Up-regulating autophagy by targeting the mTOR-4EBP1 pathway: a possible mechanism for improving cardiac function in mice with experimental dilated cardiomyopathy

Fig. 1. Modulating autophagy and cardiac matrix remodeling of DCM. (A) Picrosirius red staining indicated significantly changes of collagen distribution in the four different groups. (B) Histochemical analysis showed that there was a significant increase of collagen distribution in the DCM group compared with the control group. Quantitative assessment demonstrated that the CVF was significantly decreased in the rapamycin group, and it was increased in the 3-MA group compared with the DCM group. †††P < 0.001 vs Control, **P < 0.01 and #P < 0.05 vs DCM. Scale bar = 100 μm

Fig. 2. Transmission electron microscopy assessment for modulating autophagy. (A) Transmission electron microscopy indicated significant changes of autophagosomes in the four different groups. (B) Transmission electron microscopy showed that there was a significant increase of autophagosomes in the DCM group compared with the control group. Quantitative assessment demonstrated that autophagosomes were significantly increased in the rapamycin group, and they were decreased in the 3-MA group compared with the DCM group. †††P < 0.001 vs Control, ***P < 0.01 and #P < 0.05 vs DCM. The arrows indicated the double membrane autophagosomes in the different groups

Fig. 3. Modulating autophagy and the mTOR-4EBP1 pathway. a-d The expression levels of p-mTOR and p-4EBP1 were significantly decreased in rapamycin-induced autophagy activation, and the effects were significantly increased by down-regulating autophagy with 3-MA. The increased expression of LC3 II indicated the activation of autophagy in the rapamycin group, whereas the expression of LC3 II was decreased in the 3-MA group. ††P < 0.01 vs Control, **P < 0.01, *P < 0.05, ##P < 0.01, and #P < 0.05 vs DCM. Each experiment was conducted 3 times in triplicate

Fig. 4. M-mode ultrasound images at the level of papillary muscles in the long-axis view. The M-mode echocardiography evaluation included the following four experimental groups as follows: control group, DCM group, rapamycin group, and 3-MA group. The red lines and blue lines indicated the LVEDD and LVESD respectively. Each group, n = 8

Fig. 5. Modulating autophagy and cardiac function. (A) and (B) Cardiac function differed in the four groups, and the LVEF and FS significantly improved in the rapamycin group compared with the DCM group. (C) and (D) The LVEDD and LVEDV were significantly decreased in the 3-MA group compared with the DCM group. ††P < 0.01 and †P < 0.05 vs Control, **P < 0.01, *P < 0.05, and #P < 0.05 vs DCM. Each group, n = 8