Xiaoyan Dai1, Ye Ding1, Zhaoyu Liu1, Wencheng Zhang1, Ming-Hui Zou2. 1. From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (X.D., Y.D., Z.L., M.-H.Z.); The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health; and the State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.). 2. From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (X.D., Y.D., Z.L., M.-H.Z.); The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health; and the State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.). MZou@gsu.edu.
Abstract
RATIONALE: Elevated levels of CHOP (C/EBP homologous protein), a member of the C/EBP transcription factor family, in advanced atherosclerotic plaques is reported to be associated with atherosclerotic plaque rupture in humans. However, the molecular mechanism by which CHOP accumulation occurs is poorly defined. OBJECTIVE: The aim of this study was to investigate if (1) macrophage AMPK (AMP-activated protein kinase) regulates cellular CHOP accumulation and (2) whole-body Ampk deletion leads to neointimal disruption. METHODS AND RESULTS: In isolated or cultured macrophages, Ampkα1 deletion markedly increased apoptosis and CHOP, whereas pharmacological activation of AMPK dramatically reduced CHOP protein level via promoting CHOP degradation by proteasome. In addition, cotransfection of Chop-specific siRNA, but not control siRNA, markedly reduced apoptosis in macrophages transfected with Ampkα1-specific siRNA. Mechanistically, AMPKα1 was found to coimmunoprecipitate with CHOP and phosphorylate CHOP at serine 30. Furthermore, serine 30 phosphorylation of CHOP triggered its ubiquitination and proteasomal degradation. In a mouse model of plaque stability, deletion of Ampkα1 but not Ampkα2 promoted injury-induced neointimal disruption. This was paralleled by increased CHOP expression and apoptosis in vivo. Finally, transfection of Chop-specific siRNA but not control siRNA reduced both CHOP level and injury-induced neointimal disruption in vivo. CONCLUSIONS: Our results indicate that AMPKα1 mediates CHOP ubiquitination and proteasomal degradation in macrophages by promoting the phosphorylation of CHOP at serine 30. We conclude that AMPKα1 might be a valid therapeutic target in preventing atherosclerotic vulnerable plaque formation.
RATIONALE: Elevated levels of CHOP (C/EBP homologous protein), a member of the C/EBP transcription factor family, in advanced atherosclerotic plaques is reported to be associated with atherosclerotic plaque rupture in humans. However, the molecular mechanism by which CHOP accumulation occurs is poorly defined. OBJECTIVE: The aim of this study was to investigate if (1) macrophage AMPK (AMP-activated protein kinase) regulates cellular CHOP accumulation and (2) whole-body Ampk deletion leads to neointimal disruption. METHODS AND RESULTS: In isolated or cultured macrophages, Ampkα1 deletion markedly increased apoptosis and CHOP, whereas pharmacological activation of AMPK dramatically reduced CHOP protein level via promoting CHOP degradation by proteasome. In addition, cotransfection of Chop-specific siRNA, but not control siRNA, markedly reduced apoptosis in macrophages transfected with Ampkα1-specific siRNA. Mechanistically, AMPKα1 was found to coimmunoprecipitate with CHOP and phosphorylate CHOP at serine 30. Furthermore, serine 30 phosphorylation of CHOP triggered its ubiquitination and proteasomal degradation. In a mouse model of plaque stability, deletion of Ampkα1 but not Ampkα2 promoted injury-induced neointimal disruption. This was paralleled by increased CHOP expression and apoptosis in vivo. Finally, transfection of Chop-specific siRNA but not control siRNA reduced both CHOP level and injury-induced neointimal disruption in vivo. CONCLUSIONS: Our results indicate that AMPKα1 mediates CHOP ubiquitination and proteasomal degradation in macrophages by promoting the phosphorylation of CHOP at serine 30. We conclude that AMPKα1 might be a valid therapeutic target in preventing atherosclerotic vulnerable plaque formation.
Authors: F D Kolodgie; J Narula; A P Burke; N Haider; A Farb; Y Hui-Liang; J Smialek; R Virmani Journal: Am J Pathol Date: 2000-10 Impact factor: 4.307
Authors: Carlos Silvestre-Roig; Menno P de Winther; Christian Weber; Mat J Daemen; Esther Lutgens; Oliver Soehnlein Journal: Circ Res Date: 2014-01-03 Impact factor: 17.367
Authors: Allison M Manuel; Michael D Walla; Margaret T Dorn; Ross M Tanis; Gerardo G Piroli; Norma Frizzell Journal: Free Radic Biol Med Date: 2019-12-26 Impact factor: 7.376