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O'Donnell VB. New appreciation for an old pathway: the Lands Cycle moves into new arenas in health and disease. Biochem Soc Trans 2022; 50:1-11. [PMID: 35225335 PMCID: PMC9022965 DOI: 10.1042/bst20210579] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 02/15/2022] [Accepted: 02/15/2022] [Indexed: 02/08/2023]
Abstract
The Lands Pathway is a fundamental biochemical process named for its discovery by William EM Lands and revealed in a series of seminal papers published in the Journal of Biological Chemistry between 1958-65. It describes the selective placement in phospholipids of acyl chains, by phospholipid acyltransferases. This pathway has formed a core component of our knowledge of phospholipid and also diglyceride metabolism in mammalian tissues for over 60 years now. Our understanding of how the Lands pathways are enzymatically mediated via large families of related gene products that display both substrate and tissue specificity has grown exponentially since. Recent studies building on this are starting to reveal key roles for the Lands pathway in specific scenarios, in particular inflammation, immunity and inflammation. This review will cover the Lands cycle from historical perspectives first, then present new information on how this important cycle forms a central regulatory node connecting fatty acyl and phospholipid metabolism and how its altered regulation may present new opportunities for therapeutic intervention in human disease.
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Affiliation(s)
- Valerie B. O'Donnell
- Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4SN, U.K
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Yamashita A, Hayashi Y, Matsumoto N, Nemoto-Sasaki Y, Koizumi T, Inagaki Y, Oka S, Tanikawa T, Sugiura T. Coenzyme-A-Independent Transacylation System; Possible Involvement of Phospholipase A2 in Transacylation. BIOLOGY 2017; 6:biology6020023. [PMID: 28358327 PMCID: PMC5485470 DOI: 10.3390/biology6020023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 11/29/2022]
Abstract
The coenzyme A (CoA)-independent transacylation system catalyzes fatty acid transfer from phospholipids to lysophospholipids in the absence of cofactors such as CoA. It prefers to use C20 and C22 polyunsaturated fatty acids such as arachidonic acid, which are esterified in the glycerophospholipid at the sn-2 position. This system can also acylate alkyl ether-linked lysophospholipids, is involved in the enrichment of arachidonic acid in alkyl ether-linked glycerophospholipids, and is critical for the metabolism of eicosanoids and platelet-activating factor. Despite their importance, the enzymes responsible for these reactions have yet to be identified. In this review, we describe the features of the Ca2+-independent, membrane-bound CoA-independent transacylation system and its selectivity for arachidonic acid. We also speculate on the involvement of phospholipase A2 in the CoA-independent transacylation reaction.
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Affiliation(s)
- Atsushi Yamashita
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Yasuhiro Hayashi
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Naoki Matsumoto
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Yoko Nemoto-Sasaki
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Takanori Koizumi
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Yusuke Inagaki
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Saori Oka
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Takashi Tanikawa
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
| | - Takayuki Sugiura
- Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-Ku, Tokyo 173-8605, Japan.
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Acyltransferases and transacylases that determine the fatty acid composition of glycerolipids and the metabolism of bioactive lipid mediators in mammalian cells and model organisms. Prog Lipid Res 2014; 53:18-81. [DOI: 10.1016/j.plipres.2013.10.001] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 07/20/2013] [Accepted: 10/01/2013] [Indexed: 12/21/2022]
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4
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Tomita M, Baker RC, Ando S, Santoro TJ. Arachidonoyl-phospholipid remodeling in proliferating murine T cells. Lipids Health Dis 2004; 3:1. [PMID: 14754461 PMCID: PMC343295 DOI: 10.1186/1476-511x-3-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Accepted: 01/30/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Previous studies have shown that the functional capacity of T cells may be modulated by the composition of fatty acids within, and the release of fatty acids from membrane phospholipids, particularly containing arachidonic acid (AA). The remodeling of AA within membrane phospholipids of resting and proliferating CD4+ and CD8+ T cells is examined in this study. RESULTS Splenic T cells were cultured in the presence or absence of anti-CD3 mAb for 48 h then labeled with [3H]AA for 20 min. In unstimulated cells, labeled AA was preferentially incorporated into the phosphoglycerides, phosphatidylcholine (PC) followed by phosphatidylinositol (PI) and phosphatidylethanolamine (PE). During a subsequent chase in unlabeled medium unstimulated CD4+ and CD8+ T cells demonstrated a significant and highly selective transfer of free, labeled AA into the PC pool. In contrast, proliferating CD4+ and CD8+ T cells distributed labeled [3H]AA predominantly into PI followed by PC and PE. Following a chase in AA-free medium, a decline in the content of [3H]AA-PC was observed in association with a comparable increase in [3H]AA-PE. Subsequent studies revealed that the cold AA content of all PE species was increased in proliferating T cells compared with that in non-cycling cells, but that enrichment in AA was observed only in the ether lipid fractions. Finally, proliferating T cells preincubated with [3H]AA exhibited a significant loss of labeled arachidonate in the PC fraction and an equivalent gain in labeled AA in 1-alk-1'-enyl-2-arachidonoyl-PE during a chase in unlabeled medium. CONCLUSION This apparent unidirectional transfer of AA from PC to ether-containing PE suggests the existence of a CoA-independent transacylase system in T cells and supports the hypothesis that arachidonoyl phospholipid remodeling may play a role in the regulation of cellular proliferation.
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Affiliation(s)
- Michiyo Tomita
- Departments of Internal Medicine, University of North Dakota, Grand Forks, ND 58203, USA
| | - Rodney C Baker
- Department of Pharmacology & Toxicology, University of Mississippi, Jackson, MS 39216. USA
| | - Soichiro Ando
- Department of Medicine, Juntendo University, Tokyo, Japan
| | - Thomas J Santoro
- Departments of Internal Medicine, University of North Dakota, Grand Forks, ND 58203, USA
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Samples BL, Pool GL, Lumb RH. Subcellular localization of enzyme activities involved in the metabolism of platelet-activating factor in rainbow trout leukocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1437:357-66. [PMID: 10101269 DOI: 10.1016/s1388-1981(99)00030-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The subcellular distribution of an alkyllyso-GPC: acetyl-CoA acetyltransferase (EC 2.3.1.67) and transacylase, two important enzyme activities involved in the remodeling pathway for the biosynthesis of platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, PAF) have been examined in leukocytes isolated from the pronephros of the rainbow trout, Oncorhynchus mykiss. Contrary to mammalian systems, in which the acetyltransferase is localized to intracellular membranes, the subcellular distribution of an acetyltransferase activity in rainbow trout leukocytes was localized to the plasma membrane. Analysis of the acetyltransferase products by thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC) confirmed synthesis of two subclasses of PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine and 1-acyl-2-acetyl-sn-glycero-3-phosphocholine. The transacylase activity in this study was detected in membrane fractions in two domains of the intermediate density region which also contained the NADH dehydrogenase activity, a marker enzyme for the endoplasmic reticulum. Acylation of lysoPAF (1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine) exhibited approximately 95% specificity for omega-3 fatty acids. Acylation patterns were not significantly different in either domain of the endoplasmic reticulum. A model is proposed herein for the metabolism of PAF in rainbow trout leukocytes.
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Affiliation(s)
- B L Samples
- Mountain Aquaculture Research Center, Western Carolina University, Cullowhee, NC 28723, USA.
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Frenkel RA, Muguruma K, Johnston JM. The biochemical role of platelet-activating factor in reproduction. Prog Lipid Res 1996; 35:155-68. [PMID: 8944225 DOI: 10.1016/0163-7827(96)00002-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The presence of Co-A independent transacylase activity in amnion cells and the preferential transfer of arachidonic acid to acceptor-ethanolamine plasmalogen provide a satisfactory explanation to the questions raised by the observation that arachidonate-enriched ethanolamine plasmalogen increases in amnion late in gestation without alteration in the total amount of ethanolamine glycerophospholipids. The proposed mechanism also serves as a link between the observed changes in glycerophospholipid composition and the generation of PAF. We have emphasized a role for PAF in fetal lung maturation, the initiation and maintenance of parturition, and in certain complications associated with a premature delivery. Although PAF is known to be the most potent lipid mediator yet described and its importance in reproductive biology is well documented, it is our view that these events cannot be attributed solely to PAF and in all likelihood a number of autacoids participate in these processes.
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Affiliation(s)
- R A Frenkel
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9051, USA
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7
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Nixon AB, Greene DG, Wykle RL. Comparison of acceptor and donor substrates in the CoA-independent transacylase reaction in human neutrophils. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1300:187-96. [PMID: 8679683 DOI: 10.1016/0005-2760(96)00011-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In human neutrophils (PMN) the ethanolamine-containing phosphoglyceride fraction (PE), principally plasmalogen-linked PE (1-O-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine), is the major store of arachidonic acid (AA). Exogenous AA is initially incorporated into 1-acyl-linked phosphoglycerides and is believed to be transferred into the 1-ether-linked phosphoglycerides via the action of a CoA-independent transacylase (CoA-IT). We have investigated the selectivity for both the "acceptor' lysophospholipids and "donor' AA-containing phospholipid substrates in the CoA-IT reaction. Evidence suggests CoA-IT may also participate in the synthesis of platelet activating factor. The transfer of [3H]AA from endogenously labeled choline-containing phosphoglycerides (PC) to exogenously added alkenyl-lyso-PE (0-50 microM) was examined in saponin-permeabilized PMN. In these "donor' studies, we observed that [3H]AA was transferred from both alkyl- and diacyl-linked PC in a proportional manner. More detailed molecular species analysis showed that [3H]AA was deacylated from all the major AA-containing molecular species in both the alkyl and diacyl subclasses with no selectivity for either subclass. To investigate the "acceptor' selectivity, membrane fractions prelabeled with either [3H]alkyl-arachidonoyl-PE or -PC were utilized as donor substrates. Various unlabeled lysophospholipids (10 microM) were added and the generation of [3H]lyso-PE or -PC was monitored as a measure of CoA-IT activity. Significant subclass preference was observed upon addition of lyso-PE species (1-alkenyl > 1-alkyl > 1-acyl) however, little selectivity was seen with the corresponding lyso-PC species. On the other hand, lysophosphatidylserine, lysophosphatidylinositol, and lysophosphatidic acid all served as poor acceptor substrates in the reaction. These data from PMN are consistent with other evidence that the CoA-IT plays a pivotal role in the enrichment of AA into plasmalogen-linked PE.
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Affiliation(s)
- A B Nixon
- Department of Biochemistry, Bowman Gray School of Medicine, Winston-Salem, NC 27157-1016, USA
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8
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Yamashita A, Sato K, Watanabe M, Tokudome Y, Sugiura T, Waku K. Induction of coenzyme A-dependent transacylation activity in rat liver microsomes by administration of clofibrate. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1211:263-9. [PMID: 8130258 DOI: 10.1016/0005-2760(94)90149-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effect of administration of clofibrate on the activity of coenzyme A-dependent (CoA-dependent) transacylation of 1-acyl-glycerophosphocholine (1-acyl-GPC) was examined in rat liver microsomes. Administration of clofibrate to rats increased the activity of Co-A-dependent transacylation of 1-[14C]acyl-GPC and the activity reached a value (8.37 nmol/min per mg protein) twice that in control rats (3.95 nmol/min per mg protein) without any changes in apparent Km values for CoA (1.2 microM in control and 1.0 microM in clofibrate-treated) and 1-acyl-GPC (33.4 microM in control and 27.8 microM in clofibrate-treated). The rate of CoA-dependent transfer of [14C]arachidonic acid (20:4) from 1-acyl-2-[14C]20:4-glycerophosphoethanolamine (GPE) or 1-acyl-2-[14C]20:4-glycerophosphoinositol (GPI) to 1-acyl-GPC (synthesis of 1-acyl-2-[14C]20:4-GPC) was also increased by treatment with clofibrate (1.9-fold and 1.5-fold increases, respectively). These results suggest that a CoA-dependent transacylation system of 1-acyl-GPC was induced by treatment with clofibrate.
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Affiliation(s)
- A Yamashita
- Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan
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9
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Affiliation(s)
- F Snyder
- Medical Sciences Division, Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, TN 37831-0117, USA
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10
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Lehner R, Kuksis A. Triacylglycerol synthesis by an sn-1,2(2,3)-diacylglycerol transacylase from rat intestinal microsomes. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)52942-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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11
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Jansen GJ, Pritzker CR, Deykin D. Porcine aortic endothelial cell membranes contain a LPAF: CoA-independent transacylase. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1145:113-8. [PMID: 8422403 DOI: 10.1016/0005-2736(93)90387-f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Membranes isolated from porcine aortic endothelial cells (PAEC) contain a CoA-independent transacylase enzyme (CoA-IT). CoA-IT, an integral membrane protein, transfers an acyl moiety to added [3H]alkylhydroxyglycerophosphocholine (LPAF) to generate [3H]alkylacylglycerophosphocholine (alkylacyl-GPC). This enzyme exhibits an apparent Km of 0.7 microM and a Vmax of 0.8 nmol/min per mg for the transfer of an acyl group to added [3H]LPAF. The addition of the nonionic detergent Triton X-100 (TX-100) (0.5 mg/ml), the sulfhydryl reagents N-ethylmaleimide (NEM) (200 microM) or thimerosal (200 microM), or pre-incubating the membranes at 95 degrees C for 10 min all decreased LPAF: CoA-IT activity by more than 95%. The inhibitory action of NEM or thimerosal suggests that sulfhydryl group(s) are involved in or are close to the catalytic site of LPAF: CoA-IT.
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Affiliation(s)
- G J Jansen
- Department of Medicine and Biochemistry, Boston University School of Medicine, MA
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12
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13
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Snyder F, Lee TC, Blank ML. The role of transacylases in the metabolism of arachidonate and platelet activating factor. Prog Lipid Res 1992; 31:65-86. [PMID: 1641397 DOI: 10.1016/0163-7827(92)90016-c] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- F Snyder
- Oak Ridge Associated Universities, Medical Sciences Division, TN 37831-0117
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14
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Sugiura T, Ojima-Uchiyama A, Masuzawa Y, Fujita M, Nakagawa Y, Waku K. Regulation of the biosynthesis of platelet-activating factor in alveolar macrophages. Lipids 1991; 26:974-8. [PMID: 1819752 DOI: 10.1007/bf02536487] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Activities of enzymes which metabolize lysoplatelet-activating factor (lysoPAF) and platelet-activating factor (PAF) were studied in rabbit alveolar macrophage lysates. Substantial acetyltransferase activity was noted in the presence of 100 microM acetyl-coenzyme A (CoA), and this activity was increased in A23187-stimulated cell lysate. On the other hand, in the absence of exogenous acetyl-CoA, lysoPAF was mainly acylated through a transacylation pathway rather than by acetyltransferase in both control and A23187-stimulated cell lysates. We confirmed that the intracellular concentration of acetyl-CoA is relatively low. The observations suggest that the transacylation system may play an equally important role in the regulation of the availability of lysoPAF in intact cells. Intracellular lysoPAF was also maintained at relatively low levels. Interestingly, large amounts of PAF were produced even in unstimulated cells upon addition of an excess of exogenous lysoPAF, suggesting that generation of an adequate amount of lysoPAF within cells may be sufficient to trigger PAF synthesis in this type of cells.
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan
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15
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Lee TC, Blank ML, Fitzgerald V, Snyder F. Acylation of alkyllysophospholipids by Fischer sarcoma microsomes. Arch Biochem Biophys 1991; 288:600-8. [PMID: 1898052 DOI: 10.1016/0003-9861(91)90242-b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Acylation of alkyllysophospholipids in most cells occurs by: (a) CoA-independent transacylation, (b) CoA-dependent transacylation, and (c) acyl-CoA-dependent acylation. Using a recently developed high-performance liquid chromatography method, we have investigated the factors that influence the molecular species composition of the acylated products formed via these pathways with 1-hexadecyl-2-lyso-sn-glycero-3-phosphocholine (alkyllyso-GPC) or 1-hexadecyl-2-lyso-sn-glycero-3-phospho-ethanolamine (alkyllyso-GPE) as substrates for the enzymes in Fischer R-3259 sarcoma microsomes. We found that short incubation times and low substrate concentrations favored the formation of polyunsaturated molecular species, i.e., 16:0-22:6, 16:0-22:5 (n - 3), and 16:0-20:4. Also, in agreement with results from other systems, CoA-independent transacylation produced a high percentage of polyunsaturated molecular species; acyl-CoA-dependent acylations generated the least polyunsaturated molecular species and CoA-dependent transacylation gave intermediate values. Furthermore, no substrate selectivity occurred with respect to alkyl chain lengths of alkyllyso-GPE; similar molecular species composition was obtained with either hexadecyllyso-GPE or octadecyllyso-GPE as substrates. Responses to N-ethylmaleimide inhibition and heat inactivation as well as pH optima suggest the same enzyme catalyzes the CoA-independent transacylation of both alkyllyso-GPC and alkyllyso-GPE.
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Affiliation(s)
- T C Lee
- Medical Sciences Division, Oak Ridge Associated Universities, Tennessee 37831-0117
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MacDonald JI, Sprecher H. Phospholipid fatty acid remodeling in mammalian cells. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1084:105-21. [PMID: 1854795 DOI: 10.1016/0005-2760(91)90209-z] [Citation(s) in RCA: 247] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- J I MacDonald
- Department of Medical Biochemistry, Ohio State University, Columbus 43210
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17
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Thomas SE, Byers DM, Palmer FB, Spence MW, Cook HW. Incorporation of polyunsaturated fatty acids into plasmalogens, compared to other phospholipids of cultured glioma cells, is more dependent on chain length than on selectivity between (n - 3) and (n - 6) families. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1044:349-56. [PMID: 2364099 DOI: 10.1016/0005-2760(90)90079-d] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In several tissues and cells, polyunsaturated fatty acids (PUFA) are esterified to plasmalogens (1-O-alk-1'-enyl-2-acyl-sn-glycero-3 phosphoethanolamine). Some studies have implicated selectivity for (n - 3) fatty acids, particularly of 20- and 22-carbons, over the (n - 6) family of fatty acids. We have investigated selectivity for esterification of both families of PUFA to plasmalogens in cultured C6 glioma cells. By 24 h, approx. 40% of cell-associated label from [1-14C]18:3(n - 3) was incorporated into plasmalogens and that label consisted almost exclusively of desaturation and chain elongation products [80% 20:5(n - 3) and 15% 22:5(n - 3)]. Relative incorporation of label from PUFA into plasmalogens was 20:5(n - 3) greater than 20:4(n - 6) greater than 18:3(n - 3) much greater than 18:2(n - 6); incorporation of unaltered 18-carbon chains was highly restricted. Cells incubated with [1-14C]18:3(n - 3) and 20-150 microM competing unlabeled fatty acids showed 20:5(n - 3) greater than 20:4(n - 6) greater than or equal to 22:4(n - 6) greater than 18:3(n - 3) as inhibitors of plasmalogen labeling. Chase experiments in cells prelabeled with [1-14C]18:3(n - 3) for 2 h showed limited reduction of label in plasmalogen. Reduction of plasmalogen label did occur when (n - 3) or (n - 6) fatty acids were added to cells prelabeled for 48 h, accounting for losses of 20-35% compared to controls. Accordingly, little selectivity occurs in esterification of plasmalogens from mixtures of (n - 3) and (n - 6) fatty acyl chains. Subsequent remodeling of (n - 3) acyl chains occurs, but is more dependent on acyl chain length than on selectivity between (n - 3) and (n - 6) families. Our data are consistent with a stable plasmalogen pool enriched in PUFA, but not specifically with (n - 3) fatty acids.
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Affiliation(s)
- S E Thomas
- Department of Pediatrics, Dalhousie University, Halifax, Canada
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18
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Masuzawa Y, Okano S, Waku K, Sprecher H, Lands WE. Selective incorporation of various C-22 polyunsaturated fatty acids in Ehrlich ascites tumor cells. J Lipid Res 1990. [DOI: 10.1016/s0022-2275(20)38750-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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19
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Snyder F, Lee TC, Blank ML. Platelet-activating factor and related ether lipid mediators. Biological activities, metabolism, and regulation. Ann N Y Acad Sci 1989; 568:35-43. [PMID: 2698076 DOI: 10.1111/j.1749-6632.1989.tb12488.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- F Snyder
- Medical Sciences Division, Oak Ridge Associated Universities, Tennessee 37831-0117
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20
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Weber PC. Clinical studies on the effects of n-3 fatty acids on cells and eicosanoids in the cardiovascular system. JOURNAL OF INTERNAL MEDICINE. SUPPLEMENT 1989; 731:61-8. [PMID: 2650699 DOI: 10.1111/j.1365-2796.1989.tb01437.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Epidemiological, clinical and experimental studies suggest that dietary fatty acids belonging to two different families, the n-6 and n-3 fatty acids, might be important nutritional factors contributing to the natural history of atherothrombotic and inflammatory disorders. The relationship of these dietary fatty acids to plasma and cell membrane phospholipid composition, the eicosanoid system and related lipid mediators, and the mechanisms involved in cell stimulus-response coupling (such as phospholipase C and phospholipase A2 activation and Ca2+ release) might reveal and modify processes underlying those disorders. It may thus open the development of new approaches to prevention and therapy.
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Affiliation(s)
- P C Weber
- Institut für Prophylaxe und Epidemiologie der Kreislaufkrankheiten, Universität München, FRG
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21
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Triggiani M, Chilton FH. Influence of immunologic activation and cellular fatty acid levels on the catabolism of platelet-activating factor within the murine mast cell (PT-18). BIOCHIMICA ET BIOPHYSICA ACTA 1989; 1006:41-51. [PMID: 2572273 DOI: 10.1016/0005-2760(89)90321-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The present study has examined the catabolism of 1-O-[3H]hexadecyl-2-acetyl-GPC (C16-PAF) and of 1-O-octadecyl-2-acetyl-GPC (C18-PAF) in spleen-derived PT-18 murine mast cells (mast cells). Mast cells catabolized exogenous PAF into two inactive metabolites, 1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine (lysoPAF) and 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine (1-O-alkyl-2-acyl-GPC). The rate of conversion of C16-PAF to metabolites was more rapid than that of C18-PAF. Analysis of the acyl composition of 1-O-alkyl-2-acyl-GPC formed during the metabolism of PAF revealed that arachidonic acid (20:4) was the major fatty acyl chain incorporated at the sn-2 position. However, 25% of newly formed 1-O-alkyl-2-acyl-GPC was reacylated with docosahexaenoic acid (22:6). The influence of cellular fatty acid content on PAF catabolism was further explored in mast cells in which the ratio of fatty acids within cellular phosphoglycerides had been altered by supplementing the cells with various fatty acids in culture. Mast cells supplemented with 20:4 or 22:6 converted PAF to 1-O-alkyl-2-acyl-GPC at a significantly higher rate than non-supplemented cells. In contrast, cells supplemented with linoleic acid (18:2) metabolized PAF at rates similar to non-supplemented cells. Analysis of the acyl composition of 1-O-alkyl-2-acyl-GPC derived from the metabolism of PAF in 20:4-supplemented cells indicated that 20:4 was incorporated exclusively into the sn-2 position. Conversely, 22:6-supplemented cells incorporated predominantly 22:6 at the sn-2 position of 1-alkyl-2-lyso-GPC. Supplementation with 18:2 had no effect on the acylation pattern seen in newly formed 1-O-alkyl-2-acyl-GPC. Activation of passively sensitized mast cells with antigen or with ionophore A23187 significantly enhanced the rate of catabolism of exogenously-provided PAF but had no effect on the acylation pattern of 1-O-alkyl-2-acyl-GPC. Experiments performed with the soluble fraction of the cells showed that acetyl hydrolase activity was increased in mast cells stimulated with antigen. In addition, supernatant fluids from antigen or ionophore-treated mast cells converted PAF to lysoPAF, suggesting that acetyl hydrolase activity was released during cell activation. These data indicate that the ability of mast cells to catabolize PAF to inactive metabolites is influenced by cell activation and by the cellular levels of certain fatty acids.
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Affiliation(s)
- M Triggiani
- Department of Medicine, Johns Hopkins University School of Medicine, Good Samaritan Hospital, Baltimore, MD 21239
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Distribution of arachidonic acid in choline- and ethanolamine-containing phosphoglycerides in subfractionated human neutrophils. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84630-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Arthur G, Page L, Choy PC. Acylation of 1-alkenylglycerophosphoethanolamine and 1-acylglycerophosphoethanolamine in guinea-pig heart microsomes. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 921:259-65. [PMID: 3651487 DOI: 10.1016/0005-2760(87)90026-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Although the acylation of 1-alkenylglycerophosphocholine in mammalian heart is well documented, the acylation of 1-alkenylglycerophosphoethanolamine in the heart was not reported. In this study, the presence of acyl CoA: 1-alkenylglycerophosphoethanolamine acyltransferase in the guinea pig heart microsomes was demonstrated. 1-Alkenylglycerophosphoethanolamine acyltransferase displayed a high degree of specificity towards acyl-CoA. The order of reactivity with acyl-CoA was found to be: linoleoyl much greater than arachidonyl greater than palmitoyl greater than stearoyl = oleoyl. 1-Acylglycerophosphoethanolamine acyltransferase in the microsomes also exhibited specificity towards acyl-CoA in the following manner: linoleoyl greater than arachidonyl much greater than palmitoyl greater than oleoyl greater than stearoyl. However, such specificity appeared to be dependent on acyl-CoA concentration. The acyl-CoA specificities of both enzymes did not correlate with the C-2 acyl distribution observed in the corresponding microsomal phospholipids. Our results suggest that in addition to the acyl specificity of the acyltransferases, intracellular concentrations of acyl-CoAs may also have an important role in determining the observed acyl patterns of the phospholipids. Based on the acyl specificities, pH profiles, and their responses to heat inactivation and thiol reagents, we conclude that 1-alkenylglycerophosphoethanolamine acyltransferase and 1-acylglycerophosphoethanolamine acyltransferase in guinea-pig heart microsomes are not the same enzyme.
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Affiliation(s)
- G Arthur
- Department of Biochemistry, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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Sugiura T, Sekiguchi N, Nakagawa Y, Waku K. Formation of diacyl and alkylacyl glycerophosphocholine in rabbit alveolar macrophages. Lipids 1987; 22:589-95. [PMID: 3657397 DOI: 10.1007/bf02537286] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The incorporation of various labeled precursors into alkenylacyl, alkylacyl and diacyl phospholipids in rabbit alveolar macrophages was studied. The incorporation rates of the individual precursors were shown to be quite different among the three subclasses of phospholipids. [3H]Glycerol, [14C]16:0, [14C]18:1, [14C]18:2 and [32P]-orthophosphate were preferentially incorporated into choline glycerophospholipids (CGP), especially into diacyl glycerophosphocholine (GPC), indicating that the de novo synthesis of diacyl GPC is extremely high. Considerable portions of the radioactivities of [14C]16:0, [14C]18:1, [14C]18:2 and [32P]orthophosphate were also found in alkylacyl GPC, the incorporation being higher than or comparable to that in the case of diacyl glycerophosphoethanolamine (GPE). We then examined the activities of cholinephosphotransferase and ethanol-aminephosphotransferase, and found that the activity of cholinephosphotransferase was remarkably high in macrophage microsomes compared with that in microsomes from several other tissues. This suggests that diradylglycerols were preferentially utilized by choline-phosphotransferase, which is consistent with the results obtained for intact cells. We confirmed that a considerably higher amount of diacyl GPC as well as alkylacyl GPC was formed through this enzyme reaction with macrophage microsomes than with brain microsomes. The high formation of alkylacyl GPC could be responsible, at least in part, for the accumulation of this unique ether phospholipid, a stored precursor form of platelet-activating factor in macrophages.
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan
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Ojima A, Nakagawa Y, Sugiura T, Masuzawa Y, Waku K. Selective transacylation of 1-O-alkylglycerophosphoethanolamine by docosahexaenoate and arachidonate in rat brain microsomes. J Neurochem 1987; 48:1403-10. [PMID: 2951496 DOI: 10.1111/j.1471-4159.1987.tb05678.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The mechanism involved in the enzymic acylation of 1-[3H]alkylglycero-3-phosphoethanolamine (1-[3H]alkyl-GPE) in brain microsomes was investigated in comparison with the acylation of 1-[3H]alkylglycero-3-phosphocholine (1-[3H]alkyl-GPC). Both the alkyllsophospholipids were acylated without exogenously added cofactors to similar extents. The [14C]arachidonoyl moiety of exogenously added 1-stearoyl-2-[14C]arachidonoyl-GPC was transferred to the alkyllysophospholipids and the transfer was not inhibited by exogenously added free arachidonate. These results indicated that the transferase activity was due to a transacylase that catalyzes the transfer of fatty acids between intact phospholipids. The addition of CoA increased the acylation of 1-[3H]alkyl-GPC two or three times with a high acceptor concentration, and the highest rate of acylation of 1-[3H]alkyl-GPC was observed in the presence of CoA, ATP, and Mg2+. On the other hand, the addition of such cofactors only slightly increased the acylation of 1-[3H]alkyl-GPE. HPLC analysis revealed that docosahexaenoate and arachidonate were transferred to the second position of both [3H]alkyllysophospholipids without cofactors and that other fatty acids were transferred to much lower extents. With the addition of cofactors, the acylation of 1-[3H]alkyl-GPC by both docosahexaenoate and arachidonate increased 1.5-2 times, and high amounts of palmitate, oleate, and linoleate were newly transferred. High amounts of oleate were also transferred to 1-[3H]alkyl-GPE in the presence of cofactors but the acylation by both docosahexaenoate and arachidonate scarcely increased on the addition of these cofactors.(ABSTRACT TRUNCATED AT 250 WORDS)
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Sugiura T, Masuzawa Y, Nakagawa Y, Waku K. Transacylation of lyso platelet-activating factor and other lysophospholipids by macrophage microsomes. Distinct donor and acceptor selectivities. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75771-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Blank ML, Lee TC, Cress EA, Fitzgerald V, Snyder F. Plasmalogen biosynthesis in Madin-Darby canine kidney cells: selectivity in the acylation of 1-alkyl-2-lyso-sn-glycero-3-phosphoethanolamine and the subsequent desaturation step. Arch Biochem Biophys 1986; 251:55-60. [PMID: 3789745 DOI: 10.1016/0003-9861(86)90050-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Acyl group specificity in the acylation of 1-alkyl-2-lyso-sn-glycero-3-phosphoethanolamine (1-alkyl-2-lyso-GroPEtn) to form 1-alkyl-2-acyl-sn-glycero-3-phosphoethanolamine (1-alkyl-2-acyl-GroPEtn) and the subsequent desaturation of 1-alkyl-2-acyl-GroPEtn to form plasmalogens (1-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine, i.e., 1-alk-1'-enyl-2-acyl-GroPEtn) was investigated in intact Madin-Darby canine kidney (MDCK) cells and cell-free membrane preparations. We found 1-[3H]alkyl-2-lyso-GroPEtn was selectively acylated with polyunsaturated fatty acids in the order 20:4 greater than 20:5 greater than 20:3 (n-9) greater than 22:6 by cell-free membrane preparations of MDCK cells. The same pattern of acyl specificity was seen in intact MDCK cells, although the intact cells produced significantly larger amounts of 1-[3H]alkyl-2-acyl-GroPEtn containing oleic acid. There was an increased desaturation of the 1-[3H]alkyl-2-acyl-GroPEtn species containing docosahexaenoic acid to plasmalogens (1-[3H]alk-1'-enyl-2-acyl-GroPEtn) by both intact MDCK cells and the cell-free membrane preparations. The relatively rapid disappearance of the 1-[3H]alk-1'-enyl-2-docosahexaenoyl-GroPEtn species during a 20-h incubation of prelabeled intact MDCK cells suggests a more rapid turnover of this molecular species. Our results indicate there is a high selectivity in the final acylation and desaturation steps of the biosynthetic pathway for plasmalogens.
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