Treatment of type 2 diabetes by adenoviral-mediated overexpression of the glucokinase regulatory protein

The enzyme glucokinase (GK) plays a central role in glucose homeostasis. He patic GK activity is acutely controlled by the action of the GK regulatory protein (GKRP). In vitro evidence suggests that GKRP reversibly binds to GK and inhibits its activity; however, less is known about the in vivo functi on of GKRP. To further explore the physiological role of GKRP in vivo, we u sed an E1/E2a/E3-deficient adenoviral vector containing the cDNA encoding h uman GKRP (Av3hGKRP). High fat diet-induced diabetic mice were administered Av3hGKRP or a control vector lacking a transgene (Av3Null). Surprisingly, the Av3hGKRP-treated mice showed a significant improvement in glucose toler ance and had lower fasting blood glucose levels than Av3Null-treated mice. A coincident decrease in insulin levels indicated that the Av3hGKRP-treated mice had sharply improved insulin sensitivity. These mice also exhibited l ower leptin levels, reduced body weight, and decreased liver GK activity. I n vitro experiments indicated that GKRP was able to increase both GK protei n and enzymatic activity levels, suggesting that another role for GKRP is t o stabilize and/or protect GK. These data are the first to indicate the abi lity of GKRP to treat type 2 diabetes and therefore have significant implic ations for future therapies of this disease.