Figure 2.

Effects of oxidative stress in β cell neogenesis. (a) An overview of the ROS expression levels at distinct stages of β cell development in mouse embryo. The presence of ROS (E12.5–E17.5) largely overlaps with the Ngn3 expression period (E14–E18.5). (b) Schematic diagram of effects of ROS on β cell neogenesis. On the one hand, hypoxia as an important inducer of ROS activates HIF-1α which suppresses Ngn3 expression, which results in impaired β cell neogenesis. On the other hand, ROS directly upregulates Ngn3 and Pdx-1 in β cell development, and NADPH oxidase seems to be a crucial source of ROS in this process, leading to increased β cell neogenesis.