Dissertation
Dissertation > Agricultural Sciences > Livestock, animal medicine,hunting,silkworm,bee > Animal Medicine ( Veterinary Medicine) > Livestock, poultry, wildlife diseases > Poultry > Chicken

The Analysis of the Antioxidant Function of Selenoprotein W and Its Role in Selenium-Deficiency Induced Apoptosis in Skeletal Muscles Cells of Chick

Author YaoHaiDong
Tutor XuShiWen
School Northeast Agricultural University
Course Clinical Veterinary Medicine
Keywords Selenium Apoptosis Selenoprotein W Antioxidant Chick Sekletal muscle cells
CLC S858.31
Type Master's thesis
Year 2013
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Selenium (Se) is one of the essential microelement for human and animals. Dietary Sedeficiency has been shown to give rise to the development of several diseases. The damage ofskeletal muscles represents a classical Se/vitamin E deficiency disease in chicks. In recent years,some studies showed that physiological functions of Se are considered to be mediated throughselenoproteins. So it is important to study the role of Se in the expression of selenoproteins inSe-deficiency disease. It was shown that endoplasmic reticulum resident selenoproteins, Sepn1,Selt, Selk, Sels, and Selw play important role in the regulation of oxidative stress, calciumhomeostasis, development of muscle. In addition, dietary Se could influence the expression ofselenoproteins. So it is very important to study the effect of Se-deficiency on the expression ofselenoproteins and the relationship of selenoproteins and Se-deficiency muscle disease.Compared with the mammalian homologues, the chicken SelW has its own characteristics.There are32amino acid differences between the peptide sequences of rat and chicken SelW.Although chicken SelW contains a conserved10CXXU13motif, it has no Cys at residue37(Cys37)that is necessary for the anti-oxidative function in rats. Whether the structural deviation of chickenSelW from that of mammalian species affected its anti-oxidative function was unclear. In thepresent study, Se deficient chick modle was contructed. Then the expression levels of Sepn1, Selt,Selk, Sels, Sepsecs, Sephs1, oxidative stress, and cell apoptosis levels in pectoral, wing and thighmuscles were examined. And the relationship selenoproteins and oxidative damage was analyzed.In addition, small interfering RNAs (siRNAs) technology was applied to suppress the SelWexpression in chicken embryonic myoblasts. Thereafter, these myoblasts were treated with differentconcentrations of H2O2or NAC and assayed for cell viability, apoptosis rate, reactive oxygenspecies (ROS) status, and expression levels of apoptosis-related genes and proteins. The resultsshowed that:1. Se deficiency induced different levels of oxidative damage, such as decreased Gpx activitiesand increased MDA levels, in the thigh, pectoral, and wing muscles of chicks. All these responseswere stronger in the pectoral muscle than in the thigh and wing muscles. The high susceptibility and elevated oxidative cell death in the pectoral muscle might be related to its unique expressionpatterns of the4ER resident selenoprotein genes, Sepn1, Selt, Selk, Sels and GPx activity.2. The expression of3ER resident selenoprotein genes was closely related to that of Sepsecsin the3skeletal muscles, but no such correlation was found between Sephs1and any of thoseselenoprotein genes. The results indicated that Se influenced the expression of selenoproteins bythe regulation of Sepsecs.3. Se deficiency and the knockdown of SelW induced apoptosis in skeletal muscle cells andthe increased Bax, Caspase-3and p53expression and decreased Bcl-2protein levels. The resultsindicated that the apoptosis induced by Se deficiency and the knockdown of SelW was related tothe regulation of apoptosis genes Bax, Bcl-2, Caspase-3and p53.4. These myoblasts were treated with different concentrations of H2O2after SelW RNAi.Notably, mRNA and protein levels of SelW in the myoblasts were down-regulated by H2O2in adose-dependent fashion. And the ROS levels were increased in SelW deleted cells. The treatmentwith NAC after SelW RNAi increased the sensitivity of cells to H2O2, and decreased the ROSlevels. And the oxidative injuries by the SelW knockdown were reversed by the co-treatment ofNAC, which reveal the antioxidant function of chicken SelW in embryonic myoblasts.

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