J. Teruya et al., MODE OF TRANSPORT OF FATTY-ACID TO ENDOTHELIAL-CELLS INFLUENCES INTRACELLULAR FATTY-ACID METABOLISM, Journal of lipid research, 36(2), 1995, pp. 266-276
Fatty acids are transported to cells from a variety of different moiet
ies in the plasma. In this study, using oleate and human umbilical vei
n endothelial cells, we asked whether the vehicle that delivers fatty
acid to cells has an influence on its metabolism upon its incorporatio
n into the cell. For oleate vehicles, we compared free oleate bound to
albumin with oleate in low density lipoprotein (LDL) which was delipi
dated and reconstituted with either radiolabeled triolein or cholester
yl oleate. Using approximately physiologic concentrations of LDL and f
ree oleate, we demonstrated by three lines of evidence unique patterns
of cellular oleate metabolism for oleate delivered as triolein within
LDL, for oleate delivered as cholesteryl oleate within LDL, and for o
leate delivered as free oleate bound to albumin. In fact, the differen
ce was most marked between cholesteryl oleate and triolein, even thoug
h the oleate in cholesteryl oleate and triolein was delivered in ident
ically reconstituted LDL particles, which were presumably incorporated
into the cells and degraded in lysosomes in a similar fashion. First,
we demonstrated that oleate delivered as free oleate or as triolein i
n reconstituted LDL was desaturated and elongated to fatty acid metabo
lites, but cholesteryl oleate in reconstituted LDL was not similarly m
etabolized. The elongated and desaturated metabolites of oleate were p
referentially esterified in cellular triglyceride when oleate was deli
vered as free oleate, but they were preferentially esterified in phosp
holipids when oleate was delivered as triolein in LDL. Second, we obse
rved that there was a difference in the distribution of oleate among p
hospholipids when oleate was delivered as cholesteryl oleate in recons
tituted LDL versus triolein in reconstituted LDL. When the oleate was
delivered as triolein in reconstituted LDL, there was greater esterifi
cation in diacyl phosphatidylethanolamine, in phosphatidylserine, and
in phosphalidylinositol. When oleate was delivered as cholesteryl olea
te in reconstituted LDL, there was greater esterification in diacyl ph
osphatidylcholine. Third, there was a marked preference for oleate del
ivered from triolein in LDL over cholesteryl oleate in LDL for esterif
ication into the sn-1 position of plasmalogens as a vinyl ether-linked
fatty acid. These data indi cate that mode of transport of fatty acid
to cells influences fatty acid metabolism upon its incorporation into
the cell, even when the fatty acid is delivered from the core of the
same lipoprotein.