Tian-Ping Li1,2,3, Shao-Wei Sun2, Guo-Zuo Xiong2, Fei Qiu1, Dong-Mei Yang1, Si-Yu Sun1, Xue-Jiao Xie1, Duan-Fang Liao1, Jian-Xiong Chen1,2,3,4, Qin-Hui Tuo5. 1. Medical School, Hunan University of Chinese Medicine, Changsha, China. 2. School of Pharmaceutical Science, University of South China, Hengyang, China. 3. School of Pharmaceutical Science, School of Polytechnic of Environment and Biology, Hengyang, China. 4. Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi, USA. 5. Medical School, Hunan University of Chinese Medicine, Changsha, China, qhtuo@aliyun.com.
Abstract
INTRODUCTION: Homeostasis of cholesterol is crucial for cellular function, and dysregulated cholesterol biosynthesis is a metabolic event that can lead to hepatic and cardiovascular abnormalities. OBJECTIVE: The aim of this study was to investigate the effects and mechanisms of domain-associated protein (Daxx) and androgen receptor (AR) on intracellular cholesterol synthesis. METHODS: HepG2 cells were transfected with pCDNA3.1(+)/Daxx plasmid or treated with testosterone propionate to observe the effects of Daxx and AR on intracellular cholesterol levels. Co-immunoprecipitation experiments were performed to identify the interaction between Daxx and AR and to explore the regulatory effects of this interaction on cholesterol synthesis. RESULTS: Our experiments showed that AR promoted cholesterol synthesis and accumulation by activating sterol-regulatory element-binding protein isoform 2. AR-induced cholesterol synthesis was inhibited by Daxx; however, the expression of AR was not affected. Further studies demonstrated the existence of direct binding between Daxx and AR and this interaction was required to suppress AR activity. CONCLUSIONS: The Daxx-mediated antagonism of AR depicts a more complete picture as to how Daxx regulates intracellular cholesterol level and provides a new target for treatment of atherosclerosis.
INTRODUCTION: Homeostasis of cholesterol is crucial for cellular function, and dysregulated cholesterol biosynthesis is a metabolic event that can lead to hepatic and cardiovascular abnormalities. OBJECTIVE: The aim of this study was to investigate the effects and mechanisms of domain-associated protein (Daxx) and androgen receptor (AR) on intracellular cholesterol synthesis. METHODS:HepG2 cells were transfected with pCDNA3.1(+)/Daxx plasmid or treated with testosterone propionate to observe the effects of Daxx and AR on intracellular cholesterol levels. Co-immunoprecipitation experiments were performed to identify the interaction between Daxx and AR and to explore the regulatory effects of this interaction on cholesterol synthesis. RESULTS: Our experiments showed that AR promoted cholesterol synthesis and accumulation by activating sterol-regulatory element-binding protein isoform 2. AR-induced cholesterol synthesis was inhibited by Daxx; however, the expression of AR was not affected. Further studies demonstrated the existence of direct binding between Daxx and AR and this interaction was required to suppress AR activity. CONCLUSIONS: The Daxx-mediated antagonism of AR depicts a more complete picture as to how Daxx regulates intracellular cholesterol level and provides a new target for treatment of atherosclerosis.