The Effect Of Extl3 On Type 1 Diabetes And Its Possible Mechnism

Part Ⅰ The development trend of type 1 diabetes after pancreatic islet targeted down-regulation of Extl3 expressionObjcetive Type 1 diabetes(T1DM)is a chronic disease characterized by elevated blood glucose levels due to insulin deficiency by destruction of islet β cells.Therefore,the destruction of islet β cells caused by various reasons can aggravate the progression of T1 DM.Extl3 is a member of the EXT family,mainly involved in the synthesis of the HS chain and functions as a receptor for the Reg protein.Studies have shown that Extl3 is associated with a variety of diseases such as nerves,immunity,bones,tumors and other tissues.In the pancreas,Extl3 also plays an important role.Studies have reported that Extl3 is expressed in pancreatic islets,and the absence of Extl3 in pancreatic islets can lead to abnormal pancreatic islet morphology,β cell dysfunction and abnormal blood glucose.However,in T1 DM,the expression and impact of Extl3 are not yet clear.Therefore,this study aims to explore the role of Extl3 in the development of type 1 diabetes,its impact on islet morphology and insulin secretion,and explore related mechanisms.Methods At the animal level,by interfering with the expression of Extl3 in the pancreas of T1 DM mice,the effect of Extl3 knockdown on the metabolic phenotype,islet morphology,and insulin secretion in mice was studied and related mechanisms were explored.C57 BL / 6J mice were randomly divided into Con-sh RNA + STZ group and Extl3-sh RNA + STZ group.The two groups of mice were usd pancreatic ductal infusion of corresponding AAV8 and observed for three weeks.Body weight and fasting blood glucose were monitored weekly.Three weeks after the operation,both groups underwent STZ(40mg / kg)intraperitoneal injection modeling once a day for five consecutive days.Weekly monitoring of body weight and fasting blood glucose values,the sixth week of sacrifice,fasting blood was retained.Enzyme-linked immunosorbent assay was used to determine the level of serum insulin in mice;hematoxylin-eosin staining was used to observe the pathological changes of mouse pancreas and count the number of islets and islets;the expression of Extl3 in mouse pancreas was detected by immunohistochemistry and immunofluorescence.Results 1.In the normal pancreas,Extl3 is expressed in the islets of the pancreatic endocrine part.2.After pancreatic ductal infusion surgery and STZ modeling,the body weight of the two groups of mice showed a brief decrease process,and there was no significant difference between the two groups.3.After 6 weeks of modeling,the fasting blood glucose of both groups of mice was significantly increased,suggesting that the type 1 diabetes model was successfully modeled.Compared with the control group,the experimental group had higher fasting glucose(13.10 ± 4.732 vs.21.40 ± 1.389 mmol / L,P = 0.0435),and the serum insulin concentration in the experimental group decreased(0.482 ± 0.109 vs.0.300 ± 0.019 ng / m L,P = 0.039),suggesting that islet function is impaired.4.HE staining and pancreatic islet count results suggest that there is no significant difference in the number of pancreatic islets and islet area between the two groups.Conclusion At the animal level,it was found that knocking down the expression of Extl3 in β cells of the islets can aggravate the destruction of islets of T1 DM mice,induce an increase in blood glucose,and promote the development of T1 DM.This study hopes to provide ideas for elucidating the pathogenesis and prevention of T1 DM.Part Ⅱ The effect of Extl3 on the function of pancreatic islet β cells and its mechanismObjcetive This study first observed the increase of fasting blood glucose and the decrease of serum fasting insulin in T1 DM mice after downregulation of Extl3 in animal models.In pancreatic islets,βcells secrete insulin and play a role in reducing blood glucose.In this study,the effect of Extl3 on insulin secretion of pancreatic islet cells was verified by the mouse islet cell line MIN6 cells.Methods RNA level and protein level verified the interference effect of Extl3-si RNA;transfected MIN6 cells with si-RNA technology to reduce the expression of Extl3 in the cells.After 48 hours of culture,the cells were harvested to detect the GSIS function of the two groups of MIN6 cells.The overexpression of Extl3 plasmid was constructed,and the effect of overexpression of Extl3 plasmid was verified at the RNA level and protein level;the overexpression plasmid was transfected into MIN6 cells to increase the expression of Extl3 in the cells,and the cell function was harvested after36 hours.Results1.RNA levels and protein levels suggest that the expression of Extl3 in pancreatic islet β cells is reduced after si RNA transfection.GSIS experimental results show that compared with the control group,inhibition of Extl3 expression can impair the insulin secretion ability of MIN6 cells under high glucose stimulation(2.445 ± 0.625 vs.1.398 ± 0.205,P = 0.0030).2.RNA levels and protein levels suggest that the expression of Extl3 in MIN6 cells increased after overexpression of Extl3.The GSIS test results showed that compared with the control group,there was no significant change in the function of MIN6 cells after enhanced Extl3 expression.Conclusion Decreasing the level of Extl3 in pancreatic islet β cells can impair the ability of high glucose to stimulate islet beta cells to release insulin,but after overexpressing Extl3,the ability of high glucose to stimulate islet β cells to release insulin has no obvious effect.