1
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Buckley C, Lee MD, Zhang X, Wilson C, McCarron JG. Signalling switches maintain intercellular communication in the vascular endothelium. Br J Pharmacol 2024. [PMID: 38651236 DOI: 10.1111/bph.16366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND AND PURPOSE The single layer of cells lining all blood vessels, the endothelium, is a sophisticated signal co-ordination centre that controls a wide range of vascular functions including the regulation of blood pressure and blood flow. To co-ordinate activities, communication among cells is required for tissue level responses to emerge. While a significant form of communication occurs by the propagation of signals between cells, the mechanism of propagation in the intact endothelium is unresolved. EXPERIMENTAL APPROACH Precision signal generation and targeted cellular manipulation was used in conjunction with high spatiotemporal mesoscale Ca2+ imaging in the endothelium of intact blood vessels. KEY RESULTS Multiple mechanisms maintain communication so that Ca2+ wave propagation occurs irrespective of the status of connectivity among cells. Between adjoining cells, regenerative IP3-induced IP3 production transmits Ca2+ signals and explains the propagated vasodilation that underlies the increased blood flow accompanying tissue activity. The inositide is itself sufficient to evoke regenerative phospholipase C-dependent Ca2+ waves across coupled cells. None of gap junctions, Ca2+ diffusion or the release of extracellular messengers is required to support this type of intercellular Ca2+ signalling. In contrast, when discontinuities exist between cells, ATP released as a diffusible extracellular messenger transmits Ca2+ signals across the discontinuity and drives propagated vasodilation. CONCLUSION AND IMPLICATIONS These results show that signalling switches underlie endothelial cell-to-cell signal transmission and reveal how communication is maintained in the face of endothelial damage. The findings provide a new framework for understanding wave propagation and cell signalling in the endothelium.
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Affiliation(s)
- Charlotte Buckley
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Matthew D Lee
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Xun Zhang
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Calum Wilson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - John G McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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2
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Inhibition of PI4KIIIα as a Novel Potential Approach for Gaucher Disease Treatment. Neurosci Bull 2021; 37:1234-1239. [PMID: 34019252 DOI: 10.1007/s12264-021-00704-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 02/25/2021] [Indexed: 10/21/2022] Open
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3
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Batrouni AG, Baskin JM. The chemistry and biology of phosphatidylinositol 4-phosphate at the plasma membrane. Bioorg Med Chem 2021; 40:116190. [PMID: 33965837 DOI: 10.1016/j.bmc.2021.116190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 12/29/2022]
Abstract
Phosphoinositides are an important class of anionic, low abundance signaling lipids distributed throughout intracellular membranes. The plasma membrane contains three phosphoinositides: PI(4)P, PI(4,5)P2, and PI(3,4,5)P3. Of these, PI(4)P has remained the most mysterious, despite its characterization in this membrane more than a half-century ago. Fortunately, recent methodological innovations at the chemistry-biology interface have spurred a renaissance of interest in PI(4)P. Here, we describe these new toolsets and how they have revealed novel functions for the plasma membrane PI(4)P pool. We examine high-resolution structural characterization of the plasma membrane PI 4-kinase complex that produces PI(4)P, tools for modulating PI(4)P levels including isoform-selective PI 4-kinase inhibitors, and fluorescent probes for visualizing PI(4)P. Collectively, these chemical and biochemical approaches have revealed insights into how cells regulate synthesis of PI(4)P and its downstream metabolites as well as new roles for plasma membrane PI(4)P in non-vesicular lipid transport, membrane homeostasis and trafficking, and cell signaling pathways.
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Affiliation(s)
- Alex G Batrouni
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jeremy M Baskin
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.
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4
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Tian S, Zeng J, Liu X, Chen J, Zhang JZH, Zhu T. Understanding the selectivity of inhibitors toward PI4KIIIα and PI4KIIIβ based molecular modeling. Phys Chem Chem Phys 2019; 21:22103-22112. [DOI: 10.1039/c9cp03598b] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Molecular dynamics simulations and binding free energy calculations are combined to investigate the selectivity of inhibitors toward type III phosphatidylinositol 4 kinases.
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Affiliation(s)
- Shuaizhen Tian
- Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai
- China
| | - Jinzhe Zeng
- Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai
- China
| | - Xiao Liu
- School of Mathematics, Physics and Statistics
- Shanghai University of Engineering Science
- Shanghai 201620
- China
| | - Jianzhong Chen
- School of Science
- Shandong Jiaotong University
- Jinan 250357
- China
| | - John Z. H. Zhang
- Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai
- China
| | - Tong Zhu
- Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai
- China
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5
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Abstract
Plasma membrane (PM) phosphoinositides play essential roles in cell physiology, serving as both markers of membrane identity and signaling molecules central to the cell's interaction with its environment. The first step in PM phosphoinositide synthesis is the conversion of phosphatidylinositol (PI) to PI4P, the precursor of PI(4,5)P2 and PI(3,4,5)P3 This conversion is catalyzed by the PI4KIIIα complex, comprising a lipid kinase, PI4KIIIα, and two regulatory subunits, TTC7 and FAM126. We here report the structure of this complex at 3.6-Å resolution, determined by cryo-electron microscopy. The proteins form an obligate ∼700-kDa superassembly with a broad surface suitable for membrane interaction, toward which the kinase active sites are oriented. The structural complexity of the assembly highlights PI4P synthesis as a major regulatory junction in PM phosphoinositide homeostasis. Our studies provide a framework for further exploring the mechanisms underlying PM phosphoinositide regulation.
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6
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Enterovirus 3A Facilitates Viral Replication by Promoting Phosphatidylinositol 4-Kinase IIIβ-ACBD3 Interaction. J Virol 2017; 91:JVI.00791-17. [PMID: 28701404 DOI: 10.1128/jvi.00791-17] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/05/2017] [Indexed: 01/27/2023] Open
Abstract
Like other enteroviruses, enterovirus 71 (EV71) relies on phosphatidylinositol 4-kinase IIIβ (PI4KB) for genome RNA replication. However, how PI4KB is recruited to the genome replication sites of EV71 remains elusive. Recently, we reported that a host factor, ACBD3, is needed for EV71 replication by interacting with viral 3A protein. Here, we show that ACBD3 is required for the recruitment of PI4KB to RNA replication sites. Overexpression of viral 3A or EV71 infection stimulates the interaction of PI4KB and ACBD3. Consistently, EV71 infection induces the production of phosphatidylinositol-4-phosphate (PI4P). Furthermore, PI4KB, ACBD3, and 3A are all localized to the viral-RNA replication sites. Accordingly, PI4KB or ACBD3 depletion by small interfering RNA (siRNA) leads to a reduction in PI4P production after EV71 infection. I44A or H54Y substitution in 3A interrupts the stimulation of PI4KB and ACBD3. Further analysis suggests that stimulation of ACBD3-PI4KB interaction is also important for the replication of enterovirus 68 but disadvantageous to human rhinovirus 16. These results reveal a mechanism of enterovirus replication that involves a selective strategy for recruitment of PI4KB to the RNA replication sites.IMPORTANCE Enterovirus 71, like other human enteroviruses, replicates its genome within host cells, where viral proteins efficiently utilize cellular machineries. While multiple factors are involved, it is largely unclear how viral replication is controlled. We show that the 3A protein of enterovirus 71 recruits an enzyme, phosphatidylinositol 4-kinase IIIβ, by interacting with ACBD3, which alters cellular membranes through the production of a lipid, PI4P. Consequently, the viral and host proteins form a large complex that is necessary for RNA synthesis at replication sites. Notably, PI4KB-ACBD3 interaction also differentially mediates the replication of enterovirus 68 and rhinovirus 16. These results provide new insight into the molecular network of enterovirus replication.
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7
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Downregulation of RBO-PI4KIIIα Facilitates Aβ 42 Secretion and Ameliorates Neural Deficits in Aβ 42-Expressing Drosophila. J Neurosci 2017; 37:4928-4941. [PMID: 28424219 DOI: 10.1523/jneurosci.3567-16.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/12/2017] [Accepted: 03/31/2017] [Indexed: 12/25/2022] Open
Abstract
Phosphoinositides and their metabolizing enzymes are involved in Aβ42 metabolism and Alzheimer's disease pathogenesis. In yeast and mammals, Eighty-five requiring 3 (EFR3), whose Drosophila homolog is Rolling Blackout (RBO), forms a plasma membrane-localized protein complex with phosphatidylinositol-4-kinase Type IIIα (PI4KIIIα) and a scaffold protein to tightly control the level of plasmalemmal phosphatidylinositol-4-phosphate (PI4P). Here, we report that RBO binds to Drosophila PI4KIIIα, and that in an Aβ42-expressing Drosophila model, separate genetic reduction of PI4KIIIα and RBO, or pharmacological inhibition of PI4KIIIα ameliorated synaptic transmission deficit, climbing ability decline, premature death, and reduced neuronal accumulation of Aβ42 Moreover, we found that RBO-PI4KIIIa downregulation increased neuronal Aβ42 release and that PI4P facilitated the assembly or oligomerization of Aβ42 in/on liposomes. These results indicate that RBO-PI4KIIIa downregulation facilitates neuronal Aβ42 release and consequently reduces neuronal Aβ42 accumulation likely via decreasing Aβ42 assembly in/on plasma membrane. This study suggests the RBO-PI4KIIIα complex as a potential therapeutic target and PI4KIIIα inhibitors as drug candidates for Alzheimer's disease treatment.SIGNIFICANCE STATEMENT Phosphoinositides and their metabolizing enzymes are involved in Aβ42 metabolism and Alzheimer's disease pathogenesis. Here, in an Aβ42-expressing Drosophila model, we discovered and studied the beneficial role of downregulating RBO or its interacting protein PI4KIIIα-a protein that tightly controls the plasmalemmal level of PI4P-against the defects caused by Aβ42 expression. Mechanistically, RBO-PI4KIIIα downregulation reduced neuronal Aβ42 accumulation, and interestingly increased neuronal Aβ42 release. This study suggests the RBO-PI4KIIIα complex as a novel therapeutic target, and PI4KIIIα inhibitors as new drug candidates.
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8
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Tassini S, Sun L, Lanko K, Crespan E, Langron E, Falchi F, Kissova M, Armijos-Rivera JI, Delang L, Mirabelli C, Neyts J, Pieroni M, Cavalli A, Costantino G, Maga G, Vergani P, Leyssen P, Radi M. Discovery of Multitarget Agents Active as Broad-Spectrum Antivirals and Correctors of Cystic Fibrosis Transmembrane Conductance Regulator for Associated Pulmonary Diseases. J Med Chem 2017; 60:1400-1416. [DOI: 10.1021/acs.jmedchem.6b01521] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Sabrina Tassini
- P4T Group, Dipartimento
di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Viale delle Scienze, 27/A, 43124 Parma, Italy
| | - Liang Sun
- Laboratory
of Virology and Experimental Chemotherapy, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000, Leuven, Belgium
| | - Kristina Lanko
- Laboratory
of Virology and Experimental Chemotherapy, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000, Leuven, Belgium
| | - Emmanuele Crespan
- Istituto di Genetica Molecolare, IGM-CNR, Via Abbiategrasso 207, 27100 Pavia, Italy
| | - Emily Langron
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E
6BT London, U.K
| | - Federico Falchi
- CompuNet, Istituto Italiano di Tecnologia, Via Morego 30, I-16163 Genova, Italy
- Department of Pharmacy
and Biotechnology, University of Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
| | - Miroslava Kissova
- Istituto di Genetica Molecolare, IGM-CNR, Via Abbiategrasso 207, 27100 Pavia, Italy
| | | | - Leen Delang
- Laboratory
of Virology and Experimental Chemotherapy, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000, Leuven, Belgium
| | - Carmen Mirabelli
- Laboratory
of Virology and Experimental Chemotherapy, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000, Leuven, Belgium
| | - Johan Neyts
- Laboratory
of Virology and Experimental Chemotherapy, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000, Leuven, Belgium
| | - Marco Pieroni
- P4T Group, Dipartimento
di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Viale delle Scienze, 27/A, 43124 Parma, Italy
| | - Andrea Cavalli
- CompuNet, Istituto Italiano di Tecnologia, Via Morego 30, I-16163 Genova, Italy
- Department of Pharmacy
and Biotechnology, University of Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
| | - Gabriele Costantino
- P4T Group, Dipartimento
di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Viale delle Scienze, 27/A, 43124 Parma, Italy
| | - Giovanni Maga
- Istituto di Genetica Molecolare, IGM-CNR, Via Abbiategrasso 207, 27100 Pavia, Italy
| | - Paola Vergani
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E
6BT London, U.K
| | - Pieter Leyssen
- Laboratory
of Virology and Experimental Chemotherapy, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000, Leuven, Belgium
| | - Marco Radi
- P4T Group, Dipartimento
di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Viale delle Scienze, 27/A, 43124 Parma, Italy
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9
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Mejdrová I, Chalupská D, Plačková P, Müller C, Šála M, Klíma M, Baumlová A, Hřebabecký H, Procházková E, Dejmek M, Strunin D, Weber J, Lee G, Matoušová M, Mertlíková-Kaiserová H, Ziebuhr J, Birkus G, Boura E, Nencka R. Rational Design of Novel Highly Potent and Selective Phosphatidylinositol 4-Kinase IIIβ (PI4KB) Inhibitors as Broad-Spectrum Antiviral Agents and Tools for Chemical Biology. J Med Chem 2016; 60:100-118. [PMID: 28004945 DOI: 10.1021/acs.jmedchem.6b01465] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Phosphatidylinositol 4-kinase IIIβ (PI4KB) is indispensable for the replication of various positive-sense single stranded RNA viruses, which hijack this cellular enzyme to remodel intracellular membranes of infected cells to set up the functional replication machinery. Therefore, the inhibition of this PI4K isoform leads to the arrest of viral replication. Here, we report on the synthesis of novel PI4KB inhibitors, which were rationally designed based on two distinct structural types of inhibitors that bind in the ATP binding side of PI4KB. These "hybrids" not only excel in outstanding inhibitory activity but also show high selectivity to PI4KB compared to other kinases. Thus, these compounds exert selective nanomolar or even subnanomolar activity against PI4KB as well as profound antiviral effect against hepatitis C virus, human rhinovirus, and coxsackievirus B3. Our crystallographic analysis unveiled the exact position of the side chains and explains their extensive contribution to the inhibitory activity.
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Affiliation(s)
- Ivana Mejdrová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.,Department of Chemistry of Natural Compounds, Institute of Chemical Technology Prague , Technická 5, Prague 166 28, Czech Republic
| | - Dominika Chalupská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Pavla Plačková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Christin Müller
- Institute of Medical Virology, Justus Liebig University Giessen , Schubertstrasse 81, D-35392 Giessen, Germany
| | - Michal Šála
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Martin Klíma
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Adriana Baumlová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Hubert Hřebabecký
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Eliška Procházková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Milan Dejmek
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Dmytro Strunin
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Jan Weber
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Gary Lee
- Department of Chemistry of Natural Compounds, Institute of Chemical Technology Prague , Technická 5, Prague 166 28, Czech Republic
| | - Marika Matoušová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Helena Mertlíková-Kaiserová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - John Ziebuhr
- Institute of Medical Virology, Justus Liebig University Giessen , Schubertstrasse 81, D-35392 Giessen, Germany
| | - Gabriel Birkus
- Gilead Sciences, Inc. , 333 Lakeside Drive, Foster City, California 94404, United States
| | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Radim Nencka
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Gilead Sciences & IOCB Research Centre , Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
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10
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Berryman S, Moffat K, Harak C, Lohmann V, Jackson T. Foot-and-mouth disease virus replicates independently of phosphatidylinositol 4-phosphate and type III phosphatidylinositol 4-kinases. J Gen Virol 2016; 97:1841-1852. [PMID: 27093462 PMCID: PMC5156328 DOI: 10.1099/jgv.0.000485] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Picornaviruses form replication complexes in association with membranes in structures called replication organelles. Common themes to emerge from studies of picornavirus replication are the need for cholesterol and phosphatidylinositol 4-phosphate (PI4P). In infected cells, type III phosphatidylinositol 4-kinases (PI4KIIIs) generate elevated levels of PI4P, which is then exchanged for cholesterol at replication organelles. For the enteroviruses, replication organelles form at Golgi membranes in a process that utilizes PI4KIIIβ. Other picornaviruses, for example the cardioviruses, are believed to initiate replication at the endoplasmic reticulum and subvert PI4KIIIα to generate PI4P. Here we investigated the role of PI4KIII in foot-and-mouth disease virus (FMDV) replication. Our results showed that, in contrast to the enteroviruses and the cardioviruses, FMDV replication does not require PI4KIII (PI4KIIIα and PI4KIIIβ), and PI4P levels do not increase in FMDV-infected cells and PI4P is not seen at replication organelles. These results point to a unique requirement towards lipids at the FMDV replication membranes.
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Affiliation(s)
- Stephen Berryman
- The Pirbright Institute, Ash Rd, Pirbright, Surrey, GU24 0NF, UK
| | - Katy Moffat
- The Pirbright Institute, Ash Rd, Pirbright, Surrey, GU24 0NF, UK
| | - Christian Harak
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Terry Jackson
- The Pirbright Institute, Ash Rd, Pirbright, Surrey, GU24 0NF, UK
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11
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Lenz-Majewski mutations in PTDSS1 affect phosphatidylinositol 4-phosphate metabolism at ER-PM and ER-Golgi junctions. Proc Natl Acad Sci U S A 2016; 113:4314-9. [PMID: 27044099 DOI: 10.1073/pnas.1525719113] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Lenz-Majewski syndrome (LMS) is a rare disease characterized by complex craniofacial, dental, cutaneous, and limb abnormalities combined with intellectual disability. Mutations in thePTDSS1gene coding one of the phosphatidylserine (PS) synthase enzymes, PSS1, were described as causative in LMS patients. Such mutations render PSS1 insensitive to feedback inhibition by PS levels. Here we show that expression of mutant PSS1 enzymes decreased phosphatidylinositol 4-phosphate (PI4P) levels both in the Golgi and the plasma membrane (PM) by activating the Sac1 phosphatase and altered PI4P cycling at the PM. Conversely, inhibitors of PI4KA, the enzyme that makes PI4P in the PM, blocked PS synthesis and reduced PS levels by 50% in normal cells. However, mutant PSS1 enzymes alleviated the PI4P dependence of PS synthesis. Oxysterol-binding protein-related protein 8, which was recently identified as a PI4P-PS exchanger between the ER and PM, showed PI4P-dependent membrane association that was significantly decreased by expression of PSS1 mutant enzymes. Our studies reveal that PS synthesis is tightly coupled to PI4P-dependent PS transport from the ER. Consequently, PSS1 mutations not only affect cellular PS levels and distribution but also lead to a more complex imbalance in lipid homeostasis by disturbing PI4P metabolism.
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12
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Boura E, Nencka R. Phosphatidylinositol 4-kinases: Function, structure, and inhibition. Exp Cell Res 2015; 337:136-45. [DOI: 10.1016/j.yexcr.2015.03.028] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 03/12/2015] [Indexed: 02/07/2023]
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13
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Pagnamenta AT, Howard MF, Wisniewski E, Popitsch N, Knight SJL, Keays DA, Quaghebeur G, Cox H, Cox P, Balla T, Taylor JC, Kini U. Germline recessive mutations in PI4KA are associated with perisylvian polymicrogyria, cerebellar hypoplasia and arthrogryposis. Hum Mol Genet 2015; 24:3732-41. [PMID: 25855803 PMCID: PMC4459391 DOI: 10.1093/hmg/ddv117] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 04/03/2015] [Indexed: 01/06/2023] Open
Abstract
Polymicrogyria (PMG) is a structural brain abnormality involving the cerebral cortex that results from impaired neuronal migration and although several genes have been implicated, many cases remain unsolved. In this study, exome sequencing in a family where three fetuses had all been diagnosed with PMG and cerebellar hypoplasia allowed us to identify regions of the genome for which both chromosomes were shared identical-by-descent, reducing the search space for causative variants to 8.6% of the genome. In these regions, the only plausibly pathogenic mutations were compound heterozygous variants in PI4KA, which Sanger sequencing confirmed segregated consistent with autosomal recessive inheritance. The paternally transmitted variant predicted a premature stop mutation (c.2386C>T; p.R796X), whereas the maternally transmitted variant predicted a missense substitution (c.5560G>A; p.D1854N) at a conserved residue within the catalytic domain. Functional studies using expressed wild-type or mutant PI4KA enzyme confirmed the importance of p.D1854 for kinase activity. Our results emphasize the importance of phosphoinositide signalling in early brain development.
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Affiliation(s)
- Alistair T Pagnamenta
- National Institute for Health Research Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Malcolm F Howard
- National Institute for Health Research Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Eva Wisniewski
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, MD 20892, USA
| | - Niko Popitsch
- National Institute for Health Research Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Samantha J L Knight
- National Institute for Health Research Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - David A Keays
- Institute of Molecular Pathology, Vienna 1030, Austria
| | | | - Helen Cox
- West Midlands Regional Clinical Genetics Service, Clinical Genetics Unit and
| | - Phillip Cox
- Department of Histopathology, Birmingham Women's Hospital NHS Foundation Trust, Birmingham B15 2TG, UK
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jenny C Taylor
- National Institute for Health Research Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Usha Kini
- Department of Clinical Genetics, Oxford University Hospitals NHS Trust, Oxford OX3 9DU, UK,
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Burke JE, Inglis AJ, Perisic O, Masson GR, McLaughlin SH, Rutaganira F, Shokat KM, Williams RL. Structures of PI4KIIIβ complexes show simultaneous recruitment of Rab11 and its effectors. Science 2014; 344:1035-8. [PMID: 24876499 DOI: 10.1126/science.1253397] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Phosphatidylinositol 4-kinases (PI4Ks) and small guanosine triphosphatases (GTPases) are essential for processes that require expansion and remodeling of phosphatidylinositol 4-phosphate (PI4P)-containing membranes, including cytokinesis, intracellular development of malarial pathogens, and replication of a wide range of RNA viruses. However, the structural basis for coordination of PI4K, GTPases, and their effectors is unknown. Here, we describe structures of PI4Kβ (PI4KIIIβ) bound to the small GTPase Rab11a without and with the Rab11 effector protein FIP3. The Rab11-PI4KIIIβ interface is distinct compared with known structures of Rab complexes and does not involve switch regions used by GTPase effectors. Our data provide a mechanism for how PI4KIIIβ coordinates Rab11 and its effectors on PI4P-enriched membranes and also provide strategies for the design of specific inhibitors that could potentially target plasmodial PI4KIIIβ to combat malaria.
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Affiliation(s)
- John E Burke
- Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
| | - Alison J Inglis
- Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Olga Perisic
- Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Glenn R Masson
- Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Stephen H McLaughlin
- Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Florentine Rutaganira
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco (UCSF), San Francisco, CA 94158, USA
| | - Kevan M Shokat
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco (UCSF), San Francisco, CA 94158, USA
| | - Roger L Williams
- Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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15
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Hammond GRV, Machner MP, Balla T. A novel probe for phosphatidylinositol 4-phosphate reveals multiple pools beyond the Golgi. ACTA ACUST UNITED AC 2014; 205:113-26. [PMID: 24711504 PMCID: PMC3987136 DOI: 10.1083/jcb.201312072] [Citation(s) in RCA: 466] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Characterization of a new biosensor for PtdIns4P reveals a wider cellular distribution for the polyphosphoinositide than the Golgi localization reported previously, including pools in both the plasma membrane and late endosomes/lysosomes. Polyphosphoinositides are an important class of lipid that recruit specific effector proteins to organelle membranes. One member, phosphatidylinositol 4-phosphate (PtdIns4P) has been localized to Golgi membranes based on the distribution of lipid binding modules from PtdIns4P effector proteins. However, these probes may be biased by additional interactions with other Golgi-specific determinants. In this paper, we derive a new PtdIns4P biosensor using the PtdIns4P binding of SidM (P4M) domain of the secreted effector protein SidM from the bacterial pathogen Legionella pneumophila. PtdIns4P was necessary and sufficient for localization of P4M, which revealed pools of the lipid associated not only with the Golgi but also with the plasma membrane and Rab7-positive late endosomes/lysosomes. PtdIns4P distribution was determined by the localization and activities of both its anabolic and catabolic enzymes. Therefore, P4M reports a wider cellular distribution of PtdIns4P than previous probes and therefore will be valuable for dissecting the biological functions of PtdIns4P in its assorted membrane compartments.
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Affiliation(s)
- Gerald R V Hammond
- Program in Developmental Neuroscience and 2 Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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16
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The resistance tetrad: amino acid hotspots for kinome-wide exploitation of drug-resistant protein kinase alleles. Methods Enzymol 2014; 548:117-46. [PMID: 25399644 DOI: 10.1016/b978-0-12-397918-6.00005-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Acquired resistance to targeted kinase inhibitors is a well-documented clinical problem that is potentially fatal for patients to whom a suitable back-up is not available. However, protein kinase alleles that promote resistance to inhibitors can be exploited experimentally as gold-standards for "on"- and "off"-target validation strategies and constitute a powerful resource for assessing the ability of new or combined therapies to override resistance. Clinical resistance to kinase inhibitors is an evident in all tyrosine kinase-driven malignancies, where high rates of mutation drive tumor evolution toward the insidious drug-resistant (DR) state through a variety of mechanisms. Unfortunately, this problem is likely to intensify in the future as the number of target kinases, approved inhibitors, and clinical indications increase. To empower the analysis of resistance in kinases, we have validated a bioinformatic, structural, and cellular workflow for designing and evaluating resistance at key mutational hotspots among kinome members. In this chapter, we discuss how mutation of amino acids in the gatekeeper and hinge-loop regions (collectively termed the "resistance tetrad") and the DFG motif represent an effective approach for generating panels of DR kinase alleles for chemical genetics and biological target validation.
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van der Schaar HM, Leyssen P, Thibaut HJ, de Palma A, van der Linden L, Lanke KHW, Lacroix C, Verbeken E, Conrath K, MacLeod AM, Mitchell DR, Palmer NJ, van de Poël H, Andrews M, Neyts J, van Kuppeveld FJM. A novel, broad-spectrum inhibitor of enterovirus replication that targets host cell factor phosphatidylinositol 4-kinase IIIβ. Antimicrob Agents Chemother 2013; 57:4971-81. [PMID: 23896472 PMCID: PMC3811463 DOI: 10.1128/aac.01175-13] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 07/19/2013] [Indexed: 12/22/2022] Open
Abstract
Despite their high clinical and socioeconomic impacts, there is currently no approved antiviral therapy for the prophylaxis or treatment of enterovirus infections. Here we report on a novel inhibitor of enterovirus replication, compound 1, 2-fluoro-4-(2-methyl-8-(3-(methylsulfonyl)benzylamino)imidazo[1,2-a]pyrazin-3-yl)phenol. This compound exhibited a broad spectrum of antiviral activity, as it inhibited all tested species of enteroviruses and rhinoviruses, with 50% effective concentrations ranging between 4 and 71 nM. After a lengthy resistance selection process, coxsackievirus mutants resistant to compound 1 were isolated that carried substitutions in their 3A protein. Remarkably, the same substitutions were recently shown to provide resistance to inhibitors of phosphatidylinositol 4-kinase IIIβ (PI4KIIIβ), a lipid kinase that is essential for enterovirus replication, suggesting that compound 1 may also target this host factor. Accordingly, compound 1 directly inhibited PI4KIIIβ in an in vitro kinase activity assay. Furthermore, the compound strongly reduced the PI 4-phosphate levels of the Golgi complex in cells. Rescue of coxsackievirus replication in the presence of compound 1 by a mutant PI4KIIIβ carrying a substitution in its ATP-binding pocket revealed that the compound directly binds the kinase at this site. Finally, we determined that an analogue of compound 1, 3-(3-fluoro-4-methoxyphenyl)-2-methyl-N-(pyridin-4-ylmethyl)imidazo[1,2-a]pyrazin-8-amine, is well tolerated in mice and has a dose-dependent protective activity in a coxsackievirus serotype B4-induced pancreatitis model.
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Affiliation(s)
- Hilde M. van der Schaar
- Department of Infectious Diseases and Immunology, Virology Division, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Pieter Leyssen
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Hendrik J. Thibaut
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Armando de Palma
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Lonneke van der Linden
- Department of Medical Microbiology, Nijmegen Centre for Molecular Life Sciences, and Nijmegen Institute for Infection, Inflammation and Immunity, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Kjerstin H. W. Lanke
- Department of Medical Microbiology, Nijmegen Centre for Molecular Life Sciences, and Nijmegen Institute for Infection, Inflammation and Immunity, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Céline Lacroix
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Erik Verbeken
- Translational Cell & Tissue Research, Department of Imaging & Pathology, University of Leuven, Leuven, Belgium
| | | | | | | | | | | | | | - Johan Neyts
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Frank J. M. van Kuppeveld
- Department of Infectious Diseases and Immunology, Virology Division, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
- Department of Medical Microbiology, Nijmegen Centre for Molecular Life Sciences, and Nijmegen Institute for Infection, Inflammation and Immunity, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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18
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Phosphatidylinositol 4-Kinases and PI4P Metabolism in the Nervous System: Roles in Psychiatric and Neurological Diseases. Mol Neurobiol 2012; 47:361-72. [DOI: 10.1007/s12035-012-8358-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 09/27/2012] [Indexed: 01/18/2023]
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Coxsackievirus mutants that can bypass host factor PI4KIIIβ and the need for high levels of PI4P lipids for replication. Cell Res 2012; 22:1576-92. [PMID: 22945356 DOI: 10.1038/cr.2012.129] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RNA viruses can rapidly mutate and acquire resistance to drugs that directly target viral enzymes, which poses serious problems in a clinical context. Therefore, there is a growing interest in the development of antiviral drugs that target host factors critical for viral replication, since they are unlikely to mutate in response to therapy. We recently demonstrated that phosphatidylinositol-4-kinase IIIβ (PI4KIIIβ) and its product phosphatidylinositol-4-phosphate (PI4P) are essential for replication of enteroviruses, a group of medically important RNA viruses including poliovirus (PV), coxsackievirus, rhinovirus, and enterovirus 71. Here, we show that enviroxime and GW5074 decreased PI4P levels at the Golgi complex by directly inhibiting PI4KIIIβ. Coxsackievirus mutants resistant to these inhibitors harbor single point mutations in the non-structural protein 3A. These 3A mutations did not confer compound-resistance by restoring the activity of PI4KIIIβ in the presence of the compounds. Instead, replication of the mutant viruses no longer depended on PI4KIIIβ, since their replication was insensitive to siRNA-mediated depletion of PI4KIIIβ. The mutant viruses also did not rely on other isoforms of PI4K. Consistently, no high level of PI4P could be detected at the replication sites induced by the mutant viruses in the presence of the compounds. Collectively, these findings indicate that through specific single point mutations in 3A, CVB3 can bypass an essential host factor and lipid for its propagation, which is a new example of RNA viruses acquiring resistance against antiviral compounds, even when they directly target host factors.
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20
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Delage E, Ruelland E, Zachowski A, Puyaubert J. Eat in or take away? How phosphatidylinositol 4-kinases feed the phospholipase C pathway with substrate. PLANT SIGNALING & BEHAVIOR 2012; 7:1197-9. [PMID: 22899063 PMCID: PMC3489660 DOI: 10.4161/psb.21305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Phosphatidylinositol 4-kinases (PI4Ks) catalyze the first step in the synthesis of phosphoinositide pools hydrolysed by phosphoinositide-dependent phospholipase C (PI-PLC) and thus constitute a potential key regulation point of this pathway. Twelve putative PI4K isoforms, divided as type-II (AtPI4KIIγ1- 8) and type-III PI4Ks (AtPI4KIIIα1- 2 and AtPI4KIIIβ1- 2), have been identified in Arabidopsis genome. By a combination of pharmalogical and genetic approaches we recently evidenced that AtPI4KIIIβ1 and AtPI4KIIIβ2 contribute to supply PI-PLC with substrate and that AtPI4KIIIα1 is probably also involved in this process. Given the current knowledge on PI-PLC and type-III PI4Ks localization in plant cells it raises the question whether type-III PI4Ks produce phosphatidylinositol 4-phosphate at the site of its consumption by the PI-PLC pathway. We therefore discuss the spatial organization of substrate supply to PI-PLC in plant cells with reference to recent data evidenced in mammalian cells.
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Affiliation(s)
- Elise Delage
- Université Pierre et Marie Curie (Paris VI); CNRS; EAC7180; UR5 Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
| | - Eric Ruelland
- Université Pierre et Marie Curie (Paris VI); CNRS; EAC7180; UR5 Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
| | - Alain Zachowski
- Université Pierre et Marie Curie (Paris VI); CNRS; EAC7180; UR5 Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
| | - Juliette Puyaubert
- Université Pierre et Marie Curie (Paris VI); CNRS; EAC7180; UR5 Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
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21
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Delang L, Paeshuyse J, Neyts J. The role of phosphatidylinositol 4-kinases and phosphatidylinositol 4-phosphate during viral replication. Biochem Pharmacol 2012; 84:1400-8. [PMID: 22885339 PMCID: PMC7111036 DOI: 10.1016/j.bcp.2012.07.034] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 07/26/2012] [Accepted: 07/26/2012] [Indexed: 12/20/2022]
Abstract
Phosphoinositides (PI) are phospholipids that mediate signaling cascades in the cell by binding to effector proteins. Reversible phosphorylation of the inositol ring at positions 3, 4 and 5 results in the synthesis of seven different phosphoinositides. Each phosphoinositide has a unique subcellular distribution with a predominant localization in subsets of membranes. These lipids play a major role in recruiting and regulating the function of proteins at membrane interfaces [1]. Several bacteria and viruses modulate and exploit the host PI metabolism to ensure efficient replication and survival. Here, we focus on the roles of cellular phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4-kinases (PI4Ks) during the replication cycle of various viruses. It has been well documented that phosphatidylinositol 4-kinase IIIβ (PI4KIIIβ, EC 2.7.1.67) is indispensable for viral RNA replication of several picornaviruses. Two recruitment strategies were reported: (i) binding and modulation of GBF1/Arf1 to enhance recruitment of PI4KIIIβ and (ii) interaction with ACBD3 for recruitment of PI4KIIIβ. PI4KIII has also been demonstrated to be crucial for hepatitis C virus (HCV) replication. PI4KIII appears to be directly recruited and activated by HCV NS5A protein to the replication complexes. In contrast to picornaviruses, it is still debated whether the α or the β isoform is the most important. PI4KIII can be explored as a target for inhibition of viral replication. The challenge will be to develop highly selective inhibitors for PI4KIIIα and/or β and to avoid off-target toxicity.
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Affiliation(s)
- Leen Delang
- Rega Institute for Medical Research, KU Leuven, Belgium
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22
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Abstract
Phosphatidylinositol 4-phosphate (PtdIns4P) is a quantitatively minor membrane phospholipid which is the precursor of PtdIns(4,5)P (2) in the classical agonist-regulated phospholipase C signalling pathway. However, PtdIns4P also governs the recruitment and function of numerous trafficking molecules, principally in the Golgi complex. The majority of phosphoinositides (PIs) phosphorylated at the D4 position of the inositol headgroup are derived from PtdIns4P and play roles in a diverse array of fundamental cellular processes including secretion, cell migration, apoptosis and mitogenesis; therefore, PtdIns4P biosynthesis can be regarded as key point of regulation in many PI-dependent processes.Two structurally distinct sequence families, the type II and type III PtdIns 4-kinases, are responsible for PtdIns4P synthesis in eukaryotic organisms. These important proteins are differentially expressed, localised and regulated by distinct mechanisms, indicating that the enzymes perform non-redundant roles in trafficking and signalling. In recent years, major advances have been made in our understanding of PtdIns4K biology and here we summarise current knowledge of PtdIns4K structure, function and regulation.
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Affiliation(s)
- Shane Minogue
- Centre for Molecular Cell Biology, Department of Inflammation, Division of Medicine, University College London, Rowland Hill Street, Hampstead, NW3 2PF, London, United Kingdom,
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A drug targeting only p110α can block phosphoinositide 3-kinase signalling and tumour growth in certain cell types. Biochem J 2011; 438:53-62. [PMID: 21668414 PMCID: PMC3174055 DOI: 10.1042/bj20110502] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genetic alterations in PI3K (phosphoinositide 3-kinase) signalling are common in cancer and include deletions in PTEN (phosphatase and tensin homologue deleted on chromosome 10), amplifications of PIK3CA and mutations in two distinct regions of the PIK3CA gene. This suggests drugs targeting PI3K, and p110α in particular, might be useful in treating cancers. Broad-spectrum inhibition of PI3K is effective in preventing growth factor signalling and tumour growth, but suitable inhibitors of p110α have not been available to study the effects of inhibiting this isoform alone. In the present study we characterize a novel small molecule, A66, showing the S-enantiomer to be a highly specific and selective p110α inhibitor. Using molecular modelling and biochemical studies, we explain the basis of this selectivity. Using a panel of isoform-selective inhibitors, we show that insulin signalling to Akt/PKB (protein kinase B) is attenuated by the additive effects of inhibiting p110α/p110β/p110δ in all cell lines tested. However, inhibition of p110α alone was sufficient to block insulin signalling to Akt/PKB in certain cell lines. The responsive cell lines all harboured H1047R mutations in PIK3CA and have high levels of p110α and class-Ia PI3K activity. This may explain the increased sensitivity of these cells to p110α inhibitors. We assessed the activation of Akt/PKB and tumour growth in xenograft models and found that tumours derived from two of the responsive cell lines were also responsive to A66 in vivo. These results show that inhibition of p110α alone has the potential to block growth factor signalling and reduce growth in a subset of tumours.
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Zakharian E, Cao C, Rohacs T. Intracellular ATP supports TRPV6 activity via lipid kinases and the generation of PtdIns(4,5) P₂. FASEB J 2011; 25:3915-28. [PMID: 21810903 DOI: 10.1096/fj.11-184630] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Transient receptor potential vanilloid 6 (TRPV6) channels play an important role in Ca(2+) absorption in the intestines. Both phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] and cytoplasmic ATP have been proposed to be important for maintaining TRPV6 activity. To evaluate whether PtdIns(4,5)P(2) and ATP affect channel activity directly or indirectly, we have used a dual approach, examining channel activity in excised patches and planar lipid bilayers. In excised inside-out patch-clamp measurements, ATP reactivated the human TRPV6 channels after current rundown only in the presence of Mg(2+). The effect of MgATP was inhibited by 3 structurally different compounds that inhibit type III phosphatidylinositol 4-kinases (PI4Ks). PtdIns(4,5)P(2) also activated TRPV6 in excised patches, while its precursor PtdIns(4)P had only minimal effect. These data demonstrate that MgATP provides substrate for lipid kinases, allowing the resynthesis of PtdIns(4,5)P(2). To determine whether PtdIns(4,5)P(2) is a direct activator of TRPV6, we purified and reconstituted the channel protein in planar lipid bilayers. The reconstituted channel showed high activity in the presence of PtdIns(4,5)P(2), while PtdIns(4)P induced only minimal activity. Our data establish PtdIns(4,5)P(2) as a direct activator of TRPV6 and demonstrate that intracellular ATP regulates the channel indirectly as a substrate for type III PI4Ks.
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Affiliation(s)
- Eleonora Zakharian
- University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
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Tai AW, Bojjireddy N, Balla T. A homogeneous and nonisotopic assay for phosphatidylinositol 4-kinases. Anal Biochem 2011; 417:97-102. [PMID: 21704602 DOI: 10.1016/j.ab.2011.05.046] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/25/2011] [Accepted: 05/31/2011] [Indexed: 11/25/2022]
Abstract
Phosphatidylinositol 4-kinases (PI 4-kinases) catalyze the conversion of phosphatidylinositol to phosphatidylinositol 4-phosphate (PtdIns4P). The four known mammalian PI 4-kinases, PI4KA, PI4KB, PI4K2A, and PI4K2B have roles in intracellular lipid and protein trafficking. PI4KA and PI4KB also assist in the replication of several positive-sense RNA viruses. The identification of selective inhibitors of these kinases would be facilitated by assays suitable for high-throughput screening. We describe a homogeneous and nonisotopic assay for PI 4-kinase activity based on the bioluminescent detection of the ADP produced by kinase reactions. We have evaluated this assay with known nonselective inhibitors of PI 4-kinases and show that it performs similar to radiometric assay formats previously described in the literature. In addition, this assay generates Z-factor values of >0.7 for PI4KA in a 384-well format, demonstrating its suitability for high-throughput screening applications.
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Affiliation(s)
- Andrew W Tai
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA.
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26
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Abstract
The PI3-K family is one of the most intensely pursued classes of drug targets. This chapter reviews some of the chemical and structural features that determine the selectivity of PI3-K inhibitors, by focusing on a few key compounds that have been instrumental in guiding our understanding of how to design drugs against this family.
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27
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Ma H, Blake T, Chitnis A, Liu P, Balla T. Crucial role of phosphatidylinositol 4-kinase IIIalpha in development of zebrafish pectoral fin is linked to phosphoinositide 3-kinase and FGF signaling. J Cell Sci 2009; 122:4303-10. [PMID: 19887586 DOI: 10.1242/jcs.057646] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Phosphatidylinositol 4-kinases (PI4Ks) catalyze the first committed step in the synthesis of phosphoinositides, important lipid regulators of signaling and trafficking pathways. Here we cloned Pik4a, one of the zebrafish PI4K enzymes, and studied its role(s) in vertebrate development using morpholino oligonucleotide-based gene silencing in zebrafish. Downregulation of Pik4a led to multiple developmental abnormalities, affecting the brain, heart, trunk and most prominently causing loss of pectoral fins. Strikingly similar defects were caused by treatment of the developing embryos with the phosphoinositide 3-kinase (PI3K) inhibitor, LY294002. To investigate the cause of the pectoral fin developmental defect, we focused on fibroblast growth factor (FGF) signaling pathways because vertebrate limb development requires the concerted action of a series of FGF ligands. Using in situ hybridization, the pectoral fin defect was traced to disruption of the early FGF signaling loops that are crucial for the establishment of the sharp signaling center formed by the apical ectodermal ridge and the underlying mesenchyme. This, in turn caused a prominent loss of the induction of one of the mitogen-activated protein kinase (MAPK) phosphatases, Mkp3, an essential intermediate in vertebrate limb development. These changes were associated with impaired proliferation in the developing fin bud due to a loss of balance between the MAPK and PI3K branch of FGF-initiated signals. Our results identify Pik4a as an upstream partner of PI3Ks in the signaling cascade orchestrated by FGF receptors with a prominent role in forelimb development.
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Affiliation(s)
- Hui Ma
- Section on Molecular Signal Transduction, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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28
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Wang Z, Martin J, Abubucker S, Yin Y, Gasser RB, Mitreva M. Systematic analysis of insertions and deletions specific to nematode proteins and their proposed functional and evolutionary relevance. BMC Evol Biol 2009; 9:23. [PMID: 19175938 PMCID: PMC2644674 DOI: 10.1186/1471-2148-9-23] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 01/28/2009] [Indexed: 11/25/2022] Open
Abstract
Background Amino acid insertions and deletions in proteins are considered relatively rare events, and their associations with the evolution and adaptation of organisms are not yet understood. In this study, we undertook a systematic analysis of over 214,000 polypeptides from 32 nematode species and identified insertions and deletions unique to nematode proteins in more than 1000 families and provided indirect evidence that these alterations are linked to the evolution and adaptation of nematodes. Results Amino acid alterations in sequences of nematodes were identified by comparison with homologous sequences from a wide range of eukaryotic (metzoan) organisms. This comparison revealed that the proteins inferred from transcriptomic datasets for nematodes contained more deletions than insertions, and that the deletions tended to be larger in length than insertions, indicating a decreased size of the transcriptome of nematodes compared with other organisms. The present findings showed that this reduction is more pronounced in parasitic nematodes compared with the free-living nematodes of the genus Caenorhabditis. Consistent with a requirement for conservation in proteins involved in the processing of genetic information, fewer insertions and deletions were detected in such proteins. On the other hand, more insertions and deletions were recorded for proteins inferred to be involved in the endocrine and immune systems, suggesting a link with adaptation. Similarly, proteins involved in multiple cellular pathways tended to display more deletions and insertions than those involved in a single pathway. The number of insertions and deletions shared by a range of plant parasitic nematodes were higher for proteins involved in lipid metabolism and electron transport compared with other nematodes, suggesting an association between metabolic adaptation and parasitism in plant hosts. We also identified three sizable deletions from proteins found to be specific to and shared by parasitic nematodes, which, given their uniqueness, might serve as target candidates for drug design. Conclusion This study illustrates the significance of using comparative genomics approaches to identify molecular elements unique to parasitic nematodes, which have adapted to a particular host organism and mode of existence during evolution. While the focus of this study was on nematodes, the approach has applicability to a wide range of other groups of organisms.
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Affiliation(s)
- Zhengyuan Wang
- The Genome Center, Department of Genetics, Washington University School of Medicine, St Louis, MO 63110, USA.
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29
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SHIP prevents lipopolysaccharide from triggering an antiviral response in mice. Blood 2009; 113:2945-54. [PMID: 19139077 DOI: 10.1182/blood-2008-06-166082] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Gram-negative bacterial infections, unlike viral infections, do not typically protect against subsequent viral infections. This is puzzling given that lipopolysaccharide (LPS) and double-stranded (ds) RNA both activate the TIR domain-containing adaptor-inducing interferon beta (TRIF) pathway and, thus, are both capable of eliciting an antiviral response by stimulating type I interferon (IFN) production. We demonstrate herein that SH2-containing inositol-5'-phosphatase (SHIP) protein levels are dramatically increased in murine macrophages via the MyD88-dependent pathway, by up-regulating autocrine-acting transforming growth factor-beta (TGFbeta). The increased SHIP then mediates, via inhibition of the phosphatidylinositol-3-kinase (PI3K) pathway, cytosine-phosphate-guanosine (CPG)- and LPS-induced tolerance and cross-tolerance and restrains IFN-beta production induced by a subsequent exposure to LPS or dsRNA. Intriguingly, we found, using isoform-specific PI3K inhibitors, that LPS- or cytosine-phosphate-guanosine-induced interleukin-6 (IL-6) is positively regulated by p110alpha, -gamma, and -delta but negatively regulated by p110beta. This may explain some of the controversy concerning the role of PI3K in Toll-like receptor-induced cytokine production. Consistent with our in vitro findings, SHIP(-/-) mice overproduce IFN-beta in response to LPS, and this leads to antiviral hypothermia. Thus, up-regulation of SHIP in response to Gram-negative bacterial infections probably explains the inability of such infections to protect against subsequent viral infections.
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Zunder ER, Knight ZA, Houseman BT, Apsel B, Shokat KM. Discovery of drug-resistant and drug-sensitizing mutations in the oncogenic PI3K isoform p110 alpha. Cancer Cell 2008; 14:180-92. [PMID: 18691552 PMCID: PMC2720137 DOI: 10.1016/j.ccr.2008.06.014] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 05/19/2008] [Accepted: 06/25/2008] [Indexed: 11/27/2022]
Abstract
p110 alpha (PIK3CA) is the most frequently mutated kinase in human cancer, and numerous drugs targeting this kinase are currently in preclinical development or early-stage clinical trials. Clinical resistance to protein kinase inhibitors frequently results from point mutations that block drug binding; similar mutations in p110 alpha are likely, but currently none have been reported. Using a S. cerevisiae screen against a structurally diverse panel of PI3K inhibitors, we have identified a potential hotspot for resistance mutations (I800), a drug-sensitizing mutation (L814C), and a surprising lack of resistance mutations at the "gatekeeper" residue. Our analysis further reveals that clinical resistance to these drugs may be attenuated by using multitargeted inhibitors that simultaneously inhibit additional PI3K pathway members.
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Affiliation(s)
- Eli R. Zunder
- Graduate Group in Biophysics, University of California, San Francisco, California 94158
| | - Zachary A. Knight
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021
| | - Benjamin T. Houseman
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94143
| | - Beth Apsel
- Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, CA 94158, USA
| | - Kevan M. Shokat
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94143
- Howard Hughes Medical Institute, University of California, San Francisco, California 94143
- Department of Chemistry, University of California, Berkeley, California 94720
- Correspondence: , phone: 415-514-0472, fax: 415-514-0822
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