1
|
Gupta G, Kaur J, Bhattacharya K, Chambers BJ, Gazzi A, Furesi G, Rauner M, Fuoco C, Orecchioni M, Delogu LG, Haag L, Stehr JE, Thomen A, Bordes R, Malmberg P, Seisenbaeva GA, Kessler VG, Persson M, Fadeel B. Exploiting Mass Spectrometry to Unlock the Mechanism of Nanoparticle-Induced Inflammasome Activation. ACS NANO 2023; 17:17451-17467. [PMID: 37643371 PMCID: PMC10510732 DOI: 10.1021/acsnano.3c05600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 08/21/2023] [Indexed: 08/31/2023]
Abstract
Nanoparticles (NPs) elicit sterile inflammation, but the underlying signaling pathways are poorly understood. Here, we report that human monocytes are particularly vulnerable to amorphous silica NPs, as evidenced by single-cell-based analysis of peripheral blood mononuclear cells using cytometry by time-of-flight (CyToF), while silane modification of the NPs mitigated their toxicity. Using human THP-1 cells as a model, we observed cellular internalization of silica NPs by nanoscale secondary ion mass spectrometry (nanoSIMS) and this was confirmed by transmission electron microscopy. Lipid droplet accumulation was also noted in the exposed cells. Furthermore, time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed specific changes in plasma membrane lipids, including phosphatidylcholine (PC) in silica NP-exposed cells, and subsequent studies suggested that lysophosphatidylcholine (LPC) acts as a cell autonomous signal for inflammasome activation in the absence of priming with a microbial ligand. Moreover, we found that silica NPs elicited NLRP3 inflammasome activation in monocytes, whereas cell death transpired through a non-apoptotic, lipid peroxidation-dependent mechanism. Together, these data further our understanding of the mechanism of sterile inflammation.
Collapse
Affiliation(s)
- Govind Gupta
- Institute
of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Jasreen Kaur
- Institute
of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Kunal Bhattacharya
- Institute
of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
| | | | - Arianna Gazzi
- Department
of Biomedical Sciences, University of Padua, Padua 35121, Italy
| | - Giulia Furesi
- Department
of Medicine III and Center for Healthy Aging, TU Dresden, 01307 Dresden, Germany
| | - Martina Rauner
- Department
of Medicine III and Center for Healthy Aging, TU Dresden, 01307 Dresden, Germany
| | - Claudia Fuoco
- Department
of Biology, University of Rome Tor Vergata, Rome 00173, Italy
| | - Marco Orecchioni
- Division
of Inflammation Biology, La Jolla Institute
for Immunology, La Jolla, California 92037, United States
| | - Lucia Gemma Delogu
- Department
of Biomedical Sciences, University of Padua, Padua 35121, Italy
| | - Lars Haag
- Department
of Laboratory Medicine, Karolinska Institutet, 141 52 Huddinge, Sweden
| | - Jan Eric Stehr
- Department
of Physics, Chemistry and Biology, Linköping
University, 581 83 Linköping, Sweden
| | - Aurélien Thomen
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, 412 96 Göteborg, Sweden
| | - Romain Bordes
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 412 96 Göteborg, Sweden
| | - Per Malmberg
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 412 96 Göteborg, Sweden
| | - Gulaim A. Seisenbaeva
- Department
of Molecular Sciences, Swedish University
of Agricultural Sciences, 750 07 Uppsala, Sweden
| | - Vadim G. Kessler
- Department
of Molecular Sciences, Swedish University
of Agricultural Sciences, 750 07 Uppsala, Sweden
| | - Michael Persson
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 412 96 Göteborg, Sweden
| | - Bengt Fadeel
- Institute
of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
| |
Collapse
|
2
|
Hayashi D, Dennis EA. Molecular basis of unique specificity and regulation of group VIA calcium-independent phospholipase A 2 (PNPLA9) and its role in neurodegenerative diseases. Pharmacol Ther 2023; 245:108395. [PMID: 36990122 PMCID: PMC10174669 DOI: 10.1016/j.pharmthera.2023.108395] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/21/2023] [Accepted: 03/22/2023] [Indexed: 03/29/2023]
Abstract
Glycerophospholipids are major components of cell membranes and consist of a glycerol backbone esterified with one of over 30 unique fatty acids at each of the sn-1 and sn-2 positions. In addition, in some human cells and tissues as much as 20% of the glycerophospholipids contain a fatty alcohol rather than an ester in the sn-1 position, although it can also occur in the sn-2 position. The sn-3 position of the glycerol backbone contains a phosphodiester bond linked to one of more than 10 unique polar head-groups. Hence, humans contain thousands of unique individual molecular species of phospholipids given the heterogeneity of the sn-1 and sn-2 linkage and carbon chains and the sn-3 polar groups. Phospholipase A2 (PLA2) is a superfamily of enzymes that hydrolyze the sn-2 fatty acyl chain resulting in lyso-phospholipids and free fatty acids that then undergo further metabolism. PLA2's play a critical role in lipid-mediated biological responses and membrane phospholipid remodeling. Among the PLA2 enzymes, the Group VIA calcium-independent PLA2 (GVIA iPLA2), also referred to as PNPLA9, is a fascinating enzyme with broad substrate specificity and it is implicated in a wide variety of diseases. Especially notable, the GVIA iPLA2 is implicated in the sequelae of several neurodegenerative diseases termed "phospholipase A2-associated neurodegeneration" (PLAN) diseases. Despite many reports on the physiological role of the GVIA iPLA2, the molecular basis of its enzymatic specificity was unclear. Recently, we employed state-of-the-art lipidomics and molecular dynamics techniques to elucidate the detailed molecular basis of its substrate specificity and regulation. In this review, we summarize the molecular basis of the enzymatic action of GVIA iPLA2 and provide a perspective on future therapeutic strategies for PLAN diseases targeting GVIA iPLA2.
Collapse
Affiliation(s)
- Daiki Hayashi
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe 657-8501, Japan.
| | - Edward A Dennis
- Department of Pharmacology, Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0601, USA
| |
Collapse
|
3
|
Compartmentalized regulation of lipid signaling in oxidative stress and inflammation: Plasmalogens, oxidized lipids and ferroptosis as new paradigms of bioactive lipid research. Prog Lipid Res 2023; 89:101207. [PMID: 36464139 DOI: 10.1016/j.plipres.2022.101207] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/24/2022] [Accepted: 11/27/2022] [Indexed: 12/03/2022]
Abstract
Perturbations in lipid homeostasis combined with conditions favoring oxidative stress constitute a hallmark of the inflammatory response. In this review we focus on the most recent results concerning lipid signaling in various oxidative stress-mediated responses and inflammation. These include phagocytosis and ferroptosis. The best characterized event, common to these responses, is the synthesis of oxygenated metabolites of arachidonic acid and other polyunsaturated fatty acids. Major developments in this area have highlighted the importance of compartmentalization of the enzymes and lipid substrates in shaping the appropriate response. In parallel, other relevant lipid metabolic pathways are also activated and, until recently, there has been a general lack of knowledge on the enzyme regulation and molecular mechanisms operating in these pathways. Specifically, data accumulated in recent years on the regulation and biological significance of plasmalogens and oxidized phospholipids have expanded our knowledge on the involvement of lipid metabolism in the progression of disease and the return to homeostasis. These recent major developments have helped to establish the concept of membrane phospholipids as cellular repositories for the compartmentalized production of bioactive lipids involved in cellular regulation. Importantly, an enzyme classically described as being involved in regulating the homeostatic turnover of phospholipids, namely the group VIA Ca2+-independent phospholipase A2 (iPLA2β), has taken center stage in oxidative stress and inflammation research owing to its key involvement in regulating metabolic and ferroptotic signals arising from membrane phospholipids. Understanding the role of iPLA2β in ferroptosis and metabolism not only broadens our knowledge of disease but also opens possible new horizons for this enzyme as a target for therapeutic intervention.
Collapse
|
4
|
Hu X, Zhang B, Zheng X, Ji H, Feng K, Hu X, Gul I, Abbas MN, Cui H, Zhu Y. Molecular Characterization of Two Genes Encoding Novel Ca2+-Independent Phospholipase A2s from the Silkworm, Bombyx mori. Curr Issues Mol Biol 2022; 44:777-790. [PMID: 35723339 PMCID: PMC8929031 DOI: 10.3390/cimb44020054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/17/2022] [Accepted: 01/21/2022] [Indexed: 11/23/2022] Open
Abstract
Eicosanoids are crucial downstream signals in the insect immune responses. Phospholipase A2 (PLA2) catalyzes phospholipids, the initial step in eicosanoid biosynthesis. In mammals, the biological roles of Ca2+-independent Phospholipase A2 (iPLA2) have been extensively studied; however, only a few studies have attempted to explore iPLA2 functions in insects. In this study, we identified two iPLA2 genes (designated as BmiPLA2A and BmiPLA2B) in the silkworm, Bombyx mori. BmiPLA2A had a 2427 base pair (bp) open reading frame (ORF) that coded for a protein with 808 amino acids. In contrast, BmiPLA2B had a 1731 bp ORF that coded for a protein with 576 amino acids. Domain analysis revealed that BmiPLA2A had six ankyrin repeat domains, but BmiPLA2B lacks these domains. BmiPLA2A and BmiPLA2B were transcribed widely in various tissues and developmental stages with different expression patterns. The administration of 20-hydroxyecdysone increased their expression levels in the epidermis and hemocytes. Furthermore, challenged with virus, fungus, Gram-negative bacteria, and Gram-positive bacteria induced the expression of BmiPLA2A and BmiPLA2B with variable degrees along with different time points. Our findings imply that BmiPLA2A and BmiPLA2B may have important biological roles in the development and innate immunity of B. mori.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Hongjuan Cui
- Correspondence: (H.C.); (Y.Z.); Tel.: +23-6825-1713 (H.C.); +23-6825-1939 (Y.Z.)
| | - Yong Zhu
- Correspondence: (H.C.); (Y.Z.); Tel.: +23-6825-1713 (H.C.); +23-6825-1939 (Y.Z.)
| |
Collapse
|
5
|
Dabral D, van den Bogaart G. The Roles of Phospholipase A 2 in Phagocytes. Front Cell Dev Biol 2021; 9:673502. [PMID: 34179001 PMCID: PMC8222813 DOI: 10.3389/fcell.2021.673502] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
Phagocytic cells, such as macrophages, neutrophils, and dendritic cells, ingest particles larger than about 0.5 μM and thereby clear microbial pathogens and malignant cells from the body. These phagocytic cargoes are proteolytically degraded within the lumen of phagosomes, and peptides derived from them are presented on Major Histocompatibility Complexes (MHC) for the activation of T cells. Mammalian PLA2 isozymes belong to a large family of enzymes that cleave phospholipids at the second position of the glycerol backbone, releasing a free fatty acid and a lysolipid moiety. In human macrophages, at least 15 different PLA2 forms are expressed, and expression of many of these is dependent on pathogenic stimulation. Intriguing questions are why so many PLA2 forms are expressed in macrophages, and what are the functional consequences of their altered gene expression after encountering pathogenic stimuli. In this review, we discuss the evidence of the differential roles of different forms of PLA2 in phagocytic immune cells. These roles include: lipid signaling for immune cell activation, initial phagocytic particle uptake, microbial action for the killing and degradation of ingested microbes, and the repair of membranes induced by oxygen radicals. We also discuss the roles of PLA2 in the subsequent digestion of ingested phagocytic cargoes for antigen presentation to T cells.
Collapse
Affiliation(s)
- Deepti Dabral
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Geert van den Bogaart
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| |
Collapse
|
6
|
Choline Glycerophospholipid-Derived Prostaglandins Attenuate TNFα Gene Expression in Macrophages via a cPLA 2α/COX-1 Pathway. Cells 2021; 10:cells10020447. [PMID: 33669841 PMCID: PMC7923243 DOI: 10.3390/cells10020447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 12/19/2022] Open
Abstract
Macrophages are professional antigen presenting cells with intense phagocytic activity, strategically distributed in tissues and cavities. These cells are capable of responding to a wide variety of innate inflammatory stimuli, many of which are signaled by lipid mediators. The distribution of arachidonic acid (AA) among glycerophospholipids and its subsequent release and conversion into eicosanoids in response to inflammatory stimuli such as zymosan, constitutes one of the most studied models. In this work, we used liquid and/or gas chromatography coupled to mass spectrometry to study the changes in the levels of membrane glycerophospholipids of mouse peritoneal macrophages and the implication of group IVA cytosolic phospholipase A2 (cPLA2α) in the process. In the experimental model used, we observed that the acute response of macrophages to zymosan stimulation involves solely the cyclooxygenase-1 (COX-1), which mediates the rapid synthesis of prostaglandins E2 and I2. Using pharmacological inhibition and antisense inhibition approaches, we established that cPLA2α is the enzyme responsible for AA mobilization. Zymosan stimulation strongly induced the hydrolysis of AA-containing choline glycerophospholipids (PC) and a unique phosphatidylinositol (PI) species, while the ethanolamine-containing glycerophospholipids remained constant or slightly increased. Double-labeling experiments with 3H- and 14C-labeled arachidonate unambiguously demonstrated that PC is the major, if not the exclusive source, of AA for prostaglandin E2 production, while both PC and PI appeared to contribute to prostaglandin I2 synthesis. Importantly, in this work we also show that the COX-1-derived prostaglandins produced during the early steps of macrophage activation restrict tumor necrosis factor-α production. Collectively, these findings suggest new approaches and targets to the selective inhibition of lipid mediator production in response to fungal infection.
Collapse
|
7
|
Ansarey SH. Inflammation and JNK's Role in Niacin-GPR109A Diminished Flushed Effect in Microglial and Neuronal Cells With Relevance to Schizophrenia. Front Psychiatry 2021; 12:771144. [PMID: 34916973 PMCID: PMC8668869 DOI: 10.3389/fpsyt.2021.771144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 11/02/2021] [Indexed: 12/28/2022] Open
Abstract
Schizophrenia is a neuropsychiatric illness with no single definitive aetiology, making its treatment difficult. Antipsychotics are not fully effective because they treat psychosis rather than the cognitive or negative symptoms. Antipsychotics fail to alleviate symptoms when patients enter the chronic stage of illness. Topical application of niacin showed diminished skin flush in the majority of patients with schizophrenia compared to the general population who showed flushing. The niacin skin flush test is useful for identifying patients with schizophrenia at their ultra-high-risk stage, and understanding this pathology may introduce an effective treatment. This review aims to understand the pathology behind the diminished skin flush response, while linking it back to neurons and microglia. First, it suggests that there are altered proteins in the GPR109A-COX-prostaglandin pathway, inflammatory imbalance, and kinase signalling pathway, c-Jun N-terminal kinase (JNK), which are associated with diminished flush. Second, genes from the GPR109A-COX-prostaglandin pathway were matched against the 128-loci genome wide association study (GWAS) for schizophrenia using GeneCards, suggesting that G-coupled receptor-109A (GPR109A) may have a genetic mutation, resulting in diminished flush. This review also suggests that there may be increased pro-inflammatory mediators in the GPR109A-COX-prostaglandin pathway, which contributes to the diminished flush pathology. Increased levels of pro-inflammatory markers may induce microglial-activated neuronal death. Lastly, this review explores the role of JNK on pro-inflammatory mediators, proteins in the GPR109A-COX-prostaglandin pathway, microglial activation, and neuronal death. Inhibiting JNK may reverse the changes observed in the diminished flush response, which might make it a good therapeutic target.
Collapse
Affiliation(s)
- Sabrina H Ansarey
- Department of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| |
Collapse
|
8
|
Astudillo AM, Meana C, Bermúdez MA, Pérez-Encabo A, Balboa MA, Balsinde J. Release of Anti-Inflammatory Palmitoleic Acid and Its Positional Isomers by Mouse Peritoneal Macrophages. Biomedicines 2020; 8:biomedicines8110480. [PMID: 33172033 PMCID: PMC7694668 DOI: 10.3390/biomedicines8110480] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 10/31/2020] [Accepted: 11/02/2020] [Indexed: 12/12/2022] Open
Abstract
Positional isomers of hexadecenoic acid are considered as fatty acids with anti-inflammatory properties. The best known of them, palmitoleic acid (cis-9-hexadecenoic acid, 16:1n-7), has been identified as a lipokine with important beneficial actions in metabolic diseases. Hypogeic acid (cis-7-hexadecenoic acid, 16:1n-9) has been regarded as a possible biomarker of foamy cell formation during atherosclerosis. Notwithstanding the importance of these isomers as possible regulators of inflammatory responses, very little is known about the regulation of their levels and distribution and mobilization among the different lipid pools within the cell. In this work, we describe that the bulk of hexadecenoic fatty acids found in mouse peritoneal macrophages is esterified in a unique phosphatidylcholine species, which contains palmitic acid at the sn-1 position, and hexadecenoic acid at the sn-2 position. This species markedly decreases when the macrophages are activated with inflammatory stimuli, in parallel with net mobilization of free hexadecenoic acid. Using pharmacological inhibitors and specific gene-silencing approaches, we demonstrate that hexadecenoic acids are selectively released by calcium-independent group VIA phospholipase A2 under activation conditions. While most of the released hexadecenoic acid accumulates in free fatty acid form, a significant part is also transferred to other phospholipids to form hexadecenoate-containing inositol phospholipids, which are known to possess growth-factor-like-properties, and are also used to form fatty acid esters of hydroxy fatty acids, compounds with known anti-diabetic and anti-inflammatory properties. Collectively, these data unveil new pathways and mechanisms for the utilization of palmitoleic acid and its isomers during inflammatory conditions, and raise the intriguing possibility that part of the anti-inflammatory activity of these fatty acids may be due to conversion to other lipid mediators.
Collapse
Affiliation(s)
- Alma M. Astudillo
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain; (A.M.A.); (C.M.); (M.A.B.); (M.A.B.)
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Clara Meana
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain; (A.M.A.); (C.M.); (M.A.B.); (M.A.B.)
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Miguel A. Bermúdez
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain; (A.M.A.); (C.M.); (M.A.B.); (M.A.B.)
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Alfonso Pérez-Encabo
- Instituto CINQUIMA, Departamento de Química Orgánica, Universidad de Valladolid, 47011 Valladolid, Spain;
| | - María A. Balboa
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain; (A.M.A.); (C.M.); (M.A.B.); (M.A.B.)
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Jesús Balsinde
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain; (A.M.A.); (C.M.); (M.A.B.); (M.A.B.)
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
- Correspondence: ; Tel.: +34-983-423-062
| |
Collapse
|
9
|
Metabolic Effects of Selective Deletion of Group VIA Phospholipase A 2 from Macrophages or Pancreatic Islet Beta-Cells. Biomolecules 2020; 10:biom10101455. [PMID: 33080873 PMCID: PMC7602969 DOI: 10.3390/biom10101455] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/08/2020] [Accepted: 10/13/2020] [Indexed: 12/11/2022] Open
Abstract
To examine the role of group VIA phospholipase A2 (iPLA2β) in specific cell lineages in insulin secretion and insulin action, we prepared mice with a selective iPLA2β deficiency in cells of myelomonocytic lineage, including macrophages (MØ-iPLA2β-KO), or in insulin-secreting β-cells (β-Cell-iPLA2β-KO), respectively. MØ-iPLA2β-KO mice exhibited normal glucose tolerance when fed standard chow and better glucose tolerance than floxed-iPLA2β control mice after consuming a high-fat diet (HFD). MØ-iPLA2β-KO mice exhibited normal glucose-stimulated insulin secretion (GSIS) in vivo and from isolated islets ex vivo compared to controls. Male MØ-iPLA2β-KO mice exhibited enhanced insulin responsivity vs. controls after a prolonged HFD. In contrast, β-cell-iPLA2β-KO mice exhibited impaired glucose tolerance when fed standard chow, and glucose tolerance deteriorated further when introduced to a HFD. β-Cell-iPLA2β-KO mice exhibited impaired GSIS in vivo and from isolated islets ex vivo vs. controls. β-Cell-iPLA2β-KO mice also exhibited an enhanced insulin responsivity compared to controls. These findings suggest that MØ iPLA2β participates in HFD-induced deterioration in glucose tolerance and that this mainly reflects an effect on insulin responsivity rather than on insulin secretion. In contrast, β-cell iPLA2β plays a role in GSIS and also appears to confer some protection against deterioration in β-cell functions induced by a HFD.
Collapse
|
10
|
How is the acyl chain composition of phosphoinositides created and does it matter? Biochem Soc Trans 2020; 47:1291-1305. [PMID: 31657437 PMCID: PMC6824679 DOI: 10.1042/bst20190205] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/27/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022]
Abstract
The phosphoinositide (PIPn) family of signalling phospholipids are central regulators in membrane cell biology. Their varied functions are based on the phosphorylation pattern of their inositol ring, which can be recognized by selective binding domains in their effector proteins and be modified by a series of specific PIPn kinases and phosphatases, which control their interconversion in a spatial and temporal manner. Yet, a unique feature of PIPns remains largely unexplored: their unusually uniform acyl chain composition. Indeed, while most phospholipids present a range of molecular species comprising acyl chains of diverse length and saturation, PIPns in several organisms and tissues show the predominance of a single hydrophobic backbone, which in mammals is composed of arachidonoyl and stearoyl chains. Despite evolution having favoured this specific PIPn configuration, little is known regarding the mechanisms and functions behind it. In this review, we explore the metabolic pathways that could control the acyl chain composition of PIPns as well as the potential roles of this selective enrichment. While our understanding of this phenomenon has been constrained largely by the technical limitations in the methods traditionally employed in the PIPn field, we believe that the latest developments in PIPn analysis should shed light onto this old question.
Collapse
|
11
|
Functional interaction of bacterial virulence factors of Xenorhabdus nematophila with a calcium-independent cytosolic PLA 2 of Spodoptera exigua. J Invertebr Pathol 2019; 169:107309. [PMID: 31857124 DOI: 10.1016/j.jip.2019.107309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/12/2019] [Accepted: 12/14/2019] [Indexed: 11/23/2022]
Abstract
Phospholipase A2 (PLA2) hydrolyzes the ester bond of phospholipids (PLs) at sn-2 and releases free fatty acids and lysophospholipids that are subsequently changed into various signal molecules to mediate various physiological processes. Numerous PLA2s are known in various biological systems and can be divided into at least 16 groups. Although different PLA2s recently have been annotated from several insect species, physiological roles are known for only a few genes. Two calcium-independent PLA2s (Se-iPLA2A and Se-iPLA2B) are known in the beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae). We generated and purified a recombinant Se-iPLA2B (rSe-iPLA2B) using a bacterial expression system and analyzed the enzyme kinetics. rSe-iPLA2B exhibited catalytic activities against both arachidonyl (AA)-PL and non-AA-PL substrates. It was highly susceptible to iPLA2-specific inhibitor, but insensitive to inhibitors specific to secretory PLA2s or calcium-dependent cytosolic PLA2s. Increasing calcium concentrations prevented enzyme activity, and culture medium of an entomopathogenic bacterium, Xenorhabdus nematophila, or its organic extracts significantly inhibited enzyme activity. Binding assays of rSe-iPLA2B with known secondary metabolites identified from X. nematophila indicated that benzylideneacetone was the most potent inhibitor with a high binding affinity at 0.2 μM against rSe-iPLA2B. Furthermore, rSe-iPLA2B catalyzed the release of fatty acids from PLs extracted from S. exigua fat body, suggesting its physiological role in maintaining PL integrity. All these catalytic activities indicate that Se-iPLA2B has the typical biochemical properties of other iPLA2s. Its high binding affinity to secondary metabolites of X. nematophila suggests that it is a molecular target of X. nematophila, an entomopathogen.
Collapse
|
12
|
Dabral D, Coorssen JR. Combined targeted Omic and Functional Assays Identify Phospholipases A₂ that Regulate Docking/Priming in Calcium-Triggered Exocytosis. Cells 2019; 8:cells8040303. [PMID: 30986994 PMCID: PMC6523306 DOI: 10.3390/cells8040303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 03/24/2019] [Accepted: 03/28/2019] [Indexed: 12/12/2022] Open
Abstract
The fundamental molecular mechanism underlying the membrane merger steps of regulated exocytosis is highly conserved across cell types. Although involvement of Phospholipase A₂ (PLA₂) in regulated exocytosis has long been suggested, its function or that of its metabolites-a lyso-phospholipid and a free fatty acid-remain somewhat speculative. Here, using a combined bioinformatics and top-down discovery proteomics approach, coupled with lipidomic analyses, PLA₂ were found to be associated with release-ready cortical secretory vesicles (CV) that possess the minimal molecular machinery for docking, Ca2+ sensing and membrane fusion. Tightly coupling the molecular analyses with well-established quantitative fusion assays, we show for the first time that inhibition of a CV surface calcium independent intracellular PLA₂ and a luminal secretory PLA₂ significantly reduce docking/priming in the late steps of regulated exocytosis, indicating key regulatory roles in the critical step(s) preceding membrane merger.
Collapse
Affiliation(s)
- Deepti Dabral
- Molecular Physiology and Molecular Medicine Research Group, School of Medicine, Western Sydney University, Campbelltown Campus, NSW 2560, Australia.
| | - Jens R Coorssen
- Department of Health Sciences, Faculty of Applied Health Sciences and Department of Biological Sciences, Faculty of Mathematics & Science, Brock University, St. Catharines, ON L2S 3A1, Canada.
| |
Collapse
|
13
|
Phospholipase A 2 catalysis and lipid mediator lipidomics. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:766-771. [PMID: 30905345 DOI: 10.1016/j.bbalip.2018.08.010] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/10/2018] [Accepted: 08/16/2018] [Indexed: 01/09/2023]
Abstract
Phospholipase A2 (PLA2) enzymes are the upstream regulators of the eicosanoid pathway liberating free arachidonic acid from the sn-2 position of membrane phospholipids. Free intracellular arachidonic acid serves as a substrate for the eicosanoid biosynthetic enzymes including cyclooxygenases, lipoxygenases, and cytochrome P450s that lead to inflammation. The Group IVA cytosolic (cPLA2), Group VIA calcium-independent (iPLA2), and Group V secreted (sPLA2) are three well-characterized human enzymes that have been implicated in eicosanoid formation. In this review, we will introduce and summarize the regulation of catalytic activity and cellular localization, structural characteristics, interfacial activation and kinetics, substrate specificity, inhibitor binding and interactions, and the downstream implications for eicosanoid biosynthesis of these three important PLA2 enzymes.
Collapse
|
14
|
Selectivity of phospholipid hydrolysis by phospholipase A 2 enzymes in activated cells leading to polyunsaturated fatty acid mobilization. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:772-783. [PMID: 30010011 DOI: 10.1016/j.bbalip.2018.07.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/08/2018] [Accepted: 07/10/2018] [Indexed: 12/14/2022]
Abstract
Phospholipase A2s are enzymes that hydrolyze the fatty acid at the sn-2 position of the glycerol backbone of membrane glycerophospholipids. Given the asymmetric distribution of fatty acids within phospholipids, where saturated fatty acids tend to be present at the sn-1 position, and polyunsaturated fatty acids such as those of the omega-3 and omega-6 series overwhelmingly localize in the sn-2 position, the phospholipase A2 reaction is of utmost importance as a regulatory checkpoint for the mobilization of these fatty acids and the subsequent synthesis of proinflammatory omega-6-derived eicosanoids on one hand, and omega-3-derived specialized pro-resolving mediators on the other. The great variety of phospholipase A2s, their differential substrate selectivity under a variety of pathophysiological conditions, as well as the different compartmentalization of each enzyme and accessibility to substrate, render this class of enzymes also key to membrane phospholipid remodeling reactions, and the generation of specific lipid mediators not related with canonical metabolites of omega-6 or omega-3 fatty acids. This review highlights novel findings regarding the selective hydrolysis of phospholipids by phospholipase A2s and the influence this may have on the ability of these enzymes to generate distinct lipid mediators with essential functions in biological processes. This brings a new understanding of the cellular roles of these enzymes depending upon activation conditions.
Collapse
|
15
|
Vasquez AM, Mouchlis VD, Dennis EA. Review of four major distinct types of human phospholipase A 2. Adv Biol Regul 2018; 67:212-218. [PMID: 29248300 PMCID: PMC5807221 DOI: 10.1016/j.jbior.2017.10.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 10/20/2017] [Accepted: 10/20/2017] [Indexed: 12/18/2022]
Abstract
The phospholipase A2 superfamily of enzymes plays a significant role in the development and progression of numerous inflammatory diseases. Through their catalytic action on membrane phospholipids, phospholipases are the upstream regulators of the eicosanoid pathway releasing free fatty acids for cyclooxygenases, lipoxygenases, and cytochrome P450 enzymes which produce various well-known inflammatory mediators including leukotrienes, thromboxanes and prostaglandins. Elucidating the association of phospholipases A2 with the membrane, the extraction and binding of phospholipid substrates, and their interactions with small-molecule inhibitors is crucial for the development of new anti-inflammatory therapeutics. Studying phospholipases has been challenging because they act on the surface of cellular membranes and micelles. Multidisciplinary approaches including hydrogen/deuterium exchange mass spectrometry, molecular dynamics simulations, and other computer-aided drug design techniques have been successfully employed by our laboratory to study interactions of phospholipases with membranes, phospholipid substrates and inhibitors. This review summarizes the application of these techniques to study four human recombinant phospholipases A2.
Collapse
Affiliation(s)
- Alexis M Vasquez
- Department of Chemistry and Biochemistry and Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0601, United States
| | - Varnavas D Mouchlis
- Department of Chemistry and Biochemistry and Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0601, United States.
| | - Edward A Dennis
- Department of Chemistry and Biochemistry and Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0601, United States.
| |
Collapse
|
16
|
Ozes B, Karagoz N, Schüle R, Rebelo A, Sobrido MJ, Harmuth F, Synofzik M, Pascual SIP, Colak M, Ciftci-Kavaklioglu B, Kara B, Ordóñez-Ugalde A, Quintáns B, Gonzalez MA, Soysal A, Zuchner S, Battaloglu E. PLA2G6 mutations associated with a continuous clinical spectrum from neuroaxonal dystrophy to hereditary spastic paraplegia. Clin Genet 2017; 92:534-539. [PMID: 28295203 DOI: 10.1111/cge.13008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 03/07/2017] [Accepted: 03/09/2017] [Indexed: 11/28/2022]
Abstract
PLA2G6-associated neurodegeneration (PLAN) and hereditary spastic paraplegia (HSP) are 2 groups of heterogeneous neurodegenerative diseases. In this study, we report PLA2G6 gene mutations in 3 families from Turkey, Morocco, and Romania. Two affected Turkish siblings presenting HSP adds the disease to PLAN phenotypes. They were homozygous for the PLA2G6 missense c.2239C>T, p.Arg747Trp variant and the ages of onset were 9 and 21. Parkinsonism, dystonia or cognitive decline were not the clinical elements in these patients contrary to the cases that has been previously reported with the same variant, however, iron accumulation was evident in their cranial magnetic resonance imaging. The Moroccan patient was homozygous for a novel missense c.1786C>T, p.Leu596Phe variant and the Romanian patient had 2 novel mutations; c.1898C>T, p.Ala633Val and c.1765_1768del, p.Ser589ThrfsTer76. Both of these patients conformed better to childhood onset PLAN with the age of onset at 4 and 7 years, respectively. Interestingly, all identified mutations were affecting the highly conserved patatin-like phospholipase domain of the PLA2G6 protein.
Collapse
Affiliation(s)
- B Ozes
- Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| | - N Karagoz
- Department of Neurology, Bakirkoy Training and Research Hospital for Psychiatry and Neurological Diseases, Istanbul, Turkey
| | - R Schüle
- Department of Neurodegeneration, Hertie Institute for Clinical Brain Research and Centre of Neurology, Tuebingen, Germany.,University of Tuebingen, German Research Center for Neurodegenerative Diseases (DZNE), Tuebingen, Germany
| | - A Rebelo
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida
| | - M-J Sobrido
- Neurogenetics Group, FPGMX-IDIS, Santiago de Compostela, Spain
| | - F Harmuth
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - M Synofzik
- Department of Neurodegeneration, Hertie Institute for Clinical Brain Research and Centre of Neurology, Tuebingen, Germany.,University of Tuebingen, German Research Center for Neurodegenerative Diseases (DZNE), Tuebingen, Germany
| | - S I P Pascual
- Servicio de Neurologia Pediátrica, Hospital Universitario La Paz, Prof. Asociado Departamento de Pediatria, Universidad Autónoma de Madrid, Madrid, Spain
| | - M Colak
- Department of Neurology, Bakirkoy Training and Research Hospital for Psychiatry and Neurological Diseases, Istanbul, Turkey
| | - B Ciftci-Kavaklioglu
- Department of Neurology, Bakirkoy Training and Research Hospital for Psychiatry and Neurological Diseases, Istanbul, Turkey
| | - B Kara
- Department of Radiology, Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Istanbul, Turkey
| | | | - B Quintáns
- Neurogenetics Group, FPGMX-IDIS, Santiago de Compostela, Spain
| | - M A Gonzalez
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida
| | - A Soysal
- Department of Neurology, Bakirkoy Training and Research Hospital for Psychiatry and Neurological Diseases, Istanbul, Turkey
| | - S Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida
| | - E Battaloglu
- Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| |
Collapse
|
17
|
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: 23] [Impact Index Per Article: 3.3] [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.
Collapse
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.
| |
Collapse
|
18
|
Chew WS, Shalini SM, Torta F, Wenk MR, Stohler C, Yeo JF, Herr DR, Ong WY. Role of prefrontal cortical calcium-independent phospholipase A 2 in antinociceptive effect of the norepinephrine reuptake inhibitor antidepresssant maprotiline. Neuroscience 2016; 340:91-100. [PMID: 27789386 DOI: 10.1016/j.neuroscience.2016.10.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 10/12/2016] [Accepted: 10/14/2016] [Indexed: 12/21/2022]
Abstract
The prefrontal cortex is essential for executive functions such as decision-making and planning. There is also accumulating evidence that it is important for the modulation of pain. In this study, we investigated a possible role of prefrontal cortical calcium-independent phospholipase A2 (iPLA2) in antinociception induced by the norepinephrine reuptake inhibitor (NRI) and tetracyclic (tricyclic) antidepressant, maprotiline. Intraperitoneal injections of maprotiline increased iPLA2 mRNA and protein expression in the prefrontal cortex. This treatment also reduced grooming responses to von-Frey hair stimulation of the face after facial carrageenan injection, indicating decreased sensitivity to pain. The antinociceptive effect of maprotiline was abrogated by iPLA2 antisense oligonucleotide injection to the prefrontal cortex, indicating a role of this enzyme in antinociception. In contrast, injection of iPLA2 antisense oligonucleotide to the somatosensory cortex did not reduce the antinociceptive effect of maprotiline. Lipidomic analysis of the prefrontal cortex showed decrease in phosphatidylcholine species, but increase in lysophosphatidylcholine species, indicating increased PLA2 activity, and release of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) after maprotiline treatment. Differences in sphingomyelin/ceramide were also detected. These changes were not observed in maprotiline-treated mice that received iPLA2 antisense oligonucleotide to the prefrontal cortex. Metabolites of DHA and EPA may help to strengthen a known supraspinal antinociceptive pathway from the prefrontal cortex to the periaqueductal gray. Together, results indicate a role of prefrontal cortical iPLA2 and its enzymatic products in the antinociceptive effect of maprotiline.
Collapse
Affiliation(s)
- Wee-Siong Chew
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260, Singapore
| | - Suku-Maran Shalini
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260, Singapore; Neurobiology and Ageing Research Programme, National University of Singapore, Singapore 119260, Singapore
| | - Federico Torta
- Neurobiology and Ageing Research Programme, National University of Singapore, Singapore 119260, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260, Singapore
| | - Markus R Wenk
- Neurobiology and Ageing Research Programme, National University of Singapore, Singapore 119260, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260, Singapore; Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 119260, Singapore
| | | | - Jin-Fei Yeo
- Division of Oral and Maxillofacial Surgery, Faculty of Dentistry, National University of Singapore, Singapore 119260, Singapore
| | - Deron R Herr
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260, Singapore
| | - Wei-Yi Ong
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260, Singapore; Neurobiology and Ageing Research Programme, National University of Singapore, Singapore 119260, Singapore.
| |
Collapse
|
19
|
Ashley JW, Hancock WD, Nelson AJ, Bone RN, Tse HM, Wohltmann M, Turk J, Ramanadham S. Polarization of Macrophages toward M2 Phenotype Is Favored by Reduction in iPLA2β (Group VIA Phospholipase A2). J Biol Chem 2016; 291:23268-23281. [PMID: 27650501 DOI: 10.1074/jbc.m116.754945] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Indexed: 11/06/2022] Open
Abstract
Macrophages are important in innate and adaptive immunity. Macrophage participation in inflammation or tissue repair is directed by various extracellular signals and mediated by multiple intracellular pathways. Activation of group VIA phospholipase A2 (iPLA2β) causes accumulation of arachidonic acid, lysophospholipids, and eicosanoids that can promote inflammation and pathologic states. We examined the role of iPLA2β in peritoneal macrophage immune function by comparing wild type (WT) and iPLA2β-/- mouse macrophages. Compared with WT, iPLA2β-/- macrophages exhibited reduced proinflammatory M1 markers when classically activated. In contrast, anti-inflammatory M2 markers were elevated under naïve conditions and induced to higher levels by alternative activation in iPLA2β-/- macrophages compared with WT. Induction of eicosanoid (12-lipoxygenase (12-LO) and cyclooxygenase 2 (COX2))- and reactive oxygen species (NADPH oxidase 4 (NOX4))-generating enzymes by classical activation pathways was also blunted in iPLA2β-/- macrophages compared with WT. The effects of inhibitors of iPLA2β, COX2, or 12-LO to reduce M1 polarization were greater than those to enhance M2 polarization. Certain lipids (lysophosphatidylcholine, lysophosphatidic acid, and prostaglandin E2) recapitulated M1 phenotype in iPLA2β-/- macrophages, but none tested promoted M2 phenotype. These findings suggest that (a) lipids generated by iPLA2β and subsequently oxidized by cyclooxygenase and 12-LO favor macrophage inflammatory M1 polarization, and (b) the absence of iPLA2β promotes macrophage M2 polarization. Reducing macrophage iPLA2β activity and thereby attenuating macrophage M1 polarization might cause a shift from an inflammatory to a recovery/repair milieu.
Collapse
Affiliation(s)
- Jason W Ashley
- From the Department of Biology, Eastern Washington University, Cheney, Washington 99004
| | - William D Hancock
- Department of Cell, Developmental, and Integrative Biology.,Comprehensive Diabetes Center, and
| | - Alexander J Nelson
- Department of Cell, Developmental, and Integrative Biology.,Comprehensive Diabetes Center, and
| | - Robert N Bone
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, and
| | - Hubert M Tse
- Comprehensive Diabetes Center, and.,Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Mary Wohltmann
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, .,Comprehensive Diabetes Center, and
| |
Collapse
|
20
|
Hermansson M, Hänninen S, Hokynar K, Somerharju P. The PNPLA-family phospholipases involved in glycerophospholipid homeostasis of HeLa cells. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1058-1065. [DOI: 10.1016/j.bbalip.2016.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/25/2016] [Accepted: 06/10/2016] [Indexed: 12/17/2022]
|
21
|
Dennis EA. Liberating Chiral Lipid Mediators, Inflammatory Enzymes, and LIPID MAPS from Biological Grease. J Biol Chem 2016; 291:24431-24448. [PMID: 27555328 DOI: 10.1074/jbc.x116.723791] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In 1970, it was well accepted that the central role of lipids was in energy storage and metabolism, and it was assumed that amphipathic lipids simply served a passive structural role as the backbone of biological membranes. As a result, the scientific community was focused on nucleic acids, proteins, and carbohydrates as information-containing molecules. It took considerable effort until scientists accepted that lipids also "encode" specific and unique biological information and play a central role in cell signaling. Along with this realization came the recognition that the enzymes that act on lipid substrates residing in or on membranes and micelles must also have important signaling roles, spurring curiosity into their potentially unique modes of action differing from those acting on water-soluble substrates. This led to the creation of the concept of "surface dilution kinetics" for describing the mechanism of enzymes acting on lipid substrates, as well as the demonstration that lipid enzymes such as phospholipase A2 (PLA2) contain allosteric activator sites for specific phospholipids as well as for membranes. As our understanding of phospholipases advanced, so did the understanding that many of the lipids released by these enzymes are chiral information-containing signaling molecules; for example, PLA2 regulates the generation of precursors for the biosynthesis of eicosanoids and other bioactive lipid mediators of inflammation and resolution underlying disease progression. The creation of the LIPID MAPS initiative in 2003 and the ensuing development of the lipidomics field have revealed that lipid metabolites are central to human metabolism. Today lipids are recognized as key mediators of health and disease as we enter a new era of biomarkers and personalized medicine. This article is my personal "reflection" on these scientific advances.
Collapse
Affiliation(s)
- Edward A Dennis
- From the Department of Chemistry and Biochemistry and Department of Pharmacology, School of Medicine, University of California at San Diego, La Jolla, California 92093-0601.
| |
Collapse
|
22
|
Kim Y, Lee S, Seo S, Kim K. Fatty Acid Composition of Different tissues of Spodoptera exigua Larvae and a Role of Cellular Phospholipase A2. ACTA ACUST UNITED AC 2016. [DOI: 10.5656/ksae.2016.04.0.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
23
|
Beck G, Shinzawa K, Hayakawa H, Baba K, Sumi-Akamaru H, Tsujimoto Y, Mochizuki H. Progressive Axonal Degeneration of Nigrostriatal Dopaminergic Neurons in Calcium-Independent Phospholipase A2β Knockout Mice. PLoS One 2016; 11:e0153789. [PMID: 27078024 PMCID: PMC4831782 DOI: 10.1371/journal.pone.0153789] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 04/04/2016] [Indexed: 11/19/2022] Open
Abstract
Calcium-independent phospholipase A2β (iPLA2β, PLA2G6) is essential for the remodeling of membrane glycerophospholipids. Mutations in this gene are responsible for autosomal recessive, young onset, L-dopa-responsive parkinsonism (PARK14), suggesting a neurodegenerative condition in the nigrostriatal dopaminergic system in patients with PLA2G6 mutations. We previously observed slowly progressive motor deficits in iPLA2β-knockout (KO) mice. To clarify whether a deficiency of iPLA2β leads to the degeneration of nigrostriatal dopaminergic neurons, we analyzed the striatum of iPLA2β-KO mice. At all clinical stages, nerve terminals in the striatum were immunopositive for tyrosine hydroxylase (TH) and dopamine transporter (DAT) in wild-type (WT) control mice. In iPLA2β-KO mice, focal loss of nerve terminals positive for TH and DAT was found from 56 weeks (early clinical stage), although iPLA2β-KO mice at 56 weeks showed no significant decrease in the number of dopaminergic neurons in the substantia nigra compared with age-matched WT mice, as reported previously. At 100 weeks (late clinical stage), greater decreases in DAT immunoreactivity were observed in the striatum of iPLA2β-KO mice. Moreover, strongly TH-positive structures, presumed to be deformed axons, were observed in the neuropils of the striatum of iPLA2β-KO mice starting at 15 weeks (preclinical stage) and increased with age. These results suggest that the degeneration of dopaminergic neurons occurs mainly in the distal region of axons in iPLA2β-KO mice.
Collapse
Affiliation(s)
- Goichi Beck
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Koei Shinzawa
- Department of Medical Genetics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Hideki Hayakawa
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Kousuke Baba
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Hisae Sumi-Akamaru
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yoshihide Tsujimoto
- Department of Medical Genetics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- * E-mail:
| |
Collapse
|
24
|
Membrane and inhibitor interactions of intracellular phospholipases A2. Adv Biol Regul 2015; 61:17-24. [PMID: 26774606 DOI: 10.1016/j.jbior.2015.11.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 11/19/2015] [Accepted: 11/20/2015] [Indexed: 02/06/2023]
Abstract
Studying phospholipases A2 (PLA2s) is a challenging task since they act on membrane-like aggregated substrates and not on monomeric phospholipids. Multidisciplinary approaches that include hydrogen/deuterium exchange mass spectrometry (DXMS) and computational techniques have been employed with great success in order to address important questions about the mode of interactions of PLA2 enzymes with membranes, phospholipid substrates and inhibitors. Understanding the interactions of PLA2s is crucial since these enzymes are the upstream regulators of the eicosanoid pathway liberating free arachidonic acid (AA) and other polyunsaturated fatty acids (PUFA). The liberation of AA by PLA2 enzymes sets off a cascade of molecular events that involves downstream regulators such as cyclooxygenase (COX) and lipoxygenase (LOX) metabolites leading to inflammation. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) work by inhibiting COX, while Zileuton inhibits LOX and both rely on PLA2 enzymes to provide them with AA. That means PLA2 enzymes can potentially also be targeted to diminish inflammation at an earlier point in the process. In this review we describe extensive efforts reported in the past to define the interactions of PLA2 enzymes with membranes, substrate phospholipids and inhibitors using DXMS, molecular docking, and molecular dynamics (MD) simulations.
Collapse
|
25
|
Park Y, Kumar S, Kanumuri R, Stanley D, Kim Y. A novel calcium-independent cellular PLA2 acts in insect immunity and larval growth. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 66:13-23. [PMID: 26429672 DOI: 10.1016/j.ibmb.2015.09.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 06/05/2023]
Abstract
Phospholipase A2 (PLA2) catalyzes the position-specific hydrolysis of fatty acids linked to the sn-2 position of phospholipids (PLs). PLA2s make up a very large superfamily, with more than known 15 groups, classified into secretory PLA2 (sPLA2), Ca(2+)-dependent cellular PLA2 (sPLA2) and Ca(2+)-independent cellular PLA2 (iPLA2). Only a few insect sPLA2s, expressed in venom glands and immune tissues, have been characterized at the molecular level. This study aimed to test our hypothesis that insects express iPLA2, using the beet armyworm, Spodoptera exigua, our model insect. Substantial PLA2 activities under calcium-free condition were recorded in several larval tissue preparations. The PLA2 activity was significantly reduced in reactions conducted in the presence of a specific iPLA2 inhibitor, bromoenol lactone (BEL). Analysis of a S. exigua hemocyte transcriptome identified a candidate iPLA2 gene (SeiPLA2-A). The open reading frame encoded 816 amino acid residues with a predicted molecular weight of 90.5 kDa and 6.15 pI value. Our phylogenetic analysis clustered SeiPLA2-A with the other vertebrate iPLA2s. SeiPLA2-A was expressed in all tissues we examined, including hemocytes, fat body, midgut, salivary glands, Malpighian tubules and epidermis. Heterologous expression in Sf9 cells indicated that SeiPLA2-A was localized in cytoplasm and exhibited significant PLA2 activity, which was independent of Ca(2+) and inhibited by BEL. RNA interference (RNAi) of SeiPLA2-A using its specific dsRNA in the fifth instar larvae significantly suppressed iPLA2 expression and enzyme activity. dsSeiPLA2-A-treated larvae exhibited significant loss of cellular immune response, measured as nodule formation in response to bacterial challenge, and extended larval-to-pupal developmental time. These results support our hypothesis, showing that SeiPLA2-A predicted from the transcriptome analysis catalyzes hydrolysis of fatty acids from cellular PLs and plays crucial physiological roles in insect immunity and larval growth.
Collapse
Affiliation(s)
- Youngjin Park
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
| | - Sunil Kumar
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
| | - Rahul Kanumuri
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
| | - David Stanley
- Biological Control of Insects Research Laboratory, USDA/Agricultural Research Service, 1503 Providence Rd., Columbia, MO 65203, USA
| | - Yonggyun Kim
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea.
| |
Collapse
|
26
|
Beck G, Shinzawa K, Hayakawa H, Baba K, Yasuda T, Sumi-Akamaru H, Tsujimoto Y, Mochizuki H. Deficiency of Calcium-Independent Phospholipase A2 Beta Induces Brain Iron Accumulation through Upregulation of Divalent Metal Transporter 1. PLoS One 2015; 10:e0141629. [PMID: 26506412 PMCID: PMC4624760 DOI: 10.1371/journal.pone.0141629] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/09/2015] [Indexed: 01/19/2023] Open
Abstract
Mutations in PLA2G6 have been proposed to be the cause of neurodegeneration with brain iron accumulation type 2. The present study aimed to clarify the mechanism underlying brain iron accumulation during the deficiency of calcium-independent phospholipase A2 beta (iPLA2β), which is encoded by the PLA2G6 gene. Perl's staining with diaminobenzidine enhancement was used to visualize brain iron accumulation. Western blotting was used to investigate the expression of molecules involved in iron homeostasis, including divalent metal transporter 1 (DMT1) and iron regulatory proteins (IRP1 and 2), in the brains of iPLA2β-knockout (KO) mice as well as in PLA2G6-knockdown (KD) SH-SY5Y human neuroblastoma cells. Furthermore, mitochondrial functions such as ATP production were examined. We have discovered for the first time that marked iron deposition was observed in the brains of iPLA2β-KO mice since the early clinical stages. DMT1 and IRP2 were markedly upregulated in all examined brain regions of aged iPLA2β-KO mice compared to age-matched wild-type control mice. Moreover, peroxidized lipids were increased in the brains of iPLA2β-KO mice. DMT1 and IRPs were significantly upregulated in PLA2G6-KD cells compared with cells treated with negative control siRNA. Degeneration of the mitochondrial inner membrane and decrease of ATP production were observed in PLA2G6-KD cells. These results suggest that the genetic ablation of iPLA2β increased iron uptake in the brain through the activation of IRP2 and upregulation of DMT1, which may be associated with mitochondrial dysfunction.
Collapse
Affiliation(s)
- Goichi Beck
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Koei Shinzawa
- Department of Medical Genetics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Hideki Hayakawa
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Kousuke Baba
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Toru Yasuda
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Human Genetics, National Center for Child Health and Development, Tokyo, Japan
| | - Hisae Sumi-Akamaru
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yoshihide Tsujimoto
- Department of Medical Genetics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- * E-mail: (HM)
| |
Collapse
|
27
|
Abstract
Controlled immune responses to infection and injury involve complex molecular signalling networks with coordinated and often opposing actions. Eicosanoids and related bioactive lipid mediators derived from polyunsaturated fatty acids constitute a major bioactive lipid network that is among the most complex and challenging pathways to map in a physiological context. Eicosanoid signalling, similar to cytokine signalling and inflammasome formation, has primarily been viewed as a pro-inflammatory component of the innate immune response; however, recent advances in lipidomics have helped to elucidate unique eicosanoids and related docosanoids with anti-inflammatory and pro-resolution functions. This has advanced our overall understanding of the inflammatory response and its therapeutic implications. The induction of a pro-inflammatory and anti-inflammatory eicosanoid storm through the activation of inflammatory receptors by infectious agents is reviewed here.
Collapse
Affiliation(s)
- Edward A Dennis
- Department of Chemistry and Biochemistry and Department of Pharmacology, School of Medicine, University of California at San Diego, La Jolla, California 92093, USA
| | - Paul C Norris
- Department of Chemistry and Biochemistry and Department of Pharmacology, School of Medicine, University of California at San Diego, La Jolla, California 92093, USA
| |
Collapse
|
28
|
Ramanadham S, Ali T, Ashley JW, Bone RN, Hancock WD, Lei X. Calcium-independent phospholipases A2 and their roles in biological processes and diseases. J Lipid Res 2015; 56:1643-68. [PMID: 26023050 DOI: 10.1194/jlr.r058701] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 12/24/2022] Open
Abstract
Among the family of phospholipases A2 (PLA2s) are the Ca(2+)-independent PLA2s (iPLA2s) and they are designated group VI iPLA2s. In relation to secretory and cytosolic PLA2s, the iPLA2s are more recently described and details of their expression and roles in biological functions are rapidly emerging. The iPLA2s or patatin-like phospholipases (PNPLAs) are intracellular enzymes that do not require Ca(2+) for activity, and contain lipase (GXSXG) and nucleotide-binding (GXGXXG) consensus sequences. Though nine PNPLAs have been recognized, PNPLA8 (membrane-associated iPLA2γ) and PNPLA9 (cytosol-associated iPLA2β) are the most widely studied and understood. The iPLA2s manifest a variety of activities in addition to phospholipase, are ubiquitously expressed, and participate in a multitude of biological processes, including fat catabolism, cell differentiation, maintenance of mitochondrial integrity, phospholipid remodeling, cell proliferation, signal transduction, and cell death. As might be expected, increased or decreased expression of iPLA2s can have profound effects on the metabolic state, CNS function, cardiovascular performance, and cell survival; therefore, dysregulation of iPLA2s can be a critical factor in the development of many diseases. This review is aimed at providing a general framework of the current understanding of the iPLA2s and discussion of the potential mechanisms of action of the iPLA2s and related involved lipid mediators.
Collapse
Affiliation(s)
- Sasanka Ramanadham
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Tomader Ali
- Undergraduate Research Office, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Jason W Ashley
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert N Bone
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - William D Hancock
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Xiaoyong Lei
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| |
Collapse
|
29
|
Guijas C, Rodríguez JP, Rubio JM, Balboa MA, Balsinde J. Phospholipase A2 regulation of lipid droplet formation. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1841:1661-71. [PMID: 25450448 DOI: 10.1016/j.bbalip.2014.10.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/02/2014] [Accepted: 10/14/2014] [Indexed: 02/07/2023]
Abstract
The classical regard of lipid droplets as mere static energy-storage organelles has evolved dramatically. Nowadays these organelles are known to participate in key processes of cell homeostasis, and their abnormal regulation is linked to several disorders including metabolic diseases (diabetes, obesity, atherosclerosis or hepatic steatosis), inflammatory responses in leukocytes, cancer development and neurodegenerative diseases. Hence, the importance of unraveling the cell mechanisms controlling lipid droplet biosynthesis, homeostasis and degradation seems evident Phospholipase A2s, a family of enzymes whose common feature is to hydrolyze the fatty acid present at the sn-2 position of phospholipids, play pivotal roles in cell signaling and inflammation. These enzymes have recently emerged as key regulators of lipid droplet homeostasis, regulating their formation at different levels. This review summarizes recent results on the roles that various phospholipase A2 forms play in the regulation of lipid droplet biogenesis under different conditions. These roles expand the already wide range of functions that these enzymes play in cell physiology and pathophysiology.
Collapse
|
30
|
Group VIB calcium-independent phospholipase A2 (iPLA2γ) regulates platelet activation, hemostasis and thrombosis in mice. PLoS One 2014; 9:e109409. [PMID: 25313821 PMCID: PMC4196902 DOI: 10.1371/journal.pone.0109409] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 08/31/2014] [Indexed: 11/19/2022] Open
Abstract
In platelets, group IVA cytosolic phospholipase A2 (cPLA2α) has been implicated as a key regulator in the hydrolysis of platelet membrane phospholipids, leading to pro-thrombotic thromboxane A2 and anti-thrombotic 12-(S)-hydroxyeicosatetranoic acid production. However, studies using cPLA2α-deficient mice have indicated that other PLA2(s) may also be involved in the hydrolysis of platelet glycerophospholipids. In this study, we found that group VIB Ca2+-independent PLA2 (iPLA2γ)-deficient platelets showed decreases in adenosine diphosphate (ADP)-dependent aggregation and ADP- or collagen-dependent thromboxane A2 production. Electrospray ionization mass spectrometry analysis of platelet phospholipids revealed that fatty acyl compositions of ethanolamine plasmalogen and phosphatidylglycerol were altered in platelets from iPLA2γ-null mice. Furthermore, mice lacking iPLA2γ displayed prolonged bleeding times and were protected against pulmonary thromboembolism. These results suggest that iPLA2γ is an additional, long-sought-after PLA2 that hydrolyzes platelet membranes and facilitates platelet aggregation in response to ADP.
Collapse
|
31
|
Shalini SM, Chew WS, Rajkumar R, Dawe GS, Ong WY. Role of constitutive calcium-independent phospholipase A2 beta in hippocampo-prefrontal cortical long term potentiation and spatial working memory. Neurochem Int 2014; 78:96-104. [PMID: 25180675 DOI: 10.1016/j.neuint.2014.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 08/04/2014] [Accepted: 08/22/2014] [Indexed: 01/29/2023]
Abstract
Calcium independent phospholipase A2 (iPLA2) is an 85 kDa protein that catalyzes the hydrolysis of the sn-2 acyl ester bond of glycerophospholipids to liberate free fatty acids and lysophospholipids. In this study, we determined the role of constitutive iPLA2β in long term potentiation (LTP) of the hippocampo-prefrontal cortical pathway in vivo. We also examined the effect of iPLA2β knockdown using the rewarded alternation in T-maze task, a test of spatial working memory which is dependent on this pathway. Intracortical injection of an inhibitor to iPLA2, bromoenol lactone (BEL) or antisense oligonucleotide to iPLA2β in the prefrontal cortex abolished induction of hippocampo-prefrontal cortical LTP. Moreover, iPLA2 inhibition and antisense knockdown resulted in increased errors in the rewarded alternation in T-maze task, indicating negative effects on spatial working memory. BEL or antisense injection did not produce DNA fragmentation in the cortex as demonstrated by TUNEL assay. Results confirm a role of constitutive iPLA2β in hippocampo-prefrontal cortical synaptic plasticity in vivo, and add to previous observations of a role of iPLA2 in hippocampal LTP in vitro, and long-term memory retrieval. They may be relevant in Alzheimer's disease, and other neurodegenerative conditions that are associated with changes in iPLA2.
Collapse
Affiliation(s)
- Suku-Maran Shalini
- Department of Anatomy, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, Singapore
| | - Wee-Siong Chew
- Department of Anatomy, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, Singapore
| | - Ramamoorthy Rajkumar
- Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, Singapore; Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
| | - Gavin S Dawe
- Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, Singapore; Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
| | - Wei-Yi Ong
- Department of Anatomy, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, Singapore.
| |
Collapse
|
32
|
Song H, Wohltmann M, Tan M, Ladenson JH, Turk J. Group VIA phospholipase A2 mitigates palmitate-induced β-cell mitochondrial injury and apoptosis. J Biol Chem 2014; 289:14194-210. [PMID: 24648512 DOI: 10.1074/jbc.m114.561910] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Palmitate (C16:0) induces apoptosis of insulin-secreting β-cells by processes that involve generation of reactive oxygen species, and chronically elevated blood long chain free fatty acid levels are thought to contribute to β-cell lipotoxicity and the development of diabetes mellitus. Group VIA phospholipase A2 (iPLA2β) affects β-cell sensitivity to apoptosis, and here we examined iPLA2β effects on events that occur in β-cells incubated with C16:0. Such events in INS-1 insulinoma cells were found to include activation of caspase-3, expression of stress response genes (C/EBP homologous protein and activating transcription factor 4), accumulation of ceramide, loss of mitochondrial membrane potential, and apoptosis. All of these responses were blunted in INS-1 cells that overexpress iPLA2β, which has been proposed to facilitate repair of oxidized mitochondrial phospholipids, e.g. cardiolipin (CL), by excising oxidized polyunsaturated fatty acid residues, e.g. linoleate (C18:2), to yield lysophospholipids, e.g. monolysocardiolipin (MLCL), that can be reacylated to regenerate the native phospholipid structures. Here the MLCL content of mouse pancreatic islets was found to rise with increasing iPLA2β expression, and recombinant iPLA2β hydrolyzed CL to MLCL and released oxygenated C18:2 residues from oxidized CL in preference to native C18:2. C16:0 induced accumulation of oxidized CL species and of the oxidized phospholipid (C18:0/hydroxyeicosatetraenoic acid)-glycerophosphoethanolamine, and these effects were blunted in INS-1 cells that overexpress iPLA2β, consistent with iPLA2β-mediated removal of oxidized phospholipids. C16:0 also induced iPLA2β association with INS-1 cell mitochondria, consistent with a role in mitochondrial repair. These findings indicate that iPLA2β confers significant protection of β-cells against C16:0-induced injury.
Collapse
Affiliation(s)
- Haowei Song
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Mary Wohltmann
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Min Tan
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Jack H Ladenson
- Division of Laboratory and Genomic Medicine, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - John Turk
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| |
Collapse
|
33
|
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]
|
34
|
Gil-de-Gómez L, Astudillo AM, Guijas C, Magrioti V, Kokotos G, Balboa MA, Balsinde J. Cytosolic group IVA and calcium-independent group VIA phospholipase A2s act on distinct phospholipid pools in zymosan-stimulated mouse peritoneal macrophages. THE JOURNAL OF IMMUNOLOGY 2013; 192:752-62. [PMID: 24337743 DOI: 10.4049/jimmunol.1302267] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Phospholipase A2s generate lipid mediators that constitute an important component of the integrated response of macrophages to stimuli of the innate immune response. Because these cells contain multiple phospholipase A2 forms, the challenge is to elucidate the roles that each of these forms plays in regulating normal cellular processes and in disease pathogenesis. A major issue is to precisely determine the phospholipid substrates that these enzymes use for generating lipid mediators. There is compelling evidence that group IVA cytosolic phospholipase A2 (cPLA2α) targets arachidonic acid-containing phospholipids but the role of the other cytosolic enzyme present in macrophages, the Ca(2+)-independent group VIA phospholipase A2 (iPLA2β) has not been clearly defined. We applied mass spectrometry-based lipid profiling to study the substrate specificities of these two enzymes during inflammatory activation of macrophages with zymosan. Using selective inhibitors, we find that, contrary to cPLA2α, iPLA2β spares arachidonate-containing phospholipids and hydrolyzes only those that do not contain arachidonate. Analyses of the lysophospholipids generated during activation reveal that one of the major species produced, palmitoyl-glycerophosphocholine, is generated by iPLA2β, with minimal or no involvement of cPLA2α. The other major species produced, stearoyl-glycerophosphocholine, is generated primarily by cPLA2α. Collectively, these findings suggest that cPLA2α and iPLA2β act on different phospholipids during zymosan stimulation of macrophages and that iPLA2β shows a hitherto unrecognized preference for choline phospholipids containing palmitic acid at the sn-1 position that could be exploited for the design of selective inhibitors of this enzyme with therapeutic potential.
Collapse
Affiliation(s)
- Luis Gil-de-Gómez
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain
| | | | | | | | | | | | | |
Collapse
|
35
|
Magrioti V, Nikolaou A, Smyrniotou A, Shah I, Constantinou-Kokotou V, Dennis EA, Kokotos G. New potent and selective polyfluoroalkyl ketone inhibitors of GVIA calcium-independent phospholipase A2. Bioorg Med Chem 2013; 21:5823-9. [PMID: 23916152 DOI: 10.1016/j.bmc.2013.07.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 07/06/2013] [Indexed: 10/26/2022]
Abstract
Group VIA calcium-independent phospholipase A2 (GVIA iPLA2) has recently emerged as an important pharmaceutical target. Selective and potent GVIA iPLA2 inhibitors can be used to study its role in various neurological disorders. In the current work, we explore the significance of the introduction of a substituent in previously reported potent GVIA iPLA2 inhibitors. 1,1,1,2,2-Pentafluoro-7-(4-methoxyphenyl)heptan-3-one (GK187) is the most potent and selective GVIA iPLA2 inhibitor ever reported with a XI(50) value of 0.0001, and with no significant inhibition against GIVA cPLA2 or GV sPLA2. We also compare the inhibition of two difluoromethyl ketones on GVIA iPLA2, GIVA cPLA2, and GV sPLA2.
Collapse
Affiliation(s)
- Victoria Magrioti
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Greece
| | | | | | | | | | | | | |
Collapse
|
36
|
Saab-Aoudé S, Bron AM, Creuzot-Garcher CP, Bretillon L, Acar N. A mouse model of in vivo chemical inhibition of retinal calcium-independent phospholipase A2 (iPLA2). Biochimie 2013; 95:903-11. [DOI: 10.1016/j.biochi.2012.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 12/11/2012] [Indexed: 10/27/2022]
|
37
|
Elimam H, Papillon J, Takano T, Cybulsky AV. Complement-mediated activation of calcium-independent phospholipase A2γ: role of protein kinases and phosphorylation. J Biol Chem 2012; 288:3871-85. [PMID: 23258543 DOI: 10.1074/jbc.m112.396614] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In experimental membranous nephropathy, complement C5b-9-induces glomerular epithelial cell (GEC) injury and proteinuria. The effects of C5b-9 are mediated via signaling pathways, including calcium-independent phospholipase A(2)γ (iPLA(2)γ), and mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38. The iPLA(2)γ pathway is cytoprotective. This study addresses the mechanisms of iPLA(2)γ activation. iPLA(2)γ activity was monitored by quantifying prostaglandin E(2) (PGE(2)) production. In GECs, iPLA(2)γ localized at the endoplasmic reticulum and mitochondria. Complement-mediated production of PGE(2) was amplified in GECs that overexpress iPLA(2)γ, compared with control cells, and was blocked by the iPLA(2)γ inhibitor bromoenol lactone in both iPLA(2)γ-overexpressing and control GECs. In GECs that overexpress iPLA(2)γ, complement-mediated PGE(2) production was reduced by inhibitors of MAP/ERK kinase 1 (MEK1) and p38 but not JNK. In COS-1 cells that overexpress iPLA(2)γ and cyclooxygenase-1, PGE(2) production was induced by co-expression of constitutively active MEK1 or MAPK-interacting kinase 1 (MNK1) as well as by stimulation with epidermal growth factor (EGF) + ionomycin. Complement- and EGF + ionomycin-stimulated iPLA(2)γ activity was attenuated by the S511A/S515A double mutation. Moreover, complement and EGF + ionomycin enhanced phosphorylation of Ser-511. Thus, complement-mediated activation of iPLA(2)γ is mediated via ERK and p38 pathways, and phosphorylation of Ser-511 and/or Ser-515 plays a key role in the catalytic activity and signaling of iPLA(2)γ. Defining the mechanisms by which complement activates iPLA(2)γ provides opportunities for development of novel therapeutic approaches to GEC injury and proteinuria.
Collapse
Affiliation(s)
- Hanan Elimam
- Department of Medicine, McGill University Health Centre, McGill University, Montreal, Quebec H3A 1A1, Canada
| | | | | | | |
Collapse
|
38
|
Role of prefrontal cortical calcium independent phospholipase A₂ in antidepressant-like effect of maprotiline. Int J Neuropsychopharmacol 2012; 15:1087-98. [PMID: 21835087 DOI: 10.1017/s1461145711001234] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
There is increasing interest in the pathophysiology and neurochemistry of the prefrontal cortex (PFC) in depression. Blood flow and metabolism are decreased in the PFC of patients with depression compared to controls. Changes in long-chain polyunsaturated fatty acids (PUFAs) are also associated with depression. This study was conducted to elucidate a possible role of PFC activity of an enzyme involved in the release of docosahexaenoic acid (DHA), i.e. calcium-independent phospholipase A2 (iPLA₂), in the effects of the norepinephrine reuptake inhibitor (NRI) antidepressant, maprotiline, in mice. Treatment of Balb/C mice with maprotiline for 4 wk resulted in reduction in the level of behavioural despair, as determined by decreased immobility and increased climbing during the forced swim test. In contrast, mice treated with maprotiline plus bilateral prefrontal cortical injections of antisense oligonucleotide to iPLA₂, showed significantly increased immobility and decreased climbing, to levels comparable to saline-treated controls, indicating abolishment of the antidepressant-like effect of maprotiline. Lipidomic analyses showed significant decreases in phosphatidylcholine species containing long-chain PUFAs and increases in lysophosphatidylcholine after maprotiline treatment, indicating increased PLA₂ activity and endogenous release of eicosapentaenoic acid (EPA) or DHA after maprotiline treatment. These changes in lipid profiles were absent in mice that received maprotiline and PFC injections of antisense oligonucleotide to iPLA₂. Together, the results indicate that PFC iPLA₂ activity plays an important role in the antidepressant-like effect of maprotiline, possibly through endogenous release of long-chain PUFAs.
Collapse
|
39
|
Glynn P. Neuronal phospholipid deacylation is essential for axonal and synaptic integrity. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:633-41. [PMID: 22903185 DOI: 10.1016/j.bbalip.2012.07.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/20/2012] [Accepted: 07/31/2012] [Indexed: 12/24/2022]
Abstract
Recessively-inherited deficiency in the catalytic activity of calcium-independent phospholipase A2-beta (iPLA2β) and neuropathy target esterase (NTE) causes infantile neuroaxonal dystrophy and hereditary spastic paraplegia, respectively. Thus, these two related phospholipases have non-redundant functions that are essential for structural integrity of synapses and axons. Both enzymes are expressed in essentially all neurons and also have independent roles in glia. iPLA2β liberates sn-2 fatty acid and lysophospholipids from diacyl-phospholipids. Ca(2+)-calmodulin tonically-inhibits iPLA2β, but this can be alleviated by oleoyl-CoA. Together with fatty acyl-CoA-mediated conversion of lysophospholipid to diacyl-phospholipid this may regulate sn-2 fatty acyl composition of phospholipids. In the nervous system, iPLA2β is especially important for the turnover of polyunsaturated fatty acid-associated phospholipid at synapses. More information is required on the interplay between iPLA2β and iPLA2-gamma in deacylation of neuronal mitochondrial phospholipids. NTE reduces levels of phosphatidylcholine (PtdCho) by degrading it to glycerophosphocholine and two free fatty acids. The substrate for NTE may be nascent PtdCho complexed with a phospholipid-binding protein. Protein kinase A-mediated phosphorylation enhances PtdCho synthesis and may allow PtdCho accumulation by coordinate inhibition of NTE activity. NTE operates primarily at the endoplasmic reticulum in neuronal soma but is also present in axons. NTE-mediated PtdCho homeostasis facilitates membrane trafficking and this appears most critical for the integrity of axon terminals in the spinal cord and hippocampus. For maintenance of peripheral nerve axons, iPLA2β activity may be able to compensate for NTE-deficiency but not vice-versa. Whether agonists acting at neuronal receptors modulate the activity of either enzyme remains to be determined. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
Collapse
Affiliation(s)
- Paul Glynn
- Department of Cell Physiology & Pharmacology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK.
| |
Collapse
|
40
|
Mock JN, Taliaferro JP, Lu X, Patel SK, Cummings BS, Long TE. Haloenol pyranones and morpholinones as antineoplastic agents of prostate cancer. Bioorg Med Chem Lett 2012; 22:4854-8. [PMID: 22677312 PMCID: PMC3376906 DOI: 10.1016/j.bmcl.2012.05.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 05/04/2012] [Accepted: 05/08/2012] [Indexed: 10/28/2022]
Abstract
Haloenol pyran-2-ones and morpholin-2-ones were synthesized and evaluated as inhibitors of cell growth in two different prostate human cancer cell lines (PC-3 and LNCaP). Analogs derived from L- and D-phenylglycine were found to be the most effective antagonists of LNCaP and PC-3 cell growth. Additional studies reveal that the inhibitors induced G2/M arrest and the (S)-enantiomer of the phenylglycine-based derivatives was a more potent inhibitor of cytosolic iPLA(2)β.
Collapse
Affiliation(s)
- Jason N. Mock
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602-2352, USA
| | - John P. Taliaferro
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602-2352, USA
| | - Xiao Lu
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602-2352, USA
| | - Sravan Kumar Patel
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602-2352, USA
| | - Brian S. Cummings
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602-2352, USA
| | - Timothy E. Long
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602-2352, USA
| |
Collapse
|
41
|
Maintenance of synaptic stability requires calcium-independent phospholipase A₂ activity. Neural Plast 2012; 2012:569149. [PMID: 22685677 PMCID: PMC3364014 DOI: 10.1155/2012/569149] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 02/03/2012] [Accepted: 02/07/2012] [Indexed: 12/31/2022] Open
Abstract
Phospholipases A₂ (PLA₂s) represent one of the largest groups of lipid-modifying enzymes. Over the years, significant advances have been made in understanding their potential physiological and pathological functions. Depending on their calcium requirement for activation, PLA₂s are classified into calcium dependent and independent. This paper mainly focuses on brain calcium-independent PLA₂ (iPLA₂) and on the mechanisms by which they influence neuronal function and regulate synaptic plasticity. Particular attention will be given to the iPLA₂γ isoform and its role in the regulation of synaptic glutamate receptors. In particular, the paper discusses the possibility that brain iPLA₂γ deficiencies could destabilise normal synaptic operation and might contribute to the aetiology of some brain disorders. In this line, the paper presents new data indicating that iPLA₂γ deficiencies accentuate AMPA receptor destabilization and tau phosphorylation, which suggests that this iPLA₂ isoform should be considered as a potential target for the treatment of Tau-related disorders.
Collapse
|
42
|
Kehler AK, Andersen C, Andreasen JR, Vohra R, Junker N, Poulsen KA, Kolko M. Interaction between VEGF and Calcium-Independent Phospholipase A2in Proliferation and Migration of Retinal Pigment Epithelium. Curr Eye Res 2012; 37:500-7. [DOI: 10.3109/02713683.2012.663855] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
43
|
Petrova S, Atanasov V, Balashev K. Vipoxin and Its Components. STRUCTURAL AND MECHANISTIC ENZYMOLOGY - BRINGING TOGETHER EXPERIMENTS AND COMPUTING 2012; 87:117-53. [DOI: 10.1016/b978-0-12-398312-1.00005-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
44
|
Dynamics of arachidonic acid mobilization by inflammatory cells. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:249-56. [PMID: 22155285 DOI: 10.1016/j.bbalip.2011.11.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Revised: 11/19/2011] [Accepted: 11/21/2011] [Indexed: 01/06/2023]
Abstract
The development of mass spectrometry-based techniques is opening new insights into the understanding of arachidonic acid (AA) metabolism. AA incorporation, remodeling and release are collectively controlled by acyltransferases, phospholipases and transacylases that exquisitely regulate the distribution of AA between the different glycerophospholipid species and its mobilization during cellular stimulation. Traditionally, studies involving phospholipid AA metabolism were conducted by using radioactive precursors and scintillation counting from thin layer chromatography separations that provided only information about lipid classes. Today, the input of lipidomic approaches offers the possibility of characterizing and quantifying specific molecular species with great accuracy and within a biological context associated to protein and/or gene expression in a temporal frame. This review summarizes recent results applying mass spectrometry-based lipidomic approaches to the identification of AA-containing glycerophospholipids, phospholipid AA remodeling and synthesis of oxygenated metabolites.
Collapse
|
45
|
Neuroaxonal dystrophy in calcium-independent phospholipase A2β deficiency results from insufficient remodeling and degeneration of mitochondrial and presynaptic membranes. J Neurosci 2011; 31:11411-20. [PMID: 21813701 DOI: 10.1523/jneurosci.0345-11.2011] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Infantile neuroaxonal dystrophy (INAD) is a fatal neurodegenerative disease characterized by the widespread presence of axonal swellings (spheroids) in the CNS and PNS and is caused by gene abnormality in PLA2G6 [calcium-independent phospholipase A(2)β (iPLA(2)β)], which is essential for remodeling of membrane phospholipids. To clarify the pathomechanism of INAD, we pathologically analyzed the spinal cords and sciatic nerves of iPLA(2)β knock-out (KO) mice, a model of INAD. At 15 weeks (preclinical stage), periodic acid-Schiff (PAS)-positive granules were frequently observed in proximal axons and the perinuclear space of large neurons, and these were strongly positive for a marker of the mitochondrial outer membrane and negative for a marker of the inner membrane. By 100 weeks (late clinical stage), PAS-positive granules and spheroids had increased significantly in the distal parts of axons, and ultrastructural examination revealed that these granules were, in fact, mitochondria with degenerative inner membranes. Collapse of mitochondria in axons was accompanied by focal disappearance of the cytoskeleton. Partial membrane loss at axon terminals was also evident, accompanied by degenerative membranes in the same areas. Imaging mass spectrometry showed a prominent increase of docosahexaenoic acid-containing phosphatidylcholine in the gray matter, suggesting insufficient membrane remodeling in the presence of iPLA(2)β deficiency. Prominent axonal degeneration in neuroaxonal dystrophy might be explained by the collapse of abnormal mitochondria after axonal transportation. Insufficient remodeling and degeneration of mitochondrial inner membranes and presynaptic membranes appear to be the cause of the neuroaxonal dystrophy in iPLA(2)β-KO mice.
Collapse
|
46
|
Ueno N, Taketomi Y, Yamamoto K, Hirabayashi T, Kamei D, Kita Y, Shimizu T, Shinzawa K, Tsujimoto Y, Ikeda K, Taguchi R, Murakami M. Analysis of two major intracellular phospholipases A(2) (PLA(2)) in mast cells reveals crucial contribution of cytosolic PLA(2)α, not Ca(2+)-independent PLA(2)β, to lipid mobilization in proximal mast cells and distal fibroblasts. J Biol Chem 2011; 286:37249-63. [PMID: 21880721 DOI: 10.1074/jbc.m111.290312] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mast cells release a variety of mediators, including arachidonic acid (AA) metabolites, to regulate allergy, inflammation, and host defense, and their differentiation and maturation within extravascular microenvironments depend on the stromal cytokine stem cell factor. Mouse mast cells express two major intracellular phospholipases A(2) (PLA(2)s), namely group IVA cytosolic PLA(2) (cPLA(2)α) and group VIA Ca(2+)-independent PLA(2) (iPLA(2)β), and the role of cPLA(2)α in eicosanoid synthesis by mast cells has been well documented. Lipidomic analyses of mouse bone marrow-derived mast cells (BMMCs) lacking cPLA(2)α (Pla2g4a(-/-)) or iPLA(2)β (Pla2g6(-/-)) revealed that phospholipids with AA were selectively hydrolyzed by cPLA(2)α, not by iPLA(2)β, during FcεRI-mediated activation and even during fibroblast-dependent maturation. Neither FcεRI-dependent effector functions nor maturation-driven phospholipid remodeling was impaired in Pla2g6(-/-) BMMCs. Although BMMCs did not produce prostaglandin E(2) (PGE(2)), the AA released by cPLA(2)α from BMMCs during maturation was converted to PGE(2) by microsomal PGE synthase-1 (mPGES-1) in cocultured fibroblasts, and accordingly, Pla2g4a(-/-) BMMCs promoted microenvironmental PGE(2) synthesis less efficiently than wild-type BMMCs both in vitro and in vivo. Mice deficient in mPGES-1 (Ptges(-/-)) had an augmented local anaphylactic response. These results suggest that cPLA(2)α in mast cells is functionally coupled, through the AA transfer mechanism, with stromal mPGES-1 to provide anti-anaphylactic PGE(2). Although iPLA(2)β is partially responsible for PGE(2) production by macrophages and dendritic cells, it is dispensable for mast cell maturation and function.
Collapse
Affiliation(s)
- Noriko Ueno
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 256-8506, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Hermansson M, Hokynar K, Somerharju P. Mechanisms of glycerophospholipid homeostasis in mammalian cells. Prog Lipid Res 2011; 50:240-57. [DOI: 10.1016/j.plipres.2011.02.004] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 02/21/2011] [Accepted: 02/25/2011] [Indexed: 01/09/2023]
|
48
|
Abstract
Phospholipase A(1) (PLA(1)) is an enzyme that hydrolyzes phospholipids and produces 2-acyl-lysophospholipids and fatty acids. This lipolytic activity is conserved in a wide range of organisms but is carried out by a diverse set of PLA(1) enzymes. Where their function is known, PLA(1)s have been shown to act as digestive enzymes, possess central roles in membrane maintenance and remodeling, or regulate important cellular mechanisms by the production of various lysophospholipid mediators, such as lysophosphatidylserine and lysophosphatidic acid, which in turn have multiple biological functions.
Collapse
Affiliation(s)
- Gregory S. Richmond
- Agilent Technologies, Molecular Separations, Santa Clara, CA 95051, USA; E-Mail:
| | - Terry K. Smith
- Centre for Biomolecular Sciences, The North Haugh, The University, St. Andrews, KY16 9ST, Scotland, UK
- To whom correspondence should be addressed; E-Mail: ; Tel.: +44-1334-463412; Fax: +44-1334-462595
| |
Collapse
|
49
|
Murakami M, Taketomi Y, Miki Y, Sato H, Hirabayashi T, Yamamoto K. Recent progress in phospholipase A₂ research: from cells to animals to humans. Prog Lipid Res 2010; 50:152-92. [PMID: 21185866 DOI: 10.1016/j.plipres.2010.12.001] [Citation(s) in RCA: 368] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian genomes encode genes for more than 30 phospholipase A₂s (PLA₂s) or related enzymes, which are subdivided into several classes including low-molecular-weight secreted PLA₂s (sPLA₂s), Ca²+-dependent cytosolic PLA₂s (cPLA₂s), Ca²+-independent PLA₂s (iPLA₂s), platelet-activating factor acetylhydrolases (PAF-AHs), lysosomal PLA₂s, and a recently identified adipose-specific PLA. Of these, the intracellular cPLA₂ and iPLA₂ families and the extracellular sPLA₂ family are recognized as the "big three". From a general viewpoint, cPLA₂α (the prototypic cPLA₂ plays a major role in the initiation of arachidonic acid metabolism, the iPLA₂ family contributes to membrane homeostasis and energy metabolism, and the sPLA₂ family affects various biological events by modulating the extracellular phospholipid milieus. The cPLA₂ family evolved along with eicosanoid receptors when vertebrates first appeared, whereas the diverse branching of the iPLA₂ and sPLA₂ families during earlier eukaryote development suggests that they play fundamental roles in life-related processes. During the past decade, data concerning the unexplored roles of various PLA₂ enzymes in pathophysiology have emerged on the basis of studies using knockout and transgenic mice, the use of specific inhibitors, and information obtained from analysis of human diseases caused by mutations in PLA₂ genes. This review focuses on current understanding of the emerging biological functions of PLA₂s and related enzymes.
Collapse
Affiliation(s)
- Makoto Murakami
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
| | | | | | | | | | | |
Collapse
|
50
|
Song H, Rohrs H, Tan M, Wohltmann M, Ladenson JH, Turk J. Effects of endoplasmic reticulum stress on group VIA phospholipase A2 in beta cells include tyrosine phosphorylation and increased association with calnexin. J Biol Chem 2010; 285:33843-57. [PMID: 20732873 DOI: 10.1074/jbc.m110.153197] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Group VIA phospholipase A(2) (iPLA(2)β) hydrolyzes glycerophospholipids at the sn-2-position to yield a free fatty acid and a 2-lysophospholipid, and iPLA(2)β has been reported to participate in apoptosis, phospholipid remodeling, insulin secretion, transcriptional regulation, and other processes. Induction of endoplasmic reticulum (ER) stress in β-cells and vascular myocytes with SERCA inhibitors activates iPLA(2)β, resulting in hydrolysis of arachidonic acid from membrane phospholipids, by a mechanism that is not well understood. Regulatory proteins interact with iPLA(2)β, including the Ca(2+)/calmodulin-dependent protein kinase IIβ, and we have characterized the iPLA(2)β interactome further using affinity capture and LC/electrospray ionization/MS/MS. An iPLA(2)β-FLAG fusion protein was expressed in an INS-1 insulinoma cell line and then adsorbed to an anti-FLAG matrix after cell lysis. iPLA(2)β and any associated proteins were then displaced with FLAG peptide and analyzed by SDS-PAGE. Gel sections were digested with trypsin, and the resultant peptide mixtures were analyzed by LC/MS/MS with database searching. This identified 37 proteins that associate with iPLA(2)β, and nearly half of them reside in ER or mitochondria. They include the ER chaperone calnexin, whose association with iPLA(2)β increases upon induction of ER stress. Phosphorylation of iPLA(2)β at Tyr(616) also occurs upon induction of ER stress, and the phosphoprotein associates with calnexin. The activity of iPLA(2)β in vitro increases upon co-incubation with calnexin, and overexpression of calnexin in INS-1 cells results in augmentation of ER stress-induced, iPLA(2)β-catalyzed hydrolysis of arachidonic acid from membrane phospholipids, reflecting the functional significance of the interaction. Similar results were obtained with mouse pancreatic islets.
Collapse
Affiliation(s)
- Haowei Song
- Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | | | | | | | | | | |
Collapse
|