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Polarized Organization of the Cytoskeleton: Regulation by Cell Polarity Proteins. J Mol Biol 2018; 430:3565-3584. [DOI: 10.1016/j.jmb.2018.06.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 06/09/2018] [Accepted: 06/13/2018] [Indexed: 01/02/2023]
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PPIP5K1 interacts with the exocyst complex through a C-terminal intrinsically disordered domain and regulates cell motility. Cell Signal 2016; 28:401-411. [PMID: 26854614 DOI: 10.1016/j.cellsig.2016.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/01/2016] [Accepted: 02/02/2016] [Indexed: 11/24/2022]
Abstract
Cellular signaling involves coordinated regulation of many events. Scaffolding proteins are crucial regulators of cellular signaling, because they are able to affect numerous events by coordinating specific interactions among multiple protein partners in the same pathway. Scaffolding proteins often contain intrinsically disordered regions (IDR) that facilitate the formation and function of distinct protein complexes. We show that PPIP5K1 contains an unusually long and evolutionarily conserved IDR. To investigate the biological role(s) of this domain, we identified interacting proteins using affinity purification coupled with mass spectrometry. Here, we report that PPIP5K1 is associated with a network of proteins that regulate vesicle-mediated transport. We further identified exocyst complex component 1 as a direct interactor with the IDR of PPIP5K1. Additionally, we report that knockdown of PPIP5K1 decreases motility of HeLa cells in a wound-healing assay. These results suggest that PPIP5K1 might play an important role in regulating function of exocyst complex in establishing cellular polarity and directional migration of cells.
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Méndez F, de Garay T, Rodríguez D, Rodríguez JF. Infectious bursal disease virus VP5 polypeptide: a phosphoinositide-binding protein required for efficient cell-to-cell virus dissemination. PLoS One 2015; 10:e0123470. [PMID: 25886023 PMCID: PMC4401730 DOI: 10.1371/journal.pone.0123470] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 02/18/2015] [Indexed: 11/19/2022] Open
Abstract
Infectious bursal disease virus (IBDV), a member of the Birnaviridae family, is a major avian pathogen responsible for an immunosuppressive disease affecting juvenile chickens. The IBDV genome is formed by two dsRNA segments. The largest one harbors two partially overlapping open reading frames encoding a non-structural polypeptide, known as VP5, and a large polyprotein, respectively. VP5 is non-essential for virus replication. However, it plays a major role in IBDV pathogenesis. VP5 accumulates at the plasma membrane (PM) of IBDV-infected cells. We have analyzed the mechanism underlying the VP5 PM targeting. Updated topological prediction algorithm servers fail to identify a transmembrane domain within the VP5 sequence. However, the VP5 polycationic C-terminal region, harboring three closely spaced patches formed by two or three consecutive basic amino acid residues (lysine or arginine), might account for its PM tropism. We have found that mutations, either C-terminal VP5 deletions or replacement of basic amino acids by alanine residues, that reduce the electropositive charge of the VP5 C-terminus abolish PM targeting. Lipid overlay assays performed with an affinity-purified Flag-tagged VP5 (FVP5) protein version show that this polypeptide binds several phosphoinositides (PIP), exhibiting a clear preference for monophosphate species. Experiments performed with FVP5 mutant proteins lacking the polycationic domain demonstrate that this region is essential for PIP binding. Data gathered with IBDV mutants expressing C-terminal deleted VP5 polypeptides generated by reverse genetics demonstrate that the VP5-PIP binding domain is required both for its PM targeting in infected cells, and for efficient virus dissemination. Data presented here lead us to hypothesize that IBDV might use a non-lytic VP5-dependent cell-to-cell spreading mechanism.
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Affiliation(s)
- Fernando Méndez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología-CSIC, Cantoblanco, 28049, Madrid, Spain
| | - Tomás de Garay
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología-CSIC, Cantoblanco, 28049, Madrid, Spain
| | - Dolores Rodríguez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología-CSIC, Cantoblanco, 28049, Madrid, Spain
| | - José F. Rodríguez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología-CSIC, Cantoblanco, 28049, Madrid, Spain
- * E-mail:
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Chakrabarti P, Kolay S, Yadav S, Kumari K, Nair A, Trivedi D, Raghu P. A dPIP5K dependent pool of phosphatidylinositol 4,5 bisphosphate (PIP2) is required for G-protein coupled signal transduction in Drosophila photoreceptors. PLoS Genet 2015; 11:e1004948. [PMID: 25633995 PMCID: PMC4310717 DOI: 10.1371/journal.pgen.1004948] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/09/2014] [Indexed: 12/02/2022] Open
Abstract
Multiple PIP2 dependent molecular processes including receptor activated phospholipase C activity occur at the neuronal plasma membranes, yet levels of this lipid at the plasma membrane are remarkably stable. Although the existence of unique pools of PIP2 supporting these events has been proposed, the mechanism by which they are generated is unclear. In Drosophila photoreceptors, the hydrolysis of PIP2 by G-protein coupled phospholipase C activity is essential for sensory transduction of photons. We identify dPIP5K as an enzyme essential for PIP2 re-synthesis in photoreceptors. Loss of dPIP5K causes profound defects in the electrical response to light and light-induced PIP2 dynamics at the photoreceptor membrane. Overexpression of dPIP5K was able to accelerate the rate of PIP2 synthesis following light induced PIP2 depletion. Other PIP2 dependent processes such as endocytosis and cytoskeletal function were unaffected in photoreceptors lacking dPIP5K function. These results provide evidence for the existence of a unique dPIP5K dependent pool of PIP2 required for normal Drosophila phototransduction. Our results define the existence of multiple pools of PIP2 in photoreceptors generated by distinct lipid kinases and supporting specific molecular processes at neuronal membranes. PIP2 has been implicated in multiple functions at the plasma membrane. Some of these require its hydrolysis by receptor-activated phospholipase C, whereas others, such as membrane transport and cytoskeletal function, involve the interaction of the intact lipid with cellular proteins. The mechanistic basis underlying the segregation of these two classes of PIP2 dependent functions is unknown; it has been postulated that this might involve unique pools of PIP2 generated by distinct phosphoinsoitide kinases. We have studied this question in Drosophila photoreceptors, a model system where sensory transduction requires robust phospholipase C mediated PIP2 hydrolysis. We find that the activity of phosphatidylinositol-4-phosphate 5 kinase encoded by dPIP5K is required to support normal sensory transduction and PIP2 dynamics in photoreceptors. Remarkably, non-PLC dependent functions of PIP2, such as vesicular transport and the actin cytoskeleton, were unaffected in dPIP5K mutants. Thus, dPIP5K supports a pool of PIP2 that is readily available to PLC, but has no role in sustaining other non-PLC mediated PIP2 dependent processes. These findings support the existence of at least two non-overlapping pools of PIP2 at the plasma membrane, and provide a platform for future studies of PIP2 regulation at the plasma membrane.
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Affiliation(s)
| | - Sourav Kolay
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
- Manipal University, Madhav Nagar, Manipal, Karnataka, India
| | - Shweta Yadav
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | - Kamalesh Kumari
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India
| | - Amit Nair
- Inositide Laboratory, Babraham Institute, Cambridge, United Kingdom
| | - Deepti Trivedi
- Inositide Laboratory, Babraham Institute, Cambridge, United Kingdom
| | - Padinjat Raghu
- Inositide Laboratory, Babraham Institute, Cambridge, United Kingdom
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
- * E-mail:
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Naguib A, Bencze G, Engle DD, Chio IIC, Herzka T, Watrud K, Bencze S, Tuveson DA, Pappin DJ, Trotman LC. p53 mutations change phosphatidylinositol acyl chain composition. Cell Rep 2014; 10:8-19. [PMID: 25543136 DOI: 10.1016/j.celrep.2014.12.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 10/27/2014] [Accepted: 12/04/2014] [Indexed: 01/01/2023] Open
Abstract
Phosphatidylinositol phosphate (PIP) second messengers relay extracellular growth cues through the phosphorylation status of the inositol sugar, a signal transduction system that is deregulated in cancer. In stark contrast to PIP inositol head-group phosphorylation, changes in phosphatidylinositol (PI) lipid acyl chains in cancer have remained ill-defined. Here, we apply a mass-spectrometry-based method capable of unbiased high-throughput identification and quantification of cellular PI acyl chain composition. Using this approach, we find that PI lipid chains represent a cell-specific fingerprint and are unperturbed by serum-mediated signaling in contrast to the inositol head group. We find that mutation of Trp53 results in PIs containing reduced-length fatty acid moieties. Our results suggest that the anchoring tails of lipid second messengers form an additional layer of PIP signaling in cancer that operates independently of PTEN/PI3-kinase activity but is instead linked to p53.
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Affiliation(s)
- Adam Naguib
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Gyula Bencze
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Dannielle D Engle
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Iok I C Chio
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Tali Herzka
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Kaitlin Watrud
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Szilvia Bencze
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - David A Tuveson
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Darryl J Pappin
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Lloyd C Trotman
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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Martin TFJ. PI(4,5)P₂-binding effector proteins for vesicle exocytosis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:785-93. [PMID: 25280637 DOI: 10.1016/j.bbalip.2014.09.017] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/20/2014] [Accepted: 09/23/2014] [Indexed: 12/27/2022]
Abstract
PI(4,5)P₂participates directly in priming and possibly in fusion steps of Ca²⁺-triggered vesicle exocytosis. High concentration nanodomains of PI(4,5)P₂reside on the plasma membrane of neuroendocrine cells. A subset of vesicles that co-localize with PI(4,5)P₂ domains appear to undergo preferential exocytosis in stimulated cells. PI(4,5)P₂directly regulates vesicle exocytosis by recruiting and activating PI(4,5)P₂-binding proteins that regulate SNARE protein function including CAPS, Munc13-1/2, synaptotagmin-1, and other C2 domain-containing proteins. These PI(4,5)P₂effector proteins are coincidence detectors that engage in multiple interactions at vesicle exocytic sites. The SNARE protein syntaxin-1 also binds to PI(4,5)P₂, which promotes clustering, but an activating role for PI(4,5)P₂in syntaxin-1 function remains to be fully characterized. Similar principles underlie polarized constitutive vesicle fusion mediated in part by the PI(4,5)P₂-binding subunits of the exocyst complex (Sec3, Exo70). Overall, focal vesicle exocytosis occurs at sites landmarked by PI(4,5)P2, which serves to recruit and/or activate multifunctional PI(4,5)P₂-binding proteins. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Thomas F J Martin
- Biochemistry Department, University of Wisconsin, 433 Babcock Drive, Madison, WI 53706, USA.
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Reversi A, Loeser E, Subramanian D, Schultz C, De Renzis S. Plasma membrane phosphoinositide balance regulates cell shape during Drosophila embryo morphogenesis. ACTA ACUST UNITED AC 2014; 205:395-408. [PMID: 24798734 PMCID: PMC4018783 DOI: 10.1083/jcb.201309079] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ratio of different phosphoinositide species coordinates actomyosin contractility and plasma membrane expansion during tissue morphogenesis, thus ensuring proper cell shape. Remodeling of cell shape during morphogenesis is driven by the coordinated expansion and contraction of specific plasma membrane domains. Loss of this coordination results in abnormal cell shape and embryonic lethality. Here, we show that plasma membrane lipid composition plays a key role in coordinating plasma membrane contraction during expansion. We found that an increase in PI(4,5)P2 levels caused premature actomyosin contraction, resulting in the formation of shortened cells. Conversely, acute depletion of PI(4,5)P2 blocked plasma membrane expansion and led to premature actomyosin disassembly. PI(4,5)P2-mediated contractility is counteracted by PI(3,4,5)P3 and the zygotic gene bottleneck, which acts by limiting myosin recruitment during plasma membrane expansion. Collectively, these data support a model in which the ratio of PI(4,5)P2/PI(3,4,5)P3 coordinates actomyosin contractility and plasma membrane expansion during tissue morphogenesis, thus ensuring proper cell shape.
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Affiliation(s)
- Alessandra Reversi
- European Molecular Biology Laboratory (EMBL) Heidelberg, 69117 Heidelberg, Germany
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Penniston JT, Padányi R, Pászty K, Varga K, Hegedus L, Enyedi A. Apart from its known function, the plasma membrane Ca²⁺ATPase can regulate Ca²⁺ signaling by controlling phosphatidylinositol 4,5-bisphosphate levels. J Cell Sci 2013; 127:72-84. [PMID: 24198396 DOI: 10.1242/jcs.132548] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasma membrane Ca(2+) ATPases (PMCAs, also known as ATP2B1-ATP2B4) are known targets of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P₂], but if and how they control the PtdIns(4,5)P₂ pool has not been considered. We demonstrate here that PMCAs protect PtdIns(4,5)P₂ in the plasma membrane from hydrolysis by phospholipase C (PLC). Comparison of active and inactive PMCAs indicates that the protection operates by two mechanisms; one requiring active PMCAs, the other not. It appears that the mechanism requiring activity is the removal of the Ca(2+) required for sustained PLC activity, whereas the mechanism not requiring activity is PtdIns(4,5)P₂ binding. We show that in PMCA overexpressing cells, PtdIns(4,5)P₂ binding can lead to less inositol 1,4,5-triphosphate (InsP₃) and diminished Ca(2+) release from intracellular Ca(2+) pools. Inspection of a homology model of PMCA suggests that PMCAs have a conserved cluster of basic residues forming a 'blue collar' at the interface between the membrane core and the cytoplasmic domains. By molecular dynamics simulation, we found that the blue collar forms four binding pockets for the phosphorylated inositol head group of PtdIns(4,5)P₂; these pockets bind PtdIns(4,5)P₂ strongly and frequently. Our studies suggest that by having the ability to bind PtdIns(4,5)P₂, PMCAs can control the accessibility of PtdIns(4,5)P₂ for PLC and other PtdIns(4,5)P₂-mediated processes.
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Affiliation(s)
- John T Penniston
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1025 Budapest, Hungary
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Discovery of the inhibitory effect of a phosphatidylinositol derivative on P-glycoprotein by virtual screening followed by in vitro cellular studies. PLoS One 2013; 8:e60679. [PMID: 23593281 PMCID: PMC3621910 DOI: 10.1371/journal.pone.0060679] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/01/2013] [Indexed: 11/23/2022] Open
Abstract
P-glycoprotein is capable of effluxing a broad range of cytosolic and membrane penetrating xenobiotic substrates, thus leading to multi-drug resistance and posing a threat for the therapeutic treatment of several diseases, including cancer and central nervous disorders. Herein, a virtual screening campaign followed by experimental validation in Caco-2, MDKCII, and MDKCII mdr1 transfected cell lines has been conducted for the identification of novel phospholipids with P-gp transportation inhibitory activity. Phosphatidylinositol-(1,2-dioctanoyl)-sodium salt (8∶0 PI) was found to significantly inhibit transmembrane P-gp transportation in vitro in a reproducible-, cell line-, and substrate-independent manner. Further tests are needed to determine whether this and other phosphatidylinositols could be co-administered with oral drugs to successfully increase their bioavailability. Moreover, as phosphatidylinositols and phosphoinositides are present in the human diet and are known to play an important role in signal transduction and cell motility, our finding could be of substantial interest for nutrition science as well.
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