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Ragaller F, Sjule E, Urem YB, Schlegel J, El R, Urbancic D, Urbancic I, Blom H, Sezgin E. Quantifying Fluorescence Lifetime Responsiveness of Environment-Sensitive Probes for Membrane Fluidity Measurements. J Phys Chem B 2024; 128:2154-2167. [PMID: 38415644 PMCID: PMC10926104 DOI: 10.1021/acs.jpcb.3c07006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 02/08/2024] [Accepted: 02/09/2024] [Indexed: 02/29/2024]
Abstract
The structural diversity of different lipid species within the membrane defines its biophysical properties such as membrane fluidity, phase transition, curvature, charge distribution, and tension. Environment-sensitive probes, which change their spectral properties in response to their surrounding milieu, have greatly contributed to our understanding of such biophysical properties. To realize the full potential of these probes and avoid misinterpretation of their spectral responses, a detailed investigation of their fluorescence characteristics in different environments is necessary. Here, we examined the fluorescence lifetime of two newly developed membrane order probes, NR12S and NR12A, in response to alterations in their environments such as the degree of lipid saturation, cholesterol content, double bond position and configuration, and phospholipid headgroup. As a comparison, we investigated the lifetime sensitivity of the membrane tension probe Flipper in these environments. Applying fluorescence lifetime imaging microscopy (FLIM) in both model membranes and biological membranes, all probes distinguished membrane phases by lifetime but exhibited different lifetime sensitivities to varying membrane biophysical properties (e.g., cholesterol). While the lifetime of Flipper is particularly sensitive to the membrane cholesterol content, the NR12S and NR12A lifetimes are moderately sensitive to both the cholesterol content and lipid acyl chains. Moreover, all of the probes exhibit longer lifetimes at longer emission wavelengths in membranes of any complexity. This emission wavelength dependency results in varying lifetime resolutions at different spectral regions, which are highly relevant for FLIM data acquisition. Our data provide valuable insights on how to perform FLIM with these probes and highlight both their potential and limitations.
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Affiliation(s)
- Franziska Ragaller
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Ellen Sjule
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Yagmur Balim Urem
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Jan Schlegel
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Rojbin El
- Weatherall
Institute of Molecular Medicine, University
of Oxford, OX39DS Oxford, United
Kingdom
| | - Dunja Urbancic
- Weatherall
Institute of Molecular Medicine, University
of Oxford, OX39DS Oxford, United
Kingdom
- Faculty
of Pharmacy, University
of Ljubljana, 1000 Ljubljana, Slovenia
| | - Iztok Urbancic
- Laboratory
of Biophysics, Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia
| | - Hans Blom
- Science
for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, 17165 Solna, Sweden
| | - Erdinc Sezgin
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
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Drexhage LZ, Zhang S, Dupont M, Ragaller F, Sjule E, Cabezas-Caballero J, Deimel LP, Robertson H, Russell RA, Dushek O, Sezgin E, Karaji N, Sattentau QJ. Apoptosis-mediated ADAM10 activation removes a mucin barrier promoting T cell efferocytosis. Nat Commun 2024; 15:541. [PMID: 38225245 PMCID: PMC10789802 DOI: 10.1038/s41467-023-44619-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 12/22/2023] [Indexed: 01/17/2024] Open
Abstract
Efferocytic clearance of apoptotic cells in general, and T cells in particular, is required for tissue and immune homeostasis. Transmembrane mucins are extended glycoproteins highly expressed in the cell glycocalyx that function as a barrier to phagocytosis. Whether and how mucins may be regulated during cell death to facilitate efferocytic corpse clearance is not well understood. Here we show that normal and transformed human T cells express a subset of mucins which are rapidly and selectively removed from the cell surface during apoptosis. This process is mediated by the ADAM10 sheddase, the activity of which is associated with XKR8-catalyzed flipping of phosphatidylserine to the outer leaflet of the plasma membrane. Mucin clearance enhances uptake of apoptotic T cells by macrophages, confirming mucins as an enzymatically-modulatable barrier to efferocytosis. Together these findings demonstrate a glycocalyx regulatory pathway with implications for therapeutic intervention in the clearance of normal and transformed apoptotic T cells.
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Affiliation(s)
- Linnea Z Drexhage
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK
| | - Shengpan Zhang
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK
| | - Maeva Dupont
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK
- Immunocore Ltd., 92 Park Dr, Milton, Abingdon, OX14 4RY, UK
| | - Franziska Ragaller
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165, Solna, Sweden
| | - Ellen Sjule
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165, Solna, Sweden
| | | | - Lachlan P Deimel
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK
| | - Helen Robertson
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK
| | - Rebecca A Russell
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK
- SpyBiotech Ltd.; 7600 Quorum, Oxford Business Park North, Oxford, OX4 2JZ, UK
| | - Omer Dushek
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165, Solna, Sweden
| | - Niloofar Karaji
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK.
- Oxford Biomedica plc.; Windrush Court, Transport Way, Oxford, OX4 6LT, UK.
| | - Quentin J Sattentau
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford, OX13RE, UK.
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association; Berlin-Buch, 13125, Berlin, Germany.
- Experimental and Clinical Research Center (ECRC), Charité Universitätsmedizin Berlin and Max-Delbrück-Center for Molecular Medicine, Lindenberger Weg 80, 13125, Berlin, Germany.
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