| Type I diabetes, also known as insulin-dependent diabetes mellitus, is the result of insulin deficiency caused by the autoimmune destruction of the insulin-producing pancreatic β-cells and characterized by hyperglycermia and ketoacidosis. During the past twenty years, the morbidity of diabetes mellitus has been rising and it has become the third major noninfectious disease next to malignant tumors, cerebrovascular and cardiovascular diseases in China. Now the possible methods to treat type I diabetes are: insulin injection; pancreas or islet transplantation. The conventional insulin therapy dose not provide adequate glycemic control in type I diabetic patients, nor prevents the development of long-term diabetic complications. The diabetic patients suffer from the twice insulin injections daily and their life quality is lower. Pancreas or islet transplantation is considered a curative treatment for type I diabetes. But the major limitations of these protocol are the scarcity of donor, autoimmune reaction, the low survival rate of the donor and the high cost, which prevent the widespread applications to a large type I diabetic patients population. Gene therapy means to deliver some therapeutic genes into the patients' body by the use of a vector and those genes will be expressed into functional proteins the patients lost and the disease will be cured. One hopeful treatment for type I diabetes is insulin gene therapy. It means the development of β-cells substitutes by introducing an insulin-producing gene into non β-cells, which would evade the β-cells specific autoimmune attack. And a successful insulin gene therapy system should comprise at least the following important components: 1. an effective insulin gene transfer system; 2. a regulatory system that regulates insulin levels within extremely narrow physiological limits in response to glucose; 3. an appropriate target cell that has biochemical characteristics similar to β-cells but is not a target for autoimmune attack; 4. the biochemical machinery for the processing of proinsulin into mature, active insulin in the target cell. Based on the previous study on obtaining the mutated human proinsulin cDNA, which contains furin consensus cleavage sequences and allows the non-β cell to secret mature insulin, we have been studying the glucose regulation of the Acetyl-CoA carboxylase promoter PI (ACC PI). We also have been considering the combined effects of the phage ΦC31 integrase and the rapid tail-vein injection on the treatment of the type I diabetes.The glucose regulation of the ACC PI promoterAcetyl-CoA carboxylase (ACC) is the rate-limiting enzyme for long-chain fatty acid synthesis. The ACC PI promoter has a tissue-specific manner distribution and the glucose response ability. We obtained the rat ACC PI promoter sequence by PCR, then constructed plasmids pACC-GFP and pACC-mhINS with the promoter to express the GFP and the mutated human insulin (mhINS), respectively. After these plasmids were transfected into the L02 cells, the GFP and mhINS levels were tested under different glucose concentrations in the culture medium. The results showed that the ACC PI promoter could really drive the expression of the target genes in the L02 cells, and the glucose concentrations regulated the genes' expression. The quantity of human insulin in cells with high glucose increase 2.89 folds compared with the low glucose. These results suggested that the ACC PI promoter could be a useful element in the diabetes gene therapy. The study on type I diabetes mediated by the phage ΦC31 integrase Hydrodynamic based procedure has been proved to improve greatly the efficiency of gene delivery. It can be very efficient for naked DNA transfer to the mouse liver. The liver is the ideal target organ for gene therapy. The site-specific integrase system--ΦC31 can mediate the foreign DNA integrate into the host's chromosome and can prolong the expression of the foreign gene. The engineered insulin cDNA was inserted into an expression vectors under the control of CMV pro...
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