Atherosclerosis is a chronic inflammatory disease that is promoted by the consumption of dietary fat and cholesterol. The extent to which atherosclerosis progresses to cause coronary occlusion and/or death is mediated by the presence of plasma apoA-l, the main protein constituent of high density lipoproteins (HDL). The role of HDL apoA-l in whole body cholesterol homeostasis has been extensively investigated and its role is to direct cholesterol from the periphery to the liver for excretion. Despite intensive investigations, major questions remain regarding the mechanism by which apoA-l regulates cellular cholesterol levels and how the apoprotien's unique structural features facilitate cholesterol transport. To more completely understand the structural basis for apoA-l's role in cholesterol transport, we will carry out three specific aims that will clarify the structural reorganization necessary for the formation of nascent HDL via ABCA1.
In Aim 1 we propose to address the role of apoA-l in cholesterol homeostasis by determining the conformation of apoA-l on four different sized subclasses of ABCA1 generated nascent HDL. Also as part of Aim 1, we will examine the 'unfolding'steps'through which lipid-free apoA-l acquires lipid from ABCA1. To do this we will construct a series of 'tethered'disulfide apoA-l mutants that will prevent key intermediate unfolding steps through which the 4-helix bundle must transition as it organizes and binds phospholipid and cholesterol. In the Aim 2, we will investigate the mechanistic basis for the dominant negative repression of wild-type apoA-l HDL, as observed in humans who carry this mutation, by investigating the lipidation of the helix 6 mutant, L159R apoA-l by ABCA1. Our preliminary studies suggest that this single amino acid substitution mutant, L159R apoA-l, competes with wild-type apoA-l for phospholipid and cholesterol, resulting in a reduction in the overall lipidation of wild-type apoA-l by ABCA1 in a model cell culture system.
In Aim 3, we plan to determine whether the dominant negative phenotype associated with the L159R apoA-l mutant is pro- or antiatherogenic in hyperlipidemic mice. Using transgenic mice that express wild-type or L159R apoA-l, we will determine the extent to which the mutant apoA-l protects against the development of atherosclerosis, as well as investigating the in vivo basis for the low concentration of L159R apoA-l in plasma as it relates to the dominant negative phenotype.
|Schugar, Rebecca C; Shih, Diana M; Warrier, Manya et al. (2017) The TMAO-Producing Enzyme Flavin-Containing Monooxygenase 3 Regulates Obesity and the Beiging of White Adipose Tissue. Cell Rep 19:2451-2461|
|Pollard, Ricquita D; Fulp, Brian; Sorci-Thomas, Mary G et al. (2016) High-Density Lipoprotein Biogenesis: Defining the Domains Involved in Human Apolipoprotein A-I Lipidation. Biochemistry 55:4971-81|
|Rodríguez-Pérez, Celia; Ramprasath, Vanu Ramkumar; Pu, Shuaihua et al. (2016) Docosahexaenoic Acid Attenuates Cardiovascular Risk Factors via a Decline in Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Plasma Levels. Lipids 51:75-83|
|Warrier, Manya; Zhang, Jun; Bura, Kanwardeep et al. (2016) Sterol O-Acyltransferase 2-Driven Cholesterol Esterification Opposes Liver X Receptor-Stimulated Fecal Neutral Sterol Loss. Lipids 51:151-7|
|Jones, Peter J H; MacKay, Dylan S; Senanayake, Vijitha K et al. (2015) High-oleic canola oil consumption enriches LDL particle cholesteryl oleate content and reduces LDL proteoglycan binding in humans. Atherosclerosis 238:231-8|
|Lopez, Adam M; Chuang, Jen-Chieh; Posey, Kenneth S et al. (2015) PRD125, a potent and selective inhibitor of sterol O-acyltransferase 2 markedly reduces hepatic cholesteryl ester accumulation and improves liver function in lysosomal acid lipase-deficient mice. J Pharmacol Exp Ther 355:159-67|
|Liu, Mingxia; Allegood, Jeremy; Zhu, Xuewei et al. (2015) Uncleaved ApoM signal peptide is required for formation of large ApoM/sphingosine 1-phosphate (S1P)-enriched HDL particles. J Biol Chem 290:7861-70|
|Melchior, John T; Olson, John D; Kelley, Kathryn L et al. (2015) Targeted Knockdown of Hepatic SOAT2 With Antisense Oligonucleotides Stabilizes Atherosclerotic Plaque in ApoB100-only LDLr-/- Mice. Arterioscler Thromb Vasc Biol 35:1920-7|
|Ohshiro, Taichi; Ohtawa, Masaki; Nagamitsu, Tohru et al. (2015) New pyripyropene A derivatives, highly SOAT2-selective inhibitors, improve hypercholesterolemia and atherosclerosis in atherogenic mouse models. J Pharmacol Exp Ther 355:299-307|
|Cao, Qiang; Rong, Shunxing; Repa, Joyce J et al. (2014) Histone deacetylase 9 represses cholesterol efflux and alternatively activated macrophages in atherosclerosis development. Arterioscler Thromb Vasc Biol 34:1871-9|
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