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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 2024:107441. [PMID: 38838777 DOI: 10.1016/j.jbc.2024.107441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [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 associate 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 stability 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, 3400 Charles Street, Baltimore, MD 21218
| | - Ece Özdemir
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
| | - William C Wimley
- Tulane University School of Medicine, Department of Biochemistry and Molecular Biology, New Orleans, LA
| | - 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;.
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Abouelkheir M, Roy T, Krzyscik MA, Özdemir E, Hristova K. Investigations of membrane protein interactions in cells using fluorescence microscopy. Curr Opin Struct Biol 2024; 86:102816. [PMID: 38648680 PMCID: PMC11141325 DOI: 10.1016/j.sbi.2024.102816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/06/2024] [Accepted: 03/26/2024] [Indexed: 04/25/2024]
Abstract
The interactions between proteins in membranes govern many cellular functions. Our ability to probe for such interactions has greatly evolved in recent years due to the introduction of new fluorescence techniques. As a result, we currently have a choice of methods that can be used to assess the spatial distribution of a membrane protein, its association state, and the thermodynamic stability of the oligomers in the native milieu. These biophysical measurements have revealed new insights into important biological processes in cellular membranes.
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Affiliation(s)
- Mahmoud Abouelkheir
- Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore MD 21218, USA; Chemistry-Biology Interface Program, Johns Hopkins University, Baltimore MD 21218, USA
| | - Tanaya Roy
- Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore MD 21218, USA
| | - Mateusz A Krzyscik
- Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore MD 21218, USA
| | - Ece Özdemir
- 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; Chemistry-Biology Interface Program, Johns Hopkins University, Baltimore MD 21218, USA.
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Kottom TJ, Carmona EM, Limper AH. Targeting host tyrosine kinase receptor EphA2 signaling via small-molecule ALW-II-41-27 inhibits macrophage pro-inflammatory signaling responses to Pneumocystis carinii β-glucans. Antimicrob Agents Chemother 2024; 68:e0081123. [PMID: 38206037 PMCID: PMC10848750 DOI: 10.1128/aac.00811-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 12/03/2023] [Indexed: 01/12/2024] Open
Abstract
Pneumocystis jirovecii, the fungus that causes Pneumocystis jirovecii pneumonia (PJP), is a leading cause of morbidity and mortality in immunocompromised individuals. We have previously shown that lung epithelial cells can bind Pneumocystis spp. β-glucans via the EphA2 receptor, resulting in activation and release of proinflammatory cytokines. Herein, we show that in vivo Pneumocystis spp. β-glucans activation of the inflammatory signaling cascade in macrophages can be pharmacodynamically inhibited with the EphA2 receptor small-molecule inhibitor ALW-II-41-27. In vitro, when ALW-II-41-27 is administrated via intraperitoneal to mice prior to the administration of highly proinflammatory Saccharomyces cerevisiae β-glucans in the lung, a significant reduction in TNF-alpha release was noted in the ALW-II-41-27 pre-treated group. Taken together, our data suggest that targeting host lung macrophage activation via EphA2 receptor-fungal β-glucans interactions with ALW-II-41-27 or other EphA2 receptor kinase targeting inhibitors might be an attractive and viable strategy to reduce detrimental lung inflammation associated with PJP.
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Affiliation(s)
- Theodore J. Kottom
- Departments of Medicine and Biochemistry, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
- Thoracic Diseases Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Eva M. Carmona
- Departments of Medicine and Biochemistry, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
- Thoracic Diseases Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Andrew H. Limper
- Departments of Medicine and Biochemistry, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
- Thoracic Diseases Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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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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Primeaux M, Liu X, Gowrikumar S, Fatima I, Fisher KW, Bastola D, Vecchio AJ, Singh AB, Dhawan P. Claudin-1 interacts with EPHA2 to promote cancer stemness and chemoresistance in colorectal cancer. Cancer Lett 2023; 579:216479. [PMID: 37924938 PMCID: PMC10765961 DOI: 10.1016/j.canlet.2023.216479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/12/2023] [Accepted: 10/29/2023] [Indexed: 11/06/2023]
Abstract
Therapy resistance is the primary problem in treating late-stage colorectal cancer (CRC). Claudins are frequently dysregulated in cancer, and several are being investigated as novel therapeutic targets and biomarkers. We have previously demonstrated that Claudin-1 (CLDN1) expression in CRC promotes epithelial-mesenchymal transition, metastasis, and resistance to anoikis. Here, we hypothesize that CLDN1 promotes cancer stemness and chemoresistance in CRC. We found that high CLDN1 expression in CRC is associated with cancer stemness and chemoresistance signaling pathways in patient datasets, and it promotes chemoresistance both in vitro and in vivo. Using functional stemness assays, proteomics, biophysical binding assays, and patient-derived organoids, we found that CLDN1 promotes properties of cancer stemness including CD44 expression, tumor-initiating potential, and chemoresistance through a direct interaction with ephrin type-A receptor 2 (EPHA2) tyrosine kinase. This interaction is dependent on the CLDN1 PDZ-binding motif, increases EPHA2 protein expression by inhibiting its degradation, and enhances downstream AKT signaling and CD44 expression to promote stemness and chemoresistance. These results suggest CLDN1 is a viable target for pharmacological intervention and/or biomarker development.
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Affiliation(s)
- Mark Primeaux
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Xiangdong Liu
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Saiprasad Gowrikumar
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Iram Fatima
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Kurt W Fisher
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Dhundy Bastola
- Department of Bioinformatics, University of Nebraska Omaha, Omaha, NE, USA
| | - Alex J Vecchio
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Amar B Singh
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA; Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA; VA Nebraska-Western Iowa Health Care System, Omaha, NE, USA
| | - Punita Dhawan
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA; Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA; VA Nebraska-Western Iowa Health Care System, Omaha, NE, USA.
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McKenzie DM, Wirth D, Pogorelov TV, Hristova K. Utility of FRET in studies of membrane protein oligomerization: The concept of the effective dissociation constant. Biophys J 2023; 122:4113-4120. [PMID: 37735871 PMCID: PMC10598290 DOI: 10.1016/j.bpj.2023.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/07/2023] [Accepted: 09/18/2023] [Indexed: 09/23/2023] Open
Abstract
The activity of many membrane receptors is controlled through their lateral association into dimers or higher-order oligomers. Although Förster resonance energy transfer (FRET) measurements have been used extensively to characterize the stability of receptor dimers, the utility of FRET in studies of larger oligomers has been limited. Here we introduce an effective equilibrium dissociation constant that can be extracted from FRET measurements for EphA2, a receptor tyrosine kinase (RTK) known to form active oligomers of heterogeneous distributions in response to its ligand ephrinA1-Fc. The newly introduced effective equilibrium dissociation constant has a well-defined physical meaning and biological significance. It denotes the receptor concentration for which half of the receptors are monomeric and inactive, and the other half are associated into oligomers and are active, irrespective of the exact oligomer size. This work introduces a new dimension to the utility of FRET in studies of membrane receptor association and signaling in the plasma membrane.
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Affiliation(s)
- Daniel M McKenzie
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, Maryland
| | - Daniel Wirth
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, Maryland
| | - Taras V Pogorelov
- Department of Chemistry, Center for Biophysics and Quantitative Biology, School of Chemical Sciences, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, Maryland.
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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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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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