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Wirth D, Özdemir E, Wimley WC, Pasquale EB, Hristova K. Transmembrane helix interactions regulate oligomerization of the receptor tyrosine kinase EphA2. J Biol Chem 2024; 300:107441. [PMID: 38838777 PMCID: PMC11263659 DOI: 10.1016/j.jbc.2024.107441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/27/2024] [Accepted: 05/28/2024] [Indexed: 06/07/2024] Open
Abstract
The transmembrane helices of receptor tyrosine kinases (RTKs) have been proposed to switch between two different dimeric conformations, one associated with the inactive RTK and the other with the active RTK. Furthermore, recent work has demonstrated that some full-length RTKs are associated into oligomers that are larger than dimers, raising questions about the roles of the TM helices in the assembly and function of these oligomers. Here we probe the roles of the TM helices in the assembly of EphA2 RTK oligomers in the plasma membrane. We employ mutagenesis to evaluate the relevance of a published NMR dimeric structure of the isolated EphA2 TM helix in the context of the full-length EphA2 in the plasma membrane. We use two fluorescence methods, Förster Resonance Energy Transfer and Fluorescence Intensity Fluctuations spectrometry, which yield complementary information about the EphA2 oligomerization process. These studies reveal that the TM helix mutations affect the stability, structure, and size of EphA2 oligomers. However, the effects are multifaceted and point to a more complex role of the TM helix than the one expected from the "TM dimer switch" model.
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Affiliation(s)
- Daniel Wirth
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Ece Özdemir
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - William C Wimley
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, Louisiana, USA
| | - Elena B Pasquale
- Cancer Metabolism and Microenvironment Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
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2
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Singh PK, Rybak JA, Schuck RJ, Barrera FN, Smith AW. Phosphatidylinositol (4,5)-bisphosphate drives the formation of EGFR and EphA2 complexes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.03.592400. [PMID: 38746348 PMCID: PMC11092790 DOI: 10.1101/2024.05.03.592400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Receptor tyrosine kinases (RTKs) regulate many cellular functions and are important targets in pharmaceutical development, particularly in cancer treatment. EGFR and EphA2 are two key RTKs that are associated with oncogenic phenotypes. Several studies have reported functional interplay between these receptors, but the mechanism of interaction is still unresolved. Here we utilize a time-resolved fluorescence spectroscopy called PIE-FCCS to resolve EGFR and EphA2 interactions in live cells. We tested the role of ligands and found that EGF, but not ephrin A1 (EA1), stimulated hetero-multimerization between the receptors. To determine the effect of anionic lipids, we targeted phospholipase C (PLC) activity to alter the abundance of phosphatidylinositol (4,5)-bisphosphate (PIP 2 ). We found that higher PIP 2 levels increased homo-multimerization of both EGFR and EphA2, as well as hetero-multimerization. This study provides a direct characterization of EGFR and EphA2 interactions in live cells and shows that PIP 2 can have a substantial effect on the spatial organization of RTKs.
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3
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Karl K, Del Piccolo N, Light T, Roy T, Dudeja P, Ursachi VC, Fafilek B, Krejci P, Hristova K. Ligand bias underlies differential signaling of multiple FGFs via FGFR1. eLife 2024; 12:RP88144. [PMID: 38568193 PMCID: PMC10990489 DOI: 10.7554/elife.88144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
Abstract
The differential signaling of multiple FGF ligands through a single fibroblast growth factor (FGF) receptor (FGFR) plays an important role in embryonic development. Here, we use quantitative biophysical tools to uncover the mechanism behind differences in FGFR1c signaling in response to FGF4, FGF8, and FGF9, a process which is relevant for limb bud outgrowth. We find that FGF8 preferentially induces FRS2 phosphorylation and extracellular matrix loss, while FGF4 and FGF9 preferentially induce FGFR1c phosphorylation and cell growth arrest. Thus, we demonstrate that FGF8 is a biased FGFR1c ligand, as compared to FGF4 and FGF9. Förster resonance energy transfer experiments reveal a correlation between biased signaling and the conformation of the FGFR1c transmembrane domain dimer. Our findings expand the mechanistic understanding of FGF signaling during development and bring the poorly understood concept of receptor tyrosine kinase ligand bias into the spotlight.
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Affiliation(s)
- Kelly Karl
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Nuala Del Piccolo
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Taylor Light
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Tanaya Roy
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Pooja Dudeja
- Department of Biology, Faculty of Medicine, Masaryk UniversityBrnoCzech Republic
- Institute of Animal Physiology and Genetics of the CASBrnoCzech Republic
| | - Vlad-Constantin Ursachi
- Department of Biology, Faculty of Medicine, Masaryk UniversityBrnoCzech Republic
- International Clinical Research Center, St. Anne's University HospitalBrnoCzech Republic
| | - Bohumil Fafilek
- Department of Biology, Faculty of Medicine, Masaryk UniversityBrnoCzech Republic
- Institute of Animal Physiology and Genetics of the CASBrnoCzech Republic
- International Clinical Research Center, St. Anne's University HospitalBrnoCzech Republic
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk UniversityBrnoCzech Republic
- Institute of Animal Physiology and Genetics of the CASBrnoCzech Republic
- International Clinical Research Center, St. Anne's University HospitalBrnoCzech Republic
| | - Kalina Hristova
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins UniversityBaltimoreUnited States
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4
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Pasquale EB. Eph receptors and ephrins in cancer progression. Nat Rev Cancer 2024; 24:5-27. [PMID: 37996538 PMCID: PMC11015936 DOI: 10.1038/s41568-023-00634-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/03/2023] [Indexed: 11/25/2023]
Abstract
Evidence implicating Eph receptor tyrosine kinases and their ephrin ligands (that together make up the 'Eph system') in cancer development and progression has been accumulating since the discovery of the first Eph receptor approximately 35 years ago. Advances in the past decade and a half have considerably increased the understanding of Eph receptor-ephrin signalling mechanisms in cancer and have uncovered intriguing new roles in cancer progression and drug resistance. This Review focuses mainly on these more recent developments. I provide an update on the different mechanisms of Eph receptor-ephrin-mediated cell-cell communication and cell autonomous signalling, as well as on the interplay of the Eph system with other signalling systems. I further discuss recent advances in elucidating how the Eph system controls tumour expansion, invasiveness and metastasis, supports cancer stem cells, and drives therapy resistance. In addition to functioning within cancer cells, the Eph system also mediates the reciprocal communication between cancer cells and cells of the tumour microenvironment. The involvement of the Eph system in tumour angiogenesis is well established, but recent findings also demonstrate roles in immune cells, cancer-associated fibroblasts and the extracellular matrix. Lastly, I discuss strategies under evaluation for therapeutic targeting of Eph receptors-ephrins in cancer and conclude with an outlook on promising future research directions.
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Affiliation(s)
- Elena B Pasquale
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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5
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Monsen VT, Attramadal H. Structural insights into regulation of CCN protein activities and functions. J Cell Commun Signal 2023:10.1007/s12079-023-00768-5. [PMID: 37245184 DOI: 10.1007/s12079-023-00768-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/07/2023] [Indexed: 05/29/2023] Open
Abstract
CCN proteins play important functions during development, in repair mechanisms following tissue injury, as well as in pathophysiologic mechanisms of metastasis of cancer. CCNs are secreted proteins that have a multimodular structure and are categorized as matricellular proteins. Although the prevailing view is that CCN proteins regulate biologic processes by interacting with a wide array of other proteins in the microenvironment of the extracellular matrix, the molecular mechanisms of action of CCN proteins are still poorly understood. Not dissuading the current view, however, the recent appreciation that these proteins are signaling proteins in their own right and may even be considered preproproteins controlled by endopeptidases to release a C-terminal bioactive peptide has opened new avenues of research. Also, the recent resolution of the crystal structure of two of the domains of CCN3 have provided new knowledge with implications for the entire CCN family. These resolved structures in combination with structural predictions based upon the AlphaFold artificial intelligence tool provide means to shed new light on CCN functions in context of the notable literature in the field. CCN proteins have emerged as important therapeutic targets in several disease conditions, and clinical trials are currently ongoing. Thus, a review that critically discusses structure - function relationship of CCN proteins, in particular as it relates to interactions with other proteins in the extracellular milieu and on the cell surface, as well as to cell signaling activities of these proteins, is very timely. Suggested mechanism for activation and inhibition of signaling by the CCN protein family (graphics generated with BioRender.com ).
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Affiliation(s)
- Vivi Talstad Monsen
- Institute for Surgical Research, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Håvard Attramadal
- Institute for Surgical Research, Oslo University Hospital, Oslo, Norway.
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
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6
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Stoneman MR, Raicu V. Fluorescence-Based Detection of Proteins and Their Interactions in Live Cells. J Phys Chem B 2023. [PMID: 37205844 DOI: 10.1021/acs.jpcb.3c01419] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Recent advances in fluorescence-based microscopy techniques, such as single molecule fluorescence, Förster resonance energy transfer (FRET), fluorescence intensity fluctuations analysis, and super-resolution microscopy have expanded our ability to study proteins in greater detail within their native cellular environment and to investigate the roles that protein interactions play in biological functions, such as inter- and intracellular signaling and cargo transport. In this Perspective, we provide an up-to-date overview of the current state of the art in fluorescence-based detection of proteins and their interactions in living cells with an emphasis on recent developments that have facilitated the characterization of the spatial and temporal organization of proteins into oligomeric complexes in the presence and absence of natural and artificial ligands. Further advancements in this field will only deepen our understanding of the underlying mechanisms of biological processes and help develop new therapeutic targets.
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Affiliation(s)
- Michael R Stoneman
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Valerică Raicu
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
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7
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Precise assembly of inside-out cell membrane camouflaged nanoparticles via bioorthogonal reactions for improving drug leads capturing. Acta Pharm Sin B 2023; 13:852-862. [PMID: 36873174 PMCID: PMC9979189 DOI: 10.1016/j.apsb.2022.05.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 04/04/2022] [Accepted: 05/17/2022] [Indexed: 11/24/2022] Open
Abstract
Cell membrane camouflaged nanoparticles have been widely used in the field of drug leads discovery attribute to their unique biointerface targeting function. However, random orientation of cell membrane coating does not guarantee effective and appropriate binding of drugs to specific sites, especially when applied to intracellular regions of transmembrane proteins. Bioorthogonal reactions have been rapidly developed as a specific and reliable method for cell membrane functionalization without disturbing living biosystem. Herein, inside-out cell membrane camouflaged magnetic nanoparticles (IOCMMNPs) were accurately constructed via bioorthogonal reactions to screen small molecule inhibitors targeting intracellular tyrosine kinase domain of vascular endothelial growth factor recptor-2. Azide functionalized cell membrane acted as a platform for specific covalently coupling with alkynyl functionalized magnetic Fe3O4 nanoparticles to prepare IOCMMNPs. The inside-out orientation of cell membrane was successfully verified by immunogold staining and sialic acid quantification assay. Ultimately, two compounds, senkyunolide A and ligustilidel, were successfully captured, and their potential antiproliferative activities were further testified by pharmacological experiments. It is anticipated that the proposed inside-out cell membrane coating strategy endows tremendous versatility for engineering cell membrane camouflaged nanoparticles and promotes the development of drug leads discovery platforms.
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8
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Basu D, Pal R, Sarkar M, Barma S, Halder S, Roy H, Nandi S, Samadder A. To Investigate Growth Factor Receptor Targets and Generate Cancer Targeting Inhibitors. Curr Top Med Chem 2023; 23:2877-2972. [PMID: 38164722 DOI: 10.2174/0115680266261150231110053650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 09/20/2023] [Accepted: 10/02/2023] [Indexed: 01/03/2024]
Abstract
Receptor tyrosine kinase (RTK) regulates multiple pathways, including Mitogenactivated protein kinases (MAPKs), PI3/AKT, JAK/STAT pathway, etc. which has a significant role in the progression and metastasis of tumor. As RTK activation regulates numerous essential bodily processes, including cell proliferation and division, RTK dysregulation has been identified in many types of cancers. Targeting RTK is a significant challenge in cancer due to the abnormal upregulation and downregulation of RTK receptors subfamily EGFR, FGFR, PDGFR, VEGFR, and HGFR in the progression of cancer, which is governed by multiple RTK receptor signalling pathways and impacts treatment response and disease progression. In this review, an extensive focus has been carried out on the normal and abnormal signalling pathways of EGFR, FGFR, PDGFR, VEGFR, and HGFR and their association with cancer initiation and progression. These are explored as potential therapeutic cancer targets and therefore, the inhibitors were evaluated alone and merged with additional therapies in clinical trials aimed at combating global cancer.
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Affiliation(s)
- Debroop Basu
- Cell and Developmental Biology Special, Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, India
| | - Riya Pal
- Cell and Developmental Biology Special, Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, IndiaIndia
| | - Maitrayee Sarkar
- Cell and Developmental Biology Special, Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, India
| | - Soubhik Barma
- Cell and Developmental Biology Special, Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, India
| | - Sumit Halder
- Cell and Developmental Biology Special, Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, India
| | - Harekrishna Roy
- Nirmala College of Pharmacy, Vijayawada, Guntur, Andhra Pradesh, India
| | - Sisir Nandi
- Global Institute of Pharmaceutical Education and Research (Affiliated to Uttarakhand Technical University), Kashipur, 244713, India
| | - Asmita Samadder
- Cell and Developmental Biology Special, Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, India
- Cytogenetics and Molecular Biology Lab., Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, India
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9
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Zapata-Mercado E, Biener G, McKenzie DM, Wimley WC, Pasquale EB, Raicu V, Hristova K. The efficacy of receptor tyrosine kinase EphA2 autophosphorylation increases with EphA2 oligomer size. J Biol Chem 2022; 298:102370. [PMID: 35970390 PMCID: PMC9512837 DOI: 10.1016/j.jbc.2022.102370] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/30/2022] Open
Abstract
The receptor tyrosine kinase (RTK) EphA2 is expressed in epithelial and endothelial cells and controls the assembly of cell-cell junctions. EphA2 has also been implicated in many diseases, including cancer. Unlike most RTKs, which signal predominantly as dimers, EphA2 readily forms high-order oligomers upon ligand binding. Here, we investigated if a correlation exists between EphA2 signaling properties and the size of the EphA2 oligomers induced by multiple ligands, including the widely used ephrinA1-Fc ligand, the soluble monomeric m-ephrinA1, and novel engineered peptide ligands. We used fluorescence intensity fluctuation (FIF) spectrometry to characterize the EphA2 oligomer populations induced by the different ligands. Interestingly, we found that different monomeric and dimeric ligands induce EphA2 oligomers with widely different size distributions. Our comparison of FIF brightness distribution parameters and EphA2 signaling parameters reveals that the efficacy of EphA2 phosphorylation on tyrosine 588, an autophosphorylation response contributing to EphA2 activation, correlates with EphA2 mean oligomer size. However, we found that other characteristics, such as the efficacy of AKT inhibition and ligand bias coefficients, appear to be independent of EphA2 oligomer size. Taken together, this work highlights the utility of FIF in RTK signaling research and demonstrates a quantitative correlation between the architecture of EphA2 signaling complexes and signaling features.
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Affiliation(s)
- Elmer Zapata-Mercado
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Gabriel Biener
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin, USA
| | - Daniel M McKenzie
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - William C Wimley
- Tulane University School of Medicine, Department of Biochemistry and Molecular Biology, New Orleans, Louisiana, USA
| | - Elena B Pasquale
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA.
| | - Valerica Raicu
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin, USA; Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, USA.
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
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10
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Wirth D, Paul MD, Pasquale EB, Hristova K. Direct quantification of ligand-induced lipid and protein microdomains with distinctive signaling properties. CHEMSYSTEMSCHEM 2022; 4:e202200011. [PMID: 36337751 PMCID: PMC9634703 DOI: 10.1002/syst.202200011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Indexed: 11/08/2022]
Abstract
Lipid rafts are ordered lipid domains that are enriched in saturated lipids, such as the ganglioside GM1. While lipid rafts are believed to exist in cells and to serve as signaling platforms through their enrichment in signaling components, they have not been directly observed in the plasma membrane without treatments that artificially cluster GM1 into large lattices. Here, we report that microscopic GM1-enriched domains can form, in the plasma membrane of live mammalian cells expressing the EphA2 receptor tyrosine kinase in response to its ligand ephrinA1-Fc. The GM1-enriched microdomains form concomitantly with EphA2-enriched microdomains. To gain insight into how plasma membrane heterogeneity controls signaling, we quantify the degree of EphA2 segregation and study initial EphA2 signaling steps in both EphA2-enriched and EphA2-depleted domains. By measuring dissociation constants, we demonstrate that the propensity of EphA2 to oligomerize is similar in EphA2-enriched and -depleted domains. However, surprisingly, EphA2 interacts preferentially with its downstream effector SRC in EphA2-depleted domains. The ability to induce microscopic GM1-enriched domains in live cells using a ligand for a transmembrane receptor will give us unprecedented opportunities to study the biophysical chemistry of lipid rafts.
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Affiliation(s)
- Daniel Wirth
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
| | - Michael D. Paul
- Program in Molecular Biophysics, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
| | - Elena B. Pasquale
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Road, La Jolla, CA 92037
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
- Program in Molecular Biophysics, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
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11
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Ornitz DM, Itoh N. New developments in the biology of fibroblast growth factors. WIREs Mech Dis 2022; 14:e1549. [PMID: 35142107 PMCID: PMC10115509 DOI: 10.1002/wsbm.1549] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 01/28/2023]
Abstract
The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.
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Affiliation(s)
- David M Ornitz
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nobuyuki Itoh
- Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
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12
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Quantitative characterization of tetraspanin 8 homointeractions in the plasma membrane. Biochem J 2021; 478:3643-3654. [PMID: 34524408 DOI: 10.1042/bcj20210459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 11/17/2022]
Abstract
The spatial distribution of proteins in cell membranes is crucial for signal transduction, cell communication and membrane trafficking. Members of the Tetraspanin family organize functional protein clusters within the plasma membrane into so-called Tetraspanin-enriched microdomains (TEMs). Direct interactions between Tetraspanins are believed to be important for this organization. However, studies thus far have utilized mainly co-immunoprecipitation methods that cannot distinguish between direct and indirect, through common partners, interactions. Here we study Tetraspanin 8 homointeractions in living cells via quantitative fluorescence microscopy. We demonstrate that Tetraspanin 8 exists in a monomer-dimer equilibrium in the plasma membrane. Tetraspanin 8 dimerization is described by a high dissociation constant (Kd = 14 700 ± 1100 Tspan8/µm2), one of the highest dissociation constants measured for membrane proteins in live cells. We propose that this high dissociation constant, and thus the short lifetime of the Tetraspanin 8 dimer, is critical for Tetraspanin 8 functioning as a master regulator of cell signaling.
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13
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Kadry YA, Lee JY, Witze ES. Regulation of EGFR signalling by palmitoylation and its role in tumorigenesis. Open Biol 2021; 11:210033. [PMID: 34610265 PMCID: PMC8492172 DOI: 10.1098/rsob.210033] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The epidermal growth factor receptor (EGFR) is an essential driver of oncogenic signalling, and EGFR inhibitors are some of the earliest examples of successful targeted therapies in multiple types of cancer. The tractability of EGFR as a therapeutic target is overshadowed by the inevitable drug resistance that develops. Overcoming resistance mechanisms requires a deeper understanding of EGFR regulation in cancer cells. In this review, we discuss our recent discovery that the palmitoyltransferase DHHC20 palmitoylates EGFR on the C-terminal domain and plays a critical role in signal regulation during oncogenesis. Inhibiting DHHC20 expression or mutating the palmitoylation site on EGFR alters the EGF-induced signalling kinetics from a transient signal to a sustained signal. The change in signalling is accompanied by a decrease in cell proliferation in multiple human cancer cell lines. Our in vivo studies demonstrate that ablating the gene Zdhhc20 by CRISPR/Cas9-mediated inhibition in a mouse model of oncogenic Kras-driven lung adenocarcinoma potently inhibits tumorigenesis. The negative effect on tumorigenesis is mediated by EGFR since the expression of a palmitoylation-resistant mutant form of EGFR also inhibits Kras-driven lung adenocarcinoma. Finally, reducing EGFR palmitoylation increases the sensitivity of multiple cancer cell lines to existing inhibitors of EGFR and downstream signalling effector pathways. We will discuss the implications of these effects and strategies for targeting these new vulnerabilities.
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Affiliation(s)
- Yasmin A. Kadry
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jia-Ying Lee
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eric S. Witze
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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14
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Franco ML, Nadezhdin KD, Light TP, Goncharuk SA, Soler-Lopez A, Ahmed F, Mineev KS, Hristova K, Arseniev AS, Vilar M. Interaction between the transmembrane domains of neurotrophin receptors p75 and TrkA mediates their reciprocal activation. J Biol Chem 2021; 297:100926. [PMID: 34216618 PMCID: PMC8327350 DOI: 10.1016/j.jbc.2021.100926] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/25/2021] [Accepted: 06/28/2021] [Indexed: 11/23/2022] Open
Abstract
The neurotrophin receptors p75 and tyrosine protein kinase receptor A (TrkA) play important roles in the development and survival of the nervous system. Biochemical data suggest that p75 and TrkA reciprocally regulate the activities of each other. For instance, p75 is able to regulate the response of TrkA to lower concentrations of nerve growth factor (NGF), and TrkA promotes shedding of the extracellular domain of p75 by α-secretases in a ligand-dependent manner. The current model suggests that p75 and TrkA are regulated by means of a direct physical interaction; however, the nature of such interaction has been elusive thus far. Here, using NMR in micelles, multiscale molecular dynamics, FRET, and functional studies, we identified and characterized the direct interaction between TrkA and p75 through their respective transmembrane domains (TMDs). Molecular dynamics of p75-TMD mutants suggests that although the interaction between TrkA and p75 TMDs is maintained upon mutation, a specific protein interface is required to facilitate TrkA active homodimerization in the presence of NGF. The same mutations in the TMD protein interface of p75 reduced the activation of TrkA by NGF as well as reducing cell differentiation. In summary, we provide a structural model of the p75-TrkA receptor complex necessary for neuronal development stabilized by TMD interactions.
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Affiliation(s)
- María L Franco
- Unit of Molecular Basis of Neurodegeneration, Institute of Biomedicine CSIC, València, Spain
| | - Kirill D Nadezhdin
- Department of Structural Biology, Laboratory of NMR-Spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russian Federation
| | - Taylor P Light
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Sergey A Goncharuk
- Department of Structural Biology, Laboratory of NMR-Spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russian Federation; Phystech School of Biological and Medical Physics, Moscow Institute of Physics and Technology, Moscow, Russian Federation
| | - Andrea Soler-Lopez
- Unit of Molecular Basis of Neurodegeneration, Institute of Biomedicine CSIC, València, Spain
| | - Fozia Ahmed
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Konstantin S Mineev
- Department of Structural Biology, Laboratory of NMR-Spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russian Federation; Phystech School of Biological and Medical Physics, Moscow Institute of Physics and Technology, Moscow, Russian Federation
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Alexander S Arseniev
- Department of Structural Biology, Laboratory of NMR-Spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russian Federation.
| | - Marçal Vilar
- Unit of Molecular Basis of Neurodegeneration, Institute of Biomedicine CSIC, València, Spain.
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15
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Lambrou GI, Karakonstantakis T, Vlahopoulos S, Zaravinos A. Dual Mechanisms of Metabolism and Gene Expression of the CCRF-CEM Leukemia Cells under Glucocorticoid Treatment. Int J Mol Sci 2021; 22:ijms22115889. [PMID: 34072627 PMCID: PMC8198442 DOI: 10.3390/ijms22115889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/25/2020] [Accepted: 10/26/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Glucocorticoids play an essential part in anti-leukemic therapies, but resistance is a crucial event for the prognosis of the disease. Glucocorticoids influence the metabolic properties of leukemic cells. The inherent plasticity of clinically evolving cancer cells justifies the characterization of drug-induced early oncogenic pathways, which represent a likely source of detrimental secondary effects. AIM The present work aims to investigate the effect of glucocorticoids in metabolic pathways in the CCRF-CEM leukemic cells. Metabolic factors and gene expression profiles were examined in order to unravel the possible mechanisms of the CCRF-CEM leukemic cell growth dynamics. METHODS CCRF-CEM cells were used as a model. Cells were treated with prednisolone with concentrations 0-700 μM. Cell culture supernatants were used for glucose, lactic acid, LDH, Na+, K+ and Ca++ measurements. Cytotoxicity was determined with flow cytometry. Microarray analysis was performed using two different chips of 1.2 k and 4.8 k genes. Gene Ontology enrichment analysis was applied to find metabolism- and GC-related genes. RESULTS Higher prednisolone concentrations inhibited glucose uptake, without exhibiting any cytotoxic effects. Glucose consumption did not correlate with the total cell population, or the viable population, indicating that growth is not directly proportional to glucose consumption. Neither of the subpopulations, i.e., viable, necrotic, or apoptotic cells, contributed to this. CONCLUSIONS Different types of leukemic cells seem to exhibit different patterns of glucose metabolism. Both resistant and sensitive CCRF-CEM cells followed the aerobic pathway of glycolysis. There is probably a rapid change in membrane permeability, causing a general shutdown towards everything that is outside the cell. This could in part also explain the observed resistance. Glucocorticoids do not enter the cell passively anymore and therefore no effects are observed. Based on our observations, ion concentrations are measurable factors both in vitro and in vivo, which makes them possible markers of glucocorticoid cytotoxic action.
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Affiliation(s)
- George I. Lambrou
- Choremeio Research Laboratory, First Department of Pediatrics, National and Kapodistrian University of Athens, Thivon & Levadeias 8, Goudi, 11527 Athens, Greece;
- Correspondence: (G.I.L.); (A.Z.); Tel.: +30-210-746-7427 (G.I.L.)
| | | | - Spiros Vlahopoulos
- Choremeio Research Laboratory, First Department of Pediatrics, National and Kapodistrian University of Athens, Thivon & Levadeias 8, Goudi, 11527 Athens, Greece;
| | - Apostolos Zaravinos
- Department of Life Sciences, School of Sciences, European University Cyprus, 1516 Nicosia, Cyprus
- Correspondence: (G.I.L.); (A.Z.); Tel.: +30-210-746-7427 (G.I.L.)
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16
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Ferguson HR, Smith MP, Francavilla C. Fibroblast Growth Factor Receptors (FGFRs) and Noncanonical Partners in Cancer Signaling. Cells 2021; 10:1201. [PMID: 34068954 PMCID: PMC8156822 DOI: 10.3390/cells10051201] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/06/2021] [Accepted: 05/09/2021] [Indexed: 02/07/2023] Open
Abstract
Increasing evidence indicates that success of targeted therapies in the treatment of cancer is context-dependent and is influenced by a complex crosstalk between signaling pathways and between cell types in the tumor. The Fibroblast Growth Factor (FGF)/FGF receptor (FGFR) signaling axis highlights the importance of such context-dependent signaling in cancer. Aberrant FGFR signaling has been characterized in almost all cancer types, most commonly non-small cell lung cancer (NSCLC), breast cancer, glioblastoma, prostate cancer and gastrointestinal cancer. This occurs primarily through amplification and over-expression of FGFR1 and FGFR2 resulting in ligand-independent activation. Mutations and translocations of FGFR1-4 are also identified in cancer. Canonical FGF-FGFR signaling is tightly regulated by ligand-receptor combinations as well as direct interactions with the FGFR coreceptors heparan sulfate proteoglycans (HSPGs) and Klotho. Noncanonical FGFR signaling partners have been implicated in differential regulation of FGFR signaling. FGFR directly interacts with cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins, contributing to invasive and migratory properties of cancer cells, whereas interactions with other receptor tyrosine kinases (RTKs) regulate angiogenic, resistance to therapy, and metastatic potential of cancer cells. The diversity in FGFR signaling partners supports a role for FGFR signaling in cancer, independent of genetic aberration.
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Affiliation(s)
- Harriet R. Ferguson
- Division of Molecular and Cellular Function, School of Biological Science, Faculty of Biology Medicine and Health (FBMH), The University of Manchester, Manchester M13 9PT, UK;
| | - Michael P. Smith
- Division of Molecular and Cellular Function, School of Biological Science, Faculty of Biology Medicine and Health (FBMH), The University of Manchester, Manchester M13 9PT, UK;
| | - Chiara Francavilla
- Division of Molecular and Cellular Function, School of Biological Science, Faculty of Biology Medicine and Health (FBMH), The University of Manchester, Manchester M13 9PT, UK;
- Manchester Breast Centre, Manchester Cancer Research Centre, The University of Manchester, Manchester M20 4GJ, UK
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17
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Interactions between Ligand-Bound EGFR and VEGFR2. J Mol Biol 2021; 433:167006. [PMID: 33891904 DOI: 10.1016/j.jmb.2021.167006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/25/2021] [Accepted: 04/15/2021] [Indexed: 11/21/2022]
Abstract
In this work, we put forward the provocative hypothesis that the active, ligand-bound RTK dimers from unrelated subfamilies can associate into heterooligomers with novel signaling properties. This hypothesis is based on a quantitative FRET study that monitors the interactions between EGFR and VEGFR2 in the plasma membrane of live cells in the absence of ligand, in the presence of either EGF or VEGF, and in the presence of both ligands. We show that direct interactions occur between EGFR and VEGFR2 in the absence of ligand and in the presence of the two cognate ligands. However, there are not significant heterointeractions between EGFR and VEGFR2 when only one of the ligands is present. Since RTK dimers and RTK oligomers are believed to signal differently, this finding suggests a novel mechanism for signal diversification.
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18
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Paul MD, Rainwater R, Zuo Y, Gu L, Hristova K. Probing Membrane Protein Association Using Concentration‐Dependent Number and Brightness. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202010049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michael D. Paul
- Program in Molecular Biophysics Johns Hopkins University Baltimore MD 21218 USA
| | - Randall Rainwater
- Department of Materials Science and Engineering and Institute for NanoBioTechnology Johns Hopkins University Baltimore MD 21218 USA
| | - Yi Zuo
- Department of Materials Science and Engineering and Institute for NanoBioTechnology Johns Hopkins University Baltimore MD 21218 USA
| | - Luo Gu
- Department of Materials Science and Engineering and Institute for NanoBioTechnology Johns Hopkins University Baltimore MD 21218 USA
| | - Kalina Hristova
- Department of Materials Science and Engineering and Institute for NanoBioTechnology Johns Hopkins University Baltimore MD 21218 USA
- Program in Molecular Biophysics Johns Hopkins University Baltimore MD 21218 USA
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19
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Analysis of transient membrane protein interactions by single-molecule diffusional mobility shift assay. Exp Mol Med 2021; 53:291-299. [PMID: 33603128 PMCID: PMC8080847 DOI: 10.1038/s12276-021-00567-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/29/2020] [Accepted: 01/06/2021] [Indexed: 01/31/2023] Open
Abstract
Various repertoires of membrane protein interactions determine cellular responses to diverse environments around cells dynamically in space and time. Current assays, however, have limitations in unraveling these interactions in the physiological states in a living cell due to the lack of capability to probe the transient nature of these interactions on the crowded membrane. Here, we present a simple and robust assay that enables the investigation of transient protein interactions in living cells by using the single-molecule diffusional mobility shift assay (smDIMSA). Utilizing smDIMSA, we uncovered the interaction profile of EGFR with various membrane proteins and demonstrated the promiscuity of these interactions depending on the cancer cell line. The transient interaction profile obtained by smDIMSA will provide critical information to comprehend the crosstalk among various receptors on the plasma membrane.
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20
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Paul MD, Rainwater R, Zuo Y, Gu L, Hristova K. Probing Membrane Protein Association Using Concentration-Dependent Number and Brightness. Angew Chem Int Ed Engl 2021; 60:6503-6508. [PMID: 33351993 DOI: 10.1002/anie.202010049] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 11/11/2020] [Indexed: 01/13/2023]
Abstract
We introduce concentration-dependent number and brightness (cdN&B), a fluorescence fluctuation technique that can be implemented on a standard confocal microscope and can report on the thermodynamics of membrane protein association in the native plasma membrane. It uses transient transfection to enable measurements of oligomer size as a function of receptor concentration over a broad range, yielding the association constant. We discuss artifacts in cdN&B that are concentration-dependent and can distort the oligomerization curves, and we outline procedures that can correct for them. Using cdN&B, we characterize the association of neuropilin 1 (NRP1), a protein that plays a critical role in the development of the embryonic cardiovascular and nervous systems. We show that NRP1 associates into a tetramer in a concentration-dependent manner, and we quantify the strength of the association. This work demonstrates the utility of cdN&B as a powerful tool in biophysical chemistry.
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Affiliation(s)
- Michael D Paul
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Randall Rainwater
- Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Yi Zuo
- Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Luo Gu
- Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Kalina Hristova
- Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218, USA.,Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
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21
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Kilpatrick LE, Hill SJ. Transactivation of G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs): Recent insights using luminescence and fluorescence technologies. CURRENT OPINION IN ENDOCRINE AND METABOLIC RESEARCH 2021; 16:102-112. [PMID: 33748531 PMCID: PMC7960640 DOI: 10.1016/j.coemr.2020.10.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alterations in signalling due to bidirectional transactivation of G protein-coupled receptor (GPCRs) and receptor tyrosine kinases (RTKs) are well established. Transactivation significantly diversifies signalling networks within a cell and has been implicated in promoting both advantageous and disadvantageous physiological and pathophysiological outcomes, making the GPCR/RTK interactions attractive new targets for drug discovery programmes. Transactivation has been observed for a plethora of receptor pairings in multiple cell types; however, the precise molecular mechanisms and signalling effectors involved can vary with receptor pairings and cell type. This short review will discuss the recent applications of proximity-based assays, such as resonance energy transfer and fluorescence-based imaging in investigating the dynamics of GPCR/RTK complex formation, subsequent effector protein recruitment and the cellular locations of complexes in living cells.
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Key Words
- 5-hydroxytryptamine receptor 1A, (5-HT1A)
- Endocytosis
- Förster Resonance Energy Transfer, (FRET)
- G protein-coupled receptor
- G protein-coupled receptors, (GPCRs)
- GPCR kinases, (GRKs)
- Oligomeric complexes
- Receptor tyrosine kinase
- Resonance energy transfer
- Transactivation
- adrenoceptors, (AR)
- bioluminescence resonance energy transfer, (BRET)
- cannabinoid receptor 2, (CB2R)
- disintegrin and metalloproteinases, (ADAMs)
- epidermal growth factor receptor, (EGFR)
- epidermal growth factor, (EGF)
- fibroblast growth factor receptor, (FGFR)
- fluorescence correlation spectroscopy, (FCS)
- formyl peptide receptor, (FPR)
- free fatty acid, (FFA)
- heparin binding EGF, (Hb-EGF)
- hepatocyte growth factor, (HGF)
- human umbilical vein endothelial cells, (HUVECs)
- insulin growth factor receptor-1, (IGFR-1)
- insulin receptor, (IR)
- lysophosphatidic acid receptor 1, (LPA)
- matrix metalloproteinases, (MMPs)
- platelet-derived growth factor receptor, (PDGFR)
- proximity ligation assay, (PLA)
- reactive oxygen species, (ROS)
- receptor tyrosine kinases, (RTKs)
- sphingosine-1-phosphate receptor, (S1PR)
- tetrahydrocannabinol, (THC)
- total internal reflection fluorescence microscopy, (TIRF-M)
- vascular endothelial growth factor receptor 2, (VEGFR2)
- vascular endothelial growth factor, (VEGF)
- vasopressin 2 receptor, (V2R)
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Affiliation(s)
- Laura E. Kilpatrick
- Division of Bimolecular Sciences and Medicinal Chemistry, Biodiscovery Institute, School of Pharmacy, University of Nottingham, Nottingham, NG7 2RD, UK
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, NG7 2UH, UK
| | - Stephen J. Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, NG7 2UH, UK
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22
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Ahmed F, Zapata-Mercado E, Rahman S, Hristova K. The Biased Ligands NGF and NT-3 Differentially Stabilize Trk-A Dimers. Biophys J 2020; 120:55-63. [PMID: 33285113 DOI: 10.1016/j.bpj.2020.11.2262] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/14/2020] [Accepted: 11/23/2020] [Indexed: 12/23/2022] Open
Abstract
Trk-A is a receptor tyrosine kinase (RTK) that plays an essential role in the development and functioning of the nervous system. Trk-A is expressed in neurons and signals in response to two ligands, NGF and neurotrophin-3 (NT-3), with very different functional consequences. Thus, NGF and NT-3 are "biased" ligands for Trk-A. Because it has been hypothesized that biased RTK ligands induce differential stabilization of RTK dimers, here, we seek to test this hypothesis for NGF and NT-3. In particular, we use Förster resonance energy transfer (FRET) and fluorescence intensity fluctuation spectroscopy to assess the strength of Trk-A interactions and Trk-A oligomer size in the presence of the two ligands. Although the difference in Trk-A behavior in response to the two ligands has been previously attributed to differences in their binding to Trk-A in the endosomes at low pH, here, we further show differences in the stabilities of the NGF- and NT-3-bound Trk-A dimers in the plasma membrane and at neutral pH. We discuss the biological significance of these new findings and their implications for the design of Trk-A ligands with novel functionalities.
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Affiliation(s)
- Fozia Ahmed
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland; Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland
| | - Elmer Zapata-Mercado
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland; Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland
| | - Sanim Rahman
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland; Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland; Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland.
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