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This Article Full Text Full Text (PDF) All Versions of this Article: 296/5/E1110    most recent 90964.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Huang, Z. H. Articles by Mazzone, T. Search for Related Content PubMed PubMed Citation Articles by Huang, Z. H. Articles by Mazzone, T.

Role of adipocyte-derived apoE in modulating adipocyte size, lipid metabolism, and gene expression in vivo

¹Department of Medicine and ²Departments of Medicine, Pharmacology, and Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois

Submitted 1 December 2008 ; accepted in final form 12 February 2009

Adipocytes isolated from apolipoprotein E (apoE)-knockout (EKO) mice display alterations in triglyceride (TG) metabolism and gene expression. The present studies were undertaken to evaluate the impact of endogenously produced adipocyte apoE on these adipocyte parameters in vivo, independent of the profoundly disturbed metabolic milieu of EKO mice. Adipose tissue from wild-type (WT) or EKO mice was transplanted into WT recipients, which were then fed chow or high-fat diet for 8–10 wk. After a chow diet, freshly isolated transplanted EKO adipocytes were significantly (P < 0.05) smaller (70%) than transplanted WT adipocytes and displayed significantly lower rates of TG synthesis and higher rates of TG hydrolysis. Transplanted EKO adipocytes also had higher mRNA levels for adiponectin, perilipin, and genes coding for enzymes in the fatty acid oxidation pathway and lower levels of caveolin. After a high-fat diet and consequent increase in circulating lipid and apoE levels, transplanted WT adipocyte size increased by 106 x 10³ µm³, whereas EKO adipocyte size increased only by 19 x 10³ µm³. Endogenous host adipose tissue harvested from WT recipients of transplanted WT or EKO adipose tissue did not demonstrate any difference in adipocyte size. Consistent with the in vivo observations, EKO adipocytes synthesized less TG when incubated with apoE-containing TG-rich lipoproteins than WT adipocytes. Our results establish a novel in vivo role for endogenously produced apoE, distinct from circulating apoE, in modulation of adipocyte TG metabolism and gene expression. They support a model in which endogenously produced adipocyte apoE facilitates adipocyte lipid acquisition from circulating TG-rich lipoproteins.

obesity; adipose tissue; apolipoproteins

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				Z. H. Huang, R. D. Minshall, and T. Mazzone Mechanism for Endogenously Expressed ApoE Modulation of Adipocyte Very Low Density Lipoprotein Metabolism: ROLE IN ENDOCYTIC AND LIPASE-MEDIATED METABOLIC PATHWAYS J. Biol. Chem., November 13, 2009; 284(46): 31512 - 31522. [Abstract] [Full Text] [PDF]