1 research outputs found
A Targeted, Differential Top-Down Proteomic Methodology for Comparison of ApoA‑I Proteoforms in Individuals with High and Low HDL Efflux Capacity
Top-down proteomics (TDP) allows
precise determination/characterization of the different proteoforms
derived from the expression of a single gene. In this study, we targeted
apolipoprotein A-I (ApoA-I), a mediator of high-density-lipoprotein
cholesterol efflux (HDL-E), which is inversely associated with coronary
heart disease risk. Absolute ApoA-I concentration and allelic variation
only partially explain interindividual HDL-E variation. Therefore,
we hypothesize that differences in HDL-E are associated with the abundances
of different ApoA-I proteoforms. Here, we present a targeted TDP methodology
to characterize ApoA-I proteoforms in serum samples and compare their
abundances between individuals. We characterized 18 ApoA-I proteoforms
using selected-ion monitoring coupled to electron-transfer dissociation
mass spectrometry. We then compared the abundances of these proteoforms
between two groups of four participants, representing the individuals
with highest and lowest HDL-E values within the Chicago Healthy Aging
Study (<i>n</i> = 420). Six proteoforms showed significantly
(<i>p</i> < 0.0005) higher intensity in high HDL-E individuals:
canonical ApoA-I [fold difference (fd) = 1.17], carboxymethylated
ApoA-I (fd = 1.24) and, with highest difference, four fatty acylated
forms: palmitoylated (fd = 2.16), oleoylated (fd = 2.08), arachidonoylated
(fd = 2.31) and one bearing two modifications: palmitoylation and
truncation (fd = 2.13). These results demonstrate translational potential
for targeted TDP in revealing, with high sensitivity, associations
between interindividual proteoform variation and physiological differences
underlying disease risk