Epigenetic Study Of Genes Related To Hepatocyte Glucose Metabolism In Obese Rats

Background and AimsThe obese population all over the world has been doubled every 5 years. A third of the American people have over weigh problem, and 300,000 people die of obesity related disease directly or indirecrly. With the economic growth and living standard improves, the number of obesity in our country has increased rapidly, and people with obese related metabolic syndrome (diabetes, hypertension, hyperlipemia) are more popular.Metabolic syndrome is also called insulin resistance syndrome. It has become a global epidemic and a pulic health cirsis. Metabolic syndrome is characterized by glucose intolerant, insulin resistance, high TG, central obesity, etc. Patient with MS are usually fat than normal people.High calorie, high fat and immovable lifestyle are three major reasons for obesity. Dietary restraction and more sports are the critical measures to lose weight. Epigenetic modifications are influenced by environmental factors, whose slight change may impact the whole metabolic pathway. Some reports indicate that changes of nutritional environment result results in the changes of Epigenetcs. Thus, Epigenetcis and some acquired diseases are linked together. Liver is an important organ for metabolism, center for processing and distribution nutritions. It also play an important role in maintaing proper blood glucose, filter harmful substances form the blood. We analysis the epigenetic regulation of glucose metabolism related genes in high fat diet induced obese rat and normal rats as control, elucidate the molecular pathogenesis of diabetes and other metabolic syndrome. We also introduced a tranditional Chinese medicine, berberine to modify all the disorders caused by high fat diet, and try to elucidate the mechanism from the view of Epigenetics.Methods and results:1. The epigenetic study of obese rat hepatic glucose metabolism related genes.(1) Establisment of rat models: normal diet rats, high fat diet rats, high fat diet rats with BBR treatment. All the physiological index were detected, FBG of the three groups were all nomal, but high fat diet induced obese rats exerted a high inslulin level, indicating the relation between obesity and insulin resistance.(2) Determination of expression of hepatic glucose metabolism related genes. The expression level of Gck, LPK, Glut2, PFK1, PFK2 are lower in obese rats, while BBR treatment up regulate some of these genes expression.(3) Quantify of DNA methylation of interested genes of the three group rats. DNA methylation quantifying method established by Dr. Jiang MH was employed to detect the methylation level of interested genes. Hepatocyte genomic DNA was bisulfite treated before PCR plus sequencing. The methylation level was calculated by the height ratio of C vesus C plus T. The results indicate that methylation level of obese rats was up-regulated compared with normal ones, and BBR treatment can reduce the effect. Gene expression and DNA methyatlion stands a reverse correlation.2. Epigenetic study of insulin resistant hepatocytes induced by free fatty acids.We use two different hepatic cell models, BRL and L02, from rat and human respectively, to establish insulin resistant cell model, then conduct our study on the relation of epgeneitcs and insulin resistance.(1) Gene expression level of cell model. 0.1 mM PA was used to induced insulin resistance incuba with culture at least 24 hours. Vaired glucose consumption can be observed, and LPK, glut2, PFK expression were down regulated.(2) Detection of LPK promter methylation level in BRL/IR model. PA treatment resulted a up regulated methylation level , while BBR treatment reduced LPK methylation level.Conclusions:Obesity is the major reason for insulin resistance. Our research reveals its molecular mechanism from epigenetic view, especially promoter region methylation. We found a reverse correlation between LPK expression and promoter methylation, affecting the normal glysosis of liver. Higt fat diet result the accumulation of TG and other series of MS symptom. BBR can up regulate the expression of LPK, and reduce the methylation level might be a possible explanation for the cure effect of BBR. In conclusion, we explore the methylation mechanism of obese rats and insulin resistance cell model, and introduced BBR to modify the change. Our research provides new method to treat obese related MS, and new protection and treatment theory from the Epigenetic view.