MassIVE MSV000084689

Description

Apolipoprotein A-I (apoA-I) is cross-linked and dysfunctional in human atheroma. Although multiple mechanisms of apoA-1 cross-linking have been demonstrated in vitro, the in vivo mechanisms of cross-linking are not well established. We have recently demonstrated the highly selective and efficient modification of high-density lipoprotein (HDL) apoproteins by endogenous oxidized phospholipids (oxPLs), including oxoalkenal phospholipids. In the current study, we report that oxoalkenal phospholipids effectively cross-link apoproteins in HDL. We further demonstrate that cross-linking impairs the cholesterol efflux mediated by apoA-I or HDL3 in vitro and in vivo. Using LC-MS/MS analysis, we analyzed the pattern of apoprotein cross-linking in isolated human HDL either by synthetic oxoalkenal phospholipids or by oxPL generated during HDL oxidation in plasma by the physiologically relevant MPO-H2O2-NO2- system. We found that five histidine residues in helices 5-8 of apoA-I are preferably cross-linked by oxPL, forming stable pyrrole adducts with lysine residues in the helices 3-4 of another apoA-I or in the central domain of apoA-II. We also identified cross-links of apoA-I and apoA-II with two minor HDL apoproteins, apoA-IV and apoE. We detected a similar pattern of apoprotein cross-linking in oxidized murine HDL. We further detected oxPL cross-link adducts of HDL apoproteins in plasma and aorta of hyperlipidemic LDLR-/- mice, including cross-link adducts of apoA-I His-165--apoA-I Lys-93, apoA-I His-154--apoA-I Lys-105, apoA-I His-154--apoA-IV Lys-149, and apoA-II Lys-30/apoE His-227. These findings suggest an important mechanism that contributes to the loss of HDL's atheroprotective function in vivo. [doi:10.25345/C57Q32]

Keywords: oxidized phospholipids, oxidized phospholipid-apoprotein adduct, cholesterol efflux, crosslinking, high-density lipoprotein (HDL), atherosclerosis, cardiovascular disease, lipid metabolism, apolipoprotein A-I (apoA-I), atheroprotection

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