The Anti-atherogenic Activity of Beauveriolide Derivative BVD327, a Sterol O-Acyltransferase 2-Selective Inhibitor, in Apolipoprotein E Knockout Mice

Targeting Sterol O-Acyltransferase/Acyl-CoA:Cholesterol Acyltransferase (ACAT): A Perspective on Small-Molecule Inhibitors and Their Therapeutic Potential

Sterol O-acyltransferase (SOAT) is a membrane-bound enzyme that aids the esterification of cholesterol and fatty acids to cholesterol esters. SOAT has been studied extensively as a potential drug target, since its inhibition can serve as an alternative to statin therapy. Two SOAT isozymes that have discrete functions in the human body, namely, SOAT1 and SOAT2, have been characterized. Over three decades of research has focused on candidate SOAT1 inhibitors with unsatisfactory results in clinical trials. Recent research has focused on targeting SOAT2 selectively. In this perspective, we summarize the literature covering various SOAT inhibitory agents and discuss the design, structural requirements, and mode of action of SOAT inhibitors.

Antihyperlipidemic Activity of Gut-Restricted LXR Inverse Agonists

Hyperlipidemia and increased circulating cholesterol levels are associated with increased cardiovascular disease risk. The liver X receptors (LXRs) are regulators of de novo lipogenesis and cholesterol transport and have been validated as potential therapeutic targets for the treatment of atherosclerosis. However, efforts to develop LXR agonists to reduce cardiovascular diseases have failed due to poor clinical outcomes-associated increased hepatic lipogenesis and elevated low-density lipoprotein (LDL) cholesterol (C). Here, we report that LXR inverse agonists are effective in lowering plasma LDL cholesterol and triglycerides in several models of hyperlipidemia, including the Ldlr null mouse model of atherosclerosis. Mechanistic studies demonstrate that LXR directly regulates the expression of Soat2 enzyme in the intestine, which is directly responsible for the re-uptake or excretion of circulating lipids. Oral administration of a gut-specific LXR inverse agonist leads to reduction of Soat2 expression in the intestine and effectively lowers circulating LDL cholesterol and triglyceride levels without modulating LXR target genes in the periphery. In summary, our studies highlight the therapeutic potential of the gut-restricted molecules to treat hyperlipidemia and atherosclerosis through the intestinal LXR-Soat2 axis.

Dissecting cholesterol and phytosterol biosynthesis via mutants and inhibitors

Plants stand out among eukaryotes due to the large variety of sterols and sterol derivatives that they can produce. These metabolites not only serve as critical determinants of membrane structures, but also act as signaling molecules, as growth-regulating hormones, or as modulators of enzyme activities. Therefore, it is critical to understand the wiring of the biosynthetic pathways by which plants generate these distinct sterols, to allow their manipulation and to dissect their precise physiological roles. Here, we review the complexity and variation of the biosynthetic routes of the most abundant phytosterols and cholesterol in the green lineage and how different enzymes in these pathways are conserved and diverged from humans, yeast, and even bacteria. Many enzymatic steps show a deep evolutionary conservation, while others are executed by completely different enzymes. This has important implications for the use and specificity of available human and yeast sterol biosynthesis inhibitors in plants, and argues for the development of plant-tailored inhibitors of sterol biosynthesis.