Pervez Ahmed Khoso

Different responses of selenoproteins to the altered expression of selenoprotein W in chicken myoblasts

The aim of the present study was to examine the role of Selenoprotein W (Sepw1) in modulating the expression of other selenoproteins. In the present study, we silenced and overexpressed the expression of Sepw1 in chicken myoblasts and subsequently treated the myoblasts with a reactive oxygen species (ROS) scavenger, N-acetyl-L-cysteine (NAC), and H2O2. Thereafter, the levels of expression of 25 selenoproteins and the activities of certain antioxidative enzymes, glutathione peroxidase (Gpx), superoxide dismutase (SOD), and catalase (CAT) were analyzed. In addition, principal component analysis (PCA) was used to define the most important parameters that could be used as key factors. The results indicated that as a highly expressed selenoprotein (only lower than Gpx1, Selk, Sels and Sep15), Sepw1 could interact with H2O2 (P < 0.05) and influence the expression of some selenoproteins (Gpx3, Gpx4, Txnrd1, Selt, Selh, Sepp1, Sels and Sep15, P < 0.05) and the sensitivity of the cells to H2O2. Both the overexpression and silencing of Sepw1 influenced the mRNA levels of selenoproteins. However, the responses of selenoproteins to altered Sepw1 expression were different. The results indicated that Sepw1 played a special role in H2O2 metabolism and may modulate the expression of certain selenoproteins through the redox pathway. Therefore, these results indicate that Sepw1 is an essential antioxidative selenoprotein in chicken myoblasts.

SelW regulates inflammation-related cytokines in response to H2O2 in Se-deficient chicken liver

Selenium (Se) deficiency-induced liver damage is related to oxidative stress, and the alternative transcription of cytokines has been linked to liver disease. Selenoprotein W (SelW) is known to play an antioxidant role in mammals, but chicken SelW does not possess a cysteine at residue 37 that is required for the presumed antioxidant function in mammals. The relationship between SelW and cytokines in H2O2-mediated chicken liver damage remains unclear. To investigate the protective role of SelW against H2O2 by influencing the expression of cytokine mRNAs, SelW was overexpressed or/and knocked down in cultured chicken liver cells. After the cells were exposed to H2O2, the levels of interleukin (IL)-1, IL-6, IL-8, IL-17, IL-4, IL-10 and IFN-γ were lower in the SelW over-expressing cells but higher in the SelW knockdown cells compared to the H2O2-only treatment group. Meanwhile, chicken were fed with a Se-deficient granulated diet containing 0.032 mg kg−1 Se for 15, 25, 35, 45 and 55 days, and the results showed that IL-1, IL-6, IL-8, IL-17, IL-4, IL-10 and IFN-γ in Se-deficient chicken liver and serum were dramatically higher than the normal control group. In conclusion, our findings suggested that SelW regulated inflammation-related cytokines during H2O2-dependent chicken liver damage.

Effects of avermectin on heat shock proteins expression and histopathology in spleen tissues of pigeon.

Avermectin (AVM) is the active component of some insecticidal and nematicidal product used in agriculture and veterinary medicine for the prevention of parasitic diseases. Residues of AVM in environment have toxic effects on non-target aquatic and terrestrial organisms. Heat shock proteins (Hsps) are commonly used by environmental toxicologists as biochemical markers of exposure to various chemical and other stressors. The objective of this study was to investigate whether sub-chronic AVM exposure would alter the levels of stress proteins, Hsps in the pigeon spleen after 30, 60 and 90days. Our results showed that Hsp60, Hsp70 and Hsp90, and their corresponding messenger RNA (mRNA) transcriptions (as well as Hsp30) significantly elevated, meanwhile, obviously histopathological changes were not observed in pigeons spleens after early AVM exposure. Then the expression of Hsps relatively decreased and obvious histopathological damages occurred in the spleen tissues with continued AVM exposure. So we suggest that the elevations of Hsps can be as a part of protective mechanism to reduce cellular damage, and important markers to help assess the toxicity induced by AVM. The reduction of Hsps in spleen implies that the tissues are damaged by long-term and excessive AVM exposure. Thus, the information presented in this study is believed to be helpful in supplementing data for further AVM toxicity study.

Avermectin induced global DNA hypomethylation and over-expression of heat shock proteins in cardiac tissues of pigeon

Despite increasing evidences pointing to residues of avermectin (AVM) pose toxic effects on non-target organisms in environment, but the data in pigeon is insufficient. The alteration of global DNA methylation and response of heat shock proteins (Hsps) are important for assessing the AVM toxicity in cardiac tissues of pigeon (Columba livia). To investigate the effects of AVM exposure in cardiac tissues of pigeon, we detected the expression levels of DNA methyltransferases (Dnmts), methylated DNA-binding domain protein 2 (MBD2), and Hsp 60, 70 and 90. Pigeons were exposed to feed containing AVM (0, 20, 40 and 60mg/kg diet) for 30, 60, 90days respectively, and cardiac tissues were collected and analyzed. We found the transcriptional levels of Dnmt1, Dnmt3a and Dnmt3b mRNA were down-regulated, but the transcriptional levels of MBD2 mRNA were up-regulated by AVM exposure in cardiac tissues of pigeon. Necrocytosis, hemorrhage, infiltration of inflammatory cells and abundant vacuoles appeared in cardiac tissues after AVM exposure. Accompanying this phenotype, the mRNA transcriptional and/or protein levels of Hsp30, Hsp60, Hsp70 and Hsp90 increased. In conclusion, these results underscored AVM exposure caused DNA methylation machinery malfunctions, and induced over-expression of Hsps to improve the protective function against cardiac injury.