Mechanism Research On The Inhibition Of Oxr1 By Mir-30b In Cardiac Muscle Apoptosis Induced By Selenium Deficiency In Chicken

Selenium is a necessary trace element for humans and animals. Dietary selenium deficiency can cause a series of selenium deficiency diseases. Myocardial injury is a typical pathological change of chicken selenium deficiency diseases. So it has great significance for the study of the development of mechanisms and biological indicators of myocardial injury caused by selenium deficiency.Micro RNAs have been a research focus in recent years. In 1993 scientists have found micro RNA(lin-4) in Caenorhabditis elegans at the first time, In 2001 Nature Science reported they found a similar lin-4 small molecule RNA in C. elegans Drosophila, thus they named it as micro RNA. Micro RNA is about 19~25nt long non-coding RNA, widely found in eukaryotes. Based on current research reports, we found that micro RNA can regulate the translation of thousands of genes, but there are still many unknown regulatory relationships. At the same time more and more evidence suggest that micro RNAs involved in several biological processes. And many studies have shown that micro RNAs also play an important role in the development of heart disease. After a review of the paper, we found mir-30 b may have relationship with the heart disease greatly, and also with the selenium. So we choose mir-30 b for our study and research the role of mi R-30 b in selenium-deficient myocardial apoptosis.1. On the basis of the consruction of overexpression and knockdown of mir-30 b in chicken myocardial cells, we detected the overexpression of mir-30 b as 67 times, and knockdown of mir-30 b is 0.43 times. Using bioinformatics software Target Scan and Mi RDB predicted for mir-30 b target genes, we use the luciferase report gene and RT-PCR methods to verify the target genes Oxr1 of mir-30 b.2. Low selenium diet can cause mir-30 b expression increased and Oxr1 expression decreased in myocardial tissue, mir-30 b increases 9.74 times, Oxr1 expression decreases 99 times, compared with the control group(P < 0.05); Apoptosis gene Caspase-3 and Bax expression level, compared with the control group have significant difference(P < 0.05) and apoptosis suppression gene Bcl-2 significantly lower than control group, and by the observation of ultraconstruction of cardiac muscle found that myocardial apoptosis increased significantly.Myocardial tissue oxidative stress, GPx, SOD, CAT, GSH activity decline, H2O2, · OH, i NOS activity, NO and MDA levels increased.The results show that mir-30 b and its target genes Oxr1 could cause myocardial apoptosis induced by oxidative stress in selenium deficiency chicken.3. On the basis of the consruction of overexpression and knockdown of mir-30 b in chicken myocardial cells,we treated the cells with H2O2 and NAC. The results show that after knockdowning of mir-30 b in myocardial cell, we found the levels of ROS, myocardial apoptosis rate and the expression of Caspase-3 and Bax decreased, while Bcl-2 expression increased, compared with normal group in a significant difference(P < 0.05). There were opposite results in overexpression of mir-30 b myocardial cells. The results show that mir-30 b which can inhibit Oxr1 expression causes myocardial cell apoptosis induced by oxidative stress.To sum up, low selenium diet can cause mir-30 b, Caspase-3 and Bax increased, and Oxr1, Bcl-2 decreased, which lead to myocardial tissue oxidative stress and cell apoptosis. In vitro we confirmed that Oxr1 is a target gene for mir-30 b, which can inhibit Oxr1 expression. Overexpression of mir-30 b in myocardial cells could increase ROS level and cell apoptosis, the expression of Caspase-3 and Bax, while the expression of Oxr1 and Bcl-2 decreased. The results show that low selenium diet can cause myocardial tissue mir-30 b expression decreased which could inhibit Oxr1, and cause myocardial cell apoptosis induced by oxidative stress.