Protein phosphatase 2A impairs cardiac uptake of glucose in the mammalian heart

Fig. 1. Bar diagram showing gene expression (ordinate) of PP2A (Ppp2ca gene) in the mouse ventricles of PP2A-TG (n = 16) and WT (n = 7). Data are presented as NRQ ± SD; *P < 0.05 vs WT, (NRQ; normalized relative quantity). Groups labelling: WT – wild type mice, PP2A-TG – mice with overexpression of the catalytic subunit α of protein phosphatase 2A

Fig. 2. PET. Uptake of [18F]FDG into the myocardium of WT and PP2A.±. A Exemplary images of a static PET of the long axis (HLA) and short axis (HSA) of the heart 45 min after intraperitoneal radiotracer injection (6.2 to 12.0 MBq). B Activity concentration in standardised uptake values (SUV ± SD). C SUVgluc (https://doi.org/10.1016/j.nucmedbio.2025.109095) in myocardium of WT (n = 5) and PP2A ± (n = 8)

Fig. 3. Western blot analysis of proteins of the insulin receptor downstream pathway in the heart of WT and PP2A-TG mice with representative immunoblots. AKT phosphorylation was calculated as the pAKT and AKT expression ratio. The resulting value 0.1 > P > 0.05 is a statistical trend and is considered as a non-significant change. Data are presented as mean ± SD; n = 7–12 per group; *P < 0.05 vs CON. For groups labelling, see Fig. 1. Full-length blots are presented in Supplementary Figs. 1,2,5 and 6

Fig. 4. Western blot analysis of phosphorylated and non-phosphorylated PFKFB2 protein in the heart of WT and PP2A-TG mice with representative immunoblots. Data are presented as mean ± SD; n = 6–12

Fig. 5. A Western blot analysis of glycogen metabolism-related proteins in the heart of WT and PP2A-TG mice with representative immunoblots. GSKβ phosphorylation was calculated as the pGSKβ and GSKβ expression ratio. Full-length blots are presented in Supplementary Figs. 3, 4 and 7 (B) Glycogen content in the heart of WT and PP2A-TG mice. Data are presented as mean ± SD; n = 7–12 per group; *P < 0.05 vs CON. For groups labelling, see Fig. 1

Fig. 6. The scheme of intracellular insulin receptor pathway (Arneth et al. 2019; Umbarkar et al. 2023). Red arrows indicate the direction of the observed expression changes in proteins involved in glucose metabolism and regulation. AKT: Akt serine/threonine kinase; AMPK: AMP-activated; GLUT1, 4: glucose transporter 1, 4; Gsk3b: glycogen synthase kinase 3 beta; GYS: glycogen synthase; IRS: insulin receptor substrate; mTOR: mechanistic target of rapamycin kinase; PI3K: phosphatidylinositol-4,5-bisphosphate 3-kinase; PP: protein phosphatases; PYG: glycogen phosphorylase