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Rameh LE, York JD, Blind RD. Multiple inositol phosphate species enhance stability of active mTOR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.01.592113. [PMID: 38746235 PMCID: PMC11092565 DOI: 10.1101/2024.05.01.592113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Mechanistic Target of Rapamycin (mTOR) binds the small metabolite inositol hexakisphosphate (IP6) as shown in structures of mTOR, however it remains unclear if IP6, or any other inositol phosphate species, can activate mTOR kinase activity. Here, we show that multiple, exogenously added inositol phosphate species (IP6, IP5, IP4 and IP3) can all enhance the ability of mTOR and mTORC1 to auto-phosphorylate and incorporate radiolabeled phosphate into peptide substrates in in vitro kinase reactions. Although IP6 did not affect the apparent KM of mTORC1 for ATP, monitoring kinase activity over longer reaction times showed increased product formation, suggesting inositol phosphates stabilize an active form of mTORC1 in vitro. The effects of IP6 on mTOR were reversible, suggesting IP6 bound to mTOR can be exchanged dynamically with the free solvent. Interestingly, we also observed that IP6 could alter mTOR solubility and electrophoretic mobility in SDS-PAGE in the presence of manganese, suggesting divalent cations may play a role in inositol phosphate regulation of mTOR. Together, these data suggest for the first time that multiple inositol phosphate species (IP4, IP5 and IP6) can dynamically regulate mTOR and mTORC1 by promoting a stable, active state of the kinase. Our data suggest that studies of the dynamics of inositol phosphate regulation of mTOR are well justified.
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Affiliation(s)
- Lucia E. Rameh
- University of South Alabama, Department of Biochemistry and Molecular Biology, Mobile, AL 36688
- Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, TN 37232
- Vanderbilt University Medical Center, Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Nashville, TN 37232
| | - John D. York
- Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, TN 37232
| | - Raymond D. Blind
- Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, TN 37232
- Vanderbilt University Medical Center, Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Nashville, TN 37232
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Sowd GA, Stivison EA, Chapagain P, Hale AT, Poland JC, Rameh LE, Blind RD. IPMK regulates HDAC3 activity and histone H4 acetylation in human cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.29.591660. [PMID: 38746349 PMCID: PMC11092501 DOI: 10.1101/2024.04.29.591660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Histone deacetylases (HDACs) repress transcription by catalyzing the removal of acetyl groups from histones. Class 1 HDACs are activated by inositol phosphate signaling molecules in vitro , but it is unclear if this regulation occurs in human cells. Inositol Polyphosphate Multikinase (IPMK) is required for production of inositol hexakisphosphate (IP6), pentakisphosphate (IP5) and certain tetrakisphosphate (IP4) species, all known activators of Class 1 HDACs in vitro . Here, we generated IPMK knockout (IKO) human U251 glioblastoma cells, which decreased cellular inositol phosphate levels and increased histone H4-acetylation by mass spectrometry. ChIP-seq showed IKO increased H4-acetylation at IKO-upregulated genes, but H4-acetylation was unchanged at IKO-downregulated genes, suggesting gene-specific responses to IPMK knockout. HDAC deacetylase enzyme activity was decreased in HDAC3 immunoprecipitates from IKO vs . wild-type cells, while deacetylase activity of other Class 1 HDACs had no detectable changes in activity. Wild-type IPMK expression in IKO cells fully rescued HDAC3 deacetylase activity, while kinase-dead IPMK expression had no effect. Further, the deficiency in HDAC3 activity in immunoprecipitates from IKO cells could be fully rescued by addition of synthesized IP4 (Ins(1,4,5,6)P4) to the enzyme assay, while control inositol had no effect. These data suggest that cellular IPMK-dependent inositol phosphates are required for full HDAC3 enzyme activity and proper histone H4-acetylation. Implications for targeting IPMK in HDAC3-dependent diseases are discussed.
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Pullagurla NJ, Shome S, Yadav R, Laha D. ITPK1 Regulates Jasmonate-Controlled Root Development in Arabidopsis thaliana. Biomolecules 2023; 13:1368. [PMID: 37759768 PMCID: PMC10526342 DOI: 10.3390/biom13091368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 08/26/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Jasmonic acid (JA) is a plant hormone that regulates a plethora of physiological processes including immunity and development and is perceived by the F-Box protein, Coronatine-insensitive protein 1 (COI1). The discovery of inositol phosphates (InsPs) in the COI1 receptor complex highlights their role in JAperception. InsPs are phosphate-rich signaling molecules that control many aspects of plant physiology. Inositol pyrophosphates (PP-InsPs) are diphosphate containing InsP species, of which InsP7 and InsP8 are the best characterized ones. Different InsP and PP-InsP species are linked with JA-related plant immunity. However, role of PP-InsP species in regulating JA-dependent developmental processes are poorly understood. Recent identification of ITPK1 kinase, responsible for the production of 5-InsP7 from InsP6in planta, provides a platform to investigate the possible involvement of ITPK-derived InsP species in JA-related plant development. Here, in this study, we report that ITPK1-defective plants exhibit increased root growth inhibition to bioactive JA treatment. The itpk1 plants also show increased lateral root density when treated with JA. Notably, JA treatment does not increase ITPK1 protein levels. Gene expression analyses revealed that JA-biosynthetic genes are not differentially expressed in ITPK1-deficient plants. We further demonstrate that genes encoding different JAZ repressor proteins are severely down-regulated in ITPK1-defective plants. Taken together, our study highlights the role of ITPK1 in regulating JA-dependent root architecture development through controlling the expression of different JAZ repressor proteins.
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Affiliation(s)
| | | | | | - Debabrata Laha
- Department of Biochemistry, Division of Biological Sciences, Indian Institute of Science (IISc), Bengaluru 560012, India; (N.J.P.); (S.S.); (R.Y.)
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Kanemaru K, Nakamura Y. Activation Mechanisms and Diverse Functions of Mammalian Phospholipase C. Biomolecules 2023; 13:915. [PMID: 37371495 DOI: 10.3390/biom13060915] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 05/28/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
Phospholipase C (PLC) plays pivotal roles in regulating various cellular functions by metabolizing phosphatidylinositol 4,5-bisphosphate in the plasma membrane. This process generates two second messengers, inositol 1,4,5-trisphosphate and diacylglycerol, which respectively regulate the intracellular Ca2+ levels and protein kinase C activation. In mammals, six classes of typical PLC have been identified and classified based on their structure and activation mechanisms. They all share X and Y domains, which are responsible for enzymatic activity, as well as subtype-specific domains. Furthermore, in addition to typical PLC, atypical PLC with unique structures solely harboring an X domain has been recently discovered. Collectively, seven classes and 16 isozymes of mammalian PLC are known to date. Dysregulation of PLC activity has been implicated in several pathophysiological conditions, including cancer, cardiovascular diseases, and neurological disorders. Therefore, identification of new drug targets that can selectively modulate PLC activity is important. The present review focuses on the structures, activation mechanisms, and physiological functions of mammalian PLC.
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Affiliation(s)
- Kaori Kanemaru
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan
| | - Yoshikazu Nakamura
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan
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Gulabani H, Goswami K, Walia Y, Roy A, Noor JJ, Ingole KD, Kasera M, Laha D, Giehl RFH, Schaaf G, Bhattacharjee S. Arabidopsis inositol polyphosphate kinases IPK1 and ITPK1 modulate crosstalk between SA-dependent immunity and phosphate-starvation responses. PLANT CELL REPORTS 2022; 41:347-363. [PMID: 34797387 DOI: 10.1007/s00299-021-02812-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/04/2021] [Indexed: 05/27/2023]
Abstract
KEY MESSAGE Selective Arabidopsis thaliana inositol phosphate kinase functions modulate response amplitudes in innate immunity by balancing signalling adjustments with phosphate homeostasis networks. Pyrophosphorylation of InsP6 generates InsP7 and/or InsP8 containing high-energy phosphoanhydride bonds that are harnessed during energy requirements of a cell. As bona fide co-factors for several phytohormone networks, InsP7/InsP8 modulate key developmental processes. With requirements in transducing jasmonic acid (JA) and phosphate-starvation responses (PSR), InsP8 exemplifies a versatile metabolite for crosstalks between different cellular pathways during diverse stress exposures. Here we show that Arabidopsis thaliana INOSITOL PENTAKISPHOSPHATE 2-KINASE 1 (IPK1), INOSITOL 1,3,4-TRISPHOSPHATE 5/6-KINASE 1 (ITPK1), and DIPHOSPHOINOSITOL PENTAKISPHOSPHATE KINASE 2 (VIH2) implicated in InsP8 biosynthesis, suppress salicylic acid (SA)-dependent immunity. In ipk1, itpk1 or vih2 mutants, constitutive activation of defenses lead to enhanced resistance against the Pseudomonas syringae pv tomato DC3000 (PstDC3000) strain. Our data reveal that upregulated SA-signaling sectors potentiate increased expression of several phosphate-starvation inducible (PSI)-genes, previously known in these mutants. In reciprocation, upregulated PSI-genes moderate expression amplitudes of defense-associated markers. We demonstrate that SA is induced in phosphate-deprived plants, however its defense-promoting functions are likely diverted to PSR-supportive roles. Overall, our investigations reveal selective InsPs as crosstalk mediators in defense-phosphate homeostasis and in reprogramming stress-appropriate response intensities.
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Affiliation(s)
- Hitika Gulabani
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
- Manipal Academy of Higher Education (MAHE), Manipal University, Manipal, Karnataka, 576104, India
| | - Krishnendu Goswami
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
| | - Yashika Walia
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
| | - Abhisha Roy
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
| | - Jewel Jameeta Noor
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
| | - Kishor D Ingole
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
- Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar, Odisha, 751024, India
| | - Mritunjay Kasera
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
| | - Debabrata Laha
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, 560 012, India
| | - Ricardo F H Giehl
- Department of Physiology and Cell Biology, Leibniz-Institute of Plant Genetics and Crop Plant Research, 06466, Gatersleben, Germany
| | - Gabriel Schaaf
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115, Bonn, Germany
| | - Saikat Bhattacharjee
- Laboratory of Signal Transduction and Plant Resistance, UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India.
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Unconventional metabolites in chromatin regulation. Biosci Rep 2022; 42:230604. [PMID: 34988581 PMCID: PMC8777195 DOI: 10.1042/bsr20211558] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 01/04/2022] [Accepted: 01/04/2022] [Indexed: 11/17/2022] Open
Abstract
Chromatin, the complex of DNA and histone proteins, serves as a main integrator of cellular signals. Increasing evidence links cellular functional to chromatin state. Indeed, different metabolites are emerging as modulators of chromatin function and structure. Alterations in chromatin state are decisive for regulating all aspects of genome function and ultimately have the potential to produce phenotypic changes. Several metabolites such as acetyl-CoA, S-adenosylmethionine (SAM) or adenosine triphosphate (ATP) have now been well characterized as main substrates or cofactors of chromatin-modifying enzymes. However, there are other metabolites that can directly interact with chromatin influencing its state or that modulate the properties of chromatin regulatory factors. Also, there is a growing list of atypical enzymatic and nonenzymatic chromatin modifications that originate from different cellular pathways that have not been in the limelight of chromatin research. Here, we summarize different properties and functions of uncommon regulatory molecules originating from intermediate metabolism of lipids, carbohydrates and amino acids. Based on the various modes of action on chromatin and the plethora of putative, so far not described chromatin-regulating metabolites, we propose that there are more links between cellular functional state and chromatin regulation to be discovered. We hypothesize that these connections could provide interesting starting points for interfering with cellular epigenetic states at a molecular level.
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Li CW, Sachidanandam R, Jayaprakash A, Yi Z, Zhang W, Stefan-Lifshitz M, Concepcion E, Tomer Y. Identification of New Rare Variants Associated With Familial Autoimmune Thyroid Diseases by Deep Sequencing of Linked Loci. J Clin Endocrinol Metab 2021; 106:e4680-e4687. [PMID: 34143178 PMCID: PMC8530708 DOI: 10.1210/clinem/dgab440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Indexed: 11/19/2022]
Abstract
CONTEXT Genetic risk factors play a major role in the pathoetiology of autoimmune thyroid diseases (AITD). So far, only common risk variants have been identified in AITD susceptibility genes. Recently, rare genetic variants have emerged as important contributors to complex diseases, and we hypothesized that rare variants play a key role in the genetic susceptibility to AITD. OBJECTIVE We aimed to identify new rare variants that are associated with familial AITD. METHODS We performed deep sequencing of 3 previously mapped AITD-linked loci (10q, 12q, and 14q) in a dataset of 34 families in which AITD clustered (familial AITD). RESULTS We identified 13 rare variants, located in the inositol polyphosphate multikinase (IPMK) gene, that were associated with AITD (ie, both Graves' disease [GD] and Hashimoto's thyroiditis [HT]); 2 rare variants, within the dihydrolipoamide S-succinyltransferase (DLST) and zinc-finger FYVE domain-containing protein (ZFYVE1) genes, that were associated with GD only; and 3 rare variants, within the phosphoglycerate mutase 1 pseudogene 5 (PGAM1P5), LOC105369879, and methionine aminopeptidase 2 (METAP2) genes, that were associated with HT only. CONCLUSION Our study demonstrates that, in addition to common variants, rare variants also contribute to the genetic susceptibility to AITD. We identified new rare variants in 6 AITD susceptibility genes that predispose to familial AITD. Of these, 3 genes, IPMK, ZFYVE1, and METAP2, are mechanistically involved in immune pathways and have been previously shown to be associated with autoimmunity. These genes predispose to thyroid autoimmunity and may serve as potential therapeutic targets in the future.
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Affiliation(s)
- Cheuk Wun Li
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ravi Sachidanandam
- Department of Oncological Sciences, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Anitha Jayaprakash
- Department of Oncological Sciences, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Zhengzi Yi
- Department of Medicine Bioinformatics Core, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Weijia Zhang
- Department of Medicine Bioinformatics Core, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | | | - Erlinda Concepcion
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Yaron Tomer
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: Yaron Tomer, MD, Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, NY 10461, USA.
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Aiken C, Rousso I. The HIV-1 capsid and reverse transcription. Retrovirology 2021; 18:29. [PMID: 34563203 PMCID: PMC8466977 DOI: 10.1186/s12977-021-00566-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 07/20/2021] [Indexed: 02/08/2023] Open
Abstract
The viral capsid plays a key role in HIV-1 reverse transcription. Recent studies have demonstrated that the small molecule IP6 dramatically enhances reverse transcription in vitro by stabilizing the viral capsid. Reverse transcription results in marked changes in the biophysical properties of the capsid, ultimately resulting in its breakage and disassembly. Here we review the research leading to these advances and describe hypotheses for capsid-dependent HIV-1 reverse transcription and a model for reverse transcription-primed HIV-1 uncoating.
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Affiliation(s)
- Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Itay Rousso
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel
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A Structural Perspective of the Role of IP6 in Immature and Mature Retroviral Assembly. Viruses 2021; 13:v13091853. [PMID: 34578434 PMCID: PMC8473085 DOI: 10.3390/v13091853] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/10/2021] [Accepted: 09/12/2021] [Indexed: 11/17/2022] Open
Abstract
The small cellular molecule inositol hexakisphosphate (IP6) has been known for ~20 years to promote the in vitro assembly of HIV-1 into immature virus-like particles. However, the molecular details underlying this effect have been determined only recently, with the identification of the IP6 binding site in the immature Gag lattice. IP6 also promotes formation of the mature capsid protein (CA) lattice via a second IP6 binding site, and enhances core stability, creating a favorable environment for reverse transcription. IP6 also enhances assembly of other retroviruses, from both the Lentivirus and the Alpharetrovirus genera. These findings suggest that IP6 may have a conserved function throughout the family Retroviridae. Here, we discuss the different steps in the viral life cycle that are influenced by IP6, and describe in detail how IP6 interacts with the immature and mature lattices of different retroviruses.
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Pramitha JL, Rana S, Aggarwal PR, Ravikesavan R, Joel AJ, Muthamilarasan M. Diverse role of phytic acid in plants and approaches to develop low-phytate grains to enhance bioavailability of micronutrients. ADVANCES IN GENETICS 2020; 107:89-120. [PMID: 33641749 DOI: 10.1016/bs.adgen.2020.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Natural or synthetic compounds that interfere with the bioavailability of nutrients are called antinutrients. Phytic acid (PA) is one of the major antinutrients present in the grains and acts as a chelator of micronutrients. The presence of six reactive phosphate groups in PA hinders the absorption of micronutrients in the gut of non-ruminants. Consumption of PA-rich diet leads to deficiency of minerals such as iron and zinc among human population. On the contrary, PA is a natural antioxidant, and PA-derived molecules function in various signal transduction pathways. Therefore, optimal concentration of PA needs to be maintained in plants to avoid adverse pleiotropic effects, as well as to ensure micronutrient bioavailability in the diets. Given this, the chapter enumerates the structure, biosynthesis, and accumulation of PA in food grains followed by their roles in growth, development, and stress responses. Further, the chapter elaborates on the antinutritional properties of PA and explains the conventional breeding and transgene-based approaches deployed to develop low-PA varieties. Studies have shown that conventional breeding methods could develop low-PA lines; however, the pleiotropic effects of these methods viz. reduced yield, embryo abnormalities, and poor seed quality hinder the use of breeding strategies. Overexpression of phytase in the endosperm and RNAi-mediated silencing of genes involved in myo-inositol biosynthesis overcome these constraints. Next-generation genome editing approaches, including CRISPR-Cas9 enable the manipulation of more than one gene involved in PA biosynthesis pathway through multiplex editing, and scope exists to deploy such tools in developing varieties with optimal PA levels.
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Affiliation(s)
- J Lydia Pramitha
- Department of Millets, Center for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India
| | - Sumi Rana
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India
| | - Pooja Rani Aggarwal
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India
| | - Rajasekaran Ravikesavan
- Department of Millets, Center for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
| | - A John Joel
- Tamil Nadu Rice Research Institute, Tamil Nadu Agricultural University, Aduthurai, Tamil Nadu, India
| | - Mehanathan Muthamilarasan
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India.
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The Host Cell Metabolite Inositol Hexakisphosphate Promotes Efficient Endogenous HIV-1 Reverse Transcription by Stabilizing the Viral Capsid. mBio 2020; 11:mBio.02820-20. [PMID: 33262260 PMCID: PMC7733946 DOI: 10.1128/mbio.02820-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
HIV-1 infection requires reverse transcription of the viral genome. While much is known about the biochemistry of reverse transcription from simplified biochemical reactions, reverse transcription during infection takes place within a viral core. However, endogenous reverse transcription reactions using permeabilized HIV-1 virions or purified viral cores have been inefficient. Using viral cores purified from infectious HIV-1 particles, we show that efficient reverse transcription is achieved in vitro by addition of the capsid-stabilizing metabolite inositol hexakisphosphate. The enhancement of reverse transcription was linked to the capsid-stabilizing effect of the compound, consistent with the known requirement for an intact or semi-intact viral capsid for HIV-1 infection. Our results establish a biologically relevant system for dissecting the function of the viral capsid and its disassembly during reverse transcription. The system should also prove useful for mechanistic studies of capsid-targeting antiviral drugs. A defining activity of retroviruses is reverse transcription, the process by which the viral genomic RNA is converted into the double-stranded DNA required for virus replication. Reverse transcriptase (RT), the viral enzyme responsible for this process, was identified in 1970 by assaying permeabilized retrovirus particles for DNA synthesis in vitro. Such reactions are inefficient, with only a small fraction of viral genomes being converted to full-length double-stranded DNA molecules, possibly owing to disruption of the structure of the viral core. Here, we show that reverse transcription in purified HIV-1 cores is enhanced by the addition of the capsid-binding host cell metabolite inositol hexakisphosphate (IP6). IP6 potently enhanced full-length minus-strand synthesis, as did hexacarboxybenzene (HCB), which also stabilizes the HIV-1 capsid. Both IP6 and HCB stabilized the association of the viral CA and RT proteins with HIV-1 cores. In contrast to the wild type, cores isolated from mutant HIV-1 particles containing intrinsically hyperstable capsids exhibited relatively efficient reverse transcription in the absence of IP6, further indicating that the compound promotes reverse transcription by stabilizing the viral capsid. We also observed that the capsid-destabilizing antiviral compound PF74 inhibited endogenous reverse transcription with a potency that mirrors its ability to inhibit reverse transcription during infection. Our results show that the stabilization of the HIV-1 capsid permits efficient reverse transcription in HIV-1 cores, providing a sensitive experimental system for analyzing the functions of viral and host cell molecules and the role of capsid disassembly (uncoating) in the process.
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Yang ZL, Chen JN, Lu YY, Lu M, Wan QL, Wu GS, Luo HR. Inositol polyphosphate multikinase IPMK-1 regulates development through IP3/calcium signaling in Caenorhabditis elegans. Cell Calcium 2020; 93:102327. [PMID: 33316585 DOI: 10.1016/j.ceca.2020.102327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/25/2020] [Accepted: 11/27/2020] [Indexed: 01/17/2023]
Abstract
Inositol polyphosphate multikinase (IPMK) is a conserved protein that initiates the production of inositol phosphate intracellular messengers and is critical for regulating a variety of cellular processes. Here, we report that the C. elegans IPMK-1, which is homologous to the mammalian inositol polyphosphate multikinase, plays a crucial role in regulating rhythmic behavior and development. The deletion mutant ipmk-1(tm2687) displays a long defecation cycle period and retarded postembryonic growth. The expression of functional ipmk-1::GFP was detected in the pharyngeal muscles, amphid sheath cells, the intestine, excretory (canal) cells, proximal gonad, and spermatheca. The expression of IPMK-1 in the intestine was sufficient for the wild-type phenotype. The IP3-kinase activity of IPMK-1 is required for defecation rhythms and postembryonic development. The defective phenotypes of ipmk-1(tm2687) could be rescued by a loss-of-function mutation in type I inositol 5-phosphatase homolog (IPP-5) and improved by a supplemental Ca2+ in the medium. Our work demonstrates that IPMK-1 and the signaling molecule inositol triphosphate (IP3) pathway modulate rhythmic behaviors and development by dynamically regulating the concentration of intracellular Ca2+ in C. elegans. Advances in understanding the molecular regulation of Ca2+ homeostasis and regulation of organism development may lead to therapeutic strategies that modulate Ca2+ signaling to enhance function and counteract disease processes. Unraveling the physiological role of IPMK and the underlying functional mechanism in C. elegans would contribute to understanding the role of IPMK in other species, especially in mammals, and benefit further research on the involvement of IPMK in disease.
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Affiliation(s)
- Zhong-Lin Yang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Graduate University of the Chinese Academy of Science, Beijing, 100049, China
| | - Jian-Ning Chen
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Yu-Yang Lu
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Min Lu
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Qin-Li Wan
- The Center for Precision Medicine of First Affiliated Hospital, Biomedical Translational Research Institute, Jinan University, Guangzhou, Guangdong 510632, China
| | - Gui-Sheng Wu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
| | - Huai-Rong Luo
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Graduate University of the Chinese Academy of Science, Beijing, 100049, China; Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
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13
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Minini M, Senni A, Unfer V, Bizzarri M. The Key Role of IP 6K: A Novel Target for Anticancer Treatments? Molecules 2020; 25:molecules25194401. [PMID: 32992691 PMCID: PMC7583815 DOI: 10.3390/molecules25194401] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 12/29/2022] Open
Abstract
Inositol and its phosphate metabolites play a pivotal role in several biochemical pathways and gene expression regulation: inositol pyrophosphates (PP-IPs) have been increasingly appreciated as key signaling modulators. Fluctuations in their intracellular levels hugely impact the transfer of phosphates and the phosphorylation status of several target proteins. Pharmacological modulation of the proteins associated with PP-IP activities has proved to be beneficial in various pathological settings. IP7 has been extensively studied and found to play a key role in pathways associated with PP-IP activities. Three inositol hexakisphosphate kinase (IP6K) isoforms regulate IP7 synthesis in mammals. Genomic deletion or enzymic inhibition of IP6K1 has been shown to reduce cell invasiveness and migration capacity, protecting against chemical-induced carcinogenesis. IP6K1 could therefore be a useful target in anticancer treatment. Here, we summarize the current understanding that established IP6K1 and the other IP6K isoforms as possible targets for cancer therapy. However, it will be necessary to determine whether pharmacological inhibition of IP6K is safe enough to begin clinical study. The development of safe and selective inhibitors of IP6K isoforms is required to minimize undesirable effects.
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Affiliation(s)
- Mirko Minini
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Department of Surgery ‘P. Valdoni’, Sapienza University of Rome, 00161 Rome, Italy
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.M.); (M.B.)
| | - Alice Senni
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Department of Surgery ‘P. Valdoni’, Sapienza University of Rome, 00161 Rome, Italy
| | - Vittorio Unfer
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
| | - Mariano Bizzarri
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.M.); (M.B.)
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14
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Ricana CL, Lyddon TD, Dick RA, Johnson MC. Primate lentiviruses require Inositol hexakisphosphate (IP6) or inositol pentakisphosphate (IP5) for the production of viral particles. PLoS Pathog 2020; 16:e1008646. [PMID: 32776974 PMCID: PMC7446826 DOI: 10.1371/journal.ppat.1008646] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/20/2020] [Accepted: 06/26/2020] [Indexed: 11/18/2022] Open
Abstract
Inositol hexakisphosphate (IP6) potently stimulates HIV-1 particle assembly in vitro and infectious particle production in vivo. However, knockout cells lacking inositol-pentakisphosphate 2-kinase (IPPK-KO), the enzyme that produces IP6 by phosphorylation of inositol pentakisphosphate (IP5), were still able to produce infectious HIV-1 particles at a greatly reduced rate. HIV-1 in vitro assembly can also be stimulated to a lesser extent with IP5, but until recently, it was not known if IP5 could also function in promoting assembly in vivo. Here we addressed whether there is an absolute requirement for IP6 or IP5 in the production of infectious HIV-1 particles. IPPK-KO cells expressed no detectable IP6 but elevated IP5 levels and displayed a 20-100-fold reduction in infectious particle production, correlating with lost virus release. Transient transfection of an IPPK expression vector stimulated infectious particle production and release in IPPK-KO but not wildtype cells. Several attempts to make IP6/IP5 deficient stable cells were not successful, but transient expression of the enzyme multiple inositol polyphosphate phosphatase-1 (MINPP1) into IPPK-KOs resulted in near ablation of IP6 and IP5. Under these conditions, we found that HIV-1 infectious particle production and virus release were essentially abolished (1000-fold reduction) demonstrating an IP6/IP5 requirement. However, other retroviruses including a Gammaretrovirus, a Betaretrovirus, and two non-primate Lentiviruses displayed only a modest (3-fold) reduction in infectious particle production from IPPK-KOs and were not significantly altered by expression of IPPK or MINPP1. The only other retrovirus found to show a clear IP6/IP5 dependence was the primate (macaque) Lentivirus Simian Immunodeficiency Virus, which displayed similar sensitivity as HIV-1. We were not able to determine if producer cell IP6/IP5 is required at additional steps beyond assembly because viral particles devoid of both molecules could not be generated. Finally, we found that loss of IP6/IP5 in viral target cells had no effect on permissivity to HIV-1 infection.
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Affiliation(s)
- Clifton L Ricana
- Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Terri D Lyddon
- Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Robert A Dick
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Marc C Johnson
- Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
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15
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Wang FX, Chen K, Huang FQ, Alolga RN, Ma J, Wu ZX, Fan Y, Ma G, Guan M. Cerebrospinal fluid-based metabolomics to characterize different types of brain tumors. J Neurol 2019; 267:984-993. [PMID: 31822990 DOI: 10.1007/s00415-019-09665-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/30/2019] [Accepted: 12/03/2019] [Indexed: 12/23/2022]
Abstract
BACKGROUND Brain tumors cause significant morbidity and mortality due to rapid progression and high recurrence risks. Reliable biomarkers to improve diagnosis thereof are desirable. OBJECTIVE This work aimed to identify panels of biomarkers for diagnostic purposes using cerebrospinal fluid (CSF)-based metabolomics. METHODS A cohort of 163 histologically-proven patients with brain disorders was involved. Comprehensive CSF-based metabolomics was achieved by liquid chromatography-quadrupole time-of-flight spectrometric (LC-Q/TOF-MS) and multivariate statistical analyses. The diagnostic performance of the metabolic markers was evaluated using receiver operating characteristic curves. RESULTS A total of 508 ion features were detected by the LC-Q/TOF-MS analysis, of which 27 metabolites were selected as diagnostic markers to discriminate different brain tumor types. The area under the curve (AUC) was 0.91 for lung adenocarcinoma patients with brain metastases (MBT) vs. lung adenocarcinoma patients without brain metastases (NMBT), 0.83 for primary central nervous system lymphoma (PCNSL) vs. secondary central nervous system involvement of systemic lymphoma (SCNSL), 0.77 for PCNSL vs. MBT, 0.87 for SCNSL vs. MBT, 0.86 for MBT vs. nontumorous brain diseases (NT), and 0.80 for PCNSL vs. NT. Perturbed metabolic pathways between the comparisons related mainly to amino acids and citrate metabolism. CONCLUSIONS CSF-based metabolomics to a large extent reliably identifies significant metabolic differences between different brain tumors and shows great potential for diagnosis of brain tumors.
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Affiliation(s)
- Feng-Xiang Wang
- Clinical Metabolomics Center, China Pharmaceutical University, 639 Longmian Avenue, Jiangning District, Nanjing, China
| | - Kun Chen
- Department of Clinical Laboratory, North Huashan Hospital, Fudan University, Shanghai, China
| | - Feng-Qing Huang
- Clinical Metabolomics Center, China Pharmaceutical University, 639 Longmian Avenue, Jiangning District, Nanjing, China
| | - Raphael N Alolga
- Clinical Metabolomics Center, China Pharmaceutical University, 639 Longmian Avenue, Jiangning District, Nanjing, China
| | - Jingjing Ma
- Department of Hematology, North Huashan Hospital, Fudan University, Shanghai, China
| | - Zi-Xuan Wu
- Clinical Metabolomics Center, China Pharmaceutical University, 639 Longmian Avenue, Jiangning District, Nanjing, China
| | - Yuanming Fan
- Clinical Metabolomics Center, China Pharmaceutical University, 639 Longmian Avenue, Jiangning District, Nanjing, China
| | - Gaoxiang Ma
- Clinical Metabolomics Center, China Pharmaceutical University, 639 Longmian Avenue, Jiangning District, Nanjing, China.
| | - Ming Guan
- Central Laboratory, Huashan Hospital, Fudan University, 108 Luxiang Avenue, Baoshan District, Shanghai, China.
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16
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Clarke BP, Logeman BL, Hale AT, Luka Z, York JD. A synthetic biological approach to reconstitution of inositide signaling pathways in bacteria. Adv Biol Regul 2019; 73:100637. [PMID: 31378699 DOI: 10.1016/j.jbior.2019.100637] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 11/19/2022]
Abstract
Inositide lipid (PIP) and soluble (IP) signaling pathways produce essential cellular codes conserved in eukaryotes. In many cases, deconvoluting metabolic and functional aspects of individual pathways are confounded by promiscuity and multiplicity of PIP and IP kinases and phosphatases. We report a molecular genetic approach that reconstitutes eukaryotic inositide lipid and soluble pathways in a prokaryotic cell which inherently lack inositide kinases and phosphatases in their genome. By expressing synthetic cassettes of eukaryotic genes, we have reconstructed the heterologous formation of a range of inositide lipids, including PI(3)P, PI(4,5)P2 and PIP3. In addition, we report the reconstruction of lipid-dependent production of inositol hexakisphosphate (IP6). Our synthetic system is scalable, reduces confounding metabolic issues, for example it is devoid of inositide phosphatases and orthologous kinases, and enables accurate characterization gene product enzymatic activity and substrate selectivity. This genetically engineered tool is designed to help interpret metabolic pathways and may facilitate in vivo testing of regulators and small molecule inhibitors. In summary, heterologous expression of inositide pathways in bacteria provide a malleable experimental platform for aiding signaling biologists and offers new insights into metabolism of these essential pathways.
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Affiliation(s)
- Bradley P Clarke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brandon L Logeman
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA
| | - Andrew T Hale
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Zigmund Luka
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - John D York
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
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17
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Nuclear Phosphoinositides: Their Regulation and Roles in Nuclear Functions. Int J Mol Sci 2019; 20:ijms20122991. [PMID: 31248120 PMCID: PMC6627530 DOI: 10.3390/ijms20122991] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/22/2019] [Accepted: 06/17/2019] [Indexed: 12/29/2022] Open
Abstract
Polyphosphoinositides (PPIns) are a family of seven lipid messengers that regulate a vast array of signalling pathways to control cell proliferation, migration, survival and differentiation. PPIns are differentially present in various sub-cellular compartments and, through the recruitment and regulation of specific proteins, are key regulators of compartment identity and function. Phosphoinositides and the enzymes that synthesise and degrade them are also present in the nuclear membrane and in nuclear membraneless compartments such as nuclear speckles. Here we discuss how PPIns in the nucleus are modulated in response to external cues and how they function to control downstream signalling. Finally we suggest a role for nuclear PPIns in liquid phase separations that are involved in the formation of membraneless compartments within the nucleus.
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18
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van Wijk R, Zhang Q, Zarza X, Lamers M, Marquez FR, Guardia A, Scuffi D, García-Mata C, Ligterink W, Haring MA, Laxalt AM, Munnik T. Role for Arabidopsis PLC7 in Stomatal Movement, Seed Mucilage Attachment, and Leaf Serration. FRONTIERS IN PLANT SCIENCE 2018; 9:1721. [PMID: 30542361 PMCID: PMC6278229 DOI: 10.3389/fpls.2018.01721] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/05/2018] [Indexed: 05/24/2023]
Abstract
Phospholipase C (PLC) has been suggested to play important roles in plant stress and development. To increase our understanding of PLC signaling in plants, we have started to analyze knock-out (KO), knock-down (KD) and overexpression mutants of Arabidopsis thaliana, which contains nine PLCs. Earlier, we characterized PLC2, PLC3 and PLC5. Here, the role of PLC7 is functionally addressed. Promoter-GUS analyses revealed that PLC7 is specifically expressed in the phloem of roots, leaves and flowers, and is also present in trichomes and hydathodes. Two T-DNA insertion mutants were obtained, i.e., plc7-3 being a KO- and plc7-4 a KD line. In contrast to earlier characterized phloem-expressed PLC mutants, i.e., plc3 and plc5, no defects in primary- or lateral root development were found for plc7 mutants. Like plc3 mutants, they were less sensitive to ABA during stomatal closure. Double-knockout plc3 plc7 lines were lethal, but plc5 plc7 (plc5/7) double mutants were viable, and revealed several new phenotypes, not observed earlier in the single mutants. These include a defect in seed mucilage, enhanced leaf serration, and an increased tolerance to drought. Overexpression of PLC7 enhanced drought tolerance too, similar to what was earlier found for PLC3-and PLC5 overexpression. In vivo 32Pi-labeling of seedlings and treatment with sorbitol to mimic drought stress, revealed stronger PIP2 responses in both drought-tolerant plc5/7 and PLC7-OE mutants. Together, these results show novel functions for PLC in plant stress and development. Potential molecular mechanisms are discussed.
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Affiliation(s)
- Ringo van Wijk
- Section Plant Physiology, University of Amsterdam, Amsterdam, Netherlands
- Section Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Amsterdam, Netherlands
| | - Qianqian Zhang
- Section Plant Physiology, University of Amsterdam, Amsterdam, Netherlands
- Section Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Amsterdam, Netherlands
| | - Xavier Zarza
- Section Plant Physiology, University of Amsterdam, Amsterdam, Netherlands
- Section Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Amsterdam, Netherlands
| | - Mart Lamers
- Section Plant Physiology, University of Amsterdam, Amsterdam, Netherlands
| | | | - Aisha Guardia
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Denise Scuffi
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Carlos García-Mata
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Wilco Ligterink
- Laboratory of Plant Physiology, Wageningen University and Research, Wageningen, Netherlands
| | - Michel A. Haring
- Section Plant Physiology, University of Amsterdam, Amsterdam, Netherlands
| | - Ana M. Laxalt
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Teun Munnik
- Section Plant Physiology, University of Amsterdam, Amsterdam, Netherlands
- Section Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Amsterdam, Netherlands
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19
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Mutlu N, Kumar A. Messengers for morphogenesis: inositol polyphosphate signaling and yeast pseudohyphal growth. Curr Genet 2018; 65:119-125. [PMID: 30101372 DOI: 10.1007/s00294-018-0874-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/06/2018] [Accepted: 08/07/2018] [Indexed: 12/20/2022]
Abstract
In response to various environmental stimuli and stressors, the budding yeast Saccharomyces cerevisiae can initiate a striking morphological transition from its classic growth mode as isolated single cells to a filamentous form in which elongated cells remain connected post-cytokinesis in multi-cellular pseudohyphae. The formation of pseudohyphal filaments is regulated through an expansive signaling network, encompassing well studied and highly conserved pathways enabling changes in cell polarity, budding, cytoskeletal organization, and cell adhesion; however, changes in metabolite levels underlying the pseudohyphal growth transition are less well understood. We have recently identified a function for second messenger inositol polyphosphates (InsPs) in regulating pseudohyphal growth. InsPs are formed through the cleavage of membrane-bound phosphatidylinositol 4,5-bisphosphate (PIP2), and these soluble compounds are now being appreciated as important regulators of diverse processes, from phosphate homeostasis to cell migration. We find that kinases in the InsP pathway are required for wild-type pseudohyphal growth, and that InsP species exhibit characteristic profiles under conditions promoting filamentation. Ratios of the doubly phosphorylated InsP7 isoforms 5PP-InsP5 to 1PP-InsP5 are elevated in mutants exhibiting exaggerated pseudohyphal growth. Interestingly, S. cerevisiae mutants deleted of the mitogen-activated protein kinases (MAPKs) Kss1p or Fus3p or the AMP-activated kinase (AMPK) family member Snf1p display mutant InsP profiles, suggesting that these signaling pathways may contribute to the regulatory mechanism controlling InsP levels. Consequently, analyses of yeast pseudohyphal growth may be informative in identifying mechanisms regulating InsPs, while indicating a new function for these conserved second messengers in modulating cell stress responses and morphogenesis.
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Affiliation(s)
- Nebibe Mutlu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Anuj Kumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
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20
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Phospholipids and inositol phosphates linked to the epigenome. Histochem Cell Biol 2018; 150:245-253. [DOI: 10.1007/s00418-018-1690-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2018] [Indexed: 12/17/2022]
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21
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Riley AM, Unterlass JE, Konieczny V, Taylor CW, Helleday T, Potter BVL. A synthetic diphosphoinositol phosphate analogue of inositol trisphosphate. MEDCHEMCOMM 2018; 9:1105-1113. [PMID: 30079174 PMCID: PMC6071853 DOI: 10.1039/c8md00149a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/01/2018] [Indexed: 01/17/2023]
Abstract
Diphosphoinositol phosphates (PP-InsPs) are inositol phosphates (InsPs) that contain PP (diphosphate) groups. Converting a phosphate group in an InsP into a diphosphate has been reported to enhance affinity for some binding proteins. We synthesised 1-PP-Ins(4,5)P2, the first diphosphate analogue of the intracellular signalling molecule InsP3, and examined its effects on InsP3 receptors, which are intracellular Ca2+ channels. 1-PP-Ins(4,5)P2 was indistinguishable from InsP3 in its ability to bind to and activate type 1 InsP3 receptors, indicating that the diphosphate modification of InsP3 affected neither affinity nor efficacy. Nevertheless, 1-PP-Ins(4,5)P2 is the most potent 1-phosphate modified analogue of InsP3 yet identified. PP-InsPs are generally hydrolysed by diphosphoinositol phosphate phosphohydrolases (DIPPs), but 1-PP-Ins(4,5)P2 was not readily metabolised by human DIPPs. Differential scanning fluorimetry showed that 1-PP-Ins(4,5)P2 stabilises DIPP proteins, but to a lesser extent than naturally occurring substrates 1-PP-InsP5 and 5-PP-InsP5. The non-hydrolysable InsP7 analogues 1-PCP-InsP5 and 5-PCP-InsP5 showed comparable stabilising abilities to their natural counterparts and may therefore be promising substrate analogues for co-crystallisation with DIPPs.
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Affiliation(s)
- Andrew M. Riley
- Medicinal Chemistry and Drug Discovery
, Department of Pharmacology
, University of Oxford
,
Mansfield Road
, Oxford OX1 3QT
, UK
.
; Fax: +44 (0)1865 271853
; Tel: +44 (0)1865 271945
| | - Judith E. Unterlass
- Science for Life Laboratory
, Department of Oncology-Pathology
, Karolinska Institutet
,
SE-171 21 Solna
, Sweden
| | - Vera Konieczny
- Department of Pharmacology
, University of Cambridge
,
Tennis Court Road
, Cambridge CB2 1PD
, UK
| | - Colin W. Taylor
- Department of Pharmacology
, University of Cambridge
,
Tennis Court Road
, Cambridge CB2 1PD
, UK
| | - Thomas Helleday
- Science for Life Laboratory
, Department of Oncology-Pathology
, Karolinska Institutet
,
SE-171 21 Solna
, Sweden
| | - Barry V. L. Potter
- Medicinal Chemistry and Drug Discovery
, Department of Pharmacology
, University of Oxford
,
Mansfield Road
, Oxford OX1 3QT
, UK
.
; Fax: +44 (0)1865 271853
; Tel: +44 (0)1865 271945
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22
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Norman KL, Shively CA, De La Rocha AJ, Mutlu N, Basu S, Cullen PJ, Kumar A. Inositol polyphosphates regulate and predict yeast pseudohyphal growth phenotypes. PLoS Genet 2018; 14:e1007493. [PMID: 29939992 PMCID: PMC6034902 DOI: 10.1371/journal.pgen.1007493] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 07/06/2018] [Accepted: 06/14/2018] [Indexed: 11/18/2022] Open
Abstract
Pseudohyphal growth is a nutrient-regulated program in which budding yeast form multicellular filaments of elongated and connected cells. Filamentous growth is required for virulence in pathogenic fungi and provides an informative model of stress-responsive signaling. The genetics and regulatory networks modulating pseudohyphal growth have been studied extensively, but little is known regarding the changes in metabolites that enable pseudohyphal filament formation. Inositol signaling molecules are an important class of metabolite messengers encompassing highly phosphorylated and diffusible inositol polyphosphates (InsPs). We report here that the InsP biosynthesis pathway is required for wild-type pseudohyphal growth. Under nitrogen-limiting conditions that can induce filamentation, InsPs exhibit characteristic profiles, distinguishing the InsP7 pyrophosphate isoforms 1PP-InsP5 and 5PP-InsP5. Deletion and overexpression analyses of InsP kinases identify elevated levels of 5PP-InsP5 relative to 1PP-InsP5 in mutants exhibiting hyper-filamentous growth. Overexpression of KCS1, which promotes formation of inositol pyrophosphates, is sufficient to drive pseudohyphal filamentation on medium with normal nitrogen levels. We find that the kinases Snf1p (AMPK), Kss1p, and Fus3p (MAPKs), required for wild-type pseudohyphal growth, are also required for wild-type InsP levels. Deletion analyses of the corresponding kinase genes indicate elevated InsP3 levels and an absence of exaggerated 5PP-InsP5 peaks in trace profiles from snf1Δ/Δ and kss1Δ/Δ mutants exhibiting decreased pseudohyphal filamentation. Elevated 5PP-InsP5:1PP-InsP5 ratios are present in the hyperfilamentous fus3 deletion mutant. Collectively, the data identify the presence of elevated 5PP-InsP5 levels relative to other inositol pyrophosphates as an in vivo marker of hyper-filamentous growth, while providing initial evidence for the regulation of InsP signaling by pseudohyphal growth kinases. Changes in metabolite levels underlie important biological processes, including cellular responses to nutrient stress. One such response encompasses the nitrogen stress-induced transition of budding yeast cells into multicellular filaments, relevant as a model of directional growth and fungal pathogenesis. We report here that a conserved family of charged lipid-derived metabolites, inositol polyphosphates, exhibits characteristic changes as yeast cell form filaments in response to conditions of nitrogen limitation. The ratios of doubly charged inositol pyrophosphates consistently match with the degree of filament formation. Enzymes of the inositol polyphosphate synthesis pathway are required for filament formation, and inositol polyphosphate levels are dependent on kinases that enable wild-type filamentation. Our data indicate that inositol polyphosphates mark filamentous growth states, highlighting a new regulatory role for these ubiquitous eukaryotic second messengers.
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Affiliation(s)
- Kaitlyn L. Norman
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Christian A. Shively
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Amberlene J. De La Rocha
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Nebibe Mutlu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sukanya Basu
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Paul J. Cullen
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Anuj Kumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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23
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Do inositol supplements enhance phosphatidylinositol supply and thus support endoplasmic reticulum function? Br J Nutr 2018; 120:301-316. [PMID: 29859544 DOI: 10.1017/s0007114518000946] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This review attempts to explain why consuming extra myoinositol (Ins), an essential component of membrane phospholipids, is often beneficial for patients with conditions characterised by insulin resistance, non-alcoholic fatty liver disease and endoplasmic reticulum (ER) stress. For decades we assumed that most human diets provide an adequate Ins supply, but newer evidence suggests that increasing Ins intake ameliorates several disorders, including polycystic ovary syndrome, gestational diabetes, metabolic syndrome, poor sperm development and retinopathy of prematurity. Proposed explanations often suggest functional enhancement of minor facets of Ins Biology such as insulin signalling through putative inositol-containing 'mediators', but offer no explanation for this selectivity. It is more likely that eating extra Ins corrects a deficiency of an abundant Ins-containing cell constituent, probably phosphatidylinositol (PtdIns). Much of a cell's PtdIns is in ER membranes, and an increase in ER membrane synthesis, enhancing the ER's functional capacity, is often an important part of cell responses to ER stress. This review: (a) reinterprets historical information on Ins deficiency as describing a set of events involving a failure of cells adequately to adapt to ER stress; (b) proposes that in the conditions that respond to dietary Ins there is an overstretching of Ins reserves that limits the stressed ER's ability to make the 'extra' PtdIns needed for ER membrane expansion; and (c) suggests that eating Ins supplements increases the Ins supply to Ins-deficient and ER-stressed cells, allowing them to make more PtdIns and to expand the ER membrane system and sustain ER functions.
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24
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Fu P, Ebenezer DL, Ha AW, Suryadevara V, Harijith A, Natarajan V. Nuclear lipid mediators: Role of nuclear sphingolipids and sphingosine-1-phosphate signaling in epigenetic regulation of inflammation and gene expression. J Cell Biochem 2018; 119:6337-6353. [PMID: 29377310 DOI: 10.1002/jcb.26707] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/23/2018] [Indexed: 12/18/2022]
Abstract
Phospholipids, sphingolipids, and cholesterol are integral components of eukaryotic cell organelles, including the nucleus. Recent evidence shows characteristic features of nuclear lipid composition and signaling, which are distinct from that of the cytoplasm and plasma membrane. While the nuclear phosphoinositol lipid signaling in cell cycle regulation and differentiation has been well described, there is a paucity on the role of nuclear sphingolipids and sphingolipid signaling in different physiological and pathophysiological human conditions. In this prospective, we describe the role of sphingolipids and specifically focus on the sphingoid bases, such as sphingosine, ceramide, and sphingosine-1-phosphate (S1P) generation and catabolism in nuclear signaling and function. Particularly, S1P generated in the nucleus by phosphorylation of SPHK2 modulates HDAC activity either by direct binding or through activation of nuclear reactive oxygen species and regulates cell cycle and pro-inflammatory gene expression. Potential implication of association of SPHK2 with the co-repressor complexes and generation of S1P in the nucleus on chromatin remodeling under normal and pathological conditions is discussed. A better understanding of sphingolipid signaling in the nucleus will facilitate the design and development of new and novel therapeutic approaches to modulate expression of pro-inflammatory and cell cycle dependent genes in human pathologies such as cancer, bacterial lung infection, neurodegeneration, and cystic fibrosis.
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Affiliation(s)
- Panfeng Fu
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois
| | - David L Ebenezer
- Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois
| | - Alison W Ha
- Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois
| | | | - Anantha Harijith
- Department of Pediatrics, University of Illinois, Chicago, Illinois
| | - Viswanathan Natarajan
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois.,Department of Medicine, University of Illinois, Chicago, Illinois
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25
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Yang Q, Sang S, Chen Y, Wei Z, Wang P. The Role of Arabidopsis Inositol Polyphosphate Kinase AtIPK2β in Glucose Suppression of Seed Germination and Seedling Development. PLANT & CELL PHYSIOLOGY 2018; 59:343-354. [PMID: 29216370 DOI: 10.1093/pcp/pcx186] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 11/19/2017] [Indexed: 06/07/2023]
Abstract
Seed germination and subsequent seedling development are critical phases in plants. These processes are regulated by a complex molecular network in which sugar has been reported to play an essential role. However, factors affecting sugar responses remain to be fully elucidated. In this study, we demonstrate that AtIPK2β, known to participate in the synthesis of myo-inositol 1,2,3,4,5,6-hexakisphosphate (IP6, phytate), affects Arabidopsis responses to glucose during seed germination. The loss-of-function mutant atipk2β showed increased sensitivity to 6% glucose and paclobutrazol (PAC). Yeast two-hybrid assay showed that AtIPK2β interacts with sucrose non-fermenting-1-related protein kinase (SnRK1.1), and bimolecular fluorescence complementation (BiFC) and pull-down assay further confirmed this interaction. Moreover, AtIPK2β was phosphorylated by SnRK1.1 in vitro, and the effect of restoring AtIPK2β to yeast cells lacking IPK2 (Δipk2) was abolished by catalytically active SnRK1.1. Further analysis indicated that IP6 reduces the suppression of seed germination caused by glucose, accompanied by altered expression levels of glucose-/hormone-responsive genes. Collectively, these findings indicate that AtIPK2β and IP6 are involved in glucose suppression of seed germination and that AtIPK2β enzyme activity is likely to be regulated by SnRK1.1.
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Affiliation(s)
- Qiaofeng Yang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Sihong Sang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yao Chen
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zhaoyun Wei
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Peng Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
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26
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Fu C, Tyagi R, Chin AC, Rojas T, Li RJ, Guha P, Bernstein IA, Rao F, Xu R, Cha JY, Xu J, Snowman AM, Semenza GL, Snyder SH. Inositol Polyphosphate Multikinase Inhibits Angiogenesis via Inositol Pentakisphosphate-Induced HIF-1α Degradation. Circ Res 2017; 122:457-472. [PMID: 29279301 DOI: 10.1161/circresaha.117.311983] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/18/2017] [Accepted: 12/22/2017] [Indexed: 12/17/2022]
Abstract
RATIONALE Inositol polyphosphate multikinase (IPMK) and its major product inositol pentakisphosphate (IP5) regulate a variety of cellular functions, but their role in vascular biology remains unexplored. OBJECTIVE We have investigated the role of IPMK in regulating angiogenesis. METHODS AND RESULTS Deletion of IPMK in fibroblasts induces angiogenesis in both in vitro and in vivo models. IPMK deletion elicits a substantial increase of VEGF (vascular endothelial growth factor), which mediates the regulation of angiogenesis by IPMK. The regulation of VEGF by IPMK requires its catalytic activity. IPMK is predominantly nuclear and regulates gene transcription. However, IPMK does not apparently serve as a transcription factor for VEGF. HIF (hypoxia-inducible factor)-1α is a major determinant of angiogenesis and induces VEGF transcription. IPMK deletion elicits a major enrichment of HIF-1α protein and thus VEGF. HIF-1α is constitutively ubiquitinated by pVHL (von Hippel-Lindau protein) followed by proteasomal degradation under normal conditions. However, HIF-1α is not recognized and ubiquitinated by pVHL in IPMK KO (knockout) cells. IP5 reinstates the interaction of HIF-1α and pVHL. HIF-1α prolyl hydroxylation, which is prerequisite for pVHL recognition, is interrupted in IPMK-deleted cells. IP5 promotes HIF-1α prolyl hydroxylation and thus pVHL-dependent degradation of HIF-1α. Deletion of IPMK in mouse brain increases HIF-1α/VEGF levels and vascularization. The increased VEGF in IPMK KO disrupts blood-brain barrier and enhances brain blood vessel permeability. CONCLUSIONS IPMK, via its product IP5, negatively regulates angiogenesis by inhibiting VEGF expression. IP5 acts by enhancing HIF-1α hydroxylation and thus pVHL-dependent degradation of HIF-1α.
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Affiliation(s)
- Chenglai Fu
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Richa Tyagi
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Alfred C Chin
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Tomas Rojas
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Ruo-Jing Li
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Prasun Guha
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Isaac A Bernstein
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Feng Rao
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Risheng Xu
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jiyoung Y Cha
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jing Xu
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Adele M Snowman
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Gregg L Semenza
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Solomon H Snyder
- From the Solomon H. Snyder Department of Neuroscience (C.F., R.T., A.C.C., T.R., P.G., I.A.B., F.R., R.X., J.Y.C., J.X., A.M.S., S.H.S.), Department of Pharmacology and Molecular Sciences (R.-J.L., S.H.S.), Institute for Cell Engineering (G.L.S.), McKusick-Nathans Institute of Genetic Medicine (G.L.S.), Department of Pediatrics (G.L.S.), Department of Medicine (G.L.S.), Department of Oncology (G.L.S.), Department of Radiation Oncology (G.L.S.), Department of Biological Chemistry (G.L.S.), and Department of Psychiatry and Behavioral Sciences (S.H.S.), Johns Hopkins University School of Medicine, Baltimore, MD.
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27
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Wickner RB, Kelly AC, Bezsonov EE, Edskes HK. [PSI+] prion propagation is controlled by inositol polyphosphates. Proc Natl Acad Sci U S A 2017; 114:E8402-E8410. [PMID: 28923943 PMCID: PMC5635934 DOI: 10.1073/pnas.1714361114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The yeast prions [PSI+] and [URE3] are folded in-register parallel β-sheet amyloids of Sup35p and Ure2p, respectively. In a screen for antiprion systems curing [PSI+] without protein overproduction, we detected Siw14p as an antiprion element. An array of genetic tests confirmed that many variants of [PSI+] arising in the absence of Siw14p are cured by restoring normal levels of the protein. Siw14p is a pyrophosphatase specifically cleaving the β phosphate from 5-diphosphoinositol pentakisphosphate (5PP-IP5), suggesting that increased levels of this or some other inositol polyphosphate favors [PSI+] propagation. In support of this notion, we found that nearly all variants of [PSI+] isolated in a WT strain were lost upon loss of ARG82, which encodes inositol polyphosphate multikinase. Inactivation of the Arg82p kinase by D131A and K133A mutations (preserving Arg82p's nonkinase transcription regulation functions) resulted the loss of its ability to support [PSI+] propagation. The loss of [PSI+] in arg82Δ is independent of Hsp104's antiprion activity. [PSI+] variants requiring Arg82p could propagate in ipk1Δ (IP5 kinase), kcs1Δ (IP6 5-kinase), vip1Δ (IP6 1-kinase), ddp1Δ (inositol pyrophosphatase), or kcs1Δ vip1Δ mutants but not in ipk1Δ kcs1Δ or ddp1Δ kcs1Δ double mutants. Thus, nearly all [PSI+] prion variants require inositol poly-/pyrophosphates for their propagation, and at least IP6 or 5PP-IP4 can support [PSI+] propagation.
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Affiliation(s)
- Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892
| | - Amy C Kelly
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892
| | - Evgeny E Bezsonov
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892
| | - Herman K Edskes
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892
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28
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Camelo C, Vilas-Boas F, Cepeda AP, Real C, Barros-Martins J, Pinto F, Soares H, Marinho HS, Cyrne L. Opi1p translocation to the nucleus is regulated by hydrogen peroxide in Saccharomyces cerevisiae. Yeast 2017; 34:383-395. [PMID: 28581036 DOI: 10.1002/yea.3240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 05/29/2017] [Accepted: 05/30/2017] [Indexed: 01/12/2023] Open
Abstract
During exposure of yeast cells to low levels of hydrogen peroxide (H2 O2 ), the expression of several genes is regulated for cells to adapt to the surrounding oxidative environment. Such adaptation involves modification of plasma membrane lipid composition, reorganization of ergosterol-rich microdomains and altered gene expression of proteins involved in lipid and vesicle traffic, to decrease permeability to exogenous H2 O2 . Opi1p is a transcriptional repressor that is inactive when present at the nuclear membrane/endoplasmic reticulum, but represseses transcription of inositol upstream activating sequence (UASINO )-containing genes, many of which are involved in the synthesis of phospholipids and fatty acids, when it is translocated to the nucleus. We investigated whether H2 O2 in concentrations inducing adaptation regulates Opi1p function. We found that, in the presence of H2 O2 , GFP-Opi1p fusion protein translocates to the nucleus and, concomitantly, the expression of UASINO -containing genes is affected. We also investigated whether cysteine residues of Opi1p were implicated in the H2 O2 -mediated translocation of this protein to the nucleus and identified cysteine residue 159 as essential for this process. Our work shows that Opi1p is redox-regulated and establishes a new mechanism of gene regulation involving Opi1p, which is important for adaptation to H2 O2 in yeast cells. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Carolina Camelo
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
| | - Filipe Vilas-Boas
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
| | - Andreia Pereira Cepeda
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
| | - Carla Real
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
| | - Joana Barros-Martins
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
| | - Francisco Pinto
- Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal.,BioISI - Biosystems and Integrative Sciences Institute, Campo Grande, Lisboa, Portugal
| | - Helena Soares
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal.,Escola Superior de Tecnologia da Saúde de Lisboa, 1990-096, Lisboa, Portugal
| | - H Susana Marinho
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal.,Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
| | - Luisa Cyrne
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal.,Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
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29
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Duong QH, Clark KD, Lapsley KG, Pegg RB. Determination of myo -inositol phosphates in tree nuts and grain fractions by HPLC–ESI–MS. J Food Compost Anal 2017. [DOI: 10.1016/j.jfca.2017.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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30
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Kim E, Beon J, Lee S, Park SJ, Ahn H, Kim MG, Park JE, Kim W, Yuk JM, Kang SJ, Lee SH, Jo EK, Seong RH, Kim S. Inositol polyphosphate multikinase promotes Toll-like receptor-induced inflammation by stabilizing TRAF6. SCIENCE ADVANCES 2017; 3:e1602296. [PMID: 28439546 PMCID: PMC5400429 DOI: 10.1126/sciadv.1602296] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 02/24/2017] [Indexed: 05/08/2023]
Abstract
Toll-like receptor (TLR) signaling is tightly controlled to protect hosts from microorganisms while simultaneously preventing uncontrolled immune responses. Tumor necrosis factor receptor-associated factor 6 (TRAF6) is a critical mediator of TLR signaling, but the precise mechanism of how TRAF6 protein stability is strictly controlled still remains obscure. We show that myeloid-specific deletion of inositol polyphosphate multikinase (IPMK), which has both inositol polyphosphate kinase activities and noncatalytic signaling functions, protects mice against polymicrobial sepsis and lipopolysaccharide-induced systemic inflammation. IPMK depletion in macrophages results in decreased levels of TRAF6 protein, thereby dampening TLR-induced signaling and proinflammatory cytokine production. Mechanistically, the regulatory role of IPMK is independent of its catalytic function, instead reflecting its direct binding to TRAF6. This interaction stabilizes TRAF6 by blocking its K48-linked ubiquitination and subsequent degradation by the proteasome. Thus, these findings identify IPMK as a key determinant of TRAF6 stability and elucidate the physiological function of IPMK in TLR-induced innate immunity.
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Affiliation(s)
- Eunha Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jiyoon Beon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Seulgi Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Seung Ju Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Hyoungjoon Ahn
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Min Gyu Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jeong Eun Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Wooseob Kim
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea
| | - Jae-Min Yuk
- Department of Infection Biology, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Suk-Jo Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Seung-Hyo Lee
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 34141, Korea
| | - Eun-Kyeong Jo
- Department of Microbiology, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Rho Hyun Seong
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea
- Corresponding author. (R.H.S.); (S.K.)
| | - Seyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
- KAIST Institute for the BioCentury, KAIST, Daejeon 34141, Korea
- Corresponding author. (R.H.S.); (S.K.)
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31
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Duong QH, Clark KD, Lapsley KG, Pegg RB. Quantification of inositol phosphates in almond meal and almond brown skins by HPLC/ESI/MS. Food Chem 2017; 229:84-92. [PMID: 28372252 DOI: 10.1016/j.foodchem.2017.02.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 01/26/2017] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
Abstract
The extraction and measurement of all six forms of inositol phosphates (InsPs) in almond meal and brown skins were improved from existing methods by pH adjustment, supplementation of EDTA, and rapid analysis via anion-exchange high-performance liquid chromatography coupled with electrospray ionization mass spectrometry. The quantity of InsPs in six major almond cultivars ranged from 8 to 12μmol/g in the meal and 5 to 14μmol/g in the brown skins. InsP6 was the dominant form, but lower forms still accounted for ∼20% of the total InsPs molar concentration in a majority of the samples. InsPs contributed 32-55% of the organic phosphorus content and 20-38% of the total phosphorus content in the meal. In brown skins, these ranges were 44-77% and 30-52%, respectively. The successful application of this analytical method with almonds demonstrates its potential use for re-examination of the reported phytic acid contents in many other tree nuts, legumes, grains, and complex foods.
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Affiliation(s)
- Quynh H Duong
- Department of Food Science & Technology, College of Agricultural and Environmental Sciences, The University of Georgia, 100 Cedar Street, Athens, GA 30602, USA
| | - Kevin D Clark
- Department of Food Science & Technology, College of Agricultural and Environmental Sciences, The University of Georgia, 100 Cedar Street, Athens, GA 30602, USA
| | - Karen G Lapsley
- Almond Board of California, 1150 Ninth Street, Suite, 1500, Modesto, CA 95354, USA
| | - Ronald B Pegg
- Department of Food Science & Technology, College of Agricultural and Environmental Sciences, The University of Georgia, 100 Cedar Street, Athens, GA 30602, USA.
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Phosphoinositides in the nucleus and myogenic differentiation: how a nuclear turtle with a PHD builds muscle. Biochem Soc Trans 2016; 44:299-306. [PMID: 26862219 DOI: 10.1042/bst20150238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Phosphoinositides are a family of phospholipid messenger molecules that control various aspects of cell biology in part by interacting with and regulating downstream protein partners. Importantly, phosphoinositides are present in the nucleus. They form part of the nuclear envelope and are present within the nucleus in nuclear speckles, intra nuclear chromatin domains, the nuclear matrix and in chromatin. What their exact role is within these compartments is not completely clear, but the identification of nuclear specific proteins that contain phosphoinositide interaction domains suggest that they are important regulators of DNA topology, chromatin conformation and RNA maturation and export. The plant homeo domain (PHD) finger is a phosphoinositide binding motif that is largely present in nuclear proteins that regulate chromatin conformation. In the present study I outline how changes in the levels of the nuclear phosphoinositide PtdIns5P impact on muscle cell differentiation through the PHD finger of TAF3 (TAF, TATA box binding protein (TBP)-associated factor), which is a core component of a number of different basal transcription complexes.
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Lu HP, Pang WQ, Li WX, Tan YY, Wang Q, Zhao HJ, Shu QY. Tissue-specific expression, developmentally and spatially regulated alternative splicing, and protein subcellular localization of OsLpa rice. J Zhejiang Univ Sci B 2016; 17:100-9. [PMID: 26834011 DOI: 10.1631/jzus.b1500205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The OsLpa1 gene (LOC_Os57400) was identified to be involved in phytic acid (PA) metabolism because its knockout and missense mutants reduce PA content in rice grain. However, little is known about the molecular characteristics of OsLpa rice and of its homologues in other plants. In the present study, the spatial pattern of OsLpa1 expression was revealed using OsLpa1 promoter::GUS transgenic plants (GUS: β-glucuronidase); GUS histochemical assay showed that OsLpa1 was strongly expressed in stem, leaf, and root tissues, but in floral organ it is expressed mainly and strongly in filaments. In seeds, GUS staining was concentrated in the aleurone layers; a few blue spots were observed in the outer layers of embryo, but no staining was observed in the endosperm. Three OsLpa1 transcripts (OsLpa1.1, OsLpa1.2, OsLpa1.3) are produced due to alternative splicing; quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis revealed that the abundance of OsLpa1.3 was negligible compared with OsLpa1.1 and OsLpa all tissues. OsLpa1.2 is predominant in germinating seeds (about 5 times that of OsLpa1.1), but its abundance decreases quickly with the development of seedlings and plants, whereas the abundance of OsLpa1.1 rises and falls, reaching its highest level in 45-d-old plants, with abundance greater than that of OsLpa both leaves and roots. In seeds, the abundance of OsLpa1 continuously increases with seed growth, being 27.5 and 15 times greater in 28-DAF (day after flowering) seeds than in 7-DAF seeds for OsLpa1.1 and OsLpa1.2, respectively. Transient expression of chimeric genes with green fluorescence protein (GFP) in rice protoplasts demonstrated that all proteins encoded by the three OsLpa1 transcripts are localized to the chloroplast.
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Affiliation(s)
- Hai-ping Lu
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou 310029, China
| | - Wei-qin Pang
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou 310029, China
| | - Wen-xu Li
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou 310029, China
| | - Yuan-yuan Tan
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou 310029, China
| | - Qing Wang
- Wuxi Hupper Bioseed Technology Academy Ltd., Wuxi 214000, China
| | - Hai-jun Zhao
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou 310029, China
| | - Qing-yao Shu
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou 310029, China
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Inositol polyphosphates intersect with signaling and metabolic networks via two distinct mechanisms. Proc Natl Acad Sci U S A 2016; 113:E6757-E6765. [PMID: 27791083 DOI: 10.1073/pnas.1606853113] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Inositol-based signaling molecules are central eukaryotic messengers and include the highly phosphorylated, diffusible inositol polyphosphates (InsPs) and inositol pyrophosphates (PP-InsPs). Despite the essential cellular regulatory functions of InsPs and PP-InsPs (including telomere maintenance, phosphate sensing, cell migration, and insulin secretion), the majority of their protein targets remain unknown. Here, the development of InsP and PP-InsP affinity reagents is described to comprehensively annotate the interactome of these messenger molecules. By using the reagents as bait, >150 putative protein targets were discovered from a eukaryotic cell lysate (Saccharomyces cerevisiae). Gene Ontology analysis of the binding partners revealed a significant overrepresentation of proteins involved in nucleotide metabolism, glucose metabolism, ribosome biogenesis, and phosphorylation-based signal transduction pathways. Notably, we isolated and characterized additional substrates of protein pyrophosphorylation, a unique posttranslational modification mediated by the PP-InsPs. Our findings not only demonstrate that the PP-InsPs provide a central line of communication between signaling and metabolic networks, but also highlight the unusual ability of these molecules to access two distinct modes of action.
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35
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Ye W, Ren W, Kong L, Zhang W, Wang T. Transcriptomic Profiling Analysis of Arabidopsis thaliana Treated with Exogenous Myo-Inositol. PLoS One 2016; 11:e0161949. [PMID: 27603208 PMCID: PMC5014391 DOI: 10.1371/journal.pone.0161949] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/15/2016] [Indexed: 11/26/2022] Open
Abstract
Myo-insositol (MI) is a crucial substance in the growth and developmental processes in plants. It is commonly added to the culture medium to promote adventitious shoot development. In our previous work, MI was found in influencing Agrobacterium-mediated transformation. In this report, a high-throughput RNA sequencing technique (RNA-Seq) was used to investigate differently expressed genes in one-month-old Arabidopsis seedling grown on MI free or MI supplemented culture medium. The results showed that 21,288 and 21,299 genes were detected with and without MI treatment, respectively. The detected genes included 184 new genes that were not annotated in the Arabidopsis thaliana reference genome. Additionally, 183 differentially expressed genes were identified (DEGs, FDR ≤0.05, log2 FC≥1), including 93 up-regulated genes and 90 down-regulated genes. The DEGs were involved in multiple pathways, such as cell wall biosynthesis, biotic and abiotic stress response, chromosome modification, and substrate transportation. Some significantly differently expressed genes provided us with valuable information for exploring the functions of exogenous MI. RNA-Seq results showed that exogenous MI could alter gene expression and signaling transduction in plant cells. These results provided a systematic understanding of the functions of exogenous MI in detail and provided a foundation for future studies.
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Affiliation(s)
- Wenxing Ye
- Department of Grassland Science, China Agricultural University, Haidian District, Beijing, PR China
- Beijing Key Laboratory of Grassland Science, China Agricultural University, Haidian District, Beijing, PR China
| | - Weibo Ren
- Institute of Grassland Research of Chinese Academy of Agricultural Science, Saihan District, Hohhot, Inner Mongolia, PR China
| | - Lingqi Kong
- Institute of Grassland Research of Chinese Academy of Agricultural Science, Saihan District, Hohhot, Inner Mongolia, PR China
| | - Wanjun Zhang
- Department of Grassland Science, China Agricultural University, Haidian District, Beijing, PR China
- Beijing Key Laboratory of Grassland Science, China Agricultural University, Haidian District, Beijing, PR China
| | - Tao Wang
- State Key Laboratory of Agro-biotechnology, China Agricultural University, Haidian District, Beijing, PR China
- Beijing Key Laboratory of Grassland Science, China Agricultural University, Haidian District, Beijing, PR China
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36
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Hager A, Wu M, Wang H, Brown NW, Shears SB, Veiga N, Fiedler D. Cellular Cations Control Conformational Switching of Inositol Pyrophosphate Analogues. Chemistry 2016; 22:12406-14. [PMID: 27460418 PMCID: PMC5076471 DOI: 10.1002/chem.201601754] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Indexed: 12/21/2022]
Abstract
The inositol pyrophosphate messengers (PP-InsPs) are emerging as an important class of cellular regulators. These molecules have been linked to numerous biological processes, including insulin secretion and cancer cell migration, but how they trigger such a wide range of cellular responses has remained unanswered in many cases. Here, we show that the PP-InsPs exhibit complex speciation behaviour and propose that a unique conformational switching mechanism could contribute to their multifunctional effects. We synthesised non-hydrolysable bisphosphonate analogues and crystallised the analogues in complex with mammalian PPIP5K2 kinase. Subsequently, the bisphosphonate analogues were used to investigate the protonation sequence, metal-coordination properties, and conformation in solution. Remarkably, the presence of potassium and magnesium ions enabled the analogues to adopt two different conformations near physiological pH. Understanding how the intrinsic chemical properties of the PP-InsPs can contribute to their complex signalling outputs will be essential to elucidate their regulatory functions.
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Affiliation(s)
- Anastasia Hager
- Department of Chemistry, Princeton University, Washington Rd., Princeton, New Jersey, 08544, USA
| | - Mingxuan Wu
- Department of Chemistry, Princeton University, Washington Rd., Princeton, New Jersey, 08544, USA
| | - Huanchen Wang
- Inositol Signaling Group, National Institutes of Health, Research Triangle Park, North Carolina, 27709, USA
| | - Nathaniel W Brown
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle Strasse 10, 13125, Berlin, Germany
- Department of Chemistry, Princeton University, Washington Rd., Princeton, New Jersey, 08544, USA
| | - Stephen B Shears
- Inositol Signaling Group, National Institutes of Health, Research Triangle Park, North Carolina, 27709, USA
| | - Nicolás Veiga
- Cátedra de Química Inorgánica, Departamento Estrella Campos, Facultad de Química, Universidad de la República, CC 1157, Montevideo, Uruguay.
| | - Dorothea Fiedler
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle Strasse 10, 13125, Berlin, Germany.
- Department of Chemistry, Princeton University, Washington Rd., Princeton, New Jersey, 08544, USA.
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37
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Tribble EK, Ivanova PT, Grabon A, Alb JG, Faenza I, Cocco L, Brown HA, Bankaitis VA. Quantitative profiling of the endonuclear glycerophospholipidome of murine embryonic fibroblasts. J Lipid Res 2016; 57:1492-506. [PMID: 27256690 DOI: 10.1194/jlr.m068734] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Indexed: 01/18/2023] Open
Abstract
A reliable method for purifying envelope-stripped nuclei from immortalized murine embryonic fibroblasts (iMEFs) was established. Quantitative profiling of the glycerophospholipids (GPLs) in envelope-free iMEF nuclei yields several conclusions. First, we find the endonuclear glycerophospholipidome differs from that of bulk membranes, and phosphatidylcholine (PtdCho) and phosphatidylethanolamine species are the most abundant endonuclear GPLs by mass. By contrast, phosphatidylinositol (PtdIns) represents a minor species. We also find only a slight enrichment of saturated versus unsaturated GPL species in iMEF endonuclear fractions. Moreover, much lower values for GPL mass were measured in the iMEF nuclear matrix than those reported for envelope-stripped IMF-32 nuclei. The collective results indicate that the nuclear matrix in these cells is a GPL-poor environment where GPL occupies only approximately 0.1% of the total nuclear matrix volume. This value suggests GPL accommodation in this compartment can be satisfied by binding to resident proteins. Finally, we find no significant role for the PtdIns/PtdCho-transfer protein, PITPα, in shuttling PtdIns into the iMEF nuclear matrix.
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Affiliation(s)
- Emily K Tribble
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Pavlina T Ivanova
- Departments of Pharmacology and Biochemistry, Vanderbilt University School of Medicine, Vanderbilt Institute of Chemical Biology, Nashville, TN
| | - Aby Grabon
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX
| | - James G Alb
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Irene Faenza
- Cellular Signaling Laboratory, Department of Biomedical Sciences, University of Bologna, Bologna, Italy
| | - Lucio Cocco
- Cellular Signaling Laboratory, Department of Biomedical Sciences, University of Bologna, Bologna, Italy
| | - H Alex Brown
- Departments of Pharmacology and Biochemistry, Vanderbilt University School of Medicine, Vanderbilt Institute of Chemical Biology, Nashville, TN
| | - Vytas A Bankaitis
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX
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38
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Pautasso C, Reca S, Chatfield-Reed K, Chua G, Galello F, Portela P, Zaremberg V, Rossi S. Identification of novel transcriptional regulators of PKA subunits inSaccharomyces cerevisiaeby quantitative promoter–reporter screening. FEMS Yeast Res 2016; 16:fow046. [DOI: 10.1093/femsyr/fow046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2016] [Indexed: 01/22/2023] Open
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39
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Ouyang Z, Zheng G, Tomchick DR, Luo X, Yu H. Structural Basis and IP6 Requirement for Pds5-Dependent Cohesin Dynamics. Mol Cell 2016; 62:248-259. [PMID: 26971492 PMCID: PMC5560056 DOI: 10.1016/j.molcel.2016.02.033] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/25/2016] [Accepted: 02/26/2016] [Indexed: 11/24/2022]
Abstract
The ring-shaped cohesin complex regulates transcription, DNA repair, and chromosome segregation by dynamically entrapping chromosomes to promote chromosome compaction and sister-chromatid cohesion. The cohesin ring needs to open and close to allow its loading to and release from chromosomes. Cohesin dynamics are controlled by the releasing factors Pds5 and Wapl and the cohesin stabilizer Sororin. Here, we report the crystal structure of human Pds5B bound to a conserved peptide motif found in both Wapl and Sororin. Our structure establishes the basis for how Wapl and Sororin antagonistically influence cohesin dynamics. The structure further reveals that Pds5 can bind inositol hexakisphosphate (IP6). The IP6-binding segment of Pds5B is shaped like the jaw of a plier lever and inhibits the binding of Scc1 to Smc3. We propose that Pds5 stabilizes a transient, open state of cohesin to promote its release from chromosomes.
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Affiliation(s)
- Zhuqing Ouyang
- Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA
| | - Ge Zheng
- Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA
| | - Diana R Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA
| | - Xuelian Luo
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA
| | - Hongtao Yu
- Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA.
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40
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Pavlovic I, Thakor DT, Vargas JR, McKinlay CJ, Hauke S, Anstaett P, Camuña RC, Bigler L, Gasser G, Schultz C, Wender PA, Jessen HJ. Cellular delivery and photochemical release of a caged inositol-pyrophosphate induces PH-domain translocation in cellulo. Nat Commun 2016; 7:10622. [PMID: 26842801 PMCID: PMC4743007 DOI: 10.1038/ncomms10622] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/05/2016] [Indexed: 02/07/2023] Open
Abstract
Inositol pyrophosphates, such as diphospho-myo-inositol pentakisphosphates (InsP7), are an important family of signalling molecules, implicated in many cellular processes and therapeutic indications including insulin secretion, glucose homeostasis and weight gain. To understand their cellular functions, chemical tools such as photocaged analogues for their real-time modulation in cells are required. Here we describe a concise, modular synthesis of InsP7 and caged InsP7. The caged molecule is stable and releases InsP7 only on irradiation. While photocaged InsP7 does not enter cells, its cellular uptake is achieved using nanoparticles formed by association with a guanidinium-rich molecular transporter. This novel synthesis and unprecedented polyphosphate delivery strategy enable the first studies required to understand InsP7 signalling in cells with controlled spatiotemporal resolution. It is shown herein that cytoplasmic photouncaging of InsP7 leads to translocation of the PH-domain of Akt, an important signalling-node kinase involved in glucose homeostasis, from the membrane into the cytoplasm. Photocaged inositol-pyrophosphates offer a tool to study cellular signalling, but their challenging synthesis has precluded any biological studies so far. Here, the authors report the synthesis and cellular delivery of a photocaged analogue, and show that it mediates protein translocation in cellulo.
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Affiliation(s)
- Igor Pavlovic
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Divyeshsinh T Thakor
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Jessica R Vargas
- Departments of Chemistry and Chemical and Systems Biology, Stanford University, Stanford, California 94305, USA
| | - Colin J McKinlay
- Departments of Chemistry and Chemical and Systems Biology, Stanford University, Stanford, California 94305, USA
| | - Sebastian Hauke
- European Molecular Biology Laboratory (EMBL), Cell Biology &Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Philipp Anstaett
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Rafael C Camuña
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Málaga, Malaga 29071, Spain
| | - Laurent Bigler
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Gilles Gasser
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology &Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Paul A Wender
- Departments of Chemistry and Chemical and Systems Biology, Stanford University, Stanford, California 94305, USA
| | - Henning J Jessen
- Department of Chemistry and Pharmacy, Albert-Ludwigs University Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
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41
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Pavlovic I, Thakor DT, Jessen HJ. Synthesis of 2-diphospho-myo-inositol 1,3,4,5,6-pentakisphosphate and a photocaged analogue. Org Biomol Chem 2016; 14:5559-62. [DOI: 10.1039/c6ob00094k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diphosphoinositol polyphosphates (inositol pyrophosphates, X-InsP7) are a family of second messengers with important roles in eukaryotic biology. A new approach targeting 2-InsP7 and a photocaged analogue is described.
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Affiliation(s)
- I. Pavlovic
- Department of Chemistry
- University of Zürich
- 8057 Zürich
- Switzerland
| | - D. T. Thakor
- Department of Chemistry
- University of Zürich
- 8057 Zürich
- Switzerland
| | - H. J. Jessen
- Department of Chemistry and Pharmacy
- Albert-Ludwigs University Freiburg
- 79104 Freiburg
- Germany
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42
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Sparvoli F, Cominelli E. Seed Biofortification and Phytic Acid Reduction: A Conflict of Interest for the Plant? PLANTS 2015; 4:728-55. [PMID: 27135349 PMCID: PMC4844270 DOI: 10.3390/plants4040728] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/13/2015] [Indexed: 02/03/2023]
Abstract
Most of the phosphorus in seeds is accumulated in the form of phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate, InsP6). This molecule is a strong chelator of cations important for nutrition, such as iron, zinc, magnesium, and calcium. For this reason, InsP6 is considered an antinutritional factor. In recent years, efforts to biofortify seeds through the generation of low phytic acid (lpa) mutants have been noteworthy. Moreover, genes involved in the biosynthesis and accumulation of this molecule have been isolated and characterized in different species. Beyond its role in phosphorus storage, phytic acid is a very important signaling molecule involved in different regulatory processes during plant development and responses to different stimuli. Consequently, many lpa mutants show different negative pleitotropic effects. The strength of these pleiotropic effects depends on the specific mutated gene, possible functional redundancy, the nature of the mutation, and the spatio-temporal expression of the gene. Breeding programs or transgenic approaches aimed at development of new lpa mutants must take into consideration these different aspects in order to maximize the utility of these mutants.
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Affiliation(s)
- Francesca Sparvoli
- Institute of Agricultural Biology and Biotechnology, CNR, Via Bassini 15, 20133 Milan, Italy.
| | - Eleonora Cominelli
- Institute of Agricultural Biology and Biotechnology, CNR, Via Bassini 15, 20133 Milan, Italy.
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43
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Jiao C, Summerlin M, Bruzik KS, Hanakahi L. Synthesis of Biotinylated Inositol Hexakisphosphate To Study DNA Double-Strand Break Repair and Affinity Capture of IP6-Binding Proteins. Biochemistry 2015; 54:6312-22. [PMID: 26397942 DOI: 10.1021/acs.biochem.5b00642] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inositol hexakisphosphate (IP6) is a soluble inositol polyphosphate, which is abundant in mammalian cells. Despite the participation of IP6 in critical cellular functions, few IP6-binding proteins have been characterized. We report on the synthesis, characterization, and application of biotin-labeled IP6 (IP6-biotin), which has biotin attached at position 2 of the myo-inositol ring via an aminohexyl linker. Like natural IP6, IP6-biotin stimulated DNA ligation by nonhomologous end joining (NHEJ) in vitro. The Ku protein is a required NHEJ factor that has been shown to bind IP6. We found that IP6-biotin could affinity capture Ku and other required NHEJ factors from human cell extracts, including the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), XRCC4, and XLF. Direct binding studies with recombinant proteins show that Ku is the only NHEJ factor with affinity for IP6-biotin. DNA-PKcs, XLF, and the XRCC4:ligase IV complex interact with Ku in cell extracts and likely interact indirectly with IP6-biotin. IP6-biotin was used to tether streptavidin to Ku, which inhibited NHEJ in vitro. These proof-of-concept experiments suggest that molecules like IP6-biotin might be used to molecularly target biologically important proteins that bind IP6. IP6-biotin affinity capture experiments show that numerous proteins specifically bind IP6-biotin, including casein kinase 2, which is known to bind IP6, and nucleolin. Protein binding to IP6-biotin is selective, as IP3, IP4, and IP5 did not compete for binding of proteins to IP6-biotin. Our results document IP6-biotin as a useful tool for investigating the role of IP6 in biological systems.
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Affiliation(s)
- Chensong Jiao
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago , 833 South Wood Street (M/C 781), Chicago, Illinois 60612, United States
| | - Matthew Summerlin
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago , Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, Illinois 61107, United States
| | - Karol S Bruzik
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago , 833 South Wood Street (M/C 781), Chicago, Illinois 60612, United States
| | - Leslyn Hanakahi
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago , Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, Illinois 61107, United States
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44
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Lowry J, Yochem J, Chuang CH, Sugioka K, Connolly AA, Bowerman B. High-Throughput Cloning of Temperature-Sensitive Caenorhabditis elegans Mutants with Adult Syncytial Germline Membrane Architecture Defects. G3 (BETHESDA, MD.) 2015; 5:2241-55. [PMID: 26311651 PMCID: PMC4632044 DOI: 10.1534/g3.115.021451] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022]
Abstract
The adult Caenorhabditis elegans hermaphrodite gonad consists of two mirror-symmetric U-shaped arms, with germline nuclei located peripherally in the distal regions of each arm. The nuclei are housed within membrane cubicles that are open to the center, forming a syncytium with a shared cytoplasmic core called the rachis. As the distal germline nuclei progress through meiotic prophase, they move proximally and eventually cellularize as their compartments grow in size. The development and maintenance of this complex and dynamic germline membrane architecture are relatively unexplored, and we have used a forward genetic screen to identify 20 temperature-sensitive mutations in 19 essential genes that cause defects in the germline membrane architecture. Using a combined genome-wide SNP mapping and whole genome sequencing strategy, we have identified the causal mutations in 10 of these mutants. Four of the genes we have identified are conserved, with orthologs known to be involved in membrane biology, and are required for proper development or maintenance of the adult germline membrane architecture. This work provides a starting point for further investigation of the mechanisms that control the dynamics of syncytial membrane architecture during adult oogenesis.
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Affiliation(s)
- Josh Lowry
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - John Yochem
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Chien-Hui Chuang
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Kenji Sugioka
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Amy A Connolly
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
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Marriott AS, Copeland NA, Cunningham R, Wilkinson MC, McLennan AG, Jones NJ. Diadenosine 5', 5'''-P(1),P(4)-tetraphosphate (Ap4A) is synthesized in response to DNA damage and inhibits the initiation of DNA replication. DNA Repair (Amst) 2015. [PMID: 26204256 DOI: 10.1016/j.dnarep.2015.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The level of intracellular diadenosine 5', 5'''-P(1),P(4)-tetraphosphate (Ap4A) increases several fold in mammalian cells treated with non-cytotoxic doses of interstrand DNA-crosslinking agents such as mitomycin C. It is also increased in cells lacking DNA repair proteins including XRCC1, PARP1, APTX and FANCG, while >50-fold increases (up to around 25 μM) are achieved in repair mutants exposed to mitomycin C. Part of this induced Ap4A is converted into novel derivatives, identified as mono- and di-ADP-ribosylated Ap4A. Gene knockout experiments suggest that DNA ligase III is primarily responsible for the synthesis of damage-induced Ap4A and that PARP1 and PARP2 can both catalyze its ADP-ribosylation. Degradative proteins such as aprataxin may also contribute to the increase. Using a cell-free replication system, Ap4A was found to cause a marked inhibition of the initiation of DNA replicons, while elongation was unaffected. Maximum inhibition of 70-80% was achieved with 20 μM Ap4A. Ap3A, Ap5A, Gp4G and ADP-ribosylated Ap4A were without effect. It is proposed that Ap4A acts as an important inducible ligand in the DNA damage response to prevent the replication of damaged DNA.
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Affiliation(s)
- Andrew S Marriott
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Nikki A Copeland
- Division of Biomedical and Life Sciences, University of Lancaster, Lancaster LA1 4YG, UK
| | - Ryan Cunningham
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Mark C Wilkinson
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Alexander G McLennan
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
| | - Nigel J Jones
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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Sec14-like phosphatidylinositol-transfer proteins and diversification of phosphoinositide signalling outcomes. Biochem Soc Trans 2015; 42:1383-8. [PMID: 25233419 DOI: 10.1042/bst20140187] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The physiological functions of phosphatidylinositol (PtdIns)-transfer proteins (PITPs)/phosphatidylcholine (PtdCho)-transfer proteins are poorly characterized, even though these proteins are conserved throughout the eukaryotic kingdom. Much of the progress in elucidating PITP functions has come from exploitation of genetically tractable model organisms, but the mechanisms for how PITPs execute their biological activities remain unclear. Structural and molecular dynamics approaches are filling in the details for how these proteins actually work as molecules. In the present paper, we discuss our recent work with Sec14-like PITPs and describe how PITPs integrate diverse territories of the lipid metabolome with phosphoinositide signalling.
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47
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Phillippy BQ, Perera IY, Donahue JL, Gillaspy GE. Certain Malvaceae Plants Have a Unique Accumulation of myo-Inositol 1,2,4,5,6-Pentakisphosphate. PLANTS (BASEL, SWITZERLAND) 2015; 4:267-83. [PMID: 27135328 PMCID: PMC4844327 DOI: 10.3390/plants4020267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/19/2015] [Indexed: 01/28/2023]
Abstract
Methods used to quantify inositol phosphates in seeds lack the sensitivity and specificity necessary to accurately detect the lower concentrations of these compounds contained in the leaves of many plants. In order to measure inositol hexakisphosphate (InsP₆) and inositol pentakisphosphate (InsP₅) levels in leaves of different plants, a method was developed to concentrate and pre-purify these compounds prior to analysis. Inositol phosphates were extracted from leaves with diluted HCl and concentrated on small anion exchange columns. Reversed-phase solid phase extraction cartridges were used to remove compounds that give peaks that sometimes interfere during HPLC. The method permitted the determination of InsP₆ and InsP₅ concentrations in leaves as low as 10 µM and 2 µM, respectively. Most plants analyzed contained a high ratio of InsP₆ to InsP₅. In contrast, certain members of the Malvaceae family, such as cotton (Gossypium) and some hibiscus (Hibiscus) species, had a preponderance of InsP₅. Radiolabeling of cotton seedlings also showed increased amounts of InsP₅ relative to InsP₆. Why some Malvaceae species exhibit a reversal of the typical ratios of these inositol phosphates is an intriguing question for future research.
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Affiliation(s)
- Brian Q Phillippy
- Plant and Microbial Biology, Campus Box 7612, North Carolina State University, Raleigh, NC 27695, USA.
| | - Imara Y Perera
- Plant and Microbial Biology, Campus Box 7612, North Carolina State University, Raleigh, NC 27695, USA.
| | - Janet L Donahue
- Biochemistry, Virginia Polytechnic and State University, Blacksburg, VA 24061, USA.
| | - Glenda E Gillaspy
- Biochemistry, Virginia Polytechnic and State University, Blacksburg, VA 24061, USA.
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Koenig S, Moreau C, Dupont G, Scoumanne A, Erneux C. Regulation of NGF-driven neurite outgrowth by Ins(1,4,5)P3 kinase is specifically associated with the two isoenzymes Itpka and Itpkb in a model of PC12 cells. FEBS J 2015; 282:2553-69. [PMID: 25892505 DOI: 10.1111/febs.13300] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/10/2015] [Accepted: 04/15/2015] [Indexed: 11/26/2022]
Abstract
Four inositol phosphate kinases catalyze phosphorylation of the second messenger inositol 1,4,5-trisphosphate [Ins(1,4,5)P3 ] to inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4 ]: these enzymes comprise three isoenzymes of inositol 1,4,5-trisphosphate 3-kinase (Itpk), referred to as Itpka, Itpkb and Itpkc, and the inositol polyphosphate multikinase (IPMK). The four enzymes that act on Ins(1,4,5)P3 are all expressed in rat pheochromocytoma PC12 cells, a model that is used to study neurite outgrowth induced by nerve growth factor (NGF). We compared the effect of over-expression of the four GFP-tagged kinases on NGF-induced neurite outgrowth. Our data show that over-expression of the Itpka and Itpkb isoforms inhibits NGF-induced neurite outgrowth, but over-expression of Itpkc and IPMK does not. Surprisingly, over-expression of the N-terminal F-actin binding domain of Itpka, which lacks catalytic activity, was as effective at inhibiting neurite outgrowth as the full-length enzyme. Neurite length was also significantly decreased in cells over-expressing Itpka and Itpkb but not Itpkc or IPMK. This result did not depend on the over-expression level of any of the kinases. PC12 cells over-expressing GFP-tagged kinase-dead mutants Itpka/b have shorter neurites than GFP control cells. The decrease in neurite length was never as pronounced as observed with wild-type GFP-tagged Itpka/b. Finally, the percentage of neurite-bearing cells was increased in cells over-expressing the membranous type I Ins(1,4,5)P3 5-phosphatase. We conclude that Itpka and Itpkb inhibit neurite outgrowth through both F-actin binding and localized Ins(1,4,5)P3 3-kinase activity. Itpkc and IPMK do not influence neurite outgrowth or neurite length in this model.
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Affiliation(s)
- Sandra Koenig
- Interdisciplinary Research Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Colette Moreau
- Interdisciplinary Research Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Geneviève Dupont
- Unité de Chronobiologie Théorique, Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium
| | - Ariane Scoumanne
- Laboratory of Functional Genetics, GIGA Signal Transduction, Université de Liège, Liège, Belgium
| | - Christophe Erneux
- Interdisciplinary Research Institute, Université Libre de Bruxelles, Brussels, Belgium
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Inositol pyrophosphates regulate RNA polymerase I-mediated rRNA transcription in Saccharomyces cerevisiae. Biochem J 2015; 466:105-14. [PMID: 25423617 PMCID: PMC4325516 DOI: 10.1042/bj20140798] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ribosome biogenesis is an essential cellular process regulated by the metabolic state of a cell. We examined whether inositol pyrophosphates, energy-rich derivatives of inositol that act as metabolic messengers, play a role in ribosome synthesis in the budding yeast, Saccharomyces cerevisiae. Yeast strains lacking the inositol hexakisphosphate (IP6) kinase Kcs1, which is required for the synthesis of inositol pyrophosphates, display increased sensitivity to translation inhibitors and decreased protein synthesis. These phenotypes are reversed on expression of enzymatically active Kcs1, but not on expression of the inactive form. The kcs1Δ yeast cells exhibit reduced levels of ribosome subunits, suggesting that they are defective in ribosome biogenesis. The rate of rRNA synthesis, the first step of ribosome biogenesis, is decreased in kcs1Δ yeast strains, suggesting that RNA polymerase I (Pol I) activity may be reduced in these cells. We determined that the Pol I subunits, A190, A43 and A34.5, can accept a β-phosphate moiety from inositol pyrophosphates to undergo serine pyrophosphorylation. Although there is impaired rRNA synthesis in kcs1Δ yeast cells, we did not find any defect in recruitment of Pol I on rDNA, but observed that the rate of transcription elongation was compromised. Taken together, our findings highlight inositol pyrophosphates as novel regulators of rRNA transcription. Inositol pyrophosphates are phosphate-rich metabolic messengers that regulate many cellular processes. We observed that RNA polymerase I is pyrophosphorylated by inositol pyrophosphates, and its transcription elongation activity was reduced in budding yeast strains devoid of inositol pyrophosphates.
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50
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Fiume R, Stijf-Bultsma Y, Shah ZH, Keune WJ, Jones DR, Jude JG, Divecha N. PIP4K and the role of nuclear phosphoinositides in tumour suppression. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:898-910. [PMID: 25728392 DOI: 10.1016/j.bbalip.2015.02.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 02/03/2015] [Accepted: 02/17/2015] [Indexed: 12/27/2022]
Abstract
Phosphatidylinositol-5-phosphate (PtdIns5P)-4-kinases (PIP4Ks) are stress-regulated lipid kinases that phosphorylate PtdIns5P to generate PtdIns(4,5)P₂. There are three isoforms of PIP4Ks: PIP4K2A, 2B and 2C, which localise to different subcellular compartments with the PIP4K2B isoform being localised predominantly in the nucleus. Suppression of PIP4K expression selectively prevents tumour cell growth in vitro and prevents tumour development in mice that have lost the tumour suppressor p53. p53 is lost or mutated in over 70% of all human tumours. These studies suggest that inhibition of PIP4K signalling constitutes a novel anti-cancer therapeutic target. In this review we will discuss the role of PIP4K in tumour suppression and speculate on how PIP4K modulates nuclear phosphoinositides (PPIns) and how this might impact on nuclear functions to regulate cell growth. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Roberta Fiume
- Cellular Signalling Laboratory, DIBINEM, University of Bologna, Bologna, Italy.
| | - Yvette Stijf-Bultsma
- Inositide Laboratory, Centre for Biological Sciences, Faculty of Natural & Environmental Sciences, Life Sciences Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Zahid H Shah
- Inositide Laboratory, Centre for Biological Sciences, Faculty of Natural & Environmental Sciences, Life Sciences Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Willem Jan Keune
- The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
| | - David R Jones
- Oncology iMED, AstraZeneca, Alderley Park, Macclesfield SK10 4TF, UK
| | - Julian Georg Jude
- IMP - Institute of Molecular Pathology, Vienna Biocenter, Dr. Bohr-Gasse 7, 1030 Vienna, Austria
| | - Nullin Divecha
- Inositide Laboratory, Centre for Biological Sciences, Faculty of Natural & Environmental Sciences, Life Sciences Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
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