Figure 5.

SENP1 amplification of β-cells is redox-dependent. (A) Mouse β-cells, infected with adenovirus expressing GFP (Ad-GFP) or SENP1 (Ad-SENP1, which co-expresses GFP), were maintained in non-stimulatory glucose (1 mM) for 2 hours prior to whole-cell patch-clamp. In some experiments, H₂O₂ (200 µM) was infused directly into cells at the time of the experiment; (B) Immunoblotting of protein lysates from INS-1 832/13 cells demonstrates the up-regulation of monomeric SENP1 (with Ad-SENP1) and its subsequent dimerization in the presence of H₂O₂ (200 µM); (C,D) Over-expression of SENP1 recapitulates the effect of NADPH to amplify β-cell exocytosis (C), an effect that is lost under oxidizing conditions (D). * p < 0.05 compared with Ad-GFP.