Publications

• Enzymatic synthesis of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine, a hypotensive and platelet-aggregating lipid.

  Wykle R.L., Malone B., Snyder F.

  1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine, derived chemically from choline plasmalogens of beef heart, has been shown to possess powerful antihypertensive activity (Blank, M. L., Synder, F., Byers, L. W., Brooks, B., and Muirhead, E. E. (1979) Biochem. Biophys. Res. Commun. 90, 1194-1200) and t ... >> More

  1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine, derived chemically from choline plasmalogens of beef heart, has been shown to possess powerful antihypertensive activity (Blank, M. L., Synder, F., Byers, L. W., Brooks, B., and Muirhead, E. E. (1979) Biochem. Biophys. Res. Commun. 90, 1194-1200) and to be an extremely potent platelet-activating factor (Demopoulos, C. C., Pinckard, R. N., and Hanahan, D. J. (1979) J. Biol. Chem. 254, 9355-9358). In the present study, microsomal preparations of rat spleen were shown to synthesize 1-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine by an acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase reaction; the acetyltransferase appears to be different from the acyltransferase responsible for the transfer of palmitate to glycerolipids. The apparent Km for acetyl-CoA was 67 microM; the optimal concentration of 1-alkyl-2-lyso-sn-glycero-3-phosphocholine was 30 microM. Higher concentrations of the lyso substrate were inhibitory. When acetyl-CoA (100 microM) and 1-hexadecyl-sn-glycero-3-phosphocholine (30 microM) were incubated wih spleen microsomes under optimal conditions, the specific activity was approximately 10 nmol of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine/min/mg of protein. Although the reaction was inhibited by the addition of EDTA or EGTA to the incubation mixture, the acetyltransferase did not appear to require a divalent cation. An acyl analog, 1-palmitoyl-2-lyso-sn-glycero-3-phosphocholine, also served as a substrate for the acetyltransferase; however, the unnatural isomer, 3-alkyl-2-lyso-sn-glycero-1-phosphocholine, did not. The acetyltransferase activity was found in a variety of tissues, but the spleen had the highest activity of the tissues examined; lung, lymph nodes, and thymus also had high activities. Identification of the product and the possible physiological importance of the pathway are discussed. << Less

  J Biol Chem 255:10256-10260(1980) [PubMed] [EuropePMC]

• Mammalian acyl-CoA:lysophosphatidylcholine acyltransferase enzymes.

  Soupene E., Fyrst H., Kuypers F.A.

  The mammalian RBC lacks de novo lipid synthesis but maintains its membrane composition by rapid turnover of acyl moieties at the sn-2 position of phospholipids. Plasma-derived fatty acids are esterified to acyl-CoA by acyl-CoA synthetases and transferred to lysophospholipids by acyl-CoA:lysophosph ... >> More

  The mammalian RBC lacks de novo lipid synthesis but maintains its membrane composition by rapid turnover of acyl moieties at the sn-2 position of phospholipids. Plasma-derived fatty acids are esterified to acyl-CoA by acyl-CoA synthetases and transferred to lysophospholipids by acyl-CoA:lysophospholipid acyltransferases. We report the characterization of three lysophosphatidylcholine (lysoPC) acyltransferases (LPCATs), products of the AYTL1, -2, and -3 genes. These proteins are three members of a LPCAT family, of which all three genes are expressed in an erythroleukemic cell line. Aytl2 mRNA was detected in mouse reticulocytes, and the presence of the product of the human ortholog was confirmed in adult human RBCs. The three murine Aytl proteins generated phosphatidylcholine from long-chain acyl-CoA and lysoPC when expressed in Escherichia coli membranes. Spliced variants of Aytl1, affecting a conserved catalytic motif, were identified. Calcium and magnesium modulated LPCAT activity of both Aytl1 and -2 proteins that exhibit EF-hand motifs at the C terminus. Characterization of the product of the Aytl2 gene as the phosphatidylcholine reacylating enzyme in RBCs represents the identification of a plasma membrane lysophospholipid acyltransferase and establishes the function of a LPCAT protein. << Less

  Proc. Natl. Acad. Sci. U.S.A. 105:88-93(2008) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Human lysophosphatidylcholine acyltransferases 1 and 2 are located in lipid droplets where they catalyze the formation of phosphatidylcholine.

  Moessinger C., Kuerschner L., Spandl J., Shevchenko A., Thiele C.

  Phosphatidylcholine (PC) is synthesized by two different pathways, the Lands cycle and the Kennedy pathway. The recently identified key enzymes of the Lands cycle, lysophosphatidylcholine acyltransferase 1 and 2 (LPCAT1 and -2), were reported to localize to the endoplasmic reticulum and to functio ... >> More

  Phosphatidylcholine (PC) is synthesized by two different pathways, the Lands cycle and the Kennedy pathway. The recently identified key enzymes of the Lands cycle, lysophosphatidylcholine acyltransferase 1 and 2 (LPCAT1 and -2), were reported to localize to the endoplasmic reticulum and to function in lung surfactant production and in inflammation response. Here, we show in various mammalian cell lines that both enzymes additionally localize to lipid droplets (LDs), which consist of a core of neutral lipids surrounded by a monolayer of phospholipid, mainly PC. This dual localization is enabled by the monotopic topology of these enzymes demonstrated in this study. Furthermore, we show that LDs have the ability to locally synthesize PC and that this activity correlates with the LPCAT1 and -2 expression level. This suggests that LPCAT1 and -2 have, in addition to their known function in specialized cells, a ubiquitous role in LD-associated lipid metabolism. << Less

  J. Biol. Chem. 286:21330-21339(2011) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Enzymatic activity of the human 1-acylglycerol-3-phosphate-O-acyltransferase isoform 11: upregulated in breast and cervical cancers.

  Agarwal A.K., Garg A.

  The conversion of lysophosphatidic acid (LPA) to phosphatidic acid is carried out by the microsomal enzymes 1-acylglycerol-3-phosphate-O-acyltransferases (AGPATs). These enzymes are specific for acylating LPA at the sn-2 (carbon 2) position on the glycerol backbone and are important, because they ... >> More

  The conversion of lysophosphatidic acid (LPA) to phosphatidic acid is carried out by the microsomal enzymes 1-acylglycerol-3-phosphate-O-acyltransferases (AGPATs). These enzymes are specific for acylating LPA at the sn-2 (carbon 2) position on the glycerol backbone and are important, because they provide substrates for the synthesis of phospholipids and triglycerides. At least, mutations in one isoform, AGPAT2, cause near complete loss of adipose tissue in humans. We cloned a cDNA predicted to be an AGPAT isoform, AGPAT11. This cDNA has been recently identified also as lysophosphatidylcholine acyltransferase 2 (LPCAT2) and lyso platelet-activating factor acetyltransferase. When AGPAT11/LPCAT2/lyso platelet-activating factor acetyltransferase cDNA was expressed in CHO and HeLa cells, the protein product localized to the endoplasmic reticulum. In vitro enzymatic activity using lysates of Human Embryonic Kidney-293 cells infected with recombinant AGPAT11/LPCAT2/lyso platelet-activating factor-acetyltransferase cDNA adenovirus show that the protein has an AGPAT activity but lacks glycerol-3-phosphate acyltransferase enzymatic activity. The AGPAT11 efficiently uses C18:1 LPA as acyl acceptor and C18:1 fatty acid as an acyl donor. Thus, it has similar substrate specificities for LPA and acyl-CoA as shown for AGPAT9 and 10. Expression of AGPAT11 mRNA was significantly upregulated in human breast, cervical, and colorectal cancer tissues, indicating its adjuvant role in the progression of these cancers. Our enzymatic assays strongly suggest that the cDNA previously identified as LPCAT2/lyso platelet-activating factor-acetyltransferase cDNA has AGPAT activity and thus we prefer to identify this clone as AGPAT11 as well. << Less

  J. Lipid Res. 51:2143-2152(2010) [PubMed] [EuropePMC]

  This publication is cited by 10 other entries.

• A single enzyme catalyzes both platelet-activating factor production and membrane biogenesis of inflammatory cells. Cloning and characterization of acetyl-CoA:lyso-PAF acetyltransferase.

  Shindou H., Hishikawa D., Nakanishi H., Harayama T., Ishii S., Taguchi R., Shimizu T.

  Platelet-activating factor (PAF) is a potent proinflammatory lipid mediator eliciting a variety of cellular functions. Lipid mediators, including PAF are produced from membrane phospholipids by enzymatic cascades. Although a G protein-coupled PAF receptor and degradation enzymes have been cloned a ... >> More

  Platelet-activating factor (PAF) is a potent proinflammatory lipid mediator eliciting a variety of cellular functions. Lipid mediators, including PAF are produced from membrane phospholipids by enzymatic cascades. Although a G protein-coupled PAF receptor and degradation enzymes have been cloned and characterized, the PAF biosynthetic enzyme, aceyl-CoA:lyso-PAF acetyltransferase, has not been identified. Here, we cloned lyso-PAF acetyltransferase, which is critical in stimulus-dependent formation of PAF. The enzyme is a 60-kDa microsomal protein with three putative membrane-spanning domains. The enzyme was induced by bacterial endotoxin (lipopolysaccharide), which was suppressed by dexamethasone treatment. Surprisingly, the enzyme catalyzed not only biosynthesis of PAF from lyso-PAF but also incorporation of arachidonoyl-CoA to produce PAF precursor membrane glycerophospholipids (lysophosphatidylcholine acyltransferase activity). Under resting conditions, the enzyme prefers arachidonoyl-CoA and contributes to membrane biogenesis. Upon acute inflammatory stimulation with lipopolysaccharide, the activated enzyme utilizes acetyl-CoA more efficiently and produces PAF. Thus, our findings provide a novel concept that a single enzyme catalyzes membrane biogenesis of inflammatory cells while producing a prophlogistic mediator in response to external stimuli. << Less

  J. Biol. Chem. 282:6532-6539(2007) [PubMed] [EuropePMC]

  This publication is cited by 7 other entries.

• Cloning and characterization of mouse lung-type acyl-CoA:lysophosphatidylcholine acyltransferase 1 (LPCAT1): expression in alveolar type II cells and possible involvement in surfactant production.

  Nakanishi H., Shindou H., Hishikawa D., Harayama T., Ogasawara R., Suwabe A., Taguchi R., Shimizu T.

  Phosphatidylcholine (1,2-diacyl-sn-glycero-3-phosphocholine, PC), is an important constituent of biological membranes. It is also the major component of serum lipoproteins and pulmonary surfactant. In the remodeling pathway of PC biosynthesis, 1-acyl-sn-glycero-3-phosphocholine (LPC) is converted ... >> More

  Phosphatidylcholine (1,2-diacyl-sn-glycero-3-phosphocholine, PC), is an important constituent of biological membranes. It is also the major component of serum lipoproteins and pulmonary surfactant. In the remodeling pathway of PC biosynthesis, 1-acyl-sn-glycero-3-phosphocholine (LPC) is converted to PC by acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT, EC 2.3.1.23). Whereas LPCAT activity has been detected in several tissues, the structure and detailed biochemical information on the enzyme have not yet been reported. Here, we present the cloning and characterization of a cDNA for mouse lung-type LPCAT (LPCAT1). The cDNA encodes an enzyme of 60 kDa, with three putative transmembrane domains. When expressed in Chinese hamster ovary cells, mouse LPCAT1 exhibited Ca(2+)-independent activity with a pH optimum between 7.4 and 10. LPCAT1 demonstrated a clear preference for saturated fatty acyl-CoAs, and 1-myristoyl- or 1-palmitoyl-LPC as acyl donors and acceptors, respectively. Furthermore, the enzyme was predominantly expressed in the lung, in particular in alveolar type II cells. Thus, the enzyme might synthesize phosphatidylcholine in pulmonary surfactant and play a pivotal role in respiratory physiology. << Less

  J. Biol. Chem. 281:20140-20147(2006) [PubMed] [EuropePMC]

  This publication is cited by 18 other entries.

• Molecular identification of a novel mammalian brain isoform of acyl-CoA:lysophospholipid acyltransferase with prominent ethanolamine lysophospholipid acylating activity, LPEAT2.

  Cao J., Shan D., Revett T., Li D., Wu L., Liu W., Tobin J.F., Gimeno R.E.

  Acyl-CoA-dependent lysophospholipid acyltransferases play an important role in attaining the appropriate molecular species of phospholipids. A number of genes encoding these activities were recently identified. It has become clear that multiple genes can encode one enzymatic activity and that a gi ... >> More

  Acyl-CoA-dependent lysophospholipid acyltransferases play an important role in attaining the appropriate molecular species of phospholipids. A number of genes encoding these activities were recently identified. It has become clear that multiple genes can encode one enzymatic activity and that a given gene may encode multiple activities. Here we report the identification of a gene encoding a mammalian acyl-CoA-dependent lysophospholipid acyltransferase with prominent activity toward ethanolamine-containing lysophospholipids, which we termed acyl-CoA:lysophosphatidylethanolamine acyltransferase 2, LPEAT2 (previously annotated as AYTL3 or AGPAT7). LPEAT2 is predominantly expressed in brain, coinciding with an enrichment of phosphatidylethanolamine in this tissue. Ectopic expression of LPEAT2 in mammalian HEK293T cells led to a dramatic increase (up to 9-fold) in LPEAT activity when compared with cells transfected with empty vector or an unrelated acyltransferase. LPEAT2 also exhibited significant acyl-CoA-dependent acyltransferase activity toward 1-O-alkenyl-lysophosphatidylethanolamine, lysophosphatidylglycerol, 1-O-alkyl-lysophosphatidylcholine, lysophosphatidylserine, and lysophosphatidylcholine but lacked appreciable acylating activity toward glycerol 3-phosphate, lysophosphatidic acid, lysophosphatidylinositol, and diacylglycerol, demonstrating multiple but selective functions of LPEAT2 as an enzyme involved in phospholipid remodeling. LPEAT2 recognizes a broad range of medium and long chain fatty acyl-CoA, and its activity was not affected by Ca(2+). When overexpressed in mammalian cells, LPEAT2 is localized to the endoplasmic reticulum. siRNA-mediated knockdown of LPEAT2 in HEK293T cells significantly decreased LPEAT and 1-alkenyl-LPEAT activities but did not affect other lysophospholipid acylating activities. These findings identify LPEAT2 as an important enzyme in the biosynthesis of ethanolamine-containing phospholipids, especially in brain. << Less

  J. Biol. Chem. 283:19049-19057(2008) [PubMed] [EuropePMC]

  This publication is cited by 18 other entries.