TCR and Lat are expressed on separate protein islands on T cell membranes and concatenate during activation
TL;DR: The spatio-temporal dynamics of T cell antigen receptor (TCR) complexes and linker for activation of T cells (Lat), a key adaptor molecule in the TCR signaling pathway, are analyzed in T cell membranes using high-speed photoactivated localization microscopy, dual-color fluorescence cross-correlation spectroscopy and transmission electron microscopy.
Abstract: TCR movement in the T cell plasma membrane is not well understood. Using three different types of microscopy, Davis and co-workers identify separate islands of Lat and TCR molecules that concatenate after T cell activation.
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TL;DR: How the field has matured and an evolving model in which membranes are occupied by fluctuating nanoscale assemblies of sphingolipids, cholesterol and proteins that can be stabilized into platforms that are important in signalling, viral infection and membrane trafficking are presented.
Abstract: Ten years ago, we wrote a Review on lipid rafts and signalling in the launch issue of Nature Reviews Molecular Cell Biology. At the time, this field was suffering from ambiguous methodology and imprecise nomenclature. Now, new techniques are deepening our insight into the dynamics of membrane organization. Here, we discuss how the field has matured and present an evolving model in which membranes are occupied by fluctuating nanoscale assemblies of sphingolipids, cholesterol and proteins that can be stabilized into platforms that are important in signalling, viral infection and membrane trafficking.
1,151 citations
Cites methods from "TCR and Lat are expressed on separa..."
...but high-resolution microscopy methods show complexes with up to 7–20 TCRs, which are manifested as protein islands that are 70–140 nm in diamete...
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TL;DR: It is demonstrated that protein phase separation can create a distinct physical and biochemical compartment that facilitates signaling and promote signaling outputs both in vitro and in human Jurkat T cells.
Abstract: Activation of various cell surface receptors triggers the reorganization of downstream signaling molecules into micrometer- or submicrometer-sized clusters. However, the functional consequences of such clustering have been unclear. We biochemically reconstituted a 12-component signaling pathway on model membranes, beginning with T cell receptor (TCR) activation and ending with actin assembly. When TCR phosphorylation was triggered, downstream signaling proteins spontaneously separated into liquid-like clusters that promoted signaling outputs both in vitro and in human Jurkat T cells. Reconstituted clusters were enriched in kinases but excluded phosphatases and enhanced actin filament assembly by recruiting and organizing actin regulators. These results demonstrate that protein phase separation can create a distinct physical and biochemical compartment that facilitates signaling.
853 citations
TL;DR: A new mechanism by which the antitumour response of mouse CD8+ T cells can be potentiated by modulating cholesterol metabolism is reported, which indicates ACAT1, an established target for atherosclerosis, is therefore also a potential target for cancer immunotherapy.
Abstract: CD8(+) T cells have a central role in antitumour immunity, but their activity is suppressed in the tumour microenvironment. Reactivating the cytotoxicity of CD8(+) T cells is of great clinical interest in cancer immunotherapy. Here we report a new mechanism by which the antitumour response of mouse CD8(+) T cells can be potentiated by modulating cholesterol metabolism. Inhibiting cholesterol esterification in T cells by genetic ablation or pharmacological inhibition of ACAT1, a key cholesterol esterification enzyme, led to potentiated effector function and enhanced proliferation of CD8(+) but not CD4(+) T cells. This is due to the increase in the plasma membrane cholesterol level of CD8(+) T cells, which causes enhanced T-cell receptor clustering and signalling as well as more efficient formation of the immunological synapse. ACAT1-deficient CD8(+) T cells were better than wild-type CD8(+) T cells at controlling melanoma growth and metastasis in mice. We used the ACAT inhibitor avasimibe, which was previously tested in clinical trials for treating atherosclerosis and showed a good human safety profile, to treat melanoma in mice and observed a good antitumour effect. A combined therapy of avasimibe plus an anti-PD-1 antibody showed better efficacy than monotherapies in controlling tumour progression. ACAT1, an established target for atherosclerosis, is therefore also a potential target for cancer immunotherapy.
580 citations
554 citations
TL;DR: PC-PALM is an effective tool with broad applicability for analysis of protein heterogeneity and function, adaptable to other single-molecule strategies, and shows dramatic changes in glycosylphosphatidylinositol (GPI)-anchored protein arrangement under varying perturbations.
Abstract: Photoactivated localization microscopy (PALM) is a powerful approach for investigating protein organization, yet tools for quantitative, spatial analysis of PALM datasets are largely missing. Combining pair-correlation analysis with PALM (PC-PALM), we provide a method to analyze complex patterns of protein organization across the plasma membrane without determination of absolute protein numbers. The approach uses an algorithm to distinguish a single protein with multiple appearances from clusters of proteins. This enables quantification of different parameters of spatial organization, including the presence of protein clusters, their size, density and abundance in the plasma membrane. Using this method, we demonstrate distinct nanoscale organization of plasma-membrane proteins with different membrane anchoring and lipid partitioning characteristics in COS-7 cells, and show dramatic changes in glycosylphosphatidylinositol (GPI)-anchored protein arrangement under varying perturbations. PC-PALM is thus an effective tool with broad applicability for analysis of protein heterogeneity and function, adaptable to other single-molecule strategies.
552 citations
References
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TL;DR: This work introduced a method for optically imaging intracellular proteins at nanometer spatial resolution and used this method to image specific target proteins in thin sections of lysosomes and mitochondria and in fixed whole cells to image retroviral protein Gag at the plasma membrane.
Abstract: We introduce a method for optically imaging intracellular proteins at nanometer spatial resolution. Numerous sparse subsets of photoactivatable fluorescent protein molecules were activated, localized (to approximately 2 to 25 nanometers), and then bleached. The aggregate position information from all subsets was then assembled into a superresolution image. We used this method--termed photoactivated localization microscopy--to image specific target proteins in thin sections of lysosomes and mitochondria; in fixed whole cells, we imaged vinculin at focal adhesions, actin within a lamellipodium, and the distribution of the retroviral protein Gag at the plasma membrane.
7,924 citations
"TCR and Lat are expressed on separa..." refers methods in this paper
...We achieved this with a combination of three techniques: a modified high-speed version of photoactivated localization microscopy (hsPALM...
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TL;DR: A high-resolution fluorescence microscopy method based on high-accuracy localization of photoswitchable fluorophores that can, in principle, reach molecular-scale resolution is developed.
Abstract: We have developed a high-resolution fluorescence microscopy method based on high-accuracy localization of photoswitchable fluorophores. In each imaging cycle, only a fraction of the fluorophores were turned on, allowing their positions to be determined with nanometer accuracy. The fluorophore positions obtained from a series of imaging cycles were used to reconstruct the overall image. We demonstrated an imaging resolution of 20 nm. This technique can, in principle, reach molecular-scale resolution.
7,213 citations
TL;DR: Immunological synapse formation is now shown to be an active and dynamic mechanism that allows T cells to distinguish potential antigenic ligands and was a determinative event for T cell proliferation.
Abstract: The specialized junction between a T lymphocyte and an antigen-presenting cell, the immunological synapse, consists of a central cluster of T cell receptors surrounded by a ring of adhesion molecules. Immunological synapse formation is now shown to be an active and dynamic mechanism that allows T cells to distinguish potential antigenic ligands. Initially, T cell receptor ligands were engaged in an outermost ring of the nascent synapse. Transport of these complexes into the central cluster was dependent on T cell receptor—ligand interaction kinetics. Finally, formation of a stable central cluster at the heart of the synapse was a determinative event for T cell proliferation. A critical event in the initiation of the adaptive
2,988 citations
TL;DR: In this article, a method for producing high-titer, helper-free infectious retroviruses is disclosed which employs a novel strategy that uses transient transfection of new retroviral producer cell lines, ecotropic line BOSC 23 and amphotropic line CAK 8.
Abstract: A method for producing high-titer, helper-free infectious retroviruses is disclosed which employs a novel strategy that uses transient transfection of new retroviral producer cell lines, ecotropic line BOSC 23 and amphotropic line CAK 8, both of which cell lines and their precursor cell lines are disclosed. Because of the advantages over stable packaging cell lines, the BOSC 23 and CAK 8 transient transfection systems greatly facilitate and extend the use of helper-free retroviral vectors. The cell lines and corresponding methods possess wide application in both the medical and biotechnical fields, including gene therapy. These potential applications are disclosed and illustrated.
2,587 citations
TL;DR: The three-dimensional distribution of receptors and intracellular proteins that cluster at the contacts between T cells and APCs during antigen-specific interactions, Surprisingly, instead of showing uniform oligomerization, these proteins clustered into segregated three- dimensional domains within the cell contacts.
Abstract: Activation of T cells by antigen-presenting cells (APCs) depends on the complex integration of signals that are delivered by multiple antigen receptors. Most receptor-proximal activation events in T cells were identified using multivalent anti-receptor antibodies, eliminating the need to use the more complex APCs. As the physiological membrane-associated ligands on the APC and the activating antibodies probably trigger the same biochemical pathways, it is unknown why the antibodies, even at saturating concentrations, fail to trigger some of the physiological T-cell responses. Here we study, at the level of the single cell, the responses of T cells to native ligands. We used a digital imaging system and analysed the three-dimensional distribution of receptors and intracellular proteins that cluster at the contacts between T cells and APCs during antigen-specific interactions. Surprisingly, instead of showing uniform oligomerization, these proteins clustered into segregated three-dimensional domains within the cell contacts. The antigen-specific formation of these new, spatially segregated supramolecular activation clusters may generate appropriate physiological responses and may explain the high sensitivity of the T cells to antigen.
2,355 citations