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Guilbert C, Chayer B, Allard L, Yu FTH, Cloutier G. Influence of erythrocyte aggregation on radial migration of platelet-sized spherical particles in shear flow. J Biomech 2017; 61:26-33. [PMID: 28720200 DOI: 10.1016/j.jbiomech.2017.06.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 06/20/2017] [Accepted: 06/29/2017] [Indexed: 11/19/2022]
Abstract
Blood platelets when activated are involved in the mechanisms of hemostasis and thrombosis, and their migration toward injured vascular endothelium necessitates interaction with red blood cells (RBCs). Rheology co-factors such as a high hematocrit and a high shear rate are known to promote platelet mass transport toward the vessel wall. Hemodynamic conditions promoting RBC aggregation may also favor platelet migration, particularly in the venous system at low shear rates. The aim of this study was to confirm experimentally the impact of RBC aggregation on platelet-sized micro particle migration in a Couette flow apparatus. Biotin coated micro particles were mixed with saline or blood with different aggregation tendencies, at two shear rates of 2 and 10s-1 and three hematocrits ranging from 20 to 60%. Streptavidin membranes were respectively positioned on the Couette static and rotating cylinders upon which the number of adhered fluorescent particles was quantified. The platelet-sized particle adhesion on both walls was progressively enhanced by increasing the hematocrit (p<0.001), reducing the shear rate (p<0.001), and rising the aggregation of RBCs (p<0.001). Particle count was minimum on the stationary cylinder when suspended in saline at 2s-1 (57±33), and maximum on the rotating cylinder at 60% hematocrit, 2s-1 and the maximum dextran-induced RBC aggregation (2840±152). This fundamental study is confirming recent hypotheses on the role of RBC aggregation on venous thrombosis, and may guide molecular imaging protocols requiring injecting active labeled micro particles in the venous flow system to probe human diseases.
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Affiliation(s)
- Cyrille Guilbert
- Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center (CRCHUM), Montréal, Québec, Canada
| | - Boris Chayer
- Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center (CRCHUM), Montréal, Québec, Canada
| | - Louise Allard
- Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center (CRCHUM), Montréal, Québec, Canada
| | - François T H Yu
- Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center (CRCHUM), Montréal, Québec, Canada
| | - Guy Cloutier
- Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center (CRCHUM), Montréal, Québec, Canada; Institute of Biomedical Engineering, University of Montreal, Montréal, Québec, Canada; Department of Radiology, Radio-oncology and Nuclear Medicine, University of Montreal, Montréal, Québec, Canada.
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2
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Lee JY, Kim DG, Kim BG, Yang WS, Hong J, Kang T, Oh YS, Kim KR, Han BW, Hwang BJ, Kang BS, Kang MS, Kim MH, Kwon NH, Kim S. Promiscuous methionyl-tRNA synthetase mediates adaptive mistranslation to protect cells against oxidative stress. J Cell Sci 2014; 127:4234-45. [PMID: 25097229 PMCID: PMC4179492 DOI: 10.1242/jcs.152470] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) acylate transfer (t)RNAs with amino acids. Charging tRNAs with the right amino acids is the first step in translation; therefore, the accurate and error-free functioning of ARSs is an essential prerequisite for translational fidelity. A recent study found that methionine (Met) can be incorporated into non-Met residues of proteins through methionylation of non-cognate tRNAs under conditions of oxidative stress. However, it was not understood how this mis-methionylation is achieved. Here, we report that methionyl-tRNA synthetase (MRS) is phosphorylated at Ser209 and Ser825 by extracellular signal-related kinase (ERK1/2) under conditions of stress caused by reactive oxygen species (ROS), and that this phosphorylated MRS shows increased affinity for non-cognate tRNAs with lower affinity for tRNAMet, leading to an increase in Met residues in cellular proteins. The expression of a mutant MRS containing the substitutions S209D and S825D, mimicking dual phosphorylation, reduced ROS levels and cell death. This controlled inaccuracy of MRS seems to serve as a defense mechanism against ROS-mediated damage at the cost of translational fidelity.
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Affiliation(s)
- Jin Young Lee
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Dae Gyu Kim
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Byung-Gyu Kim
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Won Suk Yang
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Jeena Hong
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Taehee Kang
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Young Sun Oh
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Kyung Rok Kim
- Research Institute of Pharmaceutical Sciences, Department of Pharmacy, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Byung Woo Han
- Research Institute of Pharmaceutical Sciences, Department of Pharmacy, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Byung Joon Hwang
- Department of Molecular Bioscience, Kang Won National University, Chuncheon-si, Gangwon-do 200-701, Korea
| | - Beom Sik Kang
- School of Life Science and Biotechnology, Kyungpook National University, Daegu 702-701, Korea
| | - Mi-Sun Kang
- Department of Computer Science and Engineering Center for Computer Graphics and Virtual Reality, Ewha Womans University, Seoul 120-750, Korea
| | - Myung-Hee Kim
- Department of Computer Science and Engineering Center for Computer Graphics and Virtual Reality, Ewha Womans University, Seoul 120-750, Korea
| | - Nam Hoon Kwon
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Sunghoon Kim
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea WCU Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Suwon 443-270, Korea
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Abstract
BACKGROUND Homogeneous time-resolved fluorescence (HTRF) is a fluorescence resonance energy transfer-based technology used to measure bimolecular interactions. It has been applied successfully to kinase assays and has become an important tool in kinase drug discovery. OBJECTIVE This article reviews the current status of HTRF technology in biochemical and cellular kinase assays. METHODS Recent literature and meeting reports on HTRF kinase assays are reviewed, and their principles, advantages and drawbacks, current status and the potential applications in kinase drug discovery are discussed. RESULTS/CONCLUSION HTRF kinase assays are homogeneous, robust, sensitive, easy to miniaturize and high-throughput. This assay format is versatile, as both peptide and protein substrates can be used, and high ATP concentrations are tolerated, which enables the assay to be performed under conditions mimicking the physiological environment. HTRF kinase assays have been applied to both high-throughput screening and compound mechanistic studies. Besides protein kinases, the technology has now been expanded into the lipid kinase family. Furthermore, the utility of HTRF technology in cellular assays is emerging. HTRF kinase assays are a great addition to the toolbox for kinase drug discovery.
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Affiliation(s)
- Yong Jia
- Group Leader Genomics Institute of the Novartis Research Foundation, Department of Kinase Biology, 10675 John J Hopkins Dr, San Diego, CA 92121, USA +858 812 1728 ; +858 812 1918 ;
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4
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Identification and characterization of a leucine-rich repeat kinase 2 (LRRK2) consensus phosphorylation motif. PLoS One 2010; 5:e13672. [PMID: 21060682 PMCID: PMC2965117 DOI: 10.1371/journal.pone.0013672] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 10/05/2010] [Indexed: 01/01/2023] Open
Abstract
Mutations in LRRK2 (leucine-rich repeat kinase 2) have been identified as major genetic determinants of Parkinson's disease (PD). The most prevalent mutation, G2019S, increases LRRK2's kinase activity, therefore understanding the sites and substrates that LRRK2 phosphorylates is critical to understanding its role in disease aetiology. Since the physiological substrates of this kinase are unknown, we set out to reveal potential targets of LRRK2 G2019S by identifying its favored phosphorylation motif. A non-biased screen of an oriented peptide library elucidated F/Y-x-T-x-R/K as the core dependent substrate sequence. Bioinformatic analysis of the consensus phosphorylation motif identified several novel candidate substrates that potentially function in neuronal pathophysiology. Peptides corresponding to the most PD relevant proteins were efficiently phosphorylated by LRRK2 in vitro. Interestingly, the phosphomotif was also identified within LRRK2 itself. Autophosphorylation was detected by mass spectrometry and biochemical means at the only F-x-T-x-R site (Thr 1410) within LRRK2. The relevance of this site was assessed by measuring effects of mutations on autophosphorylation, kinase activity, GTP binding, GTP hydrolysis, and LRRK2 multimerization. These studies indicate that modification of Thr1410 subtly regulates GTP hydrolysis by LRRK2, but with minimal effects on other parameters measured. Together the identification of LRRK2's phosphorylation consensus motif, and the functional consequences of its phosphorylation, provide insights into downstream LRRK2-signaling pathways.
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5
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Jia Y, Gu XJ, Brinker A, Warmuth M. Measuring the tyrosine kinase activity: a review of biochemical and cellular assay technologies. Expert Opin Drug Discov 2008; 3:959-78. [DOI: 10.1517/17460441.3.8.959] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Yong Jia
- Group Leader Genomics Institute of the Novartis Research Foundation, Department of Kinase Biology, 10675 John J. Hopkins Dr, San Diego, CA 92121, USA ;
| | - Xiang-ju Gu
- Group Leader Genomics Institute of the Novartis Research Foundation, Department of Lead Discovery, 10675 John J. Hopkins Dr, San Diego, CA 92121, USA
| | - Achim Brinker
- Associate Director Genomics Institute of the Novartis Research Foundation, Department of Lead Discovery, 10675 John J. Hopkins Dr, San Diego, CA 92121, USA
| | - Markus Warmuth
- Director Genomics Institute of the Novartis Research Foundation, Department of Kinase Biology, 10675 John J. Hopkins Dr, San Diego, CA 92121, USA
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Wu D, Nair-Gill E, Sher DA, Parker LL, Campbell JM, Siddiqui M, Stock W, Kron SJ. Assaying Bcr-Abl kinase activity and inhibition in whole cell extracts by phosphorylation of substrates immobilized on agarose beads. Anal Biochem 2005; 347:67-76. [PMID: 16236241 PMCID: PMC4562293 DOI: 10.1016/j.ab.2005.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Revised: 08/17/2005] [Accepted: 09/03/2005] [Indexed: 11/21/2022]
Abstract
There is a current and increasing demand for simple, robust, nonradioactive assays of protein tyrosine kinase activity with applications for clinical diagnosis and high-throughput screening of potential molecularly targeted therapeutic agents. One significant challenge is to detect and measure the activity of specific kinases with key roles in cell signaling as an approach to distinguish normal cells from cancer cells and as a means of evaluating targeted drug efficacy and resistance in cancer cells. Here, we describe a method in which kinase substrates fused to glutathione-S-transferase and immobilized on glutathione agarose beads are phosphorylated, eluted, and then assayed to detect kinase activity. The activity of recombinant, purified c-Abl kinase or Bcr-Abl kinase in whole cell extracts can be detected with equivalent specificity, sensitivity, and reproducibility. Similarly, inhibition of recombinant c-Abl or Bcr-Abl in cells or cell extracts by imatinib mesylate and other Bcr-Abl targeted kinase inhibitors is readily assayed. This simple kinase assay is sufficiently straightforward and robust for use in clinical laboratories and is potentially adaptable to high-throughput assay formats.
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Affiliation(s)
- Ding Wu
- Center for Molecular Oncology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Evan Nair-Gill
- Center for Molecular Oncology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Dorie A. Sher
- Department of Medicine and Cancer Research Center, University of Chicago, Chicago, IL 60637, USA
| | - Laurie L. Parker
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Jennifer M. Campbell
- Center for Molecular Oncology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Mariah Siddiqui
- Department of Medicine and Cancer Research Center, University of Chicago, Chicago, IL 60637, USA
| | - Wendy Stock
- Department of Medicine and Cancer Research Center, University of Chicago, Chicago, IL 60637, USA
| | - Stephen J. Kron
- Center for Molecular Oncology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
- Corresponding author. Fax: +1 773 702 4394
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7
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Ahmed S, Shibazaki M, Takeuchi T, Kikuchi H. Protein kinase C? activity is involved in the 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced signal transduction pathway leading to apoptosis in L-MAT, a human lymphoblastic T-cell line. FEBS J 2005; 272:903-15. [PMID: 15691325 DOI: 10.1111/j.1742-4658.2004.04519.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The aromatic hydrocarbon receptor (AhR)-dependent pathway involved in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity has been studied extensively, but the AhR-independent molecular mechanism has not. In previous studies we found that the AhR is not expressed in L-MAT, a human lymphoblastic T-cell line. In this report, we provide the following evidence that the protein kinase C (PKC)theta activity is functionally involved in the AhR-independent signal transduction mechanism that participates in the TCDD-induced L-MAT cell apoptosis. First, only rottlerin, a novel PKC (nPKC)-selective inhibitor, blocked the apoptosis completely, in a dose-dependent manner. Second, PKCtheta was the major nPKC isoform (compared to PKCdelta) expressed in the L-MAT cell line. Third, a cell-permeable myristoylated PKCtheta pseudosubstrate peptide inhibitor also blocked the apoptosis completely, in a dose-dependent manner. Fourth, both rottlerin and myristoylated PKCtheta pseudosubstrate peptide inhibitor completely inhibited PKCtheta kinase activity in vitro at doses that effectively blocked TCDD-induced L-MAT cell apoptosis. TCDD treatment induced a time-dependent activation of nPKC kinase activity in L-MAT cells, and moreover, TCDD induced a translocation of PKCtheta from the cytosolic fraction to the particulate fraction in L-MAT cells. Finally, transient over-expression of a dominant negative PKCtheta (a kinase-dead mutant, K/R 409) in L-MAT cells conferred significant protection against TCDD-induced apoptosis.
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Affiliation(s)
- Sohel Ahmed
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
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8
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Liu Y, Li R, Ladisch S. Exogenous Ganglioside GD1a Enhances Epidermal Growth Factor Receptor Binding and Dimerization. J Biol Chem 2004; 279:36481-9. [PMID: 15215248 DOI: 10.1074/jbc.m402880200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gangliosides are shed by tumor cells and can bind to normal cells in the tumor microenvironment and affect their function. Exposure of fibroblasts to exogenous gangliosides increases epidermal growth factor (EGF)-induced fibroblast proliferation and enhances EGF receptor (EGFR)-mediated activation of the mitogen-activated protein kinase signaling pathway (Li, R., Liu, Y., and Ladisch, S. (2001) J. Biol. Chem. 276, 42782-42792). Here we report that the EGFR itself is the target of this ganglioside effect: Preincubation of normal human dermal fibroblasts with G(D1a) ganglioside enhanced both EGF-induced EGFR autophosphorylation and receptor-tyrosine kinase activity. The enhancement was rapid (within 30 min), not due to alteration of time kinetics of the EGFR response to EGF, and reproduced in purified G(D1a)-enriched cell membranes isolated from ganglioside-preincubated fibroblasts. Evaluating the initial steps underlying activation, EGF binding, and EGFR dimerization, we found that G(D1a) enrichment of the cell membrane increased EGFR dimerization and the effective number of high affinity EGFR without increasing total receptor protein. Unexpectedly, G(D1a) enrichment also triggered increased EGFR dimerization in the absence of growth factor. This resulted in enhanced activation of the EGFR signal transduction cascade when EGF was added. We conclude that membrane ganglioside enrichment of normal fibroblasts (such as by tumor cell ganglioside shedding) facilitates receptor-receptor interactions (possibly by altering membrane topology), causing ligand-independent EGFR dimerization and, in turn, enhanced EGF signaling.
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Affiliation(s)
- Yihui Liu
- Glycobiology Program, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, D. C. 20010, USA
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9
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Lee SJ, Yoo HJ, Bae YS, Kim HJ, Lee ST. TIMP-1 inhibits apoptosis in breast carcinoma cells via a pathway involving pertussis toxin-sensitive G protein and c-Src. Biochem Biophys Res Commun 2004; 312:1196-201. [PMID: 14652000 DOI: 10.1016/j.bbrc.2003.11.050] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In addition to inhibiting matrix metalloproteinases, tissue inhibitor of metalloproteinase-1 (TIMP-1) is involved in the regulation of cell growth and survival. To determine its mechanism of action, we investigated effects of TIMP-1 on cell proliferation and survival and signaling pathways induced by TIMP-1 in the human breast carcinoma T-47D cell line. Treatment of T-47D cells with TIMP-1 strongly inhibited apoptosis induced by serum deprivation, but did not affect cell proliferation. TIMP-1 induced phosphorylation of Akt and extracellular signal-regulated protein kinases (ERKs), but pertussis toxin and specific inhibitors of Src family tyrosine kinases, protein tyrosine kinases, and phosphatidylinositol-3 kinase (PI3 kinase) blocked the ability of TIMP-1 to activate Akt and ERKs as well as the anti-apoptotic effect of TIMP-1. We found that TIMP-1 enhanced the kinase activities of c-Src and PI3 kinase and that this enhancement was inhibited by pertussis toxin. Inhibition of ERK activation, however, resulted in a slight decrease of the TIMP-1-induced anti-apoptotic effect. These findings demonstrate that the ability of TIMP-1 to inhibit apoptosis in T-47D cells is mediated by the sequential activation of pertussis toxin-sensitive G protein, c-Src, PI3 kinase, and Akt.
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Affiliation(s)
- Seo-Jin Lee
- Department of Biochemistry, College of Science, and Protein Network Research Center, Yonsei University, Seoul, Republic of Korea
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10
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Wichmann C, Naumann PT, Spangenberg O, Konrad M, Mayer F, Hoppert M. Liposomes for microcompartmentation of enzymes and their influence on catalytic activity. Biochem Biophys Res Commun 2003; 310:1104-10. [PMID: 14559229 DOI: 10.1016/j.bbrc.2003.09.128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Modular systems for protein coupling have been applied for anchoring enzyme molecules on liposome surfaces. Two cytoplasmic model enzymes, alpha-amylase from Escherichia coli (EC. 3.2.1.1) and guanylate kinase from Saccharomyces cerevisiae (EC. 2.7.4.8), were directly coupled by a histidine-tag or indirectly via strep-tag and streptavidin or streptactin linker to a liposome membrane. Though the catalytic properties of the enzymes are generally maintained, stability and specific activity of the enzymes are modified after coupling and are especially influenced by the lipid used for the liposome assembly.
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Affiliation(s)
- C Wichmann
- Institut für Mikrobiologie und Genetik der Universität Göttingen, Grisebachstrasse 8, 37077 Göttingen, Germany
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Asensio CJA, Garcia RC. Determination of a large number of kinase activities using peptide substrates, P81 phosphocellulose paper arrays and phosphor imaging. Anal Biochem 2003; 319:21-33. [PMID: 12842103 DOI: 10.1016/s0003-2697(03)00282-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To perform phosphoproteomics and signal transduction studies, a number of protein kinase activities and levels must be simultaneously analyzed in different cell samples and correlated with phosphoprotein patterns to obtain conclusions with regard to the regulation of kinase networks. We describe here a miniaturized format of the classical phosphocellulose (P81) paper binding assay with which up to 594 kinase reactions can be simultaneously analyzed. Kinase peptide substrates possessing a minimum of three consecutive basic residues were subjected to phosphorylation in 96-well plates and aliquots of the phosphorylation reactions were spotted on arrays printed on P81 papers. Phosphorylation levels were quantified using a storage phosphor system imager. The versatility of the procedure was validated by analyzing casein kinase 2, protein kinase C, and p34cdc2/cyclin B in cell extracts and testing the effect of known inhibitors and activators on kinase activities. This improved, miniaturized version of the classical P81 paper method combines simplicity, high sensitivity, high reproducibility, high reliability, and optimal Z factors and takes into account possible sources of background signals. We discuss the possibility of automation and the advantages over other methods.
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Affiliation(s)
- Cristian J A Asensio
- Leukocyte Biology Unit, International Centre for Genetic Engineering and Biotechnology, Area Science Park, 34012 Trieste, Italy
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12
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Gaudet EA, Huang KS, Zhang Y, Huang W, Mark D, Sportsman JR. A homogeneous fluorescence polarization assay adaptable for a range of protein serine/threonine and tyrosine kinases. JOURNAL OF BIOMOLECULAR SCREENING 2003; 8:164-75. [PMID: 12844437 DOI: 10.1177/1087057103252309] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recently, a new technology for high-throughput screening has been developed, called IMAP(patent pending). IMAP technology has previously been implemented in an assay for cyclic nucleotide phosphodiesterases (PDE). The authors describe the development of a homogeneous, non-antibody-based fluorescence polarization (FP) assay for a variety of protein kinases. In this assay, fluorescently labeled peptide substrate phosphorylated by the kinase is captured on modified nanoparticles through interactions with immobilized metal (M(III)) coordination complexes, resulting in a change from low to high polarization values. This assay is applicable to protein kinases that phosphorylate serine, threonine, or tyrosine residues. The IMAP platform is very compatible with high-throughput robotics and can be applied to the 1536-well format. As there are hundreds of different kinases coded for in the human genome, the assay platform described in this report is a valuable new tool in drug discovery.
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Affiliation(s)
- Elizabeth A Gaudet
- Molecular Devices Corporation, 1311 Orleans Ave. Sunnydale, CA 94089, USA.
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Turner MS, Trauger JW, Stephens J, LoGrasso P. Characterization and purification of truncated human Rho-kinase II expressed in Sf-21 cells. Arch Biochem Biophys 2002; 405:13-20. [PMID: 12176052 DOI: 10.1016/s0003-9861(02)00249-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Rho-kinase II (ROCK-II) is a serine/threonine kinase that is involved in regulation of smooth muscle contraction and has been shown to contribute to the early stages of axon formation in neurons and the regulation of the neuronal cytoskeleton. Much of what is known about Rho-kinase function comes from cell-biological studies, whereas a paucity of biochemical characterization exists for the enzyme. In an effort to characterize ROCK-II biochemically we have cloned a truncated form of human ROCK-II comprising amino acids 1-543 and overexpressed it in Sf-21 cells. Utilizing the Sf-21/baculovirus expression system we isolated milligram quantities of ROCK-II (1-543) and purified the enzyme to near homogeneity. Optimal expression conditions revealed that infection of Sf-21 cells at a multiplicity of infection of 10 for 72h yielded maximal protein expression. Expression of ROCK-II (1-543) as an N-terminal Flag fusion protein allowed a single-step purification yielding greater than 90% homogeneous protein as assessed by SDS-PAGE. Enzyme activity was linear over a range of enzyme concentrations and times. Capture of phosphorylated, biotinylated peptides on streptavidin membrane allowed assessment of peptide substrate preference and measurement of steady-state rate constants. The data indicated that an 11-mer peptide containing Ser235/Ser236 of the S6 ribosomal protein and a 12-mer peptide containing Thr508 of LIM kinase were preferred substrates for ROCK-II (1-543). Finally, staurosporine had an IC(50) value 215-fold more potent than that of the ROCK inhibitor Y-27632. Collectively these data lay the foundation for the beginning of a biochemical characterization for this enzyme and provide methodology for more detailed biochemical, biophysical, and kinetic analysis.
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Affiliation(s)
- Mary S Turner
- Department of Molecular Neuroscience, Merck Research Laboratories, 3535 General Atomics Court, MRLSDB1, San Diego, CA 92121, USA
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Wisniewski D, LoGrasso P, Calaycay J, Marcy A. Assay for IkappaB kinases using an in vivo biotinylated IkappaB protein substrate. Anal Biochem 1999; 274:220-8. [PMID: 10527519 DOI: 10.1006/abio.1999.4287] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
IkappaB kinases (IKK)-1 and -2 are related kinases that are induced by stimuli such as TNF or IL-1 to phosphorylate serines 32 and 36 of IkappaBalpha, the regulatory subunit of the transcription factor NF-kappaB. A procedure for an IKK protein kinase assay is described that uses an in vivo biotinylated IkappaB protein substrate, [gamma-(33)P]ATP, and capture onto a streptavidin membrane. Residues 1-54 of the IkappaBalpha substrate were expressed as a fusion with glutathione S-transferase (GST) and a short (22 amino acid) biotinylation sequence that allowed modification during bacterial expression. Using the streptavidin capture assay the phosphorylation activities of recombinant IKK-1 and -2 were characterized. The assay provided a convenient way to compare IKK protein and peptide substrate preferences; biotinylated GST-IkappaBalpha(1-54) was more readily phosphorylated by both IKK-1 and IKK-2 compared to biotinylated myelin basic protein or a 20-mer biotinylated peptide containing serines 32 and 36 of IkappaBalpha. IKK-1 had 83-fold less activity than IKK-2, and the IKK-1+2 complex had approximately 2-fold more activity than IKK-2. IKK-1+2 and IKK-2 had similar K(m) values for ATP and GST-biotin-IkappaB(1-54) and were similarly inhibited by staurosporine and two of its analogues K252a and K252b, suggesting that most of the IkappaBalpha kinase activity in the IKK-1+2 complex may be attributed to IKK-2. Several features of the assay including the broad linear binding range of the streptavidin membranes for the protein substrate GST-biotin-IkappaB(1-54) (1-4000 pmol of protein/cm(2)), the low background, and its capacity for both biotinylated peptides and proteins make it a useful tool for quantitating IKK activity. These factors and the ease of expressing in vivo biotinylated GST fusions will make this assay approach suitable for a wide variety of protein kinases.
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Affiliation(s)
- D Wisniewski
- Department of Molecular Design and Diversity, Merck Research Laboratories, Rahway, New Jersey, 07065, USA
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