Identification of a receptor mediating absorption of dietary cholesterol in the intestine

Here we show that scavenger receptor class B type I is present in the small -intestine brush border membrane where it facilitates the uptake of dietary cholesterol from either bile salt micelles or phospholipid vesicles. This receptor can also function as a port for several additional classes of lipi ds, including cholesteryl esters, triacylglycerols, and phospholipids, It i s the first receptor demonstrated to be involved in the absorption of dieta ry lipids in the intestine. In liver and steroidogenic tissues, the physiol ogical ligand of this receptor is high-density lipoprotein. We show that bi nding of high-density lipoprotein and apolipoprotein A-I to the brush borde r membrane-resident receptor inhibits uptake of cholesterol (sterol) into t he brush border membrane from lipid donor particles. This finding lends fur ther support to the conclusion that scavenger receptor BI catalyzes intesti nal cholesterol uptake. Our findings suggest new therapeutic approaches for limiting the absorption of dietary cholesterol and reducing hypercholester olemia and the risk of atherosclerosis.