BIOMEDICINE:
Receptor Offers Clues to How 'Good' Cholesterol Works
Larry Husten
Exactly how high density lipoprotein protects the arteries has been a mystery, but investigators now have their hands on a key to the answer: the receptor that enables cells to capture cholesterol from HDL particles in the bloodstream. The leading theory of how HDL safeguards arteries is that it somehow removes excess cholesterol from blood and tissue, then carries the excess to the liver and other tissues to be used to synthesize other substances, such as steroid hormones and bile acids. Now, in the 11 November issue of the Proceedings of the National Academy of Sciences, a research team provides the best evidence yet that a receptor identified during other studies is the key to HDL transport. The clinching evidence came when the team knocked out the mouse gene encoding the molecule, designated SR-BI. The researchers found--as expected--that the mice's blood cholesterol levels increased dramatically, while concentrations in organs that pick up cholesterol from HDL, such as the steroid-producing adrenal gland, dropped.
