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Journal of Lipid Research, Vol. 49, 572-580, March 2008
Copyright © 2008 by American Society for Biochemistry and Molecular Biology



* Center for Prevention of Obesity, Diabetes, and Cardiovascular Disease, Children's Hospital Oakland Research Institute, Oakland, CA 94609
Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720
Eli Lilly Research Laboratories, Indianapolis, IN 46285
Published, JLR Papers in Press, December 3, 2007.
1 To whom correspondence should be addressed. e-mail: tforte{at}chori.org
Transgenic (Tg) mice that overexpress the human apolipoprotein A-V gene (APOA5) yet lack an endogenous mouse apoa5 gene (APOA5 Tg mice) were generated. Subsequently, the effect of human apoA-V expression on plasma triglyceride (TG) concentration and lipoprotein and apolipoprotein distribution was determined and compared with that in mice deficient in apoA-V (apoa5–/– mice). NMR analysis of plasma lipoproteins revealed that APOA5 Tg mice had a very low VLDL concentration (26.4 ± 7.7 nmol/dl), whereas VLDL in apoa5–/– mice was 18- fold higher (467 ± 152 nmol/dl). SDS-PAGE analysis of the d < 1.063 g/ml plasma fraction revealed that the apoB-100/apoB-48 ratio was 14-fold higher in APOA5 Tg versus apoa5–/– mice and that the apoE/total apoB ratio was 7-fold greater in APOA5 Tg versus apoa5–/– mice. It is anticipated that a reduction in apoB-100/apoB-48 ratio as well as that for apoE/apoB would impair the uptake of VLDL and remnants in apoa5–/– mice, thereby contributing to increased plasma TG levels. The concentration of apoA-V in APOA5 Tg mice was 12.5 ± 2.9 µg/ml, which is
50- to 100-fold higher than that reported for normolipidemic humans. ApoA-V was predominantly associated with HDL but was rapidly and efficiently redistributed to apoA- V-deficient VLDL upon incubation. Consistent with findings reported for human subjects, apoA-V concentration was positively correlated with TG levels in normolipidemic APOA5 Tg mice. It is conceivable that, in a situation in which apoA-V is chronically overexpressed, complex interactions among factors regulating TG homeostasis may result in a positive correlation of apoA-V with TG concentrations.
Supplementary key words nuclear magnetic resonance redistribution of apolipoprotein A-V human apolipoprotein A-V transgenic mouse apolipoprotein A-V knockout mouse apolipoprotein A-V enzyme-linked immunosorbent assay apolipoprotein B-100 apolipoprotein E
Abbreviations: apoA-V, apolipoprotein A-V; apoa5–/–, apolipoprotein A-V-deficient; IDL, intermediate density lipoprotein; PVDF, polyvinylidene difluoride; Tg, transgenic; TG, triglyceride
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X. Shu, R. O. Ryan, and T. M. Forte Intracellular lipid droplet targeting by apolipoprotein A-V requires the carboxyl-terminal segment J. Lipid Res., August 1, 2008; 49(8): 1670 - 1676. [Abstract] [Full Text] [PDF] |
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