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Pitman MR, Davies LT, Pitson SM. An Improved Isoform-Selective Assay for Sphingosine Kinase 1 Activity. Methods Mol Biol 2017; 1697:9-20. [PMID: 28540558 DOI: 10.1007/7651_2017_41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Sphingosine kinases (SK) are the sole enzymes responsible for the production of sphingosine 1-phosphate (S1P). S1P is a signaling molecule with a plethora of targets, acting as both a second messenger intracellularly and extracellularly via a family of cell surface G-protein-coupled S1P receptors. The two sphingosine kinases, SK1 and SK2, arise from different genes and have some distinct and overlapping cellular functions that are regulated in part by differential cellular localization, developmental expression, and catalytic properties. Here, we describe an improved method for selectively detecting SK1 activity in vitro and cell lysates via the use of the zwitterionic detergent CHAPS, which effectively inhibits SK2 activity and thus allows selective analysis of SK1 activity in a range of cell samples. The assay measures the production of 32P-labeled S1P following the addition of exogenous sphingosine and [γ32P]ATP. The S1P product can be purified by Bligh-Dyer solvent extraction, separated by thin layer chromatography (TLC), and the radiolabeled S1P quantified by exposing the TLC plate to a storage phosphor screen. This sensitive, reproducible assay can be used to selectively detect SK1 activity in tissue, cell, and recombinant protein samples.
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Affiliation(s)
- Melissa R Pitman
- Molecular Signalling Laboratory, Centre for Cancer Biology, University of South Australia and SA Pathology, Frome Road, Adelaide, SA, 5000, Australia
| | - Lorena T Davies
- Molecular Signalling Laboratory, Centre for Cancer Biology, University of South Australia and SA Pathology, Frome Road, Adelaide, SA, 5000, Australia
| | - Stuart M Pitson
- Molecular Signalling Laboratory, Centre for Cancer Biology, University of South Australia and SA Pathology, Frome Road, Adelaide, SA, 5000, Australia.
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Cross M, Rajan S, Chekaiban J, Saunders J, Hamilton C, Kim JS, Coster MJ, Gasser RB, Hofmann A. Enzyme characteristics of pathogen-specific trehalose-6-phosphate phosphatases. Sci Rep 2017; 7:2015. [PMID: 28515463 PMCID: PMC5435700 DOI: 10.1038/s41598-017-02220-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/07/2017] [Indexed: 12/21/2022] Open
Abstract
Owing to the key role of trehalose in pathogenic organisms, there has recently been growing interest in trehalose metabolism for therapeutic purposes. Trehalose-6-phosphate phosphatase (TPP) is a pivotal enzyme in the most prominent biosynthesis pathway (OtsAB). Here, we compare the enzyme characteristics of recombinant TPPs from five important nematode and bacterial pathogens, including three novel members of this protein family. Analysis of the kinetics of trehalose-6-phosphate hydrolysis reveals that all five enzymes display a burst-like kinetic behaviour which is characterised by a decrease of the enzymatic rate after the pre-steady state. The observed super-stoichiometric burst amplitudes can be explained by multiple global conformational changes in members of this enzyme family during substrate processing. In the search for specific TPP inhibitors, the trapping of the complex conformational transitions in TPPs during the catalytic cycle may present a worthwhile strategy to explore.
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Affiliation(s)
- Megan Cross
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia
| | - Siji Rajan
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia
| | - Janine Chekaiban
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia
| | - Jake Saunders
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia
| | - Chloe Hamilton
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia
| | - Jeong-Sun Kim
- Department of Chemistry, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Mark J Coster
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia
| | - Robin B Gasser
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Andreas Hofmann
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia.
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia.
- Queensland Tropical Health Alliance, Smithfield, Queensland, 4878, Australia.
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53
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Drug-induced endovesiculation of erythrocytes is modulated by the dynamics in the cytoskeleton/membrane interaction. Blood Cells Mol Dis 2017; 64:15-22. [DOI: 10.1016/j.bcmd.2017.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/06/2017] [Accepted: 03/06/2017] [Indexed: 11/24/2022]
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Khalil AA, Jameson MJ. Sodium Orthovanadate Inhibits Proliferation and Triggers Apoptosis in Oral Squamous Cell Carcinoma in vitro. BIOCHEMISTRY (MOSCOW) 2017; 82:149-155. [PMID: 28320298 DOI: 10.1134/s0006297917020067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Sodium orthovanadate (SOV) is a general inhibitor of tyrosine phosphatases, a large family of enzymes that catalyze the removal of phosphate groups from tyrosine residues. SOV is commonly used in the laboratory to preserve the protein tyrosyl phosphorylation state of proteins under study. It has shown promising antineoplastic activity in some human cancer cell lines; this effect has not been fully investigated in head and neck squamous cell carcinoma. In this study, the effect of SOV on cell growth, proliferation, viability, and apoptosis was assessed in Cal27 cells, an oral squamous cell carcinoma (OSCC) cell line. SOV exhibited dose-dependent inhibition of cell growth and decrease in cell viability and colony formation. The IC50 values for treatment lasting 72 h and 7 days were 25 and 10 µM, respectively. The cytotoxic effect of the drug was associated with poly(ADP-ribose)polymerase cleavage detected by immunoblot. Flow cytometry of Cal27 cells stained with annexin V-FITC and propidium iodide showed a dose-dependent increase in apoptosis that reached approximately 40% at 25 µM SOV. These findings demonstrate that SOV has in vitro antiproliferative and proapoptotic effect on OSCC cells.
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Affiliation(s)
- A A Khalil
- University of Virginia Health System, Division of Head and Neck Oncologic and Microvascular Surgery, Department of Otolaryngology, Head and Neck Surgery, Virginia, USA.
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55
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Shah M, Smolko CM, Kinicki S, Chapman ZD, Brautigan DL, Janes KA. Profiling Subcellular Protein Phosphatase Responses to Coxsackievirus B3 Infection of Cardiomyocytes. Mol Cell Proteomics 2017; 16:S244-S262. [PMID: 28174228 DOI: 10.1074/mcp.o116.063487] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 01/31/2017] [Indexed: 01/23/2023] Open
Abstract
Cellular responses to stimuli involve dynamic and localized changes in protein kinases and phosphatases. Here, we report a generalized functional assay for high-throughput profiling of multiple protein phosphatases with subcellular resolution and apply it to analyze coxsackievirus B3 (CVB3) infection counteracted by interferon signaling. Using on-plate cell fractionation optimized for adherent cells, we isolate protein extracts containing active endogenous phosphatases from cell membranes, the cytoplasm, and the nucleus. The extracts contain all major classes of protein phosphatases and catalyze dephosphorylation of plate-bound phosphosubstrates in a microtiter format, with cellular activity quantified at the end point by phosphospecific ELISA. The platform is optimized for six phosphosubstrates (ERK2, JNK1, p38α, MK2, CREB, and STAT1) and measures specific activities from extracts of fewer than 50,000 cells. The assay was exploited to examine viral and antiviral signaling in AC16 cardiomyocytes, which we show can be engineered to serve as susceptible and permissive hosts for CVB3. Phosphatase responses were profiled in these cells by completing a full-factorial experiment for CVB3 infection and type I/II interferon signaling. Over 850 functional measurements revealed several independent, subcellular changes in specific phosphatase activities. During CVB3 infection, we found that type I interferon signaling increases subcellular JNK1 phosphatase activity, inhibiting nuclear JNK1 activity that otherwise promotes viral protein synthesis in the infected host cell. Our assay provides a high-throughput way to capture perturbations in important negative regulators of intracellular signal-transduction networks.
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Affiliation(s)
- Millie Shah
- From the ‡Department of Biomedical Engineering
| | | | | | | | - David L Brautigan
- the ‖Center for Cell Signaling and Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908
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56
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Bass JJ, Wilkinson DJ, Rankin D, Phillips BE, Szewczyk NJ, Smith K, Atherton PJ. An overview of technical considerations for Western blotting applications to physiological research. Scand J Med Sci Sports 2017; 27:4-25. [PMID: 27263489 PMCID: PMC5138151 DOI: 10.1111/sms.12702] [Citation(s) in RCA: 221] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2016] [Indexed: 12/11/2022]
Abstract
The applications of Western/immunoblotting (WB) techniques have reached multiple layers of the scientific community and are now considered routine procedures in the field of physiology. This is none more so than in relation to skeletal muscle physiology (i.e., resolving the mechanisms underpinning adaptations to exercise). Indeed, the inclusion of WB data is now considered an essential aspect of many such physiological publications to provide mechanistic insight into regulatory processes. Despite this popularity, and due to the ubiquitous and relatively inexpensive availability of WB equipment, the quality of WB in publications and subsequent analysis and interpretation of the data can be variable, perhaps resulting in spurious conclusions. This may be due to poor laboratory technique and/or lack of comprehension of the critical steps involved in WB and what quality control procedures should be in place to ensure robust data generation. The present review aims to provide a detailed description and critique of WB procedures and technicalities, from sample collection through preparation, blotting and detection, to analysis of the data collected. We aim to provide the reader with improved expertise to critically conduct, evaluate, and troubleshoot the WB process, to produce reproducible and reliable blots.
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Affiliation(s)
- J J Bass
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Medicine, University of Nottingham, Derby, UK
| | - D J Wilkinson
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Medicine, University of Nottingham, Derby, UK
| | - D Rankin
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Medicine, University of Nottingham, Derby, UK
| | - B E Phillips
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Medicine, University of Nottingham, Derby, UK
| | - N J Szewczyk
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Medicine, University of Nottingham, Derby, UK
| | - K Smith
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Medicine, University of Nottingham, Derby, UK
| | - P J Atherton
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research, School of Medicine, University of Nottingham, Derby, UK
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57
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Fusi F, Spiga O, Trezza A, Sgaragli G, Saponara S. The surge of flavonoids as novel, fine regulators of cardiovascular Ca v channels. Eur J Pharmacol 2016; 796:158-174. [PMID: 28012974 DOI: 10.1016/j.ejphar.2016.12.033] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 12/15/2016] [Accepted: 12/20/2016] [Indexed: 01/28/2023]
Abstract
Ion channels underlie a wide variety of physiological processes that involve rapid changes in cell dynamics, such as cardiac and vascular smooth muscle contraction. Overexpression or dysfunction of these membrane proteins are the basis of many cardiovascular diseases that represent the leading cause of morbidity and mortality for human beings. In the last few years, flavonoids, widely distributed in the plant kingdom, have attracted the interest of many laboratories as an emerging class of fine ion, in particular Cav, channels modulators. Pieces of in vitro evidence for direct as well as indirect effects exerted by various flavonoids on ion channel currents are now accumulating in the scientific literature. This activity may be responsible, at least in part, for the beneficial and protective effects of dietary flavonoids toward cardiovascular diseases highlighted in several epidemiological studies. Here we examine numerous studies aimed at analysing this feature of flavonoids, focusing on the mechanisms that promote their sometimes controversial activities at cardiovascular Cav channels. New methodological approaches, such as molecular modelling and docking to Cav1.2 channel α1c subunit, used to elucidate flavonoids intrinsic mechanism of action, are introduced. Moreover, flavonoid-membrane interaction, bioavailability, and antioxidant activity are taken into account and discussed.
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Affiliation(s)
- Fabio Fusi
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy.
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - Alfonso Trezza
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - Giampietro Sgaragli
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - Simona Saponara
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
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58
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Liu J, Fu H, Chang F, Wang J, Zhang S, Caudle Y, Zhao J, Yin D. Sodium orthovanadate suppresses palmitate-induced cardiomyocyte apoptosis by regulation of the JAK2/STAT3 signaling pathway. Apoptosis 2016; 21:546-57. [PMID: 26921179 DOI: 10.1007/s10495-016-1231-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Elevated circulatory free fatty acids (FFAs) especially saturated FFAs, such as palmitate (PA), are detrimental to the heart. However, mechanisms responsible for this phenomenon remain unknown. Here, the role of JAK2/STAT3 in PA-induced cytotoxicity was investigated in cardiomyocytes. We demonstrate that PA suppressed the JAK2/STAT3 pathway by dephosphorylation of JAK2 (Y1007/1008) and STAT3 (Y705), and thus blocked the translocation of STAT3 into the nucleus. Conversely, phosphorylation of S727, another phosphorylated site of STAT3, was increased in response to PA treatment. Pretreatment of JNK inhibitor, but not p38 MAPK inhibitor, inhibited STAT3 (S727) activation induced by PA and rescued the phosphorylation of STAT3 (Y705). The data suggested that JNK may be another upstream factor regulating STAT3, and verified the important function of P-STAT3 (Y705) in PA-induced cardiomyocyte apoptosis. Sodium orthovanadate (SOV), a protein tyrosine phosphatase inhibitor, obviously inhibited PA-induced apoptosis by restoring JAK2/STAT3 pathways. This effect was diminished by STAT3 inhibitor Stattic. Collectively, our data suggested a novel mechanism that the inhibition of JAK2/STAT3 activation was responsible for palmitic lipotoxicity and SOV may act as a potential therapeutic agent by targeting JAK2/STAT3 in lipotoxic cardiomyopathy treatment.
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Affiliation(s)
- Jing Liu
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, 250100, People's Republic of China
| | - Hui Fu
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, 250100, People's Republic of China
| | - Fen Chang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, 250100, People's Republic of China
| | - Jinlan Wang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, 250100, People's Republic of China
| | - Shangli Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, 250100, People's Republic of China
| | - Yi Caudle
- Department of Internal Medicine, College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
| | - Jing Zhao
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, 250100, People's Republic of China.
| | - Deling Yin
- School of Pharmacy, Central South University, Changsha, 410023, People's Republic of China.
- Department of Internal Medicine, College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA.
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59
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Hadžibrahimović M, Sužnjević D, Pastor F, Cvetić Antić T, Žižić M, Zakrzewska J, Živić M. The interactions of vanadate monomer with the mycelium of fungus Phycomyces blakesleeanus: reduction or uptake? Antonie van Leeuwenhoek 2016; 110:365-373. [PMID: 27896685 DOI: 10.1007/s10482-016-0808-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Accepted: 11/21/2016] [Indexed: 11/26/2022]
Abstract
The possibility of reduction of vanadate monomer in the mycelium of fungus Phycomyces blakesleeanus was investigated in this study by means of polarography. Control experiments were performed with vanadyl [V(IV)] and vanadate [V(V)] in 10 mM Hepes, pH 7.2. Addition of P. blakesleeanus mycelium resulted in disappearance of all V(IV) polarographic waves recorded in the control. This points to the uptake of all available V(IV) by the mycelium, up to 185 µmol/gFW, and suggests P. blakesleeanus as a potential agent in V(IV) bioremediation. Polarographic measurements of mycelium with low concentrations (0.1-1 mM) of V(V), that only allows the presence of monomer, showed that fungal mycelia removes around 27% of V(V) from the extracellular solution. Uptake was saturated at 104 ± 2 µmol/gFW which indicates excellent bioaccumulation capability of P. blakesleeanus. EPR, 51V NMR and polarographic experiments showed no indications of any measurable extracellular complexation of V(V) monomer with fungal exudates, reduction by the mycelium or adsorption to the cell wall. Therefore, in contrast to vanadium oligomers, vanadate monomer interactions with the mycelium are restricted to its transport into the fungal cell, probably by a phosphate transporter.
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Affiliation(s)
- Mirzeta Hadžibrahimović
- Department of Biomedical Sciences, State University of Novi Pazar, Vuka Karadžića bb, 36300, Novi Pazar, Serbia
| | - Desanka Sužnjević
- Institute of General and Physical Chemistry, Studentski trg 12-16, 11000, Belgrade, Serbia
| | - Ferenc Pastor
- Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000, Belgrade, Serbia
| | - Tijana Cvetić Antić
- University of Belgrade-Faculty of Biology, Studentski trg 16, 11000, Belgrade, Serbia
| | - Milan Žižić
- Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030, Belgrade, Serbia
| | - Joanna Zakrzewska
- Institute of General and Physical Chemistry, Studentski trg 12-16, 11000, Belgrade, Serbia
| | - Miroslav Živić
- University of Belgrade-Faculty of Biology, Studentski trg 16, 11000, Belgrade, Serbia.
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60
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Bellomo E, Birla Singh K, Massarotti A, Hogstrand C, Maret W. The metal face of protein tyrosine phosphatase 1B. Coord Chem Rev 2016; 327-328:70-83. [PMID: 27890939 PMCID: PMC5115158 DOI: 10.1016/j.ccr.2016.07.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 07/01/2016] [Accepted: 07/01/2016] [Indexed: 01/12/2023]
Abstract
A new paradigm in metallobiochemistry describes the activation of inactive metalloenzymes by metal ion removal. Protein tyrosine phosphatases (PTPs) do not seem to require a metal ion for enzymatic activity. However, both metal cations and metal anions modulate their enzymatic activity. One binding site is the phosphate binding site at the catalytic cysteine residue. Oxyanions with structural similarity to phosphate, such as vanadate, inhibit the enzyme with nanomolar to micromolar affinities. In addition, zinc ions (Zn2+) inhibit with picomolar to nanomolar affinities. We mapped the cation binding site close to the anion binding site and established a specific mechanism of inhibition occurring only in the closed conformation of the enzyme when the catalytic cysteine is phosphorylated and the catalytic aspartate moves into the active site. We discuss this dual inhibition by anions and cations here for PTP1B, the most thoroughly investigated protein tyrosine phosphatase. The significance of the inhibition in phosphorylation signaling is becoming apparent only from the functions of PTP1B in the biological context of metal cations as cellular signaling ions. Zinc ion signals complement redox signals but provide a different type of control and longer lasting inhibition on a biological time scale owing to the specificity and affinity of zinc ions for coordination environments. Inhibitor design for PTP1B and other PTPs is a major area of research activity and interest owing to their prominent roles in metabolic regulation in health and disease, in particular cancer and diabetes. Our results explain the apparent dichotomy of both cations (Zn2+) and oxyanions such as vanadate inhibiting PTP1B and having insulin-enhancing ("anti-diabetic") effects and suggest different approaches, namely targeting PTPs in the cell by affecting their physiological modulators and considering a metallodrug approach that builds on the knowledge of the insulin-enhancing effects of both zinc and vanadium compounds.
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Affiliation(s)
- Elisa Bellomo
- Metal Metabolism Group, Division of Diabetes and Nutritional Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, UK
| | - Kshetrimayum Birla Singh
- Metal Metabolism Group, Division of Diabetes and Nutritional Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, UK
| | - Alberto Massarotti
- Dipartimento di Scienze del Farmaco, Università del Piemonte Orientale “A. Avogadro”, Novara, Italy
| | - Christer Hogstrand
- Metal Metabolism Group, Division of Diabetes and Nutritional Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, UK
| | - Wolfgang Maret
- Metal Metabolism Group, Division of Diabetes and Nutritional Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, UK
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61
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Barón L, Fara K, Zapata-Carmona H, Zuñiga L, Kong M, Signorelli J, Díaz ES, Morales P. Participation of protein kinases and phosphatases in the progesterone-induced acrosome reaction and calcium influx in human spermatozoa. Andrology 2016; 4:1073-1083. [PMID: 27696749 DOI: 10.1111/andr.12234] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/04/2016] [Accepted: 05/17/2016] [Indexed: 01/05/2023]
Abstract
In human spermatozoa, protein kinases have a role in the acrosome reaction (AR) induced by a variety of stimuli. However, there is disagreement or a lack of information regarding the role of protein kinases and phosphatases in the progesterone (P)-induced increase in intracellular calcium concentration ([Ca2+ ]i ). In addition, there are no studies regarding the role of Ser/Thr and Tyr phosphatases and there are contradictory results regarding the role of Tyr kinases in the P-induced acrosome reaction. Here, we performed a simultaneous evaluation of the involvement of protein kinases and phosphatases in the P-induced acrosome reaction and in the P-induced calcium influx. Motile spermatozoa were capacitated for 18 h and different aliquots were allocated to treated or control groups and then evaluated for their ability to undergo the acrosome reaction and to increase [Ca2+ ]i in response to P. The acrosome reaction was evaluated using Pisum sativum agglutinin (PSA)-FITC, and [Ca2+ ]i was evaluated using fura 2AM. At all of the concentrations tested, PKA inhibitors significantly reduced the percentage of the P-induced acrosome reaction (p < 0.001). However, only the highest concentrations of PKA inhibitors reduced the P-induced calcium influx; lower concentrations of PKA inhibitors did not affect it. Similar results were apparent for PKC inhibitors and for tyrosine kinase inhibitors. None of the Ser/Thr phosphatase inhibitors affected the P-induced acrosome reaction or the P-induced calcium influx, except for the PP2B inhibitors that significantly reduced the P-induced acrosome reaction without affecting calcium influx. Finally, the protein tyrosine phosphatase inhibitors significantly blocked the P-induced acrosome reaction and reduced the amplitude of the P-induced calcium transient (p < 0.001) as well as the amplitude of the plateau phase (p < 0.01). The data suggest that protein kinases and possibly PP2B have a role on the acrosome reaction at some point downstream of calcium entry and that Tyr phosphatases have a role on the acrosome reaction upstream of calcium entry.
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Affiliation(s)
- L Barón
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile
| | - K Fara
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile
| | - H Zapata-Carmona
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile
| | - L Zuñiga
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile.,Antofagasta Institute, University of Antofagasta, Antofagasta, Chile
| | - M Kong
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile
| | - J Signorelli
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile
| | - E S Díaz
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile
| | - P Morales
- Laboratory of Biology of Reproduction, Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile.,Antofagasta Institute, University of Antofagasta, Antofagasta, Chile
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62
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Eldeeb MA, Fahlman RP. Phosphorylation Impacts N-end Rule Degradation of the Proteolytically Activated Form of BMX Kinase. J Biol Chem 2016; 291:22757-22768. [PMID: 27601470 DOI: 10.1074/jbc.m116.737387] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/24/2016] [Indexed: 11/06/2022] Open
Abstract
Cellular signaling leading to the initiation of apoptosis typically results in the activation of caspases, which in turn leads to the proteolytic generation of protein fragments with new or altered cellular functions. Increasing numbers of reports are demonstrating that the activity of many of these proteolytically activated protein fragments can be attenuated by their selective degradation by the N-end rule pathway. Here we report the first evidence that selective degradation of a caspase product by the N-end rule pathway can be modulated by phosphorylation. We demonstrate that the pro-apoptotic fragment of the bone marrow kinase on chromosome X (BMX) generated by caspase cleavage in the prostate cancer-derived PC3 cell line is metabolically unstable in cells because its N-terminal tryptophan targets it for proteasomal degradation via the N-end rule pathway. In addition, we have demonstrated that phosphorylation of tyrosine 566 relatively inhibits degradation of the C-terminal BMX catalytic fragment, and this phosphorylation is crucial for its pro-apoptotic function. Overall, our results demonstrate that cleaved BMX is a novel N-end rule substrate, and its degradation exhibits a novel interplay between substrate phosphorylation and N-end rule degradation, revealing an increasing complex regulatory network of apoptotic proteolytic signaling cascades.
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Affiliation(s)
| | - Richard P Fahlman
- From the Departments of Biochemistry and .,Oncology, University of Alberta, Edmonton, Alberta T6J 2H7, Canada
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63
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Abstract
Although the association between inflammatory bowel disease (IBD) and oral hygiene has been noticed before, there has been little research on prolonged fluoride exposure as a possible risk factor. In the presented cases, exposure to fluoride seems indirectly associated with higher incidence of IBD. Fluoride toxicology and epidemiology documents frequent unspecific chronic gastrointestinal symptoms and intestinal inflammation. Efflux genes that confer resistance to environmental fluoride may select for IBD associated gut microbiota and therefore be involved in the pathogenesis. Together these multidisciplinary results argue for further investigation on the hypothesis of fluoride as a risk factor for IBD.
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Affiliation(s)
| | - Bjørn Moum
- b Department of Gastroenterology , Oslo University Hospital Ullevaal & University of Oslo , Oslo , Norway
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Donaubauer EM, Law NC, Hunzicker-Dunn ME. Follicle-Stimulating Hormone (FSH)-dependent Regulation of Extracellular Regulated Kinase (ERK) Phosphorylation by the Mitogen-activated Protein (MAP) Kinase Phosphatase MKP3. J Biol Chem 2016; 291:19701-12. [PMID: 27422819 DOI: 10.1074/jbc.m116.733972] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Indexed: 01/11/2023] Open
Abstract
Within the ovarian follicle, granulosa cells (GCs) surround and support immature oocytes. FSH promotes the differentiation and proliferation of GCs and is essential for fertility. We recently reported that ERK activation is necessary for FSH to induce key genes that define the preovulatory GC. This research focused on the phosphoregulation by FSH of ERK within GCs. FSH-stimulated ERK phosphorylation on Thr(202)/Tyr(204) was PKA-dependent, but MEK(Ser(217)/Ser(221)) phosphorylation was not regulated; rather, MEK was already active. However, treatment of GCs with the EGF receptor inhibitor AG1478, a dominant-negative RAS, an Src homology 2 domain-containing Tyr phosphatase inhibitor (NSC 87877), or the MEK inhibitor PD98059 blocked FSH-dependent ERK(Thr(202)/Tyr(204)) phosphorylation, demonstrating the requirement for upstream pathway components. We hypothesized that FSH via PKA enhances ERK phosphorylation by inhibiting the activity of a protein phosphatase that constitutively dephosphorylates ERK in the absence of FSH, allowing MEK-phosphorylated ERK to accumulate in the presence of FSH because of inactivation of the phosphatase. GCs treated with different phosphatase inhibitors permitted elimination of both Ser/Thr and Tyr phosphatases and implicated dual specificity phosphatases (DUSPs) in the dephosphorylation of ERK. Treatment with MAP kinase phosphatase (MKP3, DUSP6) inhibitors increased ERK(Thr(202)/Tyr(204)) phosphorylation in the absence of FSH to levels comparable with ERK phosphorylated in the presence of FSH. ERK co-immunoprecipitated with Myc-FLAG-tagged MKP3(DUSP6). GCs treated with MKP3(DUSP6) inhibitors blocked and PKA inhibitors enhanced dephosphorylation of recombinant ERK2-GST in an in vitro phosphatase assay. Together, these results suggest that FSH-stimulated ERK activation in GCs requires the PKA-dependent inactivation of MKP3(DUSP6).
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Affiliation(s)
- Elyse M Donaubauer
- From the School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
| | - Nathan C Law
- From the School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
| | - Mary E Hunzicker-Dunn
- From the School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
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51V NMR investigation of cell-associated vanadate species in Phycomyces blakesleeanus mycelium. Res Microbiol 2016; 167:521-8. [DOI: 10.1016/j.resmic.2016.04.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 01/18/2023]
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66
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Minor LK, Westover L, Kong Y, Patel D, Wildey MJ, Conway BR, Demarest KT. Validation of a Cell-Based Screen for Insulin Receptor Modulators by Quantification of Insulin Receptor Phosphorylation. ACTA ACUST UNITED AC 2016; 8:439-46. [PMID: 14567796 DOI: 10.1177/1087057103255280] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Stimulation of a cell with insulin initiates a signal transduction cascade that results in cellular activities that include phosphorylation of the receptor itself. Measurement of the degree of phosphorylation can serve as a marker for receptor activation. Receptor phosphorylation has been measured using Western blot analysis, which is very low throughput and not easily quantifiable. The goal of this project was to develop a cell-based assay to measure receptor phosphorylation in high throughput. This report describes a cell-based assay for insulin receptor phosphorylation that is robust and amenable to high-volume screening in a microwell format.
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Affiliation(s)
- Lisa K Minor
- Johnson & Johnson Pharmaceutical Research and Development, L L C, Spring House, PA 19477, USA.
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Selective Sensing of Tyrosine Phosphorylation in Peptides Using Terbium(III) Complexes. Int J Anal Chem 2016; 2016:3216523. [PMID: 27375742 PMCID: PMC4916314 DOI: 10.1155/2016/3216523] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 04/28/2016] [Indexed: 11/18/2022] Open
Abstract
Phosphorylation of tyrosine residues in proteins, as well as their dephosphorylation, is closely related to various diseases. However, this phosphorylation is usually accompanied by more abundant phosphorylation of serine and threonine residues in the proteins and covers only 0.05% of the total phosphorylation. Accordingly, highly selective detection of phosphorylated tyrosine in proteins is an urgent subject. In this review, recent developments in this field are described. Monomeric and binuclear Tb(III) complexes, which emit notable luminescence only in the presence of phosphotyrosine (pTyr), have been developed. There, the benzene ring of pTyr functions as an antenna and transfers its photoexcitation energy to the Tb(III) ion as the emission center. Even in the coexistence of phosphoserine (pSer) and phosphothreonine (pThr), pTyr can be efficintly detected with high selectivity. Simply by adding these Tb(III) complexes to the solutions, phosphorylation of tyrosine in peptides by protein tyrosine kinases and dephosphorylation by protein tyrosine phosphatases can be successfully visualized in a real-time fashion. Furthermore, the activities of various inhibitors on these enzymes are quantitatively evaluated, indicating a strong potential of the method for efficient screening of eminent inhibitors from a number of candidates.
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68
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Liu X, Qian B, Gao C, Huang S, Cai Y, Zhang H, Zheng X, Wang P, Zhang Z. The Putative Protein Phosphatase MoYvh1 Functions Upstream of MoPdeH to Regulate the Development and Pathogenicity in Magnaporthe oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:496-507. [PMID: 27110741 DOI: 10.1094/mpmi-11-15-0259-r] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Protein phosphatases are critical regulators in eukaryotic cells. For example, the budding yeast Saccharomyces cerevisiae dual specificity protein phosphatase (DSP) ScYvh1 regulates growth, sporulation, and glycogen accumulation. Despite such importance, functions of Yvh1 proteins in filamentous fungi are not well understood. In this study, we characterized putative protein phosphatase MoYvh1, an Yvh1 homolog in the rice blast fungus Magnaporthe oryzae. Deletion of the MoYVH1 gene resulted in significant reductions in vegetative growth, conidial production, and virulence. The ΔMoyvh1 mutant also displayed defects in cell-wall integrity and was hyposensitive to the exogenous osmotic stress. Further examination revealed that the ΔMoyvh1 mutant had defects in appressorium function and invasive hyphae growth, resulting attenuated pathogenicity. Interestingly, we found that MoYvh1 affects the scavenging of host-derived reactive oxygen species that promotes M. oryzae infection. Finally, overexpression of the phosphodiesterase MoPDEH suppressed the defects in conidia formation and pathogenicity of the ΔMoyvh1 mutant, suggesting MoYvh1 could regulate MoPDEH for its function. Our study reveals not only the importance of MoYvh1 proteins in growth, differentiation, and virulence of the rice blast fungus but, also, a genetic link between MoYvh1 and MoPDEH-cAMP signaling in this fungus.
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Affiliation(s)
- Xinyu Liu
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Bin Qian
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Chuyun Gao
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Shuohan Huang
- 2 Department of Pharmacy, Nanjing Medical University, Nanjing 210029, China; and
| | - Yongchao Cai
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Haifeng Zhang
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Xiaobo Zheng
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Ping Wang
- 3 Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, LA 70118, U.S.A
| | - Zhengguang Zhang
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
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Nitric oxide up-regulates endothelial expression of angiotensin II type 2 receptors. Biochem Pharmacol 2016; 112:24-36. [PMID: 27235748 DOI: 10.1016/j.bcp.2016.05.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/24/2016] [Indexed: 11/21/2022]
Abstract
Increasing vascular NO levels following up-regulation of endothelial nitric oxide synthase (eNOS) is considered beneficial in cardiovascular disease. Whether such beneficial effects exerted by increased NO-levels include the vascular renin-angiotensin system remains elucidated. Exposure of endothelial cells originated from porcine aorta, mouse brain and human umbilical veins to different NO-donors showed that expression of the angiotensin-II-type-2-receptor (AT2) mRNA and protein is up-regulated by activation of soluble guanylyl cyclase, protein kinase G and p38 mitogen-activated protein kinase without changing AT2 mRNA stability. In mice, endothelial-specific overexpression of eNOS stimulated, while chronic treatment with the NOS-blocker l-nitroarginine inhibited AT2 expression. The NO-induced AT2 up-regulation was associated with a profound inhibition of angiotensin-converting enzyme (ACE)-activity. In endothelial cells this reduction of ACE-activity was reversed by either the AT2 antagonist PD 123119 or by inhibition of transcription with actinomycin D. Furthermore, in C57Bl/6 mice an acute i.v. bolus of l-nitroarginine did not change AT2-expression and ACE-activity suggesting that inhibition of ACE-activity by endogenous NO is crucially dependent on AT2 protein level. Likewise, three weeks of either voluntary or forced exercise training increased AT2 expression and reduced ACE-activity in C57Bl/6 but not in mice lacking eNOS suggesting significance of this signaling interaction for vascular physiology. Finally, aortic AT2 expression is about 5 times greater in female as compared to male C57Bl/6 and at the same time aortic ACE activity is reduced in females by more than 50%. Together these findings imply that endothelial NO regulates AT2 expression and that AT2 may regulate ACE-activity.
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70
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Roth S, Spalinger MR, Gottier C, Biedermann L, Zeitz J, Lang S, Weber A, Rogler G, Scharl M. Bilberry-Derived Anthocyanins Modulate Cytokine Expression in the Intestine of Patients with Ulcerative Colitis. PLoS One 2016; 11:e0154817. [PMID: 27152519 PMCID: PMC4859486 DOI: 10.1371/journal.pone.0154817] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 04/19/2016] [Indexed: 01/30/2023] Open
Abstract
Background/Aims We previously demonstrated that anthocyanin-rich bilberry extract (ARBE) inhibits IFN-γ-induced signalling and downstream effects in human monocytic cells and ameliorates disease activity in ulcerative colitis (UC) patients. Here, we studied the molecular mechanisms of ARBE-mediated effects in vitro and by analysing colonic tissue and serum samples of UC patients treated with an oral anthocyanin-rich bilberry preparation during an open label clinical trial. Methods Colon specimens obtained during an open pilot study using ARBE for the treatment of mild-to-moderate UC were analyzed by immunohistochemistry. Cytokine levels in patients’ serum were quantified by ELISA. Cell culture experiments were performed using THP-1 monocytic cells. Results ARBE treatment inhibited the expression of IFN-γ-receptor 2 in human THP-1 monocytic cells. Colon biopsies of UC patients who responded to the 6-week long ARBE treatment revealed reduced amounts of the pro-inflammatory cytokines IFN-γ and TNF-α. Levels of phosphorylated (activated) p65-NF-κB were reduced in these patients. Further, patients with successful ARBE treatment featured enhanced levels of Th17-cell specific cytokine IL-22 and immunoregulatory cytokine IL-10 as well as reduced serum levels of TNF-α and MCP-1, but enhanced levels of IL-17A, in contrast to patients that did not reach remission after ARBE treatment. Conclusions Our data suggest a molecular mechanism underlying the anti-inflammatory effects of ARBE treatment in UC patients by modulating T-cell cytokine signalling and inhibiting IFN-γ signal transduction. These data are of particular interest, since ARBE is a promising therapeutic approach for the treatment of IBD.
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Affiliation(s)
- Sofia Roth
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Marianne R. Spalinger
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Claudia Gottier
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Luc Biedermann
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Jonas Zeitz
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Silvia Lang
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Achim Weber
- Institute for Surgical Pathology, University Hospital Zürich, Zurich, Switzerland
| | - Gerhard Rogler
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Michael Scharl
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
- * E-mail:
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71
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Lange-Asschenfeldt C, Schäble S, Suvorava T, Fahimi EG, Bisha M, Stermann T, Henning U, Kojda G. Effects of varenicline on alpha4-containing nicotinic acetylcholine receptor expression and cognitive performance in mice. Neuropharmacology 2016; 107:100-110. [PMID: 27012889 DOI: 10.1016/j.neuropharm.2016.03.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 02/26/2016] [Accepted: 03/18/2016] [Indexed: 10/22/2022]
Abstract
Nicotinic acetylcholine receptor (nAChR) subtypes containing the α4 subunit, particularly α4β2 nAChRs, play an important role in cognitive functioning. The impact of the smoking cessation aid varenicline, a selective partial α4β2 nAChR agonist, on (1) changes of central protein and mRNA expression of this receptor and (2) on memory deficits in a mouse model of cognitive impairment was investigated. Protein and mRNA expression of both the α4 and β2 receptor subunits in mouse brain endothelial and hippocampal cells as well as hippocampus and neocortex tissues were determined by western blot and realtime PCR, respectively. The β2 antibody showed low specificity, though. Tissues were examined following a 2-week oral treatment with various doses of varenicline (0.01, 0.1, 1, 3 mg/kg/day) or vehicle. In addition, episodic memory of mice was assessed following this treatment with an object recognition task using (1) normal mice and (2) animals with anticholinergic-induced memory impairment (i.p. injection of 0.5 mg/kg scopolamine). Varenicline dose-dependently increased protein expression of both the α4 and β2 subunit in cell cultures and brain tissues, respectively, but had no effect on mRNA expression of both subunits. Scopolamine injection induced a significant reduction of object memory in vehicle-treated mice. By contrast, cognitive performance was not altered by scopolamine in varenicline-treated mice. In conclusion, a 2-week oral treatment with varenicline prevented memory impairment in the scopolamine mouse model. In parallel, protein, but not mRNA expression was upregulated, suggesting a posttranscriptional mechanism. Our findings suggest a beneficial effect of varenicline on cognitive dysfunction.
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Affiliation(s)
| | - Sandra Schäble
- Comparative Psychology, Institute of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Tatsiana Suvorava
- Department of Pharmacology and Clinical Pharmacology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Ehsan Gholamreza Fahimi
- Department of Pharmacology and Clinical Pharmacology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Marion Bisha
- Department of Pharmacology and Clinical Pharmacology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Torben Stermann
- Department of Pharmacology and Clinical Pharmacology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany; Leibniz Center for Diabetes Research, Heinrich-Heine-University, Düsseldorf, Germany
| | - Uwe Henning
- Department of Psychiatry and Psychotherapy, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Georg Kojda
- Department of Pharmacology and Clinical Pharmacology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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72
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Uhrig RG, Labandera AM, Muhammad J, Samuel M, Moorhead GB. Rhizobiales-like Phosphatase 2 from Arabidopsis thaliana Is a Novel Phospho-tyrosine-specific Phospho-protein Phosphatase (PPP) Family Protein Phosphatase. J Biol Chem 2016; 291:5926-5934. [PMID: 26742850 DOI: 10.1074/jbc.m115.683656] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Indexed: 12/13/2022] Open
Abstract
Cellular signaling through protein tyrosine phosphorylation is well established in mammalian cells. Although lacking the classic tyrosine kinases present in humans, plants have a tyrosine phospho-proteome that rivals human cells. Here we report a novel plant tyrosine phosphatase from Arabidopsis thaliana (AtRLPH2) that, surprisingly, has the sequence hallmarks of a phospho-serine/threonine phosphatase belonging to the PPP family. Rhizobiales/Rhodobacterales/Rhodospirillaceae-like phosphatases (RLPHs) are conserved in plants and several other eukaryotes, but not in animals. We demonstrate that AtRLPH2 is localized to the plant cell cytosol, is resistant to the classic serine/threonine phosphatase inhibitors okadaic acid and microcystin, but is inhibited by the tyrosine phosphatase inhibitor orthovanadate and is particularly sensitive to inhibition by the adenylates, ATP and ADP. AtRLPH2 displays remarkable selectivity toward tyrosine-phosphorylated peptides versus serine/threonine phospho-peptides and readily dephosphorylates a classic tyrosine phosphatase protein substrate, suggesting that in vivo it is a tyrosine phosphatase. To date, only one other tyrosine phosphatase is known in plants; thus AtRLPH2 represents one of the missing pieces in the plant tyrosine phosphatase repertoire and supports the concept of protein tyrosine phosphorylation as a key regulatory event in plants.
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Affiliation(s)
- R Glen Uhrig
- From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada
| | - Anne-Marie Labandera
- From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada
| | - Jamshed Muhammad
- From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada
| | - Marcus Samuel
- From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada
| | - Greg B Moorhead
- From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada.
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Scior T, Guevara-Garcia JA, Do QT, Bernard P, Laufer S. Why Antidiabetic Vanadium Complexes are Not in the Pipeline of "Big Pharma" Drug Research? A Critical Review. Curr Med Chem 2016; 23:2874-2891. [PMID: 26997154 PMCID: PMC5068500 DOI: 10.2174/0929867323666160321121138] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 12/18/2022]
Abstract
Public academic research sites, private institutions as well as small companies have made substantial contributions to the ongoing development of antidiabetic vanadium compounds. But why is this endeavor not echoed by the globally operating pharmaceutical companies, also known as "Big Pharma"? Intriguingly, today's clinical practice is in great need to improve or replace insulin treatment against Diabetes Mellitus (DM). Insulin is the mainstay therapeutically and economically. So, why do those companies develop potential antidiabetic drug candidates without vanadium (vanadium- free)? We gathered information about physicochemical and pharmacological properties of known vanadium-containing antidiabetic compounds from the specialized literature, and converted the data into explanations (arguments, the "pros and cons") about the underpinnings of antidiabetic vanadium. Some discoveries were embedded in chronological order while seminal reviews of the last decade about the Medicinal chemistry of vanadium and its history were also listed for further understanding. In particular, the concepts of so-called "noncomplexed or free" vanadium species (i.e. inorganic oxido-coordinated species) and "biogenic speciation" of antidiabetic vanadium complexes were found critical and subsequently documented in more details to answer the question.
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Affiliation(s)
- Thomas Scior
- Department of Pharmacy, Faculty of Chemical Sciences, University Benemerita Universidad Autonoma de Puebla, P.O. Box: 72570, City of Puebla, Country Mexico.
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74
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Meitinger F, Palani S, Pereira G. Detection of Phosphorylation Status of Cytokinetic Components. Methods Mol Biol 2016; 1369:219-37. [PMID: 26519316 DOI: 10.1007/978-1-4939-3145-3_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Yeast cells can be easily cultured, synchronized, and genetically modified making them a convenient model system to study molecular mechanisms underlying cytokinesis. Here, we describe simple methods that allow the analysis of the phosphorylation profile of cytokinetic proteins, both in vivo and in vitro, using standard laboratory equipment. In addition, we compare the ability of three different, standard, and optimized acrylamide gel conditions to separate phosphorylated forms, using the protein Inn1 as an example.
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Affiliation(s)
- Franz Meitinger
- DKFZ-ZMBH Alliance, German Cancer Research Center (DKFZ), University of Heidelberg, Im Neuenheimer Feld 581, Heidelberg, 69120, Germany.,Ludwig Institute for Cancer Research, 9500 Gilman Drive, CMM East, La Jolla, CA, 92093, USA
| | - Saravanan Palani
- Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Gislene Pereira
- DKFZ-ZMBH Alliance, German Cancer Research Center (DKFZ), University of Heidelberg, Im Neuenheimer Feld 581, Heidelberg, 69120, Germany.
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Moise G, Gallup NM, Alexandrova AN, Hengge AC, Johnson SJ. Conservative tryptophan mutants of the protein tyrosine phosphatase YopH exhibit impaired WPD-loop function and crystallize with divanadate esters in their active sites. Biochemistry 2015; 54:6490-500. [PMID: 26445170 DOI: 10.1021/acs.biochem.5b00496] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Catalysis in protein tyrosine phosphatases (PTPs) involves movement of a protein loop called the WPD loop that brings a conserved aspartic acid into the active site to function as a general acid. Mutation of the tryptophan in the WPD loop of the PTP YopH to any other residue with a planar, aromatic side chain (phenylalanine, tyrosine, or histidine) disables general acid catalysis. Crystal structures reveal these conservative mutations leave this critical loop in a catalytically unproductive, quasi-open position. Although the loop positions in crystal structures are similar for all three conservative mutants, the reasons inhibiting normal loop closure differ for each mutant. In the W354F and W354Y mutants, steric clashes result from six-membered rings occupying the position of the five-membered ring of the native indole side chain. The histidine mutant dysfunction results from new hydrogen bonds stabilizing the unproductive position. The results demonstrate how even modest modifications can disrupt catalytically important protein dynamics. Crystallization of all the catalytically compromised mutants in the presence of vanadate gave rise to vanadate dimers at the active site. In W354Y and W354H, a divanadate ester with glycerol is observed. Such species have precedence in solution and are known from the small molecule crystal database. Such species have not been observed in the active site of a phosphatase, as a functional phosphatase would rapidly catalyze their decomposition. The compromised functionality of the mutants allows the trapping of species that undoubtedly form in solution and are capable of binding at the active sites of PTPs, and, presumably, other phosphatases. In addition to monomeric vanadate, such higher-order vanadium-based molecules are likely involved in the interaction of vanadate with PTPs in solution.
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Affiliation(s)
- Gwendolyn Moise
- Department of Chemistry and Biochemistry, Utah State University , Logan, Utah 84322-0300, United States
| | - Nathan M Gallup
- Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095-1569, United States
| | - Anastassia N Alexandrova
- Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095-1569, United States.,California Nanosystems Institute, University of California , Los Angeles, California 90095-1569, United States
| | - Alvan C Hengge
- Department of Chemistry and Biochemistry, Utah State University , Logan, Utah 84322-0300, United States
| | - Sean J Johnson
- Department of Chemistry and Biochemistry, Utah State University , Logan, Utah 84322-0300, United States
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A respiratory chain controlled signal transduction cascade in the mitochondrial intermembrane space mediates hydrogen peroxide signaling. Proc Natl Acad Sci U S A 2015; 112:E5679-88. [PMID: 26438848 DOI: 10.1073/pnas.1517932112] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) govern cellular homeostasis by inducing signaling. H2O2 modulates the activity of phosphatases and many other signaling molecules through oxidation of critical cysteine residues, which led to the notion that initiation of ROS signaling is broad and nonspecific, and thus fundamentally distinct from other signaling pathways. Here, we report that H2O2 signaling bears hallmarks of a regular signal transduction cascade. It is controlled by hierarchical signaling events resulting in a focused response as the results place the mitochondrial respiratory chain upstream of tyrosine-protein kinase Lyn, Lyn upstream of tyrosine-protein kinase SYK (Syk), and Syk upstream of numerous targets involved in signaling, transcription, translation, metabolism, and cell cycle regulation. The active mediators of H2O2 signaling colocalize as H2O2 induces mitochondria-associated Lyn and Syk phosphorylation, and a pool of Lyn and Syk reside in the mitochondrial intermembrane space. Finally, the same intermediaries control the signaling response in tissues and species responsive to H2O2 as the respiratory chain, Lyn, and Syk were similarly required for H2O2 signaling in mouse B cells, fibroblasts, and chicken DT40 B cells. Consistent with a broad role, the Syk pathway is coexpressed across tissues, is of early metazoan origin, and displays evidence of evolutionary constraint in the human. These results suggest that H2O2 signaling is under control of a signal transduction pathway that links the respiratory chain to the mitochondrial intermembrane space-localized, ubiquitous, and ancient Syk pathway in hematopoietic and nonhematopoietic cells.
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McLauchlan CC, Peters BJ, Willsky GR, Crans DC. Vanadium–phosphatase complexes: Phosphatase inhibitors favor the trigonal bipyramidal transition state geometries. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.12.012] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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78
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Darovic S, Prpar Mihevc S, Župunski V, Gunčar G, Štalekar M, Lee YB, Shaw CE, Rogelj B. Phosphorylation of C-terminal tyrosine residue 526 in FUS impairs its nuclear import. J Cell Sci 2015; 128:4151-9. [PMID: 26403203 DOI: 10.1242/jcs.176602] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/17/2015] [Indexed: 12/13/2022] Open
Abstract
Aberrant cytoplasmic aggregation of FUS, which is caused by mutations primarily in the C-terminal nuclear localisation signal, is associated with 3% of cases of familial amyotrophic lateral sclerosis (ALS). FUS aggregates are also pathognomonic for 10% of all frontotemporal lobar degeneration (FTLD) cases; however, these cases are not associated with mutations in the gene encoding FUS. This suggests that there are differences in the mechanisms that drive inclusion formation of FUS in ALS and FTLD. Here, we show that the C-terminal tyrosine residue at position 526 of FUS is crucial for normal nuclear import. This tyrosine is subjected to phosphorylation, which reduces interaction with transportin 1 and might consequentially affect the transport of FUS into the nucleus. Furthermore, we show that this phosphorylation can occur through the activity of the Src family of kinases. Our study implicates phosphorylation as an additional mechanism by which nuclear transport of FUS might be regulated and potentially perturbed in ALS and FTLD.
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Affiliation(s)
- Simona Darovic
- Jožef Stefan Institute, Department of Biotechnology, Jamova 39, Ljubljana 1000, Slovenia
| | - Sonja Prpar Mihevc
- Jožef Stefan Institute, Department of Biotechnology, Jamova 39, Ljubljana 1000, Slovenia
| | - Vera Župunski
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Gregor Gunčar
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Maja Štalekar
- Jožef Stefan Institute, Department of Biotechnology, Jamova 39, Ljubljana 1000, Slovenia
| | - Youn-Bok Lee
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, King's College London, London SE5 9RT, UK
| | - Christopher E Shaw
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, King's College London, London SE5 9RT, UK
| | - Boris Rogelj
- Jožef Stefan Institute, Department of Biotechnology, Jamova 39, Ljubljana 1000, Slovenia Biomedical Research Institute BRIS, Puhova 10, Ljubljana 1000, Slovenia
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79
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Žižić M, Dučić T, Grolimund D, Bajuk-Bogdanović D, Nikolic M, Stanić M, Križak S, Zakrzewska J. X-ray absorption near-edge structure micro-spectroscopy study of vanadium speciation in Phycomyces blakesleeanus mycelium. Anal Bioanal Chem 2015; 407:7487-96. [DOI: 10.1007/s00216-015-8916-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/08/2015] [Accepted: 07/13/2015] [Indexed: 10/24/2022]
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80
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Chinopoulos C, Kiss G, Kawamata H, Starkov AA. Measurement of ADP-ATP exchange in relation to mitochondrial transmembrane potential and oxygen consumption. Methods Enzymol 2015; 542:333-48. [PMID: 24862274 DOI: 10.1016/b978-0-12-416618-9.00017-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have previously described a fluorometric method to measure ADP-ATP exchange rates in mitochondria of permeabilized cells, in which several enzymes that consume substantial amounts of ATP and other competing reactions interconverting adenine nucleotides are present. This method relies on recording changes in free extramitochondrial Mg(2+) with the Mg(2+)-sensitive fluorescent indicator Magnesium Green (MgGr)™, exploiting the differential affinity of ADP and ATP for Mg(2+). In particular, cells are permeabilized with digitonin in the presence of BeF3(-) and Na3VO4, inhibiting all ATP- and ADP-utilizing reactions but mitochondrial exchange of ATP with ADP catalyzed by the adenine nucleotide translocase. The rate of ATP appearing in the medium upon the addition of ADP to energized mitochondria is then calculated from the rate of change in free extramitochondrial Mg(2+) using standard binding equations. Here, we describe a variant of this method involving an improved calibration step. This step minimizes errors that may be introduced during the conversion of the MgGr™ signal into free extramitochondrial [Mg(2+)] and ATP. Furthermore, we describe an approach for combining this methodology with the measurement of mitochondrial membrane potential and oxygen consumption in the same sample. The method described herein is useful for the study of malignant cells, which are known to thrive in hypoxic environments and to harbor mitochondria with profound functional alterations.
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Affiliation(s)
| | - Gergely Kiss
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | - Hibiki Kawamata
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, USA
| | - Anatoly A Starkov
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, USA
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81
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Wang Y, Liu W, Du J, Yu Y, Liang N, Liang M, Yao G, Cui S, Huang H, Sun F. NGF promotes mouse granulosa cell proliferation by inhibiting ESR2 mediated down-regulation of CDKN1A. Mol Cell Endocrinol 2015; 406:68-77. [PMID: 25737208 DOI: 10.1016/j.mce.2015.02.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 02/02/2015] [Accepted: 02/22/2015] [Indexed: 10/23/2022]
Abstract
Nerve growth factor (NGF) is known to play key roles in ovarian follicular development, such as the assembly of early follicles and follicular ovulation through its high-affinity receptor, tyrosine kinase receptor A (trkA). Herein, the molecular mechanism controlling NGF-induced granulosa cell (GC) proliferation was not clear. In this study, we found that NGF is abundant in preantral GCs and knockdown of trkA in GCs attenuated NGF-induced GC proliferation and further decreased the levels of phosphorylated extracellular regulated protein kinases 1/2 (ERK1/2). Cyclin-dependent kinase inhibitor 1A (CDKN1A), also named p21, a factor which could be either a negative or a positive regulator via transformation related protein 53 (TRP53, also named p53)-dependent or independent pathways in cell proliferation, was up-regulated during the process of NGF-induced GC proliferation. Blockade of trkA (K252α) and ERK1/2 (U0126) in GCs decreased NGF-induced expression of CDKN1A and did not alter the expression of TRP53, indicating that NGF stimulates CDKN1A expression via the trkA-ERK1/2 pathway in a TRP53-independent manner. Meanwhile, ESR2, a tumor suppressor which is exclusively expressed in GCs, was suppressed in NGF-induced GC proliferation, and this effect was abrogated by U0126. Blockade of ESR2 (ICI182,780) caused the promotion of GC proliferation and CDKN1A expression, indicating that ESR2 may be downstream of the ERK1/2 pathway in mediating the effect of CDKN1A on NGF-induced GC proliferation. Therefore, ESR2 may be involved in the integration of intracellular signal cascades and cell cycle proteins in affecting GC proliferation. Here, we provide mechanistic insights into the roles of CDKN1A in NGF-induced GC proliferation. Understanding potential cross-points between CDKN1A and ESR2 affecting GC proliferation will help in the discovery of new therapeutic targets in some female infertility disorders.
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Affiliation(s)
- Yong Wang
- International Peace Maternity & Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200030, China
| | - Wenjing Liu
- College of Life Science and Technology, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China
| | - Juan Du
- Xinxiang Medical College, Henan 453003, China
| | - Yang Yu
- Jinzhou Medical College, Liaoning 121001, China
| | - Ning Liang
- International Peace Maternity & Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200030, China
| | - Meng Liang
- International Peace Maternity & Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200030, China
| | - Guidong Yao
- International Peace Maternity & Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200030, China
| | - Sheng Cui
- China Agricultural University, Beijing 100094, China
| | - Hefeng Huang
- International Peace Maternity & Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200030, China; Shanghai Key Laboratory of Reproductive Medicine, Shanghai 200025, China
| | - Fei Sun
- International Peace Maternity & Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200030, China; Shanghai Key Laboratory of Reproductive Medicine, Shanghai 200025, China.
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82
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Christodoulou A, Yokoyama H. Purification of nuclear localization signal-containing proteins and its application to investigation of the mechanisms of the cell division cycle. Small GTPases 2015; 6:20-7. [PMID: 25862163 PMCID: PMC4601338 DOI: 10.4161/21541248.2014.978162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The GTP bound form of the Ran GTPase (RanGTP) in the nucleus promotes nuclear import of the proteins bearing nuclear localization signals (NLS). When nuclear envelopes break down during mitosis, RanGTP is locally produced around chromosomes and drives the assembly of the spindle early in mitosis and the nuclear envelope (NE) later. RanGTP binds to the heterodimeric nuclear transport receptor importin α/β and releases NLS proteins from the receptor. Liberated NLS proteins around chromosomes have been shown to play distinct, essential roles in spindle and NE assembly. Here we provide a highly specific protocol to purify NLS proteins from crude cell lysates. The pure NLS fraction is an excellent resource to investigate the NLS protein function and identify new mitotic regulators, uncovering fundamental mechanisms of the cell division cycle. It takes 2–3 days to obtain the NLS fraction.
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83
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Chen TT, Filvaroff E, Peng J, Marsters S, Jubb A, Koeppen H, Merchant M, Ashkenazi A. MET Suppresses Epithelial VEGFR2 via Intracrine VEGF-induced Endoplasmic Reticulum-associated Degradation. EBioMedicine 2015; 2:406-20. [PMID: 26137585 PMCID: PMC4486192 DOI: 10.1016/j.ebiom.2015.03.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 03/26/2015] [Accepted: 03/27/2015] [Indexed: 12/16/2022] Open
Abstract
Hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) drive cancer through their respective receptors, MET and VEGF receptor 2 (VEGFR2). VEGFR2 inhibits MET by promoting MET dephosphorylation. However, whether MET conversely regulates VEGFR2 remains unknown. Here we show that MET suppresses VEGFR2 protein by inducing its endoplasmic-reticulum-associated degradation (ERAD), via intracrine VEGF action. HGF-MET signaling in epithelial cancer cells promoted VEGF biosynthesis through PI3-kinase. In turn, VEGF and VEGFR2 associated within the ER, activating inositol-requiring enzyme 1α, and thereby facilitating ERAD-mediated depletion of VEGFR2. MET disruption upregulated VEGFR2, inducing compensatory tumor growth via VEGFR2 and MEK. However, concurrent disruption of MET and either VEGF or MEK circumvented this, enabling more profound tumor inhibition. Our findings uncover unique cross-regulation between MET and VEGFR2-two RTKs that play significant roles in tumor malignancy. Furthermore, these results suggest rational combinatorial strategies for targeting RTK signaling pathways more effectively, which has potentially important implications for cancer therapy.
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Affiliation(s)
- Tom T Chen
- Cancer Immunology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
| | - Ellen Filvaroff
- Cancer Immunology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jing Peng
- In Vivo Pharmacology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
| | - Scot Marsters
- Cancer Immunology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
| | - Adrian Jubb
- Research Pathology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
| | - Hartmut Koeppen
- Research Pathology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
| | - Mark Merchant
- In Vivo Pharmacology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
| | - Avi Ashkenazi
- Cancer Immunology, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA
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84
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Šimkovič M, Olejníková P, Mat'at'a M, Žemla P, Vilimová V, Farkašová L, Varečka L. Nutrient transport into germinating Trichoderma atroviride conidia and development of its driving force. MICROBIOLOGY-SGM 2015; 161:1240-50. [PMID: 25777081 DOI: 10.1099/mic.0.000079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The exit from dormancy and the start of growth should be preceded or at least accompanied by the uptake of nutrients. In this work we studied changes in the transport of several nutrients into Trichoderma atroviride conidia. Germination started with a short period of isodiametric growth (conidial swelling), followed by polarized growth (germ tube formation) after about 8 h at 26 °C. The onset of isodiametric growth required the presence of external both phosphate and nitrate. At the same time, an increased uptake of precursors of macromolecules and phospholipids ((14)C- or (3)H-labelled valine, uracil, N-acetylglucosamine and choline) occurred. A low uptake of these precursors was observed also in non-germinating conidia. Concomitantly, this uptake developed an increased sensitivity to the uncoupler 3,3',4',5-tetrachlorosalicylanilide. Expression and activity of H(+)-ATPase started after completing isodiametric growth, suggesting that the proton-motive force (PMF) generated by H(+)-ATPase may be an accelerator of nutrient uptake and metabolism. (14)C-valine uptake was also measured into a mutant with disrupted pma1 gene. This mutant did not form conidia. The mutant also exhibited uncoupler sensitivity of (14)C-valine uptake. These observations showed that a PMF must have been generated by a mechanism(s) other than the H(+)-ATPase activity in the WT before H(+)-ATPase expression and in mycelia with disrupted H(+)-ATPase.
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Affiliation(s)
- Martin Šimkovič
- Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237-Bratislava, Slovakia
| | - Petra Olejníková
- Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237-Bratislava, Slovakia
| | - Matej Mat'at'a
- Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237-Bratislava, Slovakia
| | - Peter Žemla
- Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237-Bratislava, Slovakia
| | - Viera Vilimová
- Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237-Bratislava, Slovakia
| | - Lenka Farkašová
- Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237-Bratislava, Slovakia
| | - L'udovít Varečka
- Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237-Bratislava, Slovakia
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85
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Lucena MN, Pinto MR, Garçon DP, McNamara JC, Leone FA. A kinetic characterization of the gill V(H+)-ATPase in juvenile and adult Macrobrachium amazonicum, a diadromous palaemonid shrimp. Comp Biochem Physiol B Biochem Mol Biol 2015; 181:15-25. [DOI: 10.1016/j.cbpb.2014.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/05/2014] [Accepted: 11/07/2014] [Indexed: 10/24/2022]
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86
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Abstract
Neutrophils are present within minutes to the site of aggression in the body making them one of the first cells of the immune system to be in contact with incoming threats. The cell functions of neutrophils are elicited through the engagement of surface receptors, some of which are located in a specific region of the membrane called lipid rafts, a functionally segregated region of the membrane enriched with cholesterol and distinct species of sphingomyelin and glycerophospholipids. Lipid rafts are relatively resistant to detergent extraction and this can be taken advantage of to isolate them from the rest of the cell membrane. This chapter will describe a reliable method to obtain lipid rafts from detergent-resistant membrane fractions of human neutrophils. Cells are lysed in an HEPES solution containing 0.5% Triton X-100, supernatants are mixed with a 42% sucrose solution, which is then overlaid with a 35% and 5% sucrose solution. The gradient is centrifuged for 16 h and the resulting fractions can be further analyzed by immunoblotting or subjected to immunoprecipitation.
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87
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Leone FA, Lucena MN, Rezende LA, Garçon DP, Pinto MR, Mantelatto FL, McNamara JC. A kinetic characterization of (Na+, K+)-ATPase activity in the gills of the pelagic seabob shrimp Xiphopenaeus kroyeri (Decapoda, Penaeidae). J Membr Biol 2014; 248:257-72. [PMID: 25534346 DOI: 10.1007/s00232-014-9765-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 12/04/2014] [Indexed: 10/24/2022]
Abstract
We characterize the kinetic properties of a gill (Na(+), K(+))-ATPase from the pelagic marine seabob Xiphopenaeus kroyeri. Sucrose density gradient centrifugation revealed membrane fractions distributed mainly into a heavy fraction showing considerable (Na(+), K(+))-ATPase activity, but also containing mitochondrial F0F1- and Na(+)- and V-ATPases. Western blot analysis identified a single immunoreactive band against the (Na(+), K(+))-ATPase α-subunit with an Mr of ≈ 110 kDa. The α-subunit was immunolocalized to the intralamellar septum of the gill lamellae. The (Na(+), K(+))-ATPase hydrolyzed ATP obeying Michaelis-Menten kinetics with VM = 109.5 ± 3.2 nmol Pi min(-1) mg(-1) and KM = 0.03 ± 0.003 mmol L(-1). Mg(2+) (VM = 109.8 ± 2.1 nmol Pi min(-1 )mg(-1), K0.5 = 0.60 ± 0.03 mmol L(-1)), Na(+) (VM = 117.6 ± 3.5 nmol Pi min(-1 ) mg(-1), K0.5 = 5.36 ± 0.14 mmol L(-1)), K(+) (VM = 112.9 ± 1.4 nmol Pi min(-1 )mg(-1), K0.5 = 1.32 ± 0.08 mmol L(-1)), and NH4 (+) (VM = 200.8 ± 7.1 nmol Pi min(-1 )mg(-1), K0.5 = 2.70 ± 0.04 mmol L(-1)) stimulated (Na(+), K(+))-ATPase activity following site-site interactions. K(+) plus NH4 (+) does not synergistically stimulate (Na(+), K(+))-ATPase activity, although each ion modulates affinity of the other. The enzyme exhibits a single site for K(+) binding that can be occupied by NH4 (+), stimulating the enzyme. Ouabain (KI = 84.0 ± 2.1 µmol L(-1)) and orthovanadate (KI = 0.157 ± 0.001 µmol L(-1)) inhibited total ATPase activity by ≈ 50 and ≈ 44 %, respectively. Ouabain inhibition increases ≈ 80 % in the presence of NH4 (+) with a threefold lower KI, suggesting that NH4 (+) is likely transported as a K(+) congener.
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Affiliation(s)
- Francisco Assis Leone
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto, SP, 14040-901, Brasil,
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88
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Kluth M, Stindt J, Dröge C, Linnemann D, Kubitz R, Schmitt L. A mutation within the extended X loop abolished substrate-induced ATPase activity of the human liver ATP-binding cassette (ABC) transporter MDR3. J Biol Chem 2014; 290:4896-4907. [PMID: 25533467 DOI: 10.1074/jbc.m114.588566] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The human multidrug resistance protein 3 (MDR3/ABCB4) belongs to the ubiquitous family of ATP-binding cassette (ABC) transporters and is located in the canalicular membrane of hepatocytes. There it flops the phospholipids of the phosphatidylcholine (PC) family from the inner to the outer leaflet. Here, we report the characterization of wild type MDR3 and the Q1174E mutant, which was identified previously in a patient with progressive familial intrahepatic cholestasis type 3 (PFIC-3). We expressed different variants of MDR3 in the yeast Pichia pastoris, purified the proteins via tandem affinity chromatography, and determined MDR3-specific ATPase activity in the presence or absence of phospholipids. The ATPase activity of wild type MDR3 was stimulated 2-fold by liver PC or 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine lipids. Furthermore, the cross-linking of MDR3 with a thiol-reactive fluorophore blocked ATP hydrolysis and exhibited no PC stimulation. Similarly, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin lipids did not induce an increase of wild type MDR3 ATPase activity. The phosphate analogues beryllium fluoride and aluminum fluoride led to complete inhibition of ATPase activity, whereas orthovanadate inhibited exclusively the PC-stimulated ATPase activity of MDR3. The Q1174E mutation is located in the nucleotide-binding domain in direct proximity of the leucine of the ABC signature motif and extended the X loop, which is found in ABC exporters. Our data on the Q1174E mutant demonstrated basal ATPase activity, but PC lipids were incapable of stimulating ATPase activity highlighting the role of the extended X loop in the cross-talk of the nucleotide-binding domain and the transmembrane domain.
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Affiliation(s)
- Marianne Kluth
- Institute of Biochemistry, Heinrich Heine University, 40225 Düsseldorf
| | - Jan Stindt
- Department of Gastroenterology, Hepatology and Infectiology, University Hospital, 40225 Düsseldorf
| | - Carola Dröge
- Department of Gastroenterology, Hepatology and Infectiology, University Hospital, 40225 Düsseldorf
| | - Doris Linnemann
- Department of Gastroenterology, Hepatology and Infectiology, University Hospital, 40225 Düsseldorf
| | - Ralf Kubitz
- Department of Gastroenterology, Hepatology and Infectiology, University Hospital, 40225 Düsseldorf
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University, 40225 Düsseldorf; Cluster of Excellence on Plant Sciences, Heinrich Heine University, 40225 Düsseldorf, Germany.
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89
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Clark O, Park I, Di Florio A, Cichon AC, Rustin S, Jugov R, Maeshima R, Stoker AW. Oxovanadium-based inhibitors can drive redox-sensitive cytotoxicity in neuroblastoma cells and synergise strongly with buthionine sulfoximine. Cancer Lett 2014; 357:316-327. [PMID: 25444896 DOI: 10.1016/j.canlet.2014.11.039] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 12/30/2022]
Abstract
In a wide range of neuroblastoma-derived lines oxovanadium compounds such as bis(maltolato)oxovanadium(IV) (BMOV) are cytotoxic. This is not explained by oxidative stress or inhibition of ion channels. Genotoxicity is unlikely given that a p53 response is absent and p53-mutant lines are also sensitive. Cytotoxicity is inhibited by N-acetyl cysteine and glutathione ester, indicating that BMOV action is sensitive to cytoplasmic redox and thiol status. Significantly, combining BMOV with glutathione synthesis inhibition greatly enhances BMOV-induced cell death. This combination treatment triggers high AKT pathway activation, highlighting the potential functional importance of PTP inhibition by BMOV. AKT activation itself, however, is not required for cytotoxicity. Oxovanadium compounds may thus represent novel leads as p53-independent therapeutics for neuroblastoma.
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Affiliation(s)
- Owen Clark
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Inhye Park
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Alessia Di Florio
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Ann-Christin Cichon
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Sarah Rustin
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Roman Jugov
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Ruhina Maeshima
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Andrew W Stoker
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK.
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90
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Mori MX, Inoue R. New experimental trends for phosphoinositides research on ion transporter/channel regulation. J Pharmacol Sci 2014; 126:186-97. [PMID: 25367262 DOI: 10.1254/jphs.14r14cp] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Phosphoinositides(4,5)-bisphosphates [PI(4,5)P2] critically controls membrane excitability, the disruption of which leads to pathophysiological states. PI(4,5)P2 plays a primary role in regulating the conduction and gating properties of ion channels/transporters, through electrostatic and hydrophobic interactions that allow direct associations. In recent years, the development of many molecular tools have brought deep insights into the mechanisms underlying PI(4,5)P2-mediated regulation. This review summarizes the methods currently available to manipulate the cell membrane PI(4,5)P2 level including pharmacological interventions as well as newly designed molecular tools. We concisely introduce materials and experimental designs suitable for the study of PI(4,5)P2-mediated regulation of ion-conducting molecules, in order to assist researchers who are interested in this area. It is our further hope that the knowledge introduced in this review will help to promote our understanding about the pathology of diseases such as cardiac arrhythmias, bipolar disorders, and Alzheimer's disease which are somehow associated with a disruption of PI(4,5)P2 metabolism.
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Affiliation(s)
- Masayuki X Mori
- Department of Synthetic Chemistry and Biological Chemistry, School of Engineering, Kyoto University, Japan
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91
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Žižić M, Živić M, Maksimović V, Stanić M, Križak S, Antić TC, Zakrzewska J. Vanadate influence on metabolism of sugar phosphates in fungus Phycomyces blakesleeanus. PLoS One 2014; 9:e102849. [PMID: 25036378 PMCID: PMC4103890 DOI: 10.1371/journal.pone.0102849] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/24/2014] [Indexed: 11/19/2022] Open
Abstract
The biological and chemical basis of vanadium action in fungi is relatively poorly understood. In the present study, we investigate the influence of vanadate (V5+) on phosphate metabolism of Phycomyces blakesleeanus. Addition of V5+ caused increase of sugar phosphates signal intensities in 31P NMR spectra in vivo. HPLC analysis of mycelial phosphate extracts demonstrated increased concentrations of glucose 6 phosphate, fructose 6 phosphate, fructose 1, 6 phosphate and glucose 1 phosphate after V5+ treatment. Influence of V5+ on the levels of fructose 2, 6 phosphate, glucosamine 6 phosphate and glucose 1, 6 phosphate (HPLC), and polyphosphates, UDPG and ATP (31P NMR) was also established. Increase of sugar phosphates content was not observed after addition of vanadyl (V4+), indicating that only vanadate influences its metabolism. Obtained results from in vivo experiments indicate catalytic/inhibitory vanadate action on enzymes involved in reactions of glycolysis and glycogenesis i.e., phosphoglucomutase, phosphofructokinase and glycogen phosphorylase in filamentous fungi.
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Affiliation(s)
- Milan Žižić
- Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Belgrade, Serbia
| | - Miroslav Živić
- University of Belgrade-Faculty of Biology, Department of Physiology and Biophysics, Belgrade, Serbia
| | - Vuk Maksimović
- Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Belgrade, Serbia
| | - Marina Stanić
- Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Belgrade, Serbia
| | - Strahinja Križak
- Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Belgrade, Serbia
| | - Tijana Cvetić Antić
- University of Belgrade-Faculty of Biology, Department of Physiology and Biophysics, Belgrade, Serbia
| | - Joanna Zakrzewska
- Institute of General and Physical Chemistry, NMR Laboratory, Belgrade, Serbia
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92
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Liu Y, Zhang Z, Zhao X, Yu R, Zhang X, Wu S, Liu J, Chi X, Song X, Fu L, Yu Y, Hou L, Chen W. Enterovirus 71 inhibits cellular type I interferon signaling by downregulating JAK1 protein expression. Viral Immunol 2014; 27:267-76. [PMID: 24905060 DOI: 10.1089/vim.2013.0127] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Enterovirus 71 (EV71) infection can cause severe disease and lead to death in children. Recurring outbreaks of EV71 have been reported in several countries. Interferons (IFNs) have been used for decades to treat several types of viral infection, but have a limited ability to inhibit EV71 replication. Herein, we intend to investigate the mechanisms by which EV71 inhibits the cellular type I IFN response. In this study, MRC-5 (human embryonic lung fibroblast) or RD (human rhabdomyosarcoma) cells were infected with EV71, and then treated with or without IFN-α2b. Cells were harvested and analyzed by flow cytometry to determine the level of IFNAR1. Cell lysis were prepared to detect the levels of STAT1, STAT2, phosphorylated STAT1, phosphorylated STAT2, IFNAR1, JAK1, and TYK2 by Western blotting. The phosphorylation of STAT1 and STAT2 induced by IFN were inhibited without significant downregulation of IFNAR1 in EV71-infected cells. The EV71-induced suppression of STAT1 and STAT2 phosphorylation was not rescued by the protein tyrosine phosphatases inhibitor, and was independent of suppressor of cytokine signaling protein 1/3 levels. The phosphorylation of JAK1 and TYK2 were inhibited accompanied by EV71-induced downregulation of JAK1, which occurred at a post-transcriptional level and was proteasome independent. JAK1 expression did not decrease, and IFN-α-stimulated STAT1 and STAT2 phosphorylation were not blocked in HEK293T cells overexpressing the EV71 viral protein 2A or 3C. This study demonstrates that EV71 inhibits the cellular type I IFN antiviral pathway by downregulating JAK1, while the expression of IFNAR1 does not significantly alter in EV71-infected cells. Additionally, the EV71 viral proteins 2A and 3C do not act as antagonists of cellular type I IFN signaling.
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93
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Abstract
SIGNIFICANCE Protein tyrosine phosphatases (PTPs) are important enzymes that are involved in the regulation of cellular signaling. Evidence accumulated over the years has indicated that PTPs present exciting opportunities for drug discovery against diseases such as diabetes, cancer, autoimmune diseases, and tuberculosis. However, the highly conserved and partially positive charge of the catalytic sites of PTPs is a major challenge in the development of potent and highly selective PTP inhibitors. RECENT ADVANCES Here, we examine the strategy of developing bidentate inhibitors for selective inhibition of PTPs. Bidentate inhibitors are small-molecular-weight compounds with the ability to bind to both the active site and a non-conserved secondary phosphate binding site. This secondary phosphate binding site was initially discovered in protein tyrosine phosphatase 1B (PTP1B), and, hence, most of the bidentate inhibitors reported in this review are PTP1B inhibitors. CRITICAL ISSUES Although bidentate inhibition is a good strategy for developing potent and selective inhibitors, the cell membrane permeability and pharmacokinetic properties of the inhibitors are also important for successful drug development. In this review, we will also summarize the various efforts made toward the development of phosphotyrosine (pTyr) mimetics for increasing cellular permeability. FUTURE DIRECTIONS Even though the secondary phosphate binding site was initially found in PTP1B, structural data have shown that a secondary binding site can also be found in other PTPs, albeit with varying degrees of accessibility. Along with improvements in pTyr mimetics, we believe that the future will see an increase in the number of orally bioavailable bidentate inhibitors against the various classes of PTPs.
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Affiliation(s)
- Joo-Leng Low
- 1 Institute of Chemical and Engineering Sciences , Agency for Science Technology and Research, Singapore, Singapore
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94
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Wyatt LA, Filbin MT, Keirstead HS. PTEN inhibition enhances neurite outgrowth in human embryonic stem cell-derived neuronal progenitor cells. J Comp Neurol 2014; 522:2741-55. [PMID: 24610700 DOI: 10.1002/cne.23580] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/29/2013] [Accepted: 10/07/2013] [Indexed: 12/27/2022]
Abstract
We investigated the role of PTEN (phosphatase and tensin homolog deleted on chromosome 10) during neurite outgrowth of human embryonic stem cell (hESC)-derived neuronal progenitors. PTEN inhibits phosphoinositide 3-kinase (PI3K)/Akt signaling, a common and central outgrowth and survival pathway downstream of neuronal growth factors. It is known that PTEN inhibition, by either polymorphic mutation or gene deletion, can lead to the development of tumorigenesis (Stambolic et al., ; Tamura et al., ). However, temporary inhibition of PTEN, through pharmacological manipulation, could regulate signaling events such as the PI3K/Akt signaling pathway, leading to enhanced recovery of central nervous system (CNS) injury and disease. We demonstrate that pharmacological inhibition of PTEN in hESC-derived neuronal progenitors significantly increased neurite outgrowth in vitro in a dose- and time-dependent manner. Our results indicate that inhibition of PTEN augments neurite outgrowth beyond that of traditional methods such as elevation of intracellular cyclic adenosine monophosphate (cAMP) levels, and depends on upregulation of the PI3K/Akt signaling pathway and its downstream effectors, such as mammalian target of rapamycin (mTOR). PTEN inhibition also rescued neurite outgrowth over an inhibitory substrate in vitro. These findings indicate a remarkable impact on hESC-derived neuronal progenitor plasticity through PTEN inhibition. Overall, these findings identify a novel therapeutic strategy for neurite outgrowth in CNS injury and disease.
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Affiliation(s)
- Lindsey A Wyatt
- Department of Anatomy and Neurobiology, Sue and Bill Gross Stem Cell Research Center, Reeve-Irvine Research Center, School of Medicine, University of California at Irvine, Irvine, California, 92697-4292
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95
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Akiba H, Sumaoka J, Hamakubo T, Komiyama M. Conjugation-free, visual, and quantitative evaluation of inhibitors on protein tyrosine kinases and phosphatases with a luminescent Tb(III) complex. Anal Bioanal Chem 2014; 406:2957-64. [PMID: 24652149 DOI: 10.1007/s00216-014-7707-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/14/2014] [Accepted: 02/19/2014] [Indexed: 10/25/2022]
Abstract
A straightforward and visual method to assess inhibitors on protein tyrosine kinases (PTKs) and phosphatases (PTPs) has been developed. These enzymes play critical roles in a number of diseases and, thus, their inhibitors are important for effective therapy. With the use of the long-life luminescence emitted from a binuclear Tb(III) complex, enzymatic reactions of PTKs and PTPs were monitored in real-time, and the inhibitor activity was quantitatively evaluated in terms of the decrease in the rate of luminescence change. No conjugation of the probe to a substrate peptide was necessary. The IC50 values of four inhibitors on three kinds of PTKs [Src, Fyn, and epidermal growth factor receptor (EGFR)] were determined. For example, gefitinib, which is a selective inhibitor on EGFR, inhibited this PTK with IC50 of 22 nM. Towards Src and Fyn (non-targeted PTK), however, IC50 of this inhibitor was greater than 20 μM as expected. Inhibition of two kinds of PTPs (Shp-1 and PTP1B) by two inhibitors was also assayed, providing completely consistent results on their known selectivity. Furthermore, the system where both PTK and PTP are active was monitored and the reactions were visualized with the present Tb(III) complex-based method. High potential of the present method to a variety of systems has been evidenced.
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Affiliation(s)
- Hiroki Akiba
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Meguro-ku, Tokyo, 153-8904, Japan
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96
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Linford AS, Jiang NM, Edwards TE, Sherman NE, Van Voorhis WC, Stewart LJ, Myler PJ, Staker BL, Petri WA. Crystal structure and putative substrate identification for the Entamoeba histolytica low molecular weight tyrosine phosphatase. Mol Biochem Parasitol 2014; 193:33-44. [PMID: 24548880 DOI: 10.1016/j.molbiopara.2014.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 01/12/2014] [Accepted: 01/22/2014] [Indexed: 11/28/2022]
Abstract
Entamoeba histolytica is a eukaryotic intestinal parasite of humans, and is endemic in developing countries. We have characterized the E. histolytica putative low molecular weight protein tyrosine phosphatase (LMW-PTP). The structure for this amebic tyrosine phosphatase was solved, showing the ligand-induced conformational changes necessary for binding of substrate. In amebae, it was expressed at low but detectable levels as detected by immunoprecipitation followed by immunoblotting. A mutant LMW-PTP protein in which the catalytic cysteine in the active site was replaced with a serine lacked phosphatase activity, and was used to identify a number of trapped putative substrate proteins via mass spectrometry analysis. Seven of these putative substrate protein genes were cloned with an epitope tag and overexpressed in amebae. Five of these seven putative substrate proteins were demonstrated to interact specifically with the mutant LMW-PTP. This is the first biochemical study of a small tyrosine phosphatase in Entamoeba, and sets the stage for understanding its role in amebic biology and pathogenesis.
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Affiliation(s)
- Alicia S Linford
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA.
| | - Nona M Jiang
- Division of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Thomas E Edwards
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA; Emerald Bio, Bainbridge Island, WA 98110, USA
| | - Nicholas E Sherman
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Wesley C Van Voorhis
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA; Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Lance J Stewart
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA; Emerald Bio, Bainbridge Island, WA 98110, USA
| | - Peter J Myler
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA; Seattle Biomedical Research Institute, Seattle, WA 98109, USA; Departments of Global Health and Medical Education & Biomedical Informatics, University of Washington, Seattle, WA 98195, USA
| | - Bart L Staker
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA; Emerald Bio, Bainbridge Island, WA 98110, USA
| | - William A Petri
- Division of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, VA 22908, USA; Department of Medicine, University of Virginia, Charlottesville, VA 22908, USA; Department of Pathology, University of Virginia, Charlottesville, VA 22908, USA.
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97
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Ruberto I, Szoor B, Clark R, Matthews KR. Investigating mammalian tyrosine phosphatase inhibitors as potential 'piggyback' leads to target Trypanosoma brucei transmission. Chem Biol Drug Des 2014; 81:291-301. [PMID: 23066974 DOI: 10.1111/cbdd.12079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
African trypanosomiasis is a neglected tropical disease affecting humans and animals across 36 sub-Saharan African countries. We have investigated the potential to exploit a 'piggyback' approach to inhibit Trypanosoma brucei transmission by targeting the key developmental regulator of transmission, T. brucei protein tyrosine phosphatase 1. This strategy took advantage of the extensive investment in inhibitors for human protein tyrosine phosphatase 1B, a key target for pharmaceutical companies for the treatment of obesity and diabetes. Structural predictions for human and trypanosome tyrosine phosphatases revealed the overall conservation of important functional motifs, validating the potential for exploiting cross specific compounds. Thereafter, nineteen inhibitors were evaluated; seventeen from a protein tyrosine phosphatase 1B-targeted inhibitor library and two from literature analysis - oleanolic acid and suramin, the latter of which is a front line drug against African trypanosomiasis. The compounds tested displayed similar inhibitory activities against the human and trypanosome enzymes, mostly behaving as noncompetitive inhibitors. However, their activity against T. brucei in culture was low, necessitating further chemical modification to improve their efficacy and specificity. Nonetheless, the results validate the potential to explore a 'piggyback' strategy targeting T. brucei protein tyrosine phosphatase 1 through exploiting the large pharmacological investment in therapies for obesity targeting protein tyrosine phosphatase 1B.
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Affiliation(s)
- Irene Ruberto
- Centre for Immunity, Infection and Evolution, School of Biological Sciences, Institute of Immunology and Infection Research, University of Edinburgh, King's Building, West Mains Road, Edinburgh EH9 3JT, UK
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98
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Schoof EM, Linding R. Experimental and computational tools for analysis of signaling networks in primary cells. ACTA ACUST UNITED AC 2014; 104:11.11.1-11.11.23. [PMID: 24510617 DOI: 10.1002/0471142735.im1111s104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cellular information processing in signaling networks forms the basis of responses to environmental stimuli. At any given time, cells receive multiple simultaneous input cues, which are processed and integrated to determine cellular responses such as migration, proliferation, apoptosis, or differentiation. Protein phosphorylation events play a major role in this process and are often involved in fundamental biological and cellular processes such as protein-protein interactions, enzyme activity, and immune responses. Determining which kinases phosphorylate specific phospho sites poses a challenge; this information is critical when trying to elucidate key proteins involved in specific cellular responses. Here, methods to generate high-quality quantitative phosphorylation data from cell lysates originating from primary cells, and how to analyze the generated data to construct quantitative signaling network models, are presented. These models can subsequently be used to guide follow-up in vitro/in vivo validation studies.
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Affiliation(s)
- Erwin M Schoof
- Cellular Signal Integration Group (C-SIG), Center for Biological Sequence Analysis (CBS), Department of Systems Biology, Technical University of Denmark (DTU), Lyngby, Denmark
| | - Rune Linding
- Cellular Signal Integration Group (C-SIG), Center for Biological Sequence Analysis (CBS), Department of Systems Biology, Technical University of Denmark (DTU), Lyngby, Denmark
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99
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Ouderkirk JL, Krendel M. Myosin 1e is a component of the invadosome core that contributes to regulation of invadosome dynamics. Exp Cell Res 2014; 322:265-76. [PMID: 24462457 DOI: 10.1016/j.yexcr.2014.01.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 01/09/2014] [Accepted: 01/15/2014] [Indexed: 01/07/2023]
Abstract
Myosin 1e (myo1e) is an actin-based motor protein that has been implicated in cell adhesion and migration. We examined the role of myo1e in invadosomes, actin-rich adhesion structures that are important for degradation and invasion of the extracellular matrix. RSV-transformed BHK-21 cells, which readily form invadosomes and invadosome rosettes, were used as the experimental model. Myo1e localization to the actin-rich core of invadosomes required the proline-rich Tail Homology 2 (TH2) domain. During invadosome rosette expansion, we observed myo1e recruitment to newly forming invadosomes via Tail Homology 1 (TH1)-dependent interactions with the plasma membrane, where it preceded actin and paxillin. Dominant-negative inhibition of myo1e resulted in mislocalized invadosome formation, usually at the center of the rosette. We propose that TH2 domain of myo1e provides the key signal for localization to invadosomes, while TH1 domain interactions facilitate myo1e targeting to the plasma membrane-proximal locations within the rosettes. Myo1e may then act as a scaffold, linking the plasma membrane with the actin cytoskeleton and helping direct new invadosome formation to the periphery of the rosette.
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Affiliation(s)
- Jessica L Ouderkirk
- Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY 13210, United States
| | - Mira Krendel
- Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY 13210, United States.
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100
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Yang XG, Wang K. Chemical, biochemical, and biological behaviors of vanadate and its oligomers. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2014; 54:1-18. [PMID: 24420708 DOI: 10.1007/978-3-642-41004-8_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Vanadate is widely used as an inhibitor of protein tyrosine phosphatases (PTPase) and is routinely applied in cell lysis buffers or immunoprecipitations of phosphotyrosyl proteins. Additionally, vanadate has been extensively studied for its antidiabetic and anticancer effects. In most studies, orthovanadate or metavanadate was used as the starting compound, whereas these "vanadate" solutions may contain more or less oligomerized species. Whether and how different species of vanadium compounds formed in the biological media exert specific biological effect is still a mystery. In the present commentary, we focus on the chemical, biochemical, and biological behaviors of vanadate. On the basis of species formation of vanadate in chemical and biological systems, we compared the biological effects and working mechanism of monovanadate with that of its oligomers, especially the decamer. We propose that different oligomers may exert a specific biological effect, which depends on their structures and the context of the cell types, by different modes of action.
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Affiliation(s)
- Xiao-Gai Yang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, People's Republic of China
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