ORCID Profile
0000-0001-5847-5226
Current Organisation
University of Oxford
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Publisher: Springer Science and Business Media LLC
Date: 20-08-2020
DOI: 10.1038/S41467-020-17970-3
Abstract: T cells engineered to express chimeric antigen receptors (CAR-T cells) have shown impressive clinical efficacy in the treatment of B cell malignancies. However, the development of CAR-T cell therapies for solid tumors is h ered by the lack of truly tumor-specific antigens and poor control over T cell activity. Here we present an avidity-controlled CAR (AvidCAR) platform with inducible and logic control functions. The key is the combination of (i) an improved CAR design which enables controlled CAR dimerization and (ii) a significant reduction of antigen-binding affinities to introduce dependence on bivalent interaction, i.e. avidity. The potential and versatility of the AvidCAR platform is exemplified by designing ON-switch CARs, which can be regulated with a clinically applied drug, and AND-gate CARs specifically recognizing combinations of two antigens. Thus, we expect that AvidCARs will be a highly valuable platform for the development of controllable CAR therapies with improved tumor specificity.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-03-2017
Abstract: Tethering of the cytoplasmic tyrosine phosphatase SHP-1 to clustered receptors increases its activity 900-fold.
Publisher: Cold Spring Harbor Laboratory
Date: 05-09-2020
DOI: 10.1101/2020.09.04.283341
Abstract: Immune receptor signalling proceeds by the binding (or tethering) of enzymes to their cytoplasmic tails before they catalyse reactions on substrates within reach. This is the case for the enzyme SHP-1 that, upon tethering to the inhibitory receptor PD-1, dephosphorylates membrane substrates to suppress T cell activation. Precisely how tethering regulates SHP-1 activity is incompletely understood. Here, we use surface plasmon resonance to measure binding, catalysis, and molecular reach for PD-1 tethered SHP-1 reactions. We find that the reach of PD-1—SHP-1 complexes is dominated by the 13.0 nm reach of SHP-1 itself. This is longer than an estimate from the structure of the allosterically active conformation (5.3 nm), suggesting that SHP-1 explores multiple active conformations. Using modelling, we show that when uniformly distributed, PD-1—SHP-1 complexes can only reach 15% of substrates but this increases to 90% when they are co-clustered. When within reach, we show that membrane recruitment increases the activity of SHP-1 by a 1000-fold increase in local concentration. The work highlights how molecular reach regulates the activity of membrane-recruited SHP-1 with insights applicable to other membrane-tethered reactions. Immune receptors transduce signals by recruiting (or tethering) cytoplasmic enzymes to their tails at the membrane. When tethered, these enzymes catalyse reactions on other substrates to propagate signalling. Precisely how membrane tethering regulates enzyme activity is incompletely understood. Unlike other tethered reactions, where the enzyme tethers to the substrate, the substrate in this case is a different receptor tail. Therefore, the ability of the receptor-tethered enzyme to reach a substrate can be critical in controlling reaction rates. In this work, we determine the molecular reach for the enzyme SHP-1 and the receptor PD-1 to which it can tether, and show how molecular reach controls receptor signalling.
Publisher: EMBO
Date: 08-12-2016
Publisher: Elsevier BV
Date: 10-2019
Publisher: Elsevier BV
Date: 05-2021
Publisher: Cold Spring Harbor Laboratory
Date: 23-08-2023
DOI: 10.1101/2023.08.22.554267
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 act as a barrier to phagocytosis. Whether and how mucins may be regulated during cell death to facilitate efferocytic corpse clearance is not 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 reveal a novel glycocalyx regulatory pathway with implications for therapeutic intervention in the clearance of normal and transformed apoptotic T cells.
Publisher: Proceedings of the National Academy of Sciences
Date: 23-02-2022
Abstract: Src homology 2 (SH2) domains are phosphotyrosine binding motifs that play key roles in cellular signaling. There are 110 proteins in the human genome containing SH2 binding domains, of which 10 contain tandem SH2 domains. Tandem domains have been shown to improve avidity and specificity and contribute to allostery. Here, we show that tandem SH2 domains can also exhibit binding lifetimes that are accelerated by the activity of phosphatases. This accelerated unbinding requires tandem SH2 domains to engage their substrates in dynamic binding modes that cycle between single SH2-bound states. We experimentally confirm that this is the case for the well-studied kinase ZAP70 binding the T cell receptor. We suggest that accelerated unbinding is a general feature of signaling networks.
Publisher: Proceedings of the National Academy of Sciences
Date: 20-06-2019
Abstract: One approach to testing biological theories is to determine if they are predictive. We have developed a simple, theoretical treatment of T cell receptor (TCR) triggering that relies on just two physical principles: ( i ) the time TCRs spend in cell–cell contacts depleted of large tyrosine phosphatases and ( ii ) constraints on the size of these contacts imposed by cell topography. The theory not only distinguishes between agonistic and nonagonistic TCR ligands but predicts the relative signaling potencies of agonists with remarkable accuracy. These findings suggest that the theory captures the essential features of receptor triggering.
Publisher: Cold Spring Harbor Laboratory
Date: 13-02-2020
DOI: 10.1101/2020.02.12.945170
Abstract: Protein-protein binding domains are critical in signalling networks. Src homology 2 (SH2) domains are binding domains that interact with sequences containing phosphorylated tyrosines. A subset of SH2 domain-containing proteins have tandem domains, which are thought to enhance binding affinity and specificity. However, a trade-off exists between long-lived binding and the ability to rapidly reverse signalling, which is a critical requirement of noise filtering mechanisms such as kinetic proofreading. Here, we use modelling to show that the unbinding rate of tandem, but not single, SH2 domains can be accelerated by phosphatases when tandem domains bind by a kinetic, but not a static, avidity mode. We use surface plasmon resonance to show that ZAP70, a tandem SH2 domain-containing kinase, binds kinetically to biphosphorylated peptides from the T cell antigen receptor (TCR) and that the unbinding rate can be accelerated by the phosphatase CD45. An important functional prediction of regulated unbinding is that the intracellular ZAP70/TCR half-life in T cells will be correlated to the extracellular TCR/antigen half-life and we show that this is the case in both cell lines and primary T cells. The work highlights that binding by kinetic avidity breaks the trade-off between signal fidelity (requiring long half-life) and signal reversibility (requiring short half-life), which is a key requirement for T cell antigen discriminated mediated by kinetic proofreading.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Omer Dushek.