Glucose-responsive artificial promoter-mediated insulin gene transfer improves glucose control in diabetic mice

Figure 1 rAd-SP-rINSfur administration reduces high blood glucose levels to normal physiological range in Lepr^db/db mice. A: Schematic diagram of adenoviral construct expressing furin cleavable insulin gene under the control of synthetic promoter. The synthetic promoter is composed of nine transcription factor binding elements upstream of pyruvate kinase basal promoter (L-PK). A furin-cleavable site was introduced at the junction of the B-chain and C-peptide; B: Blood glucose levels; C: Body weights of Lepr^db/db mice treated with rAd-CMV-βgal or rAd-SP-rINSfur. Viruses were injected into experimental animals at 12 wk of age with a dose of 3 × 10¹⁰ viral particles, and blood glucose levels and body weights were monitored. Blood glucose levels and body weights were measured between 2-4 pm during the day, and food and water were given ad libitum during the experiments. All values are mean ± SE. Day 0 indicates the day of viral injection. HNF-1: Hepatocyte nuclear factor-1; C/EBP: CCAAT enhancer binding protein; GlRE: Glucose responsive elements; HNF-4: Hepatocyte nuclear factor-4.

Figure 2 rAd-SP-rINSfur administration improves glucose tolerance in Lepr^db/db mice. Glucose (2 g/kg body weight) was administered by intraperitoneal injection, and blood glucose levels were measured at (A) 4 wk and (B) 6 wk (n = 4-6) after virus injection. The area under the curve (AUC) for each glucose tolerance test was quantified. All values are mean ± SE. ^bP < 0.01 vs rAd-CMV-βgal group.

Figure 3 rAd-SP-rINSfur administration improves insulin tolerance in Lepr^db/db mice. Insulin (1.5 U/kg body weight, ip) was administered to mice injected with rAd-CMV-βgal or rAd-SP-rINSfur at 5 wk after virus injection (n = 4-6), and blood glucose levels were measured. The area under the curve (AUC) for each insulin tolerance test was quantified. All values are mean ± SE. ^aP < 0.05 vs rAd-CMV-βgal group.

Figure 4 rAd-SP-rINSfur administration preserves endogenous islets in Lepr^db/db mice. Pancreatic samples were obtained from rAd-CMV-βgal and rAd-SP-rINSfur virus-treated animals on day 50 after virus injection. Tissue sections were prepared and stained with hematoxylin and eosin (HE) or stained with anti-insulin antibody. (A) is 20 × and (B) is 40 × magnification.