Biology subjects

Weil, T.

Publications and source records attributed to Weil, T..

8 recordsLinked to original sources

bioRxiv2024

Non-invasive visualization of pH changes within the tumor-micro-environment by positron emission tomography

Slight changes in the pH value of the tumor microenvironment (TME) have crucial effects on host defense, metastatic behavior, immune regulation and cellular metabolism. Due to the high metabolic activity and insufficient perfusion of tumors, acidic metabolites often accumulate in tumors and can influence the pH of the TME. Several studies have shown that the acidity of the interstitial space and the relatively stable intracellular pH can influence the functions of cancer and stromal cells and their interaction with the extracellular matrix. We describe radiopharmaceutical probes for positron emission tomography (PET) that exploits the increasingly used concept of pH-dependent intratumorally cleavage of PET-tracer to release functional moieties. The radiopharmaceuticals are based on [18F]FDG, a PET tracer, routinely used, and substituents that are pH-dependently cleaved. Utilizing preclinical models, we were able to visualize small pH differences in the acidic TME of different tumors with [18F]FDG-4-methoxybenzylamine ([18F]FDG-4MBA). In vivo studies were in line with in vitro results and showed that the hemiaminal bond between FDG and a substitute is cleaved at slightly acidic pH and leads to pH dependent radiotracer uptake. In vivo neutralization of the acidic extracellular tumor pH by sodium bicarbonate treatment prevents pH-dependent cleavage of [18F]FDG-4MBA and a resulting decrease of uptake. The determination of pH differences in acidic TME may serve as a novel marker for various questions such as regulation of the response to immunotherapies. Notably, even small pH differences in the acidic TME of different tumors, in the same in vivo model, could be visualized. This is the first preclinical study to show that it is possible to visualize small pH differences in the TME of different tumors in the same mouse using hemiaminal bound [18F]FDG. Due to the facile tracer synthesis and application, this system could be well suited for translation into clinical studies to develop new strategies of pH regulation to improve the efficacy of immunotherapy in cancer patients. graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/624628v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1c338c8org.highwire.dtl.DTLVardef@1c4fc67org.highwire.dtl.DTLVardef@197036aorg.highwire.dtl.DTLVardef@1613fa2_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2024

Regulation of bicoid mRNA throughout oogenesis and early embryogenesis impacts protein gradient formation

The transcription factor Bicoid (Bcd) protein guides early Drosophila patterning and is the best-characterised morphogen. The source of the morphogen, bcd mRNA, is maternally deposited during oogenesis and localised to the anterior pole of the mature oocyte. While the spatiotemporal interpretation of the Bcd morphogen gradient has been intensely studied, when and where Bcd protein is produced and how this protein gradient is dynamically shaped remains contentious. Here, we use the SunTag reporter system to quantitatively examine the spatiotemporal profile of bcd mRNA translation in vivo. We show that association with Processing bodies (P bodies) in mature oocytes prevent premature bcd mRNA translation. Following egg activation, bcd mRNA dissociates from P bodies and translation is observed at the anterior pole. Translation remains restricted to the anterior domain throughout early development, even after nuclear migration in the syncytial blastoderm. At cellularisation, translation ceases and the remaining bcd mRNA associates with reformed P bodies, which appear to block any further translation. We use these observations to create a new modified source-diffusion-degradation model of Bcd gradient formation that has spatiotemporally varying production. Overall, our study reveals that bcd mRNA translation is tightly controlled in space and time during oogenesis and early embryogenesis.

developmental biology↗

bioRxiv2023

Structural adaptability and surface activity oftardigrade-inspired peptides

Tardigrades are unique micro-animals that withstand harsh conditions, such as extreme temperatures and desiccation. Recently, it was found that specific cytoprotective proteins are essential for ensuring this high environmental tolerance. In particular, cytoplasmic abundant heat soluble (CAHS) proteins, which are intrinsically disordered, adopt more ordered conformations upon desiccation, and are involved in the vitrification of the cytoplasm. The design and synthesis short peptides capable of mimicking the structural behavior (and thus the cytoprotective properties) of CAHS proteins would be beneficial for potential biomedical applications, including the development of novel heat-resistant preservatives for sensitive drug formulations. As a first step in this direction, we selected several model peptides of varying lengths derived from the conserved CAHS motifs 1 and 2, which are part of the intrinsically disordered CAHS-c2 region. We then studied their structures using circular dichroism and linear and two-dimensional infrared spectroscopy in the presence of the desolvating agent TFE (2,2,2-trifluoroethanol), which mimics desiccation. We found that the CAHS model peptides are mostly disordered at 0% TFE (a result that we confirmed by molecular dynamics simulations), but adopt a more -helical structure upon the addition of the desolvating agent, similar to what is observed for full CAHS proteins. Additionally, we employed sum frequency generation to investigate the surface activity of the peptides at the air/water interface to mimic a partial dehydration effect. Interestingly, all model peptides are surface active and also adopt a helical structure at the air/water interface. Thus, the selected sequences represent promising model peptides that show similarities in the physicochemical behavior to full CAHS proteins. Our results also suggest that arginine might be a crucial element in defining the strong propensity of these peptides to adopt a helical structure. In the future, the use CAHS model peptides to design new synthetic peptide-based materials could make it possible to mimic and exploit the cytoprotective properties of naturally occurring tardigrade proteins. SIGNIFICANCETardigrades are micro-animals that can survive extreme conditions such as desiccation and high temperatures. Recent work has shown that this capability is related to the presence of specific proteins that can remodel in order to protect the organisms cells. Mimicking this behavior using small peptides that preserve the structural properties of the full proteins is highly desirable in potential biomedical applications, such as the storage of heat-sensitive drugs. Here, we study the structural properties of model peptides derived from the conserved region of cytoplastic tardigrade proteins, and show that these peptides preserve some of the conformational behavior of the full protein under drying conditions. These peptides can therefore be used as a starting point for the design of synthetic model systems based on tardigrade-inspired peptides for tailored applications.

biochemistry↗

bioRxiv2023

Discovery of New Broad-Spectrum Anti-Infectives for Eukaryotic Pathogens Using Bioorganometallic Chemistry

Drug resistance observed with many anti-infectives clearly highlights the need for new broad-spectrum agents to treat especially neglected tropical diseases (NTDs) caused by eukaryotic parasitic pathogens including fungal infections. Since these diseases target the most vulnerable communities who are disadvantaged by health and socio-economic factors, new agents should be, if possible, easy-to-prepare to allow for commercialization based on their low cost. In this study, we show that simple modification of one of the most well-known antifungal drugs, fluconazole, with organometallic moieties not only improves the activity of the parent drug but also broadens the scope of application of the new derivatives. These compounds were highly effective in vivo against pathogenic fungal infections and potent against parasitic worms such as Brugia, which causes lymphatic filariasis and Trichuris, one of the soil-transmitted helminths that infects millions of people globally. Notably, the identified molecular targets indicate a mechanism of action that differs greatly from the parental antifungal drug, including targets involved in biosynthetic pathways that are absent in humans, offering great potential to expand our armamentarium against drug-resistant fungal infections and NTDs targeted for elimination by 2030. Overall, the discovery of these new compounds with broad-spectrum activity opens new avenues for the development of treatments for several current human infections, either caused by fungi or by parasites, including other NTDs, as well as newly emerging diseases. ONE-SENTENCE SUMMARYSimple derivatives of the well-known antifungal drug fluconazole were found to be highly effective in vivo against fungal infections, and also potent against the parasitic nematode Brugia, which causes lymphatic filariasis and against Trichuris, one of the soil-transmitted helminths that infects millions of people globally.

pharmacology and toxicology↗

bioRxiv2023

Dissociable control of motivation and reinforcement by distinct ventral striatal dopamine receptors

Dopamine release in striatal circuits, including the nucleus accumbens (NAc), tracks separable features of reward such as motivation and reinforcement. However, the cellular and circuit mechanisms by which dopamine receptors transform dopamine release into distinct constructs of reward remain unclear. Here, we show that dopamine D3 receptor (D3R) signaling in the NAc drives motivated behavior by regulating local NAc microcircuits. Furthermore, D3Rs co-express with dopamine D1 receptors (D1Rs), which regulate reinforcement, but not motivation. Paralleling dissociable roles in reward function, we report non-overlapping physiological actions of D3R and D1R signaling in NAc neurons. Our results establish a novel cellular framework wherein dopamine signaling within the same NAc cell type is physiologically compartmentalized via actions on distinct dopamine receptors. This structural and functional organization provides neurons in a limbic circuit with the unique ability to orchestrate dissociable aspects of reward-related behaviors that are relevant to the etiology of neuropsychiatric disorders.

neuroscience↗

bioRxiv2020

Antiviral activity of plant juices and green tea against SARS-CoV-2 and influenza virus in vitro

Many plant juices, extracts and teas have been shown to possess antiviral activity. We here analyzed the virucidal activity of black chokeberry (Aronia melanocarpa), pomegranate (Punica granatum), and elderberry (Sambucus nigra) juice, as well as green tea (Camellia sinensis) against different respiratory viruses. We found that all tested plant derived products effectively inactivated influenza virus, whereas only chokeberry juice diminished SARS-CoV-2 and vaccinia virus infectivity. None of the products inactivated non-enveloped human adenovirus type 5. Thus, black chokeberry juice exerts virucidal activity against different enveloped viral pathogens under in vitro conditions. Whether application of virucidal juices or green tea as oral rinses may lower viral loads in the oral cavity in vivo remains to be evaluated.

microbiology↗

bioRxiv2020

IFITM proteins promote SARS-CoV-2 infection in human lung cells

Interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) are thought to restrict numerous viral pathogens including severe acute respiratory syndrome coronaviruses (SARS-CoVs). However, most evidence comes from single-round pseudovirus infection studies of cells that overexpress IFITMs. Here, we verified that artificial overexpression of IFITMs blocks SARS-CoV-2 infection. Strikingly, however, endogenous IFITM expression was essential for efficient infection of genuine SARS-CoV-2 in human lung cells. Our results indicate that the SARS-CoV-2 Spike protein interacts with IFITMs and hijacks them for efficient viral entry. IFITM proteins were expressed and further induced by interferons in human lung, gut, heart and brain cells. Intriguingly, IFITM-derived peptides and targeting antibodies inhibited SARS-CoV-2 entry and replication in human lung cells, cardiomyocytes and gut organoids. Our results show that IFITM proteins are important cofactors for SARS-CoV-2 infection of human cell types representing in vivo targets for viral transmission, dissemination and pathogenesis and suitable targets for therapeutic approaches.

microbiology↗

bioRxiv2020

Alpha-1 antitrypsin inhibits SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). To identify factors of the respiratory tract that suppress SARS-CoV-2, we screened a peptide/protein library derived from bronchoalveolar lavage, and identified 1-antitrypsin (1-AT) as specific inhibitor of SARS-CoV-2. 1-AT targets the viral spike protein and blocks SARS-CoV-2 infection of human airway epithelium at physiological concentrations. Our findings show that endogenous 1-AT restricts SARS-CoV-2 and repurposes 1-AT-based drugs for COVID-19 therapy.

microbiology↗