Ca. Reardon et al., In vivo studies of HDL assembly and metabolism using adenovirus-mediated transfer of apoA-I mutants in apoA-I-deficient mice, BIOCHEM, 40(45), 2001, pp. 13670-13680
We have used adenovirus-mediated gene transfer in apoA-I-deficient (A-I-/-)
mice to probe the in vivo assembly and metabolism of HDL using apoA-I vari
ants, focusing primarily on the role of the C-terminal 32 amino acids (heli
ces 9-10). Lipid, lipoprotein, and apoA-I analyses showed that plasma level
s of apoA-I and HDL of the mutants were 40-88% lower than that of wild type
(WT) human apoA-I despite comparable levels of expression in the liver. WT
apoA-I and mutant 1 (P165A, E172A) formed spherical particles with the siz
e and density of HDL2 and HDL3. Mutant 2 (E234A, E235A, K238A, K239A) gener
ated spherical particles with density between HDL2 and HDL3. Mutant 3 (L211
V, L214V, L218V, L219V) and mutant 4 (L222K, F225K, F229K), which have subs
titutions of hydrophobic residues in the C-terminus, generated discoidal HD
L particles indicating a defect in their conversion to mature spherical HDL
. Significant amounts of mutant 4 and mutant 5 (truncated at residue 219) w
ere found in the lipid poor fractions after ultracentrifugation of the plas
ma (18 and 35%, respectively, of total apoA-I). These findings suggest that
hydrophobic residues in and/or between helices 9 and 10 are important for
the maturation of HDL in vivo.