The overall objective is to gain a more complete understanding of the structure of apolipoprotein (apo) E, especially as it relates to its anti-atherogenic properties, including the ability of the protein to bind to lipids, to heparin and other glycosaminoglycans (GAG), and to members of the low density lipoprotein receptor (LDLR) family. A range of engineered apo E molecules expressed in E. coli is being used to address 3 specific aims. 1) To understand the molecular features that control the binding of apoE and its common isoforms to lipid and lipoprotein particles of different sizes, the interactions of engineered forms of the protein with the surface of phospholipid-containing particles will be characterized using both in vitro and in vivo approaches. The hypothesis being tested is that formation of amphipathic a-helices with appropriate properties in the C-terminal domain of apoE controls lipid binding. 2) To characterize the lipid efflux and nascent apoE-HDL particle formation that occurs when apoE is a ligand for the ATP binding cassette transporter A1 (ABCA1) in neuronal cells. The hypothesis being tested is that certain properties of C-terminal a-helices in apoE control the sizes and compositions of the HDL particles released into the extracellular medium. 3) To understand how the receptor binding domain of apoE modulates its binding to different sulfated proteoglycans and GAG as compared to members of the LDLR family, the affinities and kinetics of interaction will be determined using surface plasmon resonance and cell-based assays. The hypothesis being tested is that high affinity interaction with different types of receptor requires a specific basic microenvironment in the apoE molecule. Overall, achievement of these 3 aims will generate novel quantitative information about the ways in which apoE structure and polymorphism affect the functional properties of the protein with respect to both lipid transport and cell signaling events. The design of apoE- mimetic molecules and of ways to control the aberrant behavior of certain isoforms of apoE will be facilitated by this understanding. Relevance: In the human population, apoE is expressed in 3 common forms that function differently in regulating lipid transport in vivo. As a result, these mutations in the apoE molecule can increase the risk for development of both cardiovascular disease and Alzheimer's disease. This project will provide more insights into the molecular mechanisms underlying these pathological effects.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL056083-11A1
Application #
7089574
Study Section
Integrative Nutrition and Metabolic Processes Study Section (INMP)
Program Officer
Srinivas, Pothur R
Project Start
1997-01-01
Project End
2010-02-28
Budget Start
2006-04-14
Budget End
2007-02-28
Support Year
11
Fiscal Year
2006
Total Cost
$412,916
Indirect Cost
Name
Children's Hospital of Philadelphia
Department
Type
DUNS #
073757627
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Mizuguchi, Chiharu; Hata, Mami; Dhanasekaran, Padmaja et al. (2014) Fluorescence study of domain structure and lipid interaction of human apolipoproteins E3 and E4. Biochim Biophys Acta 1841:1716-24
Nguyen, David; Dhanasekaran, Padmaja; Nickel, Margaret et al. (2014) Influence of domain stability on the properties of human apolipoprotein E3 and E4 and mouse apolipoprotein E. Biochemistry 53:4025-33
Li, Hui; Dhanasekaran, Padmaja; Alexander, Eric T et al. (2013) Molecular mechanisms responsible for the differential effects of apoE3 and apoE4 on plasma lipoprotein-cholesterol levels. Arterioscler Thromb Vasc Biol 33:687-93
Kothapalli, Devashish; Castagnino, Paola; Rader, Daniel J et al. (2013) Apolipoprotein E-mediated cell cycle arrest linked to p27 and the Cox2-dependent repression of miR221/222. Atherosclerosis 227:65-71
Phillips, Michael C (2013) New insights into the determination of HDL structure by apolipoproteins: Thematic review series: high density lipoprotein structure, function, and metabolism. J Lipid Res 54:2034-48
Mizuguchi, Chiharu; Hata, Mami; Dhanasekaran, Padmaja et al. (2012) Fluorescence analysis of the lipid binding-induced conformational change of apolipoprotein E4. Biochemistry 51:5580-8
Kothapalli, Devashish; Liu, Shu-Lin; Bae, Yong Ho et al. (2012) Cardiovascular protection by ApoE and ApoE-HDL linked to suppression of ECM gene expression and arterial stiffening. Cell Rep 2:1259-71
Nguyen, David; Dhanasekaran, Padmaja; Nickel, Margaret et al. (2010) Molecular basis for the differences in lipid and lipoprotein binding properties of human apolipoproteins E3 and E4. Biochemistry 49:10881-9
Lund-Katz, Sissel; Phillips, Michael C (2010) High density lipoprotein structure-function and role in reverse cholesterol transport. Subcell Biochem 51:183-227
Koyama, Mao; Tanaka, Masafumi; Dhanasekaran, Padmaja et al. (2009) Interaction between the N- and C-terminal domains modulates the stability and lipid binding of apolipoprotein A-I. Biochemistry 48:2529-37

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