| Diabetes can be divided into two different types according to their different pathogenesis and clinical characteristics, they are the type 1 and the type 2. The type 1 diabetes mellitus usually occur in people under 30, especially in the teenagers. This kind of diabetes is usually onset acutely and often results in ketoacidosis. This type diabetes is also known as insulin-dependent diabetes mellitus, referring to depending on the long-term supplement of exogenous insulin which could help to maintain the body metabolism. The cause of this diabetes mellitus mostly is for the ? cells being damaged by virus,high glucose,high fat or autoimmune inflammation etc, and resulting the decreasing of insulin. So concerning about this type of diabetes,if we can protect the cell from being damaged, we can alleviate the disease. This type of diabetes is usually called non-insulin dependent diabetes, often occur in the people after age of 40, especially in the middle-aged and the elder, it usually appears slowly. For this type of diabetes mellitus, plasma insulin levels can be normal or even higher than that of the normal, and mostly with insulin resistance, for the reducing capacity of consuming glucose of the peripheral tissue, at last resulting high blood sugar. As we all know the balance of the body's blood sugar benefits from maintaining blood sugar production and consuming in dynamic equilibrium. The liver is a vital organ of the sugar metabolism, especially under the condition of fasting, liver gluconeogenesis become the main source of blood sugar, but the excessive activation of gluconeogenesis is the main cause of abnormal high blood glucose. And the insulin secreted from pancreatic beta cells promotes peripheral tissue to use sugar, keeping the balance of blood sugar, which is vital to the body. Once any one of each aspect is dysfunction it will lead to glucose metabolic disorder, either for the increasing of sugar production, or the decline of sugar using, at last facilitate blood sugar rise, and lead to the occurrence of diabetes.Liver gluconeogenesis is strongly active under fasting condition, in order to increase glycogen output(HGP) and meet the sugar needs of the body. Gluconeogenesis is also very active in diabetic mouse. And a large number of studies demonstrated that fork transcription factor 1(FoxO1) protein was increased either in the liver of either hungry mice or diabetic mice. In normal mice liver cell line TAMH, FoxO1 is high expression induced by glucocorticoid or the activator of adenylate cyclase such as forskolin, and activate a series of gluconeogenesis key enzyme such as PEPCK and G6 Pase, resulting the increase of HGP. Studies have showed that cancer or glucose metabolic disorder can dysregulate the expression profile of many different kinds of microRNA including microRNA-9(miR-9) ? microRNA-29(miR-29),which can further accelerate tumour progression and disturbance of carbohydrate metabolism. A large number of studies have shown that fork(FoxO) family of transcription factors are the target of the miRNA. In endometrial carcinoma, it is also found that the high expression of miR-9 suppressed the tumor suppressor FoxO1 expression, triggering a series of Pathological physiology changes and leading to the occurrence of cancer. While another study found that miR-29 was high expression in diabetic mice, which can restrain the protein expression of liver gluconeogenesis key enzyme and transcription activation key enzymes pgc-1 alpha, thus lower fasting blood glucose levels. So in the metabolic disorders conditions whether the low expression of miR-9 in the liver has something to do with the high expression of transcription factor FoxO1, its molecular mechanism is unclear.In the first part of this study, we utilized normal mice liver cell line TAMH, the fasting mice model, the diet induced obese mice model and the diabetic mice model to research and analyze. We examined the expression of the relative RNA and miR-9 of the mice liver tissue and TAMH cells, and the protein level of the transcription factor FoxO1 and its target genes expression level of PEPCK and G6 Pase.We demonstrated that the level of miR-9 in the liver of the fasting model mice is notable lower compared with the control feeding normal mice and there is also obviously lower expression in the liver of obesity and diabetic mice. We also used computer software to predict the miR-9 binding site sequence in FoxO1 3'UTR, luciferase reporter gene assay also proved its relationship and function. The result of this study has identified that the expression of FoxO1 was partly depressed by miR-9, which inhibited the expression level of gluconeogenesis key enzymes, such as PEPCK and G6 Pase. We overexpressed TAMH cells with miR-9, stimulating the cell with forskolin, and found that FoxO1 protein expression significantly lowered compared with the control group, while the expression level of gluconeogenesis key enzymes such as PEPCK, G6 Pase obviously decreased, and cell supernatant of sugar output level also had a significant decline. At the same time, the expression levels of key enzyme PEPCK and G6 Pase also declined greatly, and the cells sugar output in the supernatant also had a significant decline.Insulin secreted from the ?cell promote the peripheral tissue to use sugar, it is also the only lowering blood sugar hormone in body and at the same time, insulin is anabolic hormones, and it can promote the synthesis of glycogen, fat, protein, facilitate the conversion of glucose to energy or other structural material, promote the metabolism of sugar. Insulin secretion by pancreatic beta cells, secretion adjustment by the endogenous or exogenous substances such as glucose, lactose, ribose, arginine, glucagon, but pancreatic beta cell being injury and its apoptosis is considered to be the main reasons of the lack of insulin secretion, its damage factor is various, such as virus, autoimmune, high sugar, palmitic acid, and inflammatory factor and so on, in these control agent, IL-1,s effect to the damage of beta cell attract more and more attention.Artesunate(ART) is a kind of artemisinin derivatives, purified from the traditional Chinese medicine, can act as antiviral, anti-inflammatory and anti-cancer. ART has been known as the most effective and safe reagents to treat malarias for many years. But so far there is little report about its effect in treating diabetes. So in this study, we aim to explore whether ART could protect pancreatic beta-cell against cytokine-induced damage. We measured the production of nitrite(NO) with the Griess Assay Kit and determined the SIRT1 and inducible nitric oxide synthase(iNOS) expression with western blot. While the transcriptional activity of NF-?B was evaluated by luciferase reporter assay and the expression of Sirt1 was silenced by RNA interference. Additionally glucose-stimulates insulin secretion(GSIS) was performed to measure the effect of ART on pancreatic beta-cells function. The effect of ART on beta-cells viability and apoptosis was evaluated by using MTT assay and Hochest/PI staining, respectively.The result demonstrates that ART reversed the damage of pancreatic beta-cells induced by IL-1?, and ART inhibited IL-1?-induced activation of the NF-?B signaling pathway and iNOS expression and NO production in beta cells,and we also found that ART reversed the decrease of SIRT1 protein levels in IL-1?-treated INS-1 cells and islets,and we further testified that Inhibition of SIRT1 partially abolished the protective effect of ART on pancreatic beta-cells and SIRT1 was involved in the effect of ART on NF-?B signaling pathway in IL-1?-treated beta-cells by the way of SIRT siRNA and gene knockout,and at last we concluded that protection effect for IL-1?-treated beta-cells of ART was realised by activating SIRT protein expression, and use the SIRT to inhibit the action of the NF- kB signaling pathways. |
PDF Full Text Request