Endothelial Cell Protein Targeting by Myeloperoxidase-Derived 2-Chlorofatty Aldehyde.

Neutrophils are important cellular mediators of injury and repair in diseases including ischemic heart disease, atherosclerosis, and sepsis. Myeloperoxidase-derived (MPO)-oxidants released from neutrophils are potential mediators of endothelial injury in disease. MPO-derived HOCl attacks plasmalogen phospholipid to liberate 2-chlorofatty aldehyde (2-ClFALD).

Distinct Functions of Acyl/Alkyl Dihydroxyacetonephosphate Reductase in Peroxisomes and Endoplasmic Reticulum.

Plasmalogens are a subclass of ether glycerophospholipids characterized by a vinyl-ether bond at the -1 position of the glycerol backbone. Plasmalogen biosynthesis is initiated in peroxisomes. At the third step of plasmalogen synthesis, alkyl-dihydroxyacetonephosphate (DHAP) is enzymatically reduced to 1-alkyl--glycero-3-phospate by acyl/alkyl DHAP reductase (ADHAPR), whose activity is found in both peroxisomes and microsomes.

The gene encodes plasmanylethanolamine desaturase which introduces the characteristic vinyl ether double bond into plasmalogens.

A significant fraction of the glycerophospholipids in the human body is composed of plasmalogens, particularly in the brain, cardiac, and immune cell membranes. A decline in these lipids has been observed in such diseases as Alzheimer's and chronic obstructive pulmonary disease. Plasmalogens contain a characteristic 1--alk-1'-enyl ether (vinyl ether) double bond that confers special biophysical, biochemical, and chemical properties to these lipids.

A cell-based high-throughput screen identifies tyrphostin AG 879 as an inhibitor of animal cell phospholipid and fatty acid biosynthesis.

Inhibition of animal cell phospholipid biosynthesis has been proposed for anticancer and antiviral therapies. Using CHO-K1 derived cell lines, we have developed and used a cell-based high-throughput procedure to screen a 1280 compound, small molecule library for inhibitors of phospholipid biosynthesis. We identified tyrphostin AG 879 (AG879), which inhibited phospholipid biosynthesis by 85-90% at a concentration of 10 μM, displaying an IC of 1-3 μM.

Chemical Probe to Identify the Cellular Targets of the Reactive Lipid Metabolite 2- trans-Hexadecenal.

Lipid-derived electrophiles (LDEs) are reactive metabolites, which can covalently modify proteins and DNA and regulate diverse cellular processes. 2- trans-Hexadecenal (2-HD) is a byproduct of sphingolipid metabolism, involved in cytoskeletal reorganization, DNA damage, and apoptosis. In addition, the loss of ALDH3A2, an enzyme removing 2-HD in cells, is responsible for Sjörgen-Larsson Syndrome (SJS), suggesting that accumulation of 2-HD could lead to pathogenesis.

A novel assay for the introduction of the vinyl ether double bond into plasmalogens using pyrene-labeled substrates.

Plasmanylethanolamine desaturase (PEDS) (EC 1.14.99.

The Sjögren-Larsson syndrome gene encodes a hexadecenal dehydrogenase of the sphingosine 1-phosphate degradation pathway.

Sphingosine 1-phosphate (S1P) functions not only as a bioactive lipid molecule, but also as an important intermediate of the sole sphingolipid-to-glycerolipid metabolic pathway. However, the precise reactions and the enzymes involved in this pathway remain unresolved. We report here that yeast HFD1 and the Sjögren-Larsson syndrome (SLS)-causative mammalian gene ALDH3A2 are responsible for conversion of the S1P degradation product hexadecenal to hexadecenoic acid.

Reactive oxygen species facilitate translocation of hormone sensitive lipase to the lipid droplet during lipolysis in human differentiated adipocytes.

In obesity, there is an increase in reactive oxygen species (ROS) within adipose tissue caused by increases in inflammation and overnutrition. Hormone sensitive lipase (HSL) is part of the canonical lipolytic pathway and critical for complete lipolysis. This study hypothesizes that ROS is a signal that integrates regulation of lipolysis by targeting HSL.

Glucose-6-phosphate isomerase deficiency results in mTOR activation, failed translocation of lipin 1α to the nucleus and hypersensitivity to glucose: Implications for the inherited glycolytic disease.

Inherited glucose-6-phosphate isomerase (GPI) deficiency is the second most frequent glycolytic erythroenzymopathy in humans. Patients present with non-spherocytic anemia of variable severity and with neuromuscular dysfunction. We previously described Chinese hamster (CHO) cell lines with mutations in GPI and loss of GPI activity.

Chlorinated lipid species in activated human neutrophils: lipid metabolites of 2-chlorohexadecanal.

Neutrophils are important in the host response against invading pathogens. One chemical defense mechanism employed by neutrophils involves the production of myeloperoxidase (MPO)-derived HOCl. 2-Chlorohexadecanal (2-ClHDA) is a naturally occurring lipid product of HOCl targeting the vinyl ether bond of plasmalogens.

Isolation of novel animal cell lines defective in glycerolipid biosynthesis reveals mutations in glucose-6-phosphate isomerase.

Glycerolipids are structural components for membranes and serve in energy storage. We describe here the use of a photodynamic selection technique to generate a population of Chinese hamster ovary cells that display a global deficiency in glycerolipid biosynthesis. One isolate from this population, GroD1, displayed a profound reduction in the synthesis of phosphatidylcholine, phosphatidylethanolamine, and triglycerides but presented high levels of phosphatidic acid and normal levels of phosphatidylinositol synthesis.

On the importance of plasmalogen status in stimulated arachidonic acid release in the macrophage cell line RAW 264.7.

We examined the dependence of stimulated arachidonic acid release on plasmalogens using the murine, macrophage cell line 264.7 and two plasmalogen-deficient variants, RAW.12 and RAW.

Synthesis and biological properties of the fluorescent ether lipid precursor 1-O-[9'-(1''-pyrenyl)]nonyl-sn-glycerol.

The synthesis of an omega-pyrene-labeled 1-O-alkyl-sn-glycerol was performed using a chirospecific method starting from R-(-)-2,3-O-isopropylidene-sn-glycerol. The product, 1-O-[9'-(1''-pyrenyl)]nonyl-sn-glycerol (pAG), is a fluorescent ether lipid that has a pyrene moiety covalently attached at the alkyl chain terminus. pAG was taken into CHO-K1 cells and a plasmalogen-deficient variant of CHO-K1, NRel-4.

Role of dihydroxyacetonephosphate acyltransferase in the biosynthesis of plasmalogens and nonether glycerolipids.

The variant CHO-K1 cell line, NRel-4, is unable to synthesize plasmalogens because of a severe reduction in dihydroxyacetonephosphate acyltransferase (DHAPAT) activity (Nagan, N., A. K.

Deficiency in ethanolamine plasmalogen leads to altered cholesterol transport.

Plasmalogens are a major sub-class of ethanolamine and choline phospholipids in which the sn-1 position has a long chain fatty alcohol attached through a vinyl ether bond. These phospholipids are proposed to play a role in membrane fusion-mediated events. In this study, we investigated the role of the ethanolamine plasmalogen plasmenylethanolamine (PlsEtn) in intracellular cholesterol transport in Chinese hamster ovary cell mutants NRel-4 and NZel-1, which have single gene defects in PlsEtn biosynthesis.

Increasing plasmalogen levels protects human endothelial cells during hypoxia.

Supplementation of cultured human pulmonary arterial endothelial cells (PAEC) with sn-1-O-hexadecylglycerol (HG) resulted in an approximately twofold increase in cellular levels of plasmalogens, a subclass of phospholipids known to have antioxidant properties; this was due, primarily, to a fourfold increase in the choline plasmalogens. Exposure of unsupplemented human PAEC to hypoxia (PO(2) = 20-25 mmHg) caused an increase in cellular reactive oxygen species (ROS) over a period of 5 days with a coincident decrease in viability. In contrast, HG-supplemented cells survived for at least 2 wk under these conditions with no evidence of increased ROS.