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Aktories K, Gierschik P, Heringdorf DMZ, Schmidt M, Schultz G, Wieland T. cAMP guided his way: a life for G protein-mediated signal transduction and molecular pharmacology-tribute to Karl H. Jakobs. Naunyn Schmiedebergs Arch Pharmacol 2019; 392:887-911. [PMID: 31101932 DOI: 10.1007/s00210-019-01650-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 04/02/2019] [Indexed: 12/14/2022]
Abstract
Karl H. Jakobs, former editor-in-chief of Naunyn-Schmiedeberg's Archives of Pharmacology and renowned molecular pharmacologist, passed away in April 2018. In this article, his scientific achievements regarding G protein-mediated signal transduction and regulation of canonical pathways are summarized. Particularly, the discovery of inhibitory G proteins for adenylyl cyclase, methods for the analysis of receptor-G protein interactions, GTP supply by nucleoside diphosphate kinases, mechanisms in phospholipase C and phospholipase D activity regulation, as well as the development of the concept of sphingosine-1-phosphate as extra- and intracellular messenger will presented. His seminal scientific and methodological contributions are put in a general and timely perspective to display and honor his outstanding input to the current knowledge in molecular pharmacology.
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Affiliation(s)
- Klaus Aktories
- Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Albert Ludwigs University, 79104, Freiburg, Germany
| | - Peter Gierschik
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89070, Ulm, Germany
| | - Dagmar Meyer Zu Heringdorf
- Institute of General Pharmacology and Toxicology, University Hospital Frankfurt am Main, Goethe University, 60590, Frankfurt am Main, Germany
| | - Martina Schmidt
- Department of Molecular Pharmacology, University of Groningen, 9713AV, Groningen, The Netherlands
| | - Günter Schultz
- Department of Pharmacology, Charité University Medical Center Berlin, Campus Benjamin Franklin, 14195, Berlin, Germany
| | - Thomas Wieland
- Experimental Pharmacology Mannheim (EPM), European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Str. 13 - 17, 68167, Mannheim, Germany.
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2
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Bernfeld E, Menon D, Vaghela V, Zerin I, Faruque P, Frias MA, Foster DA. Phospholipase D-dependent mTOR complex 1 (mTORC1) activation by glutamine. J Biol Chem 2018; 293:16390-16401. [PMID: 30194281 DOI: 10.1074/jbc.ra118.004972] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 08/31/2018] [Indexed: 01/06/2023] Open
Abstract
Glutamine is a key nutrient required for sustaining cell proliferation, contributing to nucleotide, protein, and lipid synthesis. The mTOR complex 1 (mTORC1) is a highly conserved protein complex that acts as a sensor of nutrients, relaying signals for the shift from catabolic to anabolic metabolism. Although glutamine plays an important role in mTORC1 activation, the mechanism is not clear. Here we describe a leucine- and Rag-independent mechanism of mTORC1 activation by glutamine that depends on phospholipase D and the production of phosphatidic acid, which is required for the stability and activity of mTORC1. The phospholipase D-dependent activation of mTORC1 by glutamine depended on the GTPases ADP ribosylation factor 1 (Arf1), RalA, and Rheb. Glutamine deprivation could be rescued by α-ketoglutarate, a downstream metabolite of glutamine. This mechanism represents a distinct nutrient input to mTORC1 that is independent of Rag GTPases and leucine.
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Affiliation(s)
- Elyssa Bernfeld
- From the Departments of Biological Sciences and.,the Biochemistry Program and
| | - Deepak Menon
- From the Departments of Biological Sciences and.,the Biochemistry Program and
| | - Vishaldeep Vaghela
- From the Departments of Biological Sciences and.,Biology Program, Graduate Center, City University of New York, New York, New York 10016, and
| | - Ismat Zerin
- Chemistry, Hunter College, City University of New York, New York, New York 10065
| | | | | | - David A Foster
- From the Departments of Biological Sciences and .,the Biochemistry Program and.,Biology Program, Graduate Center, City University of New York, New York, New York 10016, and.,the Department of Pharmacology, Weill Cornell Medicine, New York, New York 10021
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3
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Bruntz RC, Lindsley CW, Brown HA. Phospholipase D signaling pathways and phosphatidic acid as therapeutic targets in cancer. Pharmacol Rev 2015; 66:1033-79. [PMID: 25244928 DOI: 10.1124/pr.114.009217] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phospholipase D is a ubiquitous class of enzymes that generates phosphatidic acid as an intracellular signaling species. The phospholipase D superfamily plays a central role in a variety of functions in prokaryotes, viruses, yeast, fungi, plants, and eukaryotic species. In mammalian cells, the pathways modulating catalytic activity involve a variety of cellular signaling components, including G protein-coupled receptors, receptor tyrosine kinases, polyphosphatidylinositol lipids, Ras/Rho/ADP-ribosylation factor GTPases, and conventional isoforms of protein kinase C, among others. Recent findings have shown that phosphatidic acid generated by phospholipase D plays roles in numerous essential cellular functions, such as vesicular trafficking, exocytosis, autophagy, regulation of cellular metabolism, and tumorigenesis. Many of these cellular events are modulated by the actions of phosphatidic acid, and identification of two targets (mammalian target of rapamycin and Akt kinase) has especially highlighted a role for phospholipase D in the regulation of cellular metabolism. Phospholipase D is a regulator of intercellular signaling and metabolic pathways, particularly in cells that are under stress conditions. This review provides a comprehensive overview of the regulation of phospholipase D activity and its modulation of cellular signaling pathways and functions.
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Affiliation(s)
- Ronald C Bruntz
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
| | - Craig W Lindsley
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
| | - H Alex Brown
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
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Scotland RL, Allen L, Hennings LJ, Post GR, Post SR. The ral exchange factor rgl2 promotes cardiomyocyte survival and inhibits cardiac fibrosis. PLoS One 2013; 8:e73599. [PMID: 24069211 PMCID: PMC3775766 DOI: 10.1371/journal.pone.0073599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 07/25/2013] [Indexed: 12/24/2022] Open
Abstract
Cardiomyocytes compensate to acute cardiac stress by increasing in size and contractile function. However, prolonged stress leads to a decompensated response characterized by cardiomyocyte death, tissue fibrosis and loss of cardiac function. Identifying approaches to inhibit this transition to a decompensated response may reveal important targets for treating heart failure. The Ral guanine nucleotide disassociation (RalGDS) proteins are Ras-interacting proteins that are upregulated by hypertrophic stimuli. The Ral guanine nucleotide dissociation stimulator-like 2 (Rgl2) is a member of the RalGDS family that modulates expression of hypertrophic genes in cardiomyocytes. However, the pathophysiologic consequence of increased Rgl2 expression in cardiomyoctyes remains unclear. To evaluate the effect of increasing Rgl2 activity in the heart, transgenic mice with cardiac-targeted over-expression of Rgl2 were generated. Although Ral activation was increased, there were no apparent morphologic or histological differences between the hearts of Rgl2 transgenic and nontransgenic mice indicating that increased Rgl2 expression had no effect on basal cardiac phenotype. To determine if Rgl2 modulates the cardiac response to stress, mice were infused with the ß-adrenergic receptor agonist, isoproterenol. Isoproterenol infusion increased heart mass in both Rgl2 transgenic and nontransgenic mice. However, unlike nontransgenic mice, Rgl2 transgenic mice showed no morphologic evidence of cardiomyocyte damage or increased cardiac fibrosis following isoproterenol infusion. Increased Rgl2 expression in cultured cardiomyocytes stimulated Ral activation and inhibited staurosporine-induced apoptosis via increased activation of PI3-kinase. Activation of the PI3-kinase signaling pathway was confirmed in hearts isolated from Rgl2 transgenic mice. Increased expression and function of Rgl2 in cardiomyocytes promotes activation of the PI3-kinase signaling cascade and protects from carciomyocyte death and pathologic cardiac fibrosis. Taken further, these results suggest that Rgl2 upregulation in hypertrophic hearts may be a protetive mechanism, and that Rgl2 may be a novel therapeutic target in treating heart disease.
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Affiliation(s)
- Rebecca L. Scotland
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Leah Allen
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky, United States of America
| | - Leah J. Hennings
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Ginell R. Post
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky, United States of America
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Steven R. Post
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky, United States of America
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky, United States of America
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail:
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Rifki OF, Bodemann BO, Battiprolu PK, White MA, Hill JA. RalGDS-dependent cardiomyocyte autophagy is required for load-induced ventricular hypertrophy. J Mol Cell Cardiol 2013; 59:128-38. [PMID: 23473774 DOI: 10.1016/j.yjmcc.2013.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 02/09/2013] [Accepted: 02/26/2013] [Indexed: 01/19/2023]
Abstract
Recent work has demonstrated that autophagy, a phylogenetically conserved, lysosome-mediated pathway of protein degradation, is a key participant in pathological cardiac remodeling. One common feature of cell growth and autophagy is membrane biogenesis and processing. The exocyst, an octomeric protein complex involved in vesicle trafficking, is implicated in numerous cellular processes, yet its role in cardiomyocyte plasticity is unknown. Here, we set out to explore the role of small G protein-dependent control of exocyst function and membrane trafficking in stress-induced cardiomyocyte remodeling and autophagy. First, we tested in cultured neonatal rat cardiomyocytes (NRCMs) two isoforms of Ral (RalA, RalB) whose actions are mediated by the exocyst. In these experiments, mTOR inhibition in response to starvation or Torin1 was preserved despite RalA or RalB knockdown; however, activation of autophagy was suppressed only in NRCMs depleted of RalB, implicating RalB as being required for mTOR-dependent cardiomyocyte autophagy. To define further the role of RalB in cardiomyocyte autophagy, we analyzed hearts from mice lacking RalGDS (Ralgds(-/-)), a guanine exchange factor (GEF) for the Ral family of small GTPases. RalGDS-null hearts were similar to wild-type (WT) littermates in terms of ventricular structure, contractile performance, and gene expression. However, Ralgds(-/-) hearts manifested a blunted growth response (p<0.05) to TAC-mediated pressure-overload stress. Ventricular chamber size and contractile performance were preserved in response to TAC in Ralgds(-/-) mice, and load-induced cardiomyocyte autophagy was suppressed. Interestingly, TAC-induced activation of the fetal gene program was similar in both genotypes despite the relative lack of hypertrophic growth in mutant hearts. Together, these data implicate RalGDS-mediated induction of autophagy and exocyst function as a critical feature of load-induced cardiac hypertrophy.
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Affiliation(s)
- Oktay F Rifki
- Department of Internal Medicine, Cardiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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Yoon MS, Du G, Backer JM, Frohman MA, Chen J. Class III PI-3-kinase activates phospholipase D in an amino acid-sensing mTORC1 pathway. ACTA ACUST UNITED AC 2011; 195:435-47. [PMID: 22024166 PMCID: PMC3206351 DOI: 10.1083/jcb.201107033] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In response to amino acid availability, the class III PI-3-kinase hVps34 activates the phospholipase PLD and mTORC1 signaling to regulate mammalian cell size. The rapamycin-sensitive mammalian target of rapamycin (mTOR) complex, mTORC1, regulates cell growth in response to mitogenic signals and amino acid availability. Phospholipase D (PLD) and its product, phosphatidic acid, have been established as mediators of mitogenic activation of mTORC1. In this study, we identify a novel role for PLD1 in an amino acid–sensing pathway. We find that amino acids activate PLD1 and that PLD1 is indispensable for amino acid activation of mTORC1. Activation of PLD1 by amino acids requires the class III phosphatidylinositol 3-kinase hVps34, which stimulates PLD1 activity through a functional interaction between phosphatidylinositol 3-phosphate and the Phox homology (PX) domain of PLD1. Furthermore, amino acids stimulate PLD1 translocation to the lysosomal region where mTORC1 activation occurs in an hVps34-dependent manner, and this translocation is necessary for mTORC1 activation. The PX domain is required for PLD1 translocation, mTORC1 activation, and cell size regulation. Finally, we show that the hVps34-PLD1 pathway acts independently of, and in parallel to, the Rag pathway in regulating amino acid activation of mTORC1.
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Affiliation(s)
- Mee-Sup Yoon
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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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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Han X, Yu R, Ji L, Zhen D, Tao S, Li S, Sun Y, Huang L, Feng Z, Li X, Han G, Schmidt M, Han L. InlB-mediated Listeria monocytogenes internalization requires a balanced phospholipase D activity maintained through phospho-cofilin. Mol Microbiol 2011; 81:860-80. [PMID: 21722201 DOI: 10.1111/j.1365-2958.2011.07726.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Internalization of Listeria monocytogenes into non-phagocytic cells is tightly controlled by host cell actin dynamics and cell membrane alterations. However, knowledge about the impact of phosphatidylcholine cleavage driven by host cell phospholipase D (PLD) on Listeria internalization into epithelial cells is limited. Here, we report that L. monocytogenes activates PLD in Vero cells during the internalization. With immunostaining it was shown that both PLD1 and PLD2 surrounded partially or completely the phagocytic cup of most L. monocytogenes. Either up- or down-regulation of PLD expression (activity) diminished Listeria internalization. Both PLD1 and PLD2 in Vero cells were required for efficient Listeria internalization, and could substitute for each other in the regulation of Listeria internalization. Further, exogenous InlB activated host cell PLD1 and PLD2 via the Met receptor, and restored host PLD activation by InlB-deficient L. monocytogenes. InlB-induced PLD activation and Listeria internalization were tightly controlled by phospho-cycling of cofilin. PLD1, but not PLD2, was involved in cofilin-mediated PLD activation and Listeria internalization. These data indicate that cofilin-dependent PLD activation induced by InlB may represent a novel regulation mechanism for efficient Listeria internalization into epithelial cells.
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Affiliation(s)
- Xuelin Han
- Department for Hospital Infection Control & Research, Institute of Disease Control & Prevention of PLA, Academy of Military Medical Sciences, Beijing, China
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Bodemann BO, Orvedahl A, Cheng T, Ram RR, Ou YH, Formstecher E, Maiti M, Hazelett CC, Wauson EM, Balakireva M, Camonis JH, Yeaman C, Levine B, White MA. RalB and the exocyst mediate the cellular starvation response by direct activation of autophagosome assembly. Cell 2011; 144:253-67. [PMID: 21241894 DOI: 10.1016/j.cell.2010.12.018] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 10/21/2010] [Accepted: 12/06/2010] [Indexed: 11/18/2022]
Abstract
The study of macroautophagy in mammalian cells has described induction, vesicle nucleation, and membrane elongation complexes as key signaling intermediates driving autophagosome biogenesis. How these components are recruited to nascent autophagosomes is poorly understood, and although much is known about signaling mechanisms that restrain autophagy, the nature of positive inductive signals that can promote autophagy remain cryptic. We find that the Ras-like small G protein, RalB, is localized to nascent autophagosomes and is activated on nutrient deprivation. RalB and its effector Exo84 are required for nutrient starvation-induced autophagocytosis, and RalB activation is sufficient to promote autophagosome formation. Through direct binding to Exo84, RalB induces the assembly of catalytically active ULK1 and Beclin1-VPS34 complexes on the exocyst, which are required for isolation membrane formation and maturation. Thus, RalB signaling is a primary adaptive response to nutrient limitation that directly engages autophagocytosis through mobilization of the core vesicle nucleation machinery.
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Affiliation(s)
- Brian O Bodemann
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390-9039, USA
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Eisinger DA, Ammer H. Epidermal growth factor treatment switches δ-opioid receptor-stimulated extracellular signal-regulated kinases 1 and 2 signaling from an epidermal growth factor to an insulin-like growth factor-1 receptor-dependent mechanism. Mol Pharmacol 2010; 79:326-35. [PMID: 21078885 DOI: 10.1124/mol.110.064956] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
δ-Opioid receptor (DOR)-induced activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) is mediated by the transactivation of epidermal growth factor (EGF) receptors. Here we demonstrate that in stably DOR-expressing human embryonic kidney (HEK) 293 (HEK/DOR) cells, down-regulation of EGF receptors by long-term EGF (0.1 μg for 18 h) treatment, but not by small interfering RNA, results in functional desensitization of EGF (10 ng/ml)-stimulated ERK1/2 signaling. In EGF receptor-desensitized (HEK/DOR(-EGFR)) cells, however, [d-Ala²,d-Leu⁵]enkephalin (1 μM) and etorphine (0.1 μM) retained their ability to stimulate ERK1/2 activation. The newly acquired signal transduction mechanism is insensitive to the EGF receptor blockers 4-(3-chloroanilino)-6,7-dimethoxyquinazoline (AG1478) and N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]-2-butynamide (CL-387,785), does not involve DOR internalization and activation of the focal adhesion kinase pp125FAK, but requires matrix metalloproteinase-dependent release of soluble growth factors. A supernatant transfer assay in which conditioned growth media of opioid-treated HEK/DOR and HEK/DOR(-EGFR) "donor" cells are used to stimulate ERK1/2 activity in DOR-lacking HEK293 wild type and HEK293(-EGFR) "acceptor" cells revealed that long-term EGF treatment produces a switch in the receptor tyrosine kinase (RTK) system transactivated by opioids. Using microfluidic electrophoresis, chemical inhibitors, phosphorylation-specific antibodies, and EGF receptor-deficient Chinese hamster ovary-K1 cells, we identified the release of an insulin-like growth factor-1 (IGF-1)-like peptide and activation of IGF-1 receptors in HEK/DOR(-EGFR) cells after DOR activation. A similar switch from a neurotrophic tyrosine kinase receptor type 1 to an IGF-1 receptor-dependent ERK1/2 signaling was observed for chronically nerve growth factor-treated neuroblastoma × glioma (NG108-15) cells. These results indicate that transactivation of the dominant RTK system in a given cellular setting may represent a general feature of opioids to maintain mitogenic signaling.
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Affiliation(s)
- Daniela A Eisinger
- Institute of Pharmacology, Toxicology and Pharmacy, University of Munich, Koeniginstrasse 16, 80539 Muenchen, Federal Republic of Germany.
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Ma WN, Park SY, Han JS. Role of phospholipase D1 in glucose-induced insulin secretion in pancreatic Beta cells. Exp Mol Med 2010; 42:456-64. [PMID: 20448441 DOI: 10.3858/emm.2010.42.6.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
As glucose is known to induce insulin secretion in pancreatic Beta cells, this study investigated the role of a phospholipase D (PLD)-related signaling pathway in insulin secretion caused by high glucose in the pancreatic Beta-cell line MIN6N8. It was found that the PLD activity and PLD1 expression were both increased by high glucose (33.3 mM) treatment. The dominant negative PLD1 inhibited glucose-induced Beta2 expression, and glucose-induced insulin secretion was blocked by treatment with 1-butanol or PLD1-siRNA. These results suggest that high glucose increased insulin secretion through a PLD1-related pathway. High glucose induced the binding of Arf6 to PLD1. Pretreatment with brefeldin A (BFA), an Arf inhibitor, decreased the PLD activity as well as the insulin secretion. Furthermore, BFA blocked the glucose-induced mTOR and p70S6K activation, while mTOR inhibition with rapamycin attenuated the glucose induced Beta2 expression and insulin secretion. Thus, when taken together, PLD1 would appear to be an important regulator of glucose-induced insulin secretion through an Arf6/PLD1/mTOR/p70S6K/ Beta2 pathway in MIN6N8 cells.
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Affiliation(s)
- Wei-na Ma
- Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul 133-791, Korea
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Corrotte M, Nyguyen APT, Harlay ML, Vitale N, Bader MF, Grant NJ. Ral isoforms are implicated in Fc gamma R-mediated phagocytosis: activation of phospholipase D by RalA. THE JOURNAL OF IMMUNOLOGY 2010; 185:2942-50. [PMID: 20679536 DOI: 10.4049/jimmunol.0903138] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phagocytosis is an essential element of the immune response permitting the elimination of pathogens, cellular debris, apoptotic cells, and tumor cells. Recently, both phospholipase D (PLD) isoforms, PLD1 and PLD2, were shown to be necessary for efficient FcgammaR-mediated phagocytosis. In this study, we investigated the role of a potential PLD regulator, the Ral GTPases RalA and RalB, in murine RAW 264.7 macrophages. Both Ral isoforms are expressed in macrophages and are transiently activated following FcgammaR stimulation. When Ral expression levels were varied using Ral mutants or interference RNA, phagocytosis assays revealed that Ral isoforms have antagonistic effects; RalA is a positive modulator, whereas RalB plays a negative role. We then focused on RalA and its possible relationship with PLD. The increase in PLD activity that occurs when phagocytosis is stimulated was inhibited in cells with reduced RalA protein, but it was unaffected by reduced levels of RalB. Furthermore, in macrophages transfected with dsRed-RalA and GFP-PLD1 or GFP-PLD2, RalA colocalized with PLD1 and PLD2 at the phagocytic cup during phagosome formation. Additional results obtained from immunoprecipitation of PLD from macrophages transfected with myc-RalA and hemagglutinin-tagged PLD1 or PLD2 indicated an enhanced interaction of RalA with both PLD isoforms during phagocytic stimulation. The increase in RalA and PLD1 interaction was transient and correlated with the time course of RalA activation. These findings reveal a novel pathway involving RalA and PLD in the regulation of FcgammaR-mediated phagocytosis.
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Affiliation(s)
- Matthias Corrotte
- Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Unité Propre de Recherche 3212, Strasbourg, France
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13
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Rankovic M, Jacob L, Rankovic V, Brandenburg LO, Schröder H, Höllt V, Koch T. ADP-ribosylation factor 6 regulates mu-opioid receptor trafficking and signaling via activation of phospholipase D2. Cell Signal 2009; 21:1784-93. [DOI: 10.1016/j.cellsig.2009.07.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 07/08/2009] [Accepted: 07/29/2009] [Indexed: 10/20/2022]
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Lee JS, Kim IS, Kim JH, Cho W, Suh PG, Ryu SH. Determination of EGFR endocytosis kinetic by auto-regulatory association of PLD1 with mu2. PLoS One 2009; 4:e7090. [PMID: 19763255 PMCID: PMC2739277 DOI: 10.1371/journal.pone.0007090] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 08/18/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Upon ligand binding, cell surface signaling receptors are internalized through a process tightly regulated by endocytic proteins and adaptor protein 2 (AP2) to orchestrate them. Although the molecular identities and roles of endocytic proteins are becoming clearer, it is still unclear what determines the receptor endocytosis kinetics which is mainly regulated by the accumulation of endocytic apparatus to the activated receptors. METHODOLOGY/PRINCIPAL FINDINGS Here we employed the kinetic analysis of endocytosis and adaptor recruitment to show that mu2, a subunit of AP2 interacts directly with phospholipase D (PLD)1, a receptor-associated signaling protein and this facilitates the membrane recruitment of AP2 and the endocytosis of epidermal growth factor receptor (EGFR). We also demonstrate that the PLD1-mu2 interaction requires the binding of PLD1 with phosphatidic acid, its own product. CONCLUSIONS/SIGNIFICANCE These results suggest that the temporal regulation of EGFR endocytosis is achieved by auto-regulatory PLD1 which senses the receptor activation and triggers the translocation of AP2 near to the activated receptor.
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Affiliation(s)
- Jun Sung Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, Republic of Korea
| | - Il Shin Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, Republic of Korea
| | - Jung Hwan Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, Republic of Korea
| | - Wonhwa Cho
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Pann-Ghill Suh
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, Republic of Korea
| | - Sung Ho Ryu
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, Republic of Korea
- * E-mail:
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15
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Lee CS, Kim KL, Jang JH, Choi YS, Suh PG, Ryu SH. The roles of phospholipase D in EGFR signaling. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:862-8. [DOI: 10.1016/j.bbalip.2009.04.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 04/23/2009] [Accepted: 04/24/2009] [Indexed: 10/20/2022]
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16
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Cheng Y, Qiu F, Ye YC, Tashiro SI, Onodera S, Ikejima T. Oridonin induces G2/M arrest and apoptosis via activating ERK-p53 apoptotic pathway and inhibiting PTK-Ras-Raf-JNK survival pathway in murine fibrosarcoma L929 cells. Arch Biochem Biophys 2009; 490:70-5. [PMID: 19699177 DOI: 10.1016/j.abb.2009.08.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 08/14/2009] [Accepted: 08/16/2009] [Indexed: 11/17/2022]
Abstract
Oridonin was reported to induce L929 cell apoptosis via ROS-mediated mitochondrial and ERK pathways; however, the precise mechanisms by which oridonin induces cell death remain unclear. Herein, we found that oridonin treatment induced an increase in G(2)/M phase cell percentage. And, G(2)/M phase arrest was associated with down-regulation of cell cycle related cdc2, cdc25c and cyclinB levels, as well as up-regulation of p21 and p-cdc2 levels. In addition, we discovered that interruption of p53 activation decreased oridonin-induced apoptosis, and blocking ERK by specific inhibitors or siRNA suppressed oridonin-induced p53 activation. Moreover, inhibition of PTK, protein kinase C, Ras, Raf or JNK activation increased oridonin-induced apoptosis. Also, the level of Ras, Raf or JNK was down-regulated by oridonin, and the inhibition of PTK, Ras, Raf activation decreased p-JNK level. In conclusion, oridonin induces L929 cell G(2)/M arrest and apoptosis, which is regulated by promoting ERK-p53 apoptotic pathway and suppressing PTK-mediated survival pathway.
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Affiliation(s)
- Yan Cheng
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China.
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17
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Akt-dependent and -independent mechanisms of mTOR regulation in cancer. Cell Signal 2009; 21:656-64. [PMID: 19166931 DOI: 10.1016/j.cellsig.2009.01.004] [Citation(s) in RCA: 286] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 01/02/2009] [Indexed: 12/25/2022]
Abstract
The protein kinase mTOR (mammalian target of rapamycin) is a critical regulator of cellular metabolism, growth, and proliferation. These processes contribute to tumor formation, and many cancers are characterized by aberrant activation of mTOR. Although activating mutations in mTOR itself have not been identified, deregulation of upstream components that regulate mTOR are prevalent in cancer. The prototypic mechanism of mTOR regulation in cells is through activation of the PI3K/Akt pathway, but mTOR receives input from multiple signaling pathways. This review will discuss Akt-dependent and -independent mechanisms of mTOR regulation in response to mitogenic signals, as well as its regulation in response to energy and nutrient-sensing pathways. Preclinical and clinical studies have demonstrated that tumors bearing genetic alterations that activate mTOR are sensitive to pharmacologic inhibition of mTOR. Elucidation of novel pathways that regulate mTOR may help identify predictive factors for sensitivity to mTOR inhibitors, and could provide new therapeutic targets for inhibiting the mTOR pathway in cancer. This review will also highlight pharmacologic approaches that inhibit mTOR via activation of the AMP-activated protein kinase (AMPK), an important inhibitor of the mTOR pathway and an emerging target in cancer.
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18
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Han L, Stope MB, de Jesús ML, Oude Weernink PA, Urban M, Wieland T, Rosskopf D, Mizuno K, Jakobs KH, Schmidt M. Direct stimulation of receptor-controlled phospholipase D1 by phospho-cofilin. EMBO J 2007; 26:4189-202. [PMID: 17853892 PMCID: PMC2230846 DOI: 10.1038/sj.emboj.7601852] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 08/02/2007] [Indexed: 01/10/2023] Open
Abstract
The activity state of cofilin, which controls actin dynamics, is driven by a phosphorylation-dephosphorylation cycle. Phosphorylation of cofilin by LIM-kinases results in its inactivation, a process supported by 14-3-3zeta and reversed by dephosphorylation by slingshot phosphatases. Here we report on a novel cellular function for the phosphorylation-dephosphorylation cycle of cofilin. We demonstrate that muscarinic receptor-mediated stimulation of phospholipase D1 (PLD1) is controlled by LIM-kinase, slingshot phosphatase as well as 14-3-3zeta, and requires phosphorylatable cofilin. Cofilin directly and specifically interacts with PLD1 and upon phosphorylation by LIM-kinase1, stimulates PLD1 activity, an effect mimicked by phosphorylation-mimic cofilin mutants. The interaction of cofilin with PLD1 is under receptor control and encompasses a PLD1-specific fragment (aa 585-712). Expression of this fragment suppresses receptor-induced cofilin-PLD1 interaction as well as PLD stimulation and actin stress fiber formation. These data indicate that till now designated inactive phospho-cofilin exhibits an active cellular function, and suggest that phospho-cofilin by its stimulatory effect on PLD1 may control a large variety of cellular functions.
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Affiliation(s)
- Li Han
- Institut für Pharmakologie, Universitätsklinikum Essen, Essen, Germany
| | - Matthias B Stope
- Institut für Pharmakologie, Universitätsklinikum Essen, Essen, Germany
| | | | | | - Martina Urban
- Institut für Pharmakologie, Universitätsklinikum Essen, Essen, Germany
| | - Thomas Wieland
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Klinische Medizin Mannheim der Universität Heidelberg, Mannheim, Germany
| | - Dieter Rosskopf
- Institut für Pharmakologie, Universitätsklinikum Essen, Essen, Germany
| | - Kensaku Mizuno
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Sendai, Miyagi, Japan
| | - Karl H Jakobs
- Institut für Pharmakologie, Universitätsklinikum Essen, Essen, Germany
| | - Martina Schmidt
- Institut für Pharmakologie, Universitätsklinikum Essen, Essen, Germany
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands
- Department of Molecular Pharmacology, University of Groningen, A. Deusinglaan 1, Groningen 9713 AV, The Netherlands. Tel.: +31 50 363 3322; Fax: +31 50 363 6908; E-mail:
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19
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Meyer J, Rhein M, Schiedlmeier B, Kustikova O, Rudolph C, Kamino K, Neumann T, Yang M, Wahlers A, Fehse B, Reuther GW, Schlegelberger B, Ganser A, Baum C, Li Z. Remarkable leukemogenic potency and quality of a constitutively active neurotrophin receptor, ΔTrkA. Leukemia 2007; 21:2171-80. [PMID: 17673903 DOI: 10.1038/sj.leu.2404882] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neurotrophins and their receptors play a key role in neurogenesis and survival. However, we and others have recently obtained evidence for a potential involvement of this receptor system in leukemia. To investigate mechanisms underlying the leukemogenic potential of activated neurotrophin receptor signaling, we analyzed in vivo leukemogenesis mediated by deltaTrkA, a mutant of TRKA (tropomyosin-related kinase A) isolated from a patient with acute myeloid leukemia (AML). Retroviral expression of deltaTrkA in myeloid 32D cells induced AML in syngeneic C3H/Hej mice (n=11/11, latency approximately 4 weeks). C57Bl/6J mice transplanted with deltaTrkA-transduced primary lineage negative (Lin-) bone marrow cells died of a transient polyclonal AML (n=7/15, latency of <12 days). Serial transplantation of AML cells did not re-induce this disease but rather acute lymphoblastic leukemia (ALL, latency >78 days). All primary recipients surviving the early AML developed clonal ALL or myeloid leukemia (latency >72 days) that required additional genetic lesions. PI3K and mTOR-raptor were identified as the crucial mediators of leukemic transformation, whereas STAT and MAP kinase signaling pathways were not activated. Thus, our findings reveal potent and unique transforming properties of altered neurotrophin receptor signaling in leukemogenesis, and encourage further analyses of neurotrophin receptors and downstream signaling events in hematological malignancies.
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Affiliation(s)
- J Meyer
- Department of Experimental Hematology, Hannover Medical School, Hannover, Germany
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20
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Fan S, Meng Q, Laterra JJ, Rosen EM. Ras effector pathways modulate scatter factor-stimulated NF-kappaB signaling and protection against DNA damage. Oncogene 2007; 26:4774-96. [PMID: 17297451 DOI: 10.1038/sj.onc.1210271] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Scatter factor (SF) (hepatocyte growth factor) is a pleiotrophic cytokine that accumulates within tumors in vivo and protects tumor cells against cytotoxicity and apoptosis due to DNA damaging agents in vitro. Previous studies have established that SF-mediated cell protection involves antiapoptotic signaling from its receptor (c-Met) to PI3 kinase --> c-Akt --> Pak1 (p21-activated kinase -1) --> NF-kappaB (nuclear factor-kappa B). Here, we found that Ras proteins (H-Ras and R-Ras) enhance SF-mediated activation of NF-kappaB and protection of DU-145 and MDCK (Madin-Darby canine kidney) cells against the topoisomerase IIalpha inhibitor adriamycin. Studies of Ras effector loop mutants and their downstream effectors suggest that Ras/PI3 kinase and Ras/Raf1 pathways contribute to SF stimulation of NF-kappaB signaling and cell protection. Further studies revealed that Raf1 positively regulates the ability of SF to stimulate NF-kappaB activity and cell protection. The ability of Raf1 to stimulate NF-kappaB activity was not due to the classical Raf1 --> MEK1/2 --> ERK1/2 pathway. However, we found that a MEK3/6 --> p38 pathway contributes to SF-mediated activation of NF-kappaB. In contrast, RalA, a target of the Ras/RalGDS pathway negatively regulated the ability of SF to stimulate NF-kappaB activity and cell protection. Ras, Raf1 and RalA modulate SF stimulation of NF-kappaB activity, in part, by regulating IkappaB kinase (IKK)-beta kinase activity. These findings suggest that Ras/Raf1/RalA pathways may converge to modulate NF-kappaB activation and SF-mediated survival signaling at the IKK complex and/or a kinase upstream of this complex.
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Affiliation(s)
- S Fan
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057-1469, USA
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21
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Oude Weernink PA, López de Jesús M, Schmidt M. Phospholipase D signaling: orchestration by PIP2 and small GTPases. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2007; 374:399-411. [PMID: 17245604 PMCID: PMC2020506 DOI: 10.1007/s00210-007-0131-4] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 12/20/2006] [Indexed: 11/12/2022]
Abstract
Hydrolysis of phosphatidylcholine by phospholipase D (PLD) leads to the generation of the versatile lipid second messenger, phosphatidic acid (PA), which is involved in fundamental cellular processes, including membrane trafficking, actin cytoskeleton remodeling, cell proliferation and cell survival. PLD activity can be dramatically stimulated by a large number of cell surface receptors and is elaborately regulated by intracellular factors, including protein kinase C isoforms, small GTPases of the ARF, Rho and Ras families and, particularly, by the phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP(2)). PIP(2) is well known as substrate for the generation of second messengers by phospholipase C, but is now also understood to recruit and/or activate a variety of actin regulatory proteins, ion channels and other signaling proteins, including PLD, by direct interaction. The synthesis of PIP(2) by phosphoinositide 5-kinase (PIP5K) isoforms is tightly regulated by small GTPases and, interestingly, by PA as well, and the concerted formation of PIP(2) and PA has been shown to mediate receptor-regulated cellular events. This review highlights the regulation of PLD by membrane receptors, and describes how the close encounter of PLD and PIP5K isoforms with small GTPases permits the execution of specific cellular functions.
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Affiliation(s)
| | | | - Martina Schmidt
- />Department of Molecular Pharmacology, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
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22
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Oude Weernink PA, Han L, Jakobs KH, Schmidt M. Dynamic phospholipid signaling by G protein-coupled receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1768:888-900. [PMID: 17054901 DOI: 10.1016/j.bbamem.2006.09.012] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 09/18/2006] [Accepted: 09/18/2006] [Indexed: 11/19/2022]
Abstract
G protein-coupled receptors (GPCRs) control a variety of fundamental cellular processes by regulating phospholipid signaling pathways. Essential for signaling by a large number of receptors is the hydrolysis of the membrane phosphoinositide PIP(2) by phospholipase C (PLC) into the second messengers IP(3) and DAG. Many receptors also stimulate phospholipase D (PLD), leading to the generation of the versatile lipid, phosphatidic acid. Particular PLC and PLD isoforms take differential positions in receptor signaling and are additionally regulated by small GTPases of the Ras, Rho and ARF families. It is now recognized that the PLC substrate, PIP(2), has signaling capacity by itself and can, by direct interaction, affect the activity and subcellular localization of PLD and several other proteins. As expected, the synthesis of PIP(2) by phosphoinositide 5-kinases is tightly regulated as well. In this review, we present an overview of how these signaling pathways are governed by GPCRs, explain the molecular basis for the spatially and temporally organized, highly dynamic quality of phospholipid signaling, and point to the functional connection of the pathways.
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Affiliation(s)
- Paschal A Oude Weernink
- Institut für Pharmakologie, Universitätsklinikum Essen, Hufelandstrasse 55, 45122 Essen, Germany.
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23
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De Jesús ML, Stope MB, Weernink PAO, Mahlke Y, Börgermann C, Ananaba VN, Rimmbach C, Rosskopf D, Michel MC, Jakobs KH, Schmidt M. Cyclic AMP-dependent and Epac-mediated activation of R-Ras by G protein-coupled receptors leads to phospholipase D stimulation. J Biol Chem 2006; 281:21837-21847. [PMID: 16754664 DOI: 10.1074/jbc.m604156200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activation of the Ras-related GTPase R-Ras, which has been implicated in the regulation of various cellular functions, by G protein-coupled receptors (GPCRs) was studied in HEK-293 cells stably expressing the M3 muscarinic acetylcholine receptor (mAChR), which can couple to several types of heterotrimeric G proteins. Activation of the receptor induced a very rapid and transient activation of R-Ras. Studies with inhibitors and activators of various signaling pathways indicated that R-Ras activation by the M3 mAChR is dependent on cyclic AMP formation but is independent of protein kinase A. Similar to the rather promiscuous M3 mAChR, two typical G(s)-coupled receptors also induced R-Ras activation. The receptor actions were mimicked by an Epac-specific cyclic AMP analog and suppressed by depletion of endogenous Epac1 by small interfering RNAs, as well as expression of a cyclic AMP binding-deficient Epac1 mutant, but not by expression of dominant negative Rap GTPases. In vitro studies demonstrated that Epac1 directly interacts with R-Ras and catalyzes GDP/GTP exchange at this GTPase. Finally, it is shown that the cyclic AMP- and Epac-activated R-Ras plays a major role in the M3 mAChR-mediated stimulation of phospholipase D but not phospholipase C. Collectively, our data indicate that GPCRs rapidly activate R-Ras, that R-Ras activation by the GPCRs is apparently directly induced by cyclic AMP-regulated Epac proteins, and that activated R-Ras specifically controls GPCR-mediated phospholipase D stimulation.
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Affiliation(s)
| | - Matthias B Stope
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
| | | | - Yvonne Mahlke
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
| | - Christof Börgermann
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
| | - Viktoria N Ananaba
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
| | - Christian Rimmbach
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
| | - Dieter Rosskopf
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
| | - Martin C Michel
- Department of Pharmacology and Pharmacotherapy, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Karl H Jakobs
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
| | - Martina Schmidt
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany; Department of Pharmacology and Pharmacotherapy, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
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24
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Lee JS, Kim JH, Jang IH, Kim HS, Han JM, Kazlauskas A, Yagisawa H, Suh PG, Ryu SH. Phosphatidylinositol (3,4,5)-trisphosphate specifically interacts with the phox homology domain of phospholipase D1 and stimulates its activity. J Cell Sci 2005; 118:4405-13. [PMID: 16179605 DOI: 10.1242/jcs.02564] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Phospholipase D (PLD), which catalyzes the hydrolysis of phosphatidylcholine to phosphatidic acid and choline, plays key roles in cellular signal transduction by mediating extracellular stimuli including hormones, growth factors, neurotransmitters, cytokines and extracellular matrix molecules. The molecular mechanisms by which domains regulate the activity of PLD - especially the phox homology (PX) domain - have not been fully elucidated. In this study, we have examined the properties of the PX domains of PLD1 and PLD2 in terms of phosphoinositide binding and PLD activity regulation. Interestingly, the PX domain of PLD1, but not that of PLD2, was found to specifically interact with phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3). We found that mutation of the conserved arginine at position 179 of the PLD1 PX domain to lysine or to alanine (R179A or R179K, respectively) disrupts PtdIns(3,4,5)P3 binding. In NIH-3T3 cells, the EGFP-PLD1 PX wild-type domain, but not the two mutants, localized to the plasma membrane after 5-minute treatment with platelet-derived growth factor (PDGF). The enzymatic activity of PLD1 was stimulated by adding PtdIns(3,4,5)P3 in vitro. Treatment with PDGF resulted in the significant increase of PLD1 activity and phosphorylation of the downstream extracellular signal-regulated kinases (ERKs), which was blocked by pre-treatment of HEK 293 cells with phosphoinositide 3-kinase (PI3K) inhibitor after the endogenous PLD2 had been depleted by siRNA specific for PLD2. Nevertheless, both PLD1 mutants (which cannot interact with PtdIns(3,4,5)P3) did not respond to treatment with PDGF. Moreover, PLD1 was activated in HepG2 cells stably expressing the Y40/51 mutant of PDGF receptor that is required for the binding with PI3K. Our results suggest that the PLD1 PX domain enables PLD1 to mediate signal transduction via ERK1/2 by providing a direct binding site for PtdIns(3,4,5)P3 and by activating PLD1.
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Affiliation(s)
- Jun Sung Lee
- Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea
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25
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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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26
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Abstract
Dynamic modulation of ion channels can produce dramatic alterations of electrical excitability in cardiac myocytes. This study addresses the effects of the Src family tyrosine kinase Fyn on Na
V
1.5 cardiac sodium channels. Sodium currents were acquired by whole cell recording on HEK-293 cells transiently expressing Na
V
1.5. Acute treatment of cells with insulin caused a depolarizing shift in steady-state inactivation, an effect eliminated by the Src-specific tyrosine kinase inhibitor PP2. Sodium channels were coexpressed with either constitutively active (Fyn
CA
) or catalytically inactive (Fyn
KD
) variants of Fyn. Fyn
CA
caused a 10-mV depolarizing shift of steady-state inactivation compared with Fyn
KD
without altering the activation conductance-voltage relationship. Comparable effects of these Fyn variants were obtained with whole-cell and perforated-patch recording. Tyrosine phosphorylation of immunoprecipitated Na
V
1.5 was increased in cells expressing Fyn
CA
compared with Fyn
KD
. We show that Fyn is present in rat cardiac myocytes, and that Na
V
1.5 channels from these myocytes are tyrosine-phosphorylated. In HEK-293 cells the effect of Fyn
CA
on Na
V
1.5 inactivation is abolished by the single point mutation Y1495F, a residue located within the cytoplasmic linker between the third and fourth homologous domains of the sodium channel. We provide evidence that this linker is a substrate for Fyn in vitro, and that Y1495 is a preferred phosphorylation site. These results suggest that cardiac sodium channels are physiologically relevant targets of Src family tyrosine kinases.
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Affiliation(s)
- Christopher A Ahern
- Department of Physiology, Institute of Hyperexcitability, Jefferson Medical College, Philadelphia, Pa 19107, USA
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27
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Frankel P, Aronheim A, Kavanagh E, Balda MS, Matter K, Bunney TD, Marshall CJ. RalA interacts with ZONAB in a cell density-dependent manner and regulates its transcriptional activity. EMBO J 2005; 24:54-62. [PMID: 15592429 PMCID: PMC544910 DOI: 10.1038/sj.emboj.7600497] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2004] [Accepted: 11/05/2004] [Indexed: 11/08/2022] Open
Abstract
Ral proteins are members of the Ras superfamily of small GTPases and are involved in signalling pathways for actin cytoskeleton remodelling, cell cycle control, cellular transformation and vesicle transport. To identify novel RalA effector proteins, we used the reverse Ras recruitment system and found that RalA interacts with a Y-box transcription factor, ZO-1-associated nucleic acid-binding protein (ZONAB), in a GTP-dependent manner. The amount of the RalA-ZONAB complex increases as epithelial cells become more dense and increase cell contacts. The RalA-ZONAB interaction results in a relief of transcriptional repression of a ZONAB-regulated promoter. Additionally, expression of oncogenic Ras alleviates transcriptional repression by ZONAB in a RalA-dependent manner. The data presented here implicate the RalA/ZONAB interaction in the regulation of ZONAB function.
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Affiliation(s)
- Paul Frankel
- Oncogene Team, Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, UK
| | - Ami Aronheim
- Department of Molecular Genetics, the B Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Emma Kavanagh
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
| | - Maria S Balda
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
| | - Karl Matter
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
| | - Tom D Bunney
- Lipid Signalling Team, Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, UK
| | - Christopher J Marshall
- Oncogene Team, Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, UK
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28
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Abstract
Phospholipase D catalyses the hydrolysis of the phosphodiester bond of glycerophospholipids to generate phosphatidic acid and a free headgroup. Phospholipase D activities have been detected in simple to complex organisms from viruses and bacteria to yeast, plants, and mammals. Although enzymes with broader selectivity are found in some of the lower organisms, the plant, yeast, and mammalian enzymes are selective for phosphatidylcholine. The two mammalian phospholipase D isoforms are regulated by protein kinases and GTP binding proteins of the ADP-ribosylation and Rho families. Mammalian and yeast phospholipases D are also potently stimulated by phosphatidylinositol 4,5-bisphosphate. This review discusses the identification, characterization, structure, and regulation of phospholipase D. Genetic and pharmacological approaches implicate phospholipase D in a diverse range of cellular processes that include receptor signaling, control of intracellular membrane transport, and reorganization of the actin cytoskeleton. Most ideas about phospholipase D function consider that the phosphatidic acid product is an intracellular lipid messenger. Candidate targets for phospholipase-D-generated phosphatidic acid include phosphatidylinositol 4-phosphate 5-kinases and the raf protein kinase. Phosphatidic acid can also be converted to two other lipid mediators, diacylglycerol and lyso phosphatidic acid. Coordinated activation of these phospholipase-D-dependent pathways likely accounts for the pleitropic roles for these enzymes in many aspects of cell regulation.
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Affiliation(s)
- Mark McDermott
- Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 27599-7090, USA
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29
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Keiper M, Stope MB, Szatkowski D, Böhm A, Tysack K, Vom Dorp F, Saur O, Oude Weernink PA, Evellin S, Jakobs KH, Schmidt M. Epac- and Ca2+ -controlled activation of Ras and extracellular signal-regulated kinases by Gs-coupled receptors. J Biol Chem 2004; 279:46497-508. [PMID: 15319437 DOI: 10.1074/jbc.m403604200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have recently reported that two typical Gs-coupled receptors, the beta2-adrenergic receptor and the receptor for prostaglandin E1, stimulate phospholipase C-epsilon (PLC-epsilon) and increase intracellular Ca2+ concentration ([Ca2+]i) in HEK-293 cells and N1E-115 neuroblastoma cells, respectively, by a pathway involving Epac1, a cAMP-activated and Rap-specific guanine nucleotide exchange factor (GEF), and the GTPase Rap2B. Here we have demonstrated that these Gs-coupled receptors use this pathway to activate H-Ras and the extracellular signal-regulated kinases 1 and 2 (ERK1/2). Specifically, agonist activation of the receptors resulted in activation of H-Ras and ERK1/2. The latter action was suppressed by dominant negative H-Ras, but not Rap1A. The receptor actions were independent of protein kinase A but fully mimicked by an Epac-specific cAMP analog as well as by a constitutively active Rap2B mutant. On the other hand, a cAMP-binding-deficient Epac1 mutant, the Rap GTPase-activating proteinII, and a dominant negative Rap2B mutant suppressed receptor- and Epac-mediated activation of H-Ras and ERK1/2. Finally, we have demonstrated that activation of H-Ras and ERK1/2 requires the lipase activity of PLC-epsilon and the subsequent [Ca2+]i increase, suggesting that H-Ras activation is mediated by a Ca2+ -activated GEF. In line with this hypothesis, receptor-mediated activation of H-Ras and ERK1/2 was strongly enhanced by expression of RasGRP1, a Ca2+ -regulated Ras-GEF. Collectively, our data indicated that Gs-coupled receptors can activate H-Ras and subsequently the mitogen-activated protein kinases ERK1/2 by a Ca2+ -activated Ras-GEF, possibly RasGRP1, mediated by cAMP-activated Epac proteins, which then lead via Rap2B and PLC-epsilon stimulation to [Ca2+]i increase.
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Affiliation(s)
- Melanie Keiper
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany
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Oliva JL, Zarich N, Martínez N, Jorge R, Castrillo A, Azañedo M, García-Vargas S, Gutiérrez-Eisman S, Juarranz A, Boscá L, Gutkind JS, Rojas JM. The P34G mutation reduces the transforming activity of K-Ras and N-Ras in NIH 3T3 cells but not of H-Ras. J Biol Chem 2004; 279:33480-91. [PMID: 15181015 DOI: 10.1074/jbc.m404058200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ras proteins (H-, N-, and K-Ras) operate as molecular switches in signal transduction cascades controlling cell proliferation, differentiation, or apoptosis. The interaction of Ras with its effectors is mediated by the effector-binding loop, but different data about Ras location to plasma membrane subdomains and new roles for some docking/scaffold proteins point to signaling specificities of the different Ras proteins. To investigate the molecular mechanisms for these specificities, we compared an effector loop mutation (P34G) of three Ras isoforms (H-, N-, and K-Ras4B) for their biological and biochemical properties. Although this mutation diminished the capacity of Ras proteins to activate the Raf/ERK and the phosphatidylinositol 3-kinase/AKT pathways, the H-Ras V12G34 mutant retained the ability to cause morphological transformation of NIH 3T3 fibroblasts, whereas both the N-Ras V12G34 and the K-Ras4B V12G34 mutants were defective in this biological activity. On the other hand, although both the N-Ras V12G34 and the K-Ras4B V12G34 mutants failed to promote activation of the Ral-GDS/Ral A/PLD and the Ras/Rac pathways, the H-Ras V12G34 mutant retained the ability to activate these signaling pathways. Interestingly, the P34G mutation reduced specifically the N-Ras and K-Ras4B in vitro binding affinity to Ral-GDS, but not in the case of H-Ras. Thus, independently of Ras location to membrane subdomains, there are marked differences among Ras proteins in the sensitivity to an identical mutation (P34G) affecting the highly conserved effector-binding loop.
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Affiliation(s)
- José Luis Oliva
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), 28220 Majadahonda, Madrid, Spain
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31
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Stope MB, Vom Dorp F, Szatkowski D, Böhm A, Keiper M, Nolte J, Oude Weernink PA, Rosskopf D, Evellin S, Jakobs KH, Schmidt M. Rap2B-dependent stimulation of phospholipase C-epsilon by epidermal growth factor receptor mediated by c-Src phosphorylation of RasGRP3. Mol Cell Biol 2004; 24:4664-76. [PMID: 15143162 PMCID: PMC416426 DOI: 10.1128/mcb.24.11.4664-4676.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2003] [Revised: 01/16/2004] [Accepted: 03/08/2004] [Indexed: 12/21/2022] Open
Abstract
Receptor tyrosine kinase regulation of phospholipase C-epsilon (PLC-epsilon), which is under the control of Ras-like and Rho GTPases, was studied with HEK-293 cells endogenously expressing PLC-coupled epidermal growth factor (EGF) receptors. PLC and Ca(2+) signaling by the EGF receptor, which activated both PLC-gamma1 and PLC-epsilon, was specifically suppressed by inactivation of Ras-related GTPases with clostridial toxins and expression of dominant-negative Rap2B. EGF induced rapid and sustained GTP loading of Rap2B, binding of Rap2B to PLC-epsilon, and Rap2B-dependent translocation of PLC-epsilon to the plasma membrane. GTP loading of Rap2B by EGF was inhibited by chelation of intracellular Ca(2+) and expression of lipase-inactive PLC-gamma1 but not of PLC-epsilon. Expression of RasGRP3, a Ca(2+)/diacylglycerol-regulated guanine nucleotide exchange factor for Ras-like GTPases, but not expression of various other exchange factors enhanced GTP loading of Rap2B and PLC/Ca(2+) signaling by the EGF receptor. EGF induced tyrosine phosphorylation of RasGRP3, but not RasGRP1, apparently caused by c-Src; inhibition of c-Src interfered with EGF-induced Rap2B activation and PLC stimulation. Collectively, these data suggest that the EGF receptor triggers activation of Rap2B via PLC-gamma1 activation and tyrosine phosphorylation of RasGRP3 by c-Src, finally resulting in stimulation of PLC-epsilon.
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Affiliation(s)
- Matthias B Stope
- Institut für Pharmakologie, Universitätsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany.
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32
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Grunicke HH, Spitaler M, Mwanjewe J, Schwaiger W, Jenny M, Ueberall F. Regulation of cell survival by atypical protein kinase C isozymes. ADVANCES IN ENZYME REGULATION 2004; 43:213-28. [PMID: 12791393 DOI: 10.1016/s0065-2571(02)00032-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Hans H Grunicke
- Institute of Medical Chemistry and Biochemistry, University of Innsbruck, Fritz pregel Str 3, A-6020, Innsbruck, Austria.
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Huang C, Hujer KM, Wu Z, Miller RT. The Ca2+-sensing receptor couples to Galpha12/13 to activate phospholipase D in Madin-Darby canine kidney cells. Am J Physiol Cell Physiol 2004; 286:C22-30. [PMID: 12954603 DOI: 10.1152/ajpcell.00229.2003] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Ca2+-sensing receptor (CaR) couples to multiple G proteins involved in distinct signaling pathways: Galphai to inhibit the activity of adenylyl cyclase and activate ERK, Galphaq to stimulate phospholipase C and phospholipase A2, and Gbetagamma to stimulate phosphatidylinositol 3-kinase. To determine whether the receptor also couples to Galpha12/13, we investigated the signaling pathway by which the CaR regulates phospholipase D (PLD), a known Galpha12/13 target. We established Madin-Darby canine kidney (MDCK) cell lines that stably overexpress the wild-type CaR (CaRWT) or the nonfunctional mutant CaRR796W as a negative control, prelabeled these cells with [3H]palmitic acid, and measured CaR-stimulated PLD activity as the formation of [3H]phosphatidylethanol (PEt). The formation of [3H]PEt increased in a time-dependent manner in the cells that overexpress the CaRWT but not the CaRR796W. Treatment of the cells with C3 exoenzyme inhibited PLD activity, which indicates that the CaR activates the Rho family of small G proteins, targets of Galpha12/13. To determine which G protein(s) the CaR couples to in order to activate Rho and PLD, we pretreated the cells with pertussis toxin to inactivate Galphai or coexpressed regulators of G protein-signaling (RGS) proteins to attenuate G protein signaling (RGS4 for Galphai and Galphaq, and a p115RhoGEF construct containing the RGS domain for Galpha12/13). Overexpression of p115RhoGEF-RGS in the MDCK cells that overexpress CaRWT inhibited extracellular Ca2+-stimulated PLD activity, but pretreatment of cells with pertussis toxin and overexpression of RGS4 were without effect. The involvement of other signaling components such as protein kinase C, ADP-ribosylation factor, and phosphatidylinositol biphosphate was excluded. These findings demonstrate that the CaR couples to Galpha12/13 to regulate PLD via a Rho-dependent mechanism and does so independently of Galphai and Galphaq. This suggests that the CaR may regulate cytoskeleton via Galpha12/13, Rho, and PLD.
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Affiliation(s)
- Chunfa Huang
- Division of Nephrology, Department of Medicine, Case Western Reserve University, Louis Stokes Veteran Affairs Medical Center, 10701 East Boulevard 151W, Cleveland, OH 44106, USA.
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Koch T, Brandenburg LO, Liang Y, Schulz S, Beyer A, Schröder H, Höllt V. Phospholipase D2 modulates agonist-induced µ-opioid receptor desensitization and resensitization. J Neurochem 2003; 88:680-8. [PMID: 14720217 DOI: 10.1046/j.1471-4159.2003.02189.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Receptor phosphorylation, arrestin binding, uncoupling from G protein and subsequent endocytosis have been implicated in G protein-coupled receptor desensitization after chronic agonist exposure. In search of proteins regulating the mu-opioid receptor endocytosis, we have recently established that activation of phospholipase D (PLD)2 is required for agonist-induced mu-opioid receptor endocytosis. In this study, we determined the effect of PLD2 activity on the desensitization and resensitization rate of the mu-opioid receptor. We clearly demonstrated that inhibition of PLD2-mediated phosphatidic acid formation by alcohol (1-butanol or ethanol) or overexpression of a dominant negative mutant of PLD2 prevented agonist-mediated endocytosis and resulted in a faster desensitization rate of the mu-opioid receptor after chronic (D-Ala2, Me Phe4, Glyol5)enkephalin treatment in human embryonic kidney 293 cells. Moreover, inhibition of PLD2 activity led to an impairment of the resensitization rate of the mu-opioid receptor. In summary, our data strongly suggest that PLD2 is a modulator of agonist-induced endocytosis, desensitization and resensitization of the mu-opioid receptor.
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Affiliation(s)
- Thomas Koch
- Department of Pharmacology and Toxicology, Otto-von-Guericke University, Magdeburg, Germany.
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35
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Abstract
Insulin-stimulated Glut-4 translocation is regulated through a complex pathway. Increasing attention is being paid to the role undertaken in this process by Phospholipase D, a signal transduction-activated enzyme that generates the lipid second-messenger phosphatidic acid. Phospholipase D facilitates Glut-4 translocation at potentially multiple steps in its outward movement. Current investigation is centered on Phospholipase D promotion of Glut-4-containing membrane vesicle trafficking and vesicle fusion into the plasma membrane, in part through activation of atypical protein kinase C isoforms.
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Affiliation(s)
- Ping Huang
- Department of Pharmacology and the Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA
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36
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Jang IH, Lee S, Park JB, Kim JH, Lee CS, Hur EM, Kim IS, Kim KT, Yagisawa H, Suh PG, Ryu SH. The direct interaction of phospholipase C-gamma 1 with phospholipase D2 is important for epidermal growth factor signaling. J Biol Chem 2003; 278:18184-90. [PMID: 12646582 DOI: 10.1074/jbc.m208438200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epidermal growth factor (EGF) receptor has an important role in cellular proliferation, and the enzymatic activity of phospholipase C (PLC)-gamma1 is regarded to be critical for EGF-induced mitogenesis. In this study, we report for the first time a phospholipase complex composed of PLC-gamma1 and phospholipase D2 (PLD2). PLC-gamma1 is co-immunoprecipitated with PLD2 in COS-7 cells. The results of in vitro binding analysis and co-immunoprecipitation analysis in COS-7 cells show that the Src homology (SH) 3 domain of PLC-gamma1 binds to the proline-rich motif within the Phox homology (PX) domain of PLD2. The interaction between PLC-gamma1 and PLD2 is EGF stimulation-dependent and potentiates EGF-induced inositol 1,4,5-trisphosphate (IP(3)) formation and Ca(2+) increase. Mutating Pro-145 and Pro-148 within the PX domain of PLD2 to leucines disrupts the interaction between PLC-gamma1 and PLD2 and fails to potentiate EGF-induced IP(3) formation and Ca(2+) increase. However, neither PLD2 wild type nor PLD2 mutant affects the EGF-induced tyrosine phosphorylation of PLC-gamma1. These findings suggest that, upon EGF stimulation, PLC-gamma1 directly interacts with PLD2 and this interaction is important for PLC-gamma1 activity.
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Affiliation(s)
- Il Ho Jang
- Department of Life Science and Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
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37
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Mirey G, Balakireva M, L'Hoste S, Rossé C, Voegeling S, Camonis J. A Ral guanine exchange factor-Ral pathway is conserved in Drosophila melanogaster and sheds new light on the connectivity of the Ral, Ras, and Rap pathways. Mol Cell Biol 2003; 23:1112-24. [PMID: 12529414 PMCID: PMC140692 DOI: 10.1128/mcb.23.3.1112-1124.2003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2002] [Revised: 06/18/2002] [Accepted: 10/21/2002] [Indexed: 12/22/2022] Open
Abstract
Ras GTPases are central to many physiological and pathological signaling pathways and act via a combination of effectors. In mammals, at least three Ral exchange factors (RalGEFs) contain a Ras association domain and constitute a discrete subgroup of Ras effectors. Despite their ability to bind activated Rap as well as activated Ras, they seem to act downstream of Ras but not downstream of Rap. We have revisited the Ras/Rap-Ral connections in Drosophila melanogaster by using iterative two-hybrid screens with these three GTPases as primary baits and a subsequent genetic approach. We show that (i) the Ral-centered protein network appears to be extremely conserved in human and flies, (ii) in this network, RGL is a functional Drosophila orthologue of RalGEFs, and (iii) the RGL-Ral pathway functionally interacts with both the Ras and Rap pathways. Our data do not support the paradigmatic model where Ral is in the effector pathway of Ras. They reveal a signaling circuitry where Ral is functionally downstream of the Rap GTPase, at odds with the pathways described for mammalian cell lines. Thus, in vivo data show variations in the connectivity of pathways described for cell lines which might display only a subset of the biological possibilities.
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Affiliation(s)
- Gladys Mirey
- Groupe d'Analyse des Réseaux de Transduction, Institut Curie, Inserm U-528, 75248 Paris Cedex 05, France
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38
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Xu L, Frankel P, Jackson D, Rotunda T, Boshans RL, D'Souza-Schorey C, Foster DA. Elevated phospholipase D activity in H-Ras- but not K-Ras-transformed cells by the synergistic action of RalA and ARF6. Mol Cell Biol 2003; 23:645-54. [PMID: 12509462 PMCID: PMC151535 DOI: 10.1128/mcb.23.2.645-654.2003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Phospholipase D (PLD) activity is elevated in response to the oncogenic stimulus of H-Ras but not K-Ras. H-Ras and K-Ras have been reported to localize to different membrane microdomains, with H-Ras localizing to caveolin-enriched light membrane fractions. We reported previously that PLD activity elevated in response to mitogenic stimulation is restricted to the caveolin-enriched light membrane fractions. PLD activity in H-Ras-transformed cells is dependent upon RalA, and consistent with a lack of elevated PLD activity in K-Ras-transformed cells, RalA was not activated in K-Ras-transformed cells. Although H-Ras-induced PLD activity is dependent upon RalA, an activated mutant of RalA is not sufficient to elevate PLD activity. We reported previously that RalA interacts with PLD activating ADP ribosylation factor (ARF) proteins. In cells transformed by H-Ras, we found increased coprecipitation of ARF6 with RalA. Moreover, ARF6 colocalized with RalA in light membrane fractions. Interestingly, ARF6 protein levels were elevated in H-Ras- but not K-Ras-transformed cells. A dominant-negative mutant of ARF6 inhibited PLD activity in H-Ras-transformed NIH 3T3 cells. Activated mutants of either ARF6 or RalA were not sufficient to elevate PLD activity in NIH 3T3 cells; however, expression of both activated RalA and activated ARF6 in NIH 3T3 cells led to increased PLD activity. These data suggest a model whereby H-Ras stimulates the activation of both RalA and ARF6, which together lead to the elevation of PLD activity.
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Affiliation(s)
- Lizhong Xu
- Department of Biological Sciences, Hunter College of The City University of New York, New York, New York 10021, USA
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39
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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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40
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Zhu T, Ling L, Lobie PE. Identification of a JAK2-independent pathway regulating growth hormone (GH)-stimulated p44/42 mitogen-activated protein kinase activity. GH activation of Ral and phospholipase D is Src-dependent. J Biol Chem 2002; 277:45592-603. [PMID: 12218045 DOI: 10.1074/jbc.m201385200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have demonstrated here that growth hormone (GH) stimulates the formation of the active GTP-bound form of both RalA and RalB in NIH-3T3 cells. Full activation of RalA and RalB by GH required the combined activity of c-Src and JAK2, both kinases activated by GH independent of the other. Activation of RalA and RalB by growth hormone did not require the activity of JAK2 per se. Ras was also activated by GH and was required for the GH-stimulated formation of GTP-bound RalA and RalB. Activation of RalA by GH subsequently resulted in increased phospholipase D activity and the formation of its metabolite, phosphatidic acid. GH-stimulated RalA-phospholipase D-dependent formation of phosphatidic acid was required for activation of p44/42 MAPK and subsequent Elk-1-mediated transcription stimulated by GH. Thus we report the identification of a JAK2-independent pathway regulating GH-stimulated p44/42 MAPK activity.
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Affiliation(s)
- Tao Zhu
- Institute of Molecular and Cell Biology, Singapore, Republic of Singapore
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41
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Han JM, Kim Y, Lee JS, Lee CS, Lee BD, Ohba M, Kuroki T, Suh PG, Ryu SH. Localization of phospholipase D1 to caveolin-enriched membrane via palmitoylation: implications for epidermal growth factor signaling. Mol Biol Cell 2002; 13:3976-88. [PMID: 12429840 PMCID: PMC133608 DOI: 10.1091/mbc.e02-02-0100] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Phospholipase D (PLD) has been suggested to mediate epidermal growth factor (EGF) signaling. However, the molecular mechanism of EGF-induced PLD activation has not yet been elucidated. We investigated the importance of the phosphorylation and compartmentalization of PLD1 in EGF signaling. EGF treatment of COS-7 cells transiently expressing PLD1 stimulated PLD1 activity and induced PLD1 phosphorylation. The EGF-induced phosphorylation of threonine147 was completely blocked and the activity of PLD1 attenuated by point mutations (S2A/T147A/S561A) of PLD1 phosphorylation sites. The expression of a dominant negative PKCalpha mutant by adenovirus-mediated gene transfer greatly inhibited the phosphorylation and activation of PLD1 induced by EGF in PLD1-transfected COS-7 cells. EGF-induced PLD1 phosphorylation occurred primarily in the caveolin-enriched membrane (CEM) fraction, and the kinetics of PLD1 phosphorylation in the CEM were strongly correlated with PLD1 phosphorylation in the total membrane. Interestingly, EGF-induced PLD1 phosphorylation and activation and the coimmunoprecipitation of PLD1 with caveolin-1 and the EGF receptor in the CEM were significantly attenuated in the palmitoylation-deficient C240S/C241S mutant, which did not localize to the CEM. Immunocytochemical analysis revealed that wild-type PLD1 colocalized with caveolin-1 and the EGF receptor and that phosphorylated PLD1 was localized exclusively in the plasma membrane, although some PLD1 was also detected in vesicular structures. Transfection of wild-type PLD1 but not of C240S/C241S mutant increased EGF-induced raf-1 translocation to the CEM and ERK phosphorylation. This study shows, for the first time, that EGF-induced PLD1 phosphorylation and activation occur in the CEM and that the correct localization of PLD1 to the CEM via palmitoylation is critical for EGF signaling.
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Affiliation(s)
- Jung Min Han
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
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42
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Patel NA, Yamamoto M, Illingworth P, Mancu D, Mebert K, Chappell DS, Watson JE, Cooper DR. Phosphoinositide 3-kinase mediates protein kinase C beta II mRNA destabilization in rat A10 smooth muscle cell cultures exposed to high glucose. Arch Biochem Biophys 2002; 403:111-20. [PMID: 12061808 DOI: 10.1016/s0003-9861(02)00208-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
High-glucose exposure down-regulates protein kinaseC beta II posttranscriptionally in rat and human vascular smooth muscle cells and contributes to increased cell proliferation. High-glucose-induced mRNA destabilization is specific for PKC beta II mRNA, while PKC beta I and other PKC mRNA are not affected. This study focused on whether glucose metabolism was required. The effect was blocked by cytochalasin B, suggesting a requirement for glucose uptake. Glucosamine did not mimic the effect, indicating that metabolism via hexosamine pathway was not involved. The effect was hexokinase-independent since 3-O-methylglucose, in a dose-dependent manner, mimicked high-glucose effects. Cycloheximide did not block the effect excluding dependency on new protein synthesis. Wortmannin and LY294002, phosphoinositide 3-kinase (PI3-kinase) inhibitors, blocked glucose effects in the presence of 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole. Glucose and 3-O-methylglucose activated PI3-kinase, and LY294002 blocked glucose effects on Akt phosphorylation. In these cells, high-glucose concentrations activated a metabolically linked signaling pathway independent of glucose metabolism to regulate mRNA processing.
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Affiliation(s)
- Niketa A Patel
- Department of Biochemistry, College of Medicine, University of South Florida, Tampa, USA
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43
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Meacci E, Becciolini L, Nuti F, Donati C, Cencetti F, Farnararo M, Bruni P. A role for calcium in sphingosine 1-phosphate-induced phospholipase D activity in C2C12 myoblasts. FEBS Lett 2002; 521:200-4. [PMID: 12067705 DOI: 10.1016/s0014-5793(02)02866-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Receptor-regulated phospholipase D (PLD) is a key signaling pathway implicated in the control of fundamental biological processes. Here evidence is presented that in addition to protein kinase C (PKC) and Rho GTPases, Ca(2+) response evoked by sphingosine 1-phosphate (S1P) also participates to the enzyme regulation. Ca(2+) was found critical for PKC(alpha)-mediated PLD activation. Moreover, S1P-induced PLD activity resulted diminished by calmodulin inhibitors such as W-7 and CGS9343B implicating its involvement in the process. A plausible candidate for Ca(2+)-dependent PLD regulation by S1P was represented by calcineurin, in view of the observed reduction of the stimulatory effect by cyclosporin A. In contrast, monomeric GTP-binding protein Ral was translocated to membranes by S1P in a Ca(2+)-independent manner, ruling out its possible role in agonist-mediated regulation of PLD.
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Affiliation(s)
- Elisabetta Meacci
- Dipartimento di Scienze Biochimiche, Università di Firenze, Viale G.B. Morgagni 50, 50134 Firenze, Italy
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44
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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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45
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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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Murphy GA, Graham SM, Morita S, Reks SE, Rogers-Graham K, Vojtek A, Kelley GG, Der CJ. Involvement of phosphatidylinositol 3-kinase, but not RalGDS, in TC21/R-Ras2-mediated transformation. J Biol Chem 2002; 277:9966-75. [PMID: 11788587 DOI: 10.1074/jbc.m109059200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Oncogenic Ras and activated forms of the Ras-related protein TC21/R-Ras2 share similar abilities to alter cell proliferation. However, in contrast to Ras, we found previously that TC21 fails to activate the Raf-1 serine/threonine kinase. Thus, TC21 must utilize non-Raf effectors to regulate cell function. In this study, we determined that TC21 interacts strongly with some (RalGDS, RGL, RGL2/Rlf, AF6, and the phosphatidylinositol 3-kinase (PI3K) catalytic subunit p110delta), and weakly with other Ras small middle dotGTP-binding proteins. In addition, library screening identified novel TC21-interacting proteins. We also determined that TC21, similar to Ras, mediates activation of phospholipase Cepsilon. We then examined if RalGDS, a RalA guanine nucleotide exchange factor, or PI3K are effectors for TC21-mediated signaling and cell proliferation in murine fibroblasts. We found that overexpression of full-length RalGDS reduced the focus forming activity of activated TC21. Furthermore, expression of activated Ras, but not TC21, enhanced GTP loading on RalA. In fact, TC21 attenuated insulin-stimulated RalA small middle dotGTP formation. In contrast, like Ras, expression of activated TC21 resulted in membrane translocation and an increase in the PI3K-dependent phosphorylation of Akt, and inhibition of PI3K activity interfered with TC21 focus formation. Finally, unlike Ras, TC21 did not activate the Rac small GTPase, indicating that Ras may not activate Rac by PI3K. Taken together, these results suggest that PI3K, but not RalGDS, is an important mediator of cell proliferation by TC21.
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Affiliation(s)
- Gretchen A Murphy
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295, USA.
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Schmidt M, Evellin S, Weernink PA, von Dorp F, Rehmann H, Lomasney JW, Jakobs KH. A new phospholipase-C-calcium signalling pathway mediated by cyclic AMP and a Rap GTPase. Nat Cell Biol 2001; 3:1020-4. [PMID: 11715024 DOI: 10.1038/ncb1101-1020] [Citation(s) in RCA: 260] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Stimulation of phosphoinositide-hydrolysing phospholipase C (PLC) generating inositol-1,4,5-trisphosphate is a major calcium signalling pathway used by a wide variety of membrane receptors, activating distinct PLC-beta or PLC-gamma isoforms. Here we report a new PLC and calcium signalling pathway that is triggered by cyclic AMP (cAMP) and mediated by a small GTPase of the Rap family. Activation of the adenylyl cyclase-coupled beta2-adrenoceptor expressed in HEK-293 cells or the endogenous receptor for prostaglandin E1 in N1E-115 neuroblastoma cells induced calcium mobilization and PLC stimulation, seemingly caused by cAMP formation, but was independent of protein kinase A (PKA). We provide evidence that these receptor responses are mediated by a Rap GTPase, specifically Rap2B, activated by a guanine-nucleotide-exchange factor (Epac) regulated by cAMP, and involve the recently identified PLC-epsilon isoform.
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Affiliation(s)
- M Schmidt
- Institut für Pharmakologie, Universitätsklinikum Essen, 45122 Essen, Germany.
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Mwanjewe J, Spitaler M, Ebner M, Windegger M, Geiger M, Kampfer S, Hofmann J, Uberall F, Grunicke HH. Regulation of phospholipase D isoenzymes by transforming Ras and atypical protein kinase C-iota. Biochem J 2001; 359:211-7. [PMID: 11563985 PMCID: PMC1222137 DOI: 10.1042/0264-6021:3590211] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The activation of phospholipase D (PLD) by transforming Ras is well documented. Although two distinct PLD isoforms, PLD1 and PLD2, have been cloned from mammalian cells, it has remained unclear whether both isoenzymes are activated by Ras and, if this is the case, whether they are stimulated by a common mechanism. In the present study we show that expression of transforming Ras in HC11 mouse mammary epithelial cells enhanced the activity of endogenous PLD. Co-expression of Ras with either PLD1b or PLD2 resulted in elevated activities of both PLD isoenzymes in HC11 cells, indicating that transforming Ras was capable of activating both PLD isoforms in vivo. Ras-induced activation of PLD was resistant to the protein kinase C (PKC) inhibitor GF109203X, which preferentially affects conventional- and novel-type PKCs, but sensitive to Ro-31-8220, which inhibits atypical PKCs more effectively. Co-transfection of atypical PKC-iota with either PLD1b or PLD2 led to a selective activation of PLD2 by PKC-iota, whereas PLD1b was not affected. PLD1b, however, was found to be a potent activator of PKC-iota, whereas PLD2 was less effective in this respect. The data suggest that PKC-iota acts upstream of PLD2 and that PLD1b is implicated in the activation of PKC-iota. The data are discussed as indicating a putative signalling cascade comprising Ras-->PLD1b-->PKC-iota-->PLD2. Evidence for the implication of this pathway in the transcriptional regulation of cyclin D1 is also presented.
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Affiliation(s)
- J Mwanjewe
- Institute of Medical Chemistry and Biochemistry, University of Innsbruck, Fritz-Pregl-Strasse 3/VI, A-6020 Innsbruck, Austria
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Oprins JC, van der Burg C, Meijer HP, Munnik T, Groot JA. PLD pathway involved in carbachol-induced Cl- secretion: possible role of TNF-alpha. Am J Physiol Cell Physiol 2001; 280:C789-95. [PMID: 11245595 DOI: 10.1152/ajpcell.2001.280.4.c789] [Citation(s) in RCA: 16] [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
In a previous study, it was found that exposure to tumor necrosis factor-alpha (TNF-alpha) potentiated the electrophysiological response to carbachol in a time-dependent and cycloheximide-sensitive manner. It was deduced that the potentiation could be due to protein kinase C activity because of increased 1,2-diacylglycerol. It was also observed that propranolol could decrease the electrophysiological response to carbachol (Oprins JC, Meijer HP, and Groot JA. Am J Physiol Cell Physiol 278: C463-C472, 2000). The aim of the present study was to investigate whether the phospholipase D (PLD) pathway plays a role in the carbachol response and the potentiating effect of TNF-alpha. The transphosphatidylation reaction in the presence of the primary alcohol 1-butanol [leading to stable phosphatidylbutanol (Pbut) formation] was used to measure activity of PLD. The phosphatidic acid (PA) levels were also measured. Muscarinic stimulation resulted in an increased formation of Pbut and PA. TNF-alpha decreased levels of PA.
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Affiliation(s)
- J C Oprins
- Swammerdam Institute for Life Sciences, University of Amsterdam, P.O. Box 94084, 1090 GB Amsterdam, The Netherlands.
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