Enantiospecificity of cholesterol function in vivo

The importance of the absolute configuration of cholesterol for its function in vivo is unknown. To directly test this question in viva, we synthesized the enantiomer of cholesterol (ent-cholesterol) and tested its ability to substitute for natural cholesterol (not-cholesterol) in the growth, viability, and behavior of Caenorhabditis elegans, a cholesterol auxotroph. First-generation animals grown on ent-cholesterol were viable with only mild behavioral defects. However, ent-cholesterol produced 100% lethality/arrest of their second generation progeny. Isotopically labeled ent-cholesterol incorporated into animals, indicating that its lethality was not secondary to cholesterol starvation. When mixed with not-cholesterol, ent-cholesterol was not inert; rather, it antagonized the activity of not-cholesterol. These results demonstrate for the first tine that the absolute configuration of cholesterol, not just its physical properties, is essential for its functions in viva.