1
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Ladbury JE, Lin CC, Suen KM. Phase separation enhances probability of receptor signalling and drug targeting. Trends Biochem Sci 2023; 48:428-436. [PMID: 36759237 DOI: 10.1016/j.tibs.2023.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/10/2023] [Accepted: 01/17/2023] [Indexed: 02/10/2023]
Abstract
The probability of a given receptor tyrosine kinase (RTK) triggering a defined cellular outcome is low because of the promiscuous nature of signalling, the randomness of molecular diffusion through the cell, and the ongoing nonfunctional submembrane signalling activity or noise. Signal transduction is therefore a 'numbers game', where enough cell surface receptors and effector proteins must initially be engaged to guarantee formation of a functional signalling complex against a background of redundant events. The presence of intracellular liquid-liquid phase separation (LLPS) at the plasma membrane provides a mechanism through which the probabilistic nature of signalling can be weighted in favour of the required, discrete cellular outcome and mutual exclusivity in signal initiation.
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Affiliation(s)
- John E Ladbury
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Chi-Chuan Lin
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Kin Man Suen
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
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2
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Güven E, Wester MJ, Edwards JS, Halász ÁM. Modeling the Cluster Size Distribution of Vascular Endothelial Growth Factor (VEGF) Receptors. Bioinform Biol Insights 2022; 16:11779322221085078. [PMID: 35356495 PMCID: PMC8958695 DOI: 10.1177/11779322221085078] [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] [Received: 12/09/2021] [Accepted: 02/12/2022] [Indexed: 11/15/2022] Open
Abstract
We previously developed a method of defining receptor clusters in the membrane based on mutual distance and applied it to a set of transmission microscopy images of vascular endothelial growth factor receptors. An optimal length parameter was identified, resulting in cluster identification and a procedure that assigned a geometric shape to each cluster. We showed that the observed particle distribution results were consistent with the random placement of receptors within the clusters and, to a lesser extent, the random placement of the clusters on the cell membrane. Here, we develop and validate a stochastic model of clustering, based on a hypothesis of preexisting domains that have a high affinity for receptors. The proximate objective is to clarify the mechanism behind cluster formation and to estimate the effect on signaling. Receptor-enriched domains may significantly impact signaling pathways that rely on ligand-induced dimerization of receptors. We define a simple statistical model, based on the preexisting domain hypothesis, to predict the probability distribution of cluster sizes. The process yielded sets of parameter values that can readily be used in dynamical calculations as the estimates of the quantitative characteristics of the clustering domains.
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Affiliation(s)
- Emine Güven
- Department of Biomedical Engineering, Düzce University, Düzce, Turkey
| | - Michael J Wester
- Department of Mathematics and Statistics, University of New Mexico, Albuquerque, NM, USA
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, USA
| | - Jeremy S Edwards
- Department of Chemistry and Chemical Biology University of New Mexico, Albuquerque, NM, USA
- Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM, USA
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM, USA
- Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Ádám M Halász
- Mathematics, West Virginia University, Morgantown, WV, USA
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3
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Hager R, Müller U, Ollinger N, Weghuber J, Lanzerstorfer P. Subcellular Dynamic Immunopatterning of Cytosolic Protein Complexes on Microstructured Polymer Substrates. ACS Sens 2021; 6:4076-4088. [PMID: 34652152 PMCID: PMC8630788 DOI: 10.1021/acssensors.1c01574] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
Analysis of protein–protein
interactions in living cells
by protein micropatterning is currently limited to the spatial arrangement
of transmembrane proteins and their corresponding downstream molecules.
Here, we present a robust and straightforward method for dynamic immunopatterning
of cytosolic protein complexes by use of an artificial transmembrane
bait construct in combination with microstructured antibody arrays
on cyclic olefin polymer substrates. As a proof, the method was used
to characterize Grb2-mediated signaling pathways downstream of the
epidermal growth factor receptor (EGFR). Ternary protein complexes
(Shc1:Grb2:SOS1 and Grb2:Gab1:PI3K) were identified, and we found
that EGFR downstream signaling is based on constitutively bound (Grb2:SOS1
and Grb2:Gab1) as well as on agonist-dependent protein associations
with transient interaction properties (Grb2:Shc1 and Grb2:PI3K). Spatiotemporal
analysis further revealed significant differences in stability and
exchange kinetics of protein interactions. Furthermore, we could show
that this approach is well suited to study the efficacy and specificity
of SH2 and SH3 protein domain inhibitors in a live cell context. Altogether,
this method represents a significant enhancement of quantitative subcellular
micropatterning approaches as an alternative to standard biochemical
analyses.
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Affiliation(s)
- Roland Hager
- University of Applied Sciences Upper Austria, School of Engineering, 4600 Wels, Austria
| | - Ulrike Müller
- University of Applied Sciences Upper Austria, School of Engineering, 4600 Wels, Austria
| | - Nicole Ollinger
- Austrian Competence Centre for Feed and Food Quality, Safety & Innovation, Head Office: FFoQSI GmbH, Technopark 1C, 3430 Tulln, Austria
| | - Julian Weghuber
- University of Applied Sciences Upper Austria, School of Engineering, 4600 Wels, Austria
- Austrian Competence Centre for Feed and Food Quality, Safety & Innovation, Head Office: FFoQSI GmbH, Technopark 1C, 3430 Tulln, Austria
| | - Peter Lanzerstorfer
- University of Applied Sciences Upper Austria, School of Engineering, 4600 Wels, Austria
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4
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Franco Nitta C, Green EW, Jhamba ED, Keth JM, Ortiz-Caraveo I, Grattan RM, Schodt DJ, Gibson AC, Rajput A, Lidke KA, Wilson BS, Steinkamp MP, Lidke DS. EGFR transactivates RON to drive oncogenic crosstalk. eLife 2021; 10:63678. [PMID: 34821550 PMCID: PMC8654365 DOI: 10.7554/elife.63678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 11/24/2021] [Indexed: 12/22/2022] Open
Abstract
Crosstalk between different receptor tyrosine kinases (RTKs) is thought to drive oncogenic signaling and allow therapeutic escape. EGFR and RON are two such RTKs from different subfamilies, which engage in crosstalk through unknown mechanisms. We combined high-resolution imaging with biochemical and mutational studies to ask how EGFR and RON communicate. EGF stimulation promotes EGFR-dependent phosphorylation of RON, but ligand stimulation of RON does not trigger EGFR phosphorylation – arguing that crosstalk is unidirectional. Nanoscale imaging reveals association of EGFR and RON in common plasma membrane microdomains. Two-color single particle tracking captured formation of complexes between RON and EGF-bound EGFR. Our results further show that RON is a substrate for EGFR kinase, and that transactivation of RON requires formation of a signaling competent EGFR dimer. These results support a role for direct EGFR/RON interactions in propagating crosstalk, such that EGF-stimulated EGFR phosphorylates RON to activate RON-directed signaling.
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Affiliation(s)
| | - Ellen W Green
- Department of Pathology, University of New Mexico, Albuquerque, United States
| | - Elton D Jhamba
- Department of Pathology, University of New Mexico, Albuquerque, United States
| | - Justine M Keth
- Department of Pathology, University of New Mexico, Albuquerque, United States
| | - Iraís Ortiz-Caraveo
- Department of Pathology, University of New Mexico, Albuquerque, United States
| | - Rachel M Grattan
- Department of Pathology, University of New Mexico, Albuquerque, United States
| | - David J Schodt
- Department of Physics & Astronomy, University of New Mexico, Albuquerque, United States
| | - Aubrey C Gibson
- Department of Pathology, University of New Mexico, Albuquerque, United States
| | - Ashwani Rajput
- Department of Surgery, University of New Mexico, Albuquerque, United States.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, United States
| | - Keith A Lidke
- Department of Physics & Astronomy, University of New Mexico, Albuquerque, United States.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, United States
| | - Bridget S Wilson
- Department of Pathology, University of New Mexico, Albuquerque, United States.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, United States
| | - Mara P Steinkamp
- Department of Pathology, University of New Mexico, Albuquerque, United States.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, United States
| | - Diane S Lidke
- Department of Pathology, University of New Mexico, Albuquerque, United States.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, United States
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5
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Haack F, Köster T, Uhrmacher AM. Receptor/Raft Ratio Is a Determinant for LRP6 Phosphorylation and WNT/β-Catenin Signaling. Front Cell Dev Biol 2021; 9:706731. [PMID: 34485292 PMCID: PMC8416303 DOI: 10.3389/fcell.2021.706731] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/12/2021] [Indexed: 11/21/2022] Open
Abstract
Microdomains or lipid rafts greatly affect the distribution of proteins and peptides in the membrane and play a vital role in the formation and activation of receptor/protein complexes. A prominent example for the decisive impact of lipid rafts on signaling is LRP6, whose localization to the same lipid rafts domain as the kinase CK1γ is crucial for its successful phosphorylation and the subsequent activation of the signalosome, hence WNT/β-catenin signaling. However, according to various experimental measurements, approximately 25 to 35 % of the cell plasma membrane is covered by nanoscopic raft domains with diameters ranging between 10 to 200 nm. Extrapolating/Translating these values to the membrane of a “normal sized” cell yields a raft abundance, that, by far, outnumbers the membrane-associated pathway components of most individual signaling pathway, such as receptor and kinases. To analyze whether and how the quantitative ratio between receptor and rafts affects LRP6 phosphorylation and WNT/β-catenin pathway activation, we present a computational modeling study, that for the first time employs realistic raft numbers in a compartment-based pathway model. Our simulation experiments indicate, that for receptor/raft ratios smaller than 1, i.e., when the number of raft compartments clearly exceeds the number of pathway specific membrane proteins, we observe significant decrease in LRP6 phosphorylation and downstream pathway activity. Our results suggest that pathway specific targeting and sorting mechanism are required to significantly narrow down the receptor/raft ratio and to enable the formation of the LRP6 signalosome, hence signaling.
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Affiliation(s)
- Fiete Haack
- Modeling and Simulation Group, Institute for Visual and Analytic Computing, Institute of Electric Engineering and Computer Science, University of Rostock, Rostock, Germany
| | - Till Köster
- Modeling and Simulation Group, Institute for Visual and Analytic Computing, Institute of Electric Engineering and Computer Science, University of Rostock, Rostock, Germany
| | - Adelinde M Uhrmacher
- Modeling and Simulation Group, Institute for Visual and Analytic Computing, Institute of Electric Engineering and Computer Science, University of Rostock, Rostock, Germany
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6
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Wolf S. Deviating from the Beaten Track: New Twists in Brassinosteroid Receptor Function. Int J Mol Sci 2020; 21:ijms21051561. [PMID: 32106564 PMCID: PMC7084826 DOI: 10.3390/ijms21051561] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/21/2020] [Accepted: 02/22/2020] [Indexed: 12/15/2022] Open
Abstract
A key feature of plants is their plastic development tailored to the environmental conditions. To integrate environmental signals with genetic growth regulatory programs, plants rely on a number of hormonal pathways, which are intimately connected at multiple levels. Brassinosteroids (BRs), a class of plant sterol hormones, are perceived by cell surface receptors and trigger responses instrumental in tailoring developmental programs to environmental cues. Arguably, BR signalling is one of the best-characterized plant signalling pathways, and the molecular composition of the core signal transduction cascade seems clear. However, BR research continues to reveal new twists to re-shape our view on this key signalling circuit. Here, exciting novel findings pointing to the plasma membrane as a key site for BR signalling modulation and integration with other pathways are reviewed and new inputs into the BR signalling pathway and emerging “non-canonical” functions of the BR receptor complex are highlighted. Together, this new evidence underscores the complexity of plant signalling integration and serves as a reminder that highly-interconnected signalling pathways frequently comprise non-linear aspects which are difficult to convey in classical conceptual models.
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Affiliation(s)
- Sebastian Wolf
- Centre for Organismal Studies (COS) Heidelberg, INF230, 69120 Heidelberg, Germany
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7
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Salazar-Cavazos E, Nitta CF, Mitra ED, Wilson BS, Lidke KA, Hlavacek WS, Lidke DS. Multisite EGFR phosphorylation is regulated by adaptor protein abundances and dimer lifetimes. Mol Biol Cell 2020; 31:695-708. [PMID: 31913761 PMCID: PMC7202077 DOI: 10.1091/mbc.e19-09-0548] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Differential epidermal growth factor receptor (EGFR) phosphorylation is thought to couple receptor activation to distinct signaling pathways. However, the molecular mechanisms responsible for biased signaling are unresolved due to a lack of insight into the phosphorylation patterns of full-length EGFR. We extended a single-molecule pull-down technique previously used to study protein-protein interactions to allow for robust measurement of receptor phosphorylation. We found that EGFR is predominantly phosphorylated at multiple sites, yet phosphorylation at specific tyrosines is variable and only a subset of receptors share phosphorylation at the same site, even with saturating ligand concentrations. We found distinct populations of receptors as soon as 1 min after ligand stimulation, indicating early diversification of function. To understand this heterogeneity, we developed a mathematical model. The model predicted that variations in phosphorylation are dependent on the abundances of signaling partners, while phosphorylation levels are dependent on dimer lifetimes. The predictions were confirmed in studies of cell lines with different expression levels of signaling partners, and in experiments comparing low- and high-affinity ligands and oncogenic EGFR mutants. These results reveal how ligand-regulated receptor dimerization dynamics and adaptor protein concentrations play critical roles in EGFR signaling.
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Affiliation(s)
| | | | - Eshan D Mitra
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545
| | | | - Keith A Lidke
- Comprehensive Cancer Center, and.,Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131
| | - William S Hlavacek
- Comprehensive Cancer Center, and.,Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545
| | - Diane S Lidke
- Department of Pathology.,Comprehensive Cancer Center, and
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8
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Chung HK, Zou X, Bajar BT, Brand VR, Huo Y, Alcudia JF, Ferrell JE, Lin MZ. A compact synthetic pathway rewires cancer signaling to therapeutic effector release. Science 2019; 364:364/6439/eaat6982. [PMID: 31048459 DOI: 10.1126/science.aat6982] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 03/05/2019] [Indexed: 12/13/2022]
Abstract
An important goal in synthetic biology is to engineer biochemical pathways to address unsolved biomedical problems. One long-standing problem in molecular medicine is the specific identification and ablation of cancer cells. Here, we describe a method, named Rewiring of Aberrant Signaling to Effector Release (RASER), in which oncogenic ErbB receptor activity, instead of being targeted for inhibition as in existing treatments, is co-opted to trigger therapeutic programs. RASER integrates ErbB activity to specifically link oncogenic states to the execution of desired outputs. A complete mathematical model of RASER and modularity in design enable rational optimization and output programming. Using RASER, we induced apoptosis and CRISPR-Cas9-mediated transcription of endogenous genes specifically in ErbB-hyperactive cancer cells. Delivery of apoptotic RASER by adeno-associated virus selectively ablated ErbB-hyperactive cancer cells while sparing ErbB-normal cells. RASER thus provides a new strategy for oncogene-specific cancer detection and treatment.
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Affiliation(s)
- Hokyung K Chung
- Department of Biology, Stanford University, Stanford, CA, USA.,Department of Neurobiology, Stanford University, Stanford, CA, USA.,Department of Pediatrics, Stanford University, Stanford, CA, USA
| | - Xinzhi Zou
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Bryce T Bajar
- Department of Pediatrics, Stanford University, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Veronica R Brand
- Department of Pediatrics, Stanford University, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Yunwen Huo
- Department of Neurobiology, Stanford University, Stanford, CA, USA.,Department of Pediatrics, Stanford University, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Javier F Alcudia
- Neuroscience Gene Vector and Virus Core, Stanford University, Stanford, CA, USA
| | - James E Ferrell
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Michael Z Lin
- Department of Neurobiology, Stanford University, Stanford, CA, USA. .,Department of Pediatrics, Stanford University, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA.,Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
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9
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In silico prediction of ErbB signal activation from receptor expression profiles through a data analytics pipeline. J Biosci 2018. [DOI: 10.1007/s12038-018-9747-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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10
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Das AA, Jacob E. In silico prediction of ErbB signal activation from receptor expression profiles through a data analytics pipeline. J Biosci 2018; 43:295-306. [PMID: 29872018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The ErbB signalling pathway has been studied extensively owing to its role in normal physiology and its dysregulation in cancer. Reverse engineering by mathematical models use the reductionist approach to characterize the network components. For an emergent, system-level view of the network, we propose a data analytics pipeline that can learn from the data generated by reverse engineering and use it to re-engineer the system with an agent-based approach. Data from a kinetic model that estimates the parameters by fitting to experiments on cell lines, were encoded into rules, for the interactions of the molecular species (agents) involved in biochemical reactions. The agent model, a digital representation of the cell line system, tracks the activation of ErbB1-3 receptors on binding with ligands, resulting in their dimerization, phosphorylation, trafficking and stimulation of downstream signalling through P13-Akt and Erk pathways. The analytics pipeline has been used to mechanistically link HER expression profile to receptor dimerization and activation of downstream signalling pathways. When applied to drug studies, the efficacy of a drug can be investigated in silico. The anti-tumour activity of Pertuzumab, a monoclonal antibody that inhibits HER2 dimerization, was simulated by blocking 80% of the cellular HER2 available, to observe the effect on signal activation.
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Affiliation(s)
- Arya A Das
- Computational Modelling and Simulation Unit, Council of Scientific and Industrial Research, National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Thiruvananthapuram 695 019, India
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11
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Critchley WR, Pellet-Many C, Ringham-Terry B, Harrison MA, Zachary IC, Ponnambalam S. Receptor Tyrosine Kinase Ubiquitination and De-Ubiquitination in Signal Transduction and Receptor Trafficking. Cells 2018; 7:E22. [PMID: 29543760 PMCID: PMC5870354 DOI: 10.3390/cells7030022] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 03/09/2018] [Accepted: 03/13/2018] [Indexed: 12/13/2022] Open
Abstract
Receptor tyrosine kinases (RTKs) are membrane-based sensors that enable rapid communication between cells and their environment. Evidence is now emerging that interdependent regulatory mechanisms, such as membrane trafficking, ubiquitination, proteolysis and gene expression, have substantial effects on RTK signal transduction and cellular responses. Different RTKs exhibit both basal and ligand-stimulated ubiquitination, linked to trafficking through different intracellular compartments including the secretory pathway, plasma membrane, endosomes and lysosomes. The ubiquitin ligase superfamily comprising the E1, E2 and E3 enzymes are increasingly implicated in this post-translational modification by adding mono- and polyubiquitin tags to RTKs. Conversely, removal of these ubiquitin tags by proteases called de-ubiquitinases (DUBs) enables RTK recycling for another round of ligand sensing and signal transduction. The endocytosis of basal and activated RTKs from the plasma membrane is closely linked to controlled proteolysis after trafficking and delivery to late endosomes and lysosomes. Proteolytic RTK fragments can also have the capacity to move to compartments such as the nucleus and regulate gene expression. Such mechanistic diversity now provides new opportunities for modulating RTK-regulated cellular responses in health and disease states.
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Affiliation(s)
- William R Critchley
- Endothelial Cell Biology Unit, School of Molecular & Cellular Biology, University of Leeds, Leeds LS2 9JT, UK.
| | - Caroline Pellet-Many
- Centre for Cardiovascular Biology & Medicine, Rayne Building, University College London, London WC1E 6PT, UK.
| | - Benjamin Ringham-Terry
- Centre for Cardiovascular Biology & Medicine, Rayne Building, University College London, London WC1E 6PT, UK.
| | | | - Ian C Zachary
- Centre for Cardiovascular Biology & Medicine, Rayne Building, University College London, London WC1E 6PT, UK.
| | - Sreenivasan Ponnambalam
- Endothelial Cell Biology Unit, School of Molecular & Cellular Biology, University of Leeds, Leeds LS2 9JT, UK.
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12
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Weddell JC, Chen S, Imoukhuede PI. VEGFR1 promotes cell migration and proliferation through PLCγ and PI3K pathways. NPJ Syst Biol Appl 2017; 4:1. [PMID: 29263797 PMCID: PMC5736688 DOI: 10.1038/s41540-017-0037-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 11/08/2017] [Accepted: 11/21/2017] [Indexed: 12/16/2022] Open
Abstract
The ability to control vascular endothelial growth factor (VEGF) signaling offers promising therapeutic potential for vascular diseases and cancer. Despite this promise, VEGF-targeted therapies are not clinically effective for many pathologies, such as breast cancer. VEGFR1 has recently emerged as a predictive biomarker for anti-VEGF efficacy, implying a functional VEGFR1 role beyond its classically defined decoy receptor status. Here we introduce a computational approach that accurately predicts cellular responses elicited via VEGFR1 signaling. Aligned with our model prediction, we show empirically that VEGFR1 promotes macrophage migration through PLCγ and PI3K pathways and promotes macrophage proliferation through a PLCγ pathway. These results provide new insight into the basic function of VEGFR1 signaling while offering a computational platform to quantify signaling of any receptor.
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Affiliation(s)
- Jared C. Weddell
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
| | - Si Chen
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
| | - P. I. Imoukhuede
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
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13
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Bahrami A, Miraie-Ashtiani SR, Sadeghi M, Najafi A, Ranjbar R. Dynamic modeling of folliculogenesis signaling pathways in the presence of miRNAs expression. J Ovarian Res 2017; 10:76. [PMID: 29258623 PMCID: PMC5735818 DOI: 10.1186/s13048-017-0371-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Accepted: 11/23/2017] [Indexed: 11/10/2022] Open
Abstract
Background TEK signaling plays a very important role in folliculogenesis. It activates Ras/ERK/MYC, PI3K/AKT/mTORC1 and ovarian steroidogenesis activation pathways. These are the main pathways for cell growth, differentiation, migration, adhesion, proliferation, survival and protein synthesis. Results TEK signaling on each of the two important pathways where levels of pERK, pMYC, pAkt, pMCL1 and pEIF4EBP1 are increased in dominant follicles and pMYC is decreased in dominant follicles. Over activation of ERK and MYC which are the main cell growth and proliferation and over activation of Akt, MCl1, mTORC1 and EIF4EBP1 which are the main cell survival and protein synthesis factors act as promoting factors for folliculogenesis. In case of over expression of hsa-miR-30d-3p and hsa-miR-451a, MYC activity level is considerably increased in subordinate follicles. Our simulation results show that in the presence of has-miR-548v and bta-miR-22-3p, downstream factors of pathways are inhibited. Conclusions Our work offers insight into the design of natural biological procedures and makes predictions that can guide further experimental studies on folliculogenesis pathways. Moreover, it defines a simple signal processing unit that may be useful for engineering synthetic biology and genes circuits to carry out cell-based computation. Electronic supplementary material The online version of this article (doi:10.1186/s13048-017-0371-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Abolfazl Bahrami
- Department of Animal Science, University college of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
| | - Seyed Reza Miraie-Ashtiani
- Department of Animal Science, University college of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
| | - Mostafa Sadeghi
- Department of Animal Science, University college of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
| | - Ali Najafi
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Reza Ranjbar
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
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14
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Jadwin JA, Curran TG, Lafontaine AT, White FM, Mayer BJ. Src homology 2 domains enhance tyrosine phosphorylation in vivo by protecting binding sites in their target proteins from dephosphorylation. J Biol Chem 2017; 293:623-637. [PMID: 29162725 DOI: 10.1074/jbc.m117.794412] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 11/17/2017] [Indexed: 02/03/2023] Open
Abstract
Phosphotyrosine (pTyr)-dependent signaling is critical for many cellular processes. It is highly dynamic, as signal output depends not only on phosphorylation and dephosphorylation rates but also on the rates of binding and dissociation of effectors containing phosphotyrosine-dependent binding modules such as Src homology 2 (SH2) and phosphotyrosine-binding (PTB) domains. Previous in vitro studies suggested that binding of SH2 and PTB domains can enhance protein phosphorylation by protecting the sites bound by these domains from phosphatase-mediated dephosphorylation. To test whether this occurs in vivo, we used the binding of growth factor receptor bound 2 (GRB2) to phosphorylated epidermal growth factor receptor (EGFR) as a model system. We analyzed the effects of SH2 domain overexpression on protein tyrosine phosphorylation by quantitative Western and far-Western blotting, mass spectrometry, and computational modeling. We found that SH2 overexpression results in a significant, dose-dependent increase in EGFR tyrosine phosphorylation, particularly of sites corresponding to the binding specificity of the overexpressed SH2 domain. Computational models using experimentally determined EGFR phosphorylation and dephosphorylation rates, and pTyr-EGFR and GRB2 concentrations, recapitulated the experimental findings. Surprisingly, both modeling and biochemical analyses suggested that SH2 domain overexpression does not result in a major decrease in the number of unbound phosphorylated SH2 domain-binding sites. Our results suggest that signaling via SH2 domain binding is buffered over a relatively wide range of effector concentrations and that SH2 domain proteins with overlapping binding specificities are unlikely to compete with one another for phosphosites in vivo.
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Affiliation(s)
- Joshua A Jadwin
- From the Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, and the Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut 06030 and
| | - Timothy G Curran
- the Department of Biological Engineering and Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Adam T Lafontaine
- From the Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, and the Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut 06030 and
| | - Forest M White
- the Department of Biological Engineering and Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Bruce J Mayer
- From the Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, and the Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut 06030 and
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15
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Del Piccolo N, Hristova K. Quantifying the Interaction between EGFR Dimers and Grb2 in Live Cells. Biophys J 2017; 113:1353-1364. [PMID: 28734476 DOI: 10.1016/j.bpj.2017.06.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 05/19/2017] [Accepted: 06/12/2017] [Indexed: 12/21/2022] Open
Abstract
Adaptor proteins are a class of cytoplasmic proteins that bind to phosphorylated residues in receptor tyrosine kinases and trigger signaling cascades that control critically important cellular processes, such as cell survival, growth, differentiation, and motility. Here, we seek to characterize the interaction between epidermal growth factor receptor (EGFR) and the cytoplasmic adaptor protein growth factor receptor-bound protein 2 (Grb2) in a cellular context. To do so, we explore the utility of a highly biologically relevant model system, mammalian cells under reversible osmotic stress, and a recently introduced Förster resonance energy transfer microscopy method, fully quantified spectral imaging. We present a method that allows us to quantify the stoichiometry and the association constant of the EGFR-Grb2 binding interaction in the plasma membrane, in the presence and absence of activating ligand. The method that we introduce can have broad utility in membrane protein research, as it can be applied to different membrane protein-cytoplasmic protein pairs.
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Affiliation(s)
- Nuala Del Piccolo
- Department of Materials Science and Engineering and Institute for NanoBio Technology, Johns Hopkins University, Baltimore, Maryland
| | - Kalina Hristova
- Department of Materials Science and Engineering and Institute for NanoBio Technology, Johns Hopkins University, Baltimore, Maryland.
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16
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Bücherl CA, Jarsch IK, Schudoma C, Segonzac C, Mbengue M, Robatzek S, MacLean D, Ott T, Zipfel C. Plant immune and growth receptors share common signalling components but localise to distinct plasma membrane nanodomains. eLife 2017. [PMID: 28262094 DOI: 10.7554/elife.25114.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023] Open
Abstract
Cell surface receptors govern a multitude of signalling pathways in multicellular organisms. In plants, prominent examples are the receptor kinases FLS2 and BRI1, which activate immunity and steroid-mediated growth, respectively. Intriguingly, despite inducing distinct signalling outputs, both receptors employ common downstream signalling components, which exist in plasma membrane (PM)-localised protein complexes. An important question is thus how these receptor complexes maintain signalling specificity. Live-cell imaging revealed that FLS2 and BRI1 form PM nanoclusters. Using single-particle tracking we could discriminate both cluster populations and we observed spatiotemporal separation between immune and growth signalling platforms. This finding was confirmed by visualising FLS2 and BRI1 within distinct PM nanodomains marked by specific remorin proteins and differential co-localisation with the cytoskeleton. Our results thus suggest that signalling specificity between these pathways may be explained by the spatial separation of FLS2 and BRI1 with their associated signalling components within dedicated PM nanodomains.
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Affiliation(s)
| | - Iris K Jarsch
- Ludwig-Maximilians-Universität München, Institute of Genetics, Martinsried, Germany
| | - Christian Schudoma
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Cécile Segonzac
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Malick Mbengue
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Silke Robatzek
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Daniel MacLean
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Thomas Ott
- Ludwig-Maximilians-Universität München, Institute of Genetics, Martinsried, Germany
| | - Cyril Zipfel
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
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17
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Bücherl CA, Jarsch IK, Schudoma C, Segonzac C, Mbengue M, Robatzek S, MacLean D, Ott T, Zipfel C. Plant immune and growth receptors share common signalling components but localise to distinct plasma membrane nanodomains. eLife 2017; 6. [PMID: 28262094 PMCID: PMC5383397 DOI: 10.7554/elife.25114] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/04/2017] [Indexed: 12/23/2022] Open
Abstract
Cell surface receptors govern a multitude of signalling pathways in multicellular organisms. In plants, prominent examples are the receptor kinases FLS2 and BRI1, which activate immunity and steroid-mediated growth, respectively. Intriguingly, despite inducing distinct signalling outputs, both receptors employ common downstream signalling components, which exist in plasma membrane (PM)-localised protein complexes. An important question is thus how these receptor complexes maintain signalling specificity. Live-cell imaging revealed that FLS2 and BRI1 form PM nanoclusters. Using single-particle tracking we could discriminate both cluster populations and we observed spatiotemporal separation between immune and growth signalling platforms. This finding was confirmed by visualising FLS2 and BRI1 within distinct PM nanodomains marked by specific remorin proteins and differential co-localisation with the cytoskeleton. Our results thus suggest that signalling specificity between these pathways may be explained by the spatial separation of FLS2 and BRI1 with their associated signalling components within dedicated PM nanodomains. DOI:http://dx.doi.org/10.7554/eLife.25114.001 Unlike most animals, plants cannot move away if their environment changes for the worse. Instead, a plant must sense these changes and respond appropriately, for example by changing how much it grows. Disease-causing microbes in the immediate environment represent another potential threat to plants. To detect these microbes, plant cells have proteins called “pattern recognition receptors” in their surface membranes that sense certain molecules from the microbes (similar receptors are found in animals too). When a receptor protein recognises one such microbial molecule, it becomes activated and forms a complex with other proteins referred to as co-receptors. The protein complex then sends a signal into the cell to trigger an immune response. Plants also use similar receptor proteins to sense their own signalling molecules and regulate their growth and development. These growth-related receptors rely on many of the same co-receptors and signalling components as the immunity-related receptors. This posed the question: how can plant cells use the same proteins to trigger different responses to different signals? Bücherl et al. have now used high-resolution microscopy and the model plant Arabidopsis thaliana to show that the plant’s immune receptors and growth receptors are found in separate clusters at the plant cell’s surface membrane. These clusters are only a few hundred nanometres wide, and they also contained other signalling components that are needed to quickly relay the signals into the plant cell. Bücherl et al. suggest that, by organizing their receptors into these physically distinct clusters, plant cells can use similar proteins to sense different signals and respond in then different ways. This idea will need to be tested in future studies. Further work is also needed to understand how these clusters of signalling proteins are assembled and inserted at specific locations within the surface membrane of a plant cell. DOI:http://dx.doi.org/10.7554/eLife.25114.002
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Affiliation(s)
| | - Iris K Jarsch
- Ludwig-Maximilians-Universität München, Institute of Genetics, Martinsried, Germany
| | - Christian Schudoma
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Cécile Segonzac
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Malick Mbengue
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Silke Robatzek
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Daniel MacLean
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Thomas Ott
- Ludwig-Maximilians-Universität München, Institute of Genetics, Martinsried, Germany
| | - Cyril Zipfel
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
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18
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Das AA, Ajayakumar Darsana T, Jacob E. Agent-based re-engineering of ErbB signaling: a modeling pipeline for integrative systems biology. Bioinformatics 2017; 33:726-732. [PMID: 27998938 DOI: 10.1093/bioinformatics/btw709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/08/2016] [Indexed: 11/14/2022] Open
Abstract
Motivation Experiments in systems biology are generally supported by a computational model which quantitatively estimates the parameters of the system by finding the best fit to the experiment. Mathematical models have proved to be successful in reverse engineering the system. The data generated is interpreted to understand the dynamics of the underlying phenomena. The question we have sought to answer is that - is it possible to use an agent-based approach to re-engineer a biological process, making use of the available knowledge from experimental and modelling efforts? Can the bottom-up approach benefit from the top-down exercise so as to create an integrated modelling formalism for systems biology? We propose a modelling pipeline that learns from the data given by reverse engineering, and uses it for re-engineering the system, to carry out in-silico experiments. Results A mathematical model that quantitatively predicts co-expression of EGFR-HER2 receptors in activation and trafficking has been taken for this study. The pipeline architecture takes cues from the population model that gives the rates of biochemical reactions, to formulate knowledge-based rules for the particle model. Agent-based simulations using these rules, support the existing facts on EGFR-HER2 dynamics. We conclude that, re-engineering models, built using the results of reverse engineering, opens up the possibility of harnessing the power pack of data which now lies scattered in literature. Virtual experiments could then become more realistic when empowered with the findings of empirical cell biology and modelling studies. Availability and Implementation Implemented on the Agent Modelling Framework developed in-house. C ++ code templates available in Supplementary material . Contact liz.csir@gmail.com. Supplementary information Supplementary data are available at Bioinformatics online.
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19
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Githaka JM, Vega AR, Baird MA, Davidson MW, Jaqaman K, Touret N. Ligand-induced growth and compaction of CD36 nanoclusters enriched in Fyn induces Fyn signaling. J Cell Sci 2016; 129:4175-4189. [PMID: 27694211 DOI: 10.1242/jcs.188946] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 09/20/2016] [Indexed: 12/30/2022] Open
Abstract
Nanoclustering is an emerging organizational principle for membrane-associated proteins. The functional consequences of nanoclustering for receptor signaling remain largely unknown. Here, we applied quantitative multi-channel high- and super-resolution imaging to analyze the endothelial cell surface receptor CD36, the clustering of which upon binding to multivalent ligands, such as the anti-angiogenic factor thrombospondin-1 (TSP-1), is thought to be crucial for signaling. We found that a substantial fraction of unligated CD36 exists in nanoclusters, which not only promote TSP-1 binding but are also enriched with the downstream effector Fyn. Exposure to multivalent ligands (TSP-1 or anti-CD36 IgM) that result in larger and denser CD36 clusters activates Fyn. Conversely, pharmacological perturbations that prevent the enhancement of CD36 clustering by TSP-1 abrogate Fyn activation. In both cases, there is no detectable change in Fyn enrichment at CD36 nanoclusters. These observations reveal a crucial role for the basal organization of a receptor into nanoclusters that are enriched with the signal-transducing downstream effectors of that receptor, such that enhancement of clustering by multivalent ligands is necessary and sufficient to activate the downstream effector without the need for its de novo recruitment.
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Affiliation(s)
- John Maringa Githaka
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Anthony R Vega
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Michelle A Baird
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Khuloud Jaqaman
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Nicolas Touret
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
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20
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Jadwin JA, Oh D, Curran TG, Ogiue-Ikeda M, Jia L, White FM, Machida K, Yu J, Mayer BJ. Time-resolved multimodal analysis of Src Homology 2 (SH2) domain binding in signaling by receptor tyrosine kinases. eLife 2016; 5:e11835. [PMID: 27071344 PMCID: PMC4841779 DOI: 10.7554/elife.11835] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 03/14/2016] [Indexed: 12/20/2022] Open
Abstract
While the affinities and specificities of SH2 domain-phosphotyrosine interactions have been well characterized, spatio-temporal changes in phosphosite availability in response to signals, and their impact on recruitment of SH2-containing proteins in vivo, are not well understood. To address this issue, we used three complementary experimental approaches to monitor phosphorylation and SH2 binding in human A431 cells stimulated with epidermal growth factor (EGF): 1) phospho-specific mass spectrometry; 2) far-Western blotting; and 3) live cell single-molecule imaging of SH2 membrane recruitment. Far-Western and MS analyses identified both well-established and previously undocumented EGF-dependent tyrosine phosphorylation and binding events, as well as dynamic changes in binding patterns over time. In comparing SH2 binding site phosphorylation with SH2 domain membrane recruitment in living cells, we found in vivo binding to be much slower. Delayed SH2 domain recruitment correlated with clustering of SH2 domain binding sites on the membrane, consistent with membrane retention via SH2 rebinding. DOI:http://dx.doi.org/10.7554/eLife.11835.001 Individual cells in a multicellular organism must receive signals from the environment and from other cells, and adjust their behavior accordingly. Such signals may cause a cell to grow and multiply, move, or even die. Often these signals are received by receptor proteins, which span the cell membrane and thus provide a way for signals from outside the cell to cause changes inside the cell. The tyrosine kinases are one such group of membrane receptors. When a signal binds to a tyrosine kinase, the receptor is activated and it can add chemical tags called phosphates to the part of itself, or a neighboring protein, that is inside the cell. These phosphates provide binding sites for other types of proteins, many of which contain a section called a SH2 domain. This transmits the signal and leads to further changes in the cell. However, there are over a hundred different SH2 domain-containing proteins in human cells and we do not have a clear picture of what exactly happens when receptor tyrosine kinases are activated. Jadwin, Oh et al. have now looked at how the number of SH2 domain binding sites changes over time after a signal is received. The experiments used three different experimental approaches to study a tyrosine kinase called the Epidermal Growth Factor (EGF) receptor, which is often over-active in human cancers. Jadwin, Oh et al. found that the timing of the changes in the number of SH2 domain binding sites on EGF varied widely. The different methods provided different perspectives on exactly when the changes happen, for example, directly observing the binding of SH2 domains to the membrane of living cells under the microscope showed that binding was much slower than expected from other methods that used purified proteins in solutions. This might be due to the receptors taking a relatively long time to form clusters at the membrane after they receive a signal. Further experiments suggested that what happens when EGF is activated may depend not only on the number of SH2 domain binding sites made, but also the timing and the physical arrangement of those sites. A long-term goal for further studies is to understand how various types of signals can lead to different outcomes in the cell. DOI:http://dx.doi.org/10.7554/eLife.11835.002
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Affiliation(s)
- Joshua A Jadwin
- Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, United States
| | - Dongmyung Oh
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, United States
| | - Timothy G Curran
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States.,Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Mari Ogiue-Ikeda
- Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, United States
| | - Lin Jia
- Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, United States
| | - Forest M White
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States.,Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Kazuya Machida
- Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, United States
| | - Ji Yu
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, United States
| | - Bruce J Mayer
- Raymond and Beverly Sackler Laboratory of Molecular Medicine, Department of Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, United States.,Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, United States
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21
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Stites EC, Aziz M, Creamer MS, Von Hoff DD, Posner RG, Hlavacek WS. Use of mechanistic models to integrate and analyze multiple proteomic datasets. Biophys J 2016; 108:1819-1829. [PMID: 25863072 DOI: 10.1016/j.bpj.2015.02.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 02/18/2015] [Accepted: 02/24/2015] [Indexed: 11/30/2022] Open
Abstract
Proteins in cell signaling networks tend to interact promiscuously through low-affinity interactions. Consequently, evaluating the physiological importance of mapped interactions can be difficult. Attempts to do so have tended to focus on single, measurable physicochemical factors, such as affinity or abundance. For example, interaction importance has been assessed on the basis of the relative affinities of binding partners for a protein of interest, such as a receptor. However, multiple factors can be expected to simultaneously influence the recruitment of proteins to a receptor (and the potential of these proteins to contribute to receptor signaling), including affinity, abundance, and competition, which is a network property. Here, we demonstrate that measurements of protein copy numbers and binding affinities can be integrated within the framework of a mechanistic, computational model that accounts for mass action and competition. We use cell line-specific models to rank the relative importance of protein-protein interactions in the epidermal growth factor receptor (EGFR) signaling network for 11 different cell lines. Each model accounts for experimentally characterized interactions of six autophosphorylation sites in EGFR with proteins containing a Src homology 2 and/or phosphotyrosine-binding domain. We measure importance as the predicted maximal extent of recruitment of a protein to EGFR following ligand-stimulated activation of EGFR signaling. We find that interactions ranked highly by this metric include experimentally detected interactions. Proteins with high importance rank in multiple cell lines include proteins with recognized, well-characterized roles in EGFR signaling, such as GRB2 and SHC1, as well as a protein with a less well-defined role, YES1. Our results reveal potential cell line-specific differences in recruitment.
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Affiliation(s)
- Edward C Stites
- Clinical Translational Research Division, Translational Genomics Research Institute, Phoenix, Arizona; Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri.
| | - Meraj Aziz
- Clinical Translational Research Division, Translational Genomics Research Institute, Phoenix, Arizona
| | - Matthew S Creamer
- Clinical Translational Research Division, Translational Genomics Research Institute, Phoenix, Arizona; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut
| | - Daniel D Von Hoff
- Clinical Translational Research Division, Translational Genomics Research Institute, Phoenix, Arizona
| | - Richard G Posner
- Clinical Translational Research Division, Translational Genomics Research Institute, Phoenix, Arizona; Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona.
| | - William S Hlavacek
- Clinical Translational Research Division, Translational Genomics Research Institute, Phoenix, Arizona; Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico.
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22
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Inhibition of Receptor Dimerization as a Novel Negative Feedback Mechanism of EGFR Signaling. PLoS One 2015; 10:e0139971. [PMID: 26465157 PMCID: PMC4605717 DOI: 10.1371/journal.pone.0139971] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/18/2015] [Indexed: 11/19/2022] Open
Abstract
Dimerization of the epidermal growth factor receptor (EGFR) is crucial for initiating signal transduction. We employed raster image correlation spectroscopy to continuously monitor the EGFR monomer-dimer equilibrium in living cells. EGFR dimer formation upon addition of EGF showed oscillatory behavior with a periodicity of about 2.5 min, suggesting the presence of a negative feedback loop to monomerize the receptor. We demonstrated that monomerization of EGFR relies on phospholipase Cγ, protein kinase C, and protein kinase D (PKD), while being independent of Ca2+ signaling and endocytosis. Phosphorylation of the juxtamembrane threonine residues of EGFR (T654/T669) by PKD was identified as the factor that shifts the monomer-dimer equilibrium of ligand bound EGFR towards the monomeric state. The dimerization state of the receptor correlated with the activity of an extracellular signal-regulated kinase, downstream of the EGFR. Based on these observations, we propose a novel, negative feedback mechanism that regulates EGFR signaling via receptor monomerization.
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23
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Cheng HC, Angermann BR, Zhang F, Meier-Schellersheim M. NetworkViewer: visualizing biochemical reaction networks with embedded rendering of molecular interaction rules. BMC SYSTEMS BIOLOGY 2014; 8:70. [PMID: 24934175 PMCID: PMC4094451 DOI: 10.1186/1752-0509-8-70] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 06/05/2014] [Indexed: 01/01/2023]
Abstract
Background Network representations of cell-biological signaling processes frequently contain large numbers of interacting molecular and multi-molecular components that can exist in, and switch between, multiple biochemical and/or structural states. In addition, the interaction categories (associations, dissociations and transformations) in such networks cannot satisfactorily be mapped onto simple arrows connecting pairs of components since their specifications involve information such as reaction rates and conditions with regard to the states of the interacting components. This leads to the challenge of having to reconcile competing objectives: providing a high-level overview without omitting relevant information, and showing interaction specifics while not overwhelming users with too much detail displayed simultaneously. This problem is typically addressed by splitting the information required to understand a reaction network model into several categories that are rendered separately through combinations of visualizations and/or textual and tabular elements, requiring modelers to consult several sources to obtain comprehensive insights into the underlying assumptions of the model. Results We report the development of an application, the Simmune NetworkViewer, that visualizes biochemical reaction networks using iconographic representations of protein interactions and the conditions under which the interactions take place using the same symbols that were used to specify the underlying model with the Simmune Modeler. This approach not only provides a coherent model representation but, moreover, following the principle of “overview first, zoom and filter, then details-on-demand,” can generate an overview visualization of the global network and, upon user request, presents more detailed views of local sub-networks and the underlying reaction rules for selected interactions. This visual integration of information would be difficult to achieve with static network representations or approaches that use scripted model specifications without offering simple but detailed symbolic representations of molecular interactions, their conditions and consequences in terms of biochemical modifications. Conclusions The Simmune NetworkViewer provides concise, yet comprehensive visualizations of reaction networks created in the Simmune framework. In the near future, by adopting the upcoming SBML standard for encoding multi-component, multi-state molecular complexes and their interactions as input, the NetworkViewer will, moreover, be able to offer such visualization for any rule-based model that can be exported to that standard.
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Affiliation(s)
- Hsueh-Chien Cheng
- Laboratory of Systems Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 4, 4 Memorial Drive, 20892 Bethesda, USA.
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24
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Kozer N, Barua D, Henderson C, Nice EC, Burgess AW, Hlavacek WS, Clayton AHA. Recruitment of the adaptor protein Grb2 to EGFR tetramers. Biochemistry 2014; 53:2594-604. [PMID: 24697349 PMCID: PMC4010257 DOI: 10.1021/bi500182x] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Adaptor
protein Grb2 binds phosphotyrosines in the epidermal growth
factor (EGF) receptor (EGFR) and thereby links receptor activation
to intracellular signaling cascades. Here, we investigated how recruitment
of Grb2 to EGFR is affected by the spatial organization and quaternary
state of activated EGFR. We used the techniques of image correlation
spectroscopy (ICS) and lifetime-detected Förster resonance
energy transfer (also known as FLIM-based FRET or FLIM–FRET)
to measure ligand-induced receptor clustering and Grb2 binding to
activated EGFR in BaF/3 cells. BaF/3 cells were stably transfected
with fluorescently labeled forms of Grb2 (Grb2–mRFP) and EGFR
(EGFR–eGFP). Following stimulation of the cells with EGF, we
detected nanometer-scale association of Grb2–mRFP with EGFR–eGFP
clusters, which contained, on average, 4 ± 1 copies of EGFR–eGFP
per cluster. In contrast, the pool of EGFR–eGFP without Grb2–mRFP
had an average cluster size of 1 ± 0.3 EGFR molecules per punctum.
In the absence of EGF, there was no association between EGFR–eGFP
and Grb2–mRFP. To interpret these data, we extended our recently
developed model for EGFR activation, which considers EGFR oligomerization
up to tetramers, to include recruitment of Grb2 to phosphorylated
EGFR. The extended model, with adjustment of one new parameter (the
ratio of the Grb2 and EGFR copy numbers), is consistent with a cluster
size distribution where 2% of EGFR monomers, 5% of EGFR dimers, <1%
of EGFR trimers, and 94% of EGFR tetramers are associated with Grb2.
Together, our experimental and modeling results further implicate
tetrameric EGFR as the key signaling unit and call into question the
widely held view that dimeric EGFR is the predominant signaling unit.
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Affiliation(s)
- Noga Kozer
- Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology , Hawthorn, Victoria 3122, Australia
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25
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Pryor MM, Low-Nam ST, Halász AM, Lidke DS, Wilson BS, Edwards JS. Dynamic transition states of ErbB1 phosphorylation predicted by spatial stochastic modeling. Biophys J 2014; 105:1533-43. [PMID: 24048005 DOI: 10.1016/j.bpj.2013.07.056] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/08/2013] [Accepted: 07/29/2013] [Indexed: 11/25/2022] Open
Abstract
ErbB1 overexpression is strongly linked to carcinogenesis, motivating better understanding of erbB1 dimerization and activation. Recent single-particle-tracking data have provided improved measures of dimer lifetimes and strong evidence that transient receptor coconfinement promotes repeated interactions between erbB1 monomers. Here, spatial stochastic simulations explore the potential impact of these parameters on erbB1 phosphorylation kinetics. This rule-based mathematical model incorporates structural evidence for conformational flux of the erbB1 extracellular domains, as well as asymmetrical orientation of erbB1 cytoplasmic kinase domains during dimerization. The asymmetric dimer model considers the theoretical consequences of restricted transactivation of erbB1 receptors within a dimer, where the N-lobe of one monomer docks with the C-lobe of the second monomer and triggers its catalytic activity. The dynamic nature of the erbB1 phosphorylation state is shown by monitoring activation states of individual monomers as they diffuse, bind, and rebind after ligand addition. The model reveals the complex interplay between interacting liganded and nonliganded species and the influence of their distribution and abundance within features of the membrane landscape.
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Affiliation(s)
- Meghan McCabe Pryor
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico
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26
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Shankaran H, Zhang Y, Tan Y, Resat H. Model-based analysis of HER activation in cells co-expressing EGFR, HER2 and HER3. PLoS Comput Biol 2013; 9:e1003201. [PMID: 23990774 PMCID: PMC3749947 DOI: 10.1371/journal.pcbi.1003201] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/26/2013] [Indexed: 12/21/2022] Open
Abstract
The HER/ErbB family of receptor tyrosine kinases drives critical responses in normal physiology and cancer, and the expression levels of the various HER receptors are critical determinants of clinical outcomes. HER activation is driven by the formation of various dimer complexes between members of this receptor family. The HER dimer types can have differential effects on downstream signaling and phenotypic outcomes. We constructed an integrated mathematical model of HER activation, and trafficking to quantitatively link receptor expression levels to dimerization and activation. We parameterized the model with a comprehensive set of HER phosphorylation and abundance data collected in a panel of human mammary epithelial cells expressing varying levels of EGFR/HER1, HER2 and HER3. Although parameter estimation yielded multiple solutions, predictions for dimer phosphorylation were in agreement with each other. We validated the model using experiments where pertuzumab was used to block HER2 dimerization. We used the model to predict HER dimerization and activation patterns in a panel of human mammary epithelial cells lines with known HER expression levels in response to stimulations with ligands EGF and HRG. Simulations over the range of expression levels seen in various cell lines indicate that: i) EGFR phosphorylation is driven by HER1-HER1 and HER1-HER2 dimers, and not HER1-HER3 dimers, ii) HER1-HER2 and HER2-HER3 dimers both contribute significantly to HER2 activation with the EGFR expression level determining the relative importance of these species, and iii) the HER2-HER3 dimer is largely responsible for HER3 activation. The model can be used to predict phosphorylated dimer levels for any given HER expression profile. This information in turn can be used to quantify the potencies of the various HER dimers, and can potentially inform personalized therapeutic approaches. A family of cell surface molecules called the HER receptor family plays important roles in normal physiology and cancer. This family has four members, HER1-4. These receptors convert signals received from the extracellular environment into cell decisions such as growth and survival – a process termed signal transduction. In particular, HER2 and HER3 are over-expressed in a number of tumors, and their expression levels are associated with abnormal growth and poor clinical prognosis. A key step in HER-mediated signal transduction is the formation of dimer complexes between members of this family. Different dimer types have different potencies for activating normal and aberrant responses. Prediction of the dimerization pattern for a given HER expression level may pave the way for personalized therapeutic approaches targeting specific dimers. Towards this end, we constructed a mathematical model for HER dimerization and activation. We determined unknown model parameters by analyzing HER activation data collected in a panel of human mammary epithelial cells that express different levels of the HER molecules. The model enables us to quantitatively link HER expression levels to receptor dimerization and activation. Further, the model can be used to support additional quantitative investigations into the basic biology of HER-mediated signal transduction.
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Affiliation(s)
- Harish Shankaran
- Computational Biology and Bioinformatics Group, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Yi Zhang
- Computational Biology and Bioinformatics Group, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Yunbing Tan
- School of Electrical Engineering and Computer Science, Washington State University, Pullman, Washington, United States of America
| | - Haluk Resat
- Computational Biology and Bioinformatics Group, Pacific Northwest National Laboratory, Richland, Washington, United States of America
- * E-mail:
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Bücherl CA, van Esse GW, Kruis A, Luchtenberg J, Westphal AH, Aker J, van Hoek A, Albrecht C, Borst JW, de Vries SC. Visualization of BRI1 and BAK1(SERK3) membrane receptor heterooligomers during brassinosteroid signaling. PLANT PHYSIOLOGY 2013; 162:1911-25. [PMID: 23796795 PMCID: PMC3729770 DOI: 10.1104/pp.113.220152] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 06/21/2013] [Indexed: 05/18/2023]
Abstract
The leucine-rich repeat receptor-like kinase BRASSINOSTEROID-INSENSITIVE1 (BRI1) is the main ligand-perceiving receptor for brassinosteroids (BRs) in Arabidopsis (Arabidopsis thaliana). Binding of BRs to the ectodomain of plasma membrane (PM)-located BRI1 receptors initiates an intracellular signal transduction cascade that influences various aspects of plant growth and development. Even though the major components of BR signaling have been revealed and the PM was identified as the main site of BRI1 signaling activity, the very first steps of signal transmission are still elusive. Recently, it was shown that the initiation of BR signal transduction requires the interaction of BRI1 with its SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) coreceptors. In addition, the resolved structure of the BRI1 ectodomain suggested that BRI1-ASSOCIATED KINASE1 [BAK1](SERK3) may constitute a component of the ligand-perceiving receptor complex. Therefore, we investigated the spatial correlation between BRI1 and BAK1(SERK3) in the natural habitat of both leucine-rich repeat receptor-like kinases using comparative colocalization analysis and fluorescence lifetime imaging microscopy. We show that activation of BR signaling by exogenous ligand application resulted in both elevated colocalization between BRI1 and BAK1(SERK3) and an about 50% increase of receptor heterooligomerization in the PM of live Arabidopsis root epidermal cells. However, large populations of BRI1 and BAK1(SERK3) colocalized independently of BRs. Moreover, we could visualize that approximately 7% of the BRI1 PM pool constitutively heterooligomerizes with BAK1(SERK3) in live root cells. We propose that only small populations of PM-located BRI1 and BAK1(SERK3) receptors participate in active BR signaling and that the initiation of downstream signal transduction involves preassembled BRI1-BAK1(SERK3) heterooligomers.
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Affiliation(s)
- Christoph A. Bücherl
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - G. Wilma van Esse
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - Alex Kruis
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - Jeroen Luchtenberg
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - Adrie H. Westphal
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - José Aker
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - Arie van Hoek
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - Catherine Albrecht
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
| | - Jan Willem Borst
- Laboratory of Biochemistry (C.A.B., G.W.v.E., A.K., J.L., A.H.W., J.A., C.A., J.W.B., S.C.d.V.), Laboratory of Biophysics (A.v.H.), and Microspectroscopy Centre (A.v.H., J.W.B.), Department of Agrotechnology and Food Sciences, 6703 HA Wageningen, The Netherlands; and
- Centre for BioSystems Genomics, 6708 PB Wageningen, The Netherlands (J.W.B.)
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Kozer N, Barua D, Orchard S, Nice EC, Burgess AW, Hlavacek WS, Clayton AH. Exploring higher-order EGFR oligomerisation and phosphorylation--a combined experimental and theoretical approach. MOLECULAR BIOSYSTEMS 2013; 9:1849-63. [PMID: 23629589 PMCID: PMC3698845 DOI: 10.1039/c3mb70073a] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The epidermal growth factor receptor (EGFR) kinase is generally considered to be activated by either ligand-induced dimerisation or a ligand-induced conformational change within pre-formed dimers. Ligand-induced higher-order EGFR oligomerisation or clustering has been reported but it is not clear how EGFR oligomers, as distinct from EGFR dimers, influence signaling outputs. To address this question, we combined measures of receptor clustering (microscopy; image correlation spectroscopy) and phosphorylation (Western blots) with modelling of mass-action chemical kinetics. A stable BaF/3 cell-line that contains a high proportion (>90%) of inactive dimers of EGFR-eGFP but no secreted ligand and no other detectable ErbB receptors was used as the model cell system. EGF at concentrations of greater than 1 nM was found to cluster EGFR-eGFP dimers into higher-order complexes and cause parallel increases in EGFR phosphorylation. The kinetics of EGFR clustering and phosphorylation were both rapid, plateauing within 2 minutes after stimulation with 30 nM EGF. A rule-based model was formulated to interpret the data. This model took into account ligand binding, ligand-induced conformational changes in the cytosolic tail, monomer-dimer-trimer-tetramer transitions via ectodomain- and kinase-mediated interactions, and phosphorylation. The model predicts that cyclic EGFR tetramers are the predominant phosphorylated species, in which activated receptor dimers adopt a cyclic side-by-side orientation, and that receptor kinase activation is stabilised by the intramolecular interactions responsible for cyclic tetramerization.
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Affiliation(s)
- Noga Kozer
- Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Dipak Barua
- Theoretical Biology and Biophysics Group, Theoretical Division & Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Suzanne Orchard
- Ludwig Institute for Cancer Research, Melbourne-Parkville Branch, PO Box 2008, Royal Melbourne Hospital, Victoria 3050, Australia
| | - Eduoard C. Nice
- Ludwig Institute for Cancer Research, Melbourne-Parkville Branch, PO Box 2008, Royal Melbourne Hospital, Victoria 3050, Australia
- Department of Biochemistry, Monash University, Clayton, Victoria 3080, Australia
| | - Antony W. Burgess
- Ludwig Institute for Cancer Research, Melbourne-Parkville Branch, PO Box 2008, Royal Melbourne Hospital, Victoria 3050, Australia
| | - William S. Hlavacek
- Theoretical Biology and Biophysics Group, Theoretical Division & Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Andrew H.A. Clayton
- Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
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Halász ÁM, Lai HJ, McCabe MM, Radhakrishnan K, Edwards JS. Analytical solution of steady-state equations for chemical reaction networks with bilinear rate laws. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2013; 10:957-69. [PMID: 24334389 PMCID: PMC4090023 DOI: 10.1109/tcbb.2013.41] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
True steady states are a rare occurrence in living organisms, yet their knowledge is essential for quasi-steady-state approximations, multistability analysis, and other important tools in the investigation of chemical reaction networks (CRN) used to describe molecular processes on the cellular level. Here, we present an approach that can provide closed form steady-state solutions to complex systems, resulting from CRN with binary reactions and mass-action rate laws. We map the nonlinear algebraic problem of finding steady states onto a linear problem in a higher-dimensional space. We show that the linearized version of the steady-state equations obeys the linear conservation laws of the original CRN. We identify two classes of problems for which complete, minimally parameterized solutions may be obtained using only the machinery of linear systems and a judicious choice of the variables used as free parameters. We exemplify our method, providing explicit formulae, on CRN describing signal initiation of two important types of RTK receptor-ligand systems, VEGF and EGF-ErbB1.
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Affiliation(s)
- Ádám M. Halász
- Department of Mathematics, West Virginia University, Morgantown, WV 26506-6310
- corresponding author (, )
| | - Hong-Jian Lai
- Department of Mathematics, West Virginia University, Morgantown, WV 26506-6310
| | - Meghan M. McCabe
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131 ()
| | - Krishnan Radhakrishnan
- Preventive Medicine and Environmental Health, College of Public Health, University of Kentucky, Lexington, KY 40536 ()
| | - Jeremy S. Edwards
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Science Center, Albuquerque, NM 87131 ()
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Haack F, Burrage K, Redmer R, Uhrmacher AM. Studying the role of lipid rafts on protein receptor bindings with cellular automata. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2013; 10:760-770. [PMID: 24091408 DOI: 10.1109/tcbb.2013.40] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
It is widely accepted that lipid rafts promote receptor clustering and thereby facilitate signaling transduction. The role of lipid rafts in inducing and promoting receptor accumulation within the cell membrane has been explored by several computational and experimental studies. However, it remains unclear whether lipid rafts influence the recruitment and binding of proteins from the cytosol as well. To provide an answer to this question a spatial membrane model has been developed based on cellular automata. Our results indicate that lipid rafts indeed influence protein receptor bindings. In particular processes with slow dissociation and binding kinetics are promoted by lipid rafts, whereas fast binding processes are slightly hampered. However, the impact depends on a variety of parameters, such as the size and mobility of the lipid rafts, the induced slow down of receptors within rafts, and also the dissociation and binding kinetics of the cytosolic proteins. Thus, for any individual signaling pathway the influence of lipid rafts on protein binding might be different. To facilitate analyzing this influence given a specific pathway, our approach has been generalized into LiRaM, a modeling and simulation tool for lipid rafts models.
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31
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Chen Y, Short C, Halász ÁM, Edwards JS. The impact of high density receptor clusters on VEGF signaling. ELECTRONIC PROCEEDINGS IN THEORETICAL COMPUTER SCIENCE 2013; 2013:37-52. [PMID: 25506421 PMCID: PMC4262124 DOI: 10.4204/eptcs.??.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Vascular endothelial growth factor (VEGF) signaling is involved in the process of blood vessel development and maintenance. Signaling is initiated by binding of the bivalent VEGF ligand to the membrane-bound receptors (VEGFR), which in turn stimulates receptor dimerization. Herein, we discuss experimental evidence that VEGF receptors localize in caveloae and other regions of the plasma membrane, and for other receptors, it has been shown that receptor clustering has an impact on dimerization and thus also on signaling. Overall, receptor clustering is part of a complex ecosystem of interactions and how receptor clustering impacts dimerization is not well understood. To address these questions, we have formulated the simplest possible model. We have postulated the existence of a single high affinity region in the cell membrane, which acts as a transient trap for receptors. We have defined an ODE model by introducing high- and low-density receptor variables and introduce the corresponding reactions from a realistic model of VEGF signal initiation. Finally, we use the model to investigate the relation between the degree of VEGFR concentration, ligand availability, and signaling. In conclusion, our simulation results provide a deeper understanding of the role of receptor clustering in cell signaling.
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Affiliation(s)
- Ye Chen
- Department of Mathematics, West Virginia University
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Walker F, Rothacker J, Henderson C, Nice EC, Catimel B, Zhang HH, Scott AM, Bailey MF, Orchard SG, Adams TE, Liu Z, Garrett TPJ, Clayton AHA, Burgess AW. Ligand binding induces a conformational change in epidermal growth factor receptor dimers. Growth Factors 2012; 30:394-409. [PMID: 23163584 DOI: 10.3109/08977194.2012.739619] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The activation of the epidermal growth factor receptor (EGFR) kinase requires ligand binding to the extracellular domain (ECD). Previous reports demonstrate that the EGFR-ECD can be crystallized in two conformations - a tethered monomer or, in the presence of ligand, an untethered back-to-back dimer. We use Biosensor analysis to demonstrate that even in the monomeric state different C-terminal extensions of both truncated (EGFR(1-501))-ECD and full-length EGFR(1-621)-ECD can change the conformation of the ligand-binding site. The binding of a monoclonal antibody mAb806, which recognizes the dimer interface, to the truncated EGFR(1-501)-Fc fusion protein is reduced in the presence of ligand, consistent with a change in conformation. On the cell surface, the presence of erythroblastosis B2 (erbB2) increases the binding of mAb806 to the EGFR. The conformation of the erbB2: EGFR heterodimer interface changes when the cells are treated with epidermal growth factor (EGF). We propose that ligand induces kinase-inactive, pre-formed EGFR dimers and heterodimers to change conformation leading to kinase-active tetramers, where kinase activation occurs via an asymmetric interaction between EGFR dimers.
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Affiliation(s)
- Francesca Walker
- Ludwig Institute for Cancer Research Melbourne - Parkville Branch, Australia
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Kiel C, Serrano L. Structural Data in Synthetic Biology Approaches for Studying General Design Principles of Cellular Signaling Networks. Structure 2012; 20:1806-13. [DOI: 10.1016/j.str.2012.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 10/09/2012] [Accepted: 10/10/2012] [Indexed: 12/13/2022]
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Radhakrishnan K, Halász Á, McCabe MM, Edwards JS, Wilson BS. Mathematical simulation of membrane protein clustering for efficient signal transduction. Ann Biomed Eng 2012; 40:2307-18. [PMID: 22669501 PMCID: PMC3822010 DOI: 10.1007/s10439-012-0599-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 05/17/2012] [Indexed: 12/13/2022]
Abstract
Initiation and propagation of cell signaling depend on productive interactions among signaling proteins at the plasma membrane. These diffusion-limited interactions can be influenced by features of the membrane that introduce barriers, such as cytoskeletal corrals, or microdomains that transiently confine both transmembrane receptors and membrane-tethered peripheral proteins. Membrane topographical features can lead to clustering of receptors and other membrane components, even under very dynamic conditions. This review considers the experimental and mathematical evidence that protein clustering impacts cell signaling in complex ways. Simulation approaches used to consider these stochastic processes are discussed.
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Affiliation(s)
| | - Ádám Halász
- Dept. of Mathematics, West Virginia University, Morgantown, WV
| | - Meghan M. McCabe
- Dept. of Chemical Engineering, University of New Mexico, Albuquerque, N M
| | - Jeremy S. Edwards
- Dept. of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, N M
- Dept. of Chemical Engineering, University of New Mexico, Albuquerque, N M
- Cancer Center, University of New Mexico, Albuquerque, N M
| | - Bridget S. Wilson
- Dept. of Pathology, University of New Mexico, Albuquerque, N M
- Cancer Center, University of New Mexico, Albuquerque, N M
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Bidkhori G, Moeini A, Masoudi-Nejad A. Modeling of tumor progression in NSCLC and intrinsic resistance to TKI in loss of PTEN expression. PLoS One 2012; 7:e48004. [PMID: 23133538 PMCID: PMC3483873 DOI: 10.1371/journal.pone.0048004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 09/19/2012] [Indexed: 11/18/2022] Open
Abstract
EGFR signaling plays a very important role in NSCLC. It activates Ras/ERK, PI3K/Akt and STAT activation pathways. These are the main pathways for cell proliferation and survival. We have developed two mathematical models to relate to the different EGFR signaling in NSCLC and normal cells in the presence or absence of EGFR and PTEN mutations. The dynamics of downstream signaling pathways vary in the disease state and activation of some factors can be indicative of drug resistance. Our simulation denotes the effect of EGFR mutations and increased expression of certain factors in NSCLC EGFR signaling on each of the three pathways where levels of pERK, pSTAT and pAkt are increased. Over activation of ERK, Akt and STAT3 which are the main cell proliferation and survival factors act as promoting factors for tumor progression in NSCLC. In case of loss of PTEN, Akt activity level is considerably increased. Our simulation results show that in the presence of erlotinib, downstream factors i.e. pAkt, pSTAT3 and pERK are inhibited. However, in case of loss of PTEN expression in the presence of erlotinib, pAkt level would not decrease which demonstrates that these cells are resistant to erlotinib.
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Affiliation(s)
- Gholamreza Bidkhori
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Ali Moeini
- Department of Algorithms and Computation, College of Engineering, University of Tehran, Tehran, Iran
| | - Ali Masoudi-Nejad
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
- * E-mail:
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Hause RJ, Leung KK, Barkinge JL, Ciaccio MF, Chuu CP, Jones RB. Comprehensive binary interaction mapping of SH2 domains via fluorescence polarization reveals novel functional diversification of ErbB receptors. PLoS One 2012; 7:e44471. [PMID: 22973453 PMCID: PMC3433420 DOI: 10.1371/journal.pone.0044471] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/08/2012] [Indexed: 11/30/2022] Open
Abstract
First-generation interaction maps of Src homology 2 (SH2) domains with receptor tyrosine kinase (RTK) phosphosites have previously been generated using protein microarray (PM) technologies. Here, we developed a large-scale fluorescence polarization (FP) methodology that was able to characterize interactions between SH2 domains and ErbB receptor phosphosites with higher fidelity and sensitivity than was previously achieved with PMs. We used the FP assay to query the interaction of synthetic phosphopeptides corresponding to 89 ErbB receptor intracellular tyrosine sites against 93 human SH2 domains and 2 phosphotyrosine binding (PTB) domains. From 358,944 polarization measurements, the affinities for 1,405 unique biological interactions were determined, 83% of which are novel. In contrast to data from previous reports, our analyses suggested that ErbB2 was not more promiscuous than the other ErbB receptors. Our results showed that each receptor displays unique preferences in the affinity and location of recruited SH2 domains that may contribute to differences in downstream signaling potential. ErbB1 was enriched versus the other receptors for recruitment of domains from RAS GEFs whereas ErbB2 was enriched for recruitment of domains from tyrosine and phosphatidyl inositol phosphatases. ErbB3, the kinase inactive ErbB receptor family member, was predictably enriched for recruitment of domains from phosphatidyl inositol kinases and surprisingly, was enriched for recruitment of domains from tyrosine kinases, cytoskeletal regulatory proteins, and RHO GEFs but depleted for recruitment of domains from phosphatidyl inositol phosphatases. Many novel interactions were also observed with phosphopeptides corresponding to ErbB receptor tyrosines not previously reported to be phosphorylated by mass spectrometry, suggesting the existence of many biologically relevant RTK sites that may be phosphorylated but below the detection threshold of standard mass spectrometry procedures. This dataset represents a rich source of testable hypotheses regarding the biological mechanisms of ErbB receptors.
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Affiliation(s)
- Ronald J. Hause
- The Committee on Genetics, Genomics, and Systems Biology, The Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology, The Gwen and Jules Knapp Center for Biomedical Discovery, The University of Chicago, Chicago, Illinois, United States of America
| | - Kin K. Leung
- The Committee on Cancer Biology, The Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology, The Gwen and Jules Knapp Center for Biomedical Discovery, The University of Chicago, Chicago, Illinois, United States of America
| | - John L. Barkinge
- The Committee on Genetics, Genomics, and Systems Biology, The Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology, The Gwen and Jules Knapp Center for Biomedical Discovery, The University of Chicago, Chicago, Illinois, United States of America
| | - Mark F. Ciaccio
- The Committee on Cellular and Molecular Physiology, The Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology, The Gwen and Jules Knapp Center for Biomedical Discovery, The University of Chicago, Chicago, Illinois, United States of America
| | - Chih-pin Chuu
- Institute of Cellular and System Medicine, and Translational Center for Glandular Malignancies, National Health Research Institutes, Miaoli, Taiwan
| | - Richard B. Jones
- The Committee on Genetics, Genomics, and Systems Biology, The Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology, The Gwen and Jules Knapp Center for Biomedical Discovery, The University of Chicago, Chicago, Illinois, United States of America
- The Committee on Cancer Biology, The Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology, The Gwen and Jules Knapp Center for Biomedical Discovery, The University of Chicago, Chicago, Illinois, United States of America
- The Committee on Cellular and Molecular Physiology, The Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology, The Gwen and Jules Knapp Center for Biomedical Discovery, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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Jaqaman K, Grinstein S. Regulation from within: the cytoskeleton in transmembrane signaling. Trends Cell Biol 2012; 22:515-26. [PMID: 22917551 DOI: 10.1016/j.tcb.2012.07.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 07/17/2012] [Accepted: 07/17/2012] [Indexed: 12/16/2022]
Abstract
There is mounting evidence that the plasma membrane is highly dynamic and organized in a complex manner. The cortical cytoskeleton is proving to be a particularly important regulator of plasmalemmal organization, modulating the mobility of proteins and lipids in the membrane, facilitating their segregation, and influencing their clustering. This organization plays a critical role in receptor-mediated signaling, especially in the case of immunoreceptors, which require lateral clustering for their activation. Based on recent developments, we discuss the structures and mechanisms whereby the cortical cytoskeleton regulates membrane dynamics and organization, and how the nonuniform distribution of immunoreceptors and their self-association may affect activation and signaling.
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Affiliation(s)
- Khuloud Jaqaman
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
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Fast rebinding increases dwell time of Src homology 2 (SH2)-containing proteins near the plasma membrane. Proc Natl Acad Sci U S A 2012; 109:14024-9. [PMID: 22886086 DOI: 10.1073/pnas.1203397109] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Receptor tyrosine kinases (RTKs) control a host of biological functions by phosphorylating tyrosine residues of intracellular proteins upon extracellular ligand binding. The phosphotyrosines (p-Tyr) then recruit a subset of ∼100 Src homology 2 (SH2) domain-containing proteins to the cell membrane. The in vivo kinetics of this process are not well understood. Here we use total internal reflection (TIR) microscopy and single-molecule imaging to monitor interactions between SH2 modules and p-Tyr sites near the cell membrane. We found that the dwell time of SH2 modules within the TIR illumination field is significantly longer than predictions based on chemical dissociation rate constants, suggesting that SH2 modules quickly rebind to nearby p-Tyr sites after dissociation. We also found that, consistent with the rebinding model, the effective diffusion constant is negatively correlated with the respective dwell time for different SH2 domains and the dwell time is positively correlated with the local density of RTK phosphorylation. These results suggest a mechanism whereby signal output can be regulated through the spatial organization of multiple binding sites, which will prompt reevaluation of many aspects of RTK signaling, such as signaling specificity, mechanisms of spatial control, and noise suppression.
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Oliveras-Ferraros C, Cufí S, Queralt B, Vazquez-Martin A, Martin-Castillo B, de Llorens R, Bosch-Barrera J, Brunet J, Menendez JA. Cross-suppression of EGFR ligands amphiregulin and epiregulin and de-repression of FGFR3 signalling contribute to cetuximab resistance in wild-type KRAS tumour cells. Br J Cancer 2012; 106:1406-14. [PMID: 22491422 PMCID: PMC3326676 DOI: 10.1038/bjc.2012.103] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In addition to the mutational status of KRAS, the epidermal growth factor receptor (EGFR) ligands amphiregulin (AREG) and epiregulin (EREG) might function as bona fide biomarkers of cetuximab (Ctx) sensitivity for most EGFR-driven carcinomas. METHODS Lentivirus-delivered small hairpin RNAs were employed to specifically reduce AREG or EREG gene expression in wild-type KRAS A431 squamous cell carcinoma cells. Colony-forming assays were used to monitor the impact of AREG and EREG knockdown on Ctx efficacy. Amphiregulin and EREG protein expression levels were assessed by quantitative ELISA in parental A431 cells and in pooled populations of A431 cells adapted to grow in the presence of Ctx. A phosphoproteomic platform was used to measure the relative level of phosphorylation of 42 distinct receptor tyrosine kinases before and after the acquisition of resistance to Ctx. RESULTS Stable gene silencing of either ligand was found to notably reduce the expression of the other ligand. Parental A431 cells with normal expression levels of AREG/EREG exhibited significantly increased growth inhibition in response to Ctx, compared with derivatives that are engineered to produce minimal AREG/EREG. The parental A431 cells acutely treated with Ctx exhibited reduced basal expression levels of AREG/EREG. Pooled populations of Ctx-resistant A431 cells expressed significantly lower levels of AREG/EREG and were insensitive to the downregulatory effects of Ctx. Phosphoproteomic screen identified a remarkable hyperactivation of FGFR3 in Ctx-resistant A431 cells, which gained sensitivity to the cytotoxic and apoptotic effects of the FGFR3 TK inhibitor PD173074. The A431 parental cells acutely treated with Ctx rapidly activated FGFR3 and their concomitant exposure to Ctx and PD173074 resulted in synergistic apoptosis. CONCLUSION Cross-suppression of AREG/EREG expression may explain the tight co-expression of AREG and EREG, as well as their tendency to be more highly expressed than other EGFR ligands to determine Ctx efficacy. The positive selection for Ctx-resistant tumour cells exhibiting AREG/EREG cross-suppression may have an important role in the emergence of Ctx resistance. As de-repression of FGFR3 activity rapidly replaces the loss of EGFR-ligand signalling in terms of cell proliferation and survival, combinations of Ctx and FGFR3-targeted drugs may be a valuable strategy to enhance the efficacy of single Ctx while preventing or delaying acquired resistance to Ctx.
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Affiliation(s)
- C Oliveras-Ferraros
- Unit of Translational Research, Catalan Institute of Oncology, Girona, Spain
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Telesco SE, Radhakrishnan R. Structural systems biology and multiscale signaling models. Ann Biomed Eng 2012; 40:2295-306. [PMID: 22539148 DOI: 10.1007/s10439-012-0576-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 04/11/2012] [Indexed: 12/13/2022]
Abstract
We review current advances in experimental as well as computational modeling and simulation approaches to structural systems biology, whose overall aim is to build quantitative models of signaling networks while retaining the crucial elements of molecular specificity. We briefly discuss the current and emerging experimental and computational methods, particularly focusing on hybrid and multiscale methods, and highlight several applications in cell signaling with quantitative and predictive capabilities. The scope of such models range from delineating protein-protein interactions to describing clinical implications.
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Affiliation(s)
- Shannon E Telesco
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
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Archuleta MN, McDermott JE, Edwards JS, Resat H. An adaptive coarse graining method for signal transduction in three dimensions. FUNDAMENTA INFORMATICAE 2012; 118:10.3233/FI-2012-720. [PMID: 24357890 PMCID: PMC3865981 DOI: 10.3233/fi-2012-720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The spatio-temporal landscape of the plasma membrane regulates activation and signal transduction of membrane bound receptors by restricting their two-dimensional mobility and by inducing receptor clustering. This regulation also extends to complex formation between receptors and adaptor proteins, which are the intermediate signaling molecules involved in cellular signaling that relay the received cues from cell surface to cytoplasm and eventually to the nucleus. Although their investigation poses challenging technical difficulties, there is a crucial need to understand the impact of the receptor diffusivity, clustering, and spatial heterogeneity, and of receptor-adaptor protein complex formation on the cellular signal transduction patterns. Building upon our earlier studies, we have developed an adaptive coarse-grained Monte Carlo method that can be used to investigate the role of diffusion, clustering and membrane corralling on receptor association and receptor-adaptor protein complex formation dynamics in three dimensions. The new Monte Carlo lattice based approach allowed us to introduce spatial resolution on the 2-D plasma membrane and to model the cytoplasm in three-dimensions. Being a multi-resolution approach, our new method makes it possible to represent various parts of the cellular system at different levels of detail and enabled us to utilize the locally homogeneous assumption when justified (e.g., cytoplasmic region away from the cell membrane) and avoid its use when high spatial resolution is needed (e.g., cell membrane and cytoplasmic region near the membrane) while keeping the required computational complexity manageable. Our results have shown that diffusion has a significant impact on receptor-receptor dimerization and receptor-adaptor protein complex formation kinetics. We have observed an "adaptor protein hopping" mechanism where the receptor binding proteins may hop between receptors to form short-lived transient complexes. This increased residence time of the adaptor proteins near cell membrane and their ability to frequently change signaling partners may explain the increase in signaling efficiency when receptors are clustered. We also hypothesize that the adaptor protein hopping mechanism can cause concurrent or sequential activation of multiple signaling pathways, thus leading to crosstalk between diverse biological functions.
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Affiliation(s)
- Michelle N Archuleta
- Chemical and Nuclear Engineering Department, University of New Mexico, Albuquerque, NM 87131, USA
| | - Jason E McDermott
- Computational Biology and Bioinformatics Group, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Jeremy S Edwards
- Molecular Genetics and Microbiology Department, UNM Cancer Research and Treatment Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Haluk Resat
- Computational Biology and Bioinformatics Group, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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Wangorsch G, Butt E, Mark R, Hubertus K, Geiger J, Dandekar T, Dittrich M. Time-resolved in silico modeling of fine-tuned cAMP signaling in platelets: feedback loops, titrated phosphorylations and pharmacological modulation. BMC SYSTEMS BIOLOGY 2011; 5:178. [PMID: 22034949 PMCID: PMC3247139 DOI: 10.1186/1752-0509-5-178] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 10/28/2011] [Indexed: 02/13/2023]
Abstract
Background Hemostasis is a critical and active function of the blood mediated by platelets. Therefore, the prevention of pathological platelet aggregation is of great importance as well as of pharmaceutical and medical interest. Endogenous platelet inhibition is predominantly based on cyclic nucleotides (cAMP, cGMP) elevation and subsequent cyclic nucleotide-dependent protein kinase (PKA, PKG) activation. In turn, platelet phosphodiesterases (PDEs) and protein phosphatases counterbalance their activity. This main inhibitory pathway in human platelets is crucial for countervailing unwanted platelet activation. Consequently, the regulators of cyclic nucleotide signaling are of particular interest to pharmacology and therapeutics of atherothrombosis. Modeling of pharmacodynamics allows understanding this intricate signaling and supports the precise description of these pivotal targets for pharmacological modulation. Results We modeled dynamically concentration-dependent responses of pathway effectors (inhibitors, activators, drug combinations) to cyclic nucleotide signaling as well as to downstream signaling events and verified resulting model predictions by experimental data. Experiments with various cAMP affecting compounds including anti-platelet drugs and their combinations revealed a high fidelity, fine-tuned cAMP signaling in platelets without cross-talk to the cGMP pathway. The model and the data provide evidence for two independent feedback loops: PKA, which is activated by elevated cAMP levels in the platelet, subsequently inhibits adenylyl cyclase (AC) but as well activates PDE3. By multi-experiment fitting, we established a comprehensive dynamic model with one predictive, optimized and validated set of parameters. Different pharmacological conditions (inhibition, activation, drug combinations, permanent and transient perturbations) are successfully tested and simulated, including statistical validation and sensitivity analysis. Downstream cyclic nucleotide signaling events target different phosphorylation sites for cAMP- and cGMP-dependent protein kinases (PKA, PKG) in the vasodilator-stimulated phosphoprotein (VASP). VASP phosphorylation as well as cAMP levels resulting from different drug strengths and combined stimulants were quantitatively modeled. These predictions were again experimentally validated. High sensitivity of the signaling pathway at low concentrations is involved in a fine-tuned balance as well as stable activation of this inhibitory cyclic nucleotide pathway. Conclusions On the basis of experimental data, literature mining and database screening we established a dynamic in silico model of cyclic nucleotide signaling and probed its signaling sensitivity. Thoroughly validated, it successfully predicts drug combination effects on platelet function, including synergism, antagonism and regulatory loops.
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Affiliation(s)
- Gaby Wangorsch
- Department of Bioinformatics, Biocenter, University of Würzburg, Germany
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Wilma van Esse G, Westphal AH, Surendran RP, Albrecht C, van Veen B, Borst JW, de Vries SC. Quantification of the brassinosteroid insensitive1 receptor in planta. PLANT PHYSIOLOGY 2011; 156:1691-700. [PMID: 21617031 PMCID: PMC3149942 DOI: 10.1104/pp.111.179309] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 05/25/2011] [Indexed: 05/05/2023]
Abstract
In plants, green fluorescent protein (GFP) is routinely used to determine the subcellular location of fusion proteins. Here, we show that confocal imaging can be employed to approximate the number of GFP-labeled protein molecules present in living Arabidopsis (Arabidopsis thaliana) root cells. The technique involves calibration with soluble GFP to provide a usable protein concentration range within the confocal volume of the microscope. As a proof of principle, we quantified the Brassinosteroid Insensitive1 (BRI1) receptor fused to GFP, under control of its own promoter. The number of BRI1-GFP molecules per root epidermal cell ranges from 22,000 in the meristem and 130,000 in the elongation zone to 80,000 in the maturation zone, indicating that up to 6-fold differences in BRI1 receptor content exist. In contrast, when taking into account differences in cell size, BRI1-GFP receptor density in the plasma membrane is kept constant at 12 receptors μm⁻² in all cells throughout the meristem and elongation zone. Only the quiescent center and columella cells deviate from this pattern and have 5 to 6 receptors μm⁻². Remarkably, root cell sensitivity toward brassinosteroids appears to coincide with uniform meristem receptor density.
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Affiliation(s)
- G Wilma van Esse
- Department of Agrotechnology and Food Sciences, Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands.
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García-Peñarrubia P, Gálvez JJ, Gálvez J. Spatio-temporal dependence of the signaling response in immune-receptor trafficking networks regulated by cell density: a theoretical model. PLoS One 2011; 6:e21786. [PMID: 21789180 PMCID: PMC3136476 DOI: 10.1371/journal.pone.0021786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 06/09/2011] [Indexed: 12/04/2022] Open
Abstract
Cell signaling processes involve receptor trafficking through highly connected networks of interacting components. The binding of surface receptors to their specific ligands is a key factor for the control and triggering of signaling pathways. In most experimental systems, ligand concentration and cell density vary within a wide range of values. Dependence of the signal response on cell density is related with the extracellular volume available per cell. This dependence has previously been studied using non-spatial models which assume that signaling components are well mixed and uniformly distributed in a single compartment. In this paper, a mathematical model that shows the influence exerted by cell density on the spatio-temporal evolution of ligands, cell surface receptors, and intracellular signaling molecules is developed. To this end, partial differential equations were used to model ligand and receptor trafficking dynamics through the different domains of the whole system. This enabled us to analyze several interesting features involved with these systems, namely: a) how the perturbation caused by the signaling response propagates through the system; b) receptor internalization dynamics and how cell density affects the robustness of dose-response curves upon variation of the binding affinity; and c) that enhanced correlations between ligand input and system response are obtained under conditions that result in larger perturbations of the equilibrium . Finally, the results are compared with those obtained by considering that the above components are well mixed in a single compartment.
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Affiliation(s)
- Pilar García-Peñarrubia
- Department of Biochemistry and Molecular Biology and Immunology, School of Medicine, University of Murcia, Murcia, Spain
| | - Juan J. Gálvez
- Department of Information and Communications Engineering, Computer Science Faculty, University of Murcia, Murcia, Spain
| | - Jesús Gálvez
- Department of Physical Chemistry, Faculty of Chemistry, University of Murcia, Murcia, Spain
- * E-mail:
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Selvarajoo K. Macroscopic law of conservation revealed in the population dynamics of Toll-like receptor signaling. Cell Commun Signal 2011; 9:9. [PMID: 21507223 PMCID: PMC3103489 DOI: 10.1186/1478-811x-9-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 04/20/2011] [Indexed: 11/23/2022] Open
Abstract
Stimulating the receptors of a single cell generates stochastic intracellular signaling. The fluctuating response has been attributed to the low abundance of signaling molecules and the spatio-temporal effects of diffusion and crowding. At population level, however, cells are able to execute well-defined deterministic biological processes such as growth, division, differentiation and immune response. These data reflect biology as a system possessing microscopic and macroscopic dynamics. This commentary discusses the average population response of the Toll-like receptor (TLR) 3 and 4 signaling. Without requiring detailed experimental data, linear response equations together with the fundamental law of information conservation have been used to decipher novel network features such as unknown intermediates, processes and cross-talk mechanisms. For single cell response, however, such simplicity seems far from reality. Thus, as observed in any other complex systems, biology can be considered to possess order and disorder, inheriting a mixture of predictable population level and unpredictable single cell outcomes.
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Affiliation(s)
- Kumar Selvarajoo
- Institute for Advanced Biosciences, Keio University, Baba-Cho, 14-1, Tsuruoka, Yamagata, 997-0035 Japan.
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Dishevelled interacts with the DIX domain polymerization interface of Axin to interfere with its function in down-regulating β-catenin. Proc Natl Acad Sci U S A 2011; 108:1937-42. [PMID: 21245303 DOI: 10.1073/pnas.1017063108] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Wnt/β-catenin signaling controls numerous steps in normal animal development and can also cause cancer if inappropriately activated. In the absence of Wnt, β-catenin is targeted continuously for proteasomal degradation by the Axin destruction complex, whose activity is blocked upon Wnt stimulation by Dishevelled, which recruits Axin to the plasma membrane and assembles it into a signalosome. This key event during Wnt signal transduction depends on dynamic head-to-tail polymerization by the DIX domain of Dishevelled. Here, we use rescue assays in Drosophila tissues and functional assays in human cells to show that polymerization-blocking mutations in the DIX domain of Axin disable its effector function in down-regulating Armadillo/β-catenin and its response to Dishevelled during Wnt signaling. Intriguingly, NMR spectroscopy revealed that the purified DIX domains of the two proteins interact with each other directly through their polymerization interfaces, whereby the same residues mediate both homo- and heterotypic interactions. This result implies that Dishevelled has the potential to act as a "natural" dominant-negative, binding to the polymerization interface of Axin's DIX domain to interfere with its self-assembly, thereby blocking its effector function.
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