title: Enlargement of high density lipoprotein in mice via liver X receptor activation requires apolipoprotein E and is abolished by cholesteryl ester transfer protein expression.
abstract: The factors involved in the generation of larger high density lipoprotein (HDL) particles, HDL1 and HDLc, are still not well understood. Administration of a specific synthetic liver X receptor (LXR) agonist, T0901317, in mice resulted in an increase of not only HDL cholesterol but also HDL particle size (Cao, G., Beyer, T. P., Yang, X. P., Schmidt, R. J., Zhang, Y., Bensch, W. R., Kauffman, R. F., Gao, H., Ryan, T. P., Liang, Y., Eacho, P. I., and Jiang, X. C. (2002) J. Biol. Chem. 277, 39561-39565). We have investigated the roles that apoE and CETP may play in this process. We treated apoE-deficient, cholesterol ester transport protein (CETP) transgenic, and wild type mice with various doses of the LXR agonist and monitored their HDL levels. Fast protein liquid chromatography and apolipoprotein analysis revealed that in apoE knockout mouse plasma, there was neither induction of larger HDL formation nor increase of HDL cholesterol, suggesting that apoE is essential for the LXR agonist effects on HDL metabolism. In CETP transgenic mice, CETP expression completely abolished LXR agonist-mediated HDL enlargement and greatly attenuated HDL cholesterol levels. Analysis of HDL particles by electron microscope and nondenaturing gel electrophoresis revealed similar findings. In apoE-deficient mice, LXR agonist also produced a significant increase in very low density lipoprotein/low density lipoprotein cholesterol and apolipoprotein B content. Our studies provide direct evidence that apoE and CETP are intimately involved in the accumulation of the enlarged HDL (HDL1 or HDLc) particles in mice.
authors.affiliation: Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA. xjiang@downstate.edu
authors.forename: Xian-Cheng
authors.initials: XC
authors.lastname: Jiang
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Beyer
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Quan
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schmidt
authors.forename: Youyan
authors.initials: Y
authors.lastname: Zhang
authors.forename: William R
authors.initials: WR
authors.lastname: Bensch
authors.forename: Patrick I
authors.initials: PI
authors.lastname: Eacho
authors.forename: Guoqing
authors.initials: G
authors.lastname: Cao
mesh_terms: D000818:Animals; D001057:Apolipoproteins E / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D053480:Cholesterol Ester Transfer Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins; D008075:Lipoproteins, HDL / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*
chemical_list: D001057:Apolipoproteins E; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins; D008075:Lipoproteins, HDL; D018160:Receptors, Cytoplasmic and Nuclear