Zhejun Cai1, Ye Ding1, Miao Zhang1, Qiulun Lu1, Shengnan Wu1, Huaiping Zhu1, Ping Song1, Ming-Hui Zou2. 1. From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Z.C., Y.D., Q.L., S.W., H.Z., P.S., M.-H.Z.); Department of Cardiology, Second Affiliated Hospital, Zhejiang University College of Medicine, Hangzhou, Zhejiang, China (Z.C.); and Department of Medicine, University of Oklahoma Health Sciences Center (M.Z.). 2. From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Z.C., Y.D., Q.L., S.W., H.Z., P.S., M.-H.Z.); Department of Cardiology, Second Affiliated Hospital, Zhejiang University College of Medicine, Hangzhou, Zhejiang, China (Z.C.); and Department of Medicine, University of Oklahoma Health Sciences Center (M.Z.). mzou@gsu.edu.
Abstract
RATIONALE: Atherosclerotic calcification is highly linked with plaque rapture. How calcification is regulated is poorly characterized. OBJECTIVE: We sought to determine the contributions of AMP-activated protein kinase (AMPK) in atherosclerotic calcification. METHODS AND RESULTS: Aortic calcification was evaluated in aortic roots and brachiocephalic arteries of atherosclerotic prone ApoE(-/-) mice or in mice with dual deficiencies of ApoE and AMPKα isoforms in whole body (ApoE(-/-)/AMPKα1(-/-) and ApoE(-/-)/AMPKα2(-/-)) or vascular smooth muscle cell (VSMC)-specific or macrophage-specific knockout of AMPKα1 fed with Western diet for 24 weeks. Genetic deficiency of AMPKα1 but not of AMPKα2 promoted atherosclerotic calcification and the expression of Runx2 (Runt-related transcription factor). Conversely, chronic administration of metformin, which activated AMPK, markedly reduced atherosclerotic calcification and Runx2 expression in ApoE(-/-) mice but had less effects in ApoE(-/-)/AMPKα1(-/-) mice. Furthermore, VSMC-specific but not macrophage-specific ablation of AMPKα1 promoted aortic calcification in vivo. Ablation of AMPKα1 in VSMC prevented Runx2 from proteasome degradation in parallel with aberrant osteoblastic differentiation of VSMC, whereas AMPK activation promoted Runx2 post-translational modification by small ubiquitin-like modifier (SUMO, SUMOylation), which is associated with its instability. Mechanically, we found that AMPKα1 directly phosphorylated protein inhibitor of activated STAT-1 (PIAS1), the SUMO E3-ligase of Runx2, at serine 510, to promote its SUMO E3-ligase activity. Finally, mutation of protein inhibitor of activated STAT-1 at serine 510 suppressed metformin-induced Runx2 SUMOylation and subsequently prevented metformin's effect on reducing oxidized low-density lipoprotein-triggered Runx2 expression in VSMC. CONCLUSIONS: AMPKα1 phosphorylated protein inhibitor of activated STAT-1 to promote Runx2 SUMOylation and subsequently lead to its instability. AMPKα1 deficiency in VSMC increased Runx2 expression and promoted atherosclerotic calcification in vivo.
RATIONALE: Atherosclerotic calcification is highly linked with plaque rapture. How calcification is regulated is poorly characterized. OBJECTIVE: We sought to determine the contributions of AMP-activated protein kinase (AMPK) in atherosclerotic calcification. METHODS AND RESULTS: Aortic calcification was evaluated in aortic roots and brachiocephalic arteries of atherosclerotic prone ApoE(-/-) mice or in mice with dual deficiencies of ApoE and AMPKα isoforms in whole body (ApoE(-/-)/AMPKα1(-/-) and ApoE(-/-)/AMPKα2(-/-)) or vascular smooth muscle cell (VSMC)-specific or macrophage-specific knockout of AMPKα1 fed with Western diet for 24 weeks. Genetic deficiency of AMPKα1 but not of AMPKα2 promoted atherosclerotic calcification and the expression of Runx2 (Runt-related transcription factor). Conversely, chronic administration of metformin, which activated AMPK, markedly reduced atherosclerotic calcification and Runx2 expression in ApoE(-/-) mice but had less effects in ApoE(-/-)/AMPKα1(-/-) mice. Furthermore, VSMC-specific but not macrophage-specific ablation of AMPKα1 promoted aortic calcification in vivo. Ablation of AMPKα1 in VSMC prevented Runx2 from proteasome degradation in parallel with aberrant osteoblastic differentiation of VSMC, whereas AMPK activation promoted Runx2 post-translational modification by small ubiquitin-like modifier (SUMO, SUMOylation), which is associated with its instability. Mechanically, we found that AMPKα1 directly phosphorylated protein inhibitor of activated STAT-1 (PIAS1), the SUMO E3-ligase of Runx2, at serine 510, to promote its SUMO E3-ligase activity. Finally, mutation of protein inhibitor of activated STAT-1 at serine 510 suppressed metformin-induced Runx2 SUMOylation and subsequently prevented metformin's effect on reducing oxidized low-density lipoprotein-triggered Runx2 expression in VSMC. CONCLUSIONS: AMPKα1 phosphorylated protein inhibitor of activated STAT-1 to promote Runx2 SUMOylation and subsequently lead to its instability. AMPKα1 deficiency in VSMC increased Runx2 expression and promoted atherosclerotic calcification in vivo.
Authors: Bindu Ramachandran; John N Stabley; Su-Li Cheng; Abraham S Behrmann; Austin Gay; Li Li; Megan Mead; Julia Kozlitina; Andrew Lemoff; Hamid Mirzaei; Zhijian Chen; Dwight A Towler Journal: J Biol Chem Date: 2018-04-06 Impact factor: 5.157