Design and structural basis of selective nonsteroidal inhibitors of aster cholesterol trafficking

Abstract

Significance Cholesterol transport by Aster proteins from the plasma membrane (PM) to the endoplasmic reticulum is important for cholesterol homeostasis. We identify nonsteroidal Aster inhibitors with improved specificity and reduced toxicity compared to sterol-based inhibitors. YKJ-124, a low-toxicity Aster-A preferring compound elevates PM-accessible cholesterol and potentiates Ca2+ flux in primary T cells. We identify Aster-C-selective inhibitors YKJ-300 and YKJ-305, with YKJ-305 shown to modulate liver cholesterol metabolism in mice. Cocrystal structures and mechanistic studies reveal that ligand specificity for Aster-C is conferred by a Ser477-dependent hydrogen bond. These compounds enable precise dissection of Aster-dependent cholesterol transport in specialized cells and in vivo, and support further efforts to optimize Aster inhibitors as potential therapeutics for diseases associated with cholesterol dysregulation.