX-2, NF-κB, PTGEs, and TNF-α) in cultured splenic lymphocyte (P < 0.05). When lymphocytes were pretreated with Se before treated with H2O2, the inflammation-related genes were significantly decreased (P < 0.05). Silencing of SelW significantly up-regulated the inflammation-related genes (iNOS, COX-2, NF-κB, PTGEs, and TNF-α) in cultured splenic lymphocyte (P < 0.05). The results suggested that the expression levels of inflammatory factors (iNOS, COX-2, NF-κB, PTGEs, and TNF-α) and SelW can be influenced by Se in birds. SelW commonly played an important role in the protection of immune organs of birds from inflammatory injury by the regulations of inflammation-related genes.

Possible correlation of selenoprotein W with inflammation factors in chicken skeletal muscles.

The aim of the present study was to investigate the possible correlation of selenoprotein W (SelW) with inflammatory injury induced by dietary selenium (Se) deficiency in chicken. One-day-old male chickens were fed either a commercial diet or a Se-deficient diet for 55days. Then, the expression levels of SelW messenger RNA (mRNA) and inflammation-related genes (NF-κB, TNF-α, iNOS, COX-2, and PTGES) in chicken skeletal muscles (wing muscle, pectoral muscle, and thigh muscle) were determined at 15, 25, 35, 45, and 55days old, respectively. In addition, the correlation between SelW mRNA expression and inflammation-related genes were assessed. The results showed that dietary Se deficiency reduced the mRNA expression of SelW in chicken wing, pectorals, and thigh muscles. In contrast, Se deficiency increased the mRNA expression levels of inflammation-related genes in chicken skeletal muscle tissues at different time points. The Pearson's correlation coefficients showed that the mRNA expression levels of inflammation-related genes were significantly negative related to SelW (p < 0.05). These data showed that Se deficiency induced the inflammatory response in chicken skeletal muscle. As one important selenoprotein gene in skeletal muscles, SelW may play a role in the regulation of inflammation reaction in Se-deficiency myopathy.

Antioxidative role of selenoprotein W in oxidant-induced chicken splenic lymphocyte death

To verify the antioxidative role of SelW in oxidant-induced chicken splenic lymphocyte, in this report, the influence of selenite supplementation and SelW gene silence on H2O2-mediated cell viability and cell apoptosis in cultured splenic lymphocyte derived from spleen of chicken were examined. The cultured cells were treated with sodium selenite and H2O2, or knocked down SelW with small interfering RNAs (siRNAs). The lymphocytes were examined for cell viability, cell apoptosis and mRNA expression levels of SelW and apoptosis-related genes (Bcl-2, Bax, Bak-1, caspase-3 and p53). The results show that the mRNA expression of SelW were effectively increased after treatment with sodium selenite, and H2O2-induced cell apoptosis was significantly decreased and cell viability was significantly increased. 20 μM H2O2 was found to induce cell apoptosis and decrease cell viability, which was alleviated obviously when cells were pretreated with sodium selenite before exposure to 20 μM H2O2. Meanwhile, H2O2 induced a significantly up-regulation of the Bax/Bcl-2 ratio, Bax, Bak-1, caspase-3 and p53 and down-regulation of Bcl-2 (P < 0.05). When lymphocytes were pretreated with Se before treated with H2O2, the Bax/Bcl-2 ratio and mRNA expression of those genes were significantly decreased, and Bcl-2 was increased (P < 0.05). SelW siRNA-transfected cells were more sensitive to the oxidative stress induced by treatment of H2O2 than control cells. Silencing of the lymphocyte SelW gene decreased their cell viability, and increased their apoptosis rate and susceptibility to H2O2. Silencing of SelW significantly up-regulated the Bax/Bcl-2 ratio, Bax, Bak-1, caspase-3 and p53 and down-regulated Bcl-2 (P < 0.05). The present study demonstrates that SelW plays an important role in protection of splenic lymphocyte of birds from oxidative stress.

Possible Correlation between Selenoprotein W and Myogenic Regulatory Factors in Chicken Embryonic Myoblasts

The biological function of selenium (Se) is mainly elicited through Se-containing proteins. Selenoprotein W (SelW), one member of the selenoprotein family, is essential for the normal function of the skeletal muscle system. To investigate the possible relationship of Se in the process of differentiation in chicken myoblasts and the expression of SelW, the cultured chicken embryonic myoblasts were incubated with sodium selenite at different concentrations for 72h, and then the mRNA levels of SelW and myogenic regulatory factors (MRFs) in myoblasts were determined at 12, 24, 48, and 72h, respectively. Furthermore, the correlation between SelW mRNA expression and MRF mRNA expression was assessed. The results showed that the sodium selenite medium enhanced the mRNA expression of SelW, Myf-5, MRF4, and myogenin in chicken myoblasts. The mRNA expression levels of MRFs were significantly correlated with those of SelW at 24, 48, and 72h. These data demonstrate that Se is involved in the differentiation of chicken embryonic myoblasts, and SelW showed correlation with MRFs.

Effects of Selenoprotein W gene expression by selenium involves regulation of mRNA stability in chicken embryos neurons

Selenium (Se) and Selenoprotein W (SelW) plays a pivotal role in the brain development, function, and degeneration and that SelW expression in the brain may be affected by Se. However, the mechanism which Se regulates the SelW gene expression in neurons remains to be unclear. To investigate the effects of the SelW gene expression and mRNA stability induced by Se, primary cultured chicken embryos neurons derived from 8-day-old chick embryo cerebral hemispheres were treated with 10(-9)-10(-5) mol/l Se as selenite for 3, 6, 12, 24 or 48 h, respectively. The morphology and viability of Neurons was detected. The SelW mRNA expression level and mRNA half-life was examined in Se-treated neurons. The relative low concentrations of Se enhanced the neurite outgrowth, increased the SelW mRNA levels and elevated the mRNA half-life of chick embryo neurons. In contrast, the high concentrations of Se presented neurotoxic to neurons, decreased the SelW mRNA levels and reduced the mRNA half-life of neuronal cells. These results suggest that the alteration of post-transcriptional stabilization of SelW mRNA is an important mechanism of Se-induced the elevation or reduction of the SelW expression level in chick embryo neurons.

Selenium Regulates Gene Expression of Selenoprotein W in Chicken Gastrointestinal Tract

Selenoprotein W (SelW) is an existing form of selenium (Se). Se influences the levels of SelW in mammals. However, little is known about the pattern of SelW expression in the gastrointestinal tract tissue of bird. The present paper describes the effects of different dietary levels of Se on the SelW mRNA expression in the gastrointestinal tract tissue of chicken. The expression levels of SelW mRNA and the Se contents in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum) were determined on days 15, 25, 35, 45, and 55, respectively. The results showed that the Se contents and the SelW mRNA expression were significantly higher (p < 0.05) in the high-Se group, and the Se contents and SelW mRNA expression in the low-Se group were significantly lower (p < 0.05) than in the controls. The Se contents were the highest in the duodenum and the lowest in the rectum, while the SelW mRNA expression was the highest in the gizzard and the lowest in the rectum. In addition, the SelW mRNA levels in the gastrointestinal tract tissue were found to increase in a time-dependent manner with increasing feeding time. Furthermore, the expression of the SelW mRNA in the gastrointestinal tract tissues of chickens was found to correlate with the dietary Se concentrations, but not with the tissue Se contents.

Selenium Regulates Gene Expression of Selenoprotein W in Chicken Skeletal Muscle System

Selenoprotein W (SelW) is abundantly expressed in skeletal muscles of mammals and necessary for the metabolism of skeletal muscles. However, its expression pattern in skeletal muscle system of birds is still uncovered. Herein, to investigate the distribution of SelW mRNA in chicken skeletal muscle system and its response to different selenium (Se) status, 1-day-old chickens were exposed to various concentrations of Se as sodium selenite in the feed for 35 days. In addition, myoblasts were treated with different concentrations of Se in the medium for 72 h. Then the levels of SelW mRNA in skeletal muscles (wing muscle, pectoral muscle, thigh muscle) and myoblasts were determined on days 1, 15, 25, and 35 and at 0, 24, 48, and 72 h, respectively. The results showed that SelW was detected in all these muscle components and it increased both along with the growth of organism and the differentiation process of myoblasts. The thigh muscle is more responsive to Se intake than the other two skeletal muscle tissues while the optimal Se supplementation for SelW mRNA expression in chicken myoblasts was 10(-7) M. In summary, Se plays important roles in the development of chicken skeletal muscles. To effect optimal SelW gene expression, Se must be provided in the diet and the media in adequate amounts and neither at excessive nor deficient levels.

Effects of Dietary Selenium on Selenoprotein W Gene Expression in the Chicken Immune Organs

Selenoprotein W (SelW) is expressed in the immune systems of mammals. However, its pattern of expression in the immune organs of birds is still unclear. To investigate the distribution of SelW and effects of dietary Se levels on the SelW mRNA expression in the immune organs of birds, 1-day-old male chickens were fed either a commercial diet or an Se-supplemented diet containing 0.601, 1.058, 1.514, or 2.427mg Se per kilogram, and 1.0, 2.0, 3.0 or 5.0mg sodium selenite per kilogram for 90days. The immune organs (spleen, thymus, and bursa of Fabricius) were collected and examined for Se content and SelW mRNA levels. The mRNA expression of SelW was detected in all the tissues. Although Se content was the highest in the spleen, the remarkable stability of the SelW mRNA level was observed in this organ during different times of dietary Se supplementation. Se-supplemented diet can make the SelW expression levels higher within a certain range in thymus and bursa of Fabricius. The present study demonstrates that SelW is widely expressed in immune organs of birds and that Se-supplementation of the feed increases SelW expression in the thymus and the bursa of Fabricius.

Dietary Selenium Affects Selenoprotein W Gene Expression in the Liver of Chicken

As selenium in the form of "Selenoprotein W (SelW)" is essential for the maintenance of normal liver function, the expression of SelW liver depends on the level of selenium supplied with the diet. Whereas this is well known to be the case in mammals, relatively little is known about the effect of dietary Se on the expression SelW in the livers of avian species. To investigate the effects of dietary Se levels on the SelW mRNA expression in the liver of bird, 1-day-old male chickens were fed either a commercial diet or a Se-supplemented diet containing 1.0, 2.0, 3.0, and 5.0mg/kg sodium selenite (Na(2)SeO(3)) for 90days. The livers were collected and examined for Se content and mRNA levels of SelW, Selenophosphate synthetase-1, and selenocysteine-synthase (SecS). The data indicate that, within a certain range, a Se-supplemented diet can increase the expression of SelW and the mRNA levels of SecS, and also, that the transcription of SelW is very sensitive to dietary Se.

Selenoprotein W gene expression in the gastrointestinal tract of chicken is affected by dietary selenium

Selenoprotein W (SelW) and selenium (Se) plays important roles in gastrointestinal function and that SelW expression in the gastrointestinal system of mammals is sensitive to Se levels. However, little is known about the pattern of SelW expression in the bird gastrointestinal tract. To investigate the distribution of SelW and effects of dietary Se levels on the SelW mRNA expression in the gastrointestinal tract tissues of birds, 1-day-old male chickens were fed either a commercial diet or a Se-supplemented diet containing 1.0, 2.0, 3.0 or 5.0mg/kg sodium selenite for 90days. The gastrointestinal tract tissues (tongue, esophagus, crop, proventriculus, gizzard, duodenum, small intestine, cecum and rectum) were collected and examined for Se content and mRNA levels of SelW. The mRNA expression of SelW was detected in all tissues. The greatest increase in SelW mRNA levels was observed in the gizzard, whereas Se content was highest in the duodenum and small intestine. A significant increase in SelW mRNA levels was observed in the gastrointestinal tract tissues of chickens fed the diets containing 1-3mg/kg sodium selenite while decreased SelW mRNA levels were observed in the esophagus, crop, proventriculus, gizzard, duodenum and cecum in chickens fed the diet containing 5mg/kg sodium selenite. These data indicate that SelW is widely expressed in the gastrointestinal tract tissues of birds and the transcription of the SelW gene is very sensitive to dietary Se.