Fig. 1

Specific localization of GRK2 in the pancreatic islet and expression levels of GRK2 protein in the pancreas of WT and GRK2+/− mice. Representative photomicrographs showing the immunohistochemical staining of serial pancreatic sections using antibodies against GRK2 or insulin as an islet marker, counterstained with hematoxylin (magnification × 40; scale bar 0.2 mm). Incubations without primary antibody are performed as a negative control (a). Whole pancreatic tissue lysates, WT n = 5, GRK2+/− n = 5 (b) or isolated islets lysates, WT n = 5, GRK2+/− n = 7 (c) were subjected to Western blot analysis and probed with antibodies against GRK2 and β-actin. Stereological analysis of the pancreas analyzing three pancreatic sections separated 0.4 mm (each whole section was imaged, with an average 30 islets detected per section: total 565 islets were counted in WT mice (average of 94 islets/mice in three sections) and 407 islets in GRK2+/− mice (average of 101 islets/mice in three sections), non statistically different by t test), islet mass was quantified measuring insulin-positive area in WT n = 6 and GRK2+/− n = 4 (d). Number of isolated islets per digested pancreas, WT n = 17, GRK2+/− n = 20 (e). Total pancreatic insulin content measured in acidic-extracts of pancreata by ELISA, WT n = 6 GRK2+/− n = 5 (f). Means ± SEM data are represented, statistical analysis was performed using unpaired t test. *p < 0.05, **p<0.01