Sirtuin 3 is essential for hypertension‐induced cardiac fibrosis via mediating pericyte transition

FIGURE 1. Hypertension interacted with SIRT3 expression. A, SIRT3 expression was decreased in WT mice + Ang‐II (n = 3 mice) compared to WT mice (n = 3 mice). Mean ± SEM, *P < .05. B, Systolic pressure, diastolic pressure and mean arterial pressure (MAP) were significantly enhanced in WT mice + Ang‐II compared to WT mice (n = 9 mice), and knockout of SIRT3 further increased these elevations (n = 9 mice). Mean ± SEM, *P < .05

FIGURE 2. Knockout of SIRT3 enhanced Ang‐II‐induced cardiac hypertrophy and dysfunction. A, No significant difference was found between WT mice and WT mice + Ang‐II. Decreased CFR was found in SIRT3KO mice + Ang‐II compared to WT mice + Ang‐II (n = 11‐12 mice). Mean ± SEM, *P < .05, **P < .01, ****P < .0001. B, Ang‐II treatment impaired diastolic function as evidence by increases in IVRT in comparison with WT mice. Knockout of SIRT3 further enhanced Ang‐II‐induced elevation of IVRT (n = 13‐5 mice). Mean ± SEM,*P < .05, **P < .01, ***P < .001, ****P < .0001. C, Knockout of SIRT3 resulted in a further decline of EF and FS induced by Ang‐II infusion (n = 13‐5 mice). Mean ± SEM *P < .05, ***P < .001, ****P < .0001. D, HW/BW was increased in WT mice + Ang‐II compared to WT mice. Cardiomyocyte size was increased by Ang‐II compared to WT mice. Significant difference was found between WT mice + Ang‐II and SIRT3KO mice + Ang‐II. Ang‐II up‐regulated expression of β‐MHC in SIRT3KO mice + Ang‐II (n = 4 mice) in comparison with SIRT3KO mice (n = 3 mice). Knockout of SIRT3 also increased expression of β‐MHC after Ang‐II infusion (n = 4 mice) compared to WT mice + Ang‐II (n = 4 mice). Mean ± SEM, *P <…

FIGURE 3. Knockout of SIRT3 accentuated Ang‐II‐induced fibrosis. A, Masson's trichrome staining showed that interstitial fibrosis was increased significantly in WT mice + Ang‐II (n = 4 mice) and knockout of SIRT3 (n = 4 mice) further enhanced this increase as compared to WT mice + Ang‐II. Knockout of SIRT3 promoted Ang‐II‐induced coronary artery remodelling. Perivascular fibrosis and increased wall‐lumen ratio were found in WT mice + Ang‐II (n = 4 mice); these alterations were accentuated by knockout of SIRT3. Mean ± SEM, *P < .05, **P < .01. B, Immunostaining revealed a significant increases in FSP‐1 and α‐SMA levels in NG2‐DsRed mice + Ang‐II (n = 4 mice), and levels of FSP‐1 and α‐SMA were further increased by knockout of SIRT3. Mean ± SEM, *P < .05, **P < .01

FIGURE 4. Knockout of SIRT3 promoted Ang‐II‐induced pericyte recruitment and transition. A, Immunostaining data showed there was a significant increase of NG2‐DsRed+ pericytes in NG2‐DsRed mice + Ang‐II (n = 4 mice) compared to NG2‐DsRed mice (n = 3 mice). NG2‐DsRed+ pericytes were further enhanced in NG2‐DsRed‐SIRT3KO mice + Ang‐II (n = 4 mice) in comparison with NG2‐DsRed mice + Ang‐II (n = 4 mice). Ang‐II significantly enhanced numbers of DsRed+ and PDGFR‐β+ pericytes; knockout of SIRT3 further enhanced the Ang‐II‐induced changes. Mean ± SEM, *P < .05, **P < .01. B, Knockout of SIRT3 enhanced Ang‐II‐induced pericyte transition. Images and analysis revealing FSP‐1+/DsRed+ and α‐SMA+/DsRed+ double‐positive cells in all groups of mice. The numbers of both FSP‐1+/DsRed+ and α‐SMA+/DsRed+ double‐positive cells were enhanced in NG2‐DsRed mice + Ang‐II (n = 4 mice) compared to NG2‐DsRed mice (n = 3 mice), and knockout of SIRT3 further developed these increases. Mean ± SEM, *P < .05, **P < .01. C, Images and analysis revealing collagen‐I+/NG2+ pericytes presented in all groups of mice. The numbers of collagen‐I+/NG2+ double‐positive cells were enhanced in NG2‐DsRed mice + Ang‐II (n = 4 mice)…

FIGURE 5. Knockout of SIRT3 further increased Ang‐II‐induced up‐regulation of TGF‐β1 expression. A, Knockout of SIRT3 sensitized Ang‐II‐induced up‐regulation of TGF‐β1. Immunostaining and Western blot analysis revealed a significant increase in TGF‐β1 expression in NG2‐DsRed mice or WT mice + Ang‐II (n = 4 mice). Knockout of SIRT3 further accentuated this up‐regulation. Mean ± SEM, *P < .05, **P < .01. B, Image revealing TGF‐β1+/DsRed+ pericytes presented in all groups of mice. The numbers of TGF‐β1+/DsRed+ double‐positive cell were increased in NG2‐DsRed mice + Ang‐II (n = 4) compared to NG2‐DsRed mice (n = 3 mice), and knockout of SIRT3 further increased numbers of TGF‐β1+/DsRed+ pericyte. Mean ± SEM, *P < .05, **P < .01

FIGURE 6. Knockout of SIRT3 promoted Ang‐II‐induced NADPH oxidase‐derived ROS formation. A, With immunostaining of DHE, there was a significant increase of integrated density in WT mice + Ang‐II (n = 4 mice) compared to WT mice (n = 3 mice). Integrated density was further increased in SIRT3KO mice + Ang‐II (n = 4) in comparison with WT mice + Ang‐II (n = 4 mice). Mean ± SEM, *P < .05, **P < .01. B, Western blot analysis revealed that Ang‐II up‐regulated expression of gp91phox and p47phox in the hearts. These gene expressions were significantly up‐regulated by knockout of SIRT3 in the Ang‐II‐treated hearts. Mean ± SEM, *P < .05, **P < .01

FIGURE 7. Proposal working model of Ang‐II‐induced fibrosis via suppressing SIRT3. Ang‐II causes a reduction of SIRT3 expression in the hearts. Reduction of SIRT3 leads to a significant increase in ROS formation and TGF‐β expression. Reduction of SIRT3 also promotes pericyte‐myofibroblast transitions. These abnormalities result in perivascular fibrosis and myocardial fibrosis, which caused a cardiac dysfunction