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Apolipoprotein M is required for prebeta-HDL formation and cholesterol efflux to HDL and protects against atherosclerosis.

Wolfrum C, Poy MN, Stoffel M

The Laboratory of Metabolic Diseases, The Rockefeller University, 1230 York Avenue, New York, New York 10021, USA.

High-density lipoproteins (HDLs) are considered antiatherogenic because they mediate reverse cholesterol transport from the periphery to the liver for excretion and degradation. Here we show that mice deficient in apolipoprotein M (apoM), a component of the HDL particle, accumulated cholesterol in large HDL particles (HDL(1)) while the conversion of HDL to prebeta-HDL was impaired. Accordingly, apoM-deficient mice lacked prebeta-HDL, a subclass of lipid-poor apolipoproteins that serves as a key acceptor of peripheral cellular cholesterol. This deficiency led to a markedly reduced cholesterol efflux from macrophages to apoM-deficient HDL compared to normal HDL in vitro. Overexpression of apoM in Ldlr(-/-) mice protected against atherosclerosis when the mice were challenged with a cholesterol-enriched diet, showing that apoM is important for the formation of prebeta-HDL and cholesterol efflux to HDL, and thereby inhibits formation of atherosclerotic lesions.

Published 6 April 2005 in Nat Med, 11(4): 418-22.
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