Division of Endocrinology and Metabolism, Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA.
Mol Metab. 2014 Nov 1;4(1):70-6. doi: 10.1016/j.molmet.2014.10.005. eCollection 2015 Jan.
Type 1 diabetes results from autoimmune destruction of beta-cells in the pancreas. Our objective is to reconstitute a glucose-responsive system in the liver to regulate hepatic insulin production for improving glycemic control in type 1 diabetes.
We have cloned the glucose-responsive element (GRE) from the promoter of acetyl-CoA carboxylase (ACC), an enzyme that catalyzes the rate-limiting step in fatty acid synthesis in the liver in response to glucose. To increase the amplitude of glucose induction, we quadruplicated the GRE DNA by gene duplication. The resulting GRE multimer (4×GRE) was tested for its ability to drive rat proinsulin cDNA expression in hepatocytes and insulin-deficient diabetic mice.
We showed that this GRE multimer-directed glucose-responsive system produced insulin in hepatocytes in a glucose-dependent manner. When delivered into the liver by adenovirus-mediated gene transfer, this glucose-responsive insulin production system was able to reverse hyperglycemia to a normal range without causing hypoglycemia after glucose challenge or overnight fasting. Insulin vector-treated diabetic mice exhibited significantly improved blood glucose profiles in response to glucose tolerance, correlating with insulin production in the liver. We recapitulated these findings in streptozotocin-induced diabetic CD1 mice and autoimmune non-obese diabetic mice.
Our data characterized the GRE motif from the ACC promoter as a potent glucose-responsive element, and provided proof-of-concept that the 4×GRE-mediated hepatic insulin production is capable of correcting insulin deficiency and improving glycemic control in type 1 diabetes.
1 型糖尿病是由胰腺β细胞的自身免疫性破坏引起的。我们的目标是在肝脏中重建一个葡萄糖反应系统，以调节肝胰岛素的产生，从而改善 1 型糖尿病的血糖控制。
我们已经从乙酰辅酶 A 羧化酶（ACC）启动子中克隆了葡萄糖反应元件（GRE），该酶在肝脏中催化脂肪酸合成的限速步骤，以响应葡萄糖。为了增加葡萄糖诱导的幅度，我们通过基因复制将 GRE DNA 四倍化。所得的 GRE 多聚体（4×GRE）被测试其在肝细胞和胰岛素缺乏的糖尿病小鼠中驱动大鼠胰岛素原 cDNA 表达的能力。
我们表明，这种 GRE 多聚体指导的葡萄糖反应系统以葡萄糖依赖的方式在肝细胞中产生胰岛素。当通过腺病毒介导的基因转移递送到肝脏中时，这种葡萄糖反应性胰岛素产生系统能够将高血糖逆转到正常范围，而不会在葡萄糖挑战或 overnight fasting 后引起低血糖。胰岛素载体治疗的糖尿病小鼠在葡萄糖耐量方面表现出显著改善的血糖谱，与肝脏中的胰岛素产生相关。我们在链脲佐菌素诱导的糖尿病 CD1 小鼠和自身免疫性非肥胖型糖尿病小鼠中重现了这些发现。
我们的数据将 ACC 启动子中的 GRE 基序表征为一种有效的葡萄糖反应元件，并提供了概念验证，即 4×GRE 介导的肝胰岛素产生能够纠正 1 型糖尿病的胰岛素缺乏并改善血糖控制。
