FIGURE 4.

Increased FoxO1 activation reduces cell size and induces autophagy in cardiomyocytes. Cardiomyocytes were infected with WT-FoxO1, CA-FoxO1, or β-galactosidase adenovirus for 24 h and immunostained with sarcomeric α-actinin (green) and To-Pro3 nuclear stain (blue). A–C, infection of cardiomyocytes with either WT-FoxO1 (B) or CA-FoxO1 adenovirus (C) results in decreased cell size compared with β-galactosidase-infected cells (βgal) (A). Arrows indicate representative cardiomyocytes from each treated group. D, quantitative analysis indicates significant reduction (>30%) in WT-FoxO1 and CA-FoxO1-infected cardiomyocyte cell size compared with β-galactosidase-infected cardiomyocytes. E–I, Ad-GFP-LC3-infected cardiomyocytes were co-infected with β-galactosidase, WT-FoxO1, CA-FoxO1, WT-FoxO3, or CA-FoxO3 adenovirus. Increased in GFP-LC3 puncta are apparent compared with β-galactosidase-infected cardiomyocytes (E–I, arrows). J, quantitative analysis indicates a significant increase in the percentage of cells expressing more than five GFP-LC3 puncta in FoxO-infected cardiomyocytes compared with β-galactosidase-infected cardiomyocytes. Significance (*) was determined by one-way analysis of variance (p < 0.05; n = 3).