154. Small Inhibitory RNA Expressed from Sleeping Beauty Transposons Can Reduce alpha1-Antitrypsin Expression

Abstract

Type 1 diabetes patients depend upon insulin replacement therapy. However, glycemic control is not always achieved and the resulting chronic hyperglycemia leads to microvascular, macrovascular and neurological complications. Therefore, there is a need for new treatment strategies for diabetes mellitus that would permit tight glucose regulation. Transgenic mice expressing insulin in skeletal muscle counteract type 1 diabetic alterations which indicates that muscle cells constitutively secreting low insulin levels could be used in gene therapy for diabetes. Furthermore, expression of glucokinase in skeletal muscle of transgenic mice reduced diabetic hyperglycemia without inducing hypoglycemia. However neither of these two transgenic mice showed complete reversion of the diabetic phenotype. Here, we examined the effect of co-expression of insulin and glucokinase in skeletal muscle on diabetic alterations and glycemia. Double transgenic mice expressing both insulin and glucokinase in skeletal muscle and skeletal muscle from diabetic mice electrotransferred with insulin and glucokinase genes were obtained. Blood glucose levels, skeletal muscle glucose uptake, glucose tolerance and insulin sensitivity were analyzed after streptozotozin (Stz) treatment. Double transgenic and electrotransferred mice counteracted hyperglycemia and restored fluid and food intake after treatment with Stz. In contrast, control mice presented polydipsia and polyphagia and developed severe diabetes. No hypogluycemia was detected in the Stz-treated mice expressing both insulin and glucokinase genes. In addition, these mice normalised both hepatic and skeletal muscle glucose metabolism and showed increased glucose disposal after an intraperitoneal glucose tolerance test. These results suggest that secretion of basal levels of insulin, in conjunction with increased glucose uptake by the skeletal muscle, might permit tight regulation of glycemia. Insulin and glucokinase genes cooperated by increasing glucose transport into the muscle cell and phosphorylation. Thus, this study provides evidence of a feasible non-viral gene therapy approach for type 1 diabetes involving the cooperative action of two genes, glucokinase and insulin, which leads to tight regulation of glucose homeostasis.