Coiled-Coil-Templated Acyl Transfer Reactions on the Surface of Living Cells

Fluoreszenzmarkierungstechniken für lebende Zellen ermöglichen es Biologen, einen Blick in eine komplexe biologische Umgebung zu werfen und Informationen über ein bestimmtes Ziel in einer nahezu natürlichen Umgebung zu erhalten. Dank der konzertierten Bemühungen der wissenschaftlichen Gemeinschaft gibt es eine Fülle von kommerziell erhältlichen, genetisch kodierbaren Markern und Reportern für die Fluoreszenzmikroskopie. Allerdings gibt es nur wenige Lebendzellmethoden, die eine direkte Konjugation von Nukleinsäuren mit Proteinen erlauben, obwohl es robuste DNA-Technologien gibt, die mit Oligo-Antikörper-Konjugaten auf Zelloberflächen durchgeführt werden. Ein weiterer, oft einschränkender Aspekt der Markierung ist die Fähigkeit, Ziele selektiv zu multiplexen. In dieser Studie wurde eine Methode der Tag-Probe-Markierung entwickelt, die eine selektive, gleichzeitige Markierung von zwei verschiedenen Zielen mit zwei Peptid-Nukleinsäure-Strängen (PNA) ermöglicht. Diese Methode verwendet ein Paar von Coiled-Coil-Peptiden, um die Konjugation einer PNA-Gruppe an ein Zielprotein zu steuern, das ein Peptid-Tag exprimiert. Die Verwendung orthogonaler Coiled-Coils ermöglicht Multiplexing. Die Markierung von synthetischen Tag-Peptiden, die mittels Flüssigchromatographie analysiert wurden, hat gezeigt, dass der orthogonale duale Transfer von PNA selektiv, quantitativ und schnell ist. Die PNA-Konjugation von exemplarischen Membranrezeptoren, gefolgt von der Hybridisierung mit komplementären Fluorophor-DNAs, ermöglichte eine unkomplizierte Visualisierung von dualen Rezeptoren in lebenden Zellen. Durch den Einsatz einfacher molekularer Hilfsmittel, die die Grundlage der DNA-Nanotechnologie bilden, konnte durch die Rekrutierung mehrerer DNAs eine zunehmend hellere Markierung erreicht werden und die löschbare Oberflächenmarkierung ermöglichte eine quantitative Untersuchung der Rezeptorinternalisierung.Live-cell fluorescent labelling techniques allow biologists to glimpse into a complex biological environment and derive information about a specific target in a near-native environment. Thanks to a concerted effort from the scientific community, a plethora of commercially available, genetically encodable tags and reporters for fluorescence microscopy exist. However, few live-cell methods allow direct conjugation of nucleic acids with proteins despite the robust DNA technologies carried out on cell surfaces using oligo-antibody conjugates. Another aspect of labelling which is often limiting is the ability to selectively multiplex targets. In this study, a method of tag–probe labelling was developed that accomplishes selective, simultaneous labelling of two distinct targets with two peptide nucleic acid (PNA) strands. The technique uses a pair of coiled-coil peptides to guide conjugation of a PNA group to a target protein expressing a peptide tag and using orthogonal coiled-coil enables multiplexing. Initially, the labelling of synthetic tag-peptides analysed by liquid chromatography revealed the orthogonal dual transfer of PNA to be selective, quantitative, and rapid. PNA conjugation of exemplar membrane receptors followed by hybridization with complementary fluorophore-DNAs achieved straightforward live-cell dual receptor visualization. Finally, using simple molecular tools that form the basis of DNA nanotechnology, recruitment of multiple DNAs facilitated progressively brighter labelling, and erasable surface labelling allowed quantitative study of receptor internalisation

Are formyl peptide receptors novel targets for therapeutic intervention in ischaemia-reperfusion injury?

Ischaemia–reperfusion (I/R) injury is a common feature of several diseases associated with high morbidity and mortality, such as stroke and myocardial infarction. The damaged tissue displays cardinal signs of inflammation and microvascular injury that, unless resolved, lead to long-term tissue damage with associated dysfunction. Current therapies are limited and are often associated with many side effects. Increasing evidence suggests that members of the formyl peptide receptor (FPR) family, in particular human FPR2/ALX, might have an important role in the pathophysiology of I/R injury. It was recently demonstrated that several peptides and non-peptidyl small-molecule compounds have anti-inflammatory and pro-resolving properties via their action on members of the FPR family. Here I review this evidence and suggest that FPR ligands, particularly in the brain, could be novel and exciting anti-inflammatory therapeutics for the treatment of a variety of clinical conditions, including stroke

The Resolution Mediator Annexin A1 Affords Protection Against Thromboinflammation

Meeting poster 331.Thrombosis presented at the 63rd ASH Annual Meeting and Exposition, Atlanta, GA, USA, 11-14 December, 2021.Stroke is a leading cause of death and disability worldwide, with the majority (~85 %) being ischemic in origin. Age is the most important non-modifiable risk factor for acute ischemic stroke (AIS). While inflammation with ageing is a well-known complication of AIS, a new model is emerging in which ageing-associated thrombosis is being viewed as a multi-step, multi-cellular process driven by inflammatory stimuli and recruitment/activation of leukocytes. The ideal outcome of inflammation is resolution, an active process involving specific endogenous mediators (e.g. annexin A1 [AnxA1]) and related pathways (e.g. formyl peptide receptor-2 [Fpr2/ALX] pathway).[1,2] The development of therapies that temper inflammation and enhance resolution offer potential therapeutic strategies for the treatment and management of thromboinflammation associated with AIS. We have shown that the AnxA1 mimetic peptide AnxA1 Ac2-26 ameliorates thrombotic responses in thromboinflammatory conditions such as Sickle Cell Disease,[3] however, the role that AnxA1 plays in age-related thrombosis is currently unknown. Here we sought to comprehensively elucidate the functional significance of targeting the AnxA1/Fpr2/ALX pathway in age-related thrombosis. Initially, to evaluate the role of AnxA1, thrombosis in cerebral vessels was induced using the light/dye thrombosis model.[2] Male and female adult (10-14 weeks) and ageing (18-24 months) wild type (WT, C57/BL6) or AnxA1 knock-out (AnxA1 -/-) mice were used. WT mice received AnxA1 (1 µg/mouse), or saline vehicle injected 20 min before the onset of thrombus formation in cerebral pial vessels. Thrombogenesis and blood flow cessation times were quantified. AnxA1 treatment was able to prolong blood flow cessation times in both cerebral arterioles and venules, an effect which was more pronounced in ageing mice (p<0.05) via regulation of the FPR2/ALX-pathway. Next, to investigate the mechanism of action of AnxA1 in an inflammatory backdrop (i.e. lipopolysaccharide [LPS]), the effect of AnxA1 on platelet P‐selectin and αIIbβ3 receptor expression, following stimulation with the GPVI collagen receptor agonist convulxin (CVX), was performed. CVX treatment increased platelet activation, which was suppressed by AnxA1 co‐administration (100 ng. p<0.05). CVX+LPS increased platelet αIIbβ3 or P‐selectin levels, which were inhibited by the administration of AnxA1. Finally, to determine whether a deletion of AnxA1 impacts thrombosis, we performed the light/dye thrombosis model in AnxA1 −/− mice. These mice displayed accelerated cerebral microvascular thrombus formation (decrease in blood flow cessation time) compared to WT mice in both arterioles and venules (arterioles: 17.9 ± 2.3 vs 33.2 ± 1.9 min and venules: 13.2 ± 2.4 vs 20.9 ± 2.2 min. p<0.05). In conclusion, these results demonstrate the ability of AnxA1 to modify the thromboinflammatory environment, including reducing platelet activation under inflammatory conditions via GPVI. Collectively, these data show the importance of the AnxA1/Fpr2/ALX system in effecting the resolution of cerebral thromboinflammation in ageing and may provide a novel therapeutic strategy for AIS and other thromboinflammatory conditions. Disclosures No relevant conflicts of interest to declare.Royal Society Wolfson Fellowship ref: RSWF\R3\183001

Strategies for Site‐Specific Labeling of Receptor Proteins on the Surfaces of Living Cells by Using Genetically Encoded Peptide Tags

Fluorescence microscopy imaging enables receptor proteins to be investigated within their biological context. A key challenge is to site-specifically incorporate reporter moieties into proteins without interfering with biological functions or cellular networks. Small peptide tags offer the opportunity to combine inducible labeling with small tag sizes that avoid receptor perturbation. Herein, we review the current state of live-cell labeling of peptide-tagged cell-surface proteins. Considering their importance as targets in medicinal chemistry, we focus on membrane receptors such as G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). We discuss peptide tags that i) are subject to enzyme-mediated modification reactions, ii) guide the complementation of reporter proteins, iii) form coiled-coil complexes, and iv) interact with metal complexes. Given our own contributions in the field, we place emphasis on peptide-templated labeling chemistry.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Leipzig School of Natural SciencesPeer Reviewe

IEP development as a function of pedagogical experience in special education teachers

The overarching goal of this study was to examine performance during development of the individualized educational plan (IEP) for students with disabilities as a function of pedagogical experience among special education teachers. Qualitative methods were used to describe how special education teachers, categorized as more experienced and less experienced, differed in developing goals and objectives and how their differences aligned with the stages of expertise development proposed in the Model of Domain Learning. Specifically, three more and three less experienced special education teachers who serviced students with disabilities in resource room settings, participated in a one-hour verbal protocol procedure while engaging in the explicit task of developing an IEP for a simulated student profile. Data sources included questionnaires, direct observations and recordings of participant verbalizations during the task of IEP development, follow up interviews, and permanent products. Data codes were based on the preliminary findings from a pilot study and heavily informed by existing literature related to expertise development, pedagogical knowledge of special educators, and IEP development. Findings highlighted specific differences in the demonstrated knowledge and strategic processing of the participants across experience levels. The demonstrated foundational knowledge and use of surface level strategic processing by the less experienced special education teachers was consistent with learner behaviors described in the acclimation stage of development in the Model of Domain Learning. The more experienced participants exhibited early, middle, and late characterizations consistent with the competency stage of development. There were marked similarities between the written IEP goal and objectives between the less experienced participants and two of the more experienced participants. Several issues emerged as possible factors for these similarities: a) training on goal development, b) problematic implementation of IEP development strategies, and c) participant perceptions of the significance of the IEP goals and objectives. Specifically, the following conclusions were drawn: a) developing IEP goals and objectives that are instructionally relevant and technically adequate continues to be problematic, b) there is not a consistent direct relationship between years of experience and the procedural integrity of the developed IEP goals and objectives, and c) interventions based on models of development that offer a well conceptualized understanding of how domain expertise emerges and provides a full description of expected behaviors across a trajectory of development would be beneficial to both preservice and inservice special education teachers

⁹⁹ᵐTc SPECT imaging agent based on cFLFLFK for the detection of FPR1 in inflammation

Non-invasive imaging of the inflammatory process can provide a great deal of insight into a wide variety of diseases states, aiding diagnosis, evaluation and effective targeted treatment. During inflammation, blood borne leukocytes are recruited, through a series of activation and adhesion steps, to the site of injury or infection where they migrate across the blood vessel wall into the tissue. Thus, tracking leukocyte recruitment and accumulation provides a dynamic and localised read out of inflammatory events. Current leukocyte imaging techniques require ex vivo labelling of patient blood, involving laborious processing and potential risks to both patient and laboratory staff. Utilising high affinity ligands for leukocyte specific receptors may allow for injectable tracers that label leukocytes in situ, omitting potentially hazardous ex vivo handling. Formyl peptide receptors (FPRs) are a group of G-protein coupled receptors involved in the chemotaxis and inflammatory functioning of leukocytes. Highly expressed on leukocytes, and up regulated during inflammation, these receptors provide a potential target for imaging inflammatory events. Herein we present the synthesis and initial in vitro testing of a potential Single Photon Emission Computed Tomography (SPECT) leukocyte tracer. The FPR1 antagonist cFLFLFK-NH₂, which displays high affinity with little physiological effect, has been linked via a PEG motif to a ⁹⁹ᵐTc chelate. This tracer shows in vitro binding to human embryonic kidney cells expressing the FPR1 receptor, and functional in vitro tests reveal cFLFLFK-NH₂ compounds to have no effect on inflammatory cell functioning. Overall, these data show that ⁹⁹ᵐTc.cFLFLFK-NH₂ may be a useful tool for non-invasive imaging of leukocyte accumulation in inflammatory disease states

The Impact of Thrombo‐inflammation on the Cerebral Microcirculation

Copyright © 2021 The Authors. The intertwined processes of thrombosis and inflammation (termed “thrombo-inflammation”) are significant drivers of cerebrovascular diseases, and as such, they represent prime targets for drug discovery programs focusing on treatment and management of cerebrovascular diseases. Most cerebrovascular events result from chronic systemic microcirculatory dysfunction due to underlying conditions, for example, hypertension, diabetes mellitus, coronary artery disease, dyslipidemia, and sickle cell disease. Immune cells especially neutrophils play a critical role in the onset and maintenance of neuroinflammatory responses in the microcirculation. Neutrophils have the ability to drive both inflammatory and anti-inflammatory/pro-resolution effects depending on the underlying vascular state (physiological vs. pathological). In this article, we highlight the pathophysiological role of neutrophils in stroke and discuss ongoing pharmacotherapeutic strategies that are focused on identifying potential therapeutic targets for enhancing neuroprotection, mitigating inflammatory pathways, and enabling resolution.The Royal Society Wolfson Foundation. Grant Number: RSWF\R3\18300

Text world theory : A critical exposition and development in relation to absurd prose fiction.

This thesis presents a unified and systematic Text World Theory, tested and refined under practical application. It draws on a variety of linguistic, psychological, critical theoretical and cognitive scientific models, principally the cognitive discourse grammar originally developed by Paul Werth. The thesis delineates the critical and philosophical inheritance out of which Text World Theory evolved, in order to evaluate and engage critically with the theoretical framework in the light of recent developments in literary linguistics and cognitive poetics. This inheritance includes the fields of possible worlds semantics and narratology, artificial intelligence research and cognitive psychology. Essential modifications, revisions and crucial adjustments are made to Werth's approach in order to produce a refined model of Text World Theory. The augmented framework is tested through several practical and inter-related analyses. These centre around Absurd prose fiction, selected in order to highlight the adaptability of the new Text World Theory especially in the context of literary environments that are often judged to be challenging on a cognitive dimension. Extensive analyses of Paul Auster's The Music of Chance, Flann O'Brien's The Third Policeman, Emmanuel Carrere's The Mustache, Kurt Vonnegut's Slaughterhouse-Five, and Donald Barthelme's Snow White are undertaken over the course of the thesis. Further adaptations to the model are proposed as a result of these applications. The thesis aims primarily to be a contribution to the field of cognitive discourse study. However, incidental contributions are also made to the areas of the critical study of Absurd prose fiction, pragmatics and semantics, cognitive poetics and literary critical theory in general

Thromboinflammation in coronavirus disease 2019: The clot thickens

Copyright © 2021 The Authors. Since the start of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, a disease that has become one of the world's greatest global health challenges, the role of the immune system has been at the forefront of scientific studies. The pathophysiology of coronavirus disease 2019 (COVID-19) is complex, which is evident in those at higher risk for poor outcome. Multiple systems contribute to thrombosis and inflammation seen in COVID-19 patients, including neutrophil and platelet activation, and endothelial dysfunction. Understanding how the immune system functions in different patient cohorts (particularly given recent emerging events with the Oxford/AstraZeneca vaccine) is vital to understanding the pathophysiology of this devastating disease and for the subsequent development of novel therapeutic targets and to facilitate possible drug repurposing strategies that could benefit society on a global scale.Royal Society Wolfson Foundation. Grant Number: RSWF\R3\18300