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Dollins DE, Xiong JP, Endo-Streeter S, Anderson DE, Bansal VS, Ponder JW, Ren Y, York JD. A structural basis for lithium and substrate binding of an inositide phosphatase. J Biol Chem 2021; 296:100059. [PMID: 33172890 PMCID: PMC7948987 DOI: 10.1074/jbc.ra120.014057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 10/29/2020] [Accepted: 11/10/2020] [Indexed: 01/07/2023] Open
Abstract
Inositol polyphosphate 1-phosphatase (INPP1) is a prototype member of metal-dependent/lithium-inhibited phosphomonoesterase protein family defined by a conserved three-dimensional core structure. Enzymes within this family function in distinct pathways including inositide signaling, gluconeogenesis, and sulfur assimilation. Using structural and biochemical studies, we report the effect of substrate and lithium on a network of metal binding sites within the catalytic center of INPP1. We find that lithium preferentially occupies a key site involved in metal-activation only when substrate or product is added. Mutation of a conserved residue that selectively coordinates the putative lithium-binding site results in a dramatic 100-fold reduction in the inhibitory constant as compared with wild-type. Furthermore, we report the INPP1/inositol 1,4-bisphosphate complex which illuminates key features of the enzyme active site. Our results provide insights into a structural basis for uncompetitive lithium inhibition and substrate recognition and define a sequence motif for metal binding within this family of regulatory phosphatases.
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Affiliation(s)
- D Eric Dollins
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Jian-Ping Xiong
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Stuart Endo-Streeter
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - David E Anderson
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Vinay S Bansal
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Jay W Ponder
- Department of Chemistry, Washington University, St Louis, Missouri, USA
| | - Yi Ren
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - John D York
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA.
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Kitanaka N, Hall FS, Uhl GR, Kitanaka J. Lithium Pharmacology and a Potential Role of Lithium on Methamphetamine Abuse and Dependence. Curr Drug Res Rev 2020; 11:85-91. [PMID: 31875781 DOI: 10.2174/2589977511666190620141824] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/18/2019] [Accepted: 05/10/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND The effectiveness of lithium salts in neuropsychiatric disorders such as bipolar disorder, Alzheimer's disease, and treatment-resistant depression has been documented in an extensive scientific literature. Lithium inhibits inositol monophosphatase, inositol polyphosphate 1- phosphatase, and glycogen synthase kinase-3 and decreases expression level of tryptophan hydroxylase 2, conceivably underlying the mood stabilizing effects of lithium, as well as procognitive and neuroprotective effects. However, the exact molecular mechanisms of action of lithium on mood stabilizing and pro-cognitive effects in humans are still largely unknown. OBJECTIVE On the basis of the known aspects of lithium pharmacology, this review will discuss the possible mechanisms underlying the therapeutic effects of lithium on positive symptoms of methamphetamine abuse and dependence. CONCLUSION It is possible that lithium treatment reduces the amount of newly synthesized phosphatidylinositol, potentially preventing or reversing neuroadaptations contributing to behavioral sensitization induced by methamphetamine. In addition, it is suggested that exposure to repeated doses of methamphetamine induces hyperactivation of glycogen synthase kinase-3β in the nucleus accumbens and in dorsal hippocampus, resulting in a long-term alterations in synaptic plasticity underlying behavioral sensitization as well as other behavioral deficits in memory-related behavior. Therefore it is clear that glycogen synthase kinase-3β inhibitors can be considered as a potential candidate for the treatment of methamphetamine abuse and dependence.
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Affiliation(s)
- Nobue Kitanaka
- Department of Pharmacology, Hyogo College of Medicine, Hyogo 663-8501, Japan
| | - Frank Scott Hall
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, Ohio 43614, United States
| | - George Richard Uhl
- Neurology and Research Services, New Mexico VA Healthcare System, Albuquerque, New Mexico 87108, United States.,Departments of Neurology, Neuroscience, Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Junichi Kitanaka
- Department of Pharmacology, Hyogo College of Medicine, Hyogo 663-8501, Japan
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Murry R, Kniemeyer O, Krause K, Saiardi A, Kothe E. Crosstalk between Ras and inositol phosphate signaling revealed by lithium action on inositol monophosphatase in Schizophyllum commune. Adv Biol Regul 2019; 72:78-88. [PMID: 30639095 PMCID: PMC6520614 DOI: 10.1016/j.jbior.2019.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 12/31/2018] [Accepted: 01/02/2019] [Indexed: 06/09/2023]
Abstract
Mushroom forming basidiomycete Schizophyllum commune has been used as a tractable model organism to study fungal sexual development. Ras signaling activation via G-protein-coupled receptors (GPCRs) has been postulated to play a significant role in the mating and development of S. commune. In this study, a crosstalk between Ras signaling and inositol phosphate signaling by inositol monophosphatase (IMPase) is revealed. Constitutively active Ras1 leads to the repression of IMPase transcription and lithium action on IMPase activity is compensated by the induction of IMPase at transcriptome level. Astonishingly, in S. commune lithium induces a considerable shift to inositol phosphate metabolism leading to a massive increase in the level of higher phosphorylated inositol species up to the inositol pyrophosphates. The lithium induced metabolic changes are not observable in a constitutively active Ras1 mutant. In addition to that, proteome profile helps us to elucidate an overview of lithium action to the broad aspect of fungal metabolism and cellular signaling. Taken together, these findings imply a crosstalk between Ras and inositol phosphate signaling.
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Affiliation(s)
- Reyna Murry
- Friedrich Schiller University Jena, Institute of Microbiology, Jena, Germany
| | - Olaf Kniemeyer
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute Jena, Germany
| | - Katrin Krause
- Friedrich Schiller University Jena, Institute of Microbiology, Jena, Germany
| | - Adolfo Saiardi
- Medical Research Council (MRC) Laboratory for Molecular Cell Biology, Department of Biochemistry and Molecular Biology, University College London, London, UK.
| | - Erika Kothe
- Friedrich Schiller University Jena, Institute of Microbiology, Jena, Germany.
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4
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Meisel JD, Kim DH. Inhibition of Lithium-Sensitive Phosphatase BPNT-1 Causes Selective Neuronal Dysfunction in C. elegans. Curr Biol 2016; 26:1922-8. [PMID: 27397889 DOI: 10.1016/j.cub.2016.05.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/09/2016] [Accepted: 05/19/2016] [Indexed: 11/26/2022]
Abstract
Lithium has been a mainstay for the treatment of bipolar disorder, yet the molecular mechanisms underlying its action remain enigmatic. Bisphosphate 3'-nucleotidase (BPNT-1) is a lithium-sensitive phosphatase that catalyzes the breakdown of cytosolic 3'-phosphoadenosine 5'-phosphate (PAP), a byproduct of sulfation reactions utilizing the universal sulfate group donor 3'-phosphoadenosine 5'-phosphosulfate (PAPS) [1-3]. Loss of BPNT-1 leads to the toxic accumulation of PAP in yeast and non-neuronal cell types in mice [4, 5]. Intriguingly, BPNT-1 is expressed throughout the mammalian brain [4], and it has been hypothesized that inhibition of BPNT-1 could contribute to the effects of lithium on behavior [5]. Here, we show that loss of BPNT-1 in Caenorhabditis elegans results in the selective dysfunction of two neurons, the bilaterally symmetric pair of ASJ chemosensory neurons. As a result, BPNT-1 mutants are defective in behaviors dependent on the ASJ neurons, such as dauer exit and pathogen avoidance. Acute treatment with lithium also causes dysfunction of the ASJ neurons, and we show that this effect is reversible and mediated specifically through inhibition of BPNT-1. Finally, we show that the selective effect of lithium on the nervous system is due in part to the limited expression of the cytosolic sulfotransferase SSU-1 in the ASJ neuron pair. Our data suggest that lithium, through inhibition of BPNT-1 in the nervous system, can cause selective toxicity to specific neurons, resulting in corresponding effects on behavior of C. elegans.
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Affiliation(s)
- Joshua D Meisel
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Dennis H Kim
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
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5
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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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6
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Roles for nucleotide phosphatases in sulfate assimilation and skeletal disease. Adv Biol Regul 2013; 52:229-38. [PMID: 22100882 DOI: 10.1016/j.advenzreg.2011.11.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 11/04/2011] [Indexed: 12/26/2022]
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Affiliation(s)
- Philip W Majerus
- Division of Hematology, Washington University Medical School, St Louis, Missouri 63110, USA.
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8
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Caldwell KK, Sosa M, Buckley CT. Identification of mitogen-activated protein kinase docking sites in enzymes that metabolize phosphatidylinositols and inositol phosphates. Cell Commun Signal 2006; 4:2. [PMID: 16445858 PMCID: PMC1379644 DOI: 10.1186/1478-811x-4-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Accepted: 01/30/2006] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Reversible interactions between the components of cellular signaling pathways allow for the formation and dissociation of multimolecular complexes with spatial and temporal resolution and, thus, are an important means of integrating multiple signals into a coordinated cellular response. Several mechanisms that underlie these interactions have been identified, including the recognition of specific docking sites, termed a D-domain and FXFP motif, on proteins that bind mitogen-activated protein kinases (MAPKs). We recently found that phosphatidylinositol-specific phospholipase C-gamma1 (PLC-gamma1) directly binds to extracellular signal-regulated kinase 2 (ERK2), a MAPK, via a D-domain-dependent mechanism. In addition, we identified D-domain sequences in several other PLC isozymes. In the present studies we sought to determine whether MAPK docking sequences could be recognized in other enzymes that metabolize phosphatidylinositols (PIs), as well as in enzymes that metabolize inositol phosphates (IPs). RESULTS We found that several, but not all, of these enzymes contain identifiable D-domain sequences. Further, we found a high degree of conservation of these sequences and their location in human and mouse proteins; notable exceptions were PI 3-kinase C2-gamma, PI 4-kinase type IIbeta, and inositol polyphosphate 1-phosphatase. CONCLUSION The results indicate that there may be extensive crosstalk between MAPK signaling and signaling pathways that are regulated by cellular levels of PIs or IPs.
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Affiliation(s)
- Kevin K Caldwell
- Department of Neurosciences University of New Mexico Health Sciences Center Albuquerque, NM 87131 USA
| | - Marcos Sosa
- Department of Neurosciences University of New Mexico Health Sciences Center Albuquerque, NM 87131 USA
| | - Colin T Buckley
- Department of Neurosciences University of New Mexico Health Sciences Center Albuquerque, NM 87131 USA
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9
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McDonagh MB, Ferguson KL, Bacic A, Gardner GE, Hegarty RS. Variation in protein abundance profiles in the M. semitendinosus of lambs bred from sires selected on the basis of growth and muscling potential. ACTA ACUST UNITED AC 2006. [DOI: 10.1071/ar04277] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Relative abundance of proteins localised in the nuclear-enriched, total cell membrane and cytosolic fractions of the semitendinosus muscle was compared between lambs bred from control (C), high muscling (M), and high growth rate (G) sires. In total, 31 proteins were identified whose abundance was differentially regulated between sire type. Differences in hind-limb muscle development between M lambs and C and G lambs were reflected in levels of proteins that regulate or function in cellular mechanisms of protein and energy metabolism. Despite no apparent difference in hind-limb muscle growth in G lambs compared to C, G lambs exhibited marked differences in proteins involved in regulation and function of energy metabolism. These results detail pathways that can be specifically targeted to enhance muscle accretion and growth in lambs. The development of means to manipulate these cellular mechanisms may yield greater gains in muscle accretion and growth rate than breeding on the basis for genetic capacity alone.
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Affiliation(s)
- Javad Torabinejad
- Department of Biochemistry, Virginia Tech, 306 Fralin Biotechnology Center, Blacksburg, VA 24061, USA
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11
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Seeds AM, Bastidas RJ, York JD. Molecular Definition of a Novel Inositol Polyphosphate Metabolic Pathway Initiated by Inositol 1,4,5-Trisphosphate 3-Kinase Activity in Saccharomyces cerevisiae. J Biol Chem 2005; 280:27654-61. [PMID: 15944147 DOI: 10.1074/jbc.m505089200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The production of inositol polyphosphate (IPs) and pyrophosphates (PP-IPs) from inositol 1,4,5-trisphosphate (I(1,4,5)P3) requires the 6-/3-/5-kinase activity of Ipk2 (also known as Arg82 and inositol polyphosphate multikinase). Here, we probed the distinct roles for I(1,4,5)P3 6- versus 3-kinase activities in IP metabolism and cellular functions reported for Ipk2. Expression of either I(1,4,5)P3 6- or 3-kinase activity rescued growth of ipk2-deficient yeast at high temperatures, whereas only 6-kinase activity enabled growth on ornithine as the sole nitrogen source. Analysis of IP metabolism revealed that the 3-kinase initiated the synthesis of novel pathway consisting of over eleven IPs and PP-IPs. This pathway was present in wild-type and ipk2 null cells, albeit at low levels as compared with inositol hexakisphosphate synthesis. The primary route of synthesis was: I(1,4,5)P3 --> I(1,3,4,5)P4 --> I(1,2,3,4,5)P5 --> PP-IP4 --> PP2-IP3 and required Kcs1 (or possibly Ipk2), Ipk1, a novel inositol pyrophosphate synthase, and then Kcs1 again, respectively. Mutation of kcs1 ablated this pathway in ipk2 null cells and overexpression of Kcs1 in ipk2 mutant cells phenocopied IP3K expression, confirming it harbors a novel 3-kinase activity. Our work provides a revised genetic map of IP metabolism in yeast and evidence for dosage compensation between IPs and PP-IPs downstream of I(1,4,5)P3 in the regulation of nucleocytoplasmic processes.
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Affiliation(s)
- Andrew M Seeds
- Department of Pharmacology and Cancer Biology, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA
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12
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Patel S, Yenush L, Rodríguez PL, Serrano R, Blundell TL. Crystal structure of an enzyme displaying both inositol-polyphosphate-1-phosphatase and 3'-phosphoadenosine-5'-phosphate phosphatase activities: a novel target of lithium therapy. J Mol Biol 2002; 315:677-85. [PMID: 11812139 DOI: 10.1006/jmbi.2001.5271] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lithium cations exert profound and selective psychopharmacological effects on ameliorate manic-depressive psychosis. Although lithium is an effective drug for both treatment and prophylaxis of bipolar disorder, the precise mechanism of action is not well understood. Lithium acts as both an uncompetitive and non-competitive inhibitor of several lithium- sensitive phosphatases with regard to substrate and magnesium cofactor, respectively. In this work, we report the crystal structure and reaction mechanism of Rattus norvegicus 3'-phosphoadenosine 5'-phosphate and inositol 1,4-bisphosphate phosphatase (RnPIP), a recently identified target of lithium therapy. This Li(+)-sensitive enzyme plays a crucial role in several cellular processes, such as RNA processing, sulphation reactions and probably inositol recycling. RnPIP specifically removes the 3'-phosphate group of 3'-phosphoadenosine 5'-phosphate (PAP) and the 1'-phosphate group of inositol 1,4-bisphosphate (I(1),(4)P(2)) producing AMP and inositol 4'-phosphate, respectively. The crystal structure of RnPIP complexed with AMP, Pi and magnesium ions at 1.69 A resolution provides insight into the reaction mechanism of the hydrolysis of PAP. The core fold of the enzyme is equivalent to that found in other Li(+)-sensitive phosphatases, such as inositol monophosphatase, but molecular modelling of I(1),(4)P(2) in the RnPIP active site reveals important structural determinants that accommodate this additional substrate. RnPIP is potently inhibited by lithium and, as the accumulation of PAP inhibits a variety of proteins, including sulphotransferases and RNA processing enzymes, this dual specificity enzyme represents a potential target of lithium action, in addition to inositol monophosphatases.
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Affiliation(s)
- S Patel
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
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13
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Takenawa T, Itoh T. Phosphoinositides, key molecules for regulation of actin cytoskeletal organization and membrane traffic from the plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1533:190-206. [PMID: 11731330 DOI: 10.1016/s1388-1981(01)00165-2] [Citation(s) in RCA: 227] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Phosphoinositide plays a critical role not only in generating second messengers, such as inositol 1,4,5-trisphosphate and diacylglycerol, but also in modulating a variety of cellular functions including cytoskeletal organization and membrane trafficking. Many inositol lipid kinases and phosphatases appear to regulate the concentration of a variety of phosphoinositides in a specific area, thereby inducing spatial and temporal changes in their availability. For example, local concentration changes in phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) in response to extracellular stimuli cause the reorganization of actin filaments and a change in cell shape. PI(4,5)P(2) uncaps the barbed end of actin filaments and increases actin nucleation by modulating a variety of actin regulatory proteins, leading to de novo actin polymerization. PI(4,5)P(2) also plays a key role in membrane trafficking processes. In endocytosis, PI(4,5)P(2) targets clathrin-associated proteins to endocytic vesicles, leading to clathrin-coated pit formation. On the contrary, PI(4,5)P(2) must be dephosphorylated when they shed clathrin coats to fuse endosome. Thus, through regulating actin cytoskeleton organization and membrane trafficking, phosphoinositides play crucial roles in a variety of cell functions such as growth, polarity, movement, and pattern formation.
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Affiliation(s)
- T Takenawa
- Department of Biology, Institute of Medical Science, University of Tokyo, Japan.
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14
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York JD, Guo S, Odom AR, Spiegelberg BD, Stolz LE. An expanded view of inositol signaling. ADVANCES IN ENZYME REGULATION 2001; 41:57-71. [PMID: 11384737 DOI: 10.1016/s0065-2571(00)00025-x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- J D York
- Howard Hughes Medical Institute, Departments of Pharmacology and Cancer Biology, and of Biochemistry, Duke University Medical Center, DUMC 3813, Durham NC 27710, USA.
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15
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Majerus PW, Kisseleva MV, Norris FA. The role of phosphatases in inositol signaling reactions. J Biol Chem 1999; 274:10669-72. [PMID: 10196133 DOI: 10.1074/jbc.274.16.10669] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- P W Majerus
- Department of Internal Medicine, Division of Hematology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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16
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York JD, Xiong JP, Spiegelberg B. Nuclear inositol signaling: a structural and functional approach. ADVANCES IN ENZYME REGULATION 1998; 38:365-74. [PMID: 9762363 DOI: 10.1016/s0065-2571(97)00018-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J D York
- Department of Pharmacology, Duke University Medical Center, Durham, NC 27710, USA.
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17
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Acharya JK, Labarca P, Delgado R, Jalink K, Zuker CS. Synaptic defects and compensatory regulation of inositol metabolism in inositol polyphosphate 1-phosphatase mutants. Neuron 1998; 20:1219-29. [PMID: 9655509 DOI: 10.1016/s0896-6273(00)80502-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Phosphoinositides function as important second messengers in a wide range of cellular processes. Inositol polyphosphate 1-phosphatase (IPP) is an enzyme essential for the hydrolysis of the 1-phosphate from either Ins(1,4)P2 or Ins(1,3,4)P3. This enzyme is Li+ sensitive, and is one of the proposed targets of Li+ therapy in manic-depressive illness. Drosophila ipp mutants accumulate IP2 in their system and are incapable of metabolizing exogenous Ins(1,4)P2. Notably, ipp mutants demonstrate compensatory upregulation of an alternative branch in the inositol-phosphate metabolism tree, thus providing a means of ensuring continued availability of inositol. We demonstrate that ipp mutants have a defect in synaptic transmission resulting from a dramatic increase in the probability of vesicle release at larval neuromuscular junctions. We also show that Li+ phenocopies this effect in wild-type synapses. Together, these results support a role for phosphoinositides in synaptic vesicle function in vivo and mechanistically question the "lithium hypothesis."
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Affiliation(s)
- J K Acharya
- Howard Hughes Medical Institute, and Department of Biology, University of California, San Diego, La Jolla 92093, USA
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18
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Murguía JR, Bellés JM, Serrano R. The yeast HAL2 nucleotidase is an in vivo target of salt toxicity. J Biol Chem 1996; 271:29029-33. [PMID: 8910555 DOI: 10.1074/jbc.271.46.29029] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The yeast halotolerance gene HAL2 encodes a nucleotidase that dephosphorylates 3'-phosphoadenosine 5'-phosphate (PAP) and 3'-phosphoadenosine 5'-phosphosulfate (PAPS), intermediates of the sulfate assimilation pathway. This nucleotidase is inhibited by Na+ and Li+ but not by K+. Incubation of wild-type yeast cells with NaCl and LiCl, but not with KCl, increased intracellular PAP to millimolar concentrations. No depletion of the pool of adenine nucleotides (AMP, ADP, ATP) was observed. Other stresses such as heat shock or oxidative stress did not result in PAP accumulation. PAPS concentrations also increased during salt stress but remained lower than 0.5 microM. S-Adenosylmethionine concentrations decreased by 50%, reflecting inhibition of sulfate assimilation during salt stress. Salt-induced PAP accumulation was attenuated in a yeast strain overexpressing HAL2. This strain grew better than the wild type under salt stress. These results suggest that the cation sensitivity of the HAL2 nucleotidase is an important determinant of the inhibition of yeast growth by sodium and lithium salts. In addition to blocking sulfate assimilation by product inhibition of PAPS reductase, PAP accumulation may have other unidentified toxic effects.
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Affiliation(s)
- J R Murguía
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia, Spain.
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19
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Wilson MP, Majerus PW. Isolation of inositol 1,3,4-trisphosphate 5/6-kinase, cDNA cloning and expression of the recombinant enzyme. J Biol Chem 1996; 271:11904-10. [PMID: 8662638 DOI: 10.1074/jbc.271.20.11904] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Inositol 1,3,4-trisphosphate 5/6-kinase was purified 12,900-fold from calf brain using chromatography on heparin-agarose and affinity elution with inositol hexakisphosphate. The final preparation contained proteins of 48 and 36-38 kDa. All of these proteins had the same amino-terminal sequence and were enzymatically active. The smaller species represent proteolysis products with carboxyl-terminal truncation. The Km of the enzyme for inositol 1,3,4-trisphosphate was 80 nM with a Vmax of 60 nmol of product/min/mg of protein. The amino acid sequence of the tryptic peptide HSKLLARPAGGLVGERTCNAXP matched the protein sequence encoded by a human expressed sequence tag clone (GB T09063) at 16 of 22 residues. The expressed sequence tag clone was used to screen a human fetal brain cDNA library to obtain a cDNA clone of 1991 base pairs (bp) that predicts a protein of 46 kDa. The clone encodes the amino-terminal amino acid sequence obtained from the purified calf brain preparation, suggesting that it represents its human homologue. The cDNA was expressed as a fusion protein in Escherichia coli and was found to have inositol 1,3,4-trisphosphate 5/6-kinase activity. Remarkably, both the purified calf brain and recombinant proteins produced both inositol 1,3,4,6-tetrakisphosphate and inositol 1,3,4,5-tetrakisphosphate as products in a ratio of 2.3-5:1. This finding proves that a single kinase phosphorylates inositol in both the D5 and D6 positions. Northern blot analysis identified a transcript of 3.6 kilobases in all tissues with the highest levels in brain. The composite cDNA isolated contains 3054 bp with a poly(A) tail, suggesting that 500-600 bp of 5' sequence remains to be identified.
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Affiliation(s)
- M P Wilson
- Division of Hematology-Oncology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Quintero FJ, Garciadeblás B, Rodríguez-Navarro A. The SAL1 gene of Arabidopsis, encoding an enzyme with 3'(2'),5'-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase activities, increases salt tolerance in yeast. THE PLANT CELL 1996. [PMID: 8721754 DOI: 10.2307/3870330] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A cDNA library in a yeast expression vector was prepared from roots of Arabidopsis exposed to salt and was used to select Li(+)-tolerant yeast transformants. The cDNA SAL1 isolated from one of these transformants encodes a polypeptide of 353 amino acid residues. This protein is homologous to the HAL2 and CysQ phosphatases of yeast and Escherichia coli, respectively. Partial cDNA sequences in the data bases indicate that rice produces a phosphatase highly homologous to SAL1 and that a second gene homologous to SAL1 exists in Arabidopsis. The SAL1 protein expressed in E. coli showed 3'(2'),5'-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase activities. In yeast, SAL1 restored the ability of a hal2/met22 mutant to grow on sulfate as a sole sulfur source, increased the intracellular Li+ tolerance, and modified Na+ and Li+ effluxes. We propose that the product of SAL1 participates in the sulfur assimilation pathway as well as in the phosphoinositide signaling pathway and that changes in the latter may affect Na+ and Li+ fluxes.
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Affiliation(s)
- F J Quintero
- Departamento de Biotecnología, Universidad Politécnica de Madrid, Spain
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21
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Quintero FJ, Garciadeblás B, Rodríguez-Navarro A. The SAL1 gene of Arabidopsis, encoding an enzyme with 3'(2'),5'-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase activities, increases salt tolerance in yeast. THE PLANT CELL 1996; 8:529-37. [PMID: 8721754 PMCID: PMC161118 DOI: 10.1105/tpc.8.3.529] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
A cDNA library in a yeast expression vector was prepared from roots of Arabidopsis exposed to salt and was used to select Li(+)-tolerant yeast transformants. The cDNA SAL1 isolated from one of these transformants encodes a polypeptide of 353 amino acid residues. This protein is homologous to the HAL2 and CysQ phosphatases of yeast and Escherichia coli, respectively. Partial cDNA sequences in the data bases indicate that rice produces a phosphatase highly homologous to SAL1 and that a second gene homologous to SAL1 exists in Arabidopsis. The SAL1 protein expressed in E. coli showed 3'(2'),5'-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase activities. In yeast, SAL1 restored the ability of a hal2/met22 mutant to grow on sulfate as a sole sulfur source, increased the intracellular Li+ tolerance, and modified Na+ and Li+ effluxes. We propose that the product of SAL1 participates in the sulfur assimilation pathway as well as in the phosphoinositide signaling pathway and that changes in the latter may affect Na+ and Li+ fluxes.
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Affiliation(s)
- F J Quintero
- Departamento de Biotecnología, Universidad Politécnica de Madrid, Spain
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22
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Tercero JA, Espinosa JC, Lacalle RA, Jiménez A. The biosynthetic pathway of the aminonucleoside antibiotic puromycin, as deduced from the molecular analysis of the pur cluster of Streptomyces alboniger. J Biol Chem 1996; 271:1579-90. [PMID: 8576156 DOI: 10.1074/jbc.271.3.1579] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The pur cluster which encodes the puromycin biosynthetic pathway from Streptomyces alboniger was subcloned as a 13-kilobase fragment in plasmid pIJ702 and expressed in an apparently regulated manner in the heterologous host Streptomyces lividans. The sequencing of a 9.1-kilobase DNA fragment completed the sequence of pur. This permitted identification of seven new open reading frames in the order: napH, pur7, pur10, pur6, pur4, pur5, and pur3. The latter is followed by the known pac, dmpM, and pur8 genes. Nine open reading frames are transcribed rightward as a unit in opposite direction to that of the pur8 gene which is expressed as a monocistronic transcript from the right-most end. napH encodes the known N-acetylpuromycin N-acetylhydrolase. The deduced products from other open reading frames present similarities to: NTP pyrophosphohydrolases (pur7), several oxidoreductases (pur10), the putative LmbC protein of the lincomycin biosynthetic pathway from Streptomyces lincolnensis (pur6), S-adenosylmethionine-dependent methyltransferases (pur5), a variety of presumed aminotransferases (pur4), and several monophosphatases (pur3). According to these similarities and to previous biochemical work, a puromycin biosynthetic pathway has been deduced. No cluster-associated regulatory gene was found. However, both pur10 and pur6 genes contain a TTA codon, which suggests that they are translationally controlled by the bldA gene product, a specific tRNA(Leu).
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Affiliation(s)
- J A Tercero
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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23
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Affiliation(s)
- V Raboy
- USDA-ARS Range Weeds and Cereals Research Unit, Montana State University, Bozeman 59717, USA
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Gillaspy GE, Keddie JS, Oda K, Gruissem W. Plant inositol monophosphatase is a lithium-sensitive enzyme encoded by a multigene family. THE PLANT CELL 1995; 7:2175-85. [PMID: 8718627 PMCID: PMC161071 DOI: 10.1105/tpc.7.12.2175] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
myo-Inositol monophosphatase (IMP) is a soluble, Li(+)-sensitive protein that catalyzes the removal of a phosphate from myo-inositol phosphate substrates. IMP is required for de novo inositol synthesis from glucose 6-phosphate and for breakdown of inositol trisphosphate, a second messenger generated by the phosphatidylinositol signaling pathway. We cloned the IMP gene from tomato (LeIMP) and show that the plant enzyme is encoded by a small gene family. Three different LeIMP cDNAs encode distinct but highly conserved IMP enzymes that are catalytically active in vitro. Similar to the single IMP from animals, the activities of all three LeIMPs are inhibited by low concentrations of LiCl. LeIMP mRNA levels are developmentally regulated in seedlings and fruit and in response to light. Immunoblot analysis detected three proteins of distinct molecular masses (30, 29, and 28 kD) in tomato; these correspond to the predicted molecular masses of the LeIMPs encoded by the genes. Immunoreactive proteins in the same size range are also present in several other plants. Immunolocalization studies indicated that many cell types within seedlings accumulate LeIMP proteins. In particular, cells associated with the vasculature express high levels of LeIMP protein; this may indicate a coordinate regulation between phloem transport and synthesis of inositol. The presence of three distinct enzymes in tomato most likely reflects the complexity of inositol utilization in higher plants.
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Affiliation(s)
- G E Gillaspy
- Department of Plant Biology, University of California-Berkeley 94720-3102, USA
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25
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Welshons WV, Engler KS, Taylor JA, Grady LH, Curran EM. Lithium-stimulated proliferation and alteration of phosphoinositide metabolites in MCF-7 human breast cancer cells. J Cell Physiol 1995; 165:134-44. [PMID: 7559794 DOI: 10.1002/jcp.1041650116] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Lithium, which is used to treat bipolar psychiatric disorders, can stimulate proliferation of a number of cells in tissue culture. Proliferation of MCF-7 human breast cancer cells, which also respond to EGF and estrogens, was stimulated by LiCl (1-5 mM) within the concentration range that is encountered during human therapy with lithium. Stimulation of growth was specific for lithium; rubidium, potassium, and sodium showed no such effect. In the presence of antiestrogen, lithium stimulated the growth of hormone-dependent breast cancer cells MCF-7, ZR-75-1, and T47D but not hormone-independent MDA-MB-231 cells or an estrogen-independent clone of MCF-7 cells. Lithium-stimulated proliferation was limited by cytotoxicity which could be moderated by added potassium chloride (5-20 mM) in the medium. Each of the mitogens lithium, 17 beta-estradiol, and EGF increased the rate of uptake of myo-inositol into MCF-7 cells. Whether normalized to inositol lipids, to protein, or to DNA, steady-state levels of inositol phosphates were elevated by each of the mitogens including lithium, which inhibits the breakdown of inositol phosphates in the phosphoinositide signaling pathway. These data indicate that therapeutic concentrations of lithium can stimulate the proliferation of human breast cancer cells by a mechanism that may involve the phosphoinositide pathway.
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Affiliation(s)
- W V Welshons
- Department of Veterinary Biomedical Sciences, University of Missouri-Columbia 65211, USA
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26
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Norris FA, Auethavekiat V, Majerus PW. The isolation and characterization of cDNA encoding human and rat brain inositol polyphosphate 4-phosphatase. J Biol Chem 1995; 270:16128-33. [PMID: 7608176 DOI: 10.1074/jbc.270.27.16128] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Inositol polyphosphate 4-phosphatase, an enzyme of the inositol phosphate signaling pathway, catalyzes the hydrolysis of the 4-position phosphate of inositol 3,4-bisphosphate, inositol 1,3,4-trisphosphate, and phosphatidylinositol 3,4-bisphosphate. The amino acid sequences of tryptic and CNBr peptides of the enzyme isolated from rat brain were determined. Degenerate oligonucleotide primers based on this sequence were used to amplify a 74-base pair polymerase chain reaction product. This product was used to isolate a 5607-base pair composite cDNA, which had an open reading frame encoding a protein with 939 amino acids with a predicted molecular mass of 105,588 Da. The rat brain polymerase chain reaction product was used as a probe to isolate a human brain cDNA that predicts a protein with 938 amino acids and a molecular mass of 105,710 Da. Remarkably, the human and rat proteins were 97% identical. Recombinant rat protein expressed in Escherichia coli catalyzed the hydrolysis of all three substrates of the 4-phosphatase. Northern blot hybridization indicates that the 4-phosphatase is widely expressed in rat tissues with the highest levels of expression occurring in brain, heart, and skeletal muscle. Polyclonal antiserum directed against the carboxyl terminus of the 4-phosphatase immunoprecipitated > 95% of the 4-phosphatase activity in crude homogenates of rat brain, heart, skeletal muscle, and spleen, suggesting that this enzyme accounts for the 4-phosphate activity present in rat tissues. This antiserum also immunoprecipitated the 4-phosphatase from human platelet sonicates.
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Affiliation(s)
- F A Norris
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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27
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Taylor JA, Grady LH, Engler KS, Welshons WV. Relationship of growth stimulated by lithium, estradiol, and EGF to phospholipase C activity in MCF-7 human breast cancer cells. Breast Cancer Res Treat 1995; 34:265-77. [PMID: 7579491 DOI: 10.1007/bf00689718] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Lithium-stimulated MCF-7 cell proliferation was compared to proliferation stimulated by other mitogens for this cell line-estradiol (E2) and epidermal growth factor (EGF)-and lithium was found to be effective within a narrow concentration range. Mitogenic effects of lithium on proliferation stimulated by E2 and EGF were additive below maximum, but were not synergistic. The phosphoinositide pathway is a cell signaling system involved in cell proliferation, within which phospholipase C (PLC)-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] leads to the production of the second messengers inositol-1,4,5-trisphosphate [Ins(1,4,5)P3] and diacylglycerol (DAG), as well as to calcium mobilization. At mitogen concentrations which maximally stimulated cell growth, estradiol stimulated both growth and PLC activity, while EGF and lithium stimulated cell growth but had little effect on the activity of the enzyme. Dose-responses with EGF revealed that a low concentration (0.1 ng/ml, 0.017 nM) of EGF appeared to stimulate both PLC activity and cell growth, but that higher concentrations of EGF which stimulated greater proliferation inhibited PLC activity. Steady-state levels of inositol phosphates including inositol trisphosphate were increased by all three mitogens. In growth assays, the phorbol ester phorbol 12-myristate-13-acetate (PMA), which mimics the actions of DAG, stimulated some cell growth, but dioctanoylglycerol, an additional DAG analog, and the calcium ionophore A23187, alone or with the DAG analogs, had no effect. These results suggest that PLC-mediated PtdIns(4,5)P2 hydrolysis is not primarily associated with signaling proliferation by lithium or EGF in MCF-7 breast cancer cells.
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Affiliation(s)
- J A Taylor
- Department of Veterinary Biomedical Sciences, University of Missouri-Columbia 65211, USA
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28
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York JD, Ponder JW, Majerus PW. Definition of a metal-dependent/Li(+)-inhibited phosphomonoesterase protein family based upon a conserved three-dimensional core structure. Proc Natl Acad Sci U S A 1995; 92:5149-53. [PMID: 7761465 PMCID: PMC41866 DOI: 10.1073/pnas.92.11.5149] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Inositol polyphosphate 1-phosphatase, inositol monophosphate phosphatase, and fructose 1,6-bisphosphatase share a sequence motif, Asp-Pro-(Ile or Leu)-Asp-(Gly or Ser)-(Thr or Ser), that has been shown by crystallographic and mutagenesis studies to bind metal ions and participate in catalysis. We compared the six alpha-carbon coordinates of this motif from the crystal structures of these three phosphatases and found that they are superimposable with rms deviations ranging from 0.27 to 0.60 A. Remarkably, when these proteins were aligned by this motif a common core structure emerged, defined by five alpha-helices and 11 beta-strands comprising 155 residues having rms deviations ranging from 1.48 to 2.66 A. We used the superimposed structures to align the sequences within the common core, and a distant relationship was observed suggesting a common ancestor. The common core was used to align the sequences of several other proteins that share significant similarity to inositol monophosphate phosphatase, including proteins encoded by fungal qa-X and qutG, bacterial suhB and cysQ (identical to amtA), and yeast met22 (identical to hal2). Evolutionary comparison of the core sequences indicate that five distinct branches exist within this family. These proteins share metal-dependent/Li(+)-sensitive phosphomonoesterase activity, and each predicted tree branch exhibits unique substrate specificity. Thus, these proteins define an ancient structurally conserved family involved in diverse metabolic pathways including inositol signaling, gluconeogenesis, sulfate assimilation, and possibly quinone metabolism. Furthermore, we suggest that this protein family identifies candidate enzymes to account for both the therapeutic and toxic actions of Li+ as it is used in patients treated for manic depressive disease.
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Affiliation(s)
- J D York
- Division of Hematology-Oncology, Washington University School of Medicine, St. Louis, MO 63110, USA
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29
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Matsuhisa A, Suzuki N, Noda T, Shiba K. Inositol monophosphatase activity from the Escherichia coli suhB gene product. J Bacteriol 1995; 177:200-5. [PMID: 8002619 PMCID: PMC176573 DOI: 10.1128/jb.177.1.200-205.1995] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The suhB gene is located at 55 min on the Escherichia coli chromosome and encodes a protein of 268 amino acids. Mutant alleles of suhB have been isolated as extragenic suppressors for the protein secretion mutation (secY24), the heat shock response mutation (rpoH15), and the DNA synthesis mutation (dnaB121) (K. Shiba, K. Ito, and T. Yura, J. Bacteriol. 160:696-701, 1984; R. Yano, H. Nagai, K. Shiba, and T. Yura, J. Bacteriol. 172:2124-2130, 1990; S. Chang, D. Ng, L. Baird, and C. Georgopoulos, J. Biol. Chem. 266:3654-3660, 1991). These mutant alleles of suhB cause cold-sensitive cell growth, indicating that the suhB gene is essential at low temperatures. Little work has been done, however, to elucidate the role of the product of suhB in a normal cell and the suppression mechanisms of the suhB mutations in the aforementioned mutants. The sequence similarity shared between the suhB gene product and mammalian inositol monophosphatase has prompted us to test the inositol monophosphatase activity of the suhB gene product. We report here that the purified SuhB protein showed inositol monophosphatase activity. The kinetic parameters of SuhB inositol monophosphatase (Km = 0.071 mM; Vmax = 12.3 mumol/min per mg) are similar to those of mammalian inositol monophosphatase. The ssyA3 and suhB2 mutations, which were isolated as extragenic suppressors for secY24 and rpoH15, respectively, had a DNA insertion at the 5' proximal region of the suhB gene, and the amount of SuhB protein within mutant cells decreased. The possible role of suhB in E. coli is discussed.
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Affiliation(s)
- A Matsuhisa
- Research & Development Center, Fuso Pharmaceutical Industries, Osaka, Japan
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30
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York JD, Ponder JW, Chen ZW, Mathews FS, Majerus PW. Crystal structure of inositol polyphosphate 1-phosphatase at 2.3-A resolution. Biochemistry 1994; 33:13164-71. [PMID: 7947723 DOI: 10.1021/bi00249a002] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Bovine inositol polyphosphate 1-phosphatase (1-ptase), M(r) = 44,000, is a Mg(2+)-dependent/Li(+)-sensitive enzyme that catalyzes the hydrolysis of the 1-position phosphate from inositol 1,4-bisphosphate and inositol 1,3,4-trisphosphate. We have determined the crystal structure of recombinant bovine 1-ptase in the presence of Mg2+ by multiple isomorphous replacement. The structure is currently refined to an R value of 0.198 for 15,563 reflections within a resolution range of 8.0-2.3 A. 1-Ptase is monomeric in the crystal, consistent with biochemical data, and folds into an alternatively layered alpha/beta/alpha/beta sandwich. The central core of 1-ptase consists of a six-stranded antiparallel beta sheet perpendicular to two parallel three-turn alpha-helices. The beta sheet is flanked by two antiparallel six-turn alpha-helices aligned parallel to the beta sheet, and the central helices are flanked by a five-stranded largely parallel beta sheet. Two neighboring metal binding sites are located in adjacent acidic pockets formed by the intersection of several secondary structure elements including an unusual kink structure formed by the "DPIDST" sequence motif. The fold of 1-ptase is similar to that of two other metal-dependent/Li(+)-sensitive phosphatases, inositol monophosphate phosphatase and fructose 1,6-bisphosphatase despite minimal amino acid identity. Comparison of the active-site pockets of these proteins will likely provide insight into substrate binding and the mechanisms of metal-dependent catalysis and Li+ inhibition.
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Affiliation(s)
- J D York
- Division of Hematology/Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
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32
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Hydrolysis of phosphatidylinositol 3,4-bisphosphate by inositol polyphosphate 4-phosphatase isolated by affinity elution chromatography. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37027-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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33
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Pollack SJ, Knowles MR, Atack JR, Broughton HB, Ragan CI, Osborne S, McAllister G. Probing the role of metal ions in the mechanism of inositol monophosphatase by site-directed mutagenesis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 217:281-7. [PMID: 8223565 DOI: 10.1111/j.1432-1033.1993.tb18244.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Since inhibition of myo-inositol monophosphatase (EC 3.1.3.25) by lithium ions and the resulting attenuation of phosphatidylinositol cycle activity may be the mechanism by which lithium exerts its therapeutic effect in the treatment of manic depression, it is of great interest to understand the mechanism of the enzyme and how lithium and other metals interact with it. Divalent magnesium is essential for enzyme activity, whereas Li+ and high concentrations of Mg2+ act as uncompetitive inhibitors with respect to substrate. From the recently solved crystal structure of the human enzyme, several amino acid residues in the active site were targeted for mutagenesis studies. Nine single-residue substituted mutants were characterized with regard to catalytic parameters, Mg2+ dependence, and Li+ inhibition. In addition, a terbium fluorescence assay was developed to determine the metal binding properties of the wild-type and mutant enzymes. Although none of these mutations affected Km for substrate substantially, the mutations Glu70-->Gln, Glu70-->Asp, Asp90-->Asn and Thr95-->Ala, in which residues within coordinating distance of the active site metal were modified, all resulted in large reductions in catalytic activity. The position of Glu70 in the crystal structure further suggests that this residue may be involved in activating water for nucleophilic attack on the substrate. The mutations Lys36-->Ile, Asp90-->Asn, Thr95-->Ala, Thr95-->Ser, His217-->Gln, and Cys218-->Ala all resulted in parallel reductions in both lithium and magnesium affinity, suggesting that Li+ and Mg2+ share a common binding site.
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Affiliation(s)
- S J Pollack
- Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, England
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York JD, Veile RA, Donis-Keller H, Majerus PW. Cloning, heterologous expression, and chromosomal localization of human inositol polyphosphate 1-phosphatase. Proc Natl Acad Sci U S A 1993; 90:5833-7. [PMID: 8390685 PMCID: PMC46817 DOI: 10.1073/pnas.90.12.5833] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Inositol polyphosphate 1-phosphatase, an enzyme in the phosphatidylinositol signaling pathway, catalyzes the hydrolysis of the 1 position phosphate from inositol 1,3,4-trisphosphate and inositol 1,4-bisphosphate. We used a cDNA that encodes bovine inositol polyphosphate 1-phosphatase as a probe to isolate the human counterpart by low-stringency hybridization. The 1.74-kb human cDNA has 341 bp of 5' untranslated region, 180 bp of 3' untranslated region, poly(A)32, and predicts a protein of 399 amino acids. Human and bovine inositol polyphosphate 1-phosphatases show 84% amino acid sequence identity. Northern blot analysis from a variety of human tissues demonstrates that a 1.9-kb mRNA is ubiquitously expressed with highest levels in pancreas and kidney. Several higher molecular weight mRNAs also are expressed in brain, muscle, heart, and liver. We have confirmed the functional identity of the human cDNA by heterologous expression in NIH 3T3 fibroblasts, COS-7 cells and Escherichia coli. Polymerase chain reaction assay of a panel of human-rodent somatic cell hybrid DNA using human inositol polyphosphate 1-phosphatase-specific DNA primers resulted in amplification of a specific product using chromosome 2 DNA as template. Fluorescence in situ hybridization of metaphase chromosomes localizes the gene to chromosome 2 band q32. The identification of the human inositol polyphosphate 1-phosphatase gene locus provides a target for linkage analysis to identify defects in patients with inherited psychiatric disorders that respond to lithium ions, an inhibitor of the enzyme.
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Affiliation(s)
- J D York
- Division of Hematology-Oncology, Washington University School of Medicine, St. Louis, MO 63110
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35
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Atack JR, Cook SM, Watt AP, Fletcher SR, Ragan CI. In vitro and in vivo inhibition of inositol monophosphatase by the bisphosphonate L-690,330. J Neurochem 1993; 60:652-8. [PMID: 8380439 DOI: 10.1111/j.1471-4159.1993.tb03197.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have previously described the synthesis of bisphosphonate-containing inhibitors of inositol monophosphatase. In the present study, a more detailed examination of the in vitro and in vivo properties of one of these compounds, L-690,330, is described. L-690,330 is a competitive inhibitor of inositol monophosphatase with a Ki, depending on the source of IMPase, of between 0.2 and 2 microM. Although approximately 1,000-fold more potent in vitro than lithium, in muscarinic ml receptor-transfected Chinese hamster ovary cells prelabelled with [3H]inositol, L-690,330 only produced 40% of the accumulation of [3H]inositol monophosphates achieved by lithium at the same concentration (10 mM), suggesting that the ability of L-690,330 to cross the cell membrane is limited. Nevertheless, under conditions of cholinergic stimulation (100 mg/kg of pilocarpine s.c.), high doses of L-690,330 were able to increase brain inositol(l)phosphate levels in vivo to three- to fourfold control levels. This effect was dose dependent (ED50 = 0.3 mmol/kg s.c.) and was maximal after 1 h. In peripheral tissues, the effects of L-690,330 on inositol(l)phosphate levels mimicked those of lithium both qualitatively and quantitatively. However, in the brain, the effects of L-690,330 were much less than seen with lithium, consistent with the blood-brain barrier restricting access of the polar L-690,330 into the CNS, thereby further limiting entry of compound into cells in the brain. In the future, it may be possible to develop prodrugs of this compound, which circumvent many of the cell permeability problems inherent in bisphosphonate compounds.
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Affiliation(s)
- J R Atack
- Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, England, U.K
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36
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Bone R, Springer JP, Atack JR. Structure of inositol monophosphatase, the putative target of lithium therapy. Proc Natl Acad Sci U S A 1992; 89:10031-5. [PMID: 1332026 PMCID: PMC50271 DOI: 10.1073/pnas.89.21.10031] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Inositol monophosphatase (EC 3.1.3.25), the putative molecular site of action of lithium therapy for manic-depressive illness, plays a key role in the phosphatidylinositol signaling pathway by catalyzing the hydrolysis of inositol monophosphates. To provide a structural basis from which to design better therapeutic agents for manic-depressive illness, the structure of human inositol monophosphatase has been determined to 2.1-A resolution by using x-ray crystallography. The enzyme exists as a dimer of identical subunits, each folded into a five-layered sandwich of three pairs of alpha-helices and two beta-sheets. Sulfate and an inhibitory lanthanide cation (Gd3+) are bound at identical sites on each subunit and establish the positions of the active sites. Each site is located in a large hydrophilic cavern that is at the base of the two central helices where several segments of secondary structure intersect. Comparison of the phosphatase aligned sequences of several diverse genes with the phosphatase structure suggests that the products of these genes and the phosphatase form a structural family with a conserved metal binding site.
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Affiliation(s)
- R Bone
- Department of Biophysical Chemistry, Merck Research Laboratories, Rahway, NJ 07065
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37
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Ross T, Wang F, Majerus P. Mammalian cells that express Bacillus cereus phosphatidylinositol-specific phospholipase C have increased levels of inositol cyclic 1:2-phosphate, inositol 1-phosphate, and inositol 2-phosphate. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)88644-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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38
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McAllister G, Whiting P, Hammond EA, Knowles MR, Atack JR, Bailey FJ, Maigetter R, Ragan CI. cDNA cloning of human and rat brain myo-inositol monophosphatase. Expression and characterization of the human recombinant enzyme. Biochem J 1992; 284 ( Pt 3):749-54. [PMID: 1377913 PMCID: PMC1132602 DOI: 10.1042/bj2840749] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Inositol monophosphatase (EC 3.1.3.25) is a key enzyme in the phosphoinositide cell-signalling system. Its role is to provide inositol required for the resynthesis of phosphatidylinositol and polyphosphoinositides. It is the probable pharmacological target for lithium action in brain. Using probes derived from the bovine inositol monophosphatase cDNA we have isolated cDNA clones encoding the human and rat brain enzymes. The enzyme is highly conserved in all three species (79% identical). The coding region of the human cDNA was inserted into a bacterial expression vector. The expressed recombinant enzyme was purified and its biochemical properties examined. The human enzyme is very similar to the bovine enzyme.
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Affiliation(s)
- G McAllister
- Merck Sharp and Dohme Research Laboratories, Harlow, Essex, U.K
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Gu M, Warshawsky I, Majerus PW. Cloning and expression of a cytosolic megakaryocyte protein-tyrosine-phosphatase with sequence homology to retinaldehyde-binding protein and yeast SEC14p. Proc Natl Acad Sci U S A 1992; 89:2980-4. [PMID: 1557404 PMCID: PMC48787 DOI: 10.1073/pnas.89.7.2980] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Protein tyrosine phosphorylation is important in the regulation of cell growth, the cell cycle, and malignant transformation. We have cloned a cDNA that encodes a cytosolic protein-tyrosine-phosphatase (PTPase), MEG2, from MEG-01 cell and human umbilical vein endothelial cell cDNA libraries. The 4-kilobase cDNA sequence of PTPase MEG2 corresponds in length to the mRNA transcript detected by Northern blotting. The predicted open reading frame encodes a 68-kDa protein composed of 593 amino acids and has no apparent signal or transmembrane sequences, suggesting that it is a cytosolic protein. The C-terminal region has a PTPase catalytic domain that has 30-40% amino acid identity to other known PTPases. The N-terminal region has 254 amino acids that are 28% identical to cellular retinaldehyde-binding protein and 24% identical to yeast SEC14p, a protein that has phosphatidylinositol transfer activity and is required for protein secretion through the Golgi complex in yeast. Recombinant PTPase MEG2 expressed in Escherichia coli possesses PTPase activity. PTPase MEG2 mRNA was detected in 12 cell lines tested, which suggests that this phosphatase is widely expressed. The structure of PTPase MEG2 implies that a tyrosine phosphatase could participate in the transfer of hydrophobic ligands or in functions of the Golgi apparatus.
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Affiliation(s)
- M Gu
- Division of Hematology-Oncology, Washington University School of Medicine, St. Louis, MO 63110
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Abstract
Bovine inositol monophosphatase (IMP) and several homologous proteins were found to share two sequence motifs with bovine inositol polyphosphate 1-phosphatase (IPP). These motifs may correspond to binding sites within IMP and IPP for inositol phosphates or for lithium, since both substances are bound by these proteins. This suggests that the proteins homologous to IMP, which have diverse biological roles but whose function is not clear, may act by enhancing the synthesis or degradation of phosphorylated compounds.
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Affiliation(s)
- A F Neuwald
- Institute for Biomedical Computing, Washington University School of Medicine, St. Louis, MO 63110
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Ross T, Jefferson A, Mitchell C, Majerus P. Cloning and expression of human 75-kDa inositol polyphosphate-5-phosphatase. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54920-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Gu MX, York JD, Warshawsky I, Majerus PW. Identification, cloning, and expression of a cytosolic megakaryocyte protein-tyrosine-phosphatase with sequence homology to cytoskeletal protein 4.1. Proc Natl Acad Sci U S A 1991; 88:5867-71. [PMID: 1648233 PMCID: PMC51979 DOI: 10.1073/pnas.88.13.5867] [Citation(s) in RCA: 155] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have isolated a cDNA encoding a third type of protein-tyrosine-phosphatase. We screened human megakaryoblastic cell line (MEG-01) an umbilical vein endothelial cell cDNA libraries to obtain a 3.7-kilobase cDNA designated PTPase MEG. Northern blot analysis of MEG-01 RNA detected a 3.7-kilobase transcript, suggesting that a full-length cDNA has been identified. PTPase MEG cDNA contains an open reading frame of 926 amino acids. The cDNA has a G+C-rich 5' untranslated region of 771 nucleotides that has the potential to form stable stem-loop structures and has two upstream ATG codons. The predicted protein (Mr = 105,910) has no apparent membrane-spanning region and contains a single protein-tyrosine-phosphatase domain (amino acids 659-909) that is 35-40% identical to previously described tyrosine-phosphatase domains. The recombinant phosphatase domain possesses protein-tyrosine-phosphatase activity when expressed in Escherichia coli. The amino-terminal region (amino acids 31-367) is 45% identical to the amino terminus of human erythrocyte protein 4.1, a cytoskeletal protein. The identification of a protein-tyrosine-phosphatase that is related to cytoskeletal proteins implies that cell signaling activities reside not only in transmembrane receptors but in cytoskeletal elements as well.
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Affiliation(s)
- M X Gu
- Washington University School of Medicine, Division of Hematology-Oncology, St. Louis, MO 63110
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New nucleotide sequence data on the EMBL File Server. Nucleic Acids Res 1991; 19:1731-6. [PMID: 2027787 PMCID: PMC333972 DOI: 10.1093/nar/19.7.1731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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