1
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Chong G, MacKerell AD. Spatial requirements for ITAM signaling in an intracellular natural killer cell model membrane. Biochim Biophys Acta Gen Subj 2022; 1866:130221. [PMID: 35933027 PMCID: PMC9420803 DOI: 10.1016/j.bbagen.2022.130221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/27/2022] [Accepted: 07/31/2022] [Indexed: 11/17/2022]
Abstract
FcγRIIIa-FcεRIγ complexes, upon stimulation by antibodies, cluster to initiate intracellular signaling and activate natural killer (NK) cells. Intracellular signaling involves Lck phosphorylation of ITAMs of each monomer of a FcεRIγ homodimer in a FcγRIIIa-FcεRIγ complex and subsequent binding of two phosphotyrosines (pY) in tandem by a Syk family kinase. However, how FcR clustering triggers ITAM signaling is not resolved. Molecular modeling and dynamics (MD) simulations are applied to generate ensembles of structures of the FcγRIIIa and FcεRIγ homodimeric cytoplasmic tails of FcγRIIIa-FcεRIγ complexes based on the transmembrane helices and cytoplasmic tails spaced 120, 80, and 50 Å apart to model different extents of clustering. Site-identification by ligand competitive saturation method with Monte Carlo sampling (SILCS-MC) is used to model how Lck could phosphorylate a diversity of ITAM conformations. At 80 Å separation between FcγRIIIa-FcεRIγ complexes, Lck can perform multiple phosphorylations on individual and multiple ITAMs across complexes, including potential sequential phosphorylation events. Syk may then potentially bind the two pYs within a single ITAM in tandem in isolated FcγRIIIa-FcεRIγ complexes, as observed in CD3ε and ζ chains of T cell receptors by the Syk family kinase ZAP-70. In addition, at 50 Å separation between complexes, unique to natural killer cells over T cells, Syk could potentially bind in tandem to pYs in different ITAMs across FcγRIIIa-FcεRIγ complexes. Thus, we predict that an ensemble of spatial orientations of the ITAMS of FcγRIIIa-FcεRIγ complexes that occur upon clustering lead to ITAM phosphorylation by Lck and subsequent Syk activity thereby facilitating downstream signaling.
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Affiliation(s)
- Gene Chong
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, United States
| | - Alexander D MacKerell
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, United States.
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2
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Kanagy WK, Cleyrat C, Fazel M, Lucero SR, Bruchez MP, Lidke KA, Wilson BS, Lidke DS. Docking of Syk to FcεRI is enhanced by Lyn but limited in duration by SHIP1. Mol Biol Cell 2022; 33:ar89. [PMID: 35793126 PMCID: PMC9582627 DOI: 10.1091/mbc.e21-12-0603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The high-affinity immunoglobulin E (IgE) receptor, FcεRI, is the primary immune receptor found on mast cells and basophils. Signal initiation is classically attributed to phosphorylation of FcεRI β− and γ-subunits by the Src family kinase (SFK) Lyn, followed by the recruitment and activation of the tyrosine kinase Syk. FcεRI signaling is tuned by the balance between Syk-driven positive signaling and the engagement of inhibitory molecules, including SHIP1. Here, we investigate the mechanistic contributions of Lyn, Syk, and SHIP1 to the formation of the FcεRI signalosome. Using Lyn-deficient RBL-2H3 mast cells, we found that another SFK can weakly monophosphorylate the γ-subunit, yet Syk still binds the incompletely phosphorylated immunoreceptor tyrosine-based activation motifs (ITAMs). Once recruited, Syk further enhances γ-phosphorylation to propagate signaling. In contrast, the loss of SHIP1 recruitment indicates that Lyn is required for phosphorylation of the β-subunit. We demonstrate two noncanonical Syk binding modes, trans γ-bridging and direct β-binding, that can support signaling when SHIP1 is absent. Using single particle tracking, we reveal a novel role of SHIP1 in regulating Syk activity, where the presence of SHIP1 in the signaling complex acts to increase the Syk:receptor off-rate. These data suggest that the composition and dynamics of the signalosome modulate immunoreceptor signaling activities.
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Affiliation(s)
- William K Kanagy
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131
| | - Cédric Cleyrat
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131
| | - Mohamadreza Fazel
- Department of Physics, University of New Mexico, Albuquerque, NM 87131
| | - Shayna R Lucero
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131
| | - Marcel P Bruchez
- Department of Biological Sciences and Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Keith A Lidke
- Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131.,Department of Physics, University of New Mexico, Albuquerque, NM 87131
| | - Bridget S Wilson
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131
| | - Diane S Lidke
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131
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3
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Sevdali E, Block V, Lataretu M, Li H, Smulski CR, Briem JS, Heitz Y, Fischer B, Ramirez NJ, Grimbacher B, Jäck HM, Voll RE, Hölzer M, Schneider P, Eibel H. BAFFR activates PI3K/AKT signaling in human naive but not in switched memory B cells through direct interactions with B cell antigen receptors. Cell Rep 2022; 39:111019. [PMID: 35767961 DOI: 10.1016/j.celrep.2022.111019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 04/27/2022] [Accepted: 06/08/2022] [Indexed: 12/28/2022] Open
Abstract
Binding of BAFF to BAFFR activates in mature B cells PI3K/AKT signaling regulating protein synthesis, metabolic fitness, and survival. In humans, naive and memory B cells express the same levels of BAFFR, but only memory B cells seem to survive without BAFF. Here, we show that BAFF activates PI3K/AKT only in naive B cells and changes the expression of genes regulating migration, proliferation, growth, and survival. BAFF-induced PI3K/AKT activation requires direct interactions between BAFFR and the B cell antigen receptor (BCR) components CD79A and CD79B and is enhanced by the AKT coactivator TCL1A. Compared to memory B cells, naive B cells express more surface BCRs, which interact better with BAFFR than IgG or IgA, thus allowing stronger responses to BAFF. As ablation of BAFFR in naive and memory B cells causes cell death independent of BAFF-induced signaling, BAFFR seems to act also as an intrinsic factor for B cell survival.
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Affiliation(s)
- Eirini Sevdali
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Violeta Block
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Marie Lataretu
- RNA Bioinformatics and High-Throughput Analysis, Faculty of Mathematics and Computer Science, University of Jena, Leutragraben 1, 07743 Jena, Germany
| | - Huiying Li
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Cristian R Smulski
- Medical Physics Department, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida E-Bustillo 9500, R8402AGP Río Negro, San Carlos de Bariloche, Argentina
| | - Jana-Susann Briem
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Yannic Heitz
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Beate Fischer
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Neftali-Jose Ramirez
- Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany; Institute for Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Bodo Grimbacher
- Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany; Institute for Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Hans-Martin Jäck
- Department of Medicine, Division of Immunology, University of Erlangen, Glückstraße 6, 91054 Erlangen, Germany
| | - Reinhard E Voll
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Martin Hölzer
- Methodology and Research Infrastructure, MF1 Bioinformatics, Robert Koch Institute, Nordufer 20, 13353 Berlin, Germany
| | - Pascal Schneider
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges, Switzerland
| | - Hermann Eibel
- Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Breisacherstr. 153, 79110 Freiburg, Germany; Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Breisacherstr. 115, 79106 Freiburg, Germany.
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4
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Prasad AN, Woolsey C, Geisbert JB, Agans KN, Borisevich V, Deer DJ, Mire CE, Cross RW, Fenton KA, Broder CC, Geisbert TW. Resistance of Cynomolgus Monkeys to Nipah and Hendra Virus Disease Is Associated With Cell-Mediated and Humoral Immunity. J Infect Dis 2021; 221:S436-S447. [PMID: 32022850 DOI: 10.1093/infdis/jiz613] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The henipaviruses, Hendra virus (HeV) and Nipah virus (NiV), are capable of causing severe and often lethal respiratory and/or neurologic disease in animals and humans. Given the sporadic nature of henipavirus outbreaks, licensure of vaccines and therapeutics for human use will likely require demonstration of efficacy in animal models that faithfully reproduce the human condition. Currently, the African green monkey (AGM) best mimics human henipavirus-induced disease. METHODS The pathogenic potential of HeV and both strains of NiV (Malaysia, Bangladesh) was assessed in cynomolgus monkeys and compared with henipavirus-infected historical control AGMs. Multiplex gene and protein expression assays were used to compare host responses. RESULTS In contrast to AGMs, in which henipaviruses cause severe and usually lethal disease, HeV and NiVs caused only mild or asymptomatic infections in macaques. All henipaviruses replicated in macaques with similar kinetics as in AGMs. Infection in macaques was associated with activation and predicted recruitment of cytotoxic CD8+ T cells, Th1 cells, IgM+ B cells, and plasma cells. Conversely, fatal outcome in AGMs was associated with aberrant innate immune signaling, complement dysregulation, Th2 skewing, and increased secretion of MCP-1. CONCLUSION The restriction factors identified in macaques can be harnessed for development of effective countermeasures against henipavirus disease.
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Affiliation(s)
- Abhishek N Prasad
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Courtney Woolsey
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Joan B Geisbert
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Krystle N Agans
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Viktoriya Borisevich
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Daniel J Deer
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Chad E Mire
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Robert W Cross
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Karla A Fenton
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
| | - Christopher C Broder
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, Maryland
| | - Thomas W Geisbert
- Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston
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5
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Joshi MK, Burton RA, Wu H, Lipchik AM, Craddock BP, Mo H, Parker LL, Miller WT, Post CB. Substrate binding to Src: A new perspective on tyrosine kinase substrate recognition from NMR and molecular dynamics. Protein Sci 2019; 29:350-359. [PMID: 31697410 DOI: 10.1002/pro.3777] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 11/04/2019] [Accepted: 11/05/2019] [Indexed: 01/01/2023]
Abstract
Most signal transduction pathways in humans are regulated by protein kinases through phosphorylation of their protein substrates. Typical eukaryotic protein kinases are of two major types: those that phosphorylate-specific sequences containing tyrosine (~90 kinases) and those that phosphorylate either serine or threonine (~395 kinases). The highly conserved catalytic domain of protein kinases comprises a smaller N lobe and a larger C lobe separated by a cleft region lined by the activation loop. Prior studies find that protein tyrosine kinases recognize peptide substrates by binding the polypeptide chain along the C-lobe on one side of the activation loop, while serine/threonine kinases bind their substrates in the cleft and on the side of the activation loop opposite to that of the tyrosine kinases. Substrate binding structural studies have been limited to four families of the tyrosine kinase group, and did not include Src tyrosine kinases. We examined peptide-substrate binding to Src using paramagnetic-relaxation-enhancement NMR combined with molecular dynamics simulations. The results suggest Src tyrosine kinase can bind substrate positioning residues C-terminal to the phosphoacceptor residue in an orientation similar to serine/threonine kinases, and unlike other tyrosine kinases. Mutagenesis corroborates this new perspective on tyrosine kinase substrate recognition. Rather than an evolutionary split between tyrosine and serine/threonine kinases, a change in substrate recognition may have occurred within the TK group of the human kinome. Protein tyrosine kinases have long been therapeutic targets, but many marketed drugs have deleterious off-target effects. More accurate knowledge of substrate interactions of tyrosine kinases has the potential for improving drug selectivity.
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Affiliation(s)
- Mehul K Joshi
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Robert A Burton
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana.,Ancestry, Lehi, Utah
| | - Heng Wu
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Andrew M Lipchik
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Barbara P Craddock
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, New York
| | - Huaping Mo
- Purdue Interdepartmental NMR Facility PINMRF, Purdue University, West Lafayette, Indiana
| | - Laurie L Parker
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - W Todd Miller
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, New York.,Department of Veterans Affairs Medical Center, Northport, New York
| | - Carol Beth Post
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
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6
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Dong L, Li Y, Zhang D, Zhang H, Han J, Wang Z, Zhou J, Lu C, Su X. Dietary Apostichopus japonicus Alleviates Diabetes Symptoms and Modulates Genes Expression in Kidney Tissues of db/db Mice. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:154-162. [PMID: 29249162 DOI: 10.1021/acs.jafc.7b04743] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The effects of Apostichopus japonicus enzymatic hydrolysate on the regulation of dyslipidemia, pathoglycemia, and transcription changes in kidney tissues of db/db mice were evaluated. In this study, the symptoms of diabetes in db/db mice were alleviated after 10 weeks of treatments with low (db/db + LD group) and high dose (db/db + HD group) of Apostichopus japonicus enzymatic hydrolysate, and the high dose treatment showed a better antidiabetic effect. Compared with the db/db group, the fasting blood glucose levels (36.84 ± 7.82 vs 25.18 ± 6.84 mmol/L, P < 0.01), the urine glucose levels (45.44 ± 3.93 vs 22.66 ± 5.58 mmol/L, P < 0.01), and the serum insulin sensitivity index (-4.65 ± 0.43 vs -4.74 ± 0.75, P > 0.05) in the db/db + HD group were decreased, whereas the fasting plasma insulin (3.12 ± 1.08 vs 5.54 ± 1.82 μg/L, P < 0.01) and the serum insulin resistance index (5.01 ± 2.02 vs 5.96 ± 2.49, P < 0.05) were increased. Subsequently, the kidney transcription profiles were measured in the db/db group and db/db + HD group via microarray, and the results show that Apostichopus japonicus hydrolysate induced differential expression of 77 genes. Among these genes, the down-regulation of genes ntrK1 and ptpN5 played vital roles, as this effect induced the further down-regulation of neurotrophin tyrosine kinase, protein tyrosine phosphatase, and other transcription factors, which are involved in the classical mitogen-activated protein kinases (MAPK) and p38MAPK signaling pathways. The inhibited MAPK and p38MAPK signaling pathways are involved in glycometabolism and the control of lipid metabolism, and they regulate the occurrence and development of diabetic nephropathy.
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Affiliation(s)
- Lisha Dong
- School of Marine Science, Ningbo University , Ningbo, China 315211
| | - Yanyan Li
- Department of Food Science, Cornell University , Ithaca, New York 14853, United States
| | - Dijun Zhang
- School of Marine Science, Ningbo University , Ningbo, China 315211
| | - Hongyan Zhang
- School of Marine Science, Ningbo University , Ningbo, China 315211
| | - Jiaojiao Han
- School of Marine Science, Ningbo University , Ningbo, China 315211
| | - Zhaoyang Wang
- School of Marine Science, Ningbo University , Ningbo, China 315211
| | - Jun Zhou
- School of Marine Science, Ningbo University , Ningbo, China 315211
| | - Chenyang Lu
- School of Marine Science, Ningbo University , Ningbo, China 315211
| | - Xiurong Su
- School of Marine Science, Ningbo University , Ningbo, China 315211
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7
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de Oliveira PSL, Ferraz FAN, Pena DA, Pramio DT, Morais FA, Schechtman D. Revisiting protein kinase-substrate interactions: Toward therapeutic development. Sci Signal 2016; 9:re3. [PMID: 27016527 DOI: 10.1126/scisignal.aad4016] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Despite the efforts of pharmaceutical companies to develop specific kinase modulators, few drugs targeting kinases have been completely successful in the clinic. This is primarily due to the conserved nature of kinases, especially in the catalytic domains. Consequently, many currently available inhibitors lack sufficient selectivity for effective clinical application. Kinases phosphorylate their substrates to modulate their activity. One of the important steps in the catalytic reaction of protein phosphorylation is the correct positioning of the target residue within the catalytic site. This positioning is mediated by several regions in the substrate binding site, which is typically a shallow crevice that has critical subpockets that anchor and orient the substrate. The structural characterization of this protein-protein interaction can aid in the elucidation of the roles of distinct kinases in different cellular processes, the identification of substrates, and the development of specific inhibitors. Because the region of the substrate that is recognized by the kinase can be part of a linear consensus motif or a nonlinear motif, advances in technology beyond simple linear sequence scanning for consensus motifs were needed. Cost-effective bioinformatics tools are already frequently used to predict kinase-substrate interactions for linear consensus motifs, and new tools based on the structural data of these interactions improve the accuracy of these predictions and enable the identification of phosphorylation sites within nonlinear motifs. In this Review, we revisit kinase-substrate interactions and discuss the various approaches that can be used to identify them and analyze their binding structures for targeted drug development.
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Affiliation(s)
- Paulo Sérgio L de Oliveira
- Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas 13083-970, Brazil
| | - Felipe Augusto N Ferraz
- Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas 13083-970, Brazil
| | - Darlene A Pena
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Dimitrius T Pramio
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Felipe A Morais
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Deborah Schechtman
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil.
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8
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Feng C, Post CB. Insights into the allosteric regulation of Syk association with receptor ITAM, a multi-state equilibrium. Phys Chem Chem Phys 2016; 18:5807-18. [PMID: 26468009 PMCID: PMC4758936 DOI: 10.1039/c5cp05417f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The phosphorylation of interdomain A (IA), a linker region between tandem SH2 domains of Syk tyrosine kinase, regulates the binding affinity for association of Syk with doubly-phosphorylated ITAM regions of the B cell receptor. The mechanism of this allosteric regulation has been suggested to be a switch from the high-affinity bifunctional binding, mediated through both SH2 domains binding two phosphotyrosine residues of ITAM, to a substantially lower-affinity binding of only one SH2 domain. IA phosphorylation triggers the switch by inducing disorder in IA and weakening the SH2-SH2 interaction. The postulated switch to a single-SH2-domain binding mode is examined using NMR to monitor site-specific binding to each SH2 domain of Syk variants engineered to have IA regions that differ in conformational flexibility. The combined analysis of titration curves and NMR line-shapes provides sufficient information to determine the energetics of inter-molecular binding at each SH2 site along with an intra-molecular binding or isomerization step. A less favorable isomerization equilibrium associated with the changes in the SH2-SH2 conformational ensemble and IA flexibility accounts for the inhibition of Syk association with membrane ITAM regions when IA is phosphorylated, and refutes the proposed switch to single-SH2-domain binding. Syk localizes in the cell through its SH2 interactions, and this basis for allosteric regulation of ITAM association proposes for the first time a phosphorylation-dependent model to regulate Syk binding to alternate receptors and other signaling proteins that differ either in the number of residues separating ITAM phosphotyrosines or by having only one phosphotyrosine, a half ITAM.
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Affiliation(s)
- Chao Feng
- Department of Medicinal Chemistry and Molecular Pharmacology, Markey Center for Structural Biology, Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907, USA.
| | - Carol Beth Post
- Department of Medicinal Chemistry and Molecular Pharmacology, Markey Center for Structural Biology, Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907, USA.
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9
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Rosenlöw J, Isaksson L, Mayzel M, Lengqvist J, Orekhov VY. Tyrosine phosphorylation within the intrinsically disordered cytosolic domains of the B-cell receptor: an NMR-based structural analysis. PLoS One 2014; 9:e96199. [PMID: 24769851 PMCID: PMC4000212 DOI: 10.1371/journal.pone.0096199] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 04/04/2014] [Indexed: 11/19/2022] Open
Abstract
Intrinsically disordered proteins are found extensively in cell signaling pathways where they often are targets of posttranslational modifications e.g. phosphorylation. Such modifications can sometimes induce or disrupt secondary structure elements present in the modified protein. CD79a and CD79b are membrane-spanning, signal-transducing components of the B-cell receptor. The cytosolic domains of these proteins are intrinsically disordered and each has an immunoreceptor tyrosine-based activation motif (ITAM). When an antigen binds to the receptor, conserved tyrosines located in the ITAMs are phosphorylated which initiate further downstream signaling. Here we use NMR spectroscopy to examine the secondary structure propensity of the cytosolic domains of CD79a and CD79b in vitro before and after phosphorylation. The phosphorylation patterns are identified through analysis of changes of backbone chemical shifts found for the affected tyrosines and neighboring residues. The number of the phosphorylated sites is confirmed by mass spectrometry. The secondary structure propensities are calculated using the method of intrinsic referencing, where the reference random coil chemical shifts are measured for the same protein under denaturing conditions. Our analysis revealed that CD79a and CD79b both have an overall propensity for α-helical structure that is greatest in the C-terminal region of the ITAM. Phosphorylation of CD79a caused a decrease in helical propensity in the C-terminal ITAM region. For CD79b, the opposite was observed and phosphorylation resulted in an increase of helical propensity in the C-terminal part.
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Affiliation(s)
- Joakim Rosenlöw
- The Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Linnéa Isaksson
- The Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Maxim Mayzel
- The Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Johan Lengqvist
- Proteomics Core Facility at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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10
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Isaksson L, Mayzel M, Saline M, Pedersen A, Rosenlöw J, Brutscher B, Karlsson BG, Orekhov VY. Highly efficient NMR assignment of intrinsically disordered proteins: application to B- and T cell receptor domains. PLoS One 2013; 8:e62947. [PMID: 23667548 PMCID: PMC3647075 DOI: 10.1371/journal.pone.0062947] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/26/2013] [Indexed: 01/27/2023] Open
Abstract
We present an integrated approach for efficient characterization of intrinsically disordered proteins. Batch cell-free expression, fast data acquisition, automated analysis, and statistical validation with data resampling have been combined for achieving cost-effective protein expression, and rapid automated backbone assignment. The new methodology is applied for characterization of five cytosolic domains from T- and B-cell receptors in solution.
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MESH Headings
- Amino Acid Motifs
- Cytosol/metabolism
- Humans
- Intracellular Space/metabolism
- Intrinsically Disordered Proteins/chemistry
- Intrinsically Disordered Proteins/metabolism
- Ligands
- Nuclear Magnetic Resonance, Biomolecular/methods
- Protein Structure, Tertiary
- Receptors, Antigen, B-Cell/chemistry
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Antigen, T-Cell/chemistry
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
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Affiliation(s)
- Linnéa Isaksson
- Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Maxim Mayzel
- Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Maria Saline
- Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Anders Pedersen
- Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Joakim Rosenlöw
- Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | - Bernhard Brutscher
- Institut de Biologie Structurale, Université Grenoble CEA CNRS, Grenoble, France
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11
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Stepanek O, Draber P, Drobek A, Horejsi V, Brdicka T. Nonredundant roles of Src-family kinases and Syk in the initiation of B-cell antigen receptor signaling. THE JOURNAL OF IMMUNOLOGY 2013; 190:1807-18. [PMID: 23335753 DOI: 10.4049/jimmunol.1202401] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
When a BCR on a mature B cell is engaged by its ligand, the cell becomes activated, and the Ab-mediated immune response can be triggered. The initiation of BCR signaling is orchestrated by kinases of the Src and Syk families. However, the proximal BCR-induced phosphorylation remains incompletely understood. According to a model of sequential activation of kinases, Syk acts downstream of Src family kinases (SFKs). In addition, signaling independent of SFKs and initiated by Syk has been proposed. Both hypotheses lack sufficient evidence from relevant B cell models, mainly because of the redundancy of Src family members and the importance of BCR signaling for B cell development. We addressed this issue by analyzing controlled BCR triggering ex vivo on primary murine B cells and on murine and chicken B cell lines. Chemical and Csk-based genetic inhibitor treatments revealed that SFKs are required for signal initiation and Syk activation. In addition, ligand and anti-BCR Ab-induced signaling differ in their sensitivity to the inhibition of SFKs.
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Affiliation(s)
- Ondrej Stepanek
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic
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12
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Abstract
The B-cell receptor (BCR) complex and its associated protein tyrosine kinases play a critical role in the development, proliferation, and survival of normal or malignant B cells. Regulated activity of the BCR complex promotes the expansion of selected B cells and the deletion of unwanted or self-reactive ones. Compounds that inhibit various components of this pathway, including spleen tyrosine kinase, Bruton's tyrosine kinase, and phosphoinositol-3 kinase, have been developed. We summarize the rationale for use of agents that can inhibit BCR signaling to treat patients with either indolent or aggressive B-cell lymphomas, highlight early clinical results, and speculate on the future application of such agents in the treatment of patients with various B-cell lymphomas.
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MESH Headings
- Adenine/analogs & derivatives
- Aminopyridines
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- Lymphoma, Large B-Cell, Diffuse/drug therapy
- Lymphoma, Large B-Cell, Diffuse/metabolism
- Lymphoma, Large B-Cell, Diffuse/pathology
- Lymphoma, Mantle-Cell/drug therapy
- Lymphoma, Mantle-Cell/metabolism
- Lymphoma, Mantle-Cell/pathology
- Morpholines
- Neoplasm Staging
- Niacinamide/analogs & derivatives
- Niacinamide/therapeutic use
- Oxazines/therapeutic use
- Phenylurea Compounds/therapeutic use
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphoinositide-3 Kinase Inhibitors
- Piperidines
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/metabolism
- Purines/therapeutic use
- Pyrazoles/therapeutic use
- Pyridines/therapeutic use
- Pyrimidines/therapeutic use
- Quinazolinones/therapeutic use
- Receptors, Antigen, B-Cell/antagonists & inhibitors
- Receptors, Antigen, B-Cell/chemistry
- Receptors, Antigen, B-Cell/metabolism
- Signal Transduction
- Sorafenib
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Affiliation(s)
- Michael Y Choi
- UC San Diego Moores Cancer Center, La Jolla, CA 92093, USA
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13
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SH3 domains: modules of protein-protein interactions. Biophys Rev 2012; 5:29-39. [PMID: 28510178 DOI: 10.1007/s12551-012-0081-z] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 05/29/2012] [Indexed: 01/01/2023] Open
Abstract
Src homology 3 (SH3) domains are involved in the regulation of important cellular pathways, such as cell proliferation, migration and cytoskeletal modifications. Recognition of polyproline and a number of noncanonical sequences by SH3 domains has been extensively studied by crystallography, nuclear magnetic resonance and other methods. High-affinity peptides that bind SH3 domains are used in drug development as candidates for anticancer treatment. This review summarizes the latest achievements in deciphering structural determinants of SH3 function.
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14
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Geahlen RL. Syk and pTyr'd: Signaling through the B cell antigen receptor. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1115-27. [PMID: 19306898 DOI: 10.1016/j.bbamcr.2009.03.004] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 03/06/2009] [Indexed: 11/18/2022]
Abstract
The B cell receptor (BCR) transduces antigen binding into alterations in the activity of intracellular signaling pathways through its ability to recruit and activate the cytoplasmic protein-tyrosine kinase Syk. The recruitment of Syk to the receptor, its activation and its subsequent interactions with downstream effectors are all regulated by its phosphorylation on tyrosine. This review discusses our current understanding of how this phosphorylation regulates the activity of Syk and its participation in signaling through the BCR.
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Affiliation(s)
- Robert L Geahlen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
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15
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Grande SM, Bannish G, Fuentes-Panana EM, Katz E, Monroe JG. Tonic B-cell and viral ITAM signaling: context is everything. Immunol Rev 2007; 218:214-34. [PMID: 17624955 DOI: 10.1111/j.1600-065x.2007.00535.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The presence of an immunoreceptor tyrosine-based activation motif (ITAM) makes immunoreceptors different from other signaling receptors, like integrins, G-coupled protein receptors, chemokine receptors, and growth factor receptors. This unique motif has the canonical sequence D/Ex(0-2)YxxL/Ix(6-8)YxxL/I, where x represents any amino acid and is present at least once in all immunoreceptor complexes. Immunoreceptors can promote survival, activation, and differentiation by transducing signals through these highly conserved motifs. Traditionally, ITAM signaling is thought to occur in response to ligand-induced aggregation, although evidence indicates that ligand-independent tonic signaling also provides functionally relevant signals. The majority of proteins containing ITAMs are transmembrane proteins that exist as part of immunoreceptor complexes. However, oncogenic viruses also have ITAM-containing proteins. In this review, we discuss what is known about tonic signaling by both cellular and viral ITAM-containing proteins and speculate what we might learn from each context.
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Affiliation(s)
- Shannon M Grande
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
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16
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Abstract
Src tyrosine kinases are essential in numerous cell signaling pathways, and improper functioning of these enzymes has been implicated in many diseases. The activity of Src kinases is regulated by conformational activation, which involves several structural changes within the catalytic domain (CD): the orientation of two lobes of CD; rearrangement of the activation loop (A-loop); and movement of an alpha-helix (alphaC), which is located at the interface between the two lobes, into or away from the catalytic cleft. Conformational activation was investigated using biased molecular dynamics to explore the transition pathway between the active and the down-regulated conformation of CD for the Src-kinase family member Lyn kinase, and to gain insight into the interdependence of these changes. Lobe opening is observed to be a facile motion, whereas movement of the A-loop motion is more complex requiring secondary structure changes as well as communication with alphaC. A key result is that the conformational transition involves a switch in an electrostatic network of six polar residues between the active and the down-regulated conformations. The exchange between interactions links the three main motions of the CD. Kinetic experiments that would demonstrate the contribution of the switched electrostatic network to the enzyme mechanism are proposed. Possible implications for regulation conferred by interdomain interactions are also discussed.
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Affiliation(s)
- Elif Ozkirimli
- Medicinal Chemistry and Molecular Pharmacology Department, Markey Center for Structural Biology and Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907-2091, USA
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17
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Grande SM, Ross SR, Monroe JG. Viral immunoreceptor-associated tyrosine-based activation motifs: potential players in oncogenesis. Future Oncol 2006; 2:301-10. [PMID: 16563097 DOI: 10.2217/14796694.2.2.301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cancer is thought to arise as a consequence of multiple insults to a cell. Mutations that lead to increased expression or activity of proto-oncogenes or decreased expression of tumor suppressors are common insults that have been identified to date. However, when considering tumor viruses, viral proteins that modify cellular gene expression, alter host immune surveillance, or affect signaling pathways are also common players. Notably, several of these tumor viruses encode proteins containing an immunoreceptor-associated tyrosine-based activation motif (ITAM), a signaling motif recently implicated in epithelial cell oncogenesis. As expression of proteins bearing this motif is normally restricted to hematopoietic cells, recent work highlighting the consequences of ITAM expression in epithelial cells suggests it may play a role in solid tumor formation.
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Affiliation(s)
- Shannon M Grande
- Department of Pathology and Laboratory Medicine & Abramson Family Cancer Center, University of Pennsylvania, Philadelphia, PA 19104, USA.
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18
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Goldenberg-Furmanov M, Stein I, Pikarsky E, Rubin H, Kasem S, Wygoda M, Weinstein I, Reuveni H, Ben-Sasson SA. LynIs a Target Gene for Prostate Cancer. Cancer Res 2004; 64:1058-66. [PMID: 14871838 DOI: 10.1158/0008-5472.can-03-2420] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Src-related protein kinase Lyn plays an important role in B-cell activation. However, several lines of evidence suggest that it is also involved in the control of cellular proliferation and the inhibition of apoptosis. We have discovered that Lyn is expressed in normal prostate epithelia, in 95% of primary human prostate cancer (PC) specimens examined, and in all of the PC cell lines that we assayed. Moreover, Lyn knockout mice display abnormal prostate gland morphogenesis, which suggests that Lyn plays an important role in prostate epithelium development and implies that Lyn is a candidate target for specific therapy for PC. Using a drug-design strategy to construct sequence-based peptide inhibitors, a Lyn-specific inhibitor, KRX-123, targeting a unique interaction site within Lyn, was synthesized. KRX-123 was found to inhibit cellular proliferation in three hormone-refractory PC cell lines, DU145, PC3, and TSU-Pr1 with IC(50) values of 2-4 micro M. In vivo, tumor volume of DU145 explants in nude mice was significantly reduced after once-a-week injections of KRX-123, at a dose of 10 mg/kg, for a period of 5 weeks. Histological analyses of the treated tumors indicated extensive apoptosis. Thus, we suggest that Lyn inhibition may serve as a prime target for the treatment of hormone-refractory PC.
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Affiliation(s)
- Mirela Goldenberg-Furmanov
- Department of Experimental Medicine and Cancer Research, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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19
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Niv MY, Rubin H, Cohen J, Tsirulnikov L, Licht T, Peretzman-Shemer A, Cna'an E, Tartakovsky A, Stein I, Albeck S, Weinstein I, Goldenberg-Furmanov M, Tobi D, Cohen E, Laster M, Ben-Sasson SA, Reuveni H. Sequence-based Design of Kinase Inhibitors Applicable for Therapeutics and Target Identification. J Biol Chem 2004; 279:1242-55. [PMID: 14570903 DOI: 10.1074/jbc.m306723200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A platform for specifically modulating kinase-dependent signaling using peptides derived from the catalytic domain of the kinase is presented. This technology, termed KinAce, utilizes the canonical structure of protein kinases. The targeted regions (subdomain V and subdomains IX and X) are analyzed and their sequence, three-dimensional structure, and involvement in protein-protein interaction are highlighted. Short myristoylated peptides were derived from the target regions of the tyrosine kinases c-Kit and Lyn and the serine/threonine kinases 3-phosphoinositide-dependent kinase-1 (PDK1) and Akt/protein kinase B (PKB). For each kinase an active designer peptide is shown to selectively inhibit the signaling of the kinase from which it is derived, and to inhibit cancer cell proliferation in the micromolar range. This technology emerges as an applicable tool for deriving sequence-based selective inhibitors for a broad range of protein kinases as hits that may be further developed into drugs. Moreover, it enables identification of novel kinase targets for selected therapeutic indications as demonstrated in the KinScreen application.
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Affiliation(s)
- Masha Y Niv
- Keryx Biopharmaceuticals, 15 Yad-Haruzim St., Jerusalem 93420, Israel
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20
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Ruzza P, Calderan A, Donella-Deana A, Biondi B, Cesaro L, Osler A, Elardo S, Guiotto A, Pinna LA, Borin G. Conformational constraints of tyrosine in protein tyrosine kinase substrates: Information about preferred bioactive side-chain orientation. Biopolymers 2003; 71:478-88. [PMID: 14517899 DOI: 10.1002/bip.10469] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The side-chain orientation of a tyrosine residue located in a peptide, which is an excellent substrate of Syk tyrosine kinase (A. M. Brunati, A. Donella-Deana, M. Ruzzene, O. Marin, L. A. Pinna, FEBS Letters, 1995, Vol. 367, pp. 149-152), was fixed in the gauche (+) or gauche (-) conformation by using the 7-hydroxy-1,2,3,4-tetrahydro isoquinoline-3-carboxylic (Htc) structure. The tyrosine trans conformation was blocked by using an aminobenzazepine-type (Hba) structure. The proposed side-chain orientations were confirmed by the analysis of the (1)H-NMR parameters: chemical shifts, coupling constants, and nuclear Overhauser effects to the tyrosine constraints in the different analogs. This "rotamer scan" of the phosphorylatable residue allowed us to generate optimal substrates in terms of both phosphorylation efficiency and selectivity for Syk tyrosine kinase. In contrast, these conformationally restricted tyrosine analogs were not tolerated by the Src-related tyrosine kinases Lyn and c-Fgr.
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Affiliation(s)
- Paolo Ruzza
- Institute of Biomolecular Chemistry, Padova Unit, CNR, via Marzolo 1, 35131 Padua, Italy.
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21
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Faeder JR, Hlavacek WS, Reischl I, Blinov ML, Metzger H, Redondo A, Wofsy C, Goldstein B. Investigation of early events in Fc epsilon RI-mediated signaling using a detailed mathematical model. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:3769-81. [PMID: 12646643 DOI: 10.4049/jimmunol.170.7.3769] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aggregation of Fc epsilon RI on mast cells and basophils leads to autophosphorylation and increased activity of the cytosolic protein tyrosine kinase Syk. We investigated the roles of the Src kinase Lyn, the immunoreceptor tyrosine-based activation motifs (ITAMs) on the beta and gamma subunits of Fc epsilon RI, and Syk itself in the activation of Syk. Our approach was to build a detailed mathematical model of reactions involving Fc epsilon RI, Lyn, Syk, and a bivalent ligand that aggregates Fc(epsilon)RI. We applied the model to experiments in which covalently cross-linked IgE dimers stimulate rat basophilic leukemia cells. The model makes it possible to test the consistency of mechanistic assumptions with data that alone provide limited mechanistic insight. For example, the model helps sort out mechanisms that jointly control dephosphorylation of receptor subunits. In addition, interpreted in the context of the model, experimentally observed differences between the beta- and gamma-chains with respect to levels of phosphorylation and rates of dephosphorylation indicate that most cellular Syk, but only a small fraction of Lyn, is available to interact with receptors. We also show that although the beta ITAM acts to amplify signaling in experimental systems where its role has been investigated, there are conditions under which the beta ITAM will act as an inhibitor.
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Affiliation(s)
- James R Faeder
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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22
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Geimonen E, LaMonica R, Springer K, Farooqui Y, Gavrilovskaya IN, Mackow ER. Hantavirus pulmonary syndrome-associated hantaviruses contain conserved and functional ITAM signaling elements. J Virol 2003; 77:1638-43. [PMID: 12502882 PMCID: PMC140783 DOI: 10.1128/jvi.77.2.1638-1643.2003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2002] [Accepted: 10/10/2002] [Indexed: 01/16/2023] Open
Abstract
Hantaviruses infect human endothelial and immune cells, causing two human diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). We have identified key signaling elements termed immunoreceptor tyrosine-based activation motifs (ITAMs) within the G1 cytoplasmic tail of all HPS-causing hantaviruses. ITAMs direct receptor signaling within immune and endothelial cells and the presence of ITAMs in all HPS-causing hantaviruses provides a means for altering normal cellular responses which maintain vascular integrity. The NY-1 G1 ITAM was shown to coprecipitate a complex of phosphoproteins from cells, and the G1 ITAM is a substrate for the Src family kinase Fyn. The hantavirus ITAM coprecipitated Lyn, Syk, and ZAP-70 kinases from T or B cells, while mutagenesis of the ITAM abolished these interactions. In addition, G1 ITAM tyrosines directed intracellular interactions with Syk by mammalian two-hybrid analysis. These findings demonstrate that G1 ITAMs bind key cellular kinases that regulate immune and endothelial cell functions. There is currently no means for establishing the role of the G1 ITAM in hantavirus pathogenesis. However, the conservation of G1 ITAMs in all HPS-causing hantaviruses and the role of these signaling elements in immune and endothelial cells suggest that functional G1 ITAMs are likely to dysregulate normal immune and endothelial cell responses and contribute to hantavirus pathogenesis.
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Affiliation(s)
- Erika Geimonen
- Department of Medicine, SUNY at Stony Brook, New York 11794, USA
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