The long-term objective of this research is to understand the role of acyl-coenzyme A:cholesterol acyltransferase (ACAT) in human health and disease, particularly in atherosclerosis, a leading cause of morbidity and mortality worldwide. The current proposal has two main goals: to continue to conduct structure-function analysis of ACAT1 in vitro, and to examine the role of macrophage ACAT1 in vivo in the Apoe-/- mouse model and the Ldlr-/- apoB48-deficient mouse model for atherosclerosis. As a key enzyme in cellular cholesterol metabolism, ACAT utilizes cholesterol and long-chain fatty acyl coenzyme A to produce cholesteryl esters, and is allosterically activated by its own substrate, cholesterol, to guard against excess buildup of cholesterol at the endoplasmic reticulum. ACAT1 is the major isoenzyme of ACAT in macrophages and plays a key role in foam cell formation in the early stages of atherosclerosis. ACAT1 is also expressed in many other cell types, including hematopoietic stem cells in the bone marrow. The physiological roles of ACAT1 in various tissues remain to be carefully investigated. Thus, the aims of this project are 1) to identify key amino acid residues involved in substrate binding, catalysis, and/or allosteric control of ACAT1;and 2) to delineate the effects of inactivating macrophage Acat1 during the initiation and progression stages of atherosclerosis. We will employ a new procedure for expression and purification of the recombinant hACAT1 enzyme and seven different biochemical assays to pursue Aim 1, and will employ a newly developed macrophage-specific Acat1 KO mouse (Acat1-M/-M) model as a novel reagent to pursue Aim 2. ACAT1 is a potential target for treating Alzheimer disease and other diseases in humans. Most of the ACAT inhibitors currently available cause non-specific cytotoxicities and inhibit other enzymes with similar active sites, potentially causing other adverse side effects. The outcome of this application will help investigators to design ACAT1-specific inhibitors with minimal side effects, and help to determine the utility of ACAT1 as a target for treating atherosclerosis.

Public Health Relevance

The long-term objective of this research is to understand the role of acyl-coenzyme A:cholesterol acyltransferase (ACAT) in cellular cholesterol homeostasis. ACAT1 is a potential drug target for treating Alzheimer disease and other diseases in humans. The outcome of this application will help investigators to design ACAT1-specific inhibitors with minimal adverse side effects.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL060306-15
Application #
8437169
Study Section
Integrative Nutrition and Metabolic Processes Study Section (INMP)
Program Officer
Srinivas, Pothur R
Project Start
1998-04-01
Project End
2016-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
15
Fiscal Year
2013
Total Cost
$390,320
Indirect Cost
$146,965
Name
Dartmouth College
Department
Biochemistry
Type
Schools of Medicine
DUNS #
041027822
City
Hanover
State
NH
Country
United States
Zip Code
03755
Huang, Li-Hao; Melton, Elaina M; Li, Haibo et al. (2016) Myeloid Acyl-CoA:Cholesterol Acyltransferase 1 Deficiency Reduces Lesion Macrophage Content and Suppresses Atherosclerosis Progression. J Biol Chem 291:6232-44
Yang, Wei; Bai, Yibing; Xiong, Ying et al. (2016) Potentiating the antitumour response of CD8(+) T cells by modulating cholesterol metabolism. Nature 531:651-5
Yamauchi, Yoshio; Yokoyama, Shinji; Chang, Ta-Yuan (2016) ABCA1-dependent sterol release: sterol molecule specificity and potential membrane domain for HDL biogenesis. J Lipid Res 57:77-88
Rogers, Maximillian A; Liu, Jay; Song, Bao-Liang et al. (2015) Acyl-CoA:cholesterol acyltransferases (ACATs/SOATs): Enzymes with multiple sterols as substrates and as activators. J Steroid Biochem Mol Biol 151:102-7
Yamauchi, Yoshio; Iwamoto, Noriyuki; Rogers, Maximillian A et al. (2015) Deficiency in the Lipid Exporter ABCA1 Impairs Retrograde Sterol Movement and Disrupts Sterol Sensing at the Endoplasmic Reticulum. J Biol Chem 290:23464-77
Poirier, Steve; Samami, Samaneh; Mamarbachi, Maya et al. (2014) The epigenetic drug 5-azacytidine interferes with cholesterol and lipid metabolism. J Biol Chem 289:18736-51
Huang, Li-Hao; Nishi, Koji; Li, Song et al. (2014) Acyl-coenzyme A:cholesterol acyltransferase 1 - significance of single-nucleotide polymorphism at residue 526 and the role of Pro347 near the fifth transmembrane domain. FEBS J 281:1773-83
Huang, Li-Hao; Gui, Jingang; Artinger, Erika et al. (2013) Acat1 gene ablation in mice increases hematopoietic progenitor cell proliferation in bone marrow and causes leukocytosis. Arterioscler Thromb Vasc Biol 33:2081-7
Hu, Guang-Jing; Chen, Jia; Zhao, Xiao-Nan et al. (2013) Production of ACAT1 56-kDa isoform in human cells via trans-splicing involving the ampicillin resistance gene. Cell Res 23:1007-24
Lu, Ming; Hu, Xi-Han; Li, Qin et al. (2013) A specific cholesterol metabolic pathway is established in a subset of HCCs for tumor growth. J Mol Cell Biol 5:404-15

Showing the most recent 10 out of 38 publications