Influence of apolipoprotein A-I domain structure on macrophage reverse cholesterol transport in mice.
OBJECTIVE
The goal of this study was to determine the influence of apolipoprotein A-I (apoA-I) tertiary structure domain properties on the antiatherogenic properties of the protein. Two chimeric hybrids with the N-terminal domains swapped (human-mouse apoA-I and mouse-human apoA-I) were expressed in apoA-I-null mice with adeno-associated virus (AAV) and used to study macrophage reverse cholesterol transport (RCT) in vivo.


RESULTS
The different apoA-I variants were expressed in apoA-I-null mice that were injected with [H(3)]cholesterol-labeled J774 mouse macrophages to measure RCT. Significantly more cholesterol was removed from the macrophages and deposited in the feces via the RCT pathway in mice expressing mouse-H apoA-I compared with all other groups. Analysis of the individual components of the RCT pathway demonstrated that mouse-H apoA-I promoted ATP-binding cassette transporter A1-mediated cholesterol efflux more efficiently than all other variants, as well as increasing the rate of cholesterol uptake into liver cells.


CONCLUSIONS
The structural domain properties of apoA-I affect the ability of the protein to mediate macrophage RCT. Replacement of the N-terminal helix bundle domain in the human apoA-I with the mouse apoA-I counterpart causes a gain of function with respect to macrophage RCT, suggesting that engineering some destabilization into the N-terminal helix bundle domain or increasing the hydrophobicity of the C-terminal domain of human apoA-I would enhance the antiatherogenic properties of the protein.
Children's Hospital of Philadelphia, 3615 Civic Center Blvd., Philadelphia, PA 19104, USA.
Eric T
ET
Alexander
Charulatha
C
Vedhachalam
Sandhya
S
Sankaranarayanan
Margarita
M
de la Llera-Moya
George H
GH
Rothblat
Daniel J
DJ
Rader
Michael C
MC
Phillips
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D016632:Apolipoprotein A-I / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D002784:Cholesterol / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D023421:Models, Animal; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D011973:Receptors, LDL / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D016632:Apolipoprotein A-I; D011973:Receptors, LDL; D002784:Cholesterol