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Wang Y, Wakelam MJO, Bankaitis VA, McDermott MI. The wide world of non-mammalian phospholipase D enzymes. Adv Biol Regul 2024; 91:101000. [PMID: 38081756 DOI: 10.1016/j.jbior.2023.101000] [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: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 02/25/2024]
Abstract
Phospholipase D (PLD) hydrolyses phosphatidylcholine (PtdCho) to produce free choline and the critically important lipid signaling molecule phosphatidic acid (PtdOH). Since the initial discovery of PLD activities in plants and bacteria, PLDs have been identified in a diverse range of organisms spanning the taxa. While widespread interest in these proteins grew following the discovery of mammalian isoforms, research into the PLDs of non-mammalian organisms has revealed a fascinating array of functions ranging from roles in microbial pathogenesis, to the stress responses of plants and the developmental patterning of flies. Furthermore, studies in non-mammalian model systems have aided our understanding of the entire PLD superfamily, with translational relevance to human biology and health. Increasingly, the promise for utilization of non-mammalian PLDs in biotechnology is also being recognized, with widespread potential applications ranging from roles in lipid synthesis, to their exploitation for agricultural and pharmaceutical applications.
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Affiliation(s)
- Y Wang
- Department of Cell Biology & Genetics, Texas A&M Health Science Center, College Station, TX, 77843, USA; Department of Microbiology, University of Washington, Seattle, WA98109, USA
| | - M J O Wakelam
- Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, United Kingdom
| | - V A Bankaitis
- Department of Cell Biology & Genetics, Texas A&M Health Science Center, College Station, TX, 77843, USA; Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX, 77843, USA; Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - M I McDermott
- Department of Cell Biology & Genetics, Texas A&M Health Science Center, College Station, TX, 77843, USA.
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2
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Zhou C, Zhu X, Liu N, Dong X, Zhang X, Huang H, Tang Y, Liu S, Hu M, Wang M, Deng X, Li S, Zhang R, Huang Y, Lyu H, Xiao S, Luo S, Ali DW, Michalak M, Chen XZ, Wang Z, Tang J. B-lymphoid tyrosine kinase-mediated FAM83A phosphorylation elevates pancreatic tumorigenesis through interacting with β-catenin. Signal Transduct Target Ther 2023; 8:66. [PMID: 36797256 PMCID: PMC9935901 DOI: 10.1038/s41392-022-01268-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/13/2022] [Accepted: 11/13/2022] [Indexed: 02/18/2023] Open
Abstract
Abnormal activation of Wnt/β-catenin-mediated transcription is closely associated with the malignancy of pancreatic cancer. Family with sequence similarity 83 member A (FAM83A) was shown recently to have oncogenic effects in a variety of cancer types, but the biological roles and molecular mechanisms of FAM83A in pancreatic cancer need further investigation. Here, we newly discovered that FAM83A binds directly to β-catenin and inhibits the assembly of the cytoplasmic destruction complex thus inhibiting the subsequent phosphorylation and degradation. FAM83A is mainly phosphorylated by the SRC non-receptor kinase family member BLK (B-lymphoid tyrosine kinase) at tyrosine 138 residue within the DUF1669 domain that mediates the FAM83A-β-catenin interaction. Moreover, FAM83A tyrosine 138 phosphorylation enhances oncogenic Wnt/β-catenin-mediated transcription through promoting β-catenin-TCF4 interaction and showed an elevated nucleus translocation, which inhibits the recruitment of histone deacetylases by TCF4. We also showed that FAM83A is a direct downstream target of Wnt/β-catenin signaling and correlates with the levels of Wnt target genes in human clinical pancreatic cancer tissues. Notably, the inhibitory peptides that target the FAM83A-β-catenin interaction significantly suppressed pancreatic cancer growth and metastasis in vitro and in vivo. Our results revealed that blocking the FAM83A cascade signaling defines a therapeutic target in human pancreatic cancer.
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Affiliation(s)
- Cefan Zhou
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, T6G2R3, Canada
| | - Xiaoting Zhu
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Nanxi Liu
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, China
| | - Xueying Dong
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Xuewen Zhang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Huili Huang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
- Department of Systems Biology for Medicine, School of Basic Medical Sciences, Fudan University, and Shanghai Fifth People's Hospital, Fudan University, Shanghai, 200433, China
| | - Yu Tang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Shicheng Liu
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Mengyu Hu
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Ming Wang
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Xiaoling Deng
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Shi Li
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Rui Zhang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Yuan Huang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Hao Lyu
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Shuai Xiao
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China
| | - Sang Luo
- Ningxia Key Laboratory of Stem Cell and Regenerative Medicine, General Hospital of Ningxia Medical University, Ningxia, 750001, China
| | - Declan William Ali
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G2R3, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6G2R3, Canada
| | - Xing-Zhen Chen
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, T6G2R3, Canada
| | - Zhentian Wang
- Department of Systems Biology for Medicine, School of Basic Medical Sciences, Fudan University, and Shanghai Fifth People's Hospital, Fudan University, Shanghai, 200433, China.
| | - Jingfeng Tang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068, China.
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3
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Auclair N, Sané AT, Delvin E, Spahis S, Levy E. Phospholipase D as a Potential Modulator of Metabolic Syndrome: Impact of Functional Foods. Antioxid Redox Signal 2021; 34:252-278. [PMID: 32586106 DOI: 10.1089/ars.2020.8081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Significance: Cardiometabolic disorders (CMD) are composed of a plethora of metabolic dysfunctions such as dyslipidemia, nonalcoholic fatty liver disease, insulin resistance, and hypertension. The development of these disorders is highly linked to inflammation and oxidative stress (OxS), two metabolic states closely related to physiological and pathological conditions. Given the drastically rising CMD prevalence, the discovery of new therapeutic targets/novel nutritional approaches is of utmost importance. Recent Advances: The tremendous progress in methods/technologies and animal modeling has allowed the clarification of phospholipase D (PLD) critical roles in multiple cellular processes, whether directly or indirectly via phosphatidic acid, the lipid product mediating signaling functions. In view of its multiple features and implications in various diseases, PLD has emerged as a drug target. Critical Issues: Although insulin stimulates PLD activity and, in turn, PLD regulates insulin signaling, the impact of the two important PLD isoforms on the metabolic syndrome components remains vague. Therefore, after outlining PLD1/PLD2 characteristics and functions, their role in inflammation, OxS, and CMD has been analyzed and critically reported in the present exhaustive review. The influence of functional foods and nutrients in the regulation of PLD has also been examined. Future Directions: Available evidence supports the implication of PLD in CMD, but only few studies emphasize its mechanisms of action and specific regulation by nutraceutical compounds. Therefore, additional investigations are first needed to clarify the functional role of nutraceutics and, second, to elucidate whether targeting PLDs with food compounds represents an appropriate therapeutic strategy to treat CMD. Antioxid. Redox Signal. 34, 252-278.
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Affiliation(s)
- Nickolas Auclair
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada.,Department of Pharmacology & Physiology and Université de Montréal, Montreal, Quebec, Canada
| | - Alain T Sané
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Edgard Delvin
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Schohraya Spahis
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| | - Emile Levy
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada.,Department of Pharmacology & Physiology and Université de Montréal, Montreal, Quebec, Canada.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
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McDermott MI, Wang Y, Wakelam MJO, Bankaitis VA. Mammalian phospholipase D: Function, and therapeutics. Prog Lipid Res 2019; 78:101018. [PMID: 31830503 DOI: 10.1016/j.plipres.2019.101018] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/08/2019] [Accepted: 10/14/2019] [Indexed: 01/23/2023]
Abstract
Despite being discovered over 60 years ago, the precise role of phospholipase D (PLD) is still being elucidated. PLD enzymes catalyze the hydrolysis of the phosphodiester bond of glycerophospholipids producing phosphatidic acid and the free headgroup. PLD family members are found in organisms ranging from viruses, and bacteria to plants, and mammals. They display a range of substrate specificities, are regulated by a diverse range of molecules, and have been implicated in a broad range of cellular processes including receptor signaling, cytoskeletal regulation and membrane trafficking. Recent technological advances including: the development of PLD knockout mice, isoform-specific antibodies, and specific inhibitors are finally permitting a thorough analysis of the in vivo role of mammalian PLDs. These studies are facilitating increased recognition of PLD's role in disease states including cancers and Alzheimer's disease, offering potential as a target for therapeutic intervention.
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Affiliation(s)
- M I McDermott
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America.
| | - Y Wang
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, United States of America
| | - M J O Wakelam
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - V A Bankaitis
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, United States of America; Department of Chemistry, Texas A&M University, College Station, Texas 77840, United States of America
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5
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Arhab Y, Abousalham A, Noiriel A. Plant phospholipase D mining unravels new conserved residues important for catalytic activity. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:688-703. [DOI: 10.1016/j.bbalip.2019.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 01/09/2019] [Accepted: 01/13/2019] [Indexed: 01/16/2023]
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Schröck A, Henzi A, Bütikofer P, König S, Weinmann W. Determination of the formation rate of phosphatidylethanol by phospholipase D (PLD) in blood and test of two selective PLD inhibitors. Alcohol 2018; 73:1-7. [PMID: 30103144 DOI: 10.1016/j.alcohol.2018.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/08/2018] [Accepted: 03/13/2018] [Indexed: 11/29/2022]
Abstract
Phosphatidylethanol (PEth) is an alcohol biomarker formed from phosphatidylcholine (PC) by the enzyme phospholipase D (PLD) in the presence of ethanol. A drinking study revealed individual differences in maximum PEth levels after drinking to a targeted blood alcohol concentration (BAC) of 0.1%. This seemed to be due to different PLD activities in the tested persons. Furthermore, post-sampling formation of PEth occurred in blood samples, still containing alcohol. Therefore, a standardized in vitro test for measuring individual PEth formation rates was developed. Two PLD inhibitors were tested for their potency to inhibit post-sampling PEth formation. PEth-negative blood samples were collected from a volunteer. Ethanol was added in different concentrations (0.01-0.3% BAC) directly after blood sampling. The specimens were incubated at 37 °C. Aliquots were taken at the start of the incubation, and every hour until 8 h after start of incubation, and one sample was taken on subsequent days over 1 week. PEth 16:0/18:1 and PEth 16:0/18:2 were determined by online SPE-LC-MS/MS. Furthermore, this test system was applied to blood samples of 12 volunteers. For the inhibition tests, fresh blood (spiked with 0.1% ethanol) was spiked with 30, 300, 3000, or 30,000 nM of either halopemide or 5-fluoro-2-indolyl-deschlorohalopemide (FIPI), and incubated at 37 °C. PEth concentrations were determined hourly over 5 h on the first day and once on day 2 and day 3. PEth formation was linear in the first 7 h of incubation and dependent on the alcohol concentration. The formation rates of PEth 16:0/18:1 were 0.002 μmol L-1 h-1 (0.01% BAC), 0.016 μmol L-1 h-1 (0.1% BAC), 0.025 μmol L-1 h-1 (0.2% BAC), and 0.029 μmol L-1 h-1 (0.3% BAC). For PEth 16:0/18:2, the formation rates were 0.002 μmol L-1 h-1 (0.01% BAC), 0.019 μmol L-1 h-1 (0.1% BAC), 0.025 μmol L-1 h-1 (0.2% BAC), and 0.030 μmol L-1 h-1 (0.3% BAC). Maximum concentrations reached 431 ng/mL (PEth 16:0/18:1) and 496 ng/mL (PEth 16:0/18:2) at 0.3% BAC after 3 days. Maximum velocity (vmax) was not reached under these conditions. PEth formation in blood of the 12 volunteers ranged between 0.011 and 0.025 μmol L-1 h-1 for PEth 16:0/18:1 and between 0.014 and 0.021 μmol L-1 h-1 for PEth 16:0/18:2. PEth formation in human blood was inhibited by halopemide in a concentration-dependent manner. However, a complete inhibition was not achieved by the applied maximum concentration of 30,000 nM. FIPI showed a better inhibition of PEth formation. A complete inhibition could be achieved by a concentration of 30,000 nM for the first 24 h (for PEth 16:0/18:1) and for 48 h (for PEth 16:0/18:2). Formation of PEth was found to be dependent on the BAC. As a consequence, it is essential to inhibit PLD activity after blood collection to avoid post-sampling formation of PEth in blood samples with a positive BAC. Inhibition of PEth formation was more effective using FIPI, compared to halopemide.
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Affiliation(s)
- Alexandra Schröck
- Institute of Forensic Medicine, Forensic Toxicology and Chemistry, University of Bern, Bühlstrasse 20, 3012 Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, c/o Theodor Kocher Institute, Freiestrasse 1, 3012 Bern, Switzerland
| | - Anna Henzi
- Institute of Forensic Medicine, Forensic Toxicology and Chemistry, University of Bern, Bühlstrasse 20, 3012 Bern, Switzerland
| | - Peter Bütikofer
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland
| | - Stefan König
- Institute of Forensic Medicine, Forensic Toxicology and Chemistry, University of Bern, Bühlstrasse 20, 3012 Bern, Switzerland
| | - Wolfgang Weinmann
- Institute of Forensic Medicine, Forensic Toxicology and Chemistry, University of Bern, Bühlstrasse 20, 3012 Bern, Switzerland.
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Abstract
Phospholipases are lipolytic enzymes that hydrolyze phospholipid substrates at specific ester bonds. Phospholipases are widespread in nature and play very diverse roles from aggression in snake venom to signal transduction, lipid mediator production, and metabolite digestion in humans. Phospholipases vary considerably in structure, function, regulation, and mode of action. Tremendous advances in understanding the structure and function of phospholipases have occurred in the last decades. This introductory chapter is aimed at providing a general framework of the current understanding of phospholipases and a discussion of their mechanisms of action and emerging biological functions.
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Hyperactivation of EGFR and downstream effector phospholipase D1 by oncogenic FAM83B. Oncogene 2013; 33:3298-306. [PMID: 23912460 PMCID: PMC3923847 DOI: 10.1038/onc.2013.293] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 05/24/2013] [Accepted: 06/07/2013] [Indexed: 01/02/2023]
Abstract
Despite the progress made in targeted anticancer therapies in recent years, challenges remain. The identification of new potential targets will ensure that the arsenal of cancer therapies continues to expand. FAM83B was recently discovered in a forward genetic screen for novel oncogenes that drive human mammary epithelial cell (HMEC) transformation. We report here that elevated FAM83B expression increases Phospholipase D (PLD) activity, and that suppression of PLD1 activity prevents FAM83B-mediated transformation. The increased PLD activity is engaged by hyperactivation of epidermal growth factor receptor (EGFR), which is regulated by an interaction involving FAM83B and EGFR. Preventing the FAM83B/EGFR interaction by site-directed mutation of lysine 230 of FAM83B suppressed PLD activity and MAPK signaling. Furthermore, ablation of FAM83B expression from breast cancer cells inhibited EGFR phosphorylation and suppressed cell proliferation. We propose that understanding the mechanism of FAM83B-mediated transformation will provide a foundation for future therapies aimed at targeting its function as an intermediary in EGFR, MAPK, and mTOR activation.
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Phospholipase D as a catalyst: application in phospholipid synthesis, molecular structure and protein engineering. J Biosci Bioeng 2013; 116:271-80. [PMID: 23639419 DOI: 10.1016/j.jbiosc.2013.03.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/12/2013] [Accepted: 03/13/2013] [Indexed: 12/21/2022]
Abstract
Phospholipase D (PLD) is a useful enzyme for its transphosphatidylation activity, which enables the enzymatic synthesis of various phospholipids (PLs). Many reports exist on PLD-mediated synthesis of natural and tailor-made PLs with functional head groups, from easily available lecithin or phosphatidylcholine. Early studies on PLD-mediated synthesis mainly employed enzymes of plant origin, which were later supplanted by ones from microorganisms, especially actinomycetes. Many PLDs are members of the PLD superfamily, having one or two copies of a signature sequence, HxKxxxxD or HKD motif, in the primary structures. PLD superfamily members share a common core structure, and thereby, a common catalytic mechanism. The catalysis proceeds via two-step reaction with the formation of phosphatidyl-enzyme intermediate. Both of the two catalytic His residues are critical in the reaction course, where one acts as a nucleophile, while the other functions as a general acid/base. PLD is being engineered to improve its activity and stability, alter head group specificity and further identify catalytically important residues. Since the knowledge on PLD enzymology is constantly expanding, this review focuses on recent advances in the field, regarding PLD-catalyzed synthesis of bioactive PLs, deeper understanding of substrate recognition and binding mechanism, altering substrate specificity, and improving thermostability. We introduced some of our recent results in combination with existing facts to further deepen the story on the nature of this useful enzyme.
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Cipriano R, Graham J, Miskimen KLS, Bryson BL, Bruntz RC, Scott SA, Brown HA, Stark GR, Jackson MW. FAM83B mediates EGFR- and RAS-driven oncogenic transformation. J Clin Invest 2012; 122:3197-210. [PMID: 22886302 DOI: 10.1172/jci60517] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 05/16/2012] [Indexed: 11/17/2022] Open
Abstract
Aberrant regulation of growth signaling is a hallmark of cancer development that often occurs through the constitutive activation of growth factor receptors or their downstream effectors. Using validation-based insertional mutagenesis (VBIM), we identified family with sequence similarity 83, member B (FAM83B), based on its ability to substitute for RAS in the transformation of immortalized human mammary epithelial cells (HMECs). We found that FAM83B coprecipitated with a downstream effector of RAS, CRAF. Binding of FAM83B with CRAF disrupted CRAF/14-3-3 interactions and increased CRAF membrane localization, resulting in elevated MAPK and mammalian target of rapamycin (mTOR) signaling. Ablation of FAM83B inhibited the proliferation and malignant phenotype of tumor-derived cells or RAS-transformed HMECs, implicating FAM83B as a key intermediary in EGFR/RAS/MAPK signaling. Analysis of human tumor specimens revealed that FAM83B expression was significantly elevated in cancer and was associated with specific cancer subtypes, increased tumor grade, and decreased overall survival. Cumulatively, these results suggest that FAM83B is an oncogene and potentially represents a new target for therapeutic intervention.
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Affiliation(s)
- Rocky Cipriano
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, USA
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11
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Jang YH, Min DS. Intermolecular association between caspase-mediated cleavage fragments of phospholipase D1 protects against apoptosis. Int J Biochem Cell Biol 2011; 44:358-65. [PMID: 22108201 DOI: 10.1016/j.biocel.2011.11.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 10/24/2011] [Accepted: 11/07/2011] [Indexed: 11/17/2022]
Abstract
Phospholipase D plays an anti-apoptotic role but little is known about dynamics of phospholipase D turnover during apoptosis. We have recently identified phospholipase D1 as a new substrate of caspases which generates the N-terminal and C-terminal fragment of phospholipase D1. In the present study, we tried to investigate whether association of the caspase cleavage fragments may be involved in regulation of apoptosis. Ectopically expressed C-terminal fragment, but not N-terminal fragment of phospholipase D1, is exclusively imported into the nucleus via a nuclear localization sequence; however, endogenous C-terminal fragment of phospholipase D1 from etoposide-induced apoptotic cells and Alzheimer's disease brain tissues with active caspase-3, was localized in the cytosolic fraction as well as the nuclear fraction. Intermolecular association between the two fragments of phospholipase D1 through hydrophobic residues within the catalytic motif inhibited nuclear localization of C-terminal fragment of phospholipase D1, and two catalytic motif and nuclear localization sequence regulated nuclocytoplasmic shuttling of phospholipase D1. Moreover, hydrophobic residues involved in the intermolecular association are also required for both its enzymatic activity and anti-apoptotic function. Taken together, we demonstrate that interdomain association and dissociation of phospholipase D1 might provide new insights into modulation of apoptosis.
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Affiliation(s)
- Young Hoon Jang
- Department of Molecular Biology, College of Natural Science, Pusan National University, Busan, 609-735, Republic of Korea
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12
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Selvy PE, Lavieri RR, Lindsley CW, Brown HA. Phospholipase D: enzymology, functionality, and chemical modulation. Chem Rev 2011; 111:6064-119. [PMID: 21936578 PMCID: PMC3233269 DOI: 10.1021/cr200296t] [Citation(s) in RCA: 269] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Paige E Selvy
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37064, USA
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Scognamiglio PL, Doti N, Grieco P, Pedone C, Ruvo M, Marasco D. Discovery of Small Peptide Antagonists of PED/PEA15-D4α Interaction from Simplified Combinatorial Libraries. Chem Biol Drug Des 2011; 77:319-27. [DOI: 10.1111/j.1747-0285.2011.01094.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Giusto NM, Pasquaré SJ, Salvador GA, Ilincheta de Boschero MG. Lipid second messengers and related enzymes in vertebrate rod outer segments. J Lipid Res 2009; 51:685-700. [PMID: 19828910 DOI: 10.1194/jlr.r001891] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rod outer segments (ROSs) are specialized light-sensitive organelles in vertebrate photoreceptor cells. Lipids in ROS are of considerable importance, not only in providing an adequate environment for efficient phototransduction, but also in originating the second messengers involved in signal transduction. ROSs have the ability to adapt the sensitivity and speed of their responses to ever-changing conditions of ambient illumination. A major contributor to this adaptation is the light-driven translocation of key signaling proteins into and out of ROS. The present review shows how generation of the second lipid messengers from phosphatidylcholine, phosphatidic acid, and diacylglycerol is modulated by the different illumination states in the vertebrate retina. Findings suggest that the light-induced translocation of phototransduction proteins influences the enzymatic activities of phospholipase D, lipid phosphate phosphatase, diacylglyceride lipase, and diacylglyceride kinase, all of which are responsible for the generation of the second messenger molecules.
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Affiliation(s)
- Norma M Giusto
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.
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15
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Uesugi Y, Hatanaka T. Phospholipase D mechanism using Streptomyces PLD. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:962-9. [PMID: 19416643 DOI: 10.1016/j.bbalip.2009.01.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 01/19/2009] [Accepted: 01/28/2009] [Indexed: 11/17/2022]
Abstract
Phospholipase D (PLD) plays various roles in important biological processes and physiological functions, including cell signaling. Streptomyces PLDs show significant sequence similarity and belong to the PLD superfamily containing two catalytic HKD motifs. These PLDs have conserved catalytic regions and are among the smallest PLD enzymes. Therefore, Streptomyces PLDs are thought to be suitable models for studying the reaction mechanism among PLDs from other sources. Furthermore, Streptomyces PLDs present advantages related to their broad substrate specificity and ease of enzyme preparation. Moreover, the tertiary structure of PLD has been elucidated only for PLD from Streptomyces sp. PMF. This article presents a review of recently reported studies of the mechanism of the catalytic reaction, substrate recognition, substrate specificity and stability of Streptomyces PLD using various protein engineering methods and surface plasmon resonance analysis.
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Affiliation(s)
- Yoshiko Uesugi
- Research Institute for Biological Sciences (RIBS), Kaga-gun, Okayama, Japan
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16
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Design of isoform-selective phospholipase D inhibitors that modulate cancer cell invasiveness. Nat Chem Biol 2009; 5:108-17. [PMID: 19136975 DOI: 10.1038/nchembio.140] [Citation(s) in RCA: 237] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 12/15/2008] [Indexed: 12/29/2022]
Abstract
Phospholipase D (PLD) is an essential enzyme responsible for the production of the lipid second messenger phosphatidic acid. Phosphatidic acid participates in both G protein-coupled receptor and receptor tyrosine kinase signal transduction networks. The lack of potent and isoform-selective inhibitors has limited progress in defining the cellular roles of PLD. We used a diversity-oriented synthetic approach and developed a library of PLD inhibitors with considerable pharmacological characterization. Here we report the rigorous evaluation of that library, which contains highly potent inhibitors, including the first isoform-selective PLD inhibitors. Specific members of this series inhibit isoforms with >100-fold selectivity both in vitro and in cells. A subset of inhibitors was shown to block invasiveness in metastatic breast cancer models. These findings demonstrate the power of diversity-oriented synthesis combined with biochemical assays and mass spectrometric lipid profiling of cellular responses to develop the first isoform-selective PLD inhibitors--a new class of antimetastatic agents.
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Caspase cleavage of phospholipase D1 in vitro alters its regulation and reveals a novel property of the "loop" region. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1781:376-82. [PMID: 18573349 DOI: 10.1016/j.bbalip.2008.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 05/19/2008] [Accepted: 05/26/2008] [Indexed: 11/20/2022]
Abstract
Phospholipase D (PLD) has been implicated in mediating vesicular transport, mitosis, differentiation and apoptosis. The product of PLD activity, phosphatidic acid (PA) has mitogenic potential and elevated PLD expression has been detected in many tumor cell lines. Several reports have demonstrated that distinct PLD domains regulate its activity and that truncated forms of PLD retain enzymatic activity. We hypothesized that during apoptosis caspase cleavage of PLDs could result in modification of their activities. To test this idea, we have used in vitro translation of PLD1 and PLD2 which generated active enzymes exhibiting properties mimicking those of the endogenous proteins. Here we demonstrate that PLD1 was rapidly cleaved in vitro by caspases-8, -3 and -7. In contrast, PLD2 cleavage was delayed and its activity was unaffected by incubation with caspase-3. Significantly, following caspase cleavage the response of PLD1 to regulatory stimuli was altered; it was no longer activated by PKC and instead exhibited an increased activity in response to small GTPases. Notably, this enhanced activity was due to cleavage of PLD1 in the "loop" domain, a region previously associated with negative regulatory function. Thus our data have identified a novel regulatory domain in PLD1.
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18
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Expression and purification of the D4 region of PLD1 and characterization of its interaction with PED-PEA15. Protein Expr Purif 2008; 59:302-8. [DOI: 10.1016/j.pep.2008.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 02/22/2008] [Accepted: 02/22/2008] [Indexed: 11/20/2022]
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Wright MH, Farquhar MJ, Aletrari MO, Ladds G, Hodgkin MN. Identification of caspase 3 motifs and critical aspartate residues in human phospholipase D1b and phospholipase D2a. Biochem Biophys Res Commun 2008; 369:478-84. [PMID: 18298948 DOI: 10.1016/j.bbrc.2008.02.064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 02/09/2008] [Indexed: 11/24/2022]
Abstract
Stimulation of mammalian cells frequently initiates phospholipase D-catalyzed hydrolysis of phosphatidylcholine in the plasma membrane to yield phosphatidic acid (PA) a novel lipid messenger. PA plays a regulatory role in important cellular processes such as secretion, cellular shape change, and movement. A number of studies have highlighted that PLD-based signaling also plays a pro-mitogenic and pro-survival role in cells and therefore anti-apoptotic. We show that human PLD1b and PLD2a contain functional caspase 3 cleavage sites and identify the critical aspartate residues within PLD1b that affect its activation by phorbol esters and attenuate phosphatidylcholine hydrolysis during apoptosis.
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Affiliation(s)
- Michelle H Wright
- Department of Biological Sciences, University of Warwick, Coventry West Midlands CV4 7AL, UK
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20
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Exton JH. In Search of the Message. J Biol Chem 2008; 283:14901-9. [DOI: 10.1074/jbc.x800001200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Abstract
Recently, we identified Ala426 and Lys438 of phospholipase D from Streptomyces septatus TH-2 (TH-2PLD) as important residues for activity, stability and selectivity in transphosphatidylation. These residues are located in a C-terminal flexible loop separate from two catalytic HxKxxxxD motifs. To study the role of these residues in substrate recognition, we evaluated the affinities of inactive mutants, in which these residues were substituted with Phe and His, toward several phospholipids by SPR analysis. By substituting Ala426 and Lys438 with Phe and His, respectively, the inactive mutant showed a much stronger interaction with phosphatidylcholine and a weaker interaction with phosphatidylglycerol than the inactive TH-2PLD mutant. We demonstrated that Ala426 and Lys438 of TH-2PLD play a role in sensing the head group of phospholipids.
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Affiliation(s)
- Yoshiko Uesugi
- Research Institute for Biological Sciences (RIBS), Okayama, Japan
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Yamada Y, Banno Y, Yoshida H, Kikuchi R, Akao Y, Murate T, Nozawa Y. Catalytic inactivation of human phospholipase D2 by a naturally occurring Gly901Asp mutation. Arch Med Res 2006; 37:696-9. [PMID: 16824927 DOI: 10.1016/j.arcmed.2006.01.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Accepted: 01/04/2006] [Indexed: 11/20/2022]
Abstract
BACKGROUND We previously showed that the 1814C-->T (Thr577Ile) polymorphism of the human phospholipase D2 (PLD2) gene is associated with the prevalence of colorectal cancer, with the T allele representing a risk factor for this condition. However, we failed to detect a difference in PLD activity of cell lysates or membrane fractions between cells transfected with cDNAs encoding the Thr577 or Ile577 variants of PLD2. In the present study, we have examined the possible functional relevance of other naturally occurring polymorphisms (or mutations) of the human PLD2 gene that result in amino acid substitutions. METHODS Human embryonic kidney cells were transfected with expression vectors for each PLD2 variant and assayed for enzyme activity in vitro and in vivo. RESULTS AND CONCLUSIONS The G-->A (Gly901Asp) mutation of the human PLD2 gene was found to result in catalytic inactivation of the encoded protein.
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Affiliation(s)
- Yoshiji Yamada
- Department of Human Functional Genomics, Life Science Research Center, Mie University, Tsu, Japan.
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Kook S, Exton JH. Identification of interaction sites of protein kinase Cα on phospholipase D1. Cell Signal 2005; 17:1423-32. [PMID: 15951158 DOI: 10.1016/j.cellsig.2005.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Revised: 02/22/2005] [Accepted: 03/03/2005] [Indexed: 11/29/2022]
Abstract
Phospholipase D (PLD) is regulated by many factors, including protein kinase C (PKC) and small G-proteins of the Rho and ADP-ribosylation factor families. Previous studies revealed that the activation of PLD1 by phorbol ester is associated with the binding of PKCalpha to a site in the N-terminus of PLD1. The purpose of the present study was to determine this site more precisely. Immunoprecipitation with a series of four PLD1 deletion mutants confirmed that PKCalpha strongly interacted with the amino acid sequence 1-318 at the N-terminus of PLD1 and weakly with the sequence 841-1036 at the C-terminus. Further immunoprecipitation studies with deletion mutants of the 1-318 and 1-215 PLD1 fragments revealed that there were binding sites in the 1-49 N-terminal sequence and also in the 216-318 sequence containing the PH domain. Studies of N-terminal deletion mutants of full-length PLD1 confirmed the presence of a binding site in the 1-49 sequence and a further site in the 1-318 sequence. Both deletion mutants showed impaired activation by PKCalpha in vivo, but unchanged activation by active V(14)RhoA. These findings identify the 1-49 sequence is a major binding/activation site for PKCalpha on PLD1, but also indicate involvement of the PH domain.
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Affiliation(s)
- Seunghyi Kook
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Ho WT, Xie Z, Zhao ZJ, Exton JH. Tyrosine phosphorylation of phospholipase D1 by v-Src does not per se result in activation. Cell Signal 2005; 17:691-9. [PMID: 15722193 DOI: 10.1016/j.cellsig.2004.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Accepted: 10/11/2004] [Indexed: 10/26/2022]
Abstract
The relationship between tyrosine phosphorylation and activation of phospholipase D1 (PLD1) by v-Src was examined. Co-expression of v-Src and PLD1 in COS-7 cells resulted in increased activity and marked tyrosine phosphorylation of PLD1. PLD activity was increased in membranes or immunoprecipitates prepared from these cells. Dephosphorylation of the immunoprecipitated enzyme by tyrosine phosphatase or phosphorylation by c-Src produced no changes in its activity. Tyrosine phosphorylation induced by v-Src caused a shift of the enzyme from the Triton-soluble to the Triton-insoluble fraction. v-Src and PLD1 could be co-immunoprecipitated from cells co-expressing these and were co-localized in the perinuclear region as assessed by immunofluorescence. Mutation of the palmitoylation sites of PLD1 significantly reduced tyrosine phosphorylation by v-Src. It is concluded that tyrosine phosphorylation of PLD1 by v-Src does not per se alter its activity. It is proposed that activation of PLD1 by v-Src in vivo may involve association/colocalization of the two proteins.
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Affiliation(s)
- Wan-Ting Ho
- Howard Hughes Medical Institute and the Department of Molecular Physiology and Biophysics, Room 831 Light Hall, Vanderbilt University School of Medicine, Nashville, TN 37232, United States
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Negishi T, Mukaihara T, Mori K, Nishikido H, Kawasaki Y, Aoki H, Kodama M, Uedaira H, Uesugi Y, Iwabuchi M, Hatanaka T. Identification of a key amino acid residue of Streptomyces phospholipase D for thermostability by in vivo DNA shuffling. Biochim Biophys Acta Gen Subj 2005; 1722:331-42. [PMID: 15777623 DOI: 10.1016/j.bbagen.2005.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Revised: 12/20/2004] [Accepted: 01/04/2005] [Indexed: 11/20/2022]
Abstract
To isolate thermostability-related amino acid residues of Streptomyces phospholipase D (PLD), we constructed a chimeral genes library between two highly homologous plds, which exhibited different thermostabilities, by an in vivo DNA shuffling method using Escherichia coli that has a mutation of a single-stranded DNA-binding protein gene. To confirm the location of the recombination site, we carried out the restriction mapping of 68 chimeral pld genes. The recombination sites were widely dispersed over the entire pld sequence. Moreover, we examined six chimeral PLDs by comparing their thermostabilities with those of parental PLDs. To identify a thermostability-related amino acid residue, we investigated the thermostability of chimera C that was the most thermolabile among the six chimeras. We identified the thermostability-related factor Gly-188, which is located in the alpha-7 helix of PLD from Streptomyces septatus TH-2 (TH-2PLD). TH-2PLD mutants, in which Gly-188 was substituted with Phe, Val or Trp, exhibited higher thermostabilities than that of the parental PLD. Gly-188 substituted with the Phe mutant, which was the most stable among the mutants, showed an enzyme activity almost the same as that of TH-2PLD as determine by kinetic analysis.
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Affiliation(s)
- Tomofumi Negishi
- Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Kibichuo-cho, Kaga-gun, Okayama 716-1241, Japan
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Zambonelli C, Roberts MF. Non-HKD Phospholipase D Enzymes: New Players in Phosphatidic Acid Signaling? ACTA ACUST UNITED AC 2005; 79:133-81. [PMID: 16096028 DOI: 10.1016/s0079-6603(04)79003-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- Carlo Zambonelli
- Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA
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Zambonelli C, Casali M, Roberts MF. Mutagenesis of Putative Catalytic and Regulatory Residues of Streptomyces chromofuscus Phospholipase D Differentially Modifies Phosphatase and Phosphodiesterase Activities. J Biol Chem 2003; 278:52282-9. [PMID: 14557260 DOI: 10.1074/jbc.m310252200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phospholipase D from Streptomyces chromofuscus (sc-PLD) is a member of the diverse family of metallo-phosphodiesterase/phosphatase enzymes that also includes purple acid phosphatases, protein phosphatases, and nucleotide phosphodiesterases. Whereas iron is an essential cofactor for scPLD activity, Mn2+ is also found in the enzyme. A third metal ion, Ca2+, has been shown to enhance scPLD catalytic activity although it is not an essential cofactor. Sequence alignment of scPLD with known phosphodiesterases and phosphatases requiring metal ions suggested that His-212, Glu-213, and Asp-389 could be involved in Mn2+ binding. H212A, E213A, and D389A were prepared to test this hypothesis. These three mutant enzymes and wild type scPLD show similar metal content but considerably different catalytic properties, suggesting different roles for each residue. His-212 appears involved in binding the phosphate group of substrates, whereas Glu-213 acts as a ligand for Ca2+. D389A showed a greatly reduced phosphodiesterase activity but almost unaltered ability to hydrolyze the phosphate group in p-nitrophenyl phosphate suggesting it had a critical role in aligning groups at the active site to control phosphodiesterase versus phosphatase activities. We propose a model for substrate and cofactor binding to the catalytic site of scPLD based on these results and on sequence alignment to purple acid phosphatases of known structure.
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Affiliation(s)
- Carlo Zambonelli
- Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA
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Zambonelli C, Roberts MF. An iron-dependent bacterial phospholipase D reminiscent of purple acid phosphatases. J Biol Chem 2003; 278:13706-11. [PMID: 12519726 DOI: 10.1074/jbc.m210363200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recombinant phospholipase D (PLD) from Streptomyces chromofuscus (scPLD) has been characterized using colorimetric assays, spectroscopic investigations, and site-directed mutagenesis. scPLD, which shows phosphodiesterase activity toward a wide variety of phospholipids and phosphatase activity toward p-nitrophenyl phosphate, exhibits a visible absorption band with lambda(max) at 570 nm. Metal ion analysis performed by inductively coupled plasma mass spectroscopy shows the presence of approximately 1 equivalent of iron, 0.27 equivalent of manganese, and 0.1 equivalent of zinc per mole of protein as isolated. The metal ion content coupled with the visible absorption feature is compatible with the presence of Fe(3+)-tyrosinate coordination. When scPLD was dialyzed against solutions containing Mn(2+), Zn(2+) or EDTA, the Fe(3+) content was reduced to variable extents, and the residual specific activity correlated well with the residual iron content. Sequence homology with metal ion binding motifs in known alkaline phosphatases and purple acid phosphatase from red kidney bean shows that most of the residues involved in metal ion coordination are conserved among all the sequences considered. Mutation of some of these conserved residues (C123A, D151A, Y154F, and H391A) produced enzymes lacking iron with dramatically reduced PLD activity but little change in secondary structure or ability to bind to small unilamellar vesicles of phosphatidylcholine (with Ba(2+)) or phosphatidic acid. We suggest that scPLD is a member of a family of phosphodiesterase/phosphatases with structural and mechanistic similarity to iron-dependent purple acid phosphatases.
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Affiliation(s)
- Carlo Zambonelli
- Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA
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Mammalian phospholipase D – properties and regulation. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1569-2558(03)33022-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
Structural studies of plant and bacterial members of the phospholipase D (PLD) superfamily are providing information about the role of the conserved HKD domains in the structure of the catalytic center and the catalytic mechanism of mammalian PLD isozymes (PLD1 and PLD2). Mutagenesis and sequence comparison studies have also defined the presence of pleckstrin homology and phox homology domains in the N-terminus and have demonstrated that a conserved sequence at the C-terminus is required for catalysis. The N- and C-terminal regions of PLD1 also contain interaction sites for protein kinase C, which can directly activate the enzyme through a non-phosphorylating mechanism. Small G proteins of the Rho and ADP-ribosylation factor families also directly regulate the enzyme, with RhoA binding to a sequence in the C-terminus. Certain tyrosine kinases and members of the Ras subfamily of small G proteins can activate the enzyme, but the mechanisms appear to be indirect. The mechanisms by which agonists activate PLD in vivo probably involve multiple pathways.
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Affiliation(s)
- John H Exton
- Howard Hughes Medical Institute and Vanderbilt University Medical Center, Nashville, TN 38232-0295, USA.
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Affiliation(s)
- J H Exton
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
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32
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Affiliation(s)
- Zhi Xie
- Department of Molecular Physiology and Biophysics, Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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33
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Xie Z, Ho WT, Spellman R, Cai S, Exton JH. Mechanisms of regulation of phospholipase D1 and D2 by the heterotrimeric G proteins G13 and Gq. J Biol Chem 2002; 277:11979-86. [PMID: 11812783 DOI: 10.1074/jbc.m109751200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Our earlier studies of rat brain phospholipase D1 (rPLD1) showed that the enzyme could be activated in cells by alpha subunits of the heterotrimeric G proteins G(13) and G(q). Recently, we showed that rPLD1 is modified by Ser/Thr phosphorylation and palmitoylation. In this study, we first investigated the roles of these post-translational modifications on the activation of rPLD1 by constitutively active Galpha(13)Q226L and Galpha(q)Q209L. Mutations of Cys(240) and Cys(241) of rPLD1, which abolish both post-translational modifications, did not affect the ability of either Galpha(13)Q226L or Galpha(q)Q209L to activate rPLD1. However, the RhoA-insensitive mutants, rPLD1(K946A,K962A) and rPLD1(K962Q), were not activated by Galpha(13)Q226L, although these mutant enzymes responded to phorbol ester and Galpha(q)Q209L. On the contrary, the PKC-insensitive mutant rPLD1(DeltaN168), which lacks the first 168 amino acids of rPLD1, responded to Galpha(13)Q226L but not to Galpha(q)Q209L. In addition, we found that rPLD2 was strongly activated by Galpha(q)Q209L and phorbol ester. However, surprisingly, the enzymatic activity of rPLD2 was suppressed by Galpha(13)Q226L and constitutively active V14RhoA in COS-7 cells. Abolition of the post-translational modifications of rPLD2 did not alter the effects of Galpha(q)Q209L or Galpha(13)Q226L. The suppressive effect of Galpha(13)Q226L on rPLD2 was reversed by dominant negative N19RhoA and the C3 exoenzyme of Clostridium botulinum, further supporting a role for RhoA. In summary, Galpha(13) activation of rPLD1 in COS-7 cells is mediated by Rho, while Galpha(q) activation requires PKC. rPLD2 is activated by Galpha(q), but is inhibited by Galpha(13). Neither Ser/Thr phosphorylation nor palmitoylation is required for these effects.
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Affiliation(s)
- Zhi Xie
- Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0295, USA
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Rizzo M, Romero G. Pharmacological importance of phospholipase D and phosphatidic acid in the regulation of the mitogen-activated protein kinase cascade. Pharmacol Ther 2002; 94:35-50. [PMID: 12191592 DOI: 10.1016/s0163-7258(02)00170-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The stimulation of cells with many extracellular agonists leads to the activation of phospholipase (PL)D. PLD metabolizes phosphatidylcholine to generate phosphatidic acid (PA). Neither the mechanism through which cell surface receptors regulate PLD activation nor the functional consequences of PLD activity in mitogenic signaling are completely understood. PLD is activated by protein kinase C, phospholipids, and small GTPases of the ADP-ribosylation factor and Rho families, but the mechanisms linking cell surface receptors to the activation of PLD still require detailed analysis. Furthermore, the latest data on the functional consequences of the generation of cellular PA suggest an important role for this lipid in the regulation of membrane traffic and on the activation of the mitogen-activated protein kinase cascade. This review addresses these issues, examining some novel models for the physiological role of PLD and PA and discussing their potential usefulness as specific targets for the development of new therapies.
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Affiliation(s)
- Mark Rizzo
- Department of Pharmacology, W 1345 BSTWR, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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Lee S, Kim JH, Lee CS, Kim JH, Kim Y, Heo K, Ihara Y, Goshima Y, Suh PG, Ryu SH. Collapsin response mediator protein-2 inhibits neuronal phospholipase D(2) activity by direct interaction. J Biol Chem 2002; 277:6542-9. [PMID: 11741937 DOI: 10.1074/jbc.m108047200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the functional significance of neuronal phospholipase D (PLD) is being recognized, little is known about its regulatory role in neuronal cells. To elucidate the regulatory mechanism of neuronal PLD, we investigated PLD(2)-binding neuronal protein from rat brain cytosol. During the fractionation of rat brain cytosol by four-column chromatography, a 62-kDa PLD(2)-interacting protein was detected by PLD(2) overlay assay and identified as collapsin response mediator protein-2 (CRMP-2), which controls neuronal axon guidance and outgrowth. Using bacterially expressed glutathione S-transferase fusion proteins, we found that two regions (amino acids 65-192 (the phagocytic oxidase domain) and 724-825) of PLD(2) and a single region (amino acids 243-300) of CRMP-2 are required for the direct binding of both proteins. A co-immunoprecipitation study in COS-7 cells also showed an in vivo interaction between CRMP-2 and PLD(2). Interestingly, CRMP-2 was found to potently inhibit PLD(2) activity in a concentration-dependent manner (IC(50) = 30 nm). Overexpression studies also showed that CRMP-2 is an in vivo inhibitor of PLD(2) in PC12 cells. Moreover, increasing the concentration of semaphorin 3A, one of the repulsive axon guidance cues, showed that PLD(2) activity can be inhibited in PC12 cells. Immunocytochemistry further revealed that PLD(2) is co-localized with CRMP-2 in the distal tips of neurites, its possible action site, in differentiated PC12 cells. Taken together, our results indicate that CRMP-2 may interact directly with and inhibit neuronal PLD(2), suggesting that this inhibitory mode of regulation may play a role in neuronal pathfinding during the developmental stage.
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Affiliation(s)
- Sukmook Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
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Dunkirk SG, Wallert MA, Baumgartner ML, Provost JJ. Isolation and characterization of a 66-kDa protein from rat liver plasma membrane with RhoA-stimulated phospholipase D activity. Protein Expr Purif 2002; 24:1-12. [PMID: 11812216 DOI: 10.1006/prep.2001.1541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A 66-kDa molecular weight protein with phospholipase D activity was solubilized and partially purified from rat liver plasma membrane. The activity and regulation of this phospholipase D have been characterized. Immunoblot analyses indicated that the enzyme was distinct from hPLD1 and PLD2, but was recognized by an antibody to the 12 terminal amino acids of PLD1. PLD activity was stimulated by 1-100 microM Ca(2+) and Mg(2+) and displayed a pH optimum of 7.5. Activity was inhibited by both saturated and unsaturated fatty acids. This PLD was activated in an ATP-independent manner by the PKC isozymes alpha and betaII but not activated by other PKC isozymes. It was also stimulated by the small G-proteins RhoA and ARF. RhoA stimulated the greatest activation, followed by ARF and PKC(alpha). This enzyme was further activated in a synergistic manner when combinations of PKC(alpha) and RhoA or ARF were used. This enzyme displayed a greater response activation by RhoA than to activation by ARF. While a potential breakdown product of PLD1, activation by RhoA indicates that the PLD characterized here is distinct from the other PLDs cloned or isolated to date.
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Affiliation(s)
- Shawn G Dunkirk
- Department of Chemistry and Department of Biology, Minnesota State University Moorhead, Moorhead, Minnesota 56563, USA
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Xie Z, Ho WT, Exton JH. Functional implications of post-translational modifications of phospholipases D1 and D2. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1580:9-21. [PMID: 11923096 DOI: 10.1016/s1388-1981(01)00168-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Our previous studies showed that truncation of the N-terminal 168 amino acids of rat brain phospholipase D1 (rPLD1) abolishes its response to protein kinase C (PKC) and greatly diminishes its palmitoylation and Ser/Thr phosphorylation. In this study, we show that the response to PKC as well as the palmitoylation and Ser/Thr phosphorylation were restored when the truncated rPLD1 mutant (rPLD1(DeltaN168)) was coexpressed with a fragment containing the N-terminal 168 amino acids. Immunoprecipitation experiments showed that the N-terminal fragment associated with rPLD1(DeltaN168) when coexpressed in COS 7 cells and that palmitoylation of Cys(240) and Cys(241) was not necessary for the association. In addition, we found that rat PLD2 (rPLD2) was palmitoylated on Cys(223) and Cys(224) in COS 7 cells. Mutation of both these cysteines reduced the basal activity of rPLD2, however its response to PMA stimulation in vivo was retained. As in the case of rPLD1, loss of palmitoylation weakened membrane association of rPLD2. In summary, the N-terminal 168-amino-acid fragment of rPLD1 can associate with truncated rPLD1(DeltaN168) to restore its palmitoylation, Ser/Thr phosphorylation and PKC response. Although rPLD2 differs from rPLD1 in many properties, it is palmitoylated at the corresponding conserved cysteine residues in COS 7 cells.
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Affiliation(s)
- Zhi Xie
- Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0295, USA
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38
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Kam Y, Exton JH. Phospholipase D activity is required for actin stress fiber formation in fibroblasts. Mol Cell Biol 2001; 21:4055-66. [PMID: 11359912 PMCID: PMC87067 DOI: 10.1128/mcb.21.12.4055-4066.2001] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phospholipase D (PLD) is a ubiquitously expressed enzyme of ill-defined function. In order to explore its cellular actions, we inactivated the rat PLD1 (rPLD1) isozyme by tagging its C terminus with a V5 epitope (rPLD1-V5). This was stably expressed in Rat-2 fibroblasts to see if it acted as a dominant-negative mutant for PLD activity. Three clones that expressed rPLD1-V5 were selected (Rat2V16, Rat2V25, and Rat2V29). Another clone (Rat2V20) that lost expression of rPLD1-V5 was also obtained. In the three clones expressing rPLD1-V5, PLD activity stimulated by phorbol myristate acetate (PMA) or lysophosphatidic acid (LPA) was reduced by ~50%, while the PLD activity of Rat2V20 cells was normal. Changes in the actin cytoskeleton in response to LPA or PMA were examined in these clones. All three clones expressing rPLD1-V5 failed to form actin stress fibers after treatment with LPA. However, Rat2V20 cells formed stress fibers in response to LPA to the same extent as wild-type Rat-2 cells. In contrast, there was no significant change in membrane ruffling induced by PMA in the cells expressing rPLD1-V5. Since Rho is an activator both of rPLD1 and stress fiber formation, the activation of Rho was monitored in wild-type Rat-2 cells and Rat2V25 cells, but no significant difference was detected. The phosphorylation of vimentin mediated by Rho-kinase was also intact in Rat2V25 cells. Rat2V25 cells also showed normal vinculin-containing focal adhesions. However, the translocation of alpha-actinin to the cytoplasm and to the detergent-insoluble fraction in Rat2V25 cells was reduced. These results indicate that PLD activity is required for LPA-induced rearrangement of the actin cytoskeleton to form stress fibers and that PLD might be involved in the cross-linking of actin filaments mediated by alpha-actinin.
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Affiliation(s)
- Y Kam
- Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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39
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Hughes WE, Parker PJ. Endosomal localization of phospholipase D 1a and 1b is defined by the C-termini of the proteins, and is independent of activity. Biochem J 2001; 356:727-36. [PMID: 11389680 PMCID: PMC1221899 DOI: 10.1042/0264-6021:3560727] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The factors regulating the activity of cellular phospholipase D (PLD) have been well characterized; however, the cellular distribution of specific PLD isoforms and the factors defining localization are less clear. Two specific PLD1 isoforms, PLD1a and PLD1b, are shown in the present study to be localized in endosomal compartments with early endosomal autoantigen 1, internalizing epidermal growth factor receptor (ErbB1) and lysobisphosphatidic acid. Novel C-terminal splice variants of PLD1, PLD1a2 and PLD1b2, do not exhibit this endosomal localization. Studies using catalytically inactive and C-terminal deletion mutants of the four PLD1 isoforms led to the conclusion that the C-terminus plays an important part in the catalytic activity of PLD1, but that the endosomal localization of PLD1a and PLD1b is defined by the C-terminus and not catalytic activity.
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Affiliation(s)
- W E Hughes
- Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, 44, Lincoln's Inn Fields, London WC2A 3PX, UK
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40
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Abstract
Phospholipase D (PLD) is regulated by many factors, including protein kinase C (PKC) and small G-proteins of the Rho and ADP-ribosylation factor families. Previous studies revealed that the interaction site of human PLD(1) for RhoA is located in its C-terminus, but the exact locus has not been determined. The purpose of the present study was to determine the interaction site of rat PLD(1) (rPLD(1)) with RhoA. Selection with phage display of different peptides of rPLD(1) confirmed that GTP-bound RhoA interacted with a site in the amino acid sequence 873-1024 at the C-terminus of rPLD(1). RhoA also associated with this peptide in a GTP-dependent manner in COS-7 cell lysates and the peptide inhibited RhoA stimulation of PLD activity in membranes from COS-7 cells expressing rPLD(1). A series of alanine mutations of non-conserved residues were made in this sequence, and the enzymes were expressed in COS-7 cells and checked for responses to activation of PKC, which interacts with the N-terminus of PLD(1), and also to the constitutively active V14RhoA. Mutations in the C-terminus of rPLD(1) (K946A, V950A, R955A and K962A) caused partial loss of V14RhoA stimulation, and double mutations (K946A/K962A, K946A/V950A and K962A/V950A) caused an almost total loss. Co-immunoprecipitation studies also showed that the mutated forms of rPLD(1) described above failed to bind V14RhoA compared with wild-type rPLD(1), whereas rPLD(1) with mutations outside the region K946-K962 bound V14RhoA normally. It is concluded that basic amino acids in a restricted C-terminal region of rPLD(1) are important for binding of RhoA and its activation of PLD activity.
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Affiliation(s)
- S Cai
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0295, USA
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41
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Kirsch C, Wetzker R, Klinger R. Anionic phospholipids are involved in membrane targeting of PI 3-kinase gamma. Biochem Biophys Res Commun 2001; 282:691-6. [PMID: 11401516 DOI: 10.1006/bbrc.2001.4623] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phosphoinositide 3-kinases (PI 3-kinases) have critical roles in diverse cellular signaling processes and in protein trafficking. In contrast to the class I PI 3-kinases alpha, beta, and delta which bind via src homology 2 (SH2) domains of adaptor proteins to tyrosine kinase receptors, the mechanism of recruitment of the PI 3-kinase gamma to membranes is unknown. We report in vitro experiments using immobilized proteins and small unilamellar vesicles which suggest an involvement of anionic phospholipids in membrane association of PI 3-kinase gamma. Furthermore we provide evidence that the enzyme displays beside the catalytic center a phospholipid binding domain which is essential for enzyme activity.
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Affiliation(s)
- C Kirsch
- Institute of Biochemistry II, Medical Faculty, University of Jena, Nonnenplan 2, Jena, D-07740, Germany
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42
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Abstract
Rat brain phospholipase D1 (rPLD1) has two highly conserved motifs (HXKX(4)D), denoted HKD, located in the N- and C-terminal halves, which are required for phospholipase D activity. The two halves of rPLD1 can associate in vivo, and the association is essential for catalytic activity and Ser/Thr phosphorylation of the enzyme. In this study, we found that this association is also required for palmitoylation of rPLD1, which occurs on cysteines 240 and 241. In addition, palmitoylation of rPLD1 requires the N-terminal sequence but not the conserved C-terminal sequence, since rPLD1 that lacks the first 168 amino acids is not palmitoylated in vivo, while the inactive C-terminal deletion mutant is. Palmitoylation of rPLD1 is not necessary for catalytic activity, since N-terminal truncation mutants lacking the first 168 or 319 amino acids exhibit high basal activity although they cannot be stimulated by protein kinase C (PKC). The lack of response to PKC is not due to the lack of palmitoylation, since mutation of both Cys(240) and Cys(241) to alanine in full-length rPLD1 abolishes palmitoylation, but the mutant still retains basal activity and responds to PKC. Palmitoylation-deficient rPLD1 can associate with crude membranes; however, the association is weakened. Wild type rPLD1 remains membrane-associated when extracted with 1 m NaCl or Na(2)CO(3) (pH 11), while rPLD1 mutants that lack palmitoylation are partially released. In addition, we found that palmitoylation-deficient mutants are much less modified by Ser/Thr phosphorylation compared with wild type rPLD1. Characterization of the other cysteine mutations of rPLD1 showed that mutation of cysteine 310 or 612 to alanine increased basal phospholipase D activity 2- and 4-fold, respectively. In summary, palmitoylation of rPLD1 requires interdomain association and the presence of the N-terminal 168 amino acids. Mutations of cysteines 240 and 241 to alanine abolish the extensive Ser/Thr phosphorylation of the enzyme and weaken its association with membranes.
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Affiliation(s)
- Z Xie
- Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0295, USA
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43
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Liu MY, Gutowski S, Sternweis PC. The C terminus of mammalian phospholipase D is required for catalytic activity. J Biol Chem 2001; 276:5556-62. [PMID: 11083860 DOI: 10.1074/jbc.m006404200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of phospholipase D (PLD) is regulated by a variety of hormonal stimuli and provides a mechanistic pathway for response of cells to extracellular stimuli. The two identified mammalian PLD enzymes possess highly homologous C termini, which are required for catalytic activity. Mutational analysis of PLD1 and PLD2 reveals that modification of as little as the C-terminal threonine or the addition of a single alanine attenuates activity of the enzyme. Protein folding appears to be intact because mutant enzymes express to similar levels in Sf9 cells and addition of peptides representing the C-terminal amino acids, including the simple hexamer PMEVWT, restores partial activity to several of the mutants. Analysis of several mutants suggests a requirement for the hydrophobic reside at the -2-position but not an absolute requirement for the hydroxyl side chain of threonine at the C terminus. The inability of peptides amidated at their C termini to effect restoration of activity indicates the involvement of the C-terminal alpha carboxyl group in functional activity of these enzymes. The ability of peptides to restore activity to PLD enzymes mutated at the C terminus suggests a flexible interaction of this portion of the molecule with a catalytic core constructed on conserved HKD motifs. Participation of these C termini residues in either stabilization of the catalytic site or the enzymatic reaction itself remains to be determined. This requirement for the C terminus provides an excellent potential site for interaction with regulatory proteins that may either enhance or down-regulate the activity of these enzymes in vitro.
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Affiliation(s)
- M Y Liu
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9041, USA
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44
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Xie Z, Ho WT, Exton JH. Conserved amino acids at the C-terminus of rat phospholipase D1 are essential for enzymatic activity. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:7138-46. [PMID: 11106425 DOI: 10.1046/j.1432-1327.2000.01816.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Rat brain phospholipase D1 (rPLD1) has two highly conserved motifs [H(X)K(X)4D, denoted HKD] located at the N-terminal and C-terminal halves, which are required for activity. Association of the two halves is essential for rPLD1 activity, which probably brings the two HKD domains together to form a catalytic center. In the present study, we find that an intact C-terminus is also essential for the catalytic activity of rPLD1. Serial deletion of the last four amino acids, EVWT, which are conserved in all mammalian PLD isoforms, abolished the catalytic activity of rPLD1. This loss of catalytic activity was not due to a lack of association of the N-terminal and C-terminal halves. Mutations of the last three amino acids showed that substitutions with charged or less hydrophobic amino acids all reduced PLD activity. For example, mutations of Thr1036 and Val1034 to Asp or Lys caused marked inactivation, whereas mutation to other amino acids had less effect. Mutation of Trp1035 to Leu, Ala, His or Tyr caused complete inactivation, whereas mutation of Glu1033 to Ala enhanced activity. The size of the amino acids at the C-terminus also affected the catalytic activity of PLD, reduced activity being observed with conservative mutations within the EVWT sequence (such as T/S, V/L or W/F). The enzyme was also inactivated by the addition of Ala or Val to the C-terminus of this sequence. Interestingly, the inactive C-terminal mutants could be complemented by cotransfection with a wild-type C-terminal half to restore PLD activity in vivo. These data demonstrate that the integrity of the C-terminus of rPLD1 is essential for its catalytic activity. Important features are the hydrophobicity, charge and size of the four conserved C-terminal amino acids. It is proposed that these play important roles in maintaining a functional catalytic structure by interacting with a specific domain within rPLD1.
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Affiliation(s)
- Z Xie
- Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0295, USA
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45
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Devlin MA, Das S, Singh I, Bourgoin S, Brindley DN, Ginsberg J. The characterization of phospholipase D in FRTL-5 thyroid cells. Mol Cell Endocrinol 2000; 167:107-15. [PMID: 11000525 DOI: 10.1016/s0303-7207(00)00299-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We previously demonstrated that TSH activates phospholipase D (PLD) in Fischer rat thyroid line (FRTL)-5 cells. To date, two types of mammalian phosphatidylcholine-specific PLD cDNAs, designated as PLD-1 and PLD-2, have been cloned. The present study determined the PLD isoform composition in FRTL-5 thyroid cells and which isoform is regulated by TSH. PLD-1 is activated by small molecular weight G-proteins, such as ADP-ribosylation factor (ARF) and RhoA family members, while PLD-2 is relatively independent of such stimuli. We established the presence of PLD-1 and PLD-2 by Western blot analysis and compared PLD activity in cytosol, membranes and combined fractions in the presence and absence of GTPgammaS. The membrane fraction showed very little activity in the absence of GTPgammaS, but this activity increased approximately 5-fold (P<0.05, ANOVA) in the presence of GTPgammaS. Maximal PLD activity was seen with the combination of membrane plus cytosolic fractions (which contained ARF and RhoA) where the addition of GTPgammaS increased PLD activity approximately 8-fold (P<0.05, ANOVA). To determine the relative activities of PLD-1 and PLD-2 in FRTL-5 thyroid cells, cell-free PLD assays were performed in the presence of GTPgammaS or GDPbetaS with varying concentrations of phosphatidylinositol 4,5-bisphosphate (PIP(2)). PLD-2 contributed only approximately 19% of the total amount of PLD activity in the membranes and PLD-1 was the predominant PLD isoform. TSH stimulated PLD-1 activity by up to 2. 3-fold over control values (P<0.01, ANOVA). To establish the dependence of PLD-1 on small molecular weight G-proteins, the translocations of ARF and RhoA to the membrane fractions was determined after stimulation by TSH. Both ARF and RhoA were maximally translocated to the membrane fraction after 10 min incubation with 100 microU/ml TSH by approximately 1.7- and 2.3-fold over control values, respectively (P<0.02 and P<0.03, ANOVA). It is concluded that TSH stimulates PLD-1 activity in FRTL-5 thyroid cells and this is accompanied by the translocation of ARF and RhoA to the membrane fraction.
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Affiliation(s)
- M A Devlin
- Department of Medicine, Signal Transduction Laboratories, University of Alberta, Alta, T6G2S2, Edmonton, Canada
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46
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Höer A, Cetindag C, Oberdisse E. Influence of phosphatidylinositol 4,5-bisphosphate on human phospholipase D1 wild-type and deletion mutants: is there evidence for an interaction of phosphatidylinositol 4,5-bisphosphate with the putative pleckstrin homology domain? BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1481:189-201. [PMID: 10962106 DOI: 10.1016/s0167-4838(00)00108-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP(2)) is an essential cofactor of phospholipase D (PLD) enzymes. In order to further characterize its role in PLD activation, we have constructed N-terminal deletion mutants of the human PLD1 (hPLD1) and a mutant lacking the putative pleckstrin homology domain (delta PH), which has been proposed to be involved in PIP(2) binding. For the N-terminal deletion mutants (up to 303 amino acids) and the delta PH mutant we found no significant differences compared to the hPLD1 wild-type, except changes in the specific activities: the K(m) values were about 20 microM for the substrate phosphatidylcholine, and PIP(2) activated the PLD enzymes maximally between 5 and 10 microM. In contrast, preincubation of the PLD proteins with 5-10 microM PIP(2) or PIP(2)-containing lipid vesicles inhibited the PLD activity. This inhibition was neither abolished by n-octyl-beta-D-glucopyranoside or neomycin nor by the ADP-ribosylation factor, another activator of PLD enzymes. All tested PLD proteins were active without PIP(2) in the presence of 1 M ammonium sulfate. The 303 N-terminal amino acids of hPLD1 are not involved in substrate binding or the interaction with PIP(2). Our data indicate further that the putative PH domain of hPLD1 is not responsible for the essential effects of PIP(2) on PLD activity.
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Affiliation(s)
- A Höer
- Institut für Pharmakologie, Fachbereich Humanmedizin der Freien Universität Berlin, Thielallee 67-73, 14195 Berlin, Germany.
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47
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Xie Z, Ho WT, Exton JH. Association of the N- and C-terminal domains of phospholipase D. Contribution of the conserved HKD motifs to the interaction and the requirement of the association for Ser/Thr phosphorylation of the enzyme. J Biol Chem 2000; 275:24962-9. [PMID: 10825182 DOI: 10.1074/jbc.m909745199] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rat brain phospholipase D1 (rPLD1) belongs to a superfamily defined by the highly conserved catalytic motif (H(X)K(X)(4)D, denoted HKD. rPLD1 contains two HKD domains, located in the N- and C-terminal regions. The integrity of the two HKD domains is essential for enzymatic activity. Our previous studies showed that the N-terminal half of rPLD1 containing one HKD motif can associate with the C-terminal half containing the other HKD domain to reconstruct wild type PLD activity (Xie, Z., Ho, W.-T. and Exton, J. H. (1998) J. Biol. Chem. 273, 34679-34682). In the present study, we have shown by mutagenesis that conserved amino acids in the HKD domains are important for both the catalytic activity and the association between the two halves of rPLD1. Furthermore, we found that rPLD1 could be modified by Ser/Thr phosphorylation. The modification occurred at the N-terminal half of the enzyme, however, the association of the N-terminal domain with the C-terminal domain was required for the modification. The phosphorylation of the enzyme was not required for its catalytic activity or response to PKCalpha and small G proteins in vitro, although the phosphorylated form of rPLD1 was localized exclusively in the crude membrane fraction. In addition, we found that the individually expressed N- and C-terminal fragments did not interact when mixed in vitro and were unable to reconstruct PLD activity under these conditions. It is concluded that the association of the N- and C-terminal halves of rPLD1 requires their co-expression in vivo and depends on conserved residues in the HKD domains. The association is also required for Ser/Thr phosphorylation of the enzyme.
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Affiliation(s)
- Z Xie
- Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0295, USA
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48
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Park JB, Kim JH, Kim Y, Ha SH, Yoo JS, Du G, Frohman MA, Suh PG, Ryu SH. Cardiac phospholipase D2 localizes to sarcolemmal membranes and is inhibited by alpha-actinin in an ADP-ribosylation factor-reversible manner. J Biol Chem 2000; 275:21295-301. [PMID: 10801846 DOI: 10.1074/jbc.m002463200] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myocardial phospholipase D (PLD) has been implicated in the regulation of Ca(2+) mobilization and contractile performance in the heart. However, the molecular identity of this myocardial PLD and the mechanisms that regulate it are not well understood. Using subcellular fractionation and Western blot analysis, we found that PLD2 is the major myocardial PLD and that it localizes primarily to sarcolemmal membranes. A 100-kDa PLD2-interacting cardiac protein was detected using a protein overlay assay employing purified PLD2 and then identified as alpha-actinin using peptide-mass fingerprinting with matrix-assisted laser desorption/ionization mass spectroscopy. The direct association between PLD2 and alpha-actinin was confirmed using an in vitro binding assay and localized to PLD2's N-terminal 185 amino acids. Purified alpha-actinin potently inhibits PLD2 activity (IC(50) = 80 nm) in an interaction-dependent and ADP-ribosylation factor-reversible manner. Finally, alpha-actinin co-localizes with actin and with PLD2 in the detergent-insoluble fraction from sarcolemmal membranes. These results suggest that PLD2 is reciprocally regulated in sarcolemmal membranes by alpha-actinin and ARF1 and accordingly that a major role for PLD2 in cardiac function may involve reorganization of the actin cytoskeleton.
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Affiliation(s)
- J B Park
- Department of Life Science, Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
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49
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Abstract
Phospholipase D is an ubiquitous enzyme that hydrolyzes phosphatidylcholine to phosphatidic acid and choline. Its cellular actions are related to the production of phosphatidic acid and include alterations to cell growth, shape, and secretion. There are two mammalian phospholipase D genes whose products (PLD1 and PLD2) are alternatively spliced. Both forms have two highly conserved HKD motifs that are essential for catalysis and dimerization. PLD1 is regulated in vitro and in vivo by protein kinase C and small GTPases of the Rho and ARF families, whereas PLD2 shows a higher basal activity with little or no response to these proteins. The cellular locations and specific functions of the two PLD isoforms remain to be established.
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Affiliation(s)
- J H Exton
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0295, USA.
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50
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Freeman EJ. The Ang II-induced growth of vascular smooth muscle cells involves a phospholipase D-mediated signaling mechanism. Arch Biochem Biophys 2000; 374:363-70. [PMID: 10666319 DOI: 10.1006/abbi.1999.1608] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Angiotensin (Ang) II acts as a mitogen in vascular smooth muscle cells (VSMC) via the activation of multiple signaling cascades, including phospholipase C, tyrosine kinase, and mitogen-activated protein kinase pathways. However, increasing evidence supports signal-activated phospholipases A(2) and D (PLD) as additional mechanisms. Stimulation of PLD results in phosphatidic acid (PA) formation, and PA has been linked to cell growth. However, the direct involvement of PA or its metabolite diacylglycerol (DAG) in Ang II-induced growth is unclear. PLD activity was measured in cultured rat VSMC prelabeled with [(3)H]oleic acid, while the incorporation of [(3)H]thymidine was used to monitor growth. We have previously reported the Ang II-dependent, AT(1)-coupled stimulation of PLD and growth in VSMC. Here, we show that Ang II (100 nM) and exogenous PLD (0.1-100 units/mL; Streptomyces chromofuscus) stimulated thymidine incorporation (43-208% above control). PA (100 nM-1 microM) also increased thymidine incorporation to 135% of control. Propranolol (100 nM-10 microM), which inhibits PA phosphohydrolase, blocked the growth stimulated by Ang II, PLD, or PA by as much as 95%, an effect not shared by other beta-adrenergic antagonists. Propranolol also increased the production of PA in the presence of Ang II by 320% and reduced DAG and arachidonic acid (AA) accumulation. The DAG lipase inhibitor RHC-80267 (1-10 microM) increased Ang II-induced DAG production, while attenuating thymidine incorporation and release of AA. Thus, it appears that activation of PLD, formation of PA, conversion of PA to DAG, and metabolism of DAG comprise an important signaling cascade in Ang II-induced growth of VSMC.
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Affiliation(s)
- E J Freeman
- Department of Internal Medicine, Calhoun Research Laboratory, Akron, Ohio 44307, USA
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