Figure 4
From: PERK eIF2 alpha kinase is required to regulate the viability of the exocrine pancreas in mice
Secretion is normal in exPKO acinar cells. (A) Amylase secretion. The fraction of secreted amylase to total cellular amylase content was measured enzymatically for both basal and carbachol-stimulated pancreatic lobules. This is a representative result from 4 independent experiments. Lobules were isolated from P17 β-Perk; Perk+/+ (WT) and β-Perk; Perk-/- (PKO). The β-Perk; Perk-/-(PKO) mice are rescued for Perk in endocrine β-cells with all other tissues remaining PERK-deficient, whereas the β-Perk; Perk+/+ (WT) control mice harbor the rescuing Perk transgene in an otherwise WT background. The β-Perk; Perk-/- (PKO) mice are analogous to the exPKO mice with respect to their exocrine pancreas. Each data point represents three replicate samples. (B) Pulse-chase analysis of protein secretion. The average of two independent experiments is shown. Lobules were isolated from exPKO (PKO) and wild-type (WT) littermates (P17-18). Lobules were labeled with [35S]Met/Cys as described in Figure 3 and then chased in "cold" media over 2 hours. The fraction of TCA-precipitable radioactivity in the media to total cellular TCA-precipitable counts was calculated for each time point for both "basal," (without a secretagogues) and secretagogues-stimulated conditions ("Cch"; with 0.5 μM carbachol).