Direct Interaction of Daxx and Androgen Receptor Is Required for Their Regulatory Activity in Cholesterol Biosynthesis

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.