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Prakash S, Srilekha D, Srinivas PSN, Sankaranarayanan L, Sowmini PR, Velayudham S, Jeyaraj M, Kannan V, Saravanan RV, Krishnan M. PLA2G6-associated Neurodegeneration: A Rare Case Report of Dystonia-Parkinsonism Phenotype with a Novel Genotypic Variant. THE JOURNAL OF THE ASSOCIATION OF PHYSICIANS OF INDIA 2025; 73:91-93. [PMID: 39928007 DOI: 10.59556/japi.73.0836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2025]
Abstract
PLA2G6-associated neurodegeneration (PLAN) is a complex heterogenous group of neurodegenerative diseases that results from mutations in a gene known as PLA2G6. PLAN comprises three phenotypes with overlapping clinical and radiologic features: (1) Infantile neuroaxonal dystrophy (INAD), (2) Atypical neuroaxonal dystrophy (ANAD), and (3) PLA2G6-related dystonia-parkinsonism complex (PLAN-DPC). The onset of PLA2G6-related DPC occurs in adulthood, and patients often have normal birth and development. These patients show clinical manifestations of Parkinsonian syndrome, characterized by bradykinesia and tremors with dystonia, in addition to cognitive regression as well as gait instability. Here, we report a case of PLAN-DPC phenotype in a 20-year-old girl. This case report highlights the detection of a novel variant of PLA2G6 gene mutation, c.757G>A, which has an allelic frequency of 0.001% in the gene database.
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Affiliation(s)
- Surya Prakash
- Neurology Resident, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India, Corresponding Author
| | - D Srilekha
- Neurology Resident, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
| | - P S Naga Srinivas
- Senior Resident, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
| | | | - P R Sowmini
- Assistant Professor, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
| | - Sakthi Velayudham
- Assistant Professor, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
| | - Malcolm Jeyaraj
- Assistant Professor, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
| | - V Kannan
- Assistant Professor, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
| | - R Viveka Saravanan
- Professor, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
| | - Mugundhan Krishnan
- Professor of Neurology and Head, Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India
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Cheema AN, Shi R, Kamboh MI. Association of Novel Pathogenic Variant (p. Ile366Asn) in PLA2G6 Gene with Infantile Neuroaxonal Dystrophy. Int J Mol Sci 2025; 26:352. [PMID: 39796207 PMCID: PMC11721680 DOI: 10.3390/ijms26010352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2024] [Revised: 12/29/2024] [Accepted: 01/02/2025] [Indexed: 01/13/2025] Open
Abstract
A couple presented to the office with an apparently healthy infant for a thorough clinical assessment, as they had previously lost two male children to a neurodegenerative disorder. They also reported the death of a male cousin abroad with a comparable condition. We aimed to evaluate a novel coding pathogenic variant c.1097T>A, PLA2G6, within the affected family, previously identified in a deceased cousin, but its clinical significance remained undetermined. A 200 bp PCR product of target genome (including codon 366 of PLA2G6) was amplified followed by enzymatic digestion (MboI) and sequencing. Structural pathogenic variant analysis was performed using PyMOL 2.5.4. In RFLP analysis, the mutant-type allele produced a single band of 200 bp, and the wild-type allele manifested as two bands of 112 bp and 88 bp. The pathogenic variant was identified in nine family members, including two heterozygous couples with consanguineous marriages resulting in affected children. It was predicted to be deleterious by multiple bioinformatic tools. The substitution of nonpolar isoleucine with polar asparagine of iPLA2 (Ile366Asn) resulted in a eense pathogenic variant (ATC>AAC). A missense variant (p. Ile366Asn) in the PLA2G6 gene is associated with clinically evident infantile neuroaxonal dystrophy, which is transmitted in an autosomal recessive pattern, and is also predicted to be dysfunctional by bioinformatic analyses.
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Affiliation(s)
- Asma Naseer Cheema
- Children’s Hospital & The Institute of Child Health Multan, Multan 66000, Pakistan
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA; (R.S.); (M.I.K.)
| | - Ruyu Shi
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA; (R.S.); (M.I.K.)
| | - M. Ilyas Kamboh
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA; (R.S.); (M.I.K.)
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Mouchlis VD, Hsu YH, Hayashi D, Cao J, Li S, McCammon JA, Dennis EA. The mechanism of allosteric regulation of calcium-independent phospholipase A 2 by ATP and calmodulin binding to the ankyrin domain. Proc Natl Acad Sci U S A 2024; 121:e2411539121. [PMID: 39560651 PMCID: PMC11621833 DOI: 10.1073/pnas.2411539121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Accepted: 10/07/2024] [Indexed: 11/20/2024] Open
Abstract
Group VIA calcium-independent phospholipase A2 (iPLA2) is a member of the PLA2 superfamily that exhibits calcium-independent activity in contrast to the other two major types, secreted phospholipase A2 (sPLA2) and cytosolic phospholipase A2 (cPLA2), which both require calcium for their enzymatic activity. Adenosine triphosphate (ATP) has been reported to allosterically activate iPLA2, and this has now been verified with a lipidomics-based mixed-micelle assay, but its mechanism of action has been unknown. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) was employed to identify ATP interaction peptide regions located within the ankyrin repeat domain at which ATP interacts. Molecular dynamics simulations revealed the mechanism by which ATP binds to its site and the main residues that interact. Site-directed mutagenesis was used to verify the importance of these residues in the role of ATP in regulating iPLA2 activity. Importantly, calcium was found to abolish the enhancing regulatory function of ATP and to promote the inhibitory activity by calmodulin. Given previous evidence that calcium does not bind directly to iPLA2, its effect appears to be indirect via association with ATP and/or calmodulin. Using HDX-MS, we found that calmodulin interacts with the N terminus peptide region of iPLA2 consisting of residues 20 to 28. These two regulatory iPLA2 sites open the road to the development of potential targets for therapeutic intervention.
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Affiliation(s)
- Varnavas D. Mouchlis
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA92093-0601
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA92093-0601
| | - Yuan-Hao Hsu
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA92093-0601
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA92093-0601
| | - Daiki Hayashi
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA92093-0601
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA92093-0601
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Kobe657-8501, Japan
| | - Jian Cao
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA92093-0601
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA92093-0601
| | - Sheng Li
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA92093
| | - J. Andrew McCammon
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA92093-0601
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA92093-0601
| | - Edward A. Dennis
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA92093-0601
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA92093-0601
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Hayashi D, Dennis EA. Differentiating human phospholipase A 2's activity toward phosphatidylinositol, phosphatidylinositol phosphate and phosphatidylinositol bisphosphate. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159527. [PMID: 38917952 PMCID: PMC11521320 DOI: 10.1016/j.bbalip.2024.159527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/02/2024] [Accepted: 05/24/2024] [Indexed: 06/27/2024]
Abstract
Phospholipase A2's (PLA2's) constitute a superfamily of enzymes that hydrolyze the sn-2 fatty acyl chain on glycerophospholipids. We have previously reported that each PLA2 Type shows a unique substrate specificity for the molecular species it hydrolyzes, especially the acyl chain that is cleaved from the sn-2 position and to some extent the polar group. However, phosphatidylinositol (PI) and PI phosphates (PIPs) have not been as well studied as substrates as other phospholipids because the PIPs require adaptation of the standard analysis methods, but they are important in vivo. We determined the in vitro activity of the three major types of human PLA2's, namely the cytosolic (c), calcium-independent (i), and secreted (s) PLA2's toward PI, PI-4-phosphate (PI(4)P), and PI-4,5-bisphosphate (PI(4,5)P2). The in vitro assay revealed that Group IVA cPLA2 (GIVA cPLA2) showed relatively high activity toward PI and PI(4)P among the tested PLA2's; nevertheless, the highly hydrophilic headgroup disrupted the interaction between the lipid surface and the enzyme. GIVA cPLA2 and GVIA iPLA2 showed detectable activity toward PI(4,5)P2, but it appeared to be a poorer substrate for all of the PLA2's tested. Furthermore, molecular dynamics (MD) simulations demonstrated that Thr416 and Glu418 of GIVA cPLA2 contribute significantly to accommodating the hydrophilic head groups of PI and PI(4)P, which could explain some selectivity for PI and PI(4)P. These results indicated that GIVA cPLA2 can accommodate PI and PI(4)P in its active site and hydrolyze them, suggesting that the GIVA cPLA2 may best account for the PI and PIP hydrolysis in living cells.
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Affiliation(s)
- Daiki Hayashi
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Faculty of Agriculture, Kobe University, Kobe 657-8501, Japan; Department of Pharmacology and Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Edward A Dennis
- Department of Pharmacology and Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
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Liu J, Tan J, Tang B, Guo J. Unveiling the role of iPLA 2β in neurodegeneration: From molecular mechanisms to advanced therapies. Pharmacol Res 2024; 202:107114. [PMID: 38395207 DOI: 10.1016/j.phrs.2024.107114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 02/08/2024] [Accepted: 02/20/2024] [Indexed: 02/25/2024]
Abstract
Calcium-independent phospholipase A2β (iPLA2β), a member of the phospholipase A2 (PLA2s) superfamily, is encoded by the PLA2G6 gene. Mutations in the PLA2G6 gene have been identified as the primary cause of infantile neuroaxonal dystrophy (INAD) and, less commonly, as a contributor to Parkinson's disease (PD). Recent studies have revealed that iPLA2β deficiency leads to neuroinflammation, iron accumulation, mitochondrial dysfunction, lipid dysregulation, and other pathological changes, forming a complex pathogenic network. These discoveries shed light on potential mechanisms underlying PLA2G6-associated neurodegeneration (PLAN) and offer valuable insights for therapeutic development. This review provides a comprehensive analysis of the fundamental characteristics of iPLA2β, its association with neurodegeneration, the pathogenic mechanisms involved in PLAN, and potential targets for therapeutic intervention. It offers an overview of the latest advancements in this field, aiming to contribute to ongoing research endeavors and facilitate the development of effective therapies for PLAN.
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Affiliation(s)
- Jiabin Liu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jieqiong Tan
- Centre for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China; Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jifeng Guo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China; Centre for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China; National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China.
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Ramanadham S, Turk J, Bhatnagar S. Noncanonical Regulation of cAMP-Dependent Insulin Secretion and Its Implications in Type 2 Diabetes. Compr Physiol 2023; 13:5023-5049. [PMID: 37358504 PMCID: PMC10809800 DOI: 10.1002/cphy.c220031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Impaired glucose tolerance (IGT) and β-cell dysfunction in insulin resistance associated with obesity lead to type 2 diabetes (T2D). Glucose-stimulated insulin secretion (GSIS) from β-cells occurs via a canonical pathway that involves glucose metabolism, ATP generation, inactivation of K ATP channels, plasma membrane depolarization, and increases in cytosolic concentrations of [Ca 2+ ] c . However, optimal insulin secretion requires amplification of GSIS by increases in cyclic adenosine monophosphate (cAMP) signaling. The cAMP effectors protein kinase A (PKA) and exchange factor activated by cyclic-AMP (Epac) regulate membrane depolarization, gene expression, and trafficking and fusion of insulin granules to the plasma membrane for amplifying GSIS. The widely recognized lipid signaling generated within β-cells by the β-isoform of Ca 2+ -independent phospholipase A 2 enzyme (iPLA 2 β) participates in cAMP-stimulated insulin secretion (cSIS). Recent work has identified the role of a G-protein coupled receptor (GPCR) activated signaling by the complement 1q like-3 (C1ql3) secreted protein in inhibiting cSIS. In the IGT state, cSIS is attenuated, and the β-cell function is reduced. Interestingly, while β-cell-specific deletion of iPLA 2 β reduces cAMP-mediated amplification of GSIS, the loss of iPLA 2 β in macrophages (MØ) confers protection against the development of glucose intolerance associated with diet-induced obesity (DIO). In this article, we discuss canonical (glucose and cAMP) and novel noncanonical (iPLA 2 β and C1ql3) pathways and how they may affect β-cell (dys)function in the context of impaired glucose intolerance associated with obesity and T2D. In conclusion, we provide a perspective that in IGT states, targeting noncanonical pathways along with canonical pathways could be a more comprehensive approach for restoring β-cell function in T2D. © 2023 American Physiological Society. Compr Physiol 13:5023-5049, 2023.
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Affiliation(s)
- Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Alabama, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sushant Bhatnagar
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
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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: 8] [Impact Index Per Article: 4.0] [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.
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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
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Altuame FD, Foskett G, Atwal PS, Endemann S, Midei M, Milner P, Salih MA, Hamad M, Al-Muhaizea M, Hashem M, Alkuraya FS. The natural history of infantile neuroaxonal dystrophy. Orphanet J Rare Dis 2020; 15:109. [PMID: 32357911 PMCID: PMC7193406 DOI: 10.1186/s13023-020-01355-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 03/17/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Infantile neuroaxonal dystrophy (INAD) is a rapidly progressive neurodegenerative disorder of early onset causing premature death. It results from biallelic pathogenic variants in PLA2G6, which encodes a calcium-independent phospholipase A2. OBJECTIVE We aim to outline the natural history of INAD and provide a comprehensive description of its clinical, radiological, laboratory, and molecular findings. MATERIALS AND METHODS We comprehensively analyzed the charts of 28 patients: 16 patients from Riyadh, Saudi Arabia, 8 patients from North and South America and 4 patients from Europe with a molecularly confirmed diagnosis of PLA2G6-associated neurodegeneration (PLAN) and a clinical history consistent with INAD. RESULTS In our cohort, speech impairment and loss of gross motor milestones were the earliest signs of the disease. As the disease progressed, loss of fine motor milestones and bulbar dysfunction were observed. Temporo-frontal function was among the last of the milestones to be lost. Appendicular spastic hypertonia, axial hypotonia, and hyperreflexia were common neurological findings. Other common clinical findings include nystagmus (60.7%), seizures (42.9%), gastrointestinal disease (42.9%), skeletal deformities (35.7%), and strabismus (28.6%). Cerebellar atrophy and elevations in serum AST and LDH levels were consistent features of INAD. There was a statistically significant difference when comparing patients with non-sense/truncating variants compared with missense/in-frame deletions in the time of initial concern (p = 0.04), initial loss of language (p = 0.001), initial loss of fine motor skills (p = 0.009), and initial loss of bulbar skills (p = 0.007). CONCLUSION INAD is an ultra-rare neurodegenerative disorder that presents in early childhood, with a relentlessly progressive clinical course. Knowledge of the natural history of INAD may serve as a resource for healthcare providers to develop a targeted care plan and may facilitate the design of clinical trials to treat this disease.
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Affiliation(s)
- Fadie D Altuame
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | | | | | | | | | | | - Mustafa A Salih
- Division of Pediatric Neurology, Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Muddathir Hamad
- Division of Pediatric Neurology, Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Mohammad Al-Muhaizea
- Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Mais Hashem
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
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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.
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Guo YP, Tang BS, Guo JF. PLA2G6-Associated Neurodegeneration (PLAN): Review of Clinical Phenotypes and Genotypes. Front Neurol 2018; 9:1100. [PMID: 30619057 PMCID: PMC6305538 DOI: 10.3389/fneur.2018.01100] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 12/03/2018] [Indexed: 12/18/2022] Open
Abstract
Phospholipase A2 group VI (PLA2G6)-associated neurodegeneration (PLAN) includes a series of neurodegenerative diseases that result from the mutations in PLA2G6. PLAN has genetic and clinical heterogeneity, with different mutation sites, mutation types and ethnicities and its clinical phenotype is different. The clinical phenotypes and genotypes of PLAN are closely intertwined and vary widely. PLA2G6 encodes a group of VIA calcium-independent phospholipase A2 proteins (iPLA2β), an enzyme involved in lipid metabolism. According to the age of onset and progressive clinical features, PLAN can be classified into the following subtypes: infantile neuroaxonal dystrophy (INAD), atypical neuroaxonal dystrophy (ANAD) and parkinsonian syndrome which contains adult onset dystonia parkinsonism (DP) and autosomal recessive early-onset parkinsonism (AREP). In this review, we present an overview of PLA2G6-associated neurodegeneration in the context of current research.
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Affiliation(s)
- Yu-Pei Guo
- Center for Brain Disorders Research, Capital Medical University and Beijing Institute of Brain Disorders, Beijing, China.,Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Bei-Sha Tang
- Center for Brain Disorders Research, Capital Medical University and Beijing Institute of Brain Disorders, Beijing, China.,Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Center for Medical Genetics, Central South University, Changsha, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
| | - Ji-Feng Guo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Center for Medical Genetics, Central South University, Changsha, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
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11
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Turk J, White TD, Nelson AJ, Lei X, Ramanadham S. iPLA 2β and its role in male fertility, neurological disorders, metabolic disorders, and inflammation. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:846-860. [PMID: 30408523 DOI: 10.1016/j.bbalip.2018.10.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 10/26/2018] [Accepted: 10/29/2018] [Indexed: 02/06/2023]
Abstract
The Ca2+-independent phospholipases, designated as group VI iPLA2s, also referred to as PNPLAs due to their shared homology with patatin, include the β, γ, δ, ε, ζ, and η forms of the enzyme. The iPLA2s are ubiquitously expressed, share a consensus GXSXG catalytic motif, and exhibit organelle/cell-specific localization. Among the iPLA2s, iPLA2β has received wide attention as it is recognized to be involved in membrane remodeling, cell proliferation, cell death, and signal transduction. Ongoing studies implicate participation of iPLA2β in a variety of disease processes including cancer, cardiovascular abnormalities, glaucoma, and peridonditis. This review will focus on iPLA2β and its links to male fertility, neurological disorders, metabolic disorders, and inflammation.
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Affiliation(s)
- John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Tayleur D White
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America
| | - Alexander J Nelson
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America
| | - Xiaoyong Lei
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America
| | - Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America.
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Lou B, Liu Q, Hou J, Kabir I, Liu P, Ding T, Dong J, Mo M, Ye D, Chen Y, Bui HH, Roth K, Cao Y, Jiang XC. 2-Hydroxy-oleic acid does not activate sphingomyelin synthase activity. J Biol Chem 2018; 293:18328-18336. [PMID: 30305392 DOI: 10.1074/jbc.ra118.005904] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/02/2018] [Indexed: 11/06/2022] Open
Abstract
2-Hydroxy-oleic acid (2OHOA) is a potent anticancer drug that induces cancer cell cycle arrest and apoptosis. Previous studies have suggested that 2OHOA's anticancer effect is mediated by SMS activation in cancer cells, including A549 and U118 cells. To confirm this phenomenon, in this study, we treated both A549 and U118 cells with 2OHOA and measured SMS activity. To our surprise, we found neither 2OHOA-mediated SMS activation nor sphingomyelin accumulation in the cells. However, we noted that 2OHOA significantly reduces phosphatidylcholine in these cells. We also did not observe 2OHOA-mediated SMS activation in mouse tissue homogenates. Importantly, 2OHOA inhibited rather than activated recombinant SMS1 (rSMS1) and rSMS2 in a dose-dependent fashion. Intra-gastric treatment of C57BL/6J mice with 2OHOA for 10 days had no effects on liver and small intestine SMS activities and plasma sphingomyelin levels. The treatment inhibited lysophosphatidylcholine acyltransferase (LPCAT) activity, consistent with the aforementioned reduction in plasma phosphatidylcholine. Because total cellular phosphatidylcholine is used as a predictive biomarker for monitoring tumor responses, the previously reported 2OHOA-mediated cancer suppression could be related to this phosphatidylcholine reduction, which may influence cell membrane structure and properties. We conclude that 2OHOA is not a SMS activator and that its anticancer property may be related to an effect on phosphatidylcholine metabolism.
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Affiliation(s)
- Bin Lou
- From the School of Pharmacy, Fudan University, Shanghai 201203, China,.
| | - Qi Liu
- From the School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Jiahui Hou
- From the School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Inamul Kabir
- the Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York 11203
| | - Peipei Liu
- From the School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Tingbo Ding
- From the School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Jibin Dong
- From the School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Mingguang Mo
- From the School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Deyong Ye
- From the School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Yang Chen
- the Institute of Precision Medicine, Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200000, China
| | - Hai H Bui
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, Indiana 46285, and
| | - Kenneth Roth
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, Indiana 46285, and
| | - Yu Cao
- the Institute of Precision Medicine, Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200000, China,.
| | - Xian-Cheng Jiang
- From the School of Pharmacy, Fudan University, Shanghai 201203, China,; the Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York 11203,; the Molecular and Cellular Cardiology Program, Veterans Affairs New York Harbor Healthcare System, Brooklyn, New York 11209
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13
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Iliadi KG, Gluscencova OB, Iliadi N, Boulianne GL. Mutations in the Drosophila homolog of human PLA2G6 give rise to age-dependent loss of psychomotor activity and neurodegeneration. Sci Rep 2018; 8:2939. [PMID: 29440694 PMCID: PMC5811537 DOI: 10.1038/s41598-018-21343-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 12/20/2017] [Indexed: 12/24/2022] Open
Abstract
Infantile neuroaxonal dystrophy (INAD) is a fatal neurodegenerative disorder that typically begins within the first few years of life and leads to progressive impairment of movement and cognition. Several years ago, it was shown that >80% of patients with INAD have mutations in the phospholipase gene, PLA2G6. Interestingly, mutations in PLA2G6 are also causative in two other related neurodegenerative diseases, atypical neuroaxonal dystrophy and Dystonia-parkinsonism. While all three disorders give rise to similar defects in movement and cognition, some defects are unique to a specific disorder. At present, the cellular mechanisms underlying PLA2G6-associated neuropathology are poorly understood and there is no cure or treatment that can delay disease progression. Here, we show that loss of iPLA2-VIA, the Drosophila homolog of PLA2G6, gives rise to age-dependent defects in climbing and spontaneous locomotion. Moreover, using a newly developed assay, we show that iPLA2-VIA mutants also display impairments in fine-tune motor movements, motor coordination and psychomotor learning, which are distinct features of PLA2G6-associated disease in humans. Finally, we show that iPLA2-VIA mutants exhibit increased sensitivity to oxidative stress, progressive neurodegeneration and a severely reduced lifespan. Altogether, these data demonstrate that Drosophila iPLA2-VIA mutants provide a useful model to study human PLA2G6-associated neurodegeneration.
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Affiliation(s)
- Konstantin G Iliadi
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada.
| | - Oxana B Gluscencova
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada
| | - Natalia Iliadi
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada
| | - Gabrielle L Boulianne
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada. .,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.
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14
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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: 9.9] [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.
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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.
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15
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Smani T, Domínguez-Rodriguez A, Callejo-García P, Rosado JA, Avila-Medina J. Phospholipase A2 as a Molecular Determinant of Store-Operated Calcium Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:111-31. [PMID: 27161227 DOI: 10.1007/978-3-319-26974-0_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Activation of phospholipases A2 (PLA2) leads to the generation of biologically active lipid products that can affect numerous cellular events. Ca(2+)-independent PLA2 (iPLA2), also called group VI phospholipase A2, is one of the main types forming the superfamily of PLA2. Beside of its role in phospholipid remodeling, iPLA2 has been involved in intracellular Ca(2+) homeostasis regulation. Several studies proposed iPLA2 as an essential molecular player of store operated Ca(2+) entry (SOCE) in a large number of excitable and non-excitable cells. iPLA2 activation releases lysophosphatidyl products, which were suggested as agonists of store operated calcium channels (SOCC) and other TRP channels. Herein, we will review the important role of iPLA2 on the intracellular Ca(2+) handling focusing on its role in SOCE regulation and its implication in physiological and/or pathological processes.
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Affiliation(s)
- Tarik Smani
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain.
| | - Alejandro Domínguez-Rodriguez
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain
| | - Paula Callejo-García
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain
| | - Juan A Rosado
- Departamento de Fisiología, University of Extremadura, Cáceres, Spain
| | - Javier Avila-Medina
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain
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16
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Leis HJ, Windischhofer W. Calcium-independent phospholipases A2 in murine osteoblastic cells and their inhibition by bromoenol lactone: impact on arachidonate dynamics and prostaglandin synthesis. J Enzyme Inhib Med Chem 2015; 31:1203-13. [PMID: 26609885 DOI: 10.3109/14756366.2015.1114929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
CONTEXT Bromoenol lactone (BEL) is an inhibitor of group VI phospholipases (iPLA2s), but has been shown to have severe side effects. OBJECTIVE iPLA2 characterization in osteoblasts and effect of BEL on prostaglandin (PG) E2 formation. METHODS iPLA2 expression: RT-PCR, Western Blotting. PGE2 formation: GC-MS after stimulation, treatment with inhibitors or gene silencing. Arachidonate (AA) reacylation into phospholipids, inhibitor reaction products, PGHS-1 modification proteomic analysis: HR-LC-MS/MS. AA accumulation: (14)C-AA. RESULTS iPLA2ß and iPLA2γ were expressed and functionally active. BEL inhibition up to 20 μM caused AA accumulation and enhanced PGE2 formation, followed by a decrease at higher concentrations. BEL reacted with intracellular cysteine and GSH leading to GSH depletion and oxidative stress. DISCUSSION Initial PGE2 enhancement after BEL inhibition is due to iPLA2-independent accumulation of AA. GSH depletion caused by high BEL concentrations is responsible for the decrease in PGE2 production. CONCLUSION BEL must be used with caution in a cellular environment due to conditions of extreme oxidative stress.
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Affiliation(s)
- Hans Jörg Leis
- a University Hospital of Youth and Adolescence Medicine, Medical University of Graz, Research Unit of Analytical Mass Spectrometry, Cell Biology and Biochemistry of Inborn Errors of Metabolism , Graz , Austria
| | - Werner Windischhofer
- a University Hospital of Youth and Adolescence Medicine, Medical University of Graz, Research Unit of Analytical Mass Spectrometry, Cell Biology and Biochemistry of Inborn Errors of Metabolism , Graz , Austria
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17
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Ong WY, Farooqui T, Kokotos G, Farooqui AA. Synthetic and natural inhibitors of phospholipases A2: their importance for understanding and treatment of neurological disorders. ACS Chem Neurosci 2015; 6:814-31. [PMID: 25891385 DOI: 10.1021/acschemneuro.5b00073] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Phospholipases A2 (PLA2) are a diverse group of enzymes that hydrolyze membrane phospholipids into arachidonic acid and lysophospholipids. Arachidonic acid is metabolized to eicosanoids (prostaglandins, leukotrienes, thromboxanes), and lysophospholipids are converted to platelet-activating factors. These lipid mediators play critical roles in the initiation, maintenance, and modulation of neuroinflammation and oxidative stress. Neurological disorders including excitotoxicity; traumatic nerve and brain injury; cerebral ischemia; Alzheimer's disease; Parkinson's disease; multiple sclerosis; experimental allergic encephalitis; pain; depression; bipolar disorder; schizophrenia; and autism are characterized by oxidative stress, inflammatory reactions, alterations in phospholipid metabolism, accumulation of lipid peroxides, and increased activities of brain phospholipase A2 isoforms. Several old and new synthetic inhibitors of PLA2, including fatty acid trifluoromethyl ketones; methyl arachidonyl fluorophosphonate; bromoenol lactone; indole-based inhibitors; pyrrolidine-based inhibitors; amide inhibitors, 2-oxoamides; 1,3-disubstituted propan-2-ones and polyfluoroalkyl ketones as well as phytochemical based PLA2 inhibitors including curcumin, Ginkgo biloba and Centella asiatica extracts have been discovered and used for the treatment of neurological disorders in cell culture and animal model systems. The purpose of this review is to summarize information on selective and potent synthetic inhibitors of PLA2 as well as several PLA2 inhibitors from plants, for treatment of oxidative stress and neuroinflammation associated with the pathogenesis of neurological disorders.
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Affiliation(s)
- Wei-Yi Ong
- Department
of Anatomy, National University of Singapore, Singapore 119260, Singapore
| | - Tahira Farooqui
- Department
of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210, United States
| | - George Kokotos
- Laboratory
of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis,
Athens 15771, Greece
| | - Akhlaq A. Farooqui
- Department
of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210, United States
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18
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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: 146] [Impact Index Per Article: 14.6] [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.
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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
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19
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Mouchlis VD, Bucher D, McCammon JA, Dennis EA. Membranes serve as allosteric activators of phospholipase A2, enabling it to extract, bind, and hydrolyze phospholipid substrates. Proc Natl Acad Sci U S A 2015; 112:E516-25. [PMID: 25624474 PMCID: PMC4330758 DOI: 10.1073/pnas.1424651112] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Defining the molecular details and consequences of the association of water-soluble proteins with membranes is fundamental to understanding protein-lipid interactions and membrane functioning. Phospholipase A2 (PLA2) enzymes, which catalyze the hydrolysis of phospholipid substrates that compose the membrane bilayers, provide the ideal system for studying protein-lipid interactions. Our study focuses on understanding the catalytic cycle of two different human PLA2s: the cytosolic Group IVA cPLA2 and calcium-independent Group VIA iPLA2. Computer-aided techniques guided by deuterium exchange mass spectrometry data, were used to create structural complexes of each enzyme with a single phospholipid substrate molecule, whereas the substrate extraction process was studied using steered molecular dynamics simulations. Molecular dynamic simulations of the enzyme-substrate-membrane systems revealed important information about the mechanisms by which these enzymes associate with the membrane and then extract and bind their phospholipid substrate. Our data support the hypothesis that the membrane acts as an allosteric ligand that binds at the allosteric site of the enzyme's interfacial surface, shifting its conformation from a closed (inactive) state in water to an open (active) state at the membrane interface.
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Affiliation(s)
| | | | - J Andrew McCammon
- Departments of Pharmacology and Chemistry and Biochemistry, and Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093-0601
| | - Edward A Dennis
- Departments of Pharmacology and Chemistry and Biochemistry, and
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20
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Ali T, Kokotos G, Magrioti V, Bone RN, Mobley JA, Hancock W, Ramanadham S. Characterization of FKGK18 as inhibitor of group VIA Ca2+-independent phospholipase A2 (iPLA2β): candidate drug for preventing beta-cell apoptosis and diabetes. PLoS One 2013; 8:e71748. [PMID: 23977134 PMCID: PMC3748103 DOI: 10.1371/journal.pone.0071748] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/30/2013] [Indexed: 01/27/2023] Open
Abstract
Ongoing studies suggest an important role for iPLA2β in a multitude of biological processes and it has been implicated in neurodegenerative, skeletal and vascular smooth muscle disorders, bone formation, and cardiac arrhythmias. Thus, identifying an iPLA2βinhibitor that can be reliably and safely used in vivo is warranted. Currently, the mechanism-based inhibitor bromoenol lactone (BEL) is the most widely used to discern the role of iPLA2β in biological processes. While BEL is recognized as a more potent inhibitor of iPLA2 than of cPLA2 or sPLA2, leading to its designation as a "specific" inhibitor of iPLA2, it has been shown to also inhibit non-PLA2 enzymes. A potential complication of its use is that while the S and R enantiomers of BEL exhibit preference for cytosol-associated iPLA2β and membrane-associated iPLA2γ, respectively, the selectivity is only 10-fold for both. In addition, BEL is unstable in solution, promotes irreversible inhibition, and may be cytotoxic, making BEL not amenable for in vivo use. Recently, a fluoroketone (FK)-based compound (FKGK18) was described as a potent inhibitor of iPLA2β. Here we characterized its inhibitory profile in beta-cells and find that FKGK18: (a) inhibits iPLA2β with a greater potency (100-fold) than iPLA2γ, (b) inhibition of iPLA2β is reversible, (c) is an ineffective inhibitor of α-chymotrypsin, and (d) inhibits previously described outcomes of iPLA2β activation including (i) glucose-stimulated insulin secretion, (ii) arachidonic acid hydrolysis; as reflected by PGE2 release from human islets, (iii) ER stress-induced neutral sphingomyelinase 2 expression, and (iv) ER stress-induced beta-cell apoptosis. These findings suggest that FKGK18 is similar to BEL in its ability to inhibit iPLA2β. Because, in contrast to BEL, it is reversible and not a non-specific inhibitor of proteases, it is suggested that FKGK18 is more ideal for ex vivo and in vivo assessments of iPLA2β role in biological functions.
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Affiliation(s)
- Tomader Ali
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
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21
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Riku Y, Ikeuchi T, Yoshino H, Mimuro M, Mano K, Goto Y, Hattori N, Sobue G, Yoshida M. Extensive aggregation of α-synuclein and tau in juvenile-onset neuroaxonal dystrophy: an autopsied individual with a novel mutation in the PLA2G6 gene-splicing site. Acta Neuropathol Commun 2013; 1:12. [PMID: 24252552 PMCID: PMC3893443 DOI: 10.1186/2051-5960-1-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Accepted: 04/05/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Infantile neuroaxonal dystrophy (INAD) is a rare autosomal-recessive neurodegenerative disorder. Patients with INAD usually show neurological symptoms with infant onset and die in childhood. Recently, it was reported that mutations in the PLA2G6 gene cause INAD, but neuropathological analysis of genetically confirmed individuals with neuroaxonal dystrophy has been limited. RESULTS Here, we report a Japanese individual with neuroaxonal dystrophy associated with compound heterozygous mutations in the PLA2G6 gene. A novel splice-site mutation resulting in skipping and missense mutations (p.R538C) in exon 9 was identified in the patient. This patient initially presented with cerebellar ataxia at the age of 3 years, which was followed by symptoms of mental retardation, extrapyramidal signs, and epileptic seizure. The patient survived until 20 years of age. Neuropathological findings were characterized by numerous axonal spheroids, brain iron deposition, cerebellar neuronal loss, phosphorylated alpha-synuclein-positive Lewy bodies (LBs), and phosphorylated-tau-positive neurofibrillary tangles. In particular, LB pathology exhibited a unique distribution with extremely severe cortical involvement. CONCLUSIONS Our results support a genetic clinical view that compound heterozygous mutations with potential residual protein function are associated with a relatively mild phenotype. Moreover, the severe LB pathology suggests that dysfunction of the PLA2G6 gene primarily contributes to LB formation.
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22
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Association of the iPLA2β gene with bipolar disorder and assessment of its interaction with TRPM2 gene polymorphisms. Psychiatr Genet 2013; 23:86-9. [DOI: 10.1097/ypg.0b013e32835d700d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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23
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Lei X, Zhang S, Bohrer A, Barbour SE, Ramanadham S. Role of calcium-independent phospholipase A(2)β in human pancreatic islet β-cell apoptosis. Am J Physiol Endocrinol Metab 2012; 303:E1386-95. [PMID: 23074238 PMCID: PMC3774083 DOI: 10.1152/ajpendo.00234.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Death of β-cells due to apoptosis is an important contributor to β-cell dysfunction in both type 1 and type 2 diabetes mellitus. Previously, we described participation of the Group VIA Ca(2+)-independent phospholipase A(2) (iPLA(2)β) in apoptosis of insulinoma cells due to ER stress. To examine whether islet β-cells are similarly susceptible to ER stress and undergo iPLA(2)β-mediated apoptosis, we assessed the ER stress response in human pancreatic islets. Here, we report that the iPLA(2)β protein is expressed predominantly in the β-cells of human islets and that thapsigargin-induced ER stress promotes β-cell apoptosis, as reflected by increases in activated caspase-3 in the β-cells. Furthermore, we demonstrate that ER stress is associated with increases in islet iPLA(2)β message, protein, and activity, iPLA(2)β-dependent induction of neutral sphingomyelinase and ceramide accumulation, and subsequent loss of mitochondrial membrane potential. We also observe that basal activated caspase-3 increases with age, raising the possibility that β-cells in older human subjects have a greater susceptibility to undergo apoptotic cell death. These findings reveal for the first time expression of iPLA(2)β protein in human islet β-cells and that induction of iPLA(2)β during ER stress contributes to human islet β-cell apoptosis. We hypothesize that modulation of iPLA(2)β activity might reduce β-cell apoptosis and this would be beneficial in delaying or preventing β-cell dysfunction associated with diabetes.
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Affiliation(s)
- Xiaoyong Lei
- Dept. of Cell, Developmental, and Integrative Biology, Univ. of Alabama at Birmingham, Birmingham, AL 35294, USA
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24
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Tanaka K, Siddiqi NJ, Alhomida AS, Farooqui AA, Ong WY. Differential regulation of cPLA2 and iPLA2 expression in the brain. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11515-012-9247-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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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: 1.7] [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.
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Affiliation(s)
- Paul Glynn
- Department of Cell Physiology & Pharmacology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK.
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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.
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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
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Li Z, Ding T, Pan X, Li Y, Li R, Sanders PE, Kuo MS, Hussain MM, Cao G, Jiang XC. Lysophosphatidylcholine acyltransferase 3 knockdown-mediated liver lysophosphatidylcholine accumulation promotes very low density lipoprotein production by enhancing microsomal triglyceride transfer protein expression. J Biol Chem 2012; 287:20122-31. [PMID: 22511767 DOI: 10.1074/jbc.m111.334664] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
After de novo biosynthesis phospholipids undergo extensive remodeling by the Lands' cycle. Enzymes involved in phospholipid biosynthesis have been studied extensively but not those involved in reacylation of lysophosphopholipids. One key enzyme in the Lands' cycle is fatty acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT), which utilizes lysophosphatidylcholine (LysoPC) and fatty acyl-CoA to produce various phosphatidylcholine (PC) species. Four isoforms of LPCAT have been identified. In this study we found that LPCAT3 is the major hepatic isoform, and its knockdown significantly reduces hepatic LPCAT activity. Moreover, we report that hepatic LPCAT3 knockdown increases certain species of LysoPCs and decreases certain species of PC. A surprising observation was that LPCAT3 knockdown significantly reduces hepatic triglycerides. Despite this, these mice had higher plasma triglyceride and apoB levels. Lipoprotein production studies indicated that reductions in LPCAT3 enhanced assembly and secretion of triglyceride-rich apoB-containing lipoproteins. Furthermore, these mice had higher microsomal triglyceride transfer protein (MTP) mRNA and protein levels. Mechanistic studies in hepatoma cells revealed that LysoPC enhances secretion of apoB but not apoA-I in a concentration-dependent manner. Moreover, LysoPC increased MTP mRNA, protein, and activity. In short, these results indicate that hepatic LPCAT3 modulates VLDL production by regulating LysoPC levels and MTP expression.
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Affiliation(s)
- Zhiqiang Li
- Molecular and Cellular Cardiology Program, Veterans Affairs New York Harbor Healthcare System, Brooklyn, New York 11209, USA
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Song H, Wohltmann M, Tan M, Bao S, Ladenson JH, Turk J. Group VIA PLA2 (iPLA2β) is activated upstream of p38 mitogen-activated protein kinase (MAPK) in pancreatic islet β-cell signaling. J Biol Chem 2012; 287:5528-41. [PMID: 22194610 PMCID: PMC3285329 DOI: 10.1074/jbc.m111.285114] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 12/21/2011] [Indexed: 01/09/2023] Open
Abstract
Group VIA phospholipase A(2) (iPLA(2)β) in pancreatic islet β-cells participates in glucose-stimulated insulin secretion and sarco(endo)plasmic reticulum ATPase (SERCA) inhibitor-induced apoptosis, and both are attenuated by pharmacologic or genetic reductions in iPLA(2)β activity and amplified by iPLA(2)β overexpression. While exploring signaling events that occur downstream of iPLA(2)β activation, we found that p38 MAPK is activated by phosphorylation in INS-1 insulinoma cells and mouse pancreatic islets, that this increases with iPLA(2)β expression level, and that it is stimulated by the iPLA(2)β reaction product arachidonic acid. The insulin secretagogue D-glucose also stimulates β-cell p38 MAPK phosphorylation, and this is prevented by the iPLA(2)β inhibitor bromoenol lactone. Insulin secretion induced by d-glucose and forskolin is amplified by overexpressing iPLA(2)β in INS-1 cells and in mouse islets, and the p38 MAPK inhibitor PD169316 prevents both responses. The SERCA inhibitor thapsigargin also stimulates phosphorylation of both β-cell MAPK kinase isoforms and p38 MAPK, and bromoenol lactone prevents both events. Others have reported that iPLA(2)β products activate Rho family G-proteins that promote MAPK kinase activation via a mechanism inhibited by Clostridium difficile toxin B, which we find to inhibit thapsigargin-induced β-cell p38 MAPK phosphorylation. Thapsigargin-induced β-cell apoptosis and ceramide generation are also prevented by the p38 MAPK inhibitor PD169316. These observations indicate that p38 MAPK is activated downstream of iPLA(2)β in β-cells incubated with insulin secretagogues or thapsigargin, that this requires prior iPLA(2)β activation, and that p38 MAPK is involved in the β-cell functional responses of insulin secretion and apoptosis in which iPLA(2)β participates.
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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
| | - Shunzhong Bao
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, and
| | - Jack H. Ladenson
- the 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
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29
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Zhao Z, Wang J, Zhao C, Bi W, Yue Z, Ma ZA. Genetic ablation of PLA2G6 in mice leads to cerebellar atrophy characterized by Purkinje cell loss and glial cell activation. PLoS One 2011; 6:e26991. [PMID: 22046428 PMCID: PMC3203935 DOI: 10.1371/journal.pone.0026991] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 10/07/2011] [Indexed: 12/15/2022] Open
Abstract
Infantile neuroaxonal dystrophy (INAD) is a progressive, autosomal recessive neurodegenerative disease characterized by axonal dystrophy, abnormal iron deposition and cerebellar atrophy. This disease was recently mapped to PLA2G6, which encodes group VI Ca(2+)-independent phospholipase A(2) (iPLA(2) or iPLA(2)β). Here we show that genetic ablation of PLA2G6 in mice (iPLA(2)β(-/-)) leads to the development of cerebellar atrophy by the age of 13 months. Atrophied cerebella exhibited significant loss of Purkinje cells, as well as reactive astrogliosis, the activation of microglial cells, and the pronounced up-regulation of the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Moreover, glial cell activation and the elevation in TNF-α and IL-1β expression occurred before apparent cerebellar atrophy. Our findings indicate that the absence of PLA2G6 causes neuroinflammation and Purkinje cell loss and ultimately leads to cerebellar atrophy. Our study suggests that iPLA(2)β(-/-) mice are a valuable model for cerebellar atrophy in INAD and that early anti-inflammatory therapy may help slow the progression of cerebellar atrophy in this deadly neurodegenerative disease.
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Affiliation(s)
- Zhengshan Zhao
- Division of Experimental Diabetes and Aging, Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Jing Wang
- Department of Neurology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Chunying Zhao
- Division of Experimental Diabetes and Aging, Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Weina Bi
- Division of Experimental Diabetes and Aging, Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Zhenyu Yue
- Department of Neurology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Zhongmin Alex Ma
- Division of Experimental Diabetes and Aging, Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
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Dennis EA, Cao J, Hsu YH, Magrioti V, Kokotos G. Phospholipase A2 enzymes: physical structure, biological function, disease implication, chemical inhibition, and therapeutic intervention. Chem Rev 2011; 111:6130-85. [PMID: 21910409 PMCID: PMC3196595 DOI: 10.1021/cr200085w] [Citation(s) in RCA: 861] [Impact Index Per Article: 61.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Edward A. Dennis
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Jian Cao
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Yuan-Hao Hsu
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Victoria Magrioti
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
| | - George Kokotos
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
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31
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Long JZ, Cravatt BF. The metabolic serine hydrolases and their functions in mammalian physiology and disease. Chem Rev 2011; 111:6022-63. [PMID: 21696217 DOI: 10.1021/cr200075y] [Citation(s) in RCA: 321] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jonathan Z Long
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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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: 24.5] [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.
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Affiliation(s)
- Makoto Murakami
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
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Engel LA, Jing Z, O'Brien DE, Sun M, Kotzbauer PT. Catalytic function of PLA2G6 is impaired by mutations associated with infantile neuroaxonal dystrophy but not dystonia-parkinsonism. PLoS One 2010; 5:e12897. [PMID: 20886109 PMCID: PMC2944820 DOI: 10.1371/journal.pone.0012897] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 08/31/2010] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Mutations in the PLA2G6 gene have been identified in autosomal recessive neurodegenerative diseases classified as infantile neuroaxonal dystrophy (INAD), neurodegeneration with brain iron accumulation (NBIA), and dystonia-parkinsonism. These clinical syndromes display two significantly different disease phenotypes. NBIA and INAD are very similar, involving widespread neurodegeneration that begins within the first 1-2 years of life. In contrast, patients with dystonia-parkinsonism present with a parkinsonian movement disorder beginning at 15 to 30 years of age. The PLA2G6 gene encodes the PLA2G6 enzyme, also known as group VIA calcium-independent phospholipase A(2), which has previously been shown to hydrolyze the sn-2 acyl chain of phospholipids, generating free fatty acids and lysophospholipids. METHODOLOGY/PRINCIPAL FINDINGS We produced purified recombinant wildtype (WT) and mutant human PLA2G6 proteins and examined their catalytic function using in vitro assays with radiolabeled lipid substrates. We find that human PLA2G6 enzyme hydrolyzes both phospholipids and lysophospholipids, releasing free fatty acids. Mutations associated with different disease phenotypes have different effects on catalytic activity. Mutations associated with INAD/NBIA cause loss of enzyme activity, with mutant proteins exhibiting less than 20% of the specific activity of WT protein in both lysophospholipase and phospholipase assays. In contrast, mutations associated with dystonia-parkinsonism do not impair catalytic activity, and two mutations produce a significant increase in specific activity for phospholipid but not lysophospholipid substrates. CONCLUSIONS/SIGNIFICANCE These results indicate that different alterations in PLA2G6 function produce the different disease phenotypes of NBIA/INAD and dystonia-parkinsonism. INAD/NBIA is caused by loss of the ability of PLA2G6 to catalyze fatty acid release from phospholipids, which predicts accumulation of PLA2G6 phospholipid substrates and provides a mechanistic explanation for the accumulation of membranes in neuroaxonal spheroids previously observed in histopathological studies of INAD/NBIA. In contrast, dystonia-parkinsonism mutations do not appear to directly impair catalytic function, but may modify substrate preferences or regulatory mechanisms for PLA2G6.
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Affiliation(s)
- Laura A. Engel
- Departments of Neurology and Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Zheng Jing
- Departments of Neurology and Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Daniel E. O'Brien
- Departments of Neurology and Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Mengyang Sun
- Departments of Neurology and Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Paul T. Kotzbauer
- Departments of Neurology and Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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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: 0.7] [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.
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Affiliation(s)
- Haowei Song
- Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St Louis, Missouri 63110, USA
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Song H, Bao S, Lei X, Jin C, Zhang S, Turk J, Ramanadham S. Evidence for proteolytic processing and stimulated organelle redistribution of iPLA(2)beta. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1801:547-58. [PMID: 20132906 PMCID: PMC2848069 DOI: 10.1016/j.bbalip.2010.01.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 12/24/2009] [Accepted: 01/19/2010] [Indexed: 12/31/2022]
Abstract
Over the past decade, important roles for the 84-88kDa Group VIA Ca(2+)-independent phospholipase A(2) (iPLA(2)beta) in various organs have been described. We demonstrated that iPLA(2)beta participates in insulin secretion, insulinoma cells and native pancreatic islets express full-length and truncated isoforms of iPLA(2)beta, and certain stimuli promote perinuclear localization of iPLA(2)beta. To gain a better understanding of its mobilization, iPLA(2)beta was expressed in INS-1 cells as a fusion protein with EGFP, enabling detection of subcellular localization of iPLA(2)beta by monitoring EGFP fluorescence. Cells stably-transfected with fusion protein expressed nearly 5-fold higher catalytic iPLA(2)beta activity than control cells transfected with EGFP cDNA alone, indicating that co-expression of EGFP does not interfere with manifestation of iPLA(2)beta activity. Dual fluorescence monitoring of EGFP and organelle Trackers combined with immunoblotting analyses revealed expression of truncated iPLA(2)beta isoforms in separate subcellular organelles. Exposure to secretagogues and induction of ER stress are known to activate iPLA(2)beta in beta-cells and we find here that these stimuli promote differential localization of iPLA(2)beta in subcellular organelles. Further, mass spectrometric analyses identified iPLA(2)beta variants from which N-terminal residues were removed. Collectively, these findings provide evidence for endogenous proteolytic processing of iPLA(2)beta and redistribution of iPLA(2)beta variants in subcellular compartments. It might be proposed that in vivo processing of iPLA(2)beta facilitates its participation in multiple biological processes.
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Affiliation(s)
- Haowei Song
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, U.S.A
| | - Shunzhong Bao
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, U.S.A
| | - Xiaoyong Lei
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, U.S.A
| | - Chun Jin
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, U.S.A
| | - Sheng Zhang
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, U.S.A
| | - John Turk
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, U.S.A
| | - Sasanka Ramanadham
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, U.S.A
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The Study of The Interaction Between Parkin and OGCP*. PROG BIOCHEM BIOPHYS 2010. [DOI: 10.3724/sp.j.1206.2009.00349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Lei X, Barbour SE, Ramanadham S. Group VIA Ca2+-independent phospholipase A2 (iPLA2beta) and its role in beta-cell programmed cell death. Biochimie 2010; 92:627-37. [PMID: 20083151 DOI: 10.1016/j.biochi.2010.01.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 01/11/2010] [Indexed: 01/09/2023]
Abstract
Activation of phospholipases A(2) (PLA(2)s) leads to the generation of biologically active lipid mediators that can affect numerous cellular events. The Group VIA Ca(2+)-independent PLA(2), designated iPLA(2)beta, is active in the absence of Ca(2+), activated by ATP, and inhibited by the bromoenol lactone suicide inhibitor (BEL). Over the past 10-15 years, studies using BEL have demonstrated that iPLA(2)beta participates in various biological processes and the recent availability of mice in which iPLA(2)beta expression levels have been genetically-modified are extending these findings. Work in our laboratory suggests that iPLA(2)beta activates a unique signaling cascade that promotes beta-cell apoptosis. This pathway involves iPLA(2)beta dependent induction of neutral sphingomyelinase, production of ceramide, and activation of the intrinsic pathway of apoptosis. There is a growing body of literature supporting beta-cell apoptosis as a major contributor to the loss of beta-cell mass associated with the onset and progression of Type 1 and Type 2 diabetes mellitus. This underscores a need to gain a better understanding of the molecular mechanisms underlying beta-cell apoptosis so that improved treatments can be developed to prevent or delay the onset and progression of diabetes mellitus. Herein, we offer a general review of Group VIA Ca(2+)-independent PLA(2) (iPLA(2)beta) followed by a more focused discussion of its participation in beta-cell apoptosis. We suggest that iPLA(2)beta-derived products trigger pathways which can lead to beta-cell apoptosis during the development of diabetes.
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Affiliation(s)
- Xiaoyong Lei
- Department of Medicine, Mass Spectrometry Resource and Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
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Coupled calcium and zinc dyshomeostasis and oxidative stress in cardiac myocytes and mitochondria of rats with chronic aldosteronism. J Cardiovasc Pharmacol 2009; 53:414-23. [PMID: 19333130 DOI: 10.1097/fjc.0b013e3181a15e77] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A dyshomeostasis of extra- and intracellular Ca(2+) and Zn(2+) occurs in rats receiving chronic aldosterone/salt treatment (ALDOST). Herein, we hypothesized that the dyshomeostasis of intracellular Ca(2+) and Zn(2+) is intrinsically coupled that alters the redox state of cardiac myocytes and mitochondria, with Ca(2+) serving as a pro-oxidant and Zn(2+) as an antioxidant. Toward this end, we harvested hearts from rats receiving 4 weeks of ALDOST alone or cotreatment with either spironolactone (Spiro), an aldosterone receptor antagonist, or amlodipine (Amlod), an L-type Ca(2+) channel blocker, and from age/sex-matched untreated controls. In each group, we monitored cardiomyocyte [Ca(2+)]i and [Zn(2+)]i and mitochondrial [Ca(2+)]m and [Zn(2+)]m; biomarkers of oxidative stress and antioxidant defenses; expression of Zn transporters, Zip1 and ZnT-1; metallothionein-1, a Zn(2+)-binding protein; and metal response element transcription factor-1, a [Zn(2+)]i sensor and regulator of antioxidant defenses. Compared with controls, at 4-week ALDOST, we found the following: (a) increased [Ca(2+)]i and [Zn(2+)]i, together with increased [Ca(2+)]m and [Zn(2+)]m, each of which could be prevented by Spiro and attenuated with Amlod; (b) increased levels of 3-nitrotyrosine and 4-hydroxy-2-nonenal in cardiomyocytes, together with increased H(2)O(2) production, malondialdehyde, and oxidized glutathione in mitochondria that were coincident with increased activities of Cu/Zn superoxide dismutase and glutathione peroxidase; and (c) increased expression of metallothionein-1, Zip1 and ZnT-1, and metal response element transcription factor-1, attenuated by Spiro. Thus, an intrinsically coupled dyshomeostasis of intracellular Ca(2+) and Zn(2+) occurs in cardiac myocytes and mitochondria in rats receiving ALDOST, where it serves to alter their redox state through a respective induction of oxidative stress and generation of antioxidant defenses. The importance of therapeutic strategies that can uncouple these two divalent cations and modulate their ratio in favor of sustained antioxidant defenses is therefore suggested.
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Falchi M, Bataille V, Hayward NK, Duffy DL, Bishop JAN, Pastinen T, Cervino A, Zhao ZZ, Deloukas P, Soranzo N, Elder DE, Barrett JH, Martin NG, Bishop DT, Montgomery GW, Spector TD. Genome-wide association study identifies variants at 9p21 and 22q13 associated with development of cutaneous nevi. Nat Genet 2009; 41:915-9. [PMID: 19578365 PMCID: PMC3080738 DOI: 10.1038/ng.410] [Citation(s) in RCA: 186] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 06/09/2009] [Indexed: 11/08/2022]
Abstract
A high melanocytic nevi count is the strongest known risk factor for cutaneous melanoma. We conducted a genome-wide association study for nevus count using 297,108 SNPs in 1,524 twins, with validation in an independent cohort of 4,107 individuals. We identified strongly associated variants in MTAP, a gene adjacent to the familial melanoma susceptibility locus CDKN2A on 9p21 (rs4636294, combined P = 3.4 x 10(-15)), as well as in PLA2G6 on 22q13.1 (rs2284063, combined P = 3.4 x 10(-8)). In addition, variants in these two loci showed association with melanoma risk in 3,131 melanoma cases from two independent studies, including rs10757257 at 9p21, combined P = 3.4 x 10(-8), OR = 1.23 (95% CI = 1.15-1.30) and rs132985 at 22q13.1, combined P = 2.6 x 10(-7), OR = 1.23 (95% CI = 1.15-1.30). This provides the first report of common variants associated to nevus number and demonstrates association of these variants with melanoma susceptibility.
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Affiliation(s)
- Mario Falchi
- Department of Twin Research & Genetic Epidemiology, Kings College London, St. Thomas' Hospital Campus, London, UK.
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40
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Hsu YH, Burke JE, Li S, Woods VL, Dennis EA. Localizing the membrane binding region of Group VIA Ca2+-independent phospholipase A2 using peptide amide hydrogen/deuterium exchange mass spectrometry. J Biol Chem 2009; 284:23652-61. [PMID: 19556238 DOI: 10.1074/jbc.m109.021857] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Group VIA-2 Ca(2+)-independent phospholipase A(2) (GVIA-2 iPLA(2)) is composed of seven consecutive N-terminal ankyrin repeats, a linker region, and a C-terminal phospholipase catalytic domain. No structural information exists for this enzyme, and no information is known about the membrane binding surface. We carried out deuterium exchange experiments with the GVIA-2 iPLA(2) in the presence of both phospholipid substrate and the covalent inhibitor methyl arachidonoyl fluorophosphonate and located regions in the protein that change upon lipid binding. No changes were seen in the presence of only methyl arachidonoyl fluorophosphonate. The region with the greatest change upon lipid binding was region 708-730, which showed a >70% decrease in deuteration levels at numerous time points. No decreases in exchange due to phospholipid binding were seen in the ankyrin repeat domain of the protein. To locate regions with changes in exchange on the enzyme, we constructed a computational homology model based on homologous structures. This model was validated by comparing the deuterium exchange results with the predicted structure. Our model combined with the deuterium exchange results in the presence of lipid substrate have allowed us to propose the first structural model of GVIA-2 iPLA(2) as well as the interfacial lipid binding region.
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Affiliation(s)
- Yuan-Hao Hsu
- Department of Chemistry, University of California, San Diego, La Jolla, California 92093-0601, USA
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41
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Cedars A, Jenkins CM, Mancuso DJ, Gross RW. Calcium-independent phospholipases in the heart: mediators of cellular signaling, bioenergetics, and ischemia-induced electrophysiologic dysfunction. J Cardiovasc Pharmacol 2009; 53:277-289. [PMID: 19390346 PMCID: PMC2684941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Myocardial function is intimately dependent on the precise spatiotemporal regulation of membrane-bound proteins and ion channels. Phospholipases play critical roles in the maintenance of membrane structure and function, thereby fundamentally integrating dynamic alterations in myocardial performance with membrane composition and dynamics. The major phospholipases in myocardium belong to a family of proteins known as calcium-independent phospholipases (iPLA2s). In addition to their role in maintaining normal membrane structure and function, iPLA2 catalytic activity results in the generation of a variety of lipid second messengers that facilitate cellular signaling. Through its multiple effects on cardiac myocyte bioenergetics, cellular signaling, and membrane function, the iPLA2 family of enzymes is of primary importance in modulating the pathologic sequelae of myocardial ischemia, diabetic cardiomyopathy, and remodeling during hemodynamic stress. This review will provide a brief overview of myocardial iPLA2s and their significance in cardiac pathology and physiology.
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Affiliation(s)
- Ari Cedars
- Divisions of Cardiology, Washington University School of Medicine, St. Louis, Missouri 63110
- Departments of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Christopher M. Jenkins
- Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
- Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - David J. Mancuso
- Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
- Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Richard W. Gross
- Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
- Departments of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
- Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Chemistry, Washington University, St. Louis 63130
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42
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Rosa AO, Rapoport SI. Intracellular- and extracellular-derived Ca(2+) influence phospholipase A(2)-mediated fatty acid release from brain phospholipids. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:697-705. [PMID: 19327408 DOI: 10.1016/j.bbalip.2009.03.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 03/01/2009] [Accepted: 03/11/2009] [Indexed: 02/01/2023]
Abstract
Docosahexaenoic acid (DHA) and arachidonic acid (AA) are found in high concentrations in brain cell membranes and are important for brain function and structure. Studies suggest that AA and DHA are hydrolyzed selectively from the sn-2 position of synaptic membrane phospholipids by Ca(2+)-dependent cytosolic phospholipase A(2) (cPLA(2)) and Ca(2+)-independent phospholipase A(2) (iPLA(2)), respectively, resulting in increased levels of the unesterified fatty acids and lysophospholipids. Cell studies also suggest that AA and DHA release depend on increased concentrations of Ca(2+), even though iPLA(2) has been thought to be Ca(2+)-independent. The source of Ca(2+) for activation of cPLA(2) is largely extracellular, whereas Ca(2+) released from the endoplasmic reticulum can activate iPLA(2) by a number of mechanisms. This review focuses on the role of Ca(2+) in modulating cPLA(2) and iPLA(2) activities in different conditions. Furthermore, a model is suggested in which neurotransmitters regulate the activity of these enzymes and thus the balanced and localized release of AA and DHA from phospholipid in the brain, depending on the primary source of the Ca(2+) signal.
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Affiliation(s)
- Angelo O Rosa
- Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
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43
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Carper MJ, Zhang S, Turk J, Ramanadham S. Skeletal muscle group VIA phospholipase A2 (iPLA2beta): expression and role in fatty acid oxidation. Biochemistry 2008; 47:12241-9. [PMID: 18937505 DOI: 10.1021/bi800923s] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Among the phospholipases A 2 (PLA 2s) are the group VI Ca (2+)-independent PLA 2s (iPLA 2s), and expression of multiple transcripts of iPLA 2 in skeletal muscle has been reported. In the present study, phospholipase activity and sequential ATP and calmodulin affinity column chromatography analyses reveal that skeletal muscle iPLA 2 exhibits properties characteristic of the iPLA 2beta isoform. The phospholipase activity of iPLA 2beta has been demonstrated to participate in signal transduction, cell proliferation, and apoptosis. We report here that skeletal muscle from iPLA 2beta-null mice, relative to wild-type muscle, exhibits a reduced capacity to oxidize palmitate but not palmitoyl-CoA or acetyl-CoA in the absence of changes in fatty acid transporters CD36 and CPT1 or beta-hydroxyacyl-CoA dehydrogenase activity. Recently, purified iPLA 2beta was demonstrated to manifest a thioesterase activity which catalyzes hydrolysis of fatty acyl-CoAs. The liberated CoA-SH facilitates fatty acid transport into the mitochondria. In this regard, we find that fractions eluted from the ATP column and containing iPLA 2beta phospholipase activity also contained acyl-CoA thioesterase activity that was inhibited by the bromoenol lactone (BEL) suicide inhibitor of iPLA 2beta. We further find that acyl-CoA thioesterase activity in skeletal muscle preparations from iPLA 2beta-null mice is significantly reduced, relative to WT activity. These findings suggest that the absence of acyl-CoA thioesterase activity of iPLA 2beta can lead to reduced fatty acyl-CoA generation and impair fatty acid oxidation in iPLA 2beta-null mice. Our findings therefore reveal a novel function of iPLA 2beta, related not to its phospholipase activity but to its thioesterase activity, which contributes to optimal fatty acid oxidation in skeletal muscle.
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Affiliation(s)
- Michael J Carper
- Mass Spectrometry Resource, Division of Metabolism, Endocrinology, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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44
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Abstract
The phospholipase A(2) (PLA(2)) superfamily consists of many different groups of enzymes that catalyze the hydrolysis of the sn-2 ester bond in a variety of different phospholipids. The products of this reaction, a free fatty acid, and lysophospholipid have many different important physiological roles. There are five main types of PLA(2): the secreted sPLA(2)'s, the cytosolic cPLA(2)'s, the Ca(2+)independent iPLA(2)'s, the PAF acetylhydrolases, and the lysosomal PLA(2)'s. This review focuses on the superfamily of PLA(2) enzymes, and then uses three specific examples of these enzymes to examine the differing biochemistry of the three main types of these enzymes. These three examples are the GIA cobra venom PLA(2), the GIVA cytosolic cPLA(2), and the GVIA Ca(2+)-independent iPLA(2).
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Affiliation(s)
- John E Burke
- Department of Chemistry and Biochemistry, School of Medicine, University of California, La Jolla, San Diego, CA 92093-0601, USA
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45
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Hooks SB, Cummings BS. Role of Ca2+-independent phospholipase A2 in cell growth and signaling. Biochem Pharmacol 2008; 76:1059-67. [PMID: 18775417 DOI: 10.1016/j.bcp.2008.07.044] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 07/15/2008] [Accepted: 07/15/2008] [Indexed: 01/25/2023]
Abstract
Phospholipase A(2) (PLA(2)) are esterases that cleave glycerophospholipids to release fatty acids and lysophospholipids. Several studies demonstrate that PLA(2) regulate growth and signaling in several cell types. However, few of these studies have focused on Ca2+-independent phospholipase A(2) (iPLA(2) or Group VI PLA(2)). This class of PLA(2) was originally suggested to mediate phospholipid remodeling in several cell types including macrophages. As such, it was labeled as a housekeeping protein and thought not to play as significant of roles in cell growth as its older counterparts cytosolic PLA(2) (cPLA(2) or Group IV PLA(2)) and secretory PLA(2) (sPLA(2) or Groups I-III, V and IX-XIV PLA(2)). However, several recent studies demonstrate that iPLA(2) mediate cell growth, and do so by participating in signal transduction pathways that include epidermal growth factor receptors (EGFR), mitogen activated protein kinases (MAPK), mdm2, and even the tumor suppressor protein p53 and the cell cycle regulator p21. The exact mechanism by which iPLA(2) mediates these pathways are not known, but likely involve the generation of lipid signals such as arachidonic acid, lysophosphatidic acid (LPA) and lysophosphocholines (LPC). This review discusses the role of iPLA(2) in cell growth with special emphasis placed on their role in cell signaling. The putative lipid signals involved are also discussed.
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Affiliation(s)
- Shelley B Hooks
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, USA
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46
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Líbano-Soares JD, Gomes-Quintana E, Melo HK, Queiroz-Madeira EP, Roubach RG, Lopes AG, Caruso-Neves C. B2 receptor-mediated dual effect of bradykinin on proximal tubule Na+ -ATPase: sequential activation of the phosphoinositide-specific phospholipase Cbeta/protein kinase C and Ca2+ -independent phospholipase A2 pathways. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1316-23. [PMID: 18291093 DOI: 10.1016/j.bbamem.2008.01.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/10/2008] [Accepted: 01/24/2008] [Indexed: 11/16/2022]
Abstract
In a previous paper we showed that bradykinin (BK), interacting with its B2 receptor, inhibits proximal tubule Na+ -ATPase activity but does not change (Na+ +K+)ATPase activity. The aim of this paper was to investigate the molecular mechanisms involved in B2-mediated modulation of proximal tubule Na+ -ATPase by BK. To abolish B1 receptor-mediated effects, all experiments were carried out in the presence of (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Leu), des-Arg9-[Leu8]-BK (DALBK), a specific antagonist of B1 receptor. A dual effect on the Na+ -ATPase activity through the B2 receptor was found: short incubation times (1-10 min) stimulate the enzyme activity; long incubation times (10-60 min) inhibit it. The stimulatory effect of BK is mediated by activation of phosphoinositide-specific phospholipase C beta (PI-PLCbeta)/protein kinase C (PKC); its inhibitory action is mediated by Ca2+ -independent phospholipase A2 (iPLA2). Prior activation of the PI-PLCbeta/PKC pathway is required to activate the iPLA2-mediated inhibitory phase. These results reveal a new mechanism by which BK can modulate renal sodium excretion: coupling between B2 receptor and activation of membrane-associated iPLA2.
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Affiliation(s)
- J D Líbano-Soares
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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47
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Bao S, Jacobson DA, Wohltmann M, Bohrer A, Jin W, Philipson LH, Turk J. Glucose homeostasis, insulin secretion, and islet phospholipids in mice that overexpress iPLA2beta in pancreatic beta-cells and in iPLA2beta-null mice. Am J Physiol Endocrinol Metab 2008; 294:E217-29. [PMID: 17895289 PMCID: PMC2268609 DOI: 10.1152/ajpendo.00474.2007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Studies with genetically modified insulinoma cells suggest that group VIA phospholipase A(2) (iPLA(2)beta) participates in amplifying glucose-induced insulin secretion. INS-1 insulinoma cells that overexpress iPLA(2)beta, for example, exhibit amplified insulin-secretory responses to glucose and cAMP-elevating agents. To determine whether similar effects occur in whole animals, we prepared transgenic (TG) mice in which the rat insulin 1 promoter (RIP) drives iPLA(2)beta overexpression, and two characterized TG mouse lines exhibit similar phenotypes. Their pancreatic islet iPLA(2)beta expression is increased severalfold, as reflected by quantitative PCR of iPLA(2)beta mRNA, immunoblotting of iPLA(2)beta protein, and iPLA(2)beta enzymatic activity. Immunofluorescence microscopic studies of pancreatic sections confirm iPLA(2)beta overexpression in RIP-iPLA(2)beta-TG islet beta-cells without obviously perturbed islet morphology. Male RIP-iPLA(2)beta-TG mice exhibit lower blood glucose and higher plasma insulin concentrations than wild-type (WT) mice when fasting and develop lower blood glucose levels in glucose tolerance tests, but WT and TG blood glucose levels do not differ in insulin tolerance tests. Islets from male RIP-iPLA(2)beta-TG mice exhibit greater amplification of glucose-induced insulin secretion by a cAMP-elevating agent than WT islets. In contrast, islets from male iPLA(2)beta-null mice exhibit blunted insulin secretion, and those mice have impaired glucose tolerance. Arachidonate incorporation into and the phospholipid composition of RIP-iPLA(2)beta-TG islets are normal, but they exhibit reduced Kv2.1 delayed rectifier current and prolonged glucose-induced action potentials and elevations of cytosolic Ca(2+) concentration that suggest a molecular mechanism for the physiological role of iPLA(2)beta to amplify insulin secretion.
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MESH Headings
- Animals
- Arachidonic Acid/metabolism
- Blood Glucose/metabolism
- Blood Glucose/physiology
- Blotting, Western
- Calcium/physiology
- Cell Line, Tumor
- DNA, Complementary/biosynthesis
- DNA, Complementary/genetics
- Fasting/metabolism
- Gene Expression Regulation, Enzymologic/physiology
- Genotype
- Glucose Tolerance Test
- Group IV Phospholipases A2/biosynthesis
- Group IV Phospholipases A2/genetics
- Homeodomain Proteins/genetics
- Homeostasis/physiology
- Insulin/blood
- Insulin/metabolism
- Insulin Secretion
- Insulin-Secreting Cells/metabolism
- Insulinoma/metabolism
- Islets of Langerhans/metabolism
- Kv1.2 Potassium Channel/metabolism
- Mice
- Mice, Knockout
- Mice, Transgenic
- Microscopy, Fluorescence
- Pancreatic Neoplasms/metabolism
- Patch-Clamp Techniques
- Phospholipids/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Spectrometry, Mass, Electrospray Ionization
- Trans-Activators/genetics
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Affiliation(s)
- Shunzhong Bao
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
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48
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Poitout V. Phospholipid hydrolysis and insulin secretion: a step toward solving the Rubik's cube. Am J Physiol Endocrinol Metab 2008; 294:E214-6. [PMID: 17925452 PMCID: PMC3167821 DOI: 10.1152/ajpendo.00638.2007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Vincent Poitout
- Montreal Diabetes Research Center, CR-CHUM, Technopole Angus, 2901 Rachel Est, Montreal, Quebec, Canada.
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49
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Cummings BS. Phospholipase A2 as targets for anti-cancer drugs. Biochem Pharmacol 2007; 74:949-59. [PMID: 17531957 DOI: 10.1016/j.bcp.2007.04.021] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 04/23/2007] [Accepted: 04/24/2007] [Indexed: 02/04/2023]
Abstract
Phospholipase A(2) (PLA(2)) are esterases that cleave glycerophospholipids to release fatty acids and lysophospholipids. Inhibition of PLA(2) alters cancer cell growth and death in vitro and PLA(2) expression is increased in breast, lung, and prostate cancers compared to control tissues. Thus, PLA(2) may be novel targets for chemotherapeutics. However, PLA(2) are a diverse family of enzymes, encompassing 19 members. The selectivity of these individual PLA(2) for phospholipids varies, as does their location within the cell, and tissue expression. Thus, their role in cancer may also vary. This review summarizes the expression of individual PLA(2) in cancers, focuses on the potential mechanisms by which these esterases mediate carcinogenesis, and suggests that select PLA(2) isoforms may be targets for anti-cancer drugs.
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Affiliation(s)
- Brian S Cummings
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602, USA.
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50
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Bao S, Li Y, Lei X, Wohltmann M, Jin W, Bohrer A, Semenkovich CF, Ramanadham S, Tabas I, Turk J. Attenuated free cholesterol loading-induced apoptosis but preserved phospholipid composition of peritoneal macrophages from mice that do not express group VIA phospholipase A2. J Biol Chem 2007; 282:27100-27114. [PMID: 17627946 PMCID: PMC2044506 DOI: 10.1074/jbc.m701316200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mouse macrophages undergo ER stress and apoptosis upon free cholesterol loading (FCL). We recently generated iPLA(2)beta-null mice, and here we demonstrate that iPLA(2)beta-null macrophages have reduced sensitivity to FCL-induced apoptosis, although they and wild-type (WT) cells exhibit similar increases in the transcriptional regulator CHOP. iPLA(2)beta-null macrophages are also less sensitive to apoptosis induced by the sarcoplasmic reticulum Ca(2+)-ATPase inhibitor thapsigargin and the scavenger receptor A ligand fucoidan, and restoring iPLA(2)betaexpression with recombinant adenovirus increases apoptosis toward WT levels. WT and iPLA(2)beta-null macrophages incorporate [(3)H]arachidonic acid ([(3)H]AA]) into glycerophosphocholine lipids equally rapidly and exhibit identical zymosan-induced, cPLA(2)alpha-catalyzed [(3)H]AA release. In contrast, although WT macrophages exhibit robust [(3)H]AA release upon FCL, this is attenuated in iPLA(2)beta-null macrophages and increases toward WT levels upon restoring iPLA(2)beta expression. Recent reports indicate that iPLA(2)beta modulates mitochondrial cytochrome c release, and we find that thapsigargin and fucoidan induce mitochondrial phospholipid loss and cytochrome c release into WT macrophage cytosol and that these events are blunted in iPLA(2)beta-null cells. Immunoblotting studies indicate that iPLA(2)beta associates with mitochondria in macrophages subjected to ER stress. AA incorporation into glycerophosphocholine lipids is unimpaired in iPLA(2)beta-null macrophages upon electrospray ionization-tandem mass spectrometry analyses, and their complex lipid composition is similar to WT cells. These findings suggest that iPLA(2)beta participates in ER stress-induced macrophage apoptosis caused by FCL or thapsigargin but that deletion of iPLA(2)beta does not impair macrophage arachidonate incorporation or phospholipid composition.
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Affiliation(s)
- Shunzhong Bao
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the
| | - Yankun Li
- Departments of Medicine and of Anatomy and Cell Biology, Columbia University, New York, New York 10032
| | - Xiaoyong Lei
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the
| | - Mary Wohltmann
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the
| | - Wu Jin
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the
| | - Alan Bohrer
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the
| | - Clay F Semenkovich
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the
| | - Sasanka Ramanadham
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the
| | - Ira Tabas
- Departments of Medicine and of Anatomy and Cell Biology, Columbia University, New York, New York 10032
| | - John Turk
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110 and the.
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