Fig. 3: Olfactory marker protein (OMP) knockdown alters the cAMP response, resulting in decreased glucagon secretion at high glucose concentrations.

a, b qRT-PCR analysis of a Omp expression and b proglucagon (Gcg) expression after transfection with Omp-specific siRNA in αTC1.9 cells. c Analysis of secreted glucagon levels in conditioned medium of transfected αTC1.9 cells with different concentrations of glucose. d–g Intracellular cAMP levels were analyzed with the indicated glucose concentration for 15 min in αTC1.9 cells transfected with siNEG or siOMP. *p < 0.05, siNEG 5 mM glucose vs. siNEG 30 mM glucose, #p < 0.05, siOMP 5 mM glucose vs. siOMP 30 mM glucose, $p < 0.05, siNEG 5 mM glucose vs. siOMP 5 mM glucose, §p < 0.05, siNEG 30 mM glucose vs. siOMP 30 mM glucose. h CREB phosphorylation was analyzed using western blotting after 15 min of incubation of transfected cells with the indicated glucose concentrations. i After transfection, αTC1.9 cell survival was assessed using the MTS assay at the indicated time points. The two-tailed Student’s t-test was used to determine statistical significance. Error bars indicate the standard deviations. *p < 0.05, vs. 5 mM glucose, #p < 0.05, ##p < 0.01 vs. siScramble at each glucose concentration.