Biology subjects

Brueggemann, Y.

Publications and source records attributed to Brueggemann, Y..

8 recordsLinked to original sources

bioRxiv2026

Oncomimetic β-catenin activity onset, duration and region defines aberrant intestinal development

In early intestinal carcinogenesis, adenoma formation is commonly initiated by loss-of-function mutations in a tumor suppressor that lead to oncoprotein gain-of-function, like in the tumor suppressor-oncoprotein pair APC-{beta}-catenin. Small intestinal organoids provide an in vitro system to study consequences of such mutations on tissue organization. However, conventional genetic manipulations do not allow precise control over the onset and duration of oncoprotein activity to study their influence on tissue transformation. Furthermore, homogenous tissues of clonal genetic models do not readily capture cellular interaction among mutated and neighboring wildtype tissue during early transformation. To mimic oncogenic activation of {beta}-catenin, we established a chemical-(opto)genetic approach to gain bio-orthogonal acute, spatial and temporal control over {beta}-catenin oncoprotein stability and relate oncoprotein levels to morphological development of mouse small intestinal organoids. We identified aberrant phenotypes that result from bio-orthogonally induced oncoprotein activity but persist even after oncoprotein depletion. Furthermore, local activation of oncomimetic {beta}-catenin activity within the stem cell niche leads to aberrant differentiation during homeorhesis and homeostasis, recapitulating early events of tissue transformation.

cancer biology↗

bioRxiv2026

Yellow fever vaccine propagation in primary human hepatocytes triggers antiviral and cytolytic responses

Yellow fever virus (YFV) infection can cause severe-to-fatal liver damage in humans, while immunization with the attenuated 17D vaccine strain has an excellent safety record, priming protective host immunity in the absence of pathology. To investigate virus-host correlates associated with these differential clinical outcomes, we combined YFV genome-level evolutionary analyses with investigations of vaccine and virulent strain hepatotropism. Evolutionary analyses confirmed purifying selection is the dominant force driving global YFV genome divergence, with functional constraints associated with the YFV transmission cycle selecting against vaccine attenuating mutations in virulent strains. In immune deficient hepatoma cells, 17D exhibited enhanced early propagation, spreading and apoptosis induction when compared to virulent strains. Ex vivo infections performed in primary human hepatocytes (PHH) from multiple donors confirmed robust propagation of both 17D and virulent YFV strains. RNA-sequencing revealed consistent and shared induction of IFNB and IFNL1-4, modulating overlapping gene programs associated with antiviral responses, immunity, chemotaxis and inflammation, cell-death, metabolic reprogramming and protein translation. Subtle differences in virion production kinetics and the magnitude and tempo of PHH transcriptional responses were observed. Antiviral responses to 17D were activated earlier while responses to virulent YFV were delayed but enhanced, mirroring virus propagation kinetics. More broadly, cellular responses to YFV infection are likely dominated by paracrine IFN signalling, with enriched LRP1 expression coupled with impaired IFN production in PHH contributing to YFVs robust hepatotropism. In summary, we demonstrate comparable propagation kinetics and PHH transcriptional responses to vaccine and virulent YFV strains, highlighting impaired hepatotropism is not a correlate of vaccine attenuation. These data imply that unknown barriers restrict liver access and associated organ pathology upon vaccination with 17D.

microbiology↗

bioRxiv2023

Hepatitis C virus cell culture adaptive mutations enhance cell culture propagation by multiple mechanisms but boost antiviral responses in primary human hepatocytes

Hepatitis C virus (HCV) infection progresses to chronicity in the majority of infected individuals. Its high intra-host genetic variability enables HCV to evade the continuous selection pressure exerted by the host, contributing to persistent infection. Utilizing a cell culture adapted HCV population (p100pop) which exhibits increased replicative capacity in various liver cell lines, this study investigated virus and host determinants which underlie enhanced viral fitness. Characterization of a panel of molecular p100 clones revealed that cell culture adaptive mutations optimize a range of virus-host interactions, resulting in expanded cell tropism, altered dependence on the cellular co-factor micro-RNA 122 and increased rates of virus spread. On the host side, comparative transcriptional profiling of hepatoma cells infected either with p100pop or its progenitor virus revealed that enhanced replicative fitness correlated with activation of endoplasmic reticulum stress signaling and the unfolded protein response. In contrast, infection of primary human hepatocytes with p100pop led to a mild attenuation of virion production which correlated with a greater induction of cell-intrinsic antiviral defense responses. In summary, long-term passage experiments in cells where selective pressure from innate immunity is lacking improves multiple virus-host interactions, enhancing HCV replicative fitness. However, this study further indicates that HCV has evolved to replicate at low levels in primary human hepatocytes to minimize innate immune activation, highlighting that an optimal balance between replicative fitness and innate immune induction is key to establishing persistence. Author SummaryHCV infection remains a global health burden with 58 million people currently chronically infected. However, the detailed molecular mechanisms which underly persistence are incompletely defined. We utilized a long-term cell culture adapted HCV, exhibiting enhanced replicative fitness in different human liver cell lines, in order to identify molecular principles by which HCV optimizes its replication fitness. Our experimental data revealed that cell culture adaptive mutations confer changes in the host response and usage of various host factors. The latter allows functional flexibility at different stages of the viral replication cycle. However, increased replicative fitness resulted in an increased activation of the innate immune system, which likely poses boundary for functional variation in authentic hepatocytes, explaining the observed attenuation of the adapted virus population in primary hepatocytes.

molecular biology↗

bioRxiv2023

Targeting cellular cathepsins inhibits hepatitis E virus infection

Background and AimsThe hepatitis E virus (HEV) is estimated to be responsible for 70,000 deaths annually, yet therapy options remain limited. In the pursuit of effective antiviral therapies, targeting viral entry holds promise and has proven effective for other hepatotropic viruses. However, the precise mechanisms and host factors required during HEV entry remain unclear. Cellular proteases have emerged as a class of host factors required for viral surface protein activation and productive cell entry by many viruses. Hence, we investigated the functional requirement and therapeutic potentials of cellular proteases during HEV infection. Approach and ResultsUsing our recently established HEV cell culture model and subgenomic HEV replicons, we found that blocking lysosomal cathepsins (CTS) with small molecule inhibitors, impedes HEV infection without affecting replication. Most importantly, the pan-cathepsin inhibitor K11777 robustly suppressed HEV infections with an EC50 of [~] 0.01 nM. Inhibition by K11777, devoid of notable toxicity in hepatoma cells until micromolar concentrations, was also observed in differentiated HepaRG and ex vivo in primary human hepatocytes. Furthermore, through time-of-addition experiments, we confirmed that HEV entry is potently blocked by inhibition of cathepsins and cathepsin L (CTSL) knockout cells were less permissive to HEV suggesting that CTSL is critical for HEV infection. ConclusionsIn summary, our study highlights the pivotal role of lysosomal cathepsins, especially CTSL, in the HEV entry process. The profound anti-HEV efficacy of the pan-cathepsin inhibitor, K11777, especially with its notable safety profile in primary cells, further underscores its potential as a promising therapeutic candidate.

cell biology↗

bioRxiv2021

Comparable environmental stability and disinfection profiles of the currently circulating SARS-CoV-2 variants of concern B.1.1.7 and B.1.351

The emergence of novel SARS-CoV-2 B.1.1.7 and B.1.351 variants of concern with increased transmission dynamics has raised questions regarding stability and disinfection of these viruses. In this study, we analyzed surface stability and disinfection of the currently circulating SARS-CoV-2 variants B.1.1.7 and B.1.351 compared to the wildtype. Treatment with heat, soap and ethanol revealed similar inactivation profiles indicative of a comparable susceptibility towards disinfection. Furthermore, we observed comparable surface stability on steel, silver, copper and face masks. Overall, our data support the application of currently recommended hygiene concepts to minimize the risk of B.1.1.7 and B.1.351 transmission.

microbiology↗

bioRxiv2021

A realistic touch-transfer method reveals low risk of transmission for SARS-CoV-2 by contaminated coins and bank notes

The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has created a significant threat to global health. While respiratory aerosols or droplets are considered as the main route of human-to-human transmission, secretions expelled by infected individuals can also contaminate surfaces and objects, potentially creating the risk of fomite-based transmission. Consequently, frequently touched objects such as paper currency and coins have been suspected as a potential transmission vehicle. To assess the risk of SARS-CoV-2 transmission by banknotes and coins, we examined the stability of SARS-CoV-2 and bovine coronavirus (BCoV), as surrogate with lower biosafety restrictions, on these different means of payment and developed a touch transfer method to examine transfer efficiency from contaminated surfaces to skin. Although we observed prolonged virus stability, our results, including a novel touch transfer method, indicate that the transmission of SARS-CoV-2 via contaminated coins and banknotes is unlikely and requires high viral loads and a timely order of specific events.

microbiology↗

bioRxiv2021

A genome-wide CRISPR screen identifies interactors of the autophagy pathway as conserved coronavirus targets

Over the past 20 years, the emergence of three highly pathogenic coronaviruses (CoV) - SARS-CoV, MERS-CoV, and most recently SARS-CoV-2 - has shown that CoVs pose a serious risk to human health and highlighted the importance of developing effective therapies against them. Similar to other viruses, CoVs are dependent on host factors for their survival and replication. We hypothesized that evolutionarily distinct CoVs may exploit similar host factors and pathways to support their replication cycle. Here, we conducted two independent genome-wide CRISPR/Cas9 knockout screens to identify pan-CoV host factors required for the replication of both endemic and emerging CoVs, including the novel CoV SARS-CoV-2. Strikingly, we found that several autophagy-related genes, including the immunophilin FKBP8, TMEM41B, and MINAR1, were common host factors required for CoV replication. Importantly, inhibition of the immunophilin family with the compounds Tacrolimus, Cyclosporin A, and the non-immunosuppressive derivative Alisporivir, resulted in dose-dependent inhibition of CoV replication in primary human nasal epithelial cell cultures that resemble the natural site of virus replication. Overall, we identified host factors that are crucial for CoV replication and demonstrate that these factors constitute potential targets for therapeutic intervention by clinically approved drugs.

microbiology↗

bioRxiv2018

Interdependence of EGFR with PTPs on juxtaposed membranes generates a growth factor sensing and responding network

The proto-oncogenic epidermal growth factor receptor (EGFR) is a tyrosine kinase whose sensitivity to growth factors (GFs) and signal duration determines cellular behavior. We resolve how EGFRs response to epidermal growth factor (EGF) originates from dynamically established recursive interactions with spatially organized protein tyrosine phosphatases (PTPs). Opposed genetic PTP perturbations enabled identification of receptor-like PTPRG/J at the plasma membrane (PM) and endoplasmic reticulum (ER) associated PTPN2 as the major EGFR dephosphorylating activities. Imaging spatial-temporal PTP reactivity then revealed that vesicular trafficking establishes a spatially-distributed negative feedback with PTPN2 that determines signal duration, whereas single cell dose-response analysis uncovered a ROS-mediated toggle switch between autocatalytically activated monomeric EGFR and the tumor suppressor PTPRG that governs EGFRs sensitivity to EGF. Vesicular recycling of monomeric EGFR unifies the interactions with these PTPs on juxtaposed membranes, dynamically generating a network architecture that can sense and respond to time varying growth factor signals.

systems biology↗