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Bowling FZ, Frohman MA, Airola MV. Structure and regulation of human phospholipase D. Adv Biol Regul 2021; 79:100783. [PMID: 33495125 DOI: 10.1016/j.jbior.2020.100783] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/22/2020] [Accepted: 12/28/2020] [Indexed: 12/13/2022]
Abstract
Mammalian phospholipase D (PLD) generates phosphatidic acid, a dynamic lipid secondary messenger involved with a broad spectrum of cellular functions including but not limited to metabolism, migration, and exocytosis. As a promising pharmaceutical target, the biochemical properties of PLD have been well characterized. This has led to the recent crystal structures of human PLD1 and PLD2, the development of PLD specific pharmacological inhibitors, and the identification of cellular regulators of PLD. In this review, we discuss the PLD1 and PLD2 structures, PLD inhibition by small molecules, and the regulation of PLD activity by effector proteins and lipids.
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Affiliation(s)
- Forrest Z Bowling
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA
| | - Michael A Frohman
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA
| | - Michael V Airola
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA.
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2
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Kolesnikov YS, Nokhrina KP, Kretynin SV, Volotovski ID, Martinec J, Romanov GA, Kravets VS. Molecular structure of phospholipase D and regulatory mechanisms of its activity in plant and animal cells. BIOCHEMISTRY (MOSCOW) 2012; 77:1-14. [DOI: 10.1134/s0006297912010014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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Garg R, Peddada N, Sagar A, Nihalani D, Ashish. Visual insight into how low pH alone can induce actin-severing ability in gelsolin under calcium-free conditions. J Biol Chem 2011; 286:20387-97. [PMID: 21498516 PMCID: PMC3121526 DOI: 10.1074/jbc.m111.236943] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/07/2011] [Indexed: 01/17/2023] Open
Abstract
Gelsolin is a key actin cytoskeleton-modulating protein primarily regulated by calcium and phosphoinositides. In addition, low pH has also been suggested to activate gelsolin in the absence of Ca(2+) ions, although no structural insight on this pathway is available except for a reported decrement in its diffusion coefficient at low pH. We also observed ~1.6-fold decrease in the molecular mobility of recombinant gelsolin when buffer pH was lowered from 9 to 5. Analysis of the small angle x-ray scattering data collected over the same pH range indicated that the radius of gyration and maximum linear dimension of gelsolin molecules increased from 30.3 to 34.1 Å and from 100 to 125 Å, respectively. Models generated for each dataset indicated that similar to the Ca(2+)-induced process, low pH also promotes unwinding of this six-domain protein but only partially. It appeared that pH is able to induce extension of the G1 domain from the rest of the five domains, whereas the Ca(2+)-sensitive latch between G2 and G6 domains remains closed. Interestingly, increasing the free Ca(2+) level to merely ~40 nM, the partially open pH 5 shape "sprung open" to a shape seen earlier for this protein at pH 8 and 1 mm free Ca(2+). Also, pH alone could induce a shape where the g3-g4 linker of gelsolin was open when we truncated the C-tail latch from this protein. Our results provide insight into how under physiological conditions, a drop in pH can fully activate the F-actin-severing shape of gelsolin with micromolar levels of Ca(2+) available.
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Affiliation(s)
- Renu Garg
- the Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, 160036, India
| | - Nagesh Peddada
- the Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, 160036, India
| | - Amin Sagar
- the Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, 160036, India
| | - Deepak Nihalani
- From the Renal, Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Ashish
- the Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, 160036, India
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Jeon H, Kwak D, Noh J, Lee MN, Lee CS, Suh PG, Ryu SH. Phospholipase D2 induces stress fiber formation through mediating nucleotide exchange for RhoA. Cell Signal 2011; 23:1320-6. [PMID: 21440060 DOI: 10.1016/j.cellsig.2011.03.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 03/15/2011] [Indexed: 12/23/2022]
Abstract
Phospholipase D (PLD) is involved in diverse cellular processes including cell movement, adhesion, and vesicle trafficking through cytoskeletal rearrangements. However, the mechanism by which PLD induces cytoskeletal reorganization is still not fully understood. Here, we describe a new link to cytoskeletal changes that is mediated by PLD2 through direct nucleotide exchange on RhoA. We found that PLD2 induces RhoA activation independent of its lipase activity. PLD2 directly interacted with RhoA, and the PX domain of PLD2 specifically recognized nucleotide-free RhoA. Finally, we found that the PX domain of PLD2 has guanine nucleotide-exchange factor (GEF) activity for RhoA in vitro. In addition, we verified that overexpression of the PLD2-PX domain induces RhoA activation, thereby provoking stress fiber formation. Together, our findings suggest that PLD2 functions as an upstream regulator of RhoA, which enables us to understand how PLD2 regulates cytoskeletal reorganization in a lipase activity-independent manner.
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Affiliation(s)
- Hyeona Jeon
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, South Korea
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Li GH, Arora PD, Chen Y, McCulloch CA, Liu P. Multifunctional roles of gelsolin in health and diseases. Med Res Rev 2010; 32:999-1025. [PMID: 22886630 DOI: 10.1002/med.20231] [Citation(s) in RCA: 175] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Gelsolin, a Ca(2+) -regulated actin filament severing, capping, and nucleating protein, is an ubiquitous, multifunctional regulator of cell structure and metabolism. More recent data show that gelsolin can act as a transcriptional cofactor in signal transduction and its own expression and function can be influenced by epigenetic changes. Here, we review the functions of the plasma and cytoplasmic forms of gelsolin, and their manifold impacts on cancer, apoptosis, infection and inflammation, cardiac injury, pulmonary diseases, and aging. An improved understanding of the functions and regulatory mechanisms of gelsolin may lead to new considerations of this protein as a potential biomarker and/or therapeutic target.
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Affiliation(s)
- Guo Hua Li
- Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
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Finkelstein M, Etkovitz N, Breitbart H. Role and regulation of sperm gelsolin prior to fertilization. J Biol Chem 2010; 285:39702-9. [PMID: 20937821 DOI: 10.1074/jbc.m110.170951] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To acquire fertilization competence, spermatozoa should undergo several biochemical changes in the female reproductive tract, known as capacitation. The capacitated spermatozoon can interact with the egg zona pellucida resulting in the occurrence of the acrosome reaction, a process that allowed its penetration into the egg and fertilization. Sperm capacitation requires actin polymerization, whereas F-actin must disperse prior to the acrosome reaction. Here, we suggest that the actin-severing protein, gelsolin, is inactive during capacitation and is activated prior to the acrosome reaction. The release of bound gelsolin from phosphatidylinositol 4,5-bisphosphate (PIP(2)) by PBP10, a peptide containing the PIP(2)-binding domain of gelsolin, or by activation of phospholipase C, which hydrolyzes PIP(2), caused rapid Ca(2+)-dependent F-actin depolymerization as well as enhanced acrosome reaction. Using immunoprecipitation assays, we showed that the tyrosine kinase SRC and gelsolin coimmunoprecipitate, and activating SRC by adding 8-bromo-cAMP (8-Br-cAMP) enhanced the amount of gelsolin in this precipitate. Moreover, 8-Br-cAMP enhanced tyrosine phosphorylation of gelsolin and its binding to PIP(2(4,5)), both of which inactivated gelsolin, allowing actin polymerization during capacitation. This actin polymerization was blocked by inhibiting the Src family kinases, suggesting that gelsolin is activated under these conditions. These results are further supported by our finding that PBP10 was unable to cause complete F-actin breakdown in the presence of 8-Br-cAMP or vanadate. In conclusion, inactivation of gelsolin during capacitation occurs by its binding to PIP(2) and tyrosine phosphorylation by SRC. The release of gelsolin from PIP(2) together with its dephosphorylation enables gelsolin activation, resulting in the acrosome reaction.
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Affiliation(s)
- Maya Finkelstein
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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Saarikangas J, Zhao H, Lappalainen P. Regulation of the actin cytoskeleton-plasma membrane interplay by phosphoinositides. Physiol Rev 2010; 90:259-89. [PMID: 20086078 DOI: 10.1152/physrev.00036.2009] [Citation(s) in RCA: 362] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The plasma membrane and the underlying cortical actin cytoskeleton undergo continuous dynamic interplay that is responsible for many essential aspects of cell physiology. Polymerization of actin filaments against cellular membranes provides the force for a number of cellular processes such as migration, morphogenesis, and endocytosis. Plasma membrane phosphoinositides (especially phosphatidylinositol bis- and trisphosphates) play a central role in regulating the organization and dynamics of the actin cytoskeleton by acting as platforms for protein recruitment, by triggering signaling cascades, and by directly regulating the activities of actin-binding proteins. Furthermore, a number of actin-associated proteins, such as BAR domain proteins, are capable of directly deforming phosphoinositide-rich membranes to induce plasma membrane protrusions or invaginations. Recent studies have also provided evidence that the actin cytoskeleton-plasma membrane interactions are misregulated in a number of pathological conditions such as cancer and during pathogen invasion. Here, we summarize the wealth of knowledge on how the cortical actin cytoskeleton is regulated by phosphoinositides during various cell biological processes. We also discuss the mechanisms by which interplay between actin dynamics and certain membrane deforming proteins regulate the morphology of the plasma membrane.
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Affiliation(s)
- Juha Saarikangas
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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Kawaji A, Ohnaka Y, Osada S, Nishizuka M, Imagawa M. Gelsolin, an Actin Regulatory Protein, is Required for Differentiation of Mouse 3T3-L1 Cells into Adipocytes. Biol Pharm Bull 2010; 33:773-9. [DOI: 10.1248/bpb.33.773] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Atsuko Kawaji
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Yuki Ohnaka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Shigehiro Osada
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Makoto Nishizuka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Masayoshi Imagawa
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
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10
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Cockcroft S. Phosphatidic acid regulation of phosphatidylinositol 4-phosphate 5-kinases. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:905-12. [PMID: 19298865 DOI: 10.1016/j.bbalip.2009.03.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 11/18/2022]
Abstract
Phosphatidic acid (PA) production by receptor-stimulated phospholipase D is believed to play an important role in the regulation of cell function. The second messenger function of PA remains to be elucidated. PA can bind and affect the activities of different enzymes and here we summarise the current status of activation of Type I phosphatidylinositol 4-phosphate 5-kinase by PA. Type 1 phosphatidylinositol 4-phosphate 5-kinase is also regulated by ARF proteins as is phospholipase D and we discuss the contributions of ARF and PA towards phosphatidylinositol(4,5)bisphosphate synthesis at the plasma membrane.
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Affiliation(s)
- Shamshad Cockcroft
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
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Méré J, Chahinian A, Maciver S, Fattoum A, Bettache N, Benyamin Y, Roustan C. Gelsolin binds to polyphosphoinositide-free lipid vesicles and simultaneously to actin microfilaments. Biochem J 2005; 386:47-56. [PMID: 15527423 PMCID: PMC1134765 DOI: 10.1042/bj20041054] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gelsolin is a calcium-, pH- and lipid-dependent actin filament severing/capping protein whose main function is to regulate the assembly state of the actin cytoskeleton. Gelsolin is associated with membranes in cells, and it is generally assumed that this interaction is mediated by PPIs (polyphosphoinositides), since an interaction with these lipids has been characterized in vitro. We demonstrate that non-PPI lipids also bind gelsolin, especially at low pH. The data suggest further that gelsolin becomes partially buried in the lipid bilayer under mildly acidic conditions, in a manner that is not dependent of the presence of PPIs. Our data also suggest that lipid binding involves a number of sites that are spread throughout the gelsolin molecule. Linker regions between gelsolin domains have been implicated by other work, notably the linker between G1 and G2 (gelsolin domains 1 and 2 respectively), and we postulate that the linker region between the N-terminal and C-terminal halves of gelsolin (between G3 and G4) is also involved in the interaction with lipids. This region is compatible with other studies in which additional binding sites have been located within G4-6. The lipid-gelsolin interactions reported in the present paper are not calcium-dependent, and are likely to involve significant conformational changes to the gelsolin molecule, as the chymotryptic digest pattern is altered by the presence of lipids under our conditions. We also report that vesicle-bound gelsolin is capable of binding to actin filaments, presumably through barbed end capping. Gelsolin bound to vesicles can nucleate actin assembly, but is less active in severing microfilaments.
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Affiliation(s)
- Jocelyn Méré
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Anne Chahinian
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Sutherland K. Maciver
- †School of Biomedical and Clinical Laboratory Sciences, Division of Biomedical Sciences, College of Medicine, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland, U.K
| | - Abdellatif Fattoum
- ‡Centre de Recherches de Biochimie Macromoléculaire, FRE 2593 (CNRS), 1919 rte de Mende, 34293 Montpellier Cedex 5, France
| | - Nadir Bettache
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Yves Benyamin
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Claude Roustan
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
- To whom correspondence should be addressed (email )
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Chae YC, Lee S, Lee HY, Heo K, Kim JH, Kim JH, Suh PG, Ryu SH. Inhibition of Muscarinic Receptor-linked Phospholipase D Activation by Association with Tubulin. J Biol Chem 2005; 280:3723-30. [PMID: 15548524 DOI: 10.1074/jbc.m406987200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian phospholipase D (PLD) is considered a key enzyme in the transmission signals from various receptors including muscarinic receptors. PLD activation is a rapid and transient process, but a negative regulator has not been found that inhibits signal-dependent PLD activation. Here, for the first time, we report that tubulin binding to PLD2 is an inhibition mechanism for muscarinic receptor-linked PLD2 activation. Tubulin was identified in an immunoprecipitated PLD2 complex from COS-7 cells by peptide mass fingerprinting. The direct interaction between PLD2 and tubulin was found to be mediated by a specific region of PLD2 (amino acids 476-612). PLD2 was potently inhibited (IC50 <10 nM) by tubulin binding in vitro. In cells, the interaction between PLD2 and tubulin was increased by the microtubule disrupting agent nocodazole and reduced by the microtubule stabilizing agent Taxol. Moreover, PLD2 activity was found to be inversely correlated with the level of monomeric tubulin. In addition, we found that interaction with and the inhibition of PLD2 by monomeric tubulin is important for the muscarinic receptor-linked PLD signaling pathway. Interaction between PLD2 and tubulin was increased only after 1-2 min of carbachol stimulation when carbachol-stimulated PLD2 activity was decreased. The expression of the tubulin binding region of PLD2 blocked the later decrease in carbachol-induced PLD activity by masking tubulin binding. Taken together, these results indicate that an increase in local membrane monomeric tubulin concentration inhibits PLD2 activity, and provides a novel mechanism for the inhibition of muscarinic receptor-induced PLD2 activation by interaction with tubulin.
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Affiliation(s)
- Young Chan Chae
- Division of Molecular and Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
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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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Lee HY, Park JB, Jang IH, Chae YC, Kim JH, Kim IS, Suh PG, Ryu SH. Munc-18-1 Inhibits Phospholipase D Activity by Direct Interaction in an Epidermal Growth Factor-reversible Manner. J Biol Chem 2004; 279:16339-48. [PMID: 14744865 DOI: 10.1074/jbc.m310976200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian phospholipase D (PLD) has been reported to be a key enzyme for epidermal growth factor (EGF)-induced cellular signaling, however, the regulatory mechanism of PLD is still unclear. In this report, we found that Munc-18-1 is a potent negative regulator of PLD in the basal state and that its inhibition is abolished by EGF stimulation. We investigated PLD-binding proteins obtained from rat brain extract, and identified a 67-kDa protein as Munc-18-1 by peptide-mass finger-printing. The direct association between PLD and Munc-18-1 was confirmed by in vitro binding analysis using the purified proteins, and their binding sites were identified as the phox homology domain of PLD and multiple sites of Munc-18-1. PLD activity was potently inhibited by Munc-18-1 in vitro (IC50 = 2-5 nm), and the cotransfection of COS-7 cells with Munc-18-1 and PLD inhibited basal PLD activity in vivo. In the basal state, Munc-18-1 coprecipitated with PLD and colocalized with PLD2 at the plasma membrane of COS-7 cells. EGF treatment triggered the dissociation of Munc-18-1 from PLD when PLD was activated by EGF. The dissociation of the endogenous interaction between Munc-18-1 and PLD, and the activation of PLD by EGF were also observed in primary cultured chromaffin cells. These results suggest that Munc-18-1 is a potent negative regulator of basal PLD activity and that EGF stimulation abolishes this interaction.
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Affiliation(s)
- Hye Young Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784 Republic of Korea
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Tomás M, Lázaro-Diéguez F, Durán JM, Marín P, Renau-Piqueras J, Egea G. Protective effects of lysophosphatidic acid (LPA) on chronic ethanol-induced injuries to the cytoskeleton and on glucose uptake in rat astrocytes. J Neurochem 2003; 87:220-9. [PMID: 12969268 DOI: 10.1046/j.1471-4159.2003.01993.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Ethanol induces severe alterations in membrane trafficking in hepatocytes and astrocytes, the molecular basis of which is unclear. One of the main candidates is the cytoskeleton and the molecular components that regulate its organization and dynamics. Here, we examine the effect of chronic exposure to ethanol on the organization and dynamics of actin and microtubule cytoskeletons and glucose uptake in rat astrocytes. Ethanol-treated cells cultured in either the presence or absence of fetal calf serum showed a significant increase in 2-deoxyglucose uptake. Ethanol also caused alterations in actin organization, consisting of the dissolution of stress fibres and the appearance of circular filaments beneath the plasma membrane. When lysophosphatidic acid (LPA), which is a normal constituent of serum and a potent intercellular lipid mediator with growth factor and actin rearrangement activities, was added to ethanol-treated astrocytes cultured without fetal calf serum, it induced the re-appearance of actin stress fibres and the normalization of 2-deoxyglucose uptake. Furthermore, ethanol also perturbed the microtubule dynamics, which delayed the recovery of the normal microtubule organization following removal of the microtubule-disrupting agent nocodazole. Again, pre-treatment with LPA prevented this alteration. Ethanol-treated rodent fibroblast NIH3T3 cells that constitutively express an activated Rho mutant protein (GTP-bound form) were insensitive to ethanol, as they showed no alteration either in actin stress-fibre organization or in 2-deoxyglucose uptake. We discuss the putative signalling targets by which ethanol could alter the cytoskeleton and hexose uptake and the cytoprotective effect of LPA against ethanol-induced damages. The latter opens the possibility that LPA or a similar non-hydrolysable lipid derivative could be used as a cytoprotective agent against the noxious effects of ethanol.
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Affiliation(s)
- Mónica Tomás
- Centro de Investigación, Hospital La Fe, Valencia, Spain
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Lagarrigue E, Ternent D, Maciver SK, Fattoum A, Benyamin Y, Roustan C. The activation of gelsolin by low pH. ACTA ACUST UNITED AC 2003; 270:4105-12. [PMID: 14519122 DOI: 10.1046/j.1432-1033.2003.03803.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Gelsolin is a multidomain and multifunction protein that nucleates the assembly of filaments and severs them. The activation of gelsolin by calcium is a multistep process involving many calcium binding sites that act to unfold the molecule from a tight structure to a more loose form in which three actin-binding sites become exposed. Low pH is also known to activate gelsolin, in the absence of calcium and this too results in an unfolding of the molecule. Less is known how pH-activation occurs but we show that there are significant differences in the mechanisms that lead to activation. Crucially, while it is known that the bonds between G2 and G6 are broken by co-operative occupancy of calcium binding sites in both domains [Lagarrique, E., Maciver, S. K., Fattoum, A., Benyamin, Y. & Roustan, C. (2003) Eur. J. Biochem. 270, 2236-2243.], pH values that activate gelsolin do not result in a weakening of the G2-G6 bonds. We report the existence of pH-dependent conformational changes within G2 and in G4-6 that differ from those induced by calcium, and that low pH overrides the requirement for calcium for actin-binding within G4-6 to a modest extent so that a Kd of 1 micro m is measured, compared to 30-40 nm in the presence of calcium. Whereas the pH-dependent conformational change in G2 is possibly different from the change induced by calcium, the changes measured in G4-6 appear to be similar in both calcium and low pH.
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Affiliation(s)
- Emeline Lagarrigue
- UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Montpellier Cedex 5, France
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Kusner DJ, Barton JA, Wen KK, Wang X, Rubenstein PA, Iyer SS. Regulation of phospholipase D activity by actin. Actin exerts bidirectional modulation of Mammalian phospholipase D activity in a polymerization-dependent, isoform-specific manner. J Biol Chem 2002; 277:50683-92. [PMID: 12388543 DOI: 10.1074/jbc.m209221200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many critical cellular processes, including proliferation, vesicle trafficking, and secretion, are regulated by both phospholipase D (PLD) and the actin microfilament system. Stimulation of human PLD1 results in its association with the detergent-insoluble actin cytoskeleton, but the molecular mechanisms and functional consequences of PLD-actin interactions remain incompletely defined. Biochemical and pharmacologic modulation of actin polymerization resulted in complex bidirectional effects on PLD activity, both in vitro and in vivo. Highly purified G-actin inhibited basal and stimulated PLD activity, whereas F-actin produced the opposite effects. Actin-induced modulation of PLD activity was independent of the activating stimulus. The efficacy and potency of the effects of actin were isoform-specific but broadly conserved among actin family members. Human betagamma-actin was only 45% as potent and 40% as efficacious as rabbit skeletal muscle alpha-actin, whereas its inhibitory profile was similar to the single actin species from the yeast, Saccharomyces cerevisiae. Use of actin polymerization-specific reagents indicated that PLD1 binds both monomeric G-actin, as well as actin filaments. These data are consistent with a model in which the physical state of the actin cytoskeleton is a critical determinant of its regulation of PLD activity.
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Affiliation(s)
- David J Kusner
- Department of Internal Medicine, Division of Infectious Diseases, Inflammation Program, University of Iowa and Veterans Affairs Medical Center, Iowa City, Iowa 52242, USA.
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De Corte V, Bruyneel E, Boucherie C, Mareel M, Vandekerckhove J, Gettemans J. Gelsolin-induced epithelial cell invasion is dependent on Ras-Rac signaling. EMBO J 2002; 21:6781-90. [PMID: 12485999 PMCID: PMC139100 DOI: 10.1093/emboj/cdf680] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2002] [Revised: 10/25/2002] [Accepted: 10/29/2002] [Indexed: 12/26/2022] Open
Abstract
Gelsolin is a widely distributed actin binding protein involved in controlling cell morphology, motility, signaling and apoptosis. The role of gelsolin in tumor progression, however, remains poorly understood. Here we show that expression of green fluorescent protein (GFP)-tagged gelsolin in MDCK-AZ, MDCKtsSrc or HEK293T cells promotes invasion into collagen type I. In organ culture assays, MDCK cells expressing gelsolin-GFP invaded pre-cultured chick heart fragments. Gelsolin expression inhibited E-cadherin-mediated cell aggregation but did not disrupt the E-cadherin-catenin complex. Co-expression of dominant-negative Rac1N17, but not RhoAN19 or Cdc42N17, counteracted gelsolin-induced invasion, suggesting a requirement for Rac1 activity. Increased ARF6, PLD or PIP5K 1alpha activity canceled out gelsolin-induced invasion. Furthermore, we found that invasion induced by gelsolin is dependent on Ras activity, acting through the PI3K-Rac pathway via the Ras guanine nucleotide exchange factor Sos-1. These findings establish a connection between gelsolin and the Ras oncogenic signaling pathway.
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Affiliation(s)
| | - Erik Bruyneel
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Rommelaere Institute, Albert Baertsoenkaai 3, B-9000 Gent, Belgium and Flanders Interuniversity Institute for Biotechnology (V.I.B.) and
Laboratory of Experimental Cancerology, Department of Radiotherapy and Nuclear Medicine, Ghent University Hospital (1P7), De Pintelaan 185, B-9000 Ghent, Belgium Corresponding author e-mail:
| | | | - Marc Mareel
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Rommelaere Institute, Albert Baertsoenkaai 3, B-9000 Gent, Belgium and Flanders Interuniversity Institute for Biotechnology (V.I.B.) and
Laboratory of Experimental Cancerology, Department of Radiotherapy and Nuclear Medicine, Ghent University Hospital (1P7), De Pintelaan 185, B-9000 Ghent, Belgium Corresponding author e-mail:
| | | | - Jan Gettemans
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Rommelaere Institute, Albert Baertsoenkaai 3, B-9000 Gent, Belgium and Flanders Interuniversity Institute for Biotechnology (V.I.B.) and
Laboratory of Experimental Cancerology, Department of Radiotherapy and Nuclear Medicine, Ghent University Hospital (1P7), De Pintelaan 185, B-9000 Ghent, Belgium Corresponding author e-mail:
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O'Luanaigh N, Pardo R, Fensome A, Allen-Baume V, Jones D, Holt MR, Cockcroft S. Continual production of phosphatidic acid by phospholipase D is essential for antigen-stimulated membrane ruffling in cultured mast cells. Mol Biol Cell 2002; 13:3730-46. [PMID: 12388770 PMCID: PMC129979 DOI: 10.1091/mbc.e02-04-0213] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Phospholipase Ds (PLDs) are regulated enzymes that generate phosphatidic acid (PA), a putative second messenger implicated in the regulation of vesicular trafficking and cytoskeletal reorganization. Mast cells, when stimulated with antigen, show a dramatic alteration in their cytoskeleton and also release their secretory granules by exocytosis. Butan-1-ol, which diverts the production of PA generated by PLD to the corresponding phosphatidylalcohol, was found to inhibit membrane ruffling when added together with antigen or when added after antigen. Inhibition by butan-1-ol was completely reversible because removal of butan-1-ol restored membrane ruffling. Measurements of PLD activation by antigen indicate a requirement for continual PA production during membrane ruffling, which was maintained for at least 30 min. PLD1 and PLD2 are both expressed in mast cells and green fluorescent protein-tagged proteins were used to identify PLD2 localizing to membrane ruffles of antigen-stimulated mast cells together with endogenous ADP ribosylation factor 6 (ARF6). In contrast, green fluorescent protein-PLD1 localized to intracellular vesicles and remained in this location after stimulation with antigen. Membrane ruffling was independent of exocytosis of secretory granules because phorbol 12-myristate 13-acetate increased membrane ruffling in the absence of exocytosis. Antigen or phorbol 12-myristate 13-acetate stimulation increased both PLD1 and PLD2 activity when expressed individually in RBL-2H3 cells. Although basal activity of PLD2-overexpressing cells is very high, membrane ruffling was still dependent on antigen stimulation. In permeabilized cells, antigen-stimulated phosphatidylinositol(4,5)bisphosphate synthesis was dependent on both ARF6 and PA generated from PLD. We conclude that both activation of ARF6 by antigen and a continual PLD2 activity are essential for local phosphatidylinositol(4,5)bisphosphate generation that regulates dynamic actin cytoskeletal rearrangements.
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Affiliation(s)
- Niamh O'Luanaigh
- Department of Physiology, University College London, London WC1E 6JJ, United Kingdom
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20
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Dong Y, Asch HL, Ying A, Asch BB. Molecular mechanism of transcriptional repression of gelsolin in human breast cancer cells. Exp Cell Res 2002; 276:328-36. [PMID: 12027462 DOI: 10.1006/excr.2002.5534] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Loss of gelsolin, a tumor suppressor, is one of the most frequently occurring molecular defects in breast cancers of diverse etiologies and across at least three animal species: human, mouse, and rat. Our previous analysis of breast cancer cells demonstrated that the deficiency is not due to mutation of the gelsolin gene, but instead to epigenetic factors, including decreased transcription of the gene. The study described herein provides the first functional characterization of the human gelsolin promoter and reveals a mechanistic basis for the reduced gelsolin transcription. In reporter gene assays, the gelsolin promoter was less active in low-gelsolin-expressing breast cancer cells. A cis-element mediating this reduced promoter activity was defined as a 27-bp sequence located approximately 135 bp upstream of the transcription start site. Gel shift and supershift assays and Southwestern blotting analysis indicated that activating transcription factor-1 (ATF-1) and a protein of approximately 100 kDa may have cancer cell-specific DNA-binding activity to the 27-bp gelsolin cis-element. Although the ATF-1 protein was highly expressed in both benign and tumorigenic breast cells, its DNA-binding activity was selectively abundant in the cancer cells and correlated inversely with the gelsolin mRNA level. Thus, our results suggest a role for ATF-1 in gelsolin promoter silencing in contrast to its transactivating effect on various other promoters.
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Affiliation(s)
- Yan Dong
- Division of Experimental Pathology, Roswell Park Cancer Institute (RPCI), Buffalo, New York 14263, USA
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21
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Defacque H, Bos E, Garvalov B, Barret C, Roy C, Mangeat P, Shin HW, Rybin V, Griffiths G. Phosphoinositides regulate membrane-dependent actin assembly by latex bead phagosomes. Mol Biol Cell 2002; 13:1190-202. [PMID: 11950931 PMCID: PMC102261 DOI: 10.1091/mbc.01-06-0314] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Actin assembly on membrane surfaces is an elusive process in which several phosphoinositides (PIPs) have been implicated. We have reconstituted actin assembly using a defined membrane surface, the latex bead phagosome (LBP), and shown that the PI(4,5)P(2)-binding proteins ezrin and/or moesin were essential for this process (). Here, we provide several lines of evidence that both preexisting and newly synthesized PI(4,5)P(2), and probably PI(4)P, are essential for phagosomal actin assembly; only these PIPs were routinely synthesized from ATP during in vitro actin assembly. Treatment of LBP with phospholipase C or with adenosine, an inhibitor of type II PI 4-kinase, as well as preincubation with anti-PI(4)P or anti-PI(4,5)P(2) antibodies all inhibited this process. Incorporation of extra PI(4)P or PI(4,5)P(2) into the LBP membrane led to a fivefold increase in the number of phagosomes that assemble actin. An ezrin mutant mutated in the PI(4,5)P(2)-binding sites was less efficient in binding to LBPs and in reconstituting actin assembly than wild-type ezrin. Our data show that PI 4- and PI 5-kinase, and under some conditions also PI 3-kinase, activities are present on LBPs and can be activated by ATP, even in the absence of GTP or cytosolic components. However, PI 3-kinase activity is not required for actin assembly, because the process was not affected by PI 3-kinase inhibitors. We suggest that the ezrin-dependent actin assembly on the LBP membrane may require active turnover of D4 and D5 PIPs on the organelle membrane.
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Affiliation(s)
- Hélène Defacque
- European Molecular Biology Laboratory, 69012 Heidelberg, Germany
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22
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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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23
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Abstract
Tubulin forms the microtubule and regulates certain G-protein-mediated signaling pathways. Both functions rely on the GTP-binding properties of tubulin. Signal transduction through Galpha(q)-regulated phospholipase Cbeta1 (PLCbeta1) is activated by tubulin through a direct transfer of GTP from tubulin to Galpha(q). However, at high tubulin concentrations, inhibition of PLCbeta1 is observed. This report demonstrates that tubulin inhibits PLCbeta1 by binding the PLCbeta1 substrate phosphatidylinositol 4,5-bisphosphate (PIP2). Tubulin binding of PIP2 was specific, because PIP2 but not phosphatidylinositol 3,4,5-trisphosphate, phosphatidylinositol 3-phosphate, phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, or inositol 1,4,5-trisphosphate inhibited microtubule assembly. PIP2 did not affect GTP binding or GTP hydrolysis by tubulin. Muscarinic agonists promoted microtubule depolymerization and translocation of tubulin to the plasma membrane. PIP2 augmented this process in both Sf9 cells, containing a recombinant PLCbeta1 pathway, and SK-N-SH neuroblastoma cells. Colocalization of tubulin and PIP2 at the plasma membrane was demonstrated with confocal laser immunofluorescence microscopy. Although tubulin bound to both Galpha(q) and PLCbeta1, PIP2 facilitated the interaction between tubulin and PLCbeta1 but not that between tubulin and Galpha(q). However, PIP2 did augment formation of tubulin--Galpha(q)-PLCbeta1 complexes. Subsequent to potentiating PLCbeta1 activation, sustained agonist-independent membrane binding of tubulin at PIP2- and PLCbeta1-rich sites appeared to inhibit Galpha(q) coupling to PLCbeta1. Furthermore, colchicine increased membrane-associated tubulin and also inhibited PLCbeta1 activity in SK-N-SH cells. Thus, tubulin, depending on local membrane concentration, may serve as a positive or negative regulator of phosphoinositide hydrolysis. Rapid changes in membrane lipid composition or in the cytoskeleton might modify neuronal signaling through such a mechanism.
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24
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Lee S, Kim JH, Lee CS, Kim JH, Kim Y, Heo K, Ihara Y, Goshima Y, Suh PG, Ryu SH. Collapsin response mediator protein-2 inhibits neuronal phospholipase D(2) activity by direct interaction. J Biol Chem 2002; 277:6542-9. [PMID: 11741937 DOI: 10.1074/jbc.m108047200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the functional significance of neuronal phospholipase D (PLD) is being recognized, little is known about its regulatory role in neuronal cells. To elucidate the regulatory mechanism of neuronal PLD, we investigated PLD(2)-binding neuronal protein from rat brain cytosol. During the fractionation of rat brain cytosol by four-column chromatography, a 62-kDa PLD(2)-interacting protein was detected by PLD(2) overlay assay and identified as collapsin response mediator protein-2 (CRMP-2), which controls neuronal axon guidance and outgrowth. Using bacterially expressed glutathione S-transferase fusion proteins, we found that two regions (amino acids 65-192 (the phagocytic oxidase domain) and 724-825) of PLD(2) and a single region (amino acids 243-300) of CRMP-2 are required for the direct binding of both proteins. A co-immunoprecipitation study in COS-7 cells also showed an in vivo interaction between CRMP-2 and PLD(2). Interestingly, CRMP-2 was found to potently inhibit PLD(2) activity in a concentration-dependent manner (IC(50) = 30 nm). Overexpression studies also showed that CRMP-2 is an in vivo inhibitor of PLD(2) in PC12 cells. Moreover, increasing the concentration of semaphorin 3A, one of the repulsive axon guidance cues, showed that PLD(2) activity can be inhibited in PC12 cells. Immunocytochemistry further revealed that PLD(2) is co-localized with CRMP-2 in the distal tips of neurites, its possible action site, in differentiated PC12 cells. Taken together, our results indicate that CRMP-2 may interact directly with and inhibit neuronal PLD(2), suggesting that this inhibitory mode of regulation may play a role in neuronal pathfinding during the developmental stage.
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Affiliation(s)
- Sukmook Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
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25
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Panebra A, Ma SX, Zhai LW, Wang XT, Rhee SG, Khurana S. Regulation of phospholipase C-gamma(1) by the actin-regulatory protein villin. Am J Physiol Cell Physiol 2001; 281:C1046-58. [PMID: 11502583 DOI: 10.1152/ajpcell.2001.281.3.c1046] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The actin-regulatory protein villin is tyrosine phosphorylated and associates with phospholipase C-gamma(1) (PLC-gamma(1)) in the brush border of intestinal epithelial cells. To study the mechanism of villin-associated PLC-gamma(1) activation, we reconstituted in vitro the tyrosine phosphorylation of villin and its association with PLC-gamma(1). Recombinant villin was phosphorylated in vitro by the nonreceptor tyrosine kinase c-src or by expression in the TKX1 competent cells that carry an inducible tyrosine kinase gene. Using in vitro binding assays, we demonstrated that tyrosine-phosphorylated villin associates with the COOH-terminal Src homology 2 (SH2) domain of PLC-gamma(1). The catalytic activity of PLC-gamma(1) was inhibited by villin in a dose-dependent manner with half-maximal inhibition at a concentration of 12.4 microM. Villin inhibited PLC-gamma(1) activity by sequestering the substrate phosphatidylinositol 4,5-bisphosphate (PIP(2)), since increasing concentrations of PIP(2) reversed the inhibitory effects of villin on PLC activity. The inhibition of PLC-gamma(1) activity by villin was reversed by the tyrosine phosphorylation of villin. Further, we demonstrated that tyrosine phosphorylation of villin abolished villin's ability to associate with PIP(2). In conclusion, tyrosine-phosphorylated villin associates with the COOH-terminal SH2 domain of PLC-gamma(1) and activates PLC-gamma(1) catalytic activity. Villin regulates PLC-gamma(1) activity by modifying its own ability to bind PIP(2). This study provides biochemical proof of the functional relevance of tyrosine phosphorylation of villin and identifies the molecular mechanisms involved in the activation of PLC-gamma(1) by villin.
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Affiliation(s)
- A Panebra
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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26
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Lee S, Park JB, Kim JH, Kim Y, Kim JH, Shin KJ, Lee JS, Ha SH, Suh PG, Ryu SH. Actin Directly Interacts with Phospholipase D, Inhibiting Its Activity. J Biol Chem 2001; 276:28252-60. [PMID: 11373276 DOI: 10.1074/jbc.m008521200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian phospholipase D (PLD) plays a key role in several signal transduction pathways and is involved in many diverse functions. To elucidate the complex molecular regulation of PLD, we investigated PLD-binding proteins obtained from rat brain extract. Here we report that a 43-kDa protein in the rat brain, beta-actin, acts as a major PLD2 direct-binding protein as revealed by peptide mass fingerprinting in combination with matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. We also determined that the region between amino acids 613 and 723 of PLD2 is required for the direct binding of beta-actin, using bacterially expressed glutathione S-transferase fusion proteins of PLD2 fragments. Intriguingly, purified beta-actin potently inhibited both phosphatidylinositol-4,5-bisphosphate- and oleate-dependent PLD2 activities in a concentration-dependent manner (IC50 = 5 nm). In a previous paper, we reported that alpha-actinin inhibited PLD2 activity in an interaction-dependent and an ADP-ribosylation factor 1 (ARF1)-reversible manner (Park, J. B., Kim, J. H., Kim, Y., Ha, S. H., Kim, J. H., Yoo, J.-S., Du, G., Frohman, M. A., Suh, P.-G., and Ryu, S. H. (2000) J. Biol. Chem. 275, 21295-21301). In vitro binding analyses showed that beta-actin could displace alpha-actinin binding to PLD2, demonstrating independent interaction between cytoskeletal proteins and PLD2. Furthermore, ARF1 could steer the PLD2 activity in a positive direction regardless of the inhibitory effect of beta-actin on PLD2. We also observed that beta-actin regulates PLD1 and PLD2 with similar binding and inhibitory potencies. Immunocytochemical and co-immunoprecipitation studies demonstrated the in vivo interaction between the two PLD isozymes and actin in cells. Taken together, these results suggest that the regulation of PLD by cytoskeletal proteins, beta-actin and alpha-actinin, and ARF1 may play an important role in cytoskeleton-related PLD functions.
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Affiliation(s)
- S Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
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27
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Affiliation(s)
- L D Burtnick
- Chemistry Department, University of British Columbia, Vancouver, V6T 1Z1, Canada
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28
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Crowley MR, Head KL, Kwiatkowski DJ, Asch HL, Asch BB. The mouse mammary gland requires the actin-binding protein gelsolin for proper ductal morphogenesis. Dev Biol 2000; 225:407-23. [PMID: 10985859 DOI: 10.1006/dbio.2000.9844] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Gelsolin is an actin-binding/severing protein expressed in intracellular and secreted forms. It is a major regulator of the form and function of the actin cytoskeleton in most all cells. Here we demonstrate that female mice with a targeted deletion of the gelsolin gene (Gsn-/-) have defects in mammary gland morphogenesis. Two distinct defects were identified in the gelsolin-null mammary gland. First, the mammary anlage from Gsn-/- mice failed to elongate at the onset of puberty and remained rudimentary until approximately 9 weeks of age, early block (Gsn-/-(EB)). Second, after the mammary epithelium had filled the mammary fat pad, a complete lack of terminal branching, or late block, was observed (Gsn-/-(LB)). The Gsn-/-(EB) was seen in 70% of Gsn-/- mice and appeared to be dependent on a modifier gene(s) in addition to the loss of gelsolin. Gsn-/-(LB) was observed in all Gsn-/- mice. Terminal end buds (TEBs) were not evident in the mammary anlage from Gsn-/-(EB) mice until approximately 9 weeks of age. Cellular proliferation in the terminal ductal regions of Gsn-/-(EB) females was detected by bromodeoxyuridine incorporation, but was less than that found in the TEBs of age-matched controls. In mice deficient for gelsolin, mammary gland architecture was unaltered at the histological level. Lobuloalveolar development was delayed in response to pregnancy in mammary glands of Gsn-/- mice but was otherwise normal. Lactation and involution in the gelsolin-null animals were similar to those of wild-type mice. Transplantation of epithelium devoid of gelsolin into a wild-type (GsnWT) mammary fat pad resulted in proper arborization of the ductal tree. Transplantation of GsnWT epithelium into the Gsn-/- fat pad recapitulated the lack of terminal branching seen in Gsn-/- females. These results indicate that gelsolin is required in the mammary stroma for proper ductal morphogenesis. Our results provide the first evidence of an actin regulatory protein affecting mammary ductal growth through stromal-epithelial communication.
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Affiliation(s)
- M R Crowley
- Division of Experimental Pathology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, New York 14263, USA
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29
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Abstract
Gelsolin is an actin filament severing protein composed of six similar structured domains that differ with respect to actin, calcium and polyphospho-inositide binding. Previous work has established that gelsolin binds tropomyosin [Koepf, E.K. and Burtnick, L.D. (1992) FEBS Lett. 309, 56-58]. We have produced various specific gelsolin domains in Escherichia coli in order to establish which of the six domains binds tropomyosin. Gelsolin domains 1-3 (G1-3), G1-2 and G2 all bind tropomyosin in a pH and calcium insensitive manner whereas binding of G4-6 to tropomyosin was barely detectable under the conditions tested. We conclude that gelsolin binds tropomyosin via domain 2 (G2).
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Affiliation(s)
- S K Maciver
- Genes and Development Group, Department of Biomedical Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, UK.
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30
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Funatsu N, Kumanogoh H, Sokawa Y, Maekawa S. Identification of gelsolin as an actin regulatory component in a triton insoluble low density fraction (raft) of newborn bovine brain. Neurosci Res 2000; 36:311-7. [PMID: 10771109 DOI: 10.1016/s0168-0102(99)00125-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A membrane microdomain enriched in cholesterol and glycosphingolipids, or so called 'raft' region, was found to contain many signal transducing proteins such as GPI-anchored cell adhesion molecules, trimeric G proteins, and protein tyrosine kinases. In previous studies, we showed that the raft region obtained from rat brain contains two cytoskeletal proteins, tubulin and actin, as the major components in addition to these signal transducing proteins. In this study, to know the biochemical mechanisms regulating the cytoskeletal organization in this region, actin regulatory activities in raft were surveyed. We found the presence of a Ca(2+)-dependent actin nucleation promoting activity in raft. The solubilization and column fractionation of this activity combined with western blotting and immunoprecipitation showed that gelsolin is one of the actin regulatory proteins in raft.
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Affiliation(s)
- N Funatsu
- Department of Biotechnology, Faculty of Textile Science, Kyoto Institute of Technology, Kyoto, Japan
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31
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Kwak JY, Uhlinger DJ. Downregulation of phospholipase D by protein kinase A in a cell-free system of human neutrophils. Biochem Biophys Res Commun 2000; 267:305-10. [PMID: 10623615 DOI: 10.1006/bbrc.1999.1941] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Agents which elevate cellular cAMP are known to inhibit the activation of phospholipase D (PLD) in human neutrophils. The PLD activity of human neutrophils requires protein factors in both membrane and cytosolic fractions. We have studied the regulation of PLD by the catalytic subunit of protein kinase A (cPKA) in a cell-free system. cPKA significantly inhibited GTPgammaS-stimulated PLD activity but had no effect on phorbol ester-activated PLD activity. Pretreatment of plasma membranes with cPKA and ATP inhibited subsequent PLD activation upon reconstitution with untreated cytosol. RhoA, which is known to be a plasma membrane activator of PLD, was dissociated from PKA-treated plasma membrane by addition of cytosol. Plasma membrane-associated RhoA in human neutrophils was phosphorylated by cPKA. The PKA-phosphorylated form of RhoA was more easily extracted from membranes by RhoGDI than the unphosphorylated form. These results suggest that inhibition of neutrophil PLD by PKA may be due to phosphorylation of RhoA on the plasma membrane.
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Affiliation(s)
- J Y Kwak
- Department of Biochemistry, Dong-A University College of Medicine, Pusan, 602-103, Korea.
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32
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Defacque H, Egeberg M, Antzberger A, Ansorge W, Way M, Griffiths G. Actin assembly induced by polylysine beads or purified phagosomes: Quantitation by a new flow cytometry assay. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/1097-0320(20000901)41:1<46::aid-cyto7>3.0.co;2-f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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33
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Honda A, Nogami M, Yokozeki T, Yamazaki M, Nakamura H, Watanabe H, Kawamoto K, Nakayama K, Morris AJ, Frohman MA, Kanaho Y. Phosphatidylinositol 4-phosphate 5-kinase alpha is a downstream effector of the small G protein ARF6 in membrane ruffle formation. Cell 1999; 99:521-32. [PMID: 10589680 DOI: 10.1016/s0092-8674(00)81540-8] [Citation(s) in RCA: 650] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synthesis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], a signaling phospholipid, is primarily carried out by phosphatidylinositol 4-phosphate 5-kinase [PI(4)P5K], which has been reported to be regulated by RhoA and Rac1. Unexpectedly, we find that the GTPgammaS-dependent activator of PI(4)P5Kalpha is the small G protein ADP-ribosylation factor (ARF) and that the activation strictly requires phosphatidic acid, the product of phospholipase D (PLD). In vivo, ARF6, but not ARF1 or ARF5, spatially coincides with PI(4)P5Kalpha. This colocalization occurs in ruffling membranes formed upon AIF4 and EGF stimulation and is blocked by dominant-negative ARF6. PLD2 similarly translocates to the ruffles, as does the PH domain of phospholipase Cdelta1, indicating locally elevated PI(4,5)P2. Thus, PI(4)P5Kalpha is a downstream effector of ARF6 and when ARF6 is activated by agonist stimulation, it triggers recruitment of a diverse but interactive set of signaling molecules into sites of active cytoskeletal and membrane rearrangement.
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Affiliation(s)
- A Honda
- Department of Biological Information, Tokyo Institute of Technology, Yokohama, Japan
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34
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Banno Y, Fujita H, Ono Y, Nakashima S, Ito Y, Kuzumaki N, Nozawa Y. Differential phospholipase D activation by bradykinin and sphingosine 1-phosphate in NIH 3T3 fibroblasts overexpressing gelsolin. J Biol Chem 1999; 274:27385-91. [PMID: 10488069 DOI: 10.1074/jbc.274.39.27385] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gelsolin, an actin-binding protein, shows a strong ability to bind to phosphatidylinositol 4,5-bisphosphate (PIP(2)). Here we showed in in vitro experiments that gelsolin inhibited recombinant phospholipase D1 (PLD1) and PLD2 activities but not the oleate-dependent PLD and that this inhibition was not reversed by increasing PIP(2) concentration. To investigate the role of gelsolin in agonist-mediated PLD activation, we used NIH 3T3 fibroblasts stably transfected with the cDNA for human cytosolic gelsolin. Gelsolin overexpression suppressed bradykinin-induced activation of phospholipase C (PLC) and PLD. On the other hand, sphingosine 1-phosphate (S1P)-induced PLD activation could not be modified by gelsolin overexpression, whereas PLC activation was suppressed. PLD activation by phorbol myristate acetate or Ca(2+) ionophore A23187 was not affected by gelsolin overexpression. Stimulation of control cells with either bradykinin or S1P caused translocation of protein kinase C (PKC) to the membranes. Translocation of PKC-alpha and PKC-beta1 but not PKC-epsilon was reduced in gelsolin-overexpressed cells, whereas phosphorylation of mitogen-activated protein kinase was not changed. S1P-induced PLC activation and mitogen-activated protein kinase phosphorylation were sensitive to pertussis toxin, but PLD response was insensitive to such treatment, suggesting that S1P induced PLD activation via certain G protein distinct from G(i) for PLC and mitogen-activated protein kinase pathway. Our results suggest that gelsolin modulates bradykinin-mediated PLD activation via suppression of PLC and PKC activities but did not affect S1P-mediated PLD activation.
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Affiliation(s)
- Y Banno
- Department of Biochemistry, Gifu University School of Medicine, Tsukasamachi-40, Gifu 500-8705, Japan
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35
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Strand AM, Lauritzen L, Vinggaard AM, Hansen HS. The subcellular localization of phospholipase D activities in rat Leydig cells. Mol Cell Endocrinol 1999; 152:99-110. [PMID: 10432228 DOI: 10.1016/s0303-7207(99)00057-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Rat Leydig cells contain a phospholipase D (PLD), which can be activated by vasopressin and phorbol ester. In order to clarify which Leydig cell organelles that express PLD activity, the subcellular localization of two differently regulated PLD activities was investigated by subcellular fractionation on a 40% (v/v) self-generating Percoll gradient. PLD activities in broken cells were estimated using radiolabeled didecanoylphosphatidylcholine as a substrate. Initial experiments revealed the presence of an oleate Mg2+ -activated PLD and a phosphatidylinositol 4,5-bisphosphate-activated PLD (PIP2-PLD) in the microsomal fraction of Leydig cells. The latter activity could be further stimulated by recombinant nonmyristoylated ADP ribosylating factor 1 (ARF1) plus GTPgammaS. The peak of oleate Mg2+ -PLD activity colocalized with the plasma membrane marker, whereas the highest specific activity of the PIP2-PLD activity was found in fractions with a slightly lower density than those containing the plasma membrane and trans-Golgi marker enzymes. In order to localize phorbol ester-stimulated PLD activity in intact Leydig cells, the cells were prelabeled with [14C]-palmitate and then stimulated for 15 min with 100 nM 4-beta-phorbol-12-myristate-13-acetate (PMA) in the presence of ethanol or butanol. The PLD product [14C]-phosphatidylethanol, expressed as the percentage of total labeled phospholipids in the fraction, was slightly increased in all Percoll fractions and showed a prominent peak in the fractions containing plasma membrane, trans-Golgi, and fractions of slightly lower density. The PMA-induced formation of [14C]-phosphatidylbutanol could be inhibited dose-dependently with brefeldin A suggesting that the activation of PLD by the phorbol ester was mediated by ARF.
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Affiliation(s)
- A M Strand
- Department of Pharmacology, The Royal Danish School of Pharmacy, Copenhagen
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36
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Mielnicki LM, Ying AM, Head KL, Asch HL, Asch BB. Epigenetic regulation of gelsolin expression in human breast cancer cells. Exp Cell Res 1999; 249:161-76. [PMID: 10328963 DOI: 10.1006/excr.1999.4461] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Gelsolin is a multifunctional, actin-binding protein that is greatly decreased in many transformed cell lines and tumor tissues, including breast cancers. Downregulation of gelsolin RNA occurs in most breast cancers of rats, mice, and humans, but gross mutations of the gelsolin gene have not been found. Here we demonstrate by PCR and RT-PCR analysis that there are no point mutations in putative regulatory regions or the entire coding region of the cytoplasmic isoform of the gelsolin gene in human breast cancer cells (BCC). To determine if epigenetic modification is involved in downregulating gelsolin expression in MDA-MB-231 (MDA231), MCF7, and T47D BCC, we have used Southern blot analysis, 5-azacytidine (5aza) treatment, and trichostatin A (TSA) treatment. Southern blot analysis performed on genomic DNA demonstrated altered CpG methylation within intron 1 in DNA from all BCC compared to normal, mortal human mammary epithelial cells (HMEC). Treatment of the BCC with 5aza converted the DNA restriction pattern to that seen in untreated HMEC genomic DNA and caused modest increases in gelsolin RNA and protein. Incubation with TSA, an inhibitor of histone deacetylase, induced a dramatic upregulation of gelsolin RNA and protein levels which preceded apoptotic death of all BCC within 48-60 h. Our data support a role for epigenetic changes in chromatin structure leading to downregulation of gelsolin expression in human breast cancer. To our knowledge, this is the first example of a tumor suppressor gene downregulated in human breast cancer by changes in histone acetylation.
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Affiliation(s)
- L M Mielnicki
- Department of Experimental Pathology, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, New York 14263, USA
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37
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El Hadj NB, Popoff MR, Marvaud JC, Payrastre B, Boquet P, Geny B. G-protein-stimulated phospholipase D activity is inhibited by lethal toxin from Clostridium sordellii in HL-60 cells. J Biol Chem 1999; 274:14021-31. [PMID: 10318815 DOI: 10.1074/jbc.274.20.14021] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lethal toxin (LT) from Clostridium sordellii has been shown in HeLa cells to glucosylate and inactivate Ras and Rac and, hence, to disorganize the actin cytoskeleton. In the present work, we demonstrate that LT treatment provokes the same effects in HL-60 cells. We show that guanosine 5'-O-(3-thiotriphosphate)-stimulated phospholipase D (PLD) activity is inhibited in a time- and dose-dependent manner after an overnight treatment with LT. A similar dose response to the toxin was found when PLD activity was stimulated by phorbol 12-myristate 13-acetate via the protein kinase C pathway. The toxin effect on actin organization seemed unlikely to account directly for PLD inhibition as cytochalasin D and iota toxin from Clostridium perfringens E disorganize the actin cytoskeleton without modifying PLD activity. However, the enzyme inhibition and actin cytoskeleton disorganization could both be related to a major decrease observed in phosphatidylinositol 4,5-bisphosphate (PtdIns(4, 5)P2). Likely in a relationship with this decrease, recombinant ADP-ribosylation factor, RhoA, Rac, and RalA were not able to reconstitute PLD activity in LT-treated cells permeabilized and depleted of cytosol. Studies of phosphoinositide kinase activities did not allow us to attribute the decrease in PtdIns(4,5)P2 to inactivation of PtdIns4P 5-kinase. LT was also found to provoke a major inhibition in phosphatidylinositol 3-kinase that could not account for the inhibition of PLD activity because wortmannin, at doses that fully inhibit phosphatidylinositol 3-kinase, had no effect on the phospholipase activity. Among the three small G-proteins, Ras, Rac, and RalA, inactivated by LT and involved in PLD regulation, inactivation of Ral proteins appeared to be responsible for PLD inhibition as LT toxin (strain 9048) unable to glucosylate Ral proteins did not modify PLD activity. In HL-60 cells, LT treatment appeared also to modify cytosol components in relationship with PLD inhibition as a cytosol prepared from LT-treated cells was less efficient than one from control HL-60 cells in stimulating PLD activity. Phosphatidylinositol transfer proteins involved in the regulation of polyphosphoinositides and ADP-ribosylation factor, a major cytosolic PLD activator in HL-60 cells, were unchanged, whereas the level of cytosolic protein kinase Calpha was decreased after LT treatment. We conclude that in HL-60 cells, lethal toxin from C. sordellii, in inactivating small G-proteins involved in PLD regulation, provokes major modifications at the membrane and the cytosol levels that participate in the inhibition of PLD activity. Although Ral appeared to play an essential role in PLD activity, we discuss the role of other small G-proteins inactivated by LT in the different modifications observed in HL-60 cells.
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Affiliation(s)
- N B El Hadj
- INSERM U332, ICGM, 22 rue Méchain, 75014 Paris, France
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38
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Asch HL, Winston JS, Edge SB, Stomper PC, Asch BB. Down-regulation of gelsolin expression in human breast ductal carcinoma in situ with and without invasion. Breast Cancer Res Treat 1999; 55:179-88. [PMID: 10481945 DOI: 10.1023/a:1006203632228] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Expression of gelsolin, an actin filament regulatory protein, in human breast ductal carcinoma in situ (DCIS) was analyzed by immunohistochemistry using a monoclonal antibody. Formalin-fixed paraffin-embedded tissues from 59 pure DCIS specimens and 33 DCIS specimens with associated invasive components were evaluated for gelsolin reactivity and compared to eight normal breast cases and 76 invasive breast cancers. The proportion of cases exhibiting negative/low expression of gelsolin in the epithelium was as follows -- normal, 0%; pure DCIS, 56%; DCIS associated with invasion, 58% in the DCIS component and 66% in the invasive component; invasive carcinoma, 70%. These data demonstrate that down-regulation of gelsolin expression in breast epithelium frequently parallels progression to malignancy. Testing gelsolin expression (normal vs. negative/low levels) in the DCIS lesions for associations with patient age or any of the following histopathologic parameters revealed no significant (95% probability level) correlations -- tumor size; pathologic (Van Nuys system) grade; nuclear grade; necrosis; presence of histologic calcifications; presence or type of adjacent benign lesions; architectural histologic pattern; and mammographic extent. Gelsolin loss was more commonly associated with mammographic soft tissue lesions as compared to calcified lesions (P = 0.009). A positive trend of borderline significance (P = 0.06) found in the DCIS with invasion group was a correlation between down-regulated gelsolin expression in the DCIS component and size (< versus > or = 15 mm) of the invasive tumor. In conclusion, reduced gelsolin protein is detectable in at least half of breast lesions which have progressed to DCIS. The trend between increasing gelsolin loss and malignant progression from normal epithelium to DCIS to invasive breast cancer (P < 0.0001) suggests additional investigation is needed to determine the potential of altered gelsolin expression as a marker for prognosis and for therapeutic interventions in breast cancer.
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MESH Headings
- Adult
- Aged
- Biomarkers, Tumor/biosynthesis
- Biomarkers, Tumor/genetics
- Breast Diseases/genetics
- Breast Diseases/metabolism
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma in Situ/classification
- Carcinoma in Situ/genetics
- Carcinoma in Situ/metabolism
- Carcinoma in Situ/pathology
- Carcinoma, Ductal, Breast/classification
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Ductal, Breast/pathology
- Disease Progression
- Female
- Gelsolin/biosynthesis
- Gelsolin/genetics
- Gene Expression Regulation, Neoplastic
- Humans
- Middle Aged
- Neoplasm Invasiveness/genetics
- Neoplasm Proteins/biosynthesis
- Neoplasm Proteins/genetics
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Affiliation(s)
- H L Asch
- Department of Pathology, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
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Abstract
Several new members of the gelsolin family have been discovered in the past year. Determination of the structure of gelsolin and identification of lysophosphatidic acid as a negative regulator provide novel functional insights. Gelsolin is an obligate downstream effector of Rac for motility in dermal fibroblasts, regulates phosphoinositide signaling pathways and ion channel function in vivo, and acts as both a regulator and effector of apoptosis.
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Affiliation(s)
- D J Kwiatkowski
- Genetics Laboratory Hematology Division Brigham and Women's Hospital 221 Longwood Avenue Boston MA 02115 USA.
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40
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De Corte V, Demol H, Goethals M, Van Damme J, Gettemans J, Vandekerckhove J. Identification of Tyr438 as the major in vitro c-Src phosphorylation site in human gelsolin: a mass spectrometric approach. Protein Sci 1999; 8:234-41. [PMID: 10210201 PMCID: PMC2144107 DOI: 10.1110/ps.8.1.234] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Gelsolin is an actin-binding protein (82 kDa) consisting of six repeated segments (S1-S6), each approximately 120 residues long. It interacts with phospholipids and we previously showed that phosphatidylinositol 4,5-bisphosphate promotes phosphorylation of gelsolin by the tyrosine kinase c-Src. We used a combination of different methods, such as thin-layer chromatography and anti-phosphotyrosine-agarose immunoprecipitation of phosphopeptides combined with matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) and post source decay (PSD) analysis, to identify the phosphorylation sites in gelsolin. The major phosphorylation site (Tyr438) was located in subdomain 4 (S4). Phosphorylation of gelsolin in the gelsolin-actin2 complex was inhibited by 90%. Gelsolin phosphorylation by c-Src in the presence of lysophosphatidic acid also revealed Tyr438 as the most prominent site. Additional minor sites were found using the anti-phosphotyrosine bead immunoprecipitation method followed by MALDI-MS and PSD analysis. These sites, representing approximately 5% of the total phosphate incorporation, were identified as Tyr59, Tyr382, Tyr576, and Tyr624. Based on these results we generated antibodies which specifically recognize Tyr438 phosphorylated gelsolin.
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Affiliation(s)
- V De Corte
- Flanders Interuniversity Institute for Biotechnology, Department of Biochemistry, Faculty of Medicine, Universiteit Gent, Ghent, Belgium
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41
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Kinosian HJ, Newman J, Lincoln B, Selden LA, Gershman LC, Estes JE. Ca2+ regulation of gelsolin activity: binding and severing of F-actin. Biophys J 1998; 75:3101-9. [PMID: 9826630 PMCID: PMC1299981 DOI: 10.1016/s0006-3495(98)77751-3] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Regulation of the F-actin severing activity of gelsolin by Ca2+ has been investigated under physiologic ionic conditions. Tryptophan fluorescence intensity measurements indicate that gelsolin contains at least two Ca2+ binding sites with affinities of 2.5 x 10(7) M-1 and 1.5 x 10(5) M-1. At F-actin and gelsolin concentrations in the range of those found intracellularly, gelsolin is able to bind F-actin with half-maximum binding at 0.14 microM free Ca2+ concentration. Steady-state measurements of gelsolin-induced actin depolymerization suggest that half-maximum depolymerization occurs at approximately 0.4 microM free Ca2+ concentration. Dynamic light scattering measurements of the translational diffusion coefficient for actin filaments and nucleated polymerization assays for number concentration of actin filaments both indicate that severing of F-actin occurs slowly at micromolar free Ca2+ concentrations. The data suggest that binding of Ca2+ to the gelsolin-F-actin complex is the rate-limiting step for F-actin severing by gelsolin; this Ca2+ binding event is a committed step that results in a Ca2+ ion bound at a high-affinity, EGTA-resistant site. The very high affinity of gelsolin for the barbed end of an actin filament drives the binding reaction equilibrium toward completion under conditions where the reaction rate is slow.
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Affiliation(s)
- H J Kinosian
- Department of Physiology and Cell Biology, Albany Medical College, Albany, New York 12208, USA
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42
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Pettit EJ, Fay FS. Cytosolic free calcium and the cytoskeleton in the control of leukocyte chemotaxis. Physiol Rev 1998; 78:949-67. [PMID: 9790567 DOI: 10.1152/physrev.1998.78.4.949] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In response to a chemotactic gradient, leukocytes extravasate and chemotax toward the site of pathogen invasion. Although fundamental in the control of many leukocyte functions, the role of cytosolic free Ca2+ in chemotaxis is unclear and has been the subject of debate. Before becoming motile, the cell assumes a polarized morphology, as a result of modulation of the cytoskeleton by G protein and kinase activation. This morphology may be reinforced during chemotaxis by the intracellular redistribution of Ca2+ stores, cytoskeletal constituents, and chemoattractant receptors. Restricted subcellular distributions of signaling molecules, such as Ca2+, Ca2+/calmodulin, diacylglycerol, and protein kinase C, may also play a role in some types of leukocyte. Chemotaxis is an essential function of most cells at some stage during their development, and a deeper understanding of the molecular signaling and structural components involved will enable rational design of therapeutic strategies in a wide variety of diseases.
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Affiliation(s)
- E J Pettit
- Biomedical Imaging Group, University of Massachusetts Medical Center, Worcester, USA
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43
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Steed PM, Clark KL, Boyar WC, Lasala DJ. Characterization of human PLD2 and the analysis of PLD isoform splice variants. FASEB J 1998; 12:1309-17. [PMID: 9761774 DOI: 10.1096/fasebj.12.13.1309] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Phospholipase D (PLD) cleaves phosphatidylcholine in response to a variety of cell stimuli to release phosphatidic acid, which is associated with a number of cellular responses including regulated secretion, mitogenesis, and cytoskeletal changes. Recent advances in this field include the reports of cDNA sequences for two mammalian PLD isoforms: human PLD1 and rodent PLD2. We report the characterization of cDNA encoding human PLD2. In these experiments, we uncovered alternate splice variants of both human isoforms and evaluated the relative abundance of these messages by reverse transcriptase polymerase chain reaction, thereby indicating the physiologically relevant forms. Further, Northern hybridization experiments defined the tissue distribution of the human PLD messages. Human PLD1 does not appear to be an abundant message in any tissue tested whereas levels of human PLD2 mRNA apparently were higher and more variable. The specific activity and regulation of recombinant human PLD2 are indistinguishable from that of recombinant mouse PLD2. Analysis of the amino acid sequences of both human isoforms revealed important putative Pleckstrin homology domains and identified additional members of the PLD gene family that help to delimit the catalytic domain. The presence of Pleckstrin homology domains in the PLDs resolves several contradictory observations regarding PLD regulation and the domain structure of the proteins.
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Affiliation(s)
- P M Steed
- Novartis Institute for Biomedical Research, Summit, New Jersey 07901, USA.
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44
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Abstract
The three-dimensional intracellular network formed by the filamentous polymers comprising the cytoskeletal affects the way cells sense their extracellular environment and respond to stimuli. Because the cytoskeleton is viscoelastic, it provides a continuous mechanical coupling throughout the cell that changes as the cytoskeleton remodels. Such mechanical effects, based on network formation, can influence ion channel activity at the plasma membrane of cells and may conduct mechanical stresses from the cell membrane to internal organelles. As a result, both rapid responses such as changes in intracellular Ca2+ and slower responses such as gene transcription or the onset of apoptosis can be elicited or modulated by mechanical perturbations. In addition to mechanical features, the cytoskeleton also provides a large negatively charged surface on which many signaling molecules including protein and lipid kinases, phospholipases, and GTPases localize in response to activation of specific transmembrane receptors. The resulting spatial localization and concomitant change in enzymatic activity can alter the magnitude and limit the range of intracellular signaling events.
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Affiliation(s)
- P A Janmey
- Experimental Medicine Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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45
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Hsuan JJ, Minogue S, dos Santos M. Phosphoinositide 4- and 5-kinases and the cellular roles of phosphatidylinositol 4,5-bisphosphate. Adv Cancer Res 1998; 74:167-216. [PMID: 9561269 DOI: 10.1016/s0065-230x(08)60767-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- J J Hsuan
- Ludwig Institute for Cancer Research, University College London Medical School, London, United Kingdom
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46
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Aunis D. Exocytosis in chromaffin cells of the adrenal medulla. INTERNATIONAL REVIEW OF CYTOLOGY 1998; 181:213-320. [PMID: 9522458 DOI: 10.1016/s0074-7696(08)60419-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The chromaffin cell has been used as a model to characterize releasable components present in secretory granules and to understand the cellular mechanisms involved in catecholamine release. Recent physiological and biochemical developments have revealed that molecular mechanisms implicated in granule trafficking are conserved in all eukaryotic species: a rise in intracellular calcium triggers regulated exocytosis, and highly conserved proteins are essential elements which interact with each other to form a molecular scaffolding, ensuring the docking of granules at the plasma membrane, and perhaps membrane fusion. However, the mechanisms regulating secretion are multiple and cell specific. They operate at different steps along the life of a granule, from the time of granule biosynthesis up to the last step of exocytosis. With regard to cell specificity, noradrenaline and adrenaline chromaffin cells display different receptor and signaling characteristics that may be important to exocytosis. Characterization of regulated exocytosis in chromaffin cells provides not only fundamental knowledge of neurosecretion but is of additional importance as these cells are used for therapeutic purposes.
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Affiliation(s)
- D Aunis
- Biologie de la Communication Cellulaire, Unité INSERM U-338, Strasbourg, France
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47
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Janmey PA, Stossel TP, Allen PG. Deconstructing gelsolin: identifying sites that mimic or alter binding to actin and phosphoinositides. CHEMISTRY & BIOLOGY 1998; 5:R81-5. [PMID: 9571211 DOI: 10.1016/s1074-5521(98)90631-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Gelsolin is involved in cytoskeletal remodeling as it can fragment and guide reassembly of actin networks. Recent advances in defining the structure of gelsolin identified functionally important sites. These structural insights could lead to the design of small molecule analogs to enhance, inhibit or mimic the functions of gelsolin.
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Affiliation(s)
- P A Janmey
- Experimental Medicine Division, Brigham and Women's Hospital, Boston, MA 02115, USA.
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48
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Caumont AS, Galas MC, Vitale N, Aunis D, Bader MF. Regulated exocytosis in chromaffin cells. Translocation of ARF6 stimulates a plasma membrane-associated phospholipase D. J Biol Chem 1998; 273:1373-9. [PMID: 9430671 DOI: 10.1074/jbc.273.3.1373] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The ADP-ribosylation factor (ARF) GTP-binding proteins have been implicated in a wide range of vesicle transport and fusion steps along the secretory pathway. In chromaffin cells, ARF6 is specifically associated with the membrane of secretory chromaffin granules. Since ARF6 is an established regulator of phospholipase D (PLD), we have examined the intracellular distribution of ARF6 and PLD activity in resting and stimulated chromaffin cells. We found that stimulation of intact chromaffin cells or direct elevation of cytosolic calcium in permeabilized cells triggered the rapid translocation of ARF6 from secretory granules to the plasma membrane and the concomitant activation of PLD in the plasma membrane. To probe the existence of an ARF6-dependent PLD in chromaffin cells, we measured the PLD activity in purified plasma membranes. PLD could be activated by a nonhydrolyzable analogue of GTP and by recombinant myristoylated ARF6 and inhibited by specific anti-ARF6 antibodies. Furthermore, a synthetic myristoylated peptide corresponding to the N-terminal domain of ARF6 inhibited both PLD activity and catecholamine secretion in calcium-stimulated chromaffin cells. The possibility that ARF6 participates in the exocytotic reaction by controlling a plasma membrane-bound PLD and thereby generating fusogenic lipids at the exocytotic sites is discussed.
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Affiliation(s)
- A S Caumont
- INSERM, U-338 Biologie de la Communication Cellulaire, Strasbourg, France
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49
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Decreased Expression of the Actin-Binding Protein Gelsolin in Endometrial and Ovarian Adenocarcinomas. ACTA ACUST UNITED AC 1998. [DOI: 10.1097/00022744-199803000-00006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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50
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Sun HQ, Lin KM, Yin HL. Gelsolin modulates phospholipase C activity in vivo through phospholipid binding. J Biophys Biochem Cytol 1997; 138:811-20. [PMID: 9265648 PMCID: PMC2138049 DOI: 10.1083/jcb.138.4.811] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Gelsolin and CapG are actin regulatory proteins that remodel the cytoskeleton in response to phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+ during agonist stimulation. A physiologically relevant rise in Ca2+ increases their affinity for PIP2 and can promote significant interactions with PIP2 in activated cells. This may impact divergent PIP2- dependent signaling processes at the level of substrate availability. We found that CapG overexpression enhances PDGF-stimulated phospholipase Cgamma (PLCgamma) activity (Sun, H.-q., K. Kwiatkowska, D.C. Wooten, and H.L. Yin. 1995. J. Cell Biol. 129:147-156). In this paper, we examined the ability of gelsolin and CapG to compete with another PLC for PIP2 in live cells, in semiintact cells, and in vitro. We found that CapG and gelsolin overexpression profoundly inhibited bradykinin-stimulated PLCbeta. Inhibition occurred at or after the G protein activation step because overexpression also reduced the response to direct G protein activation with NaF. Bradykinin responsiveness was restored after cytosolic proteins, including gelsolin, leaked out of the overexpressing cells. Conversely, exogenous gelsolin added to permeabilized cells inhibited response in a dose-dependent manner. The washout and addback experiments clearly establish that excess gelsolin is the primary cause of PLC inhibition in cells. In vitro experiments showed that gelsolin and CapG stimulated as well as inhibited PLCbeta, and only gelsolin domains containing PIP2-binding sites were effective. Inhibition was mitigated by increasing PIP2 concentration in a manner consistent with competition between gelsolin and PLCbeta for PIP2. Gelsolin and CapG also had biphasic effects on tyrosine kinase- phosphorylated PLCgamma, although they inhibited PLCgamma less than PLCbeta. Our findings indicate that as PIP2 level and availability change during signaling, cross talk between PIP2-regulated proteins provides a selective mechanism for positive as well as negative regulation of the signal transduction cascade.
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Affiliation(s)
- H q Sun
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas 75235-9040, USA
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