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Mudumbi KC, Burns EA, Schodt DJ, Petrova ZO, Kiyatkin A, Kim LW, Mangiacapre EM, Ortiz-Caraveo I, Rivera Ortiz H, Hu C, Ashtekar KD, Lidke KA, Lidke DS, Lemmon MA. Distinct interactions stabilize EGFR dimers and higher-order oligomers in cell membranes. Cell Rep 2024; 43:113603. [PMID: 38117650 PMCID: PMC10835193 DOI: 10.1016/j.celrep.2023.113603] [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: 06/23/2023] [Revised: 09/23/2023] [Accepted: 12/05/2023] [Indexed: 12/22/2023] Open
Abstract
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase with important roles in many cellular processes as well as in cancer and other diseases. EGF binding promotes EGFR dimerization and autophosphorylation through interactions that are well understood structurally. How these dimers relate to higher-order EGFR oligomers seen in cell membranes, however, remains unclear. Here, we used single-particle tracking (SPT) and Förster resonance energy transfer imaging to examine how each domain of EGFR contributes to receptor oligomerization and the rate of receptor diffusion in the cell membrane. Although the extracellular region of EGFR is sufficient to drive receptor dimerization, we find that the EGF-induced EGFR slowdown seen by SPT requires higher-order oligomerization-mediated in part by the intracellular tyrosine kinase domain when it adopts an active conformation. Our data thus provide important insight into the interactions required for higher-order EGFR assemblies involved in EGF signaling.
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Affiliation(s)
- Krishna C Mudumbi
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA.
| | - Eric A Burns
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - David J Schodt
- Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA; Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87106, USA
| | - Zaritza O Petrova
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Anatoly Kiyatkin
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Lucy W Kim
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Emma M Mangiacapre
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Irais Ortiz-Caraveo
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Hector Rivera Ortiz
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Chun Hu
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Kumar D Ashtekar
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Keith A Lidke
- Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA; Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87106, USA
| | - Diane S Lidke
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.
| | - Mark A Lemmon
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA; Yale Cancer Biology Institute, Yale University West Campus, West Haven, CT 06516, USA.
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Clayton AHA. Spectral Relaxation Imaging Microscopy II: Complex Dynamics. Int J Mol Sci 2023; 24:12271. [PMID: 37569641 PMCID: PMC10419246 DOI: 10.3390/ijms241512271] [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: 07/05/2023] [Revised: 07/18/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
The dynamics of condensed matter can be measured by the time-dependent Stokes shift of a suitable fluorescent probe. The time-dependent spectral correlation function is typically described by one or more spectral relaxation correlation times, which, in liquid solvents, characterize the timescales of the dipolar relaxation processes around the excited-state probe. The phasor plot provides a powerful approach to represent and analyze time and frequency-domain data acquired as images, thus providing a spatial map of spectral dynamics in a complex structure such as a living cell. Measurements of the phase and modulation at two emission wavelength channels were shown to be sufficient to extract a single excited-state lifetime and a single spectral relaxation correlation time, supplying estimates of the mean rate of excited-state depopulation and the mean rate of spectral shift. In the present contribution, two more issues were addressed. First, the provision of analytic formulae allowing extraction of the initial generalized polarization and the relaxed generalized polarization, which characterize the fluorescence spectrum of the unrelaxed state and the fully relaxed state. Second, improved methods of model discrimination and model parameter extraction for more complex spectral relaxation phenomena. The analysis workflow was illustrated with examples from the literature.
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Affiliation(s)
- Andrew H A Clayton
- Cell Biophysics Laboratory, Department of Physics and Astronomy, Optical Sciences Centre, School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Melbourne 3122, Australia
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Mudumbi KC, Burns EA, Schodt DJ, Petrova ZO, Kiyatkin A, Kim LW, Mangiacapre EM, Ortiz-Caraveo I, Ortiz HR, Hu C, Ashtekar KD, Lidke KA, Lidke DS, Lemmon MA. Distinct interactions stabilize EGFR dimers and higher-order oligomers in cell membranes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.10.536273. [PMID: 37090557 PMCID: PMC10120646 DOI: 10.1101/2023.04.10.536273] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase (RTK) with important roles in many cellular processes as well as cancer and other diseases. EGF binding promotes EGFR dimerization and autophosphorylation through interactions that are well understood structurally. However, it is not clear how these dimers relate to higher-order EGFR oligomers detected at the cell surface. We used single-particle tracking (SPT) and Förster resonance energy transfer (FRET) imaging to examine how each domain within EGFR contributes to receptor dimerization and the rate of its diffusion in the cell membrane. We show that the EGFR extracellular region is sufficient to drive receptor dimerization, but that the EGF-induced EGFR slow-down seen by SPT requires formation of higher order oligomers, mediated in part by the intracellular tyrosine kinase domain - but only when in its active conformation. Our data thus provide important insight into higher-order EGFR interactions required for EGF signaling.
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Refinement of Singer-Nicolson fluid-mosaic model by microscopy imaging: Lipid rafts and actin-induced membrane compartmentalization. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184093. [PMID: 36423676 DOI: 10.1016/j.bbamem.2022.184093] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/22/2022]
Abstract
This year celebrates the 50th anniversary of the Singer-Nicolson fluid mosaic model for biological membranes. The next level of sophistication we have achieved for understanding plasma membrane (PM) structures, dynamics, and functions during these 50 years includes the PM interactions with cortical actin filaments and the partial demixing of membrane constituent molecules in the PM, particularly raft domains. Here, first, we summarize our current knowledge of these two structures and emphasize that they are interrelated. Second, we review the structure, molecular dynamics, and function of raft domains, with main focuses on raftophilic glycosylphosphatidylinositol-anchored proteins (GPI-APs) and their signal transduction mechanisms. We pay special attention to the results obtained by single-molecule imaging techniques and other advanced microscopy methods. We also clarify the limitations of present optical microscopy methods for visualizing raft domains, but emphasize that single-molecule imaging techniques can "detect" raft domains associated with molecules of interest in the PM.
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Balasubramanian H, Sankaran J, Pandey S, Goh CJH, Wohland T. The dependence of EGFR oligomerization on environment and structure: A camera-based N&B study. Biophys J 2022; 121:4452-4466. [PMID: 36335429 PMCID: PMC9748371 DOI: 10.1016/j.bpj.2022.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
Number and brightness (N&B) analysis is a fluorescence spectroscopy technique to quantify oligomerization of the mobile fraction of proteins. Accurate results, however, rely on a good knowledge of nonfluorescent states of the fluorescent labels, especially of fluorescent proteins, which are widely used in biology. Fluorescent proteins have been characterized for confocal, but not camera-based, N&B, which allows, in principle, faster measurements over larger areas. Here, we calibrate camera-based N&B implemented on a total internal reflection fluorescence microscope for various fluorescent proteins by determining their propensity to be fluorescent. We then apply camera-based N&B in live CHO-K1 cells to determine the oligomerization state of the epidermal growth factor receptor (EGFR), a transmembrane receptor tyrosine kinase that is a crucial regulator of cell proliferation and survival with implications in many cancers. EGFR oligomerization in resting cells and its regulation by the plasma membrane microenvironment are still under debate. Therefore, we investigate the effects of extrinsic factors, including membrane organization, cytoskeletal structure, and ligand stimulation, and intrinsic factors, including mutations in various EGFR domains, on the receptor's oligomerization. Our results demonstrate that EGFR oligomerization increases with removal of cholesterol or sphingolipids or the disruption of GM3-EGFR interactions, indicating raft association. However, oligomerization is not significantly influenced by the cytoskeleton. Mutations in either I706/V948 residues or E685/E687/E690 residues in the kinase and juxtamembrane domains, respectively, lead to a decrease in oligomerization, indicating their necessity for EGFR dimerization. Finally, EGFR phosphorylation is oligomerization dependent, involving the extracellular domain (550-580 residues). Coupled with biochemical investigations, camera-based N&B indicates that EGFR oligomerization and phosphorylation are the outcomes of several molecular interactions involving the lipid content and structure of the cell membrane and multiple residues in the kinase, juxtamembrane, and extracellular domains.
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Affiliation(s)
- Harikrushnan Balasubramanian
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Jagadish Sankaran
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shambhavi Pandey
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Corinna Jie Hui Goh
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore; Department of Chemistry, National University of Singapore, Singapore, Singapore.
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