TY - JOUR
T1 - Highly conserved amino acid residues in apolipoprotein A1 discordantly induce high density lipoprotein assembly in vitro and in vivo
AU - Yelamanchili, Dedipya
AU - Liu, Jing
AU - Gotto, Antonio M.
AU - Hurley, Ayrea E.
AU - Lagor, Willam R.
AU - Gillard, Baiba K.
AU - Davidson, W. Sean
AU - Pownall, Henry J.
AU - Rosales, Corina
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/12
Y1 - 2020/12
N2 - Objective: Apolipoprotein A1 (APOA1) is essential to reverse cholesterol transport, a physiologically important process that protects against atherosclerotic cardiovascular disease. APOA1 is a 28 kDa protein comprising multiple lipid-binding amphiphatic helices initialized by proline residues, which are conserved across multiple species. We tested the hypothesis that the evolutionarily conserved residues are essential to high density lipoprotein (HDL) function. Approach: We used biophysical and physiological assays of the function of APOA1P➔A variants, i.e., rHDL formation via dimyristoylphosphatidylcholine (DMPC) microsolubilization, activation of lecithin: cholesterol acyltransferase, cholesterol efflux from human monocyte-derived macrophages (THP-1) to each variant, and comparison of the size and composition of HDL from APOA1−/− mice receiving adeno-associated virus delivery of each human variant. Results: Differences in microsolubilization were profound and showed that conserved prolines, especially those in the C-terminus of APOA1, are essential to efficient rHDL formation. In contrast, P➔A substitutions produced small changes (−25 to +25%) in rates of cholesterol efflux and no differences in the rates of LCAT activation. The HDL particles formed following ectopic expression of each variant in APOA1−/− mice were smaller and more heterogeneous than those from control animals. Conclusion: Studies of DMPC microsolubilization show that proline residues are essential to the optimal interaction of APOA1 with membranes, the initial step in cholesterol efflux and HDL production. In contrast, P➔A substitutions modestly reduce the cholesterol efflux capacity of APOA1, have no effect on LCAT activation, but according to the profound reduction in the size of HDL formed in vivo, P➔A substitutions alter HDL biogenesis, thereby implicating other cellular and in vivo processes as determinants of HDL metabolism and function.
AB - Objective: Apolipoprotein A1 (APOA1) is essential to reverse cholesterol transport, a physiologically important process that protects against atherosclerotic cardiovascular disease. APOA1 is a 28 kDa protein comprising multiple lipid-binding amphiphatic helices initialized by proline residues, which are conserved across multiple species. We tested the hypothesis that the evolutionarily conserved residues are essential to high density lipoprotein (HDL) function. Approach: We used biophysical and physiological assays of the function of APOA1P➔A variants, i.e., rHDL formation via dimyristoylphosphatidylcholine (DMPC) microsolubilization, activation of lecithin: cholesterol acyltransferase, cholesterol efflux from human monocyte-derived macrophages (THP-1) to each variant, and comparison of the size and composition of HDL from APOA1−/− mice receiving adeno-associated virus delivery of each human variant. Results: Differences in microsolubilization were profound and showed that conserved prolines, especially those in the C-terminus of APOA1, are essential to efficient rHDL formation. In contrast, P➔A substitutions produced small changes (−25 to +25%) in rates of cholesterol efflux and no differences in the rates of LCAT activation. The HDL particles formed following ectopic expression of each variant in APOA1−/− mice were smaller and more heterogeneous than those from control animals. Conclusion: Studies of DMPC microsolubilization show that proline residues are essential to the optimal interaction of APOA1 with membranes, the initial step in cholesterol efflux and HDL production. In contrast, P➔A substitutions modestly reduce the cholesterol efflux capacity of APOA1, have no effect on LCAT activation, but according to the profound reduction in the size of HDL formed in vivo, P➔A substitutions alter HDL biogenesis, thereby implicating other cellular and in vivo processes as determinants of HDL metabolism and function.
KW - Apolipoprotein
KW - Cholesterol
KW - High density lipoproteins
KW - Metabolism
KW - Amino Acid Sequence
KW - Apolipoprotein A-I/chemistry
KW - Cholesterol/metabolism
KW - Humans
KW - Cells, Cultured
KW - Models, Molecular
KW - Lipoproteins, HDL/metabolism
KW - Animals
KW - Conserved Sequence
KW - Mice
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U2 - 10.1016/j.bbalip.2020.158794
DO - 10.1016/j.bbalip.2020.158794
M3 - Article
C2 - 32810603
AN - SCOPUS:85090032624
SN - 1388-1981
VL - 1865
SP - 158794
JO - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
JF - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
IS - 12
M1 - 158794
ER -