Suppression of the Nuclear Factor Eny2 Increases Insulin Secretion in Poorly Functioning INS-1E Insulinoma Cells
Figure 4
Insulin secretion in response to exendin-4 and forskolin after Eny2 knockdown: levels of cAMP. (a, b) INS-1E cells were stimulated with 50 nmol/l exendin-4 72 hours after transfection with either control or two different Eny2-specific siRNAs. Insulin secretion in response to exendin-4 was augmented by the two specific siRNAs, both in absolute (a) and relative terms (b) (). (c) Insulin secretion after stimulation with 50 nmol/l exendin-4 and 10 μmol/l forskolin, which led to comparable secretory responses. (d) INS-1E cells were stimulated with different concentrations of exendin-4 for 5 minutes. The concentration of cellular cAMP was measured by a competitive ELISA. (e, f) Time course of cellular cAMP levels after stimulation with 50 nmol/l exendin-4 in absence (e) and presence (f) of 100 μmol/l IBMX. In both setups the knockdown of Eny2 did not affect cellular cAMP levels. *, **, ***; one way ANOVA with posttests and unpaired -test.
