Biology subjects

Moritz, M.

Publications and source records attributed to Moritz, M..

9 recordsLinked to original sources

bioRxiv2025

TSP1/TGF-β1 drives arachidonic acid metabolism to orchestrate neutrophil swarming

Neutrophil swarming has emerged as a conserved multicellular behaviour observed across tissues and pathological contexts. Yet, the molecular cues and the spatially coordinated cellular circuits that drive the process of neutrophil swarming leading to cluster formation remain poorly understood. Here, we combine spatial proteomics and lipid profiling in a model of urinary tract infection to define the epithelial-immune circuits driving neutrophil cluster formation. We identify thrombospondin-1 (TSP1)-mediated activation of transforming growth factor beta 1 (TGF-{beta}1) as key epithelial signal licensing neutrophil clustering and enhancing bacterial control. Spatial lipid analysis further reveals that TSP1/TGF-{beta}1 signalling locally activates arachidonic acid metabolism in epithelial neutrophils, with 5-lipoxygenase dependent leukotriene synthesis required for swarm formation and infection clearance. These findings uncover a spatially coordinated defence mechanism in which epithelial-derived TSP1/TGF-{beta}1 engages neutrophil lipid metabolism to orchestrate neutrophil swarming behaviour and reinforce antibacterial immunity. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/688397v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@114ea92org.highwire.dtl.DTLVardef@345244org.highwire.dtl.DTLVardef@10520baorg.highwire.dtl.DTLVardef@1a7c0fe_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO C_FIG

immunology↗

bioRxiv2025

Infrared Laser Sampling of Low Volumes Reveals Marker Lipids in Palatine Tonsil Carcinoma via Shotgun Lipidomics

Complete surgical resection is essential for oropharyngeal squamous cell carcinoma (OPSCC) therapy, underscoring the need for improved intraoperative margin assessment. To advance in-vivo diagnostics of OPSCC, Nanosecond infrared laser (NIRL) tissue sampling combined with shotgun lipidomic analysis reveals lipidome differences between OPSCC tissue and adjacent healthy tissue. Ablations were performed on tonsil squamous cell carcinoma on n=28 samples from 11 patients with an established chamber setup and a subset of n=6 samples from three patients with a custom-made handheld applicator. Welchs t-test results (p=0.05, two-fold change) revealed a similar OPSCC lipid profile in 7 of 11 patients. Potential tumor lipid markers were identified as consistently significantly increased, despite biological heterogeneity of the samples, underscoring their potential diagnostic value. Tissue ablation with a custom-made handheld applicator coupled to a laser fiber was successful and the lipidomic analysis was consistent to the chamber setup. Although our setup is currently limited by an ablation time exceeding one minute, this study demonstrates the potential of the handheld applicator for future applications such as endoscopy or intraoperative diagnostics.

cancer biology↗

bioRxiv2024

Co-activation of LIN28A and CTNNB1 disturbs cortical neuronal migration and pia mater integrity

Developmental signalling pathways act in stage and tissue dependent relation and mis-activation can drive tumour formation. The RNA-binding protein LIN28A maintains stemness and is overexpressed in embryonal brain tumours. Activating mutations of CTNNB1 - the WNT pathway effector - have been reported in respective brain tumours. The aim of this study was to investigate the interplay of these oncogenic proteins during embryonal brain development. The combination of both oncogenic factors did not lead to brain tumour formation but resulted in disturbed lamination and impaired cell migration in the cerebral cortex. Spatially resolved proteome analysis revealed imbalances of the extracellular matrix protein LAMB1 and its receptors RPSA and ITGB1 accompanied by a porous pial border and overmigration of neural cells. Cajal-Retzius cells were misplaced in deeper cortex regions without affecting general REELIN levels and additional reduced levels of -DYSTROGLYCAN. Taken together, the interplay of LIN28A and CTNNB1 resulted in a cortical migration disorder showing histomorphological and molecular similarities to human Cobblestone lissencephaly (type 2), highlighting novel implications of the oncogene LIN28A in extracellular matrix integrity.

neuroscience↗

bioRxiv2023

Assay for characterizing adsorption-properties of surfaces (APS) sample preparation prior to quantitative omics

Analytes during their journey from their natural sources to their identification and quantification are prone to adsorption to surfaces before they enter an analytical instrument, causing false quantities. This problem is especially severe in diverse omics. Here, thousands of analytes with a broad range of chemical properties and thus different affinities to surfaces are quantified within a single analytical run. For quantifying adsorption effects caused by surfaces of sample handling tools, an assay was developed, applying LC-MS/MS-based differential bottom-up proteomics and as probe a reference mixture of thousands of tryptic peptides, covering a broad range of chemical properties. The assay was tested by investigating the adsorption properties of several vials composed of polypropylene, including low-protein-binding polypropylene vials, borosilicate glass vials and low-retention glass vials. In total 3531 different peptides were identified and quantified across all samples and therefore used as probes. A significant number of hydrophobic peptides adsorbed on polypropylene vials. In contrast, only very few peptides adsorbed to low-protein-binding polypropylene vials. The highest number of peptides adsorbed to glass vials, driven by electrostatic as well as hydrophobic interactions. Calculation of the impact of the adsorption of peptides on differential quantitative proteomics showed significant false results. In summary, the new assay is suitable to characterize adsorption properties of surfaces getting into contact with analytes during sample preparation, thereby giving the opportunity to find parameters for minimizing false quantities. Insert Table of Contents artwork here O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=106 SRC="FIGDIR/small/551632v3_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@bafb12org.highwire.dtl.DTLVardef@1b98219org.highwire.dtl.DTLVardef@c3b45org.highwire.dtl.DTLVardef@1074180_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2021

Tau interactome mapping reveals dynamic processes in synapses and mitochondria associated with neurodegenerative disease

Tau (MAPT) drives neuronal dysfunction in Alzheimers disease (AD) and other tauopathies. To dissect the underlying mechanisms, we combined an engineered ascorbic acid peroxidase (APEX) approach with quantitative affinity purification mass spectrometry (AP-MS) followed by proximity ligation assay (PLA) to characterize Tau interactomes modified by neuronal activity and mutations that cause frontotemporal dementia (FTD) in human induced pluripotent stem cell (iPSC)-derived neurons. We established activity-dependent interactions of Tau with presynaptic vesicle proteins during Tau secretion and mapped the exact APEX-tau-induced biotinylated tyrosines to the cytosolic domains of the interacting vesicular proteins. We showed that FTD mutations impair bioenergetics and markedly diminished Taus interaction with mitochondria proteins, which were downregulated in AD brains of multiple cohorts and correlated with disease severity. These multi-modal and dynamic Tau interactomes with unprecedented spatiotemporal resolution shed novel insights into Taus role in neuronal function and disease-related processes with potential therapeutic targets to block Tau-mediated pathogenesis.

neuroscience↗

bioRxiv2021

CryoEM and AI reveal a structure of SARS-CoV-2 Nsp2, a multifunctional protein involved in key host processes.

The SARS-CoV-2 protein Nsp2 has been implicated in a wide range of viral processes, but its exact functions, and the structural basis of those functions, remain unknown. Here, we report an atomic model for full-length Nsp2 obtained by combining cryo-electron microscopy with deep learning-based structure prediction from AlphaFold2. The resulting structure reveals a highly-conserved zinc ion-binding site, suggesting a role for Nsp2 in RNA binding. Mapping emerging mutations from variants of SARS-CoV-2 on the resulting structure shows potential host-Nsp2 interaction regions. Using structural analysis together with affinity tagged purification mass spectrometry experiments, we identify Nsp2 mutants that are unable to interact with the actin-nucleation-promoting WASH protein complex or with GIGYF2, an inhibitor of translation initiation and modulator of ribosome-associated quality control. Our work suggests a potential role of Nsp2 in linking viral transcription within the viral replication-transcription complexes (RTC) to the translation initiation of the viral message. Collectively, the structure reported here, combined with mutant interaction mapping, provides a foundation for functional studies of this evolutionary conserved coronavirus protein and may assist future drug design.

biophysics↗

bioRxiv2020

Fragment binding to the Nsp3 macrodomain of SARS-CoV-2 identified through crystallographic screening and computational docking

The SARS-CoV-2 macrodomain (Mac1) within the non-structural protein 3 (Nsp3) counteracts host-mediated antiviral ADP-ribosylation signalling. This enzyme is a promising antiviral target because catalytic mutations render viruses non-pathogenic. Here, we report a massive crystallographic screening and computational docking effort, identifying new chemical matter primarily targeting the active site of the macrodomain. Crystallographic screening of diverse fragment libraries resulted in 214 unique macrodomain-binding fragments, out of 2,683 screened. An additional 60 molecules were selected from docking over 20 million fragments, of which 20 were crystallographically confirmed. X-ray data collection to ultra-high resolution and at physiological temperature enabled assessment of the conformational heterogeneity around the active site. Several crystallographic and docking fragment hits were validated for solution binding using three biophysical techniques (DSF, HTRF, ITC). Overall, the 234 fragment structures presented explore a wide range of chemotypes and provide starting points for development of potent SARS-CoV-2 macrodomain inhibitors.

biochemistry↗

bioRxiv2020

XMAP215 and γ-tubulin additively promote microtubule nucleation in purified solutions

Microtubule nucleation is spatiotemporally regulated in cells by several molecules, including the template {gamma}-tubulin and the polymerase XMAP215. Recently, XMAP215 and the {gamma}-tubulin ring complex were reported to function synergistically, and this synergy was hypothesized to be due to direct binding between XMAP215 and {gamma}-tubulin. Here, we address this hypothesis by 1) probing domain requirements for XMAP215 to promote microtubule nucleation and 2) testing whether XMAP215 functions synergistically with {gamma}-tubulin in the absence of the other ring complex proteins. We confirm that {gamma}-tubulin and XMAP215 are classically defined nucleators that reduce the nucleation lag seen in bulk tubulin assembly. Then, using deletion constructs, we show that XMAP215s ability to nucleate microtubules in purified solutions correlates with its ability to elongate existing microtubules and does not depend on the number of TOG domains. Finally, we show that XMAP215 and {gamma}-tubulin promote {beta}-tubulin assembly in an additive, not synergistic, manner. Thus, their modes of action during microtubule nucleation are distinct, and the synergy reported between XMAP215 and the {gamma}-tubulin ring complex is not due to {gamma}-tubulin alone.

biochemistry↗

bioRxiv2019

Microtubules form by progressively faster tubulin accretion, not by nucleation-elongation

Microtubules are dynamic polymers that play fundamental roles in all eukaryotes. Despite their importance, how new microtubules form is poorly understood. Textbooks have focused on variations of a nucleation-elongation mechanism in which monomers rapidly equilibrate with an unstable oligomer (nucleus) that limits the rate of polymer formation; once formed, the polymer then elongates efficiently from this nucleus by monomer addition. Such models faithfully describe actin assembly, but they fail to account for how more complex polymers like hollow microtubules assemble. Here we articulate a new model for microtubule formation that has three key features: i) microtubules initiate via rectangular, sheet-like structures which grow faster the larger they become; ii) the dominant pathway proceeds via accretion, stepwise addition of longitudinal or lateral layers; iii) a straightening penalty to account for the energetic cost of tubulins curved-to-straight conformational transition. This model can quantitatively fit experimental assembly data, providing new insights into biochemical determinants and assembly pathways for microtubule nucleation.

cell biology↗