Figure 2.

Nrf2 is necessary for HFD-adaptive β-cell proliferation in vivo. A and B: C57BL/6 mice were fed an HFD or RD for 1 week, after which their pancreata were removed, embedded, and immunolabeled with insulin and Nrf2 antibodies (inset magnification 3.5×). Percentage of Nrf2- and insulin-positive cells was calculated. C: Pancreata from C57BL/6 mice fed an RD or HFD for 1 week were immunolabeled with insulin and Nqo1 antibodies. D: MIP-CreER^TAM/Nrf2^lox/lox mice were crossed to generate βNrf2KO mice, which were injected daily for 5 days with Tam or vehicle (Veh) (corn oil), followed by 5 days of recovery and 1-week feeding with HFD or RD. E and F: Pancreata from βNrf2KO mice fed an HFD for 1 week immunolabeled with insulin and Nrf2 antibodies (inset magnification 7.5x). Percentage of Nrf2- and insulin-positive cells was calculated. G and H: Islet protein extracts from βNrf2KO mice fed an HFD for 1 week were immunoblotted against Nrf2 and actin antibodies. Nrf2 levels were then quantified using densitometry. I and J: Pancreata from βNrf2KO mice fed an RD or HFD for 1 week were immunolabeled with insulin and Ki67 antibodies. Percentage of proliferation in insulin-positive cells was then calculated. K: Pancreata from βNrf2KO mice fed an HFD or RD for 1 week were immunolabeled with insulin. L: Islets from βNrf2KO mice fed an RD or HFD for 1 week were assayed for insulin content normalized to DNA content. M: Islets were isolated from βNrf2KO mice fed an HFD or RD for 1 week, RNA was extracted, and expression of β-cell identity genes was measured. N and O: Pancreata from βNrf2KO mice fed an HFD for 1 week were immunolabeled with insulin and Pdx1 antibodies. Percentage of Pdx1 nuclear-positive/insulin-positive cells was calculated. Data are mean ± SEM. *P < 0.05, **P < 0.005, ***P < 0.0005, ****P < 0.0001.