During the current grant period we characterized a number of LXR target genes including Abcgl, that is thought to function as a sterol transmembrane transporter. Abcgl was shown to be expressed at high levels, in a number of cell types including macrophages, B and T cells. We used cultured cells and Abcgl-/- mice to demonstrate that ABCG1 functions to flux sterols away from the endoplasmic reticulum to exogenous sterol acceptors, such as HDL. Loss of ABCG1 was associated with massive lipid accumulation, cytokine activation, inflammation and an increase in IgM-secreting B-1 cells. Importantly, bone marrow transplantation (BMT) studies identified a role for ABCG1 in the development of atherosclerosis. In collaboration with Project 6 we also demonstrated an unexpected and novel role for ABCG1 in T cell proliferation. We now propose to use two new mouse models, Abcgl-/-apoE-/- and Abcgl-/-Rag-/- double knockout mice: i) to test the hypothesis that loss of ABCG1 attenuates the development of atherosclerosis as a result of increased apoptosis, and to then identify the apoptotic pathway/mechanism involved, ii) to test the hypothesis that loss of ABCG1 from B and T cells (and possibly B-1 cells) also affects atherosclerosis. The latter studies will utilize adoptive transfer of B and T cells into Abcgl-/-RAG-/- mice followed by BMT into Ldlr-/- recipient mice. In preliminary studies we have identified multiple oxysterols that accumulate in Abcgl- /- macrophages in vivo. We now propose to better characterize the lipids and oxysterols that accumulate and then determine the mechanism by which these specific oxysterols/lipids promote apoptosis both in vivo and in vitro and induce massive cytokine expression, especially in macrophages lacking ABCGL We will also use state-of-the-art spinning disc microscopy and fluorescent-tagged wild type or mutant ABCG1 to follow intracellular movement of the transporter as a means of understanding how ABCG1 functions to flux sterols through intracellular vesicles to the cell surface. Finally, we will use a new cell-based assay to test the hypothesis that ABCG1, but but not ABCA1, functions to promote the efflux of specific sterols away from the endoplasmic reticulum.

Public Health Relevance

Lay Summary: The presence of cholesterol-loaded macrophages in the artery wall is associated with the development of atherosclerotic lesions and heart attacks. The current studies aim to explore mechanisms by which certain proteins move cholesterol out of cells and thus provide protection from inflammation and atherosclerosis.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Program Projects (P01)
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Heart, Lung, and Blood Initial Review Group (HLBP)
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University of California Los Angeles
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Hormozdiari, Farhad; van de Bunt, Martijn; Segrè, Ayellet V et al. (2016) Colocalization of GWAS and eQTL Signals Detects Target Genes. Am J Hum Genet 99:1245-1260
Seldin, Marcus M; Meng, Yonghong; Qi, Hongxiu et al. (2016) Trimethylamine N-Oxide Promotes Vascular Inflammation Through Signaling of Mitogen-Activated Protein Kinase and Nuclear Factor-κB. J Am Heart Assoc 5:
Zhu, Weifei; Gregory, Jill C; Org, Elin et al. (2016) Gut Microbial Metabolite TMAO Enhances Platelet Hyperreactivity and Thrombosis Risk. Cell 165:111-24
Shufelt, Chrisandra; Elboudwarej, Omeed; Johnson, B Delia et al. (2016) Carotid artery distensibility and hormone therapy and menopause: the Los Angeles Atherosclerosis Study. Menopause 23:150-7
Meriwether, David; Sulaiman, Dawoud; Wagner, Alan et al. (2016) Transintestinal transport of the anti-inflammatory drug 4F and the modulation of transintestinal cholesterol efflux. J Lipid Res 57:1175-93
Duong, Dat; Zou, Jennifer; Hormozdiari, Farhad et al. (2016) Using genomic annotations increases statistical power to detect eGenes. Bioinformatics 32:i156-i163
Tarling, Elizabeth J; Edwards, Peter A (2016) Intracellular Localization of Endogenous Mouse ABCG1 Is Mimicked by Both ABCG1-L550 and ABCG1-P550-Brief Report. Arterioscler Thromb Vasc Biol 36:1323-7
Chattopadhyay, Arnab; Navab, Mohamad; Hough, Greg et al. (2016) Tg6F ameliorates the increase in oxidized phospholipids in the jejunum of mice fed unsaturated LysoPC or WD. J Lipid Res 57:832-47
Hormozdiari, Farhad; Kang, Eun Yong; Bilow, Michael et al. (2016) Imputing Phenotypes for Genome-wide Association Studies. Am J Hum Genet 99:89-103
Lusis, Aldons J; Seldin, Marcus M; Allayee, Hooman et al. (2016) The Hybrid Mouse Diversity Panel: a resource for systems genetics analyses of metabolic and cardiovascular traits. J Lipid Res 57:925-42

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