Wakako Takabe1, Rongsong Li, Lisong Ai, Fei Yu, Judith A Berliner, Tzung K Hsiai. 1. Department of Biomedical Engineering and Division of Cardiovascular Medicine, School of Medicine and School of Engineering, University of Southern California, 1042 Downey Way, Los Angeles, CA 90089, USA.
Abstract
OBJECTIVE: Oxidized low-density lipoprotein (oxLDL) modulates intracellular redox status and induces apoptosis in endothelial cells. However, the signal pathways and molecular mechanism remain unknown. In this study, we investigated the role of manganese superoxide dismutase (Mn-SOD) on oxLDL-induced apoptosis via c-Jun NH2-terminal kinase (JNK)-mediated ubiquitin/proteasome pathway. METHODS AND RESULTS: OxLDL induced JNK phosphorylation that peaked at 30 minutes in human aortic endothelial cells. Fluorescence-activated cell sorting analysis revealed that oxLDL increased mitochondrial superoxide production by 1.88+/-0.19-fold and mitochondrial membrane potential by 18%. JNK small interference RNA (siJNK) reduced oxLDL-induced mitochondrial superoxide production by 88.4% and mitochondrial membrane potential by 61.7%. OxLDL did not affect Mn-SOD mRNA expression, but it significantly reduced Mn-SOD protein level, which was restored by siJNK. Immunoprecipitation by ubiquitin antibody revealed that oxLDL increased ubiquitination of Mn-SOD, which was inhibited by siJNK. OxLDL-induced caspase-3 activities were also attenuated by siJNK but were enhanced by Mn-SOD small interfering RNA. Furthermore, overexpression of Mn-SOD abrogated oxLDL-induced caspase-3 activities. CONCLUSIONS: OxLDL-induced JNK activation regulates mitochondrial redox status and Mn-SOD protein degradation via JNK-dependent ubiquitination, leading to endothelial cell apoptosis.
OBJECTIVE: Oxidized low-density lipoprotein (oxLDL) modulates intracellular redox status and induces apoptosis in endothelial cells. However, the signal pathways and molecular mechanism remain unknown. In this study, we investigated the role of manganese superoxide dismutase (Mn-SOD) on oxLDL-induced apoptosis via c-Jun NH2-terminal kinase (JNK)-mediated ubiquitin/proteasome pathway. METHODS AND RESULTS: OxLDL induced JNK phosphorylation that peaked at 30 minutes in human aortic endothelial cells. Fluorescence-activated cell sorting analysis revealed that oxLDL increased mitochondrial superoxide production by 1.88+/-0.19-fold and mitochondrial membrane potential by 18%. JNK small interference RNA (siJNK) reduced oxLDL-induced mitochondrial superoxide production by 88.4% and mitochondrial membrane potential by 61.7%. OxLDL did not affect Mn-SOD mRNA expression, but it significantly reduced Mn-SOD protein level, which was restored by siJNK. Immunoprecipitation by ubiquitin antibody revealed that oxLDL increased ubiquitination of Mn-SOD, which was inhibited by siJNK. OxLDL-induced caspase-3 activities were also attenuated by siJNK but were enhanced by Mn-SOD small interfering RNA. Furthermore, overexpression of Mn-SOD abrogated oxLDL-induced caspase-3 activities. CONCLUSIONS: OxLDL-induced JNK activation regulates mitochondrial redox status and Mn-SOD protein degradation via JNK-dependent ubiquitination, leading to endothelial cell apoptosis.
Authors: Elena Osto; Christian M Matter; Alexei Kouroedov; Tadeusz Malinski; Markus Bachschmid; Giovanni G Camici; Ulkan Kilic; Thomas Stallmach; Jan Boren; Sabino Iliceto; Thomas F Lüscher; Francesco Cosentino Journal: Circulation Date: 2008-10-27 Impact factor: 29.690
Authors: Lisong Ai; Mahsa Rouhanizadeh; Joseph C Wu; Wakako Takabe; Hongyu Yu; Mohammad Alavi; Rongsong Li; Yi Chu; Jordan Miller; Donald D Heistad; Tzung K Hsiai Journal: Am J Physiol Cell Physiol Date: 2008-04-23 Impact factor: 4.249
Authors: Kyle S McCommis; Allison M McGee; M Harold Laughlin; Douglas K Bowles; Christopher P Baines Journal: Am J Physiol Regul Integr Comp Physiol Date: 2011-08-24 Impact factor: 3.619
Authors: Kyung In Baek; René R Sevag Packard; Jeffrey J Hsu; Arian Saffari; Zhao Ma; Anh Phuong Luu; Andrew Pietersen; Hilary Yen; Bin Ren; Yichen Ding; Constantinos Sioutas; Rongsong Li; Tzung K Hsiai Journal: Antioxid Redox Signal Date: 2017-11-17 Impact factor: 8.401