NPC1L1-dependent intestinal cholesterol absorption requires ganglioside GM3 in membrane microdomains

Intestinal Cholesterol absorption is a key regulator of systemic Cholesterol homeostasis. Excessive dietary Cholesterol and its intestinal uptake lead to hypercholesterolemia, a major risk factor for Cardiovascular Disease. Intestinal Cholesterol uptake is mediated by Niemann-Pick C1-like 1 (NPC1L1), a transmembrane protein localized in membrane microdomains (lipid rafts) enriched in gangliosides and Cholesterol. The roles of gangliosides, such as monosialodihexosylganglioside (GM3) and its synthesizing enzyme GM3 synthase (GM3S), in NPC1L1-dependent Cholesterol uptake have not been examined previously. Here, we examined NPC1L1-dependent Cholesterol uptake in a cell model as well as in wild-type and apoE-deficient mice fed normal or high-cholesterol diets. We showed that NPC1L1-dependent Cholesterol uptake was impaired in GM3S-deficient cells and that GM3S deficiency promoted resistance to hypercholesterolemia in both wild-type and apoE-deficient mice fed the high-cholesterol but not the normal diet. Our findings suggest that GM3 and related gangliosides are essential for NPC1L1-mediated intestinal Cholesterol absorption and are potential targets for hypercholesterolemia therapy.