Endothelial lipase releases saturated and unsaturated fatty acids of high density lipoprotein phosphatidylcholine

Abstract

We assessed the ability of endothelial lipase (EL) to hydrolyze the sn -1 and sn -2 fatty acids (FAs) from HDL phosphatidylcholine. For this purpose, reconstituted discoidal HDLs (rHDLs) that contained free cholesterol, apolipoprotein A-I, and either 1-palmitoyl-2-oleoylphosphatidylcholine, 1-palmitoyl-2-linoleoylphosphatidylcholine, or 1-palmitoyl-2-arachidonylphosphatidylcholine were incubated with ELand control (LacZ)-conditioned media. Gas chromatography analysis of the reaction mixtures revealed that both the sn-1 (

Surface loops of extracellular phospholipase A1 determine both substrate specificity and preference for lysophospholipids

“…This idea is supported by the fact that the corresponding amino acid is valine and methionine in HL and EL, respectively ( Fig. 9B ), which also show lysophospholipase activity ( 16,17 ).…”

Suppression of endothelial or lipoprotein lipase in THP-1 macrophages attenuates proinflammatory cytokine secretion

“…Decreased expression of proinflammatory cytokines in macrophages could be ascribed to diminished lyso-PC production secondary to lipase suppression. LPL and EL are capable of hydrolyzing phospholipids, although EL has been shown to more readily hydrolyze phospholipids contained within synthetic substrates (28). The incubation of artificial phospholipid emulsion with LPL generated hydrolytic products with preference for lipolysis at the 1-acyl ester bond of phosphatidylcholine (29).…”

Acyl chain-dependent effect of lysophosphatidylcholine on endothelial prostacyclin production

“…Identifi cation of LPC 16:0, 18:1, 18:2, and 20:4 as major LPC species generated by the action of EL on HDL ( 40 ) prompted us to examine their impact on endothelial prostanoid production with the focus on PGI 2 . Whereas three studies provided evidence to support the role for 16:0 LPC as a modulator of endothelial prostanoid production ( 14, cPLA2 are used rather for reacylation of 16:0 LPC than as substrate for COX enzymes.…”

“…We demonstrated previously that EL, by cleaving HDL-PC, generates substantial amounts of LPC 16:0, 18:1, 18:2, and 20:4, respectively ( 40 ). As studies investigating the impact of LPC on prostanoid production have so far used 16:0 LPC exclusively ( 1,14,21,22 ), nothing is known about the impact of the length and degree of saturation of the LPC-acyl chain on prostanoid production.…”