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Di Meo D, Kundu T, Ravindran P, Shah B, Püschel AW. Pip5k1γ regulates axon formation by limiting Rap1 activity. Life Sci Alliance 2024; 7:e202302383. [PMID: 38438249 PMCID: PMC10912816 DOI: 10.26508/lsa.202302383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 02/26/2024] [Accepted: 02/26/2024] [Indexed: 03/06/2024] Open
Abstract
During their differentiation, neurons establish a highly polarized morphology by forming axons and dendrites. Cortical and hippocampal neurons initially extend several short neurites that all have the potential to become an axon. One of these neurites is then selected as the axon by a combination of positive and negative feedback signals that promote axon formation and prevent the remaining neurites from developing into axons. Here, we show that Pip5k1γ is required for the formation of a single axon as a negative feedback signal that regulates C3G and Rap1 through the generation of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). Impairing the function of Pip5k1γ results in a hyper-activation of the Fyn/C3G/Rap1 pathway, which induces the formation of supernumerary axons. Application of a hyper-osmotic shock to modulate membrane tension has a similar effect, increasing Rap1 activity and inducing the formation of supernumerary axons. In both cases, the induction of supernumerary axons can be reverted by expressing constitutively active Pip5k. Our results show that PI(4,5)P2-dependent membrane properties limit the activity of C3G and Rap1 to ensure the extension of a single axon.
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Affiliation(s)
- Danila Di Meo
- https://ror.org/00pd74e08 Institut für Integrative Zellbiologie und Physiologie, Universität Münster, Münster, Germany
- https://ror.org/00pd74e08 Cells-in-Motion Interfaculty Center, University of Münster, Münster, Germany
| | - Trisha Kundu
- https://ror.org/00pd74e08 Institut für Integrative Zellbiologie und Physiologie, Universität Münster, Münster, Germany
- https://ror.org/00pd74e08 Cells-in-Motion Interfaculty Center, University of Münster, Münster, Germany
| | - Priyadarshini Ravindran
- https://ror.org/00pd74e08 Institut für Integrative Zellbiologie und Physiologie, Universität Münster, Münster, Germany
| | - Bhavin Shah
- https://ror.org/00pd74e08 Institut für Integrative Zellbiologie und Physiologie, Universität Münster, Münster, Germany
| | - Andreas W Püschel
- https://ror.org/00pd74e08 Institut für Integrative Zellbiologie und Physiologie, Universität Münster, Münster, Germany
- https://ror.org/00pd74e08 Cells-in-Motion Interfaculty Center, University of Münster, Münster, Germany
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2
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Wills RC, Doyle CP, Zewe JP, Pacheco J, Hansen SD, Hammond GRV. A novel homeostatic mechanism tunes PI(4,5)P2-dependent signaling at the plasma membrane. J Cell Sci 2023; 136:jcs261494. [PMID: 37534432 PMCID: PMC10482388 DOI: 10.1242/jcs.261494] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 07/19/2023] [Indexed: 08/04/2023] Open
Abstract
The lipid molecule phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] controls all aspects of plasma membrane (PM) function in animal cells, from its selective permeability to the attachment of the cytoskeleton. Although disruption of PI(4,5)P2 is associated with a wide range of diseases, it remains unclear how cells sense and maintain PI(4,5)P2 levels to support various cell functions. Here, we show that the PIP4K family of enzymes, which synthesize PI(4,5)P2 via a minor pathway, also function as sensors of tonic PI(4,5)P2 levels. PIP4Ks are recruited to the PM by elevated PI(4,5)P2 levels, where they inhibit the major PI(4,5)P2-synthesizing PIP5Ks. Perturbation of this simple homeostatic mechanism reveals differential sensitivity of PI(4,5)P2-dependent signaling to elevated PI(4,5)P2 levels. These findings reveal that a subset of PI(4,5)P2-driven functions might drive disease associated with disrupted PI(4,5)P2 homeostasis.
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Affiliation(s)
- Rachel C. Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Colleen P. Doyle
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - James P. Zewe
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Jonathan Pacheco
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Scott D. Hansen
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403, USA
| | - Gerald R. V. Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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3
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Llorente A, Arora GK, Grenier SF, Emerling BM. PIP kinases: A versatile family that demands further therapeutic attention. Adv Biol Regul 2023; 87:100939. [PMID: 36517396 PMCID: PMC9992244 DOI: 10.1016/j.jbior.2022.100939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022]
Abstract
Phosphoinositides are membrane-localized phospholipids that regulate a plethora of essential cellular processes. These lipid signaling molecules are critical for cell homeostasis and therefore their levels are strictly regulated by the coordinated action of several families of lipid kinases and phosphatases. In this review, we provide a focused perspective on the phosphatidylinositol phosphate kinase (PIPK) family and the three subfamilies that compose it: Type I PIPKs or phosphatidylinositol-4-phosphate 5-kinases (PI4P5Ks), Type II PIPKs or phosphatidylinositol-5-phosphate 4-kinases (PI5P4Ks), and Type III PIPKs or phosphatidylinositol-3-phosphate 5-kinases (PIKfyve). Each subfamily is responsible for catalyzing a hydroxyl phosphorylation on specific phosphoinositide species to generate a double phosphorylated lipid, therefore regulating the levels of both substrate and product. Here, we summarize our current knowledge about the functions and regulation of each PIPK subfamily. Further, we highlight the roles of these kinases in various in vivo genetic models and give an overview of their involvement in multiple pathological conditions. The phosphoinositide field has been long focused on targeting PI3K signaling, but growing evidence suggests that it is time to draw attention to the other phosphoinositide kinases. The discovery of the involvement of PIPKs in the pathogenesis of multiple diseases has prompted substantial efforts to turn these enzymes into pharmacological targets. An increasingly refined knowledge of the biology of PIPKs in a variety of in vitro and in vivo models will facilitate the development of effective approaches for therapeutic intervention with the potential to translate into meaningful clinical benefits for patients suffering from cancer, immunological and infectious diseases, and neurodegenerative disorders.
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Affiliation(s)
- Alicia Llorente
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA
| | - Gurpreet K Arora
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA
| | - Shea F Grenier
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA
| | - Brooke M Emerling
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA.
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4
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Dickson EJ. Role of Lysosomal Cholesterol in Regulating PI(4,5)P 2-Dependent Ion Channel Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:193-215. [PMID: 36988882 DOI: 10.1007/978-3-031-21547-6_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Lysosomes are central regulators of cellular growth and signaling. Once considered the acidic garbage can of the cell, their ever-expanding repertoire of functions include the regulation of cell growth, gene regulation, metabolic signaling, cell migration, and cell death. In this chapter, we detail how another of the lysosome's crucial roles, cholesterol transport, plays a vital role in the control of ion channel function and neuronal excitability through its ability to influence the abundance of the plasma membrane signaling lipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). This chapter will introduce the biosynthetic pathways of cholesterol and PI(4,5)P2, discuss the molecular mechanisms through which each lipid distinctly regulates ion channels, and consider the interdependence of these lipids in the control of ion channel function.
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Affiliation(s)
- Eamonn J Dickson
- Department of Physiology and Membrane Biology, University of California, Davis, CA, USA.
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5
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PI(4,5)P2: signaling the plasma membrane. Biochem J 2022; 479:2311-2325. [PMID: 36367756 PMCID: PMC9704524 DOI: 10.1042/bcj20220445] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 11/13/2022]
Abstract
In the almost 70 years since the first hints of its existence, the phosphoinositide, phosphatidyl-D-myo-inositol 4,5-bisphosphate has been found to be central in the biological regulation of plasma membrane (PM) function. Here, we provide an overview of the signaling, transport and structural roles the lipid plays at the cell surface in animal cells. These include being substrate for second messenger generation, direct modulation of receptors, control of membrane traffic, regulation of ion channels and transporters, and modulation of the cytoskeleton and cell polarity. We conclude by re-evaluating PI(4,5)P2's designation as a signaling molecule, instead proposing a cofactor role, enabling PM-selective function for many proteins.
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6
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Loss of phosphatidylinositol-4-phosphate 5-kinase type-1 gamma (Pip5k1c) in mesenchymal stem cells leads to osteopenia by impairing bone remodeling. J Biol Chem 2022; 298:101639. [PMID: 35090892 PMCID: PMC8867119 DOI: 10.1016/j.jbc.2022.101639] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 01/10/2023] Open
Abstract
Phosphatidylinositol-4-phosphate 5-kinase type-1 gamma (Pip5k1c) is a lipid kinase that plays a pivotal role in the regulation of receptor-mediated calcium signaling in multiple tissues; however, its role in the skeleton is not clear. Here, we show that while deleting Pip5k1c expression in the mesenchymal stem cells using Prx1-Cre transgenic mice does not impair the intramembranous and endochondral ossification during skeletal development, it does cause osteopenia in adult mice, but not rapidly growing young mice. We found Pip5k1c loss dramatically decreases osteoblast formation and osteoid and mineral deposition, leading to reduced bone formation. Furthermore, Pip5k1c loss inhibits osteoblastic, but promotes adipogenic, differentiation of bone marrow stromal cells. Pip5k1c deficiency also impairs cytoplasmic calcium influx and inactivates the calcium/calmodulin-dependent protein kinase, which regulates levels of transcription factor Runx2 by modulating its stability and subsequent osteoblast and bone formation. In addition, Pip5k1c loss reduces levels of the receptor activator of nuclear factor-κB ligand, but not that of osteoprotegerin, its decoy receptor, in osteoblasts in bone and in sera. Finally, we found Pip5k1c loss impairs the ability of bone marrow stromal cells to support osteoclast formation of bone marrow monocytes and reduces the osteoclast precursor population in bone marrow, resulting in reduced osteoclast formation and bone resorption. We conclude Pip5k1c deficiency causes a low-turnover osteopenia in mice, with impairment of bone formation being greater than that of bone resorption. Collectively, we uncover a novel function and mechanism of Pip5k1c in the control of bone mass and identify a potential therapeutic target for osteoporosis.
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7
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Katan M, Cockcroft S. Phosphatidylinositol(4,5)bisphosphate: diverse functions at the plasma membrane. Essays Biochem 2020; 64:513-531. [PMID: 32844214 PMCID: PMC7517351 DOI: 10.1042/ebc20200041] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/25/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022]
Abstract
Phosphatidylinositol(4,5) bisphosphate (PI(4,5)P2) has become a major focus in biochemistry, cell biology and physiology owing to its diverse functions at the plasma membrane. As a result, the functions of PI(4,5)P2 can be explored in two separate and distinct roles - as a substrate for phospholipase C (PLC) and phosphoinositide 3-kinase (PI3K) and as a primary messenger, each having unique properties. Thus PI(4,5)P2 makes contributions in both signal transduction and cellular processes including actin cytoskeleton dynamics, membrane dynamics and ion channel regulation. Signalling through plasma membrane G-protein coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and immune receptors all use PI(4,5)P2 as a substrate to make second messengers. Activation of PI3K generates PI(3,4,5)P3 (phosphatidylinositol(3,4,5)trisphosphate), a lipid that recruits a plethora of proteins with pleckstrin homology (PH) domains to the plasma membrane to regulate multiple aspects of cellular function. In contrast, PLC activation results in the hydrolysis of PI(4,5)P2 to generate the second messengers, diacylglycerol (DAG), an activator of protein kinase C and inositol(1,4,5)trisphosphate (IP3/I(1,4,5)P3) which facilitates an increase in intracellular Ca2+. Decreases in PI(4,5)P2 by PLC also impact on functions that are dependent on the intact lipid and therefore endocytosis, actin dynamics and ion channel regulation are subject to control. Spatial organisation of PI(4,5)P2 in nanodomains at the membrane allows for these multiple processes to occur concurrently.
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Affiliation(s)
- Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Shamshad Cockcroft
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, 21 University Street, London WC1E 6JJ, U.K
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Type I Phosphatidylinositol-4-Phosphate 5-Kinases α and γ Play a Key Role in Targeting HIV-1 Pr55 Gag to the Plasma Membrane. J Virol 2020; 94:JVI.00189-20. [PMID: 32376619 DOI: 10.1128/jvi.00189-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/28/2020] [Indexed: 12/31/2022] Open
Abstract
HIV-1 assembly occurs principally at the plasma membrane (PM) of infected cells. Gag polyprotein precursors (Pr55Gag) are targeted to the PM, and their binding is mediated by the interaction of myristoylated matrix domain and a PM-specific phosphoinositide, the phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2]. The major synthesis pathway of PI(4,5)P2 involves the activity of phosphatidylinositol-4-phosphate 5-kinase family type 1 composed of three isoforms (PIP5K1α, PIP5K1β, and PIP5K1γ). To examine whether the activity of a specific PIP5K1 isoform determines proper Pr55Gag localization at the PM, we compared the cellular behavior of Pr55Gag in the context of PIP5K1 inhibition using siRNAs that individually targeted each of the three isoforms in TZM-bl HeLa cells. We found that downregulation of PIP5K1α and PIP5K1γ strongly impaired the targeting of Pr55Gag to the PM with a rerouting of the polyprotein within intracellular compartments. The efficiency of Pr55Gag release was thus impaired through the silencing of these two isoforms, while PIP5K1β is dispensable for Pr55Gag targeting to the PM. The PM mistargeting due to the silencing of PIP5K1α leads to Pr55Gag hydrolysis through lysosome and proteasome pathways, while the silencing of PIP5K1γ leads to Pr55Gag accumulation in late endosomes. Our findings demonstrated that, within the PIP5K1 family, only the PI(4,5)P2 pools produced by PIP5K1α and PIP5K1γ are involved in the Pr55Gag PM targeting process.IMPORTANCE PM specificity of Pr55Gag membrane binding is mediated through the interaction of PI(4,5)P2 with the matrix (MA) basic residues. It was shown that overexpression of a PI(4,5)P2-depleting enzyme strongly impaired PM localization of Pr55Gag However, cellular factors that control PI(4,5)P2 production required for Pr55Gag-PM targeting have not yet been characterized. In this study, by individually inhibiting PIP5K1 isoforms, we elucidated a correlation between PI(4,5)P2 metabolism pathways mediated by PIP5K1 isoforms and the targeting of Pr55Gag to the PM of TZM-bl HeLa cells. Confocal microscopy analyses of cells depleted from PIP5K1α and PIP5K1γ show a rerouting of Pr55Gag to various intracellular compartments. Notably, Pr55Gag is degraded by the proteasome and/or by the lysosomes in PIP5K1α-depleted cells, while Pr55Gag is targeted to endosomal vesicles in PIP5K1γ-depleted cells. Thus, our results highlight, for the first time, the roles of PIP5K1α and PIP5K1γ as determinants of Pr55Gag targeting to the PM.
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9
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Noch EK, Yim I, Milner TA, Cantley LC. Distribution and localization of phosphatidylinositol 5-phosphate, 4-kinase alpha and beta in the brain. J Comp Neurol 2020; 529:434-449. [PMID: 32449185 DOI: 10.1002/cne.24956] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 05/07/2020] [Accepted: 05/14/2020] [Indexed: 12/14/2022]
Abstract
Phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2 ) is critical for synaptic vesicle docking and fusion and generation of the second messengers, diacylglycerol and inositol-1,4,5-trisphosphate. PI-4,5-P2 can be generated by two families of kinases: type 1 phosphatidylinositol-4-phosphate 5-kinases, encoded by PIP5K1A, PIP5K1B and PIP5K1C, and type 2 phosphatidylinositol-5-phosphate 4-kinases, encoded by PIP4K2A, PIP4K2B, and PIP4K2C. While the roles of the type 1 enzymes in brain function have been extensively studied, the roles of the type 2 enzymes are poorly understood. Using selective antibodies validated by genetic deletion of pip4k2a or pip4k2b in mouse brain, we characterized the location of the enzymes, PI5P4Kα and PI5P4Kβ, encoded by these genes. In mice, we demonstrate that PI5P4Kα is expressed in adulthood, whereas PI5P4Kβ is expressed early in development. PI5P4Kα localizes to white matter tracts, especially the corpus callosum, and at a low level in neurons, while PI5P4Kβ is expressed in neuronal populations, especially hippocampus and cortex. Dual labeling studies demonstrate that PI5P4Kα co-localizes with the oligodendrocyte marker, Olig2, whereas PI5P4Kβ co-localizes with the neuronal marker, NeuN. Ultrastructural analysis demonstrates that both kinases are contained in axon terminals and dendritic spines adjacent to the synaptic membrane, which support a potential role in synaptic transmission. Immunoperoxidase analysis of macaque and human brain tissue demonstrate a conserved pattern for PI5P4Kα and PI5P4Kβ. These results highlight the diverse cell-autonomous expression of PI5P4Kα and PI5P4Kβ and support further exploration into their role in synaptic function in the brain.
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Key Words
- PIP4K
- RRID:AB_1,127,270
- RRID:AB_10,622,025
- RRID:AB_10,711,040
- RRID:AB_1904103
- RRID:AB_2,164,572
- RRID:AB_2,223,210
- RRID:AB_2096811
- RRID:AB_2269374
- RRID:AB_2300649
- RRID:AB_353,929
- RRID:AB_561,049
- brain
- neuron
- oligodendrocyte
- phosphatidylinositol-5-phosphate 4-kinase
- phosphoinositide
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Affiliation(s)
- Evan K Noch
- Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, New York, USA.,Department of Neurology, Weill Cornell Medicine, New York, New York, USA
| | - Isaiah Yim
- Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, New York, USA
| | - Teresa A Milner
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York, USA.,Harold and Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, New York, New York, USA
| | - Lewis C Cantley
- Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, New York, USA
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Nakada-Tsukui K, Watanabe N, Maehama T, Nozaki T. Phosphatidylinositol Kinases and Phosphatases in Entamoeba histolytica. Front Cell Infect Microbiol 2019; 9:150. [PMID: 31245297 PMCID: PMC6563779 DOI: 10.3389/fcimb.2019.00150] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PtdIns) metabolism is indispensable in eukaryotes. Phosphoinositides (PIs) are phosphorylated derivatives of PtdIns and consist of seven species generated by reversible phosphorylation of the inositol moieties at the positions 3, 4, and 5. Each of the seven PIs has a unique subcellular and membrane domain distribution. In the enteric protozoan parasite Entamoeba histolytica, it has been previously shown that the PIs phosphatidylinositol 3-phosphate (PtdIns3P), PtdIns(4,5)P2, and PtdIns(3,4,5)P3 are localized to phagosomes/phagocytic cups, plasma membrane, and phagocytic cups, respectively. The localization of these PIs in E. histolytica is similar to that in mammalian cells, suggesting that PIs have orthologous functions in E. histolytica. In contrast, the conservation of the enzymes that metabolize PIs in this organism has not been well-documented. In this review, we summarized the full repertoire of the PI kinases and PI phosphatases found in E. histolytica via a genome-wide survey of the current genomic information. E. histolytica appears to have 10 PI kinases and 23 PI phosphatases. It has a panel of evolutionarily conserved enzymes that generate all the seven PI species. However, class II PI 3-kinases, type II PI 4-kinases, type III PI 5-phosphatases, and PI 4P-specific phosphatases are not present. Additionally, regulatory subunits of class I PI 3-kinases and type III PI 4-kinases have not been identified. Instead, homologs of class I PI 3-kinases and PTEN, a PI 3-phosphatase, exist as multiple isoforms, which likely reflects that elaborate signaling cascades mediated by PtdIns(3,4,5)P3 are present in this organism. There are several enzymes that have the nuclear localization signal: one phosphatidylinositol phosphate (PIP) kinase, two PI 3-phosphatases, and one PI 5-phosphatase; this suggests that PI metabolism also has conserved roles related to nuclear functions in E. histolytica, as it does in model organisms.
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Affiliation(s)
- Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Natsuki Watanabe
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tomohiko Maehama
- Division of Molecular and Cellular Biology, Graduate School of Medicine, Kobe University, Kobe, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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11
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Baba T, Toth DJ, Sengupta N, Kim YJ, Balla T. Phosphatidylinositol 4,5-bisphosphate controls Rab7 and PLEKHM1 membrane cycling during autophagosome-lysosome fusion. EMBO J 2019; 38:e100312. [PMID: 31368593 PMCID: PMC6463214 DOI: 10.15252/embj.2018100312] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/02/2019] [Accepted: 01/23/2019] [Indexed: 12/12/2022] Open
Abstract
The small GTPase Rab7 is a key organizer of receptor sorting and lysosomal degradation by recruiting of a variety of effectors depending on its GDP/GTP-bound state. However, molecular mechanisms that trigger Rab7 inactivation remain elusive. Here we find that, among the endosomal pools, Rab7-positive compartments possess the highest level of PI4P, which is primarily produced by PI4K2A kinase. Acute conversion of this endosomal PI4P to PI(4,5)P2 causes Rab7 dissociation from late endosomes and releases a regulator of autophagosome-lysosome fusion, PLEKHM1, from the membrane. Rab7 effectors Vps35 and RILP are not affected by acute PI(4,5)P2 production. Deletion of PI4K2A greatly reduces PIP5Kγ-mediated PI(4,5)P2 production in Rab7-positive endosomes leading to impaired Rab7 inactivation and increased number of LC3-positive structures with defective autophagosome-lysosome fusion. These results reveal a late endosomal PI4P-PI(4,5)P2 -dependent regulatory loop that impacts autophagosome flux by affecting Rab7 cycling and PLEKHM1 association.
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Affiliation(s)
- Takashi Baba
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Daniel J Toth
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Nivedita Sengupta
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Yeun Ju Kim
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Tamas Balla
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
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12
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Sharma S, Bhattacharya S, Bhattacharya A. PtdIns(4,5)P 2 is generated by a novel phosphatidylinositol 4-phosphate 5-kinase in the protist parasite Entamoeba histolytica. FEBS J 2019; 286:2216-2234. [PMID: 30843363 DOI: 10.1111/febs.14804] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 02/03/2019] [Accepted: 03/05/2019] [Indexed: 01/02/2023]
Abstract
Entamoeba histolytica is an intestinal protist parasite that causes amoebiasis, a major source of morbidity and mortality in developing countries. Phosphoinositides are involved in signalling systems that have a role in invasion and pathogenesis of this parasite. Phosphatidylinositol 4-phosphate 5-kinase (PIP5K) catalyses the generation of phosphatidylinositol(4,5)bisphosphate (PtdIns(4,5)P2 ), a key species of phosphoinositide that regulates various cellular processes. However, phosphatidylinositol phosphate kinase (PIPK) family of enzymes have not been characterized in E. histolytica. Here, we report the identification and characterization of type I PIPK (EhPIPKI) of E. histolytica. Computational analysis revealed homologs of type I and III PIPK family in E. histolytica and the absence of type II PIPK. In spite of low overall sequence identity, the kinase domain was found to be highly conserved. Interestingly, a unique insertion of a tandem repeat motif was observed in EhPIPKI distinguishing it from existing PIPKs of other organisms. Substrate profiling showed that EhPIPKI could phosphorylate at third and fifth hydroxyl positions of phosphatidylinositols, though the predominant substrate was phosphatidylinositol 4-phosphate (PtdIns(4)P). Furthermore, EhPIPKI underwent intracellular cleavage close to the amino-terminal, generating two distinct fragments Nter-EhPIPKI (27p) and Cter-EhPIPKI (47p). Immunofluorescence and cellular fractionation revealed that the full-length EhPIPKI and the Cter-EhPIPKI containing carboxyl-terminal activation loop were present in the plasma membrane while the Nter-EhPIPKI was observed in the cytosolic region. In conclusion, E. histolytica has a single EhPIPKI gene that displays novel properties of post-translational processing, the presence of a repeat domain and substrate specificity not observed in any PIPK enzyme so far.
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Affiliation(s)
- Shalini Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Sudha Bhattacharya
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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13
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Gq-Coupled Muscarinic Receptor Enhancement of KCNQ2/3 Channels and Activation of TRPC Channels in Multimodal Control of Excitability in Dentate Gyrus Granule Cells. J Neurosci 2018; 39:1566-1587. [PMID: 30593498 DOI: 10.1523/jneurosci.1781-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 12/21/2022] Open
Abstract
KCNQ (Kv7, "M-type") K+ channels and TRPC (transient receptor potential, "canonical") cation channels are coupled to neuronal discharge properties and are regulated via Gq/11-protein-mediated signals. Stimulation of Gq/11-coupled receptors both consumes phosphatidylinositol 4,5-bisphosphate (PIP2) via phosphalipase Cβ hydrolysis and stimulates PIP2 synthesis via rises in Ca2+ i and other signals. Using brain-slice electrophysiology and Ca2+ imaging from male and female mice, we characterized threshold K+ currents in dentate gyrus granule cells (DGGCs) and CA1 pyramidal cells, the effects of Gq/11-coupled muscarinic M1 acetylcholine (M1R) stimulation on M current and on neuronal discharge properties, and elucidated the intracellular signaling mechanisms involved. We observed disparate signaling cascades between DGGCs and CA1 neurons. DGGCs displayed M1R enhancement of M-current, rather than suppression, due to stimulation of PIP2 synthesis, which was paralleled by increased PIP2-gated G-protein coupled inwardly rectifying K+ currents as well. Deficiency of KCNQ2-containing M-channels ablated the M1R-induced enhancement of M-current in DGGCs. Simultaneously, M1R stimulation in DGGCs induced robust increases in [Ca2+]i, mostly due to TRPC currents, consistent with, and contributing to, neuronal depolarization and hyperexcitability. CA1 neurons did not display such multimodal signaling, but rather M current was suppressed by M1R stimulation in these cells, similar to the previously described actions of M1R stimulation on M-current in peripheral ganglia that mostly involves PIP2 depletion. Therefore, these results point to a pleiotropic network of cholinergic signals that direct cell-type-specific, precise control of hippocampal function with strong implications for hyperexcitability and epilepsy.SIGNIFICANCE STATEMENT At the neuronal membrane, protein signaling cascades consisting of ion channels and metabotropic receptors govern the electrical properties and neurotransmission of neuronal networks. Muscarinic acetylcholine receptors are G-protein-coupled metabotropic receptors that control the excitability of neurons through regulating ion channels, intracellular Ca2+ signals, and other second-messenger cascades. We have illuminated previously unknown actions of muscarinic stimulation on the excitability of hippocampal principal neurons that include M channels, TRPC (transient receptor potential, "canonical") cation channels, and powerful regulation of lipid metabolism. Our results show that these signaling pathways, and mechanisms of excitability, are starkly distinct between peripheral ganglia and brain, and even between different principal neurons in the hippocampus.
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Inloes JM, Jing H, Cravatt BF. The Spastic Paraplegia-Associated Phospholipase DDHD1 Is a Primary Brain Phosphatidylinositol Lipase. Biochemistry 2018; 57:5759-5767. [PMID: 30221923 PMCID: PMC6237197 DOI: 10.1021/acs.biochem.8b00810] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Deleterious mutations in the serine hydrolase DDHD domain containing 1 (DDHD1) cause the SPG28 subtype of the neurological disease hereditary spastic paraplegia (HSP), which is characterized by axonal neuropathy and gait impairments. DDHD1 has been shown to display PLA1-type phospholipase activity with a preference for phosphatidic acid. However, the endogenous lipid pathways regulated by DDHD1 in vivo remain poorly understood. Here we use a combination of untargeted and targeted metabolomics to compare the lipid content of brain tissue from DDHD1+/+ and DDHD1-/- mice, revealing that DDHD1 inactivation causes a substantial decrease in the level of polyunsaturated lysophosphatidylinositol (LPI) lipids and a corresponding increase in the level of phosphatidylinositol (PI) lipids. Levels of other phospholipids were mostly unchanged, with the exception of decreases in the levels of select polyunsaturated lysophosphatidylserine (LPS) and lysophosphatidylcholine lipids and a striking remodeling of PI phosphates (e.g., PIP and PIP2) in DDHD1-/- brain tissue. Biochemical assays confirmed that DDHD1 hydrolyzes PI/PS to LPI/LPS with sn-1 selectivity and accounts for a substantial fraction of the PI/PS lipase activity in mouse brain tissue. These data indicate that DDHD1 is a principal regulator of bioactive LPI and other lysophospholipids, as well as PI phosphates, in the mammalian nervous system, pointing to a potential role for these lipid pathways in HSP.
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Affiliation(s)
- Jordon M. Inloes
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Hui Jing
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Benjamin F. Cravatt
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, United States
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15
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Lee JS, Sorcher JL, Rosen AD, Damadzic R, Sun H, Schwandt M, Heilig M, Kelly J, Mauro KL, Luo A, Rosoff D, Muench C, Jung J, Kaminsky ZA, Lohoff FW. Genetic Association and Expression Analyses of the Phosphatidylinositol-4-Phosphate 5-Kinase (PIP5K1C) Gene in Alcohol Use Disorder-Relevance for Pain Signaling and Alcohol Use. Alcohol Clin Exp Res 2018; 42:1034-1043. [PMID: 29667742 PMCID: PMC6134400 DOI: 10.1111/acer.13751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 04/07/2018] [Indexed: 01/07/2023]
Abstract
BACKGROUND The gene encoding phosphatidylinositol-4-phosphate 5-kinase (PIP5K1C) has been recently implicated in pain regulation. Interestingly, a recent cross-tissue and cross-phenotypic epigenetic analysis identified the same gene in alcohol use disorder (AUD). Given the high comorbidity between AUD and chronic pain, we hypothesized that genetic variation in PIP5K1C might contribute to susceptibility to AUD. METHODS We conducted a case-control association study of genetic variants in PIP5K1C. Association analyses of 16 common PIP5K1C single nucleotide polymorphisms (SNPs) were conducted in cases and controls of African (427 cases and 137 controls) and European ancestry (488 cases and 324 controls) using standard methods. In addition, given the prominent role of the opioid system in pain signaling, we investigated the effects of acute alcohol exposure on PIP5K1C expression in humanized transgenic mice for the μ-opioid receptor that included the OPRM1 A118G polymorphism, a widely used mouse model to study analgesic response to opioids in pain. PIP5K1C expression was measured in the thalamus and basolateral amygdala (BLA) in mice after short-term administration (single 2 g/kg dose) of alcohol or saline using immunohistochemistry and analyzed by 2-way analysis of variance. RESULTS In the case-control association study using an NIAAA discovery sample, 8 SNPs in PIP5K1C were significantly associated with AUD in the African ancestry (AA) group (p < 0.05 after correction; rs4807493, rs10405681, rs2074957, rs10432303, rs8109485, rs1476592, rs10419980, and rs4432372). However, a replication analysis using an independent sample (N = 3,801) found no significant associations after correction for multiple testing. In the humanized transgenic mouse model with the OPRM1 polymorphism, PIP5K1C expression was significantly different between alcohol and saline-treated mice, regardless of genotype, in both the thalamus (p < 0.05) and BLA (p < 0.01). CONCLUSIONS Our discovery sample shows that genetic variants in PIP5K1C are associated with AUD in the AA group, and acute alcohol exposure leads to up-regulation of PIP5K1C, potentially explaining a mechanism underlying the increased risk for chronic pain conditions in individuals with AUD.
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Affiliation(s)
- Ji Soo Lee
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Jill L. Sorcher
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Allison D Rosen
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Ruslan Damadzic
- Office of the Clinical Director, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Hui Sun
- Office of the Clinical Director, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Melanie Schwandt
- Office of the Clinical Director, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | | | - John Kelly
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Kelsey L Mauro
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Audrey Luo
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Daniel Rosoff
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Christine Muench
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Jeesun Jung
- Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
| | - Zachary A. Kaminsky
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Falk W. Lohoff
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD
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16
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Olivença DV, Uliyakina I, Fonseca LL, Amaral MD, Voit EO, Pinto FR. A Mathematical Model of the Phosphoinositide Pathway. Sci Rep 2018; 8:3904. [PMID: 29500467 PMCID: PMC5834545 DOI: 10.1038/s41598-018-22226-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 02/19/2018] [Indexed: 01/10/2023] Open
Abstract
Phosphoinositides are signalling lipids that constitute a complex network regulating many cellular processes. We propose a computational model that accounts for all species of phosphoinositides in the plasma membrane of mammalian cells. The model replicates the steady-state of the pathway and most known dynamic phenomena. Sensitivity analysis demonstrates model robustness to alterations in the parameters. Model analysis suggest that the greatest contributor to phosphatidylinositol 4,5-biphosphate (PI(4,5)P2) production is a flux representing the direct transformation of PI into PI(4,5)P2, also responsible for the maintenance of this pool when phosphatidylinositol 4-phosphate (PI(4)P) is decreased. PI(5)P is also shown to be a significant source for PI(4,5)P2 production. The model was validated with siRNA screens that knocked down the expression of enzymes in the pathway. The screen monitored the activity of the epithelium sodium channel (ENaC), which is activated by PI(4,5)P2. While the model may deepen our understanding of other physiological processes involving phosphoinositides, we highlight therapeutic effects of ENaC modulation in Cystic Fibrosis (CF). The model suggests control strategies where the activities of the enzyme phosphoinositide 4-phosphate 5-kinase I (PIP5KI) or the PI4K + PIP5KI + DVL protein complex are decreased and cause an efficacious reduction in PI(4,5)P2 levels while avoiding undesirable alterations in other phosphoinositide pools.
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Affiliation(s)
- Daniel V Olivença
- University of Lisbon, Faculty of Sciences, BIOISI: Biosystems and Integrative Sciences Institute. Campo Grande, 1749-016, Lisbon, Portugal.
| | - Inna Uliyakina
- University of Lisbon, Faculty of Sciences, BIOISI: Biosystems and Integrative Sciences Institute. Campo Grande, 1749-016, Lisbon, Portugal
| | - Luis L Fonseca
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 950 Atlantic Drive, Atlanta, Georgia, 30332-2000, USA
| | - Margarida D Amaral
- University of Lisbon, Faculty of Sciences, BIOISI: Biosystems and Integrative Sciences Institute. Campo Grande, 1749-016, Lisbon, Portugal
| | - Eberhard O Voit
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 950 Atlantic Drive, Atlanta, Georgia, 30332-2000, USA
| | - Francisco R Pinto
- University of Lisbon, Faculty of Sciences, BIOISI: Biosystems and Integrative Sciences Institute. Campo Grande, 1749-016, Lisbon, Portugal
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17
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Nguyen TTN, Seo E, Choi J, Le OTT, Kim JY, Jou I, Lee SY. Phosphatidylinositol 4-phosphate 5-kinase α contributes to Toll-like receptor 2-mediated immune responses in microglial cells stimulated with lipoteichoic acid. Cell Signal 2017; 38:159-170. [DOI: 10.1016/j.cellsig.2017.07.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/21/2017] [Accepted: 07/12/2017] [Indexed: 12/11/2022]
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18
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Barber CN, Huganir RL, Raben DM. Phosphatidic acid-producing enzymes regulating the synaptic vesicle cycle: Role for PLD? Adv Biol Regul 2017; 67:141-147. [PMID: 28986032 DOI: 10.1016/j.jbior.2017.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/25/2017] [Accepted: 09/26/2017] [Indexed: 02/03/2023]
Abstract
In cortical and hippocampal neurons of the mammalian brain, the synaptic vesicle cycle is a series of steps that tightly regulate exo- and endocytosis of vesicles. Many proteins contribute to this regulation, but lipids have recently emerged as critical regulators as well. Of all the many lipid signaling molecules, phosphatidic acid is important to the physical processes of membrane fusion. Therefore, the lipid-metabolizing enzymes that produce phosphatidic acid are vital to the regulation of the cycle. Our lab is particularly interested in the potential regulatory mechanisms and neuronal roles of two phosphatidic acid-producing enzymes: diacylglycerol kinase theta (DGKθ) and phospholipase D (PLD). We recently discovered a regulatory role of DGKθ on evoked endocytosis (Goldschmidt et al., 2016). In addition to this enzyme, studies implicate PLD1 in neurotransmission, although its precise role is of some debate. Altogether, the production of phosphatidic acid by these enzymes offer an interesting and novel pathway for the regulation of the synaptic vesicle cycle.
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Affiliation(s)
- Casey N Barber
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA
| | - Richard L Huganir
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA
| | - Daniel M Raben
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA.
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19
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Abstract
Ptdns(4,5)P2 is a minor structural lipid of the plasma membrane (PM), but a master regulator of PM function. Serving either as a substrate for the generation of second messengers, or more commonly as a ligand triggering protein recruitment or activation, it regulates most aspects of PM function. Understanding how this relatively simple biological macromolecule can regulate such a vast array of different functions in parallel, is the key to understanding the biology of the PM as a whole, in both health and disease. In this review, potential mechanisms are discussed that might explain how a lipid can separately regulate so many protein complexes. The focus is on the spatial distribution of the lipid molecules, their metabolism and their interactions. Open questions that still need to be resolved are highlighted, as are potential experimental approaches that might shed light on the mechanisms at play. Moreover, the broader question is raised as to whether PtdIns(4,5)P2 should be thought of as a bona fide signalling molecule or more of a simple lipid cofactor or perhaps both, depending on the context of the particular function in question.
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20
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Raben DM, Barber CN. Phosphatidic acid and neurotransmission. Adv Biol Regul 2016; 63:15-21. [PMID: 27671966 DOI: 10.1016/j.jbior.2016.09.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/15/2016] [Accepted: 09/19/2016] [Indexed: 12/31/2022]
Abstract
Lipids play a vital role in the health and functioning of neurons and interest in the physiological role of neuronal lipids is certainly increasing. One neuronal function in which neuronal lipids appears to play key roles in neurotransmission. Our understanding of the role of lipids in the synaptic vesicle cycle and neurotransmitter release is becoming increasingly more important. Much of the initial research in this area has highlighted the major roles played by the phosphoinositides (PtdIns), diacylglycerol (DAG), and phosphatidic acid (PtdOH). Of these, PtdOH has not received as much attention as the other lipids although its role and metabolism appears to be extremely important. This lipid has been shown to play a role in modulating both exocytosis and endocytosis although its precise role in either process is not well defined. The currently evidence suggest this lipid likely participates in key processes by altering membrane architecture necessary for membrane fusion, mediating the penetration of membrane proteins, serving as a precursor for other important SV cycling lipids, or activating essential enzymes. In this review, we address the sources of PtdOH, the enzymes involved in its production, the regulation of these enzymes, and its potential roles in neurotransmission in the central nervous system.
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Affiliation(s)
- Daniel M Raben
- The Department of Biological Chemistry, The Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
| | - Casey N Barber
- The Department of Biological Chemistry, The Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
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21
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Abstract
Existing analgesics are not efficacious in treating all patients with chronic pain and have harmful side effects when used long term. A deeper understanding of pain signaling and sensitization could lead to the development of more efficacious analgesics. Nociceptor sensitization occurs under conditions of inflammation and nerve injury where diverse chemicals are released and signal through receptors to reduce the activation threshold of ion channels, leading to an overall increase in neuronal excitability. Drugs that inhibit specific receptors have so far been unsuccessful in alleviating pain, possibly because they do not simultaneously target the diverse receptors that contribute to nociceptor sensitization. Hence, the focus has shifted toward targeting downstream convergence points of nociceptive signaling. Lipid mediators, including phosphatidylinositol 4,5-bisphosphate (PIP2), are attractive targets, as these molecules are required for signaling downstream of G-protein-coupled receptors and receptor tyrosine kinases. Furthermore, PIP2 regulates the activity of various ion channels. Thus, PIP2 sits at a critical convergence point for multiple receptors, ion channels, and signaling pathways that promote and maintain chronic pain. Decreasing the amount of PIP2 in neurons was recently shown to attenuate pronociceptive signaling and could provide a novel approach for treating pain. Here, we review the lipid kinases that are known to regulate pain signaling and sensitization and speculate on which additional lipid kinases might regulate signaling in nociceptive neurons.
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22
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Ando H, Hirose M, Gainche L, Kawaai K, Bonneau B, Ijuin T, Itoh T, Takenawa T, Mikoshiba K. IRBIT Interacts with the Catalytic Core of Phosphatidylinositol Phosphate Kinase Type Iα and IIα through Conserved Catalytic Aspartate Residues. PLoS One 2015; 10:e0141569. [PMID: 26509711 PMCID: PMC4624786 DOI: 10.1371/journal.pone.0141569] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/10/2015] [Indexed: 11/18/2022] Open
Abstract
Phosphatidylinositol phosphate kinases (PIPKs) are lipid kinases that generate phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a critical lipid signaling molecule that regulates diverse cellular functions, including the activities of membrane channels and transporters. IRBIT (IP3R-binding protein released with inositol 1,4,5-trisphosphate) is a multifunctional protein that regulates diverse target proteins. Here, we report that IRBIT forms signaling complexes with members of the PIPK family. IRBIT bound to all PIPK isoforms in heterologous expression systems and specifically interacted with PIPK type Iα (PIPKIα) and type IIα (PIPKIIα) in mouse cerebellum. Site-directed mutagenesis revealed that two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are involved in the interaction with IRBIT. Furthermore, phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfered with the interaction, suggesting that IRBIT interacts with catalytic cores of PIPKs. Mutations of phosphorylation sites in the serine-rich region of IRBIT affected the selectivity of its interaction with PIPKIα and PIPKIIα. The structural flexibility of the serine-rich region, located in the intrinsically disordered protein region, is assumed to underlie the mechanism of this interaction. Furthermore, in vitro binding experiments and immunocytochemistry suggest that IRBIT and PIPKIα interact with the Na+/HCO3− cotransporter NBCe1-B. These results suggest that IRBIT forms signaling complexes with PIPKIα and NBCe1-B, whose activity is regulated by PI(4,5)P2.
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Affiliation(s)
- Hideaki Ando
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
- * E-mail: (HA); (KM)
| | - Matsumi Hirose
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Laura Gainche
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Katsuhiro Kawaai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Benjamin Bonneau
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Toshiki Itoh
- Biosignal Research Center, Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan
| | - Tadaomi Takenawa
- Biosignal Research Center, Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
- * E-mail: (HA); (KM)
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23
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Yoo SH, Huh YH, Huh SK, Chu SY, Kim KD, Hur YS. Localization and projected role of phosphatidylinositol 4-kinases IIα and IIβ in inositol 1,4,5-trisphosphate-sensitive nucleoplasmic Ca²⁺ store vesicles. Nucleus 2015; 5:341-51. [PMID: 25482123 PMCID: PMC4152348 DOI: 10.4161/nucl.29776] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Phosphatidylinositol (PI) kinases are key molecules that participate in the phosphoinositide signaling in the cytoplasm. Despite the accumulating evidence that supports the existence and operation of independent PI signaling system in the nucleus, the exact location of the PI kinases inside the nucleus is not well defined. Here we show that PI4-kinases IIα and IIβ, which play central roles in PI(4,5)P2 synthesis and PI signaling, are localized in numerous small nucleoplasmic vesicles that function as inositol 1,4,5-trisphosphate (Ins(1,4,5)P3)-sensitive Ca(2+) stores. This is in accord with the past results that showed the localization of PI4(P)5-kinases that are essential in PI(4,5)P2 production and PI(4,5)P2 in nuclear matrix. Along with PI(4,5)P2 that also exists on the nucleoplasmic vesicle membranes, the localization of PI4-kinases IIα and IIβ in the nucleoplasmic vesicles strongly implicates the vesicles to the PI signaling as well as the Ins(1,4,5)P3-depenent Ca(2+) signaling in the nucleus. Accordingly, the nucleoplasmic vesicles indeed release Ca(2+) rapidly in response to Ins(1,4,5)P3. Further, the Ins(1,4,5)P3-induced Ca(2+) release studies suggest that PI4KIIα and IIβ are localized near the Ins(1,4,5)P3 receptor (Ins(1,4,5)P3R)/Ca(2+) channels on the Ca(2+) store vesicle membranes. In view of the widespread presence of the Ins(1,4,5)P3-dependent Ca(2+) store vesicles and the need to fine-control the nuclear Ca(2+) concentrations at multiple sites along the chromatin fibers in the nucleus, the existence of the key PI enzymes in the Ins(1,4,5)P3-dependent nucleoplasmic Ca(2+) store vesicles appears to be in perfect harmony with the physiological roles of the PI kinases in the nucleus.
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Affiliation(s)
- Seung Hyun Yoo
- a Department of Biochemistry; Inha University School of Medicine; Incheon, Korea
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24
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Silva AM, Brown JM, Buckle VJ, Wade-Martins R, Lufino MMP. Expanded GAA repeats impair FXN gene expression and reposition the FXN locus to the nuclear lamina in single cells. Hum Mol Genet 2015; 24:3457-71. [PMID: 25814655 PMCID: PMC4498154 DOI: 10.1093/hmg/ddv096] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/12/2015] [Indexed: 02/07/2023] Open
Abstract
Abnormally expanded DNA repeats are associated with several neurodegenerative diseases. In Friedreich's ataxia (FRDA), expanded GAA repeats in intron 1 of the frataxin gene (FXN) reduce FXN mRNA levels in averaged cell samples through a poorly understood mechanism. By visualizing FXN expression and nuclear localization in single cells, we show that GAA-expanded repeats decrease the number of FXN mRNA molecules, slow transcription, and increase FXN localization at the nuclear lamina (NL). Restoring histone acetylation reverses NL positioning. Expanded GAA-FXN loci in FRDA patient cells show increased NL localization with increased silencing of alleles and reduced transcription from alleles positioned peripherally. We also demonstrate inefficiencies in transcription initiation and elongation from the expanded GAA-FXN locus at single-cell resolution. We suggest that repressive epigenetic modifications at the expanded GAA-FXN locus may lead to NL relocation, where further repression may occur.
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Affiliation(s)
- Ana M Silva
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal and
| | - Jill M Brown
- Medical Research Council, Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Veronica J Buckle
- Medical Research Council, Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Richard Wade-Martins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK,
| | - Michele M P Lufino
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK,
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25
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Choi S, Thapa N, Tan X, Hedman AC, Anderson RA. PIP kinases define PI4,5P₂signaling specificity by association with effectors. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1851:711-23. [PMID: 25617736 PMCID: PMC4380618 DOI: 10.1016/j.bbalip.2015.01.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/14/2015] [Accepted: 01/16/2015] [Indexed: 12/21/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI4,5P₂) is an essential lipid messenger with roles in all eukaryotes and most aspects of human physiology. By controlling the targeting and activity of its effectors, PI4,5P₂modulates processes, such as cell migration, vesicular trafficking, cellular morphogenesis, signaling and gene expression. In cells, PI4,5P₂has a much higher concentration than other phosphoinositide species and its total content is largely unchanged in response to extracellular stimuli. The discovery of a vast array of PI4,5P₂ binding proteins is consistent with data showing that the majority of cellular PI4,5P₂is sequestered. This supports a mechanism where PI4,5P₂functions as a localized and highly specific messenger. Further support of this mechanism comes from the de novo synthesis of PI4,5P₂which is often linked with PIP kinase interaction with PI4,5P₂effectors and is a mechanism to define specificity of PI4,5P₂signaling. The association of PI4,5P₂-generating enzymes with PI4,5P₂effectors regulate effector function both temporally and spatially in cells. In this review, the PI4,5P₂effectors whose functions are tightly regulated by associations with PI4,5P₂-generating enzymes will be discussed. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Suyong Choi
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Narendra Thapa
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Xiaojun Tan
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Andrew C Hedman
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Richard A Anderson
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA; Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA.
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26
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Waugh MG. PIPs in neurological diseases. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1066-82. [PMID: 25680866 DOI: 10.1016/j.bbalip.2015.02.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/29/2015] [Accepted: 02/01/2015] [Indexed: 12/19/2022]
Abstract
Phosphoinositide (PIP) lipids regulate many aspects of cell function in the nervous system including receptor signalling, secretion, endocytosis, migration and survival. Levels of PIPs such as PI4P, PI(4,5)P2 and PI(3,4,5)P3 are normally tightly regulated by phosphoinositide kinases and phosphatases. Deregulation of these biochemical pathways leads to lipid imbalances, usually on intracellular endosomal membranes, and these changes have been linked to a number of major neurological diseases including Alzheimer's, Parkinson's, epilepsy, stroke, cancer and a range of rarer inherited disorders including brain overgrowth syndromes, Charcot-Marie-Tooth neuropathies and neurodevelopmental conditions such as Lowe's syndrome. This article analyses recent progress in this area and explains how PIP lipids are involved, to varying degrees, in almost every class of neurological disease. This article is part of a Special Issue entitled Brain Lipids.
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Affiliation(s)
- Mark G Waugh
- Lipid and Membrane Biology Group, Institute for Liver and Digestive Health, UCL, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom.
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27
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Wright BD, Simpson C, Stashko M, Kireev D, Hull-Ryde EA, Zylka MJ, Janzen WP. Development of a High-Throughput Screening Assay to Identify Inhibitors of the Lipid Kinase PIP5K1C. ACTA ACUST UNITED AC 2014; 20:655-62. [PMID: 25534829 DOI: 10.1177/1087057114564057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 11/23/2014] [Indexed: 11/16/2022]
Abstract
Phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks) regulate a variety of cellular processes, including signaling through G protein-coupled receptors (GPCRs), endocytosis, exocytosis, and cell migration. These lipid kinases synthesize phosphatidylinositol 4,5-bisphosphate (PIP2) from phosphatidylinositol 4-phosphate [PI(4)P]. Because small-molecule inhibitors of these lipid kinases did not exist, molecular and genetic approaches were predominantly used to study PIP5K1 regulation of these cellular processes. Moreover, standard radioisotope-based lipid kinase assays cannot be easily adapted for high-throughput screening. Here, we report a novel, high-throughput, microfluidic mobility shift assay to identify inhibitors of PIP5K1C. This assay uses fluorescently labeled phosphatidylinositol 4-phosphate as the substrate and recombinant human PIP5K1C. Our assay exhibited high reproducibility, had a calculated adenosine triphosphate Michaelis constant (Km) of 15 µM, performed with z' values >0.7, and was used to screen a kinase-focused library of ~4700 compounds. From this screen, we identified several potent inhibitors of PIP5K1C, including UNC3230, a compound that we recently found can reduce nociceptive sensitization in animal models of chronic pain. This novel assay will allow continued drug discovery efforts for PIP5K1C and can be adapted easily to screen additional lipid kinases.
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Affiliation(s)
- Brittany D Wright
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA National Center for Advancing Translational Science, Rockville, MD 20850
| | - Catherine Simpson
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael Stashko
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Dmitri Kireev
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Emily A Hull-Ryde
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mark J Zylka
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Department of Cell Biology and Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - William P Janzen
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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28
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Fayngerts SA, Wu J, Oxley CL, Liu X, Vourekas A, Cathopoulis T, Wang Z, Cui J, Liu S, Sun H, Lemmon MA, Zhang L, Shi Y, Chen YH. TIPE3 is the transfer protein of lipid second messengers that promote cancer. Cancer Cell 2014; 26:465-78. [PMID: 25242044 PMCID: PMC4198483 DOI: 10.1016/j.ccr.2014.07.025] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 04/29/2014] [Accepted: 07/28/2014] [Indexed: 02/04/2023]
Abstract
More than half of human cancers have aberrantly upregulated phosphoinositide signals; yet how phospholipid signals are controlled during tumorigenesis is not fully understood. We report here that TIPE3 (TNFAIP8L3) is the transfer protein of phosphoinositide second messengers that promote cancer. High-resolution crystal structure of TIPE3 shows a large hydrophobic cavity that is occupied by a phospholipid-like molecule. TIPE3 preferentially captures and shuttles two lipid second messengers, i.e., phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate, and increases their levels in the plasma membrane. Notably, human cancers have markedly upregulated TIPE3 expression. Knocking out TIPE3 diminishes tumorigenesis, whereas enforced TIPE3 expression enhances it in vivo. Thus, the function and metabolism of phosphoinositide second messengers are controlled by a specific transfer protein during tumorigenesis.
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Affiliation(s)
- Svetlana A Fayngerts
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jianping Wu
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Camilla L Oxley
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Xianglan Liu
- Institute of Immunology, School of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Anastassios Vourekas
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Terry Cathopoulis
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Zhaojun Wang
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jian Cui
- Institute of Immunology, School of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Suxia Liu
- Institute of Immunology, School of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Honghong Sun
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mark A Lemmon
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lining Zhang
- Institute of Immunology, School of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Yigong Shi
- School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Youhai H Chen
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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29
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Abstract
Genetic and pathological studies link α-synuclein to the etiology of Parkinson's disease (PD), but the normal function of this presynaptic protein remains unknown. α-Synuclein, an acidic lipid binding protein, shares high sequence identity with β- and γ-synuclein. Previous studies have implicated synucleins in synaptic vesicle (SV) trafficking, although the precise site of synuclein action continues to be unclear. Here we show, using optical imaging, electron microscopy, and slice electrophysiology, that synucleins are required for the fast kinetics of SV endocytosis. Slowed endocytosis observed in synuclein null cultures can be rescued by individually expressing mouse α-, β-, or γ-synuclein, indicating they are functionally redundant. Through comparisons to dynamin knock-out synapses and biochemical experiments, we suggest that synucleins act at early steps of SV endocytosis. Our results categorize α-synuclein with other familial PD genes known to regulate SV endocytosis, implicating this pathway in PD.
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30
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Sakagami H, Katsumata O, Hara Y, Tamaki H, Fukaya M. Preferential localization of type I phosphatidylinositol 4-phosphate 5-kinase γ at the periactive zone of mouse photoreceptor ribbon synapses. Brain Res 2014; 1586:23-33. [PMID: 25152467 DOI: 10.1016/j.brainres.2014.08.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/12/2014] [Accepted: 08/16/2014] [Indexed: 01/22/2023]
Abstract
Type I phosphatidylinositol 4-phosphate 5 kinase γ (PIP5KIγ) constitutes a major pathway for the generation of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) that regulates a variety of neuronal functions at both presynaptic and postsynaptic compartments. In this study, we examined the expression and localization of PIP5KIγ in the adult mouse retina. RT-PCR analysis revealed that PIP5KIγ_v2 was predominantly expressed in the retina while PIP5KIγ_v3 was also expressed faintly. Immunostaining of the adult mouse retina revealed intense PIP5KIγ-immunoreactivity in the inner and outer plexiform layers in a punctate manner. In the photoreceptor ribbon synapse, PIP5KIγ was highly concentrated at the periactive zone. These findings suggest that PIP5KIγ, especially PIP5KIγ_i2, is localized at the periactive zone, a functionally suitable compartment for the endocytosis of synaptic vesicles in photoreceptor ribbon synapses.
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Affiliation(s)
- Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa 252-0374, Japan.
| | - Osamu Katsumata
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa 252-0374, Japan
| | - Yoshinobu Hara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa 252-0374, Japan
| | - Hideaki Tamaki
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa 252-0374, Japan
| | - Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa 252-0374, Japan
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31
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Wright BD, Loo L, Street SE, Ma A, Taylor-Blake B, Stashko MA, Jin J, Janzen WP, Frye SV, Zylka MJ. The lipid kinase PIP5K1C regulates pain signaling and sensitization. Neuron 2014; 82:836-47. [PMID: 24853942 DOI: 10.1016/j.neuron.2014.04.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2014] [Indexed: 02/07/2023]
Abstract
Numerous pain-producing (pronociceptive) receptors signal via phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis. However, it is currently unknown which lipid kinases generate PIP2 in nociceptive dorsal root ganglia (DRG) neurons and if these kinases regulate pronociceptive receptor signaling. Here, we found that phosphatidylinositol 4-phosphate 5 kinase type 1C (PIP5K1C) is expressed at higher levels than any other PIP5K and, based on experiments with Pip5k1c(+/-) mice, generates at least half of all PIP2 in DRG neurons. Additionally, Pip5k1c haploinsufficiency reduces pronociceptive receptor signaling and TRPV1 sensitization in DRG neurons as well as thermal and mechanical hypersensitivity in mouse models of chronic pain. We identified a small molecule inhibitor of PIP5K1C (UNC3230) in a high-throughput screen. UNC3230 lowered PIP2 levels in DRG neurons and attenuated hypersensitivity when administered intrathecally or into the hindpaw. Our studies reveal that PIP5K1C regulates PIP2-dependent nociceptive signaling and suggest that PIP5K1C is a therapeutic target for chronic pain.
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Affiliation(s)
- Brittany D Wright
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lipin Loo
- Department of Cell Biology and Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sarah E Street
- Department of Cell Biology and Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Anqi Ma
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Bonnie Taylor-Blake
- Department of Cell Biology and Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Michael A Stashko
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jian Jin
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - William P Janzen
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Stephen V Frye
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mark J Zylka
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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32
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Enrichment of phosphatidylinositols with specific acyl chains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1501-8. [DOI: 10.1016/j.bbamem.2013.10.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 09/25/2013] [Accepted: 10/03/2013] [Indexed: 12/21/2022]
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Kang MS, Baek SH, Chun YS, Moore AZ, Landman N, Berman D, Yang HO, Morishima-Kawashima M, Osawa S, Funamoto S, Ihara Y, Di Paolo G, Park JH, Chung S, Kim TW. Modulation of lipid kinase PI4KIIα activity and lipid raft association of presenilin 1 underlies γ-secretase inhibition by ginsenoside (20S)-Rg3. J Biol Chem 2013; 288:20868-20882. [PMID: 23723072 PMCID: PMC3774358 DOI: 10.1074/jbc.m112.445734] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 05/20/2013] [Indexed: 01/09/2023] Open
Abstract
Amyloid β-peptide (Aβ) pathology is an invariant feature of Alzheimer disease, preceding any detectable clinical symptoms by more than a decade. To this end, we seek to identify agents that can reduce Aβ levels in the brain via novel mechanisms. We found that (20S)-Rg3, a triterpene natural compound known as ginsenoside, reduced Aβ levels in cultured primary neurons and in the brains of a mouse model of Alzheimer disease. The (20S)-Rg3 treatment induced a decrease in the association of presenilin 1 (PS1) fragments with lipid rafts where catalytic components of the γ-secretase complex are enriched. The Aβ-lowering activity of (20S)-Rg3 directly correlated with increased activity of phosphatidylinositol 4-kinase IIα (PI4KIIα), a lipid kinase that mediates the rate-limiting step in phosphatidylinositol 4,5-bisphosphate synthesis. PI4KIIα overexpression recapitulated the effects of (20S)-Rg3, whereas reduced expression of PI4KIIα abolished the Aβ-reducing activity of (20S)-Rg3 in neurons. Our results substantiate an important role for PI4KIIα and phosphoinositide modulation in γ-secretase activity and Aβ biogenesis.
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Affiliation(s)
- Min Suk Kang
- From the Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032
| | | | - Yoon Sun Chun
- Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
| | - A Zenobia Moore
- From the Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032
| | - Natalie Landman
- From the Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032
| | - Diego Berman
- From the Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032
| | - Hyun Ok Yang
- Natural Products Research Center, Korea Institute of Science and Technology-Gangneung Institute, Gangneung, Gangwon-do 210-340, Korea
| | - Maho Morishima-Kawashima
- Department of Molecular Neuropathology, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0808, Japan
| | - Satoko Osawa
- Department of Neuropathology, Faculty of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Satoru Funamoto
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan, and
| | - Yasuo Ihara
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan, and
| | - Gilbert Di Paolo
- From the Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032
| | - Jeong Hill Park
- Research Institute of Pharmaceutical Sciences, Seoul National University, College of Pharmacy, Seoul 151-742, Korea
| | - Sungkwon Chung
- Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea,.
| | - Tae-Wan Kim
- From the Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032,.
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Bayot A, Reichman S, Lebon S, Csaba Z, Aubry L, Sterkers G, Husson I, Rak M, Rustin P. Cis-silencing of PIP5K1B evidenced in Friedreich's ataxia patient cells results in cytoskeleton anomalies. Hum Mol Genet 2013; 22:2894-904. [PMID: 23552101 DOI: 10.1093/hmg/ddt144] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease characterized by ataxia, variously associating heart disease, diabetes mellitus and/or glucose intolerance. It results from intronic expansion of GAA triplet repeats at the FXN locus. Homozygous expansions cause silencing of the FXN gene and subsequent decreased expression of the encoded mitochondrial frataxin. Detailed analyses in fibroblasts and neuronal tissues from FRDA patients have revealed profound cytoskeleton anomalies. So far, however, the molecular mechanism underlying these cytoskeleton defects remains unknown. We show here that gene silencing spreads in cis over the PIP5K1B gene in cells from FRDA patients (circulating lymphocytes and primary fibroblasts), correlating with expanded GAA repeat size. PIP5K1B encodes phosphatidylinositol 4-phosphate 5-kinase β type I (pip5k1β), an enzyme functionally linked to actin cytoskeleton dynamics that phosphorylates phosphatidylinositol 4-phosphate [PI(4)P] to generate phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. Accordingly, loss of pip5k1β function in FRDA cells was accompanied by decreased PI(4,5)P2 levels and was shown instrumental for destabilization of the actin network and delayed cell spreading. Knockdown of PIP5K1B in control fibroblasts using shRNA reproduced abnormal actin cytoskeleton remodeling, whereas over-expression of PIP5K1B, but not FXN, suppressed this phenotype in FRDA cells. In addition to provide new insights into the consequences of the FXN gene expansion, these findings raise the question whether PIP5K1B silencing may contribute to the variable manifestation of this complex disease.
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Affiliation(s)
- Aurélien Bayot
- Hôpital Robert Debré, INSERM UMR 676 Faculté de Médecine Denis Diderot, Université Paris 7, 75019 Paris, France.
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35
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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36
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Sun Y, Thapa N, Hedman AC, Anderson RA. Phosphatidylinositol 4,5-bisphosphate: targeted production and signaling. Bioessays 2013; 35:513-22. [PMID: 23575577 DOI: 10.1002/bies.201200171] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI4,5P(2)) is a key lipid signaling molecule that regulates a vast array of biological activities. PI4,5P(2) can act directly as a messenger or can be utilized as a precursor to generate other messengers: inositol trisphosphate, diacylglycerol, or phosphatidylinositol 3,4,5-trisphosphate. PI4,5P(2) interacts with hundreds of different effector proteins. The enormous diversity of PI4,5P(2) effector proteins and the spatio-temporal control of PI4,5P(2) generation allow PI4,5P(2) signaling to control a broad spectrum of cellular functions. PI4,5P(2) is synthesized by phosphatidylinositol phosphate kinases (PIPKs). The array of PIPKs in cells enables their targeting to specific subcellular compartments through interactions with targeting factors that are often PI4,5P(2) effectors. These interactions are a mechanism to define spatial and temporal PI4,5P(2) synthesis and the specificity of PI4,5P(2) signaling. In turn, the regulation of PI4,5P(2) effectors at specific cellular compartments has implications for understanding how PI4,5P(2) controls cellular processes and its role in diseases.
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Affiliation(s)
- Yue Sun
- University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
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37
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Elouarrat D, van der Velden YU, Jones DR, Moolenaar WH, Divecha N, Haramis APG. Role of phosphatidylinositol 5-phosphate 4-kinase α in zebrafish development. Int J Biochem Cell Biol 2013; 45:1293-301. [PMID: 23542014 DOI: 10.1016/j.biocel.2013.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 03/12/2013] [Accepted: 03/13/2013] [Indexed: 10/27/2022]
Abstract
Phosphatidylinositol 5-phosphate 4-kinases (PIP4Ks) phosphorylate phosphatidylinositol 5-phosphate (PI5P) to generate phosphatidylinositol 4,5-bisphosphate; their most likely function is the regulation of the levels of PI5P, a putative signalling intermediate. There are three mammalian PIP4Ks isoforms (α, β and γ), but their physiological roles remain poorly understood. In the present study, we identified the zebrafish orthologue (zPIP4Kα) of the high-activity human PIP4K α isoform and analyzed its role in embryonic development. RT-PCR analysis and whole-mount in situ hybridization experiments showed that zPIP4Kα is maternally expressed. At later embryonic stages, high PIP4Kα expression was detected in the head and the pectoral fins. Knockdown of zPIP4Kα by antisense morpholino oligonucleotides led to severe morphological abnormalities, including midbody winding defects at 48hpf. The abnormal phenotype could be rescued, at least in large part, by injection of human PIP4Kα mRNA. Our results reveal a key role for PIP4Kα and its activity in vertebrate tissue homeostasis and organ development.
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Affiliation(s)
- Dalila Elouarrat
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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38
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Szalinski CM, Guerriero CJ, Ruiz WG, Docter BE, Rbaibi Y, Pastor-Soler NM, Apodaca G, Puthenveedu MA, Weisz OA. PIP5KIβ selectively modulates apical endocytosis in polarized renal epithelial cells. PLoS One 2013; 8:e53790. [PMID: 23342003 PMCID: PMC3547069 DOI: 10.1371/journal.pone.0053790] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/05/2012] [Indexed: 12/21/2022] Open
Abstract
Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis.
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Affiliation(s)
- Christina M. Szalinski
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Christopher J. Guerriero
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Wily G. Ruiz
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Brianne E. Docter
- Grand Valley State University, Allendale, Michigan, United States of America
| | - Youssef Rbaibi
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Núria M. Pastor-Soler
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Gerard Apodaca
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Manojkumar A. Puthenveedu
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Ora A. Weisz
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Neely GG, Rao S, Costigan M, Mair N, Racz I, Milinkeviciute G, Meixner A, Nayanala S, Griffin RS, Belfer I, Dai F, Smith S, Diatchenko L, Marengo S, Haubner BJ, Novatchkova M, Gibson D, Maixner W, Pospisilik JA, Hirsch E, Whishaw IQ, Zimmer A, Gupta V, Sasaki J, Kanaho Y, Sasaki T, Kress M, Woolf CJ, Penninger JM. Construction of a global pain systems network highlights phospholipid signaling as a regulator of heat nociception. PLoS Genet 2012; 8:e1003071. [PMID: 23236288 PMCID: PMC3516557 DOI: 10.1371/journal.pgen.1003071] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Accepted: 09/21/2012] [Indexed: 01/06/2023] Open
Abstract
The ability to perceive noxious stimuli is critical for an animal's survival in the face of environmental danger, and thus pain perception is likely to be under stringent evolutionary pressure. Using a neuronal-specific RNAi knock-down strategy in adult Drosophila, we recently completed a genome-wide functional annotation of heat nociception that allowed us to identify α2δ3 as a novel pain gene. Here we report construction of an evolutionary-conserved, system-level, global molecular pain network map. Our systems map is markedly enriched for multiple genes associated with human pain and predicts a plethora of novel candidate pain pathways. One central node of this pain network is phospholipid signaling, which has been implicated before in pain processing. To further investigate the role of phospholipid signaling in mammalian heat pain perception, we analysed the phenotype of PIP5Kα and PI3Kγ mutant mice. Intriguingly, both of these mice exhibit pronounced hypersensitivity to noxious heat and capsaicin-induced pain, which directly mapped through PI3Kγ kinase-dead knock-in mice to PI3Kγ lipid kinase activity. Using single primary sensory neuron recording, PI3Kγ function was mechanistically linked to a negative regulation of TRPV1 channel transduction. Our data provide a systems map for heat nociception and reinforces the extraordinary conservation of molecular mechanisms of nociception across different species. Nociception is the perception of noxious, potentially damaging stimuli; and this pain or its equivalent behavioral readout is evolutionarily conserved from fruit flies to humans. Using genetic techniques in the fruit fly, we have been able to evaluate the potential functional contribution of every gene in the fruit fly genome for a role in avoidance of high noxious temperatures (heat pain-like responses). Using this functional genomics data set, we have developed a conserved network map of heat pain/nociception that predicts numerous conserved genes and pathways as novel pain pathways, including phospholipid signaling. Studies in multiple mutant mice confirmed a role for lipid signaling in pain perception, and more specifically we identify the critical lipid kinase (PI3Kγ) as a negative regulator of TRPV1 (receptor for noxious heat and capsaicin, the active component in chili peppers) signaling. This finding shows that our fly-based genetic pain network map is a valuable tool for the discovery of novel “nociception genes” in mammals.
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Affiliation(s)
- G Gregory Neely
- Neuroscience Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.
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40
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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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Legate KR, Montag D, Böttcher RT, Takahashi S, Fässler R. Comparative phenotypic analysis of the two major splice isoforms of phosphatidylinositol phosphate kinase type Iγ in vivo. J Cell Sci 2012; 125:5636-46. [PMID: 22976293 DOI: 10.1242/jcs.102145] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Localized production of polyphosphoinositides is critical for their signaling function. To examine the biological relevance of specific pools of phosphatidylinositol 4,5-bisphosphate we compared the consequences of genetically ablating all isoforms of phosphatidylinositol phosphate (PIP) kinase type Iγ (PIPKIγ), encoded by the gene Pip5k1c, versus ablation of a specific splice isoform, PIPKIγ_i2, with respect to three reported PIPKIγ functions. Ablation of PIPKIγ_i2 caused a neuron-specific endocytosis defect similar to that found in PIPKIγ(-/-) mice, while agonist-induced calcium signaling was reduced in PIPKIγ(-/-) cells, but was not affected in the absence of PIPKIγ_i2. A reported contribution of PIPKIγ to epithelial integrity was not evident in PIPKIγ(-/-) mice. Given that mice lacking PIPKIγ_i2 live a normal lifespan whereas PIPKIγ(-/-) mice die shortly after birth, we propose that PIPKIγ-mediated metabotropic calcium signaling may represent an essential function of PIPKIγ, whereas functions specific to the PIPKIγ_i2 splice isoform are not essential for survival.
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Affiliation(s)
- Kyle R Legate
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, 82152 Germany
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42
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Clathrin and phosphatidylinositol-4,5-bisphosphate regulate autophagic lysosome reformation. Nat Cell Biol 2012; 14:924-34. [PMID: 22885770 DOI: 10.1038/ncb2557] [Citation(s) in RCA: 219] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/09/2012] [Indexed: 12/23/2022]
Abstract
Autophagy is a lysosome-based degradation pathway. During autophagy, lysosomes fuse with autophagosomes to form autolysosomes. Following starvation-induced autophagy, nascent lysosomes are formed from autolysosomal membranes through an evolutionarily conserved cellular process, autophagic lysosome reformation (ALR), which is critical for maintaining lysosome homeostasis. Here we report that clathrin and phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P(2)) regulate ALR. Combining a screen of candidates identified through proteomic analysis of purified ALR tubules, and large-scale RNAi knockdown, we unveiled a tightly regulated molecular pathway that controls lysosome homeostasis, in which clathrin and PtdIns(4,5)P(2) are the central components. Our functional study demonstrates the central role of clathrin and its associated proteins in cargo sorting, phospholipid conversion, initiation of autolysosome tubulation, and proto-lysosome budding during ALR. Our data not only uncover a molecular pathway by which lysosome homeostasis is maintained through the ALR process, but also reveal unexpected functions of clathrin and PtdIns(4,5)P(2) in lysosome homeostasis.
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Koch M, Holt M. Coupling exo- and endocytosis: an essential role for PIP₂ at the synapse. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1114-32. [PMID: 22387937 DOI: 10.1016/j.bbalip.2012.02.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Revised: 02/12/2012] [Accepted: 02/13/2012] [Indexed: 12/24/2022]
Abstract
Chemical synapses are specialist points of contact between two neurons, where information transfer takes place. Communication occurs through the release of neurotransmitter substances from small synaptic vesicles in the presynaptic terminal, which fuse with the presynaptic plasma membrane in response to neuronal stimulation. However, as neurons in the central nervous system typically only possess ~200 vesicles, high levels of release would quickly lead to a depletion in the number of vesicles, as well as leading to an increase in the area of the presynaptic plasma membrane (and possible misalignment with postsynaptic structures). Hence, synaptic vesicle fusion is tightly coupled to a local recycling of synaptic vesicles. For a long time, however, the exact molecular mechanisms coupling fusion and subsequent recycling remained unclear. Recent work now indicates a unique role for the plasma membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP(2)), acting together with the vesicular protein synaptotagmin, in coupling these two processes. In this work, we review the evidence for such a mechanism and discuss both the possible advantages and disadvantages for vesicle recycling (and hence signal transduction) in the nervous system. This article is part of a Special Issue entitled Lipids and Vesicular Transport.
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Affiliation(s)
- Marta Koch
- Laboratory of Neurogenetics, VIB Center for the Biology of Disease and K.U. Leuven Center for Human Genetics, O&N4 Herestraat 49, 3000 Leuven, Belgium
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Essential role for phosphatidylinositol 4,5-bisphosphate in the expression, regulation, and gating of the slow afterhyperpolarization current in the cerebral cortex. J Neurosci 2012; 31:18303-12. [PMID: 22171034 DOI: 10.1523/jneurosci.3203-11.2011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Many neurons of the CNS and peripheral nervous system express a slow afterhyperpolarization that is mediated by a slow calcium-activated potassium current. Previous work has shown that this aftercurrent regulates repetitive firing and is an important target for neuromodulators signaling through receptors coupled to G-proteins of the Gα(q-11) and Gα(s) subtypes. Yet, despite considerable effort, a molecular-level understanding of the potassium current underlying the slow afterhyperpolarization and its modulation has proven elusive. Here, we use a combination of pharmacological and molecular biological approaches in cortical brain slices to show that the functional expression of the slow calcium-activated afterhyperpolarizing current in pyramidal cells is critically dependent on membrane phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] and that this dependence accounts for its inhibition by 5-HT(2A) receptors. Furthermore, we show that PtdIns(4,5)P(2) regulates the calcium sensitivity of I(sAHP) in a manner that suggests it acts downstream from the rise in intracellular calcium. These results clarify key functional aspects of the slow afterhyperpolarization current and its modulation by 5-HT(2A) receptors and point to a key role for PtdIns(4,5)P(2) in the gating of this current.
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45
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Zhang L, Mao YS, Janmey PA, Yin HL. Phosphatidylinositol 4, 5 bisphosphate and the actin cytoskeleton. Subcell Biochem 2012; 59:177-215. [PMID: 22374091 DOI: 10.1007/978-94-007-3015-1_6] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Dynamic changes in PM PIP(2) have been implicated in the regulation of many processes that are dependent on actin polymerization and remodeling. PIP(2) is synthesized primarily by the type I phosphatidylinositol 4 phosphate 5 kinases (PIP5Ks), and there are three major isoforms, called a, b and g. There is emerging evidence that these PIP5Ks have unique as well as overlapping functions. This review will focus on the isoform-specific roles of individual PIP5K as they relate to the regulation of the actin cytoskeleton. We will review recent advances that establish PIP(2) as a critical regulator of actin polymerization and cytoskeleton/membrane linkages, and show how binding of cytoskeletal proteins to membrane PIP(2) might alter lateral or transverse movement of lipids to affect raft formation or lipid asymmetry. The mechanisms for specifying localized increase in PIP(2) to regulate dynamic actin remodeling will also be discussed.
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Affiliation(s)
- Li Zhang
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, 75390-9040, Dallas, TX, USA
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46
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Abstract
Synaptic transmission is amongst the most sophisticated and tightly controlled biological phenomena in higher eukaryotes. In the past few decades, tremendous progress has been made in our understanding of the molecular mechanisms underlying multiple facets of neurotransmission, both pre- and postsynaptically. Brought under the spotlight by pioneer studies in the areas of secretion and signal transduction, phosphoinositides and their metabolizing enzymes have been increasingly recognized as key protagonists in fundamental aspects of neurotransmission. Not surprisingly, dysregulation of phosphoinositide metabolism has also been implicated in synaptic malfunction associated with a variety of brain disorders. In the present chapter, we summarize current knowledge on the role of phosphoinositides at the neuronal synapse and highlight some of the outstanding questions in this research field.
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Affiliation(s)
- Samuel G Frere
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, 630 West 168th Street, P&S 12-420C, 10032, New York, USA
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47
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Shulga YV, Topham MK, Epand RM. Study of arachidonoyl specificity in two enzymes of the PI cycle. J Mol Biol 2011; 409:101-12. [PMID: 21477596 DOI: 10.1016/j.jmb.2011.03.071] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/27/2011] [Accepted: 03/30/2011] [Indexed: 01/19/2023]
Abstract
We identified a conserved pattern of residues L-X((3-4))-R-X((2))-L-X((4))-G, in which -X((n))- is n residues of any amino acid, in two enzymes acting on the polyunsaturated fatty acids, diacylglycerol kinase epsilon (DGKɛ) and phosphatidylinositol-4-phosphate-5-kinase Iα (PIP5K Iα). DGKɛ is the only one of the 10 mammalian isoforms of DGK that exhibits arachidonoyl specificity and is the only isoform with the motif mentioned above. Mutations of the essential residues in this motif result in the loss of arachidonoyl specificity. Furthermore, DGKα can be converted to an enzyme having this motif by substituting only one residue. When DGKα was mutated so that it gained the motif, the enzyme also gained some specificity for arachidonoyl-containing diacylglycerol. This motif is present also in an isoform of phosphatidylinositol-4-phosphate-5-kinase that we demonstrated had arachidonoyl specificity for its substrate. Single residue mutations within the identified motif of this isoform result in the loss of activity against an arachidonoyl substrate. The importance of acyl chain specificity for the phosphatidic acid activation of phosphatidylinositol-4-phosphate-5-kinase is also shown. We demonstrate that the acyl chain dependence of this phosphatidic acid activation is dependent on the substrate. This is the first demonstration of a motif that endows specificity for an acyl chain in enzymes DGKε and PIP5K Iα.
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Affiliation(s)
- Yulia V Shulga
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada
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48
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Nakatsu F, Perera RM, Lucast L, Zoncu R, Domin J, Gertler FB, Toomre D, De Camilli P. The inositol 5-phosphatase SHIP2 regulates endocytic clathrin-coated pit dynamics. ACTA ACUST UNITED AC 2010; 190:307-15. [PMID: 20679431 PMCID: PMC2922640 DOI: 10.1083/jcb.201005018] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
SHIP2 is recruited early to clathrin-coated pits by the scaffold protein intersectin and dissociates before fission. Phosphatidylinositol (PI) 4,5-bisphosphate (PI(4,5)P2) and its phosphorylated product PI 3,4,5-triphosphate (PI(3,4,5)P3) are two major phosphoinositides concentrated at the plasma membrane. Their levels, which are tightly controlled by kinases, phospholipases, and phosphatases, regulate a variety of cellular functions, including clathrin-mediated endocytosis and receptor signaling. In this study, we show that the inositol 5-phosphatase SHIP2, a negative regulator of PI(3,4,5)P3-dependent signaling, also negatively regulates PI(4,5)P2 levels and is concentrated at endocytic clathrin-coated pits (CCPs) via interactions with the scaffold protein intersectin. SHIP2 is recruited early at the pits and dissociates before fission. Both knockdown of SHIP2 expression and acute production of PI(3,4,5)P3 shorten CCP lifetime by enhancing the rate of pit maturation, which is consistent with a positive role of both SHIP2 substrates, PI(4,5)P2 and PI(3,4,5)P3, on coat assembly. Because SHIP2 is a negative regulator of insulin signaling, our findings suggest the importance of the phosphoinositide metabolism at CCPs in the regulation of insulin signal output.
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Affiliation(s)
- Fubito Nakatsu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
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