Overexpression of decorin promoted angiogenesis in diabetic cardiomyopathy via IGF1R-AKT-VEGF signaling

Figures

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  Figure 1. Overexpression of decorin improved cardiac function in diabetic cardiomyopathy. (A) The oral glucose tolerance test (OGTT). (B) The left ventricular ejection fraction (EF) evaluated by echocardiography. (C) The fraction shortening (FS) evaluated by echocardiography. (D,E) The left ventricular wall thickness (including the interventricular septum (IVS) and the posterior wall (PW)) and the internal dimension of the left ventricle (LVID). (F–H) The hemodynamic function was evaluated by the cardiac catheter system, including the left ventricular end-diastolic pressure (LVEDP), as well as the Dp/dt maximum and minimum. All data are presented as the mean ± SEM. *p < 0.05; **p < 0.01.

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  Figure 2. Overexpression of decorin increased angiogenesis in the diabetic hearts. (A–C) The expression of decorin and VEGF. (D) The VEGF concentration in the plasma. (E) The capillary density using immunochemistry with a CD31 antibody. The photographs were taken at a magnification of 100× and zoomed at a magnification of 200×. The arrows show the capillary stained with the CD31 antibody. (F) The number of vessels counted from the immunochemistry staining. All data are presented as the mean ± SEM. *p < 0.05; **p < 0.01.

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  Figure 3. Overexpression of decorin ameliorated the angiogenesis impaired by high glucose (HG). (A–C) The expression of decorin and VEGF. (D,E) The tube formation test; the photographs were taken at a magnification of 100×. (F,G) The cell wound healing test; the photographs were taken in a magnification of 100×. (H,I) The apoptosis rate analyzed by an Annexin V–FITC kit through flow cytometry. (J) The proliferative ability assessed with a CCK8 assay. All data are presented as the mean ± SEM. *p < 0.05; **p < 0.01.

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  Figure 4. Overexpression of decorin activated the IGF1R-AKT-AP-1 pathway. (A,B) The phosphorylation of AKT was decreased by HG treatment in a time-dependent manner. (C–E) The expression of IGF1R, Bcl2, and Bax and the phosphorylation of AKT. (F,G) The phosphorylation of AP-1. All data are presented as the mean ± SEM. *p < 0.05; **p < 0.01. #p < 0.05, compared to Con. &p < 0.05, &&p < 0.01, compared to HG + GFP.

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  Figure 5. The AKT inhibitor MK2206 abolished the effects induced by overexpression of decorin. (A) The tube formation test; the photographs were taken at a magnification of 100×. (B) The cell wound healing test; the photographs were taken at a magnification of 100×. (C) The apoptosis assay. (D) CCK8 assessment. (E,F) The expression of VEGF, Bcl2, and Bax and the phosphorylation of AKT and AP 1. All data are presented as the mean ± SEM. *p < 0.05; **p < 0.01. #p < 0.05, ##p < 0.01, compared to Con. &p < 0.05, &&p < 0.01, compared to HG + GFP (HG). $ p < 0.05, $$p < 0.01, compared to HG + DCN.

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  Figure 6. The IGF1R antibody (αIGF1R) blocked the effects induced by overexpression of decorin. (A,B) The tube formation test; the photographs were taken at a magnification of 100×. (C,D) The cell wound healing test; the photographs were taken at a magnification of 100×. (E,F) The apoptosis assay. (G) CCK8 assessment. (H,I) The expression of VEGF, Bcl2, and Bax and the phosphorylation of AKT and AP 1. All data are presented as the mean ± SEM. *p < 0.05; **p < 0.01. #p < 0.05, ##p < 0.01, compared to Con. &p < 0.05, &&p < 0.01, compared to HG + GFP. $p < 0.05, $$p < 0.01, compared to HG + DCN.

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  Figure 7. Schematic of mechanisms of decorin-mediated signaling in high glucose-impaired angiogenesis. In endothelial cells, decorin overexpression activates IGF1R and promotes the phosphorylation of AKT and AP-1, which is inhibited by high glucose or hyperglycemia. The activation of AP-1 will upregulate the expression of VEGF, which increases proliferation, decreases apoptosis, and promotes migration and tube formation of the cells. Finally, all of these processes contribute to the promotion of angiogenesis and ameliorate DCM.