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Dufourt J, Bellec M, Trullo A, Dejean M, De Rossi S, Favard C, Lagha M. Imaging translation dynamics in live embryos reveals spatial
heterogeneities. Science 2021; 372:840-844. [DOI: 10.1126/science.abc3483] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 04/13/2021] [Indexed: 12/21/2022]
Abstract
Much is known about the factors involved in the translation of messenger
RNA (mRNA) into protein; however, this multistep process has not been imaged
in living multicellular organisms. Here, we deploy the SunTag method to
visualize and quantify the timing, location, and kinetics of the translation
of single mRNAs in living Drosophila embryos. By
focusing on the translation of the conserved major epithelial-mesenchymal
transition–inducing transcription factor Twist, we identify spatial
heterogeneity in mRNA translation efficiency and reveal the existence of
translation factories, where clustered mRNAs are cotranslated preferentially
at basal perinuclear regions. Observing the location and dynamics of mRNA
translation in a living multicellular organism opens avenues for
understanding gene regulation during development.
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Affiliation(s)
- Jeremy Dufourt
- Institut de Génétique Moléculaire de Montpellier, University of
Montpellier, CNRS-UMR 5535, Montpellier 34293 cedex 5,
France
| | - Maelle Bellec
- Institut de Génétique Moléculaire de Montpellier, University of
Montpellier, CNRS-UMR 5535, Montpellier 34293 cedex 5,
France
| | - Antonio Trullo
- Institut de Génétique Moléculaire de Montpellier, University of
Montpellier, CNRS-UMR 5535, Montpellier 34293 cedex 5,
France
| | - Matthieu Dejean
- Institut de Génétique Moléculaire de Montpellier, University of
Montpellier, CNRS-UMR 5535, Montpellier 34293 cedex 5,
France
| | - Sylvain De Rossi
- MRI, BioCampus Montpellier, CNRS, INSERM, University of
Montpellier, Montpellier, France
| | - Cyril Favard
- Institut de Recherche en Infectiologie de Montpellier, CNRS UMR
9004, University of Montpellier, Montpellier 34293 cedex 5,
France
| | - Mounia Lagha
- Institut de Génétique Moléculaire de Montpellier, University of
Montpellier, CNRS-UMR 5535, Montpellier 34293 cedex 5,
France
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Abstract
The traditional methods to study lipid rafts and their association with membrane proteins are based mainly on the isolation of a detergent-resistant membrane by biochemical fractionation. However, the use of detergents may induce lipid segregation and/or redistribution of membrane proteins during the process of sample preparation. Here, we describe a detergent-free method to study the glycolipid and growth factor receptor interaction and their association with lipid rafts. This method combines the biochemical and immunoblotting tools with confocal microscopic imaging, which allows for evaluation and verification of the membrane protein interaction and association with the lipid rafts components in a multifaceted manner.
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Affiliation(s)
- Jing Wang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Robert K Yu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA.
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3
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Parslow AC, Clayton AHA, Lock P, Scott AM. Confocal Microscopy Reveals Cell Surface Receptor Aggregation Through Image Correlation Spectroscopy. J Vis Exp 2018:57164. [PMID: 30124657 PMCID: PMC6126602 DOI: 10.3791/57164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Confocal microscopy provides an accessible methodology to capture sub-cellular interactions critical for the characterization and further development of pre-clinical agents labeled with fluorescent probes. With recent advancements in antibody based cytotoxic drug delivery systems, understanding the alterations induced by these agents within the realm of receptor aggregation and internalization is of critical importance. This protocol leverages the well-established methodology of fluorescent immunocytochemistry and the open source FIJI distribution of ImageJ, with its inbuilt autocorrelation and image mathematical functions, to perform spatial image correlation spectroscopy (ICS). This protocol quantitates the fluorescent intensity of labeled receptors as a function of the beam area of the confocal microscope. This provides a quantitative measure of the state of target molecule aggregation on the cell surface. This methodology is focused on the characterization of static cells with potential to expand into temporal investigations of receptor aggregation. This protocol presents an accessible methodology to provide quantification of clustering events occurring at the cell surface, utilizing well established techniques and non-specialized imaging apparatus.
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Affiliation(s)
- Adam C Parslow
- Tumour Targeting Laboratory, Olivia Newton-John Cancer Research Institute; School of Cancer Medicine, La Trobe University
| | - Andrew H A Clayton
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology
| | - Peter Lock
- LIMS Bioimaging Facility, La Trobe Institute for Molecular Science, La Trobe University
| | - Andrew M Scott
- Tumour Targeting Laboratory, Olivia Newton-John Cancer Research Institute; School of Cancer Medicine, La Trobe University; Department of Medical Oncology, Olivia Newton-John Cancer and Wellnes Centre, Austin Health; Department of Medicine, University of Melbourne; Department of Molecular Imaging and Therapy, Austin Health;
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Lagerholm BC, Andrade DM, Clausen MP, Eggeling C. Convergence of lateral dynamic measurements in the plasma membrane of live cells from single particle tracking and STED-FCS. JOURNAL OF PHYSICS D: APPLIED PHYSICS 2017; 50:063001. [PMID: 28458397 PMCID: PMC5390782 DOI: 10.1088/1361-6463/aa519e] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 11/15/2016] [Accepted: 12/05/2016] [Indexed: 05/06/2023]
Abstract
Fluorescence correlation spectroscopy (FCS) in combination with the super-resolution imaging method STED (STED-FCS), and single-particle tracking (SPT) are able to directly probe the lateral dynamics of lipids and proteins in the plasma membrane of live cells at spatial scales much below the diffraction limit of conventional microscopy. However, a major disparity in interpretation of data from SPT and STED-FCS remains, namely the proposed existence of a very fast (unhindered) lateral diffusion coefficient, ⩾5 µm2 s-1, in the plasma membrane of live cells at very short length scales, ≈⩽ 100 nm, and time scales, ≈1-10 ms. This fast diffusion coefficient has been advocated in several high-speed SPT studies, for lipids and membrane proteins alike, but the equivalent has not been detected in STED-FCS measurements. Resolving this ambiguity is important because the assessment of membrane dynamics currently relies heavily on SPT for the determination of heterogeneous diffusion. A possible systematic error in this approach would thus have vast implications in this field. To address this, we have re-visited the analysis procedure for SPT data with an emphasis on the measurement errors and the effect that these errors have on the measurement outputs. We subsequently demonstrate that STED-FCS and SPT data, following careful consideration of the experimental errors of the SPT data, converge to a common interpretation which for the case of a diffusing phospholipid analogue in the plasma membrane of live mouse embryo fibroblasts results in an unhindered, intra-compartment, diffusion coefficient of ≈0.7-1.0 µm2 s-1, and a compartment size of about 100-150 nm.
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Affiliation(s)
- B Christoffer Lagerholm
- Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK
| | - Débora M Andrade
- Centre for Neural Circuits and Behaviour, University of Oxford, Mansfield Road, Oxford OX1 3SR, UK
| | - Mathias P Clausen
- MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, Odense M DK-5230, Denmark
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK
| | - Christian Eggeling
- Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK
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Godin AG, Rappaz B, Potvin-Trottier L, Kennedy TE, De Koninck Y, Wiseman PW. Spatial Intensity Distribution Analysis Reveals Abnormal Oligomerization of Proteins in Single Cells. Biophys J 2016; 109:710-21. [PMID: 26287623 DOI: 10.1016/j.bpj.2015.06.068] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/09/2015] [Accepted: 06/22/2015] [Indexed: 12/30/2022] Open
Abstract
Knowledge of membrane receptor organization is essential for understanding the initial steps in cell signaling and trafficking mechanisms, but quantitative analysis of receptor interactions at the single-cell level and in different cellular compartments has remained highly challenging. To achieve this, we apply a quantitative image analysis technique-spatial intensity distribution analysis (SpIDA)-that can measure fluorescent particle concentrations and oligomerization states within different subcellular compartments in live cells. An important technical challenge faced by fluorescence microscopy-based measurement of oligomerization is the fidelity of receptor labeling. In practice, imperfect labeling biases the distribution of oligomeric states measured within an aggregated system. We extend SpIDA to enable analysis of high-order oligomers from fluorescence microscopy images, by including a probability weighted correction algorithm for nonemitting labels. We demonstrated that this fraction of nonemitting probes could be estimated in single cells using SpIDA measurements on model systems with known oligomerization state. Previously, this artifact was measured using single-step photobleaching. This approach was validated using computer-simulated data and the imperfect labeling was quantified in cells with ion channels of known oligomer subunit count. It was then applied to quantify the oligomerization states in different cell compartments of the proteolipid protein (PLP) expressed in COS-7 cells. Expression of a mutant PLP linked to impaired trafficking resulted in the detection of PLP tetramers that persist in the endoplasmic reticulum, while no difference was measured at the membrane between the distributions of wild-type and mutated PLPs. Our results demonstrate that SpIDA allows measurement of protein oligomerization in different compartments of intact cells, even when fractional mislabeling occurs as well as photobleaching during the imaging process, and reveals insights into the mechanism underlying impaired trafficking of PLP.
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Affiliation(s)
- Antoine G Godin
- Department of Physics, McGill University, Montréal, Québec, Canada; Institut Universitaire en Santé Mentale de Québec, Québec, Canada
| | - Benjamin Rappaz
- Department of Physics, McGill University, Montréal, Québec, Canada; Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada; Program in NeuroEngineering, McGill University, Montréal, Québec, Canada
| | | | - Timothy E Kennedy
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada; Program in NeuroEngineering, McGill University, Montréal, Québec, Canada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de Québec, Québec, Canada; Département de Psychiatrie et Neurosciences, Université Laval, Québec, Canada; Department of Pharmacology & Therapeutics, McGill University, Montréal, Québec, Canada; Alan Edwards Center for Research of Pain, McGill University, Montréal, Québec, Canada
| | - Paul W Wiseman
- Department of Physics, McGill University, Montréal, Québec, Canada; Program in NeuroEngineering, McGill University, Montréal, Québec, Canada; Department of Chemistry, McGill University, Montréal, Québec, Canada.
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Adler J, Parmryd I. Quantifying colocalization: thresholding, void voxels and the H(coef). PLoS One 2014; 9:e111983. [PMID: 25375829 PMCID: PMC4222960 DOI: 10.1371/journal.pone.0111983] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/08/2014] [Indexed: 11/18/2022] Open
Abstract
A critical step in the analysis of images is identifying the area of interest e.g. nuclei. When the nuclei are brighter than the remainder of the image an intensity can be chosen to identify the nuclei. Intensity thresholding is complicated by variations in the intensity of individual nuclei and their intensity relative to their surroundings. To compensate thresholds can be based on local rather than global intensities. By testing local thresholding methods we found that the local mean performed poorly while the Phansalkar method and a new method based on identifying the local background were superior. A new colocalization coefficient, the H(coef), highlights a number of controversial issues. (i) Are molecular interactions measurable (ii) whether to include voxels without fluorophores in calculations, and (iii) the meaning of negative correlations. Negative correlations can arise biologically (a) because the two fluorophores are in different places or (b) when high intensities of one fluorophore coincide with low intensities of a second. The cases are distinct and we argue that it is only relevant to measure correlation using pixels that contain both fluorophores and, when the fluorophores are in different places, to just report the lack of co-occurrence and omit these uninformative negative correlation. The H(coef) could report molecular interactions in a homogenous medium. But biology is not homogenous and distributions also reflect physico-chemical properties, targeted delivery and retention. The H(coef) actually measures a mix of correlation and co-occurrence, which makes its interpretation problematic and in the absence of a convincing demonstration we advise caution, favouring separate measurements of correlation and of co-occurrence.
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Affiliation(s)
- Jeremy Adler
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Ingela Parmryd
- Department of Medical Cell Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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