The neutral lipid composition and size of recombinant high density lipoproteins regulates lecithin:cholesterol acyltransferase activity

1989 ◽  
Vol 67 (7) ◽  
pp. 358-364 ◽  
Author(s):  
D. L. Sparks ◽  
P. H. Pritchard
Keyword(s):  
Cholesteryl Ester ◽  
Neutral Lipid ◽  
Lipid Content ◽  
High Density ◽  
High Density Lipoproteins ◽  
Surface Lipid ◽  
Lecithin:Cholesterol Acyltransferase ◽  
Catalytic Potential ◽  
Neutral Lipid Content ◽  
Triacylglycerol Content

Recombinant high density lipoprotein (rHDL) particles were prepared from purified lipids and human apoproteins, and the ability of these complexes to act as substrates for purified lecithin:cholesterol acyltransferase (LCAT) was determined. Increasing the triacylglycerol content relative to cholesteryl ester in rHDL markedly decreased the maximum catalytic potential of LCAT. Kinetic analysis showed that the Vmax of the LCAT reaction was significantly and negatively correlated to the triacylglycerol content. The apparent Km was not directly affected by relative neutral lipid content, but was significantly related to protein and surface lipid content as well as to particle size. These results suggest that while particulate size may regulate the interaction between LCAT and HDL, the relative neutral lipid content of the particle may play a major role in regulating the catalytic potential of the enzyme, particularly with HDL from hypertriglyceridemic patients.Key words: high density lipoproteins, lecithin:cholesterol acyltransferase, model lipoproteins, triacylglycerol, cholesteryl ester.

Abstract 631: Lipid Composition of Gold Nanoparticle-Templated High-Density Lipoprotein Analogs Dictates Cholesterol Efflux Function

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
R Kannan Mutharasan ◽  
Amritha T Singh ◽  
Kaylin M McMahon ◽  
C Shad Thaxton
Keyword(s):  
Fatty Acid ◽  
Lipid Content ◽  
Lipid Composition ◽  
Reverse Cholesterol Transport ◽  
Cholesterol Efflux ◽  
Lipid Membrane ◽  
Density Lipoprotein ◽  
High Density ◽  
High Density Lipoproteins ◽  
Cholesterol Transport

Background: Reverse cholesterol transport, the process by which cholesterol is effluxed from cells to high-density lipoproteins (HDL) and is delivered to the liver for clearance, is a promising pathway to augment for treatment of atherosclerosis. Though structure-function relationships for nascent, discoidal HDL and cholesterol efflux have been well studied, how the lipid composition of spherical HDL species - which varies in pathophysiological conditions - impacts their ability to mediate cholesterol efflux has not been investigated. Methods and Results: Spherical gold nanoparticles (5 nm) were used to synthesize spherical HDL analogs (HDL-NP) by adding ApoAI protein, and various lipids. With this strategy a panel of HDL-NP varying in lipid content was generated. HDL-NP designs tested include: dipalmitylphosphatidylcholine (DPPC, saturated fatty acid), dioleoylphosphatidylcholine (DOPC, unsaturated fatty acid), sphingomyelin, lysophosphatidylcholine (LPC), and mixtures thereof. All of these species are found in natural HDL. After characterizing protein and lipid stoichiometry of the purified HDL-NP, these HDL-NP designs were tested in the cellular reverse cholesterol transport assay using J774 mouse macrophages. These studies demonstrate that all HDL-NP designs mediate more efflux than equimolar amounts of ApoAI protein control, and further demonstrate that HDL-NP designs incorporating unsaturated phospholipid (DOPC), sphingomyelin, and LPC - each of which can increase disorder in the lipid membrane and thus give rise to opportunity for cholesterol to intercalate and bind - enhance cholesterol efflux compared to saturated phospholipid (DPPC) design. Conclusion: In summary, these results demonstrate that lipid content of HDL-NP - analogs of spherical HDL - dictates cholesterol efflux function, a finding which sheds light on the functional importance of lipid content variation seen in mature, spherical HDL species.

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