Biology subjects

Meyer, T.

Publications and source records attributed to Meyer, T..

At least 19 recordsLinked to original sources

bioRxiv2026

YAP/TAZ-controlled ERK dynamics coordinate progenitor expansion and differentiation commitment

Progenitor cells must proliferate to expand the cell population, yet terminal differentiation requires this proliferative state to end. How signaling controls the duration of this proliferative window remains poorly understood. Using adipogenesis and live single-cell imaging of differentiation, cell-cycle, and ERK-activity reporters, we show that YAP and TAZ coordinate progenitor expansion with differentiation commitment by regulating ERK dynamics. YAP/TAZ maintain cells in a fluctuating high-ERK state that promotes proliferation while actively keeping the differentiation driver PPARG below the threshold for irreversible commitment. Crucially, this differentiation block is not explained by proliferation alone: inhibiting CDK4/6 or AKT suppressed proliferation without restoring differentiation, whereas MEK-ERK inhibition restored differentiation even when YAP/TAZ activity remained high. As YAP/TAZ activity decreases, dampened ERK fluctuations trigger PPARG activation. These findings support a self-limiting model in which YAP/TAZ-driven progenitor expansion progressively increases cell density and contact-dependent Hippo signaling, reducing YAP/TAZ activity and terminating the proliferative phase. Consequently, transient YAP/TAZ activation expands the progenitor pool while preserving subsequent differentiation, whereas sustained activation suppresses commitment. Together, these findings identify YAP/TAZ-controlled ERK dynamics as the nexus coordinating progenitor expansion with terminal differentiation and suggest that slower density-dependent Hippo feedback may set the duration of this proliferative window to regulate differentiated cell-number output.

cell biology↗

bioRxiv2026

Automatic deep learning-based segmentation and quantification of stented arterial cross-sections for morphometric analysis

Arterial vascular diseases, such as atherosclerosis, are among the most serious global health threats. In preclinical studies, morphometric analysis of histological arterial cross-sections is considered the gold standard for assessing vascular remodeling and the effectiveness of therapeutic interventions. However, morphometric analysis is usually performed manually, which is time-consuming, subjective, and requires significant user interaction. This paper presents a fully automated, operator-independent framework for the precise morphometric analysis of stented arterial cross-sections, extending the previously developed qHisto (quantitative histology) framework for the quantification of various histological components. A neural network for the segmentation of arterial structures was trained and evaluated using 819 cross-sections. In addition, a quantitative analysis of vascular morphology, fibrin area, and lumen asymmetry was performed using 72 cross-sections from coated and uncoated balloons. The model achieved high segmentation accuracy with a median Dice similarity coefficient of 0.892-0.996. Compared to manual evaluation, the system reduces analysis time by 90%, enabling efficient processing of large datasets. Furthermore, morphometric analysis with qHisto showed significant differences between coated and uncoated balloons, e.g. regarding lumen area (AUC = 0.86) and fibrin ratio (AUC = 0.94). Our developed framework enables fully automated, comprehensive and standardized analysis of histological arterial cross-sections. This helps to reduce time-consuming, repetitive manual assessments and thus facilitates research of disease mechanisms and treatment effects in preclinical studies.

pathology↗

bioRxiv2025

Spatiotemporal mapping of microscale stiffness during collagen polymerization and crosslinking by optical multifrequency time-harmonic elastography

Optical multifrequency time-harmonic elastography (OMTHE) was used for rapid mechanical characterization of extra-cellular matrix-derived collagen networks at micrometer resolution. OMTHE was optimized for point-wise shear wave excitation in small sample volumes and compared to tabletop magnetic resonance elastography (ttMRE) and optical intensity changes. Dynamic stiffening due to the fluid-gel transition during collagen polymerization and chemical crosslinking using glutaraldehyde was tracked by shear waves speed (SWS) at vibration frequencies between 3 and 10 kHz and frame rates up to 4 kHz. During collagen polymerization, after an initial lag phase, SWS increased on average 6 {+/-} 3 min earlier than optical density, suggesting that a load-bearing percolating fiber network was established before fibril thickening enhanced light scattering. In contrast, chemical crosslinking showed a lag-free, diffusion-driven SWS increase from 1.7 {+/-} 0.4 m/s to 2.5 {+/-} 0.5 m/s, matching the relative SWS change from ground-truth ttMRE. In conclusion, OMTHE provides a unique research tool that quantifies biomechanical property changes in small biological samples with spatiotemporal resolutions of micrometers and seconds. Key Results- Point-excitation OMTHE at microscopic resolution maps dynamic stiffness changes in collagen gels during polymerization and crosslinking at high frame rates. - Polymerization and crosslinking of collagen show distinct time courses with polymerization being in the order of minutes ahead of crosslinking. - Collagen stiffening due to polymerization precedes changes in optical density as seen by light microscopy.

biophysics↗

bioRxiv2025

Liver Viscosity Decreases Before the Onset of Fibrosis in Metabolic Dysfunction-Associated 1 Steatohepatitis (MASH)

Background and AimMetabolic dysfunction-associated steatohepatitis (MASH) is an increasingly prevalent condition worldwide, associated with biomechanical liver changes and detectable by magnetic resonance elastography (MRE). This study explored the pathophysiological features and their biomechanical manifestations at different stages of MASH in a mouse dietary model. MethodsUsing MRE on a clinical 3 Tesla MRI scanner, we measured liver stiffness, viscosity, fat fraction and water diffusion in 45 male mice. These values were correlated with histopathology and proteomics analyses to further characterize the liver microstructural and metabolic changes during MASH progression. ResultsWe found in a high-fat, low amino-acid model that early MASH was marked by fat accumulation and increasing inflammatory activity, while later stages showed a reduction in fat despite persistent inflammation. These changes in microstructure were associated with biomechanical adaptations, including a progressive decrease in hepatic viscosity and the water diffusion. Notably, viscosity was inversely correlated with lobular inflammation, cell adhesion, antioxidant activity, and metabolic adaptations such as enhanced ketone body synthesis. These findings, which precede the onset of fibrosis and tissue stiffening, show that tissue viscosity is highly sensitive to early microstructural and metabolic alterations in MASH. ConclusionSteatosis and inflammation significantly alter liver biophysical properties, particularly viscosity, in a mouse dietary model of MASH, even in the absence of fibrosis. These findings suggest that viscosity is a potential early and clinically translatable biomarker for the development and progression of MASH.

biophysics↗

bioRxiv2025

Resolving a paradox about how vision is transformed into familiarity

How is the act of seeing an image transformed into the memory that it has been seen? To investigate, we leveraged the systematic variation with which some images are better remembered than others, image memorability, to compare neural responses in inferotemporal cortex (ITC) and the hippocampus (HC) as macaque monkeys performed a single-exposure visual familiarity task. We found evidence for a two-stage algorithmic transformation from visual representations to familiarity, including a previously undescribed computational transformation of familiarity in the medial temporal lobe. At the first stage, more memorable images elicited more vigorous ITC firing-rate responses and stronger ITC familiarity signals (reflected as repetition suppression). This led to a counterintuitive intermingling of familiarity and memorability signals in ITC, but a representation that could be read out by a linear decoder. At the next stage, the medial temporal lobe selectively extracted ITC familiarity signals to produce a more isolated familiarity representation with minimal memorability modulation, reflected downstream in HC. These results shed light on how seeing is transformed into familiarity, and they establish the existence of a previously undescribed medial temporal lobe computation.

neuroscience↗

bioRxiv2025

Sharpened visual memory representations are reflected in inferotemporal cortex

Humans and other primates can robustly report whether theyve seen specific images before, even when those images are extremely similar to ones theyve previously seen. Multiple lines of evidence suggest that pattern separation computations in the hippocampus (HC) contribute to this behavior by shaping the fidelity of visual memory. However, unclear is whether HC uniquely determines memory fidelity or whether computations in other brain areas also contribute. To investigate, we recorded neural signals from inferotemporal cortex (ITC) and HC of two rhesus monkeys as they performed a memory task in which they judged whether images were novel or exactly repeated in the presence of visually similar lure images with a range of visual similarities. We found behavioral evidence for sharpening, reflected as memory performance that was nonlinearly transformed relative to a benchmark defined by visual representations in ITC. As expected, we found that behavioral sharpening aligned with visual memory representations in HC. Surprisingly, and unaccounted for by HC pattern separation proposals, we also found neural correlates of behavioral sharpening reflected in ITC. These results, coupled with further analysis of the data, suggest that ITC contributes to shaping the fidelity of visual memory in the transformation from visual processing to memory storage and signaling. SignificanceVisual recognition memories are stored with remarkable visual fidelity, allowing humans and other primates to distinguish images they have encountered from visually similar images they have not. This fidelity has long been attributed to computations in the hippocampus that sharpen visual representations before memory storage ("pattern separation"). Unclear is how this proposal aligns with other evidence that visual memories are stored within high-level visual cortex itself, before signals reach the hippocampus. Here we demonstrate that, like the hippocampus, inferotemporal cortex also reflects sharpened visual memory representations, suggesting that visual cortex contributes to shaping the visual fidelity of visual memory.

neuroscience↗

bioRxiv2025

Inactivation of CDK4/6, CDK2, and ERK in G1-phase triggers differentiation commitment

Terminal cell differentiation, a process vital for tissue development and regeneration where progenitor cells acquire specialized functions and permanently exit the cell cycle, is still poorly understood at the molecular level. Using live-cell imaging and adipogenesis as a model, we demonstrate that the initial stage involves a variable number of cell divisions driven by redundant CDK4/6 or CDK2 activation.. Subsequently, a delayed decrease in cyclin D1 and an increase in p27 levels leads to the attenuation of CDK4/6 and CDK2 activity. This results in G1 lengthening and the induction of PPARG, the master regulator of adipogenesis. PPARG then induces p21, and later p18, culminating in the irreversible inactivation of CDK4/6 and CDK2, and thus, permanent cell cycle exit. However, contrary to expectation, CDK inactivation alone is not sufficient to trigger commitment to differentiation and functional specialization; ERK inactivation is also required. Our study establishes that the coordinated activation and subsequent delayed inactivation of CDK4/6, CDK2, and ERK are crucial determinants for irreversible cell cycle exit and differentiation commitment in terminal cell differentiation.

cell biology↗

bioRxiv2024

Rewired type I IFN signaling is linked to age-dependent differences in COVID-19

Advanced age is the most important risk factor for severe disease or death from COVID-19, but a thorough mechanistic understanding of the molecular and cellular underpinnings is lacking. Multi-omics analysis of samples from SARS-CoV-2 infected persons aged 1 to 84 years, revealed a rewiring of type I interferon (IFN) signaling with a gradual shift from signal transducer and activator of transcription 1 (STAT1) to STAT3 activation in monocytes, CD4+ T cells and B cells with increasing age. Diversion of interferon IFN signaling was associated with increased expression of inflammatory markers, enhanced release of inflammatory cytokines, and delayed contraction of infection-induced CD4+ T cells. A shift from IFN-responsive germinal center B (GCB) cells towards CD69high GCB and atypical B cells corresponded to the formation of IgA in children while complement fixing IgG was dominant in adults. Our data provide a mechanistic basis for inflammation-prone responses to infections and associated pathology during aging. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=144 SRC="FIGDIR/small/619479v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@723896org.highwire.dtl.DTLVardef@e12b2aorg.highwire.dtl.DTLVardef@d8de22org.highwire.dtl.DTLVardef@1df96ec_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

Transient proliferation by reversible YAP-mediated increase of the cyclin D1/p27 ratio

Hippo-YAP signaling orchestrates epithelial tissue repair and is therefore an attractive target in regenerative medicine. Yet it is unresolved how YAP integrates with mitogen signaling and contact inhibition to control the underlying transient proliferative response. Here we show that reduced contact inhibition, increased mitogen signaling, and YAP-TEAD activation converge on increasing the nuclear cyclin D1/p27 protein ratio during G1 phase, towards a threshold ratio that dictates whether individual cells enter or exit the cell cycle. YAP increases this ratio indirectly, in concert with mitogen signaling, by increasing EGFR and other receptors that signal primarily through ERK. After a delay, contact inhibition suppresses YAP activity which gradually downregulates mitogen signaling and the cyclin D1/p27 ratio. Increasing YAP activity by ablating the suppressor Merlin/NF2 reveals a balancing mechanism in which YAP suppression and contact inhibition of proliferation can be recovered but only at higher local cell density. Thus, critical for tissue repair, robust proliferation responses result from the YAP-induced and receptor-mediated prolonged increase in the cyclin D1/p27 ratio, which is only reversed by delayed suppression of receptor signaling after contact inhibition of YAP.

cell biology↗

bioRxiv2024

High quality Bathyarchaeia MAGs from lignocellulose-impacted environments elucidate metabolism and evolutionary mechanisms.

The archaeal class Bathyarchaeia are widely and abundantly distributed in anoxic habitats. Metagenomic studies have suggested that they are mixotrophic, capable of CO2 fixation and heterotrophic growth, and involved in acetogenesis and lignin degradation. We analysed 35 Bathyarchaeia metagenome assembled genomes (MAGs), including the first complete circularized MAG (cMAG) of the Bathy-6 subgroup, from the metagenomes of three full scale pulp and paper mill anaerobic digesters and three laboratory methanogenic enrichment cultures maintained on pre-treated poplar. Thirty-three MAGs belong to the Bathy-6 lineage while two are from the Bathy-8 lineage. In our previous analysis of the microbial community in the pulp mill digesters, Bathyarchaeia were abundant and positively correlated to hydrogenotrophic and methylotrophic methanogenesis. Several factors likely contribute to the success of the Bathy-6 lineage compared to Bathy-8 in the reactors. The Bathy-6 genomes are larger than those of Bathy-8 and have more genes involved in lignocellulose degradation including carbohydrate-active enzymes (CAZymes) not present in the Bathy-8. Bathy-6 also share the Bathyarchaeal O-demethylase-system recently identified in Bathy-8. All the Bathy-6 MAGs had numerous membrane-associated pyrroloquinoline quinone-domain (PQQ) proteins that we suggest are involved in lignin modification or degradation, together with Radical-SAM and Rieske domain proteins, and AA2, AA3, and AA6-family oxidoreductases. We also identified a complete B12 synthesis pathway and a complete nitrogenase gene locus. Finally, comparative genomic analyses revealed that Bathyarchaeia genomes are dynamic and have interacted with other organisms in their environments through gene transfer to expand their gene repertoire.

genomics↗

bioRxiv2024

Transfer RNA acetylation regulates in vivo mammalian stress signaling

Transfer RNA (tRNA) modifications are crucial for protein synthesis, but their position-specific physiological roles remain poorly understood. Here we investigate the impact of N4-acetylcytidine (ac4C), a highly conserved tRNA modification, using a Thumpd1 knockout mouse model. We find that loss of Thumpd1-dependent tRNA acetylation leads to reduced levels of tRNALeu, increased ribosome stalling, and activation of eIF2 phosphorylation. Thumpd1 knockout mice exhibit growth defects and sterility. Remarkably, concurrent knockout of Thumpd1 and the stress-sensing kinase Gcn2 causes penetrant postnatal lethality, indicating a critical genetic interaction. Our findings demonstrate that a modification restricted to a single position within type II cytosolic tRNAs can regulate ribosome-mediated stress signaling in mammalian organisms, with implications for our understanding of translation control as well as therapeutic interventions.

developmental biology↗

bioRxiv2024

The long noncoding RNA lnc-FANCI-2 restricts RAS signaling and phosphorylation of Akt and Erk in HPV16-infected cervical cancer cells

We recently discovered the expression of a long noncoding RNA, lnc-FANCI-2, coinciding with cervical lesion progression from CIN1, CIN2-3 to cervical cancer. Viral E7 of high-risk HPVs and host transcription factor YY1 are two major factors promoting lnc-FANCI-2 expression. To explore possible roles of lnc-FANCI-2 in HPV-induced cervical carcinogenesis, we ablated the expression of lnc-FANCI-2 in the HPV16-positive cervical cancer cell line, CaSki. Knock-out (KO) single cell clones expressed HPV16 oncogenes normally but displayed altered cell morphology and proliferation when compared with the parental cells. Proteomic profiling of cytosolic and secreted proteins from the parental and KO cells showed that lnc-FANCI-2 regulates expression of a subset of cell soluble receptors responsible for cell signaling, epithelial mesenchymal transition, and IFN responses. RNA-seq analyses revealed that, relative to the parental cells, lnc-FANCI-2 KO cells exhibited significantly increased RAS signaling but decreased IFN pathways. In the KO cells, phosphorylated Akt and Erk1/2, two important RAS pathway effectors, were increased more than 3-fold, accompanied by increase of IGFBP3, MCAM, VIM, and CCND2 (cyclin D2) and decrease of RAC3 expression. High levels of lnc-FANCI-2 and lower levels of MCAM in cervical cancer patients are associated with improved survival. We found that lnc-FANCI-2 interacts specifically with 32 host proteins, including H13, HNRH1, K1H1, MAP4K4, and RNPS1, and knockdown of MAP4K4 in CaSki cells led to an increase of phosphorylation of Erk1/2 and somewhat Akt. In summary, a key function of lnc-FANCI-2 is to intrinsically regulate RAS signaling to impact cervical lesion progression and affect cervical cancer prognosis. SignificanceExpression of lnc-FANCI-2 is related to cervical lesion progression. Knock-out (KO) or knock-down (KD) of lnc-FANCI-2 expression in HPV16-positive cervical cancer cells CaSki significantly increases RAS signaling, phosphorylation of Akt and Erk1/2, and the epithelial mesenchymal transition factors. lnc-FANCI-2 KO also regulates the expression of a subset of cell soluble receptor proteins IGFBP3 and MCAM. A high level of lnc-FANCI-2 and lower level of MCAM in cervical cancer patients are associated with improved survival. lnc-FANCI-2 in CaSki cells interacts specifically with 32 host proteins, including MAP4K4. KD of MAP4K4 expression in CaSki cells led to an increase in phosphorylation of Erk1/2 and Akt. Thus, one lnc-FANCI-2 function is to intrinsically regulate RAS signaling to impact cervical lesion progression.

cancer biology↗

bioRxiv2023

Specificity and promiscuity of JAK recruitment regulates pleiotropy of cytokine-receptor signaling

Promiscuous binding of different Janus kinases (JAKs) to class I/II cytokine receptors has been reported, yet its role in signaling is unclear. To systematically explore JAK pairing in type I interferon (IFN-I) signaling, we generated an artificial IFN-I receptor (AIR) by replacing the extracellular domains of IFNAR1 and IFNAR2 with anti mEGFP and mCherry nanobodies. The heterodimeric AIR restored near-native IFN-I activity, while the homomeric variant of IFNAR2 (AIR-dR2) initiated much weaker signaling despite harboring docking sites for signal transducer and activator of transcription (STAT) proteins. AIR-dR1 was signaling inactive, yet, pulldown uncovered its ICD to bind both TYK2 and JAK1. To further investigate the roles of JAKs on the receptors, knockout (KO) JAK1, JAK2, TYK2, and JAK2/TYK2 were generated. JAK1 KO led to complete loss of IFN-I signaling, which was partially restored by TYK2 overexpression. TYK2 KO cells retained partial activity, which was elevated by JAK1 overexpression, suggesting both JAKs to partially substitute each other. Conversely, JAK2 KO only moderately impacted the biological activity of IFN-Is, even in JAK2/TYK2 KO cells. Live cell micropatterning confirmed promiscuous binding of JAK1, JAK2 and TYK2 to IFNAR1 and IFNAR2, in line with an AlphaFold model that shows JAKs interchangeability on IFNAR ICDs. Similar promiscuity of JAK binding was observed for TPOR and GHR but not EPOR, accompanied by different downstream signaling activity. The competitive binding of JAKs to cytokine receptors together with the highly diverse absolute and relative JAK expression levels can account for cell type-dependent signaling pleiotropy observed for cytokine receptors. One Sentence SummaryPromiscuous and interchangeable binding of JAKs to cytokine receptors enables cell type-specific pleiotropic signaling.

biochemistry↗

bioRxiv2023

Microbial community organization during anaerobic wastewater treatment

Amplicon sequencing data and operating data from anaerobic wastewater treatment plants from three Canadian pulp and paper mills were explored using correlation and network modularization approaches to study the microbial community organization and identify relationships between organisms and operating conditions. Each of the digesters contain two or three modules consisting of organisms that cover all trophic stages of anaerobic digestion. These modules are functioning independently from each other, and their relative abundance changes in response to varying operating conditions. The time delay between a change in digester operation and the change in the abundance of microorganisms was investigated using time-lagged operating parameters. This time delay ranged between two to four days and is likely influenced by the growth rates of the anaerobic microorganisms and the digester hydraulic retention time. Digester upsets due to plant shutdown periods and organic overload caused a drastic increase in the population of acetoclastic methanogens, acidogenic fermenters, and syntrophic acid degraders. As a response to impaired process conditions, the same Methanothrix amplicon sequence variant (ASV) dominated methanogenesis in the digesters of all three mills. The common characteristics of the organisms represented by this ASV should be further investigated for their role in alleviating the impact of digester upset conditions. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/553022v2_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@140e214org.highwire.dtl.DTLVardef@baa227org.highwire.dtl.DTLVardef@ebd2b8org.highwire.dtl.DTLVardef@573194_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2023

Differential functional coupling in Gp130-JAK complexes expands the plasticity of the interleukin-6 signaling axis

Cytokines dimerize/oligomerize surface receptors to activate signaling. While cytokine receptors preferentially bind only one member of the JAK family, ancestral cytokine receptors, such as Gp130, promiscuously recruit different JAKs to elicit their activities. Here, we have explored how the identity of JAKs in Gp130 signaling complexes can regulate functional outcomes. Using a synthetic biology approach, we show that Gp130 bound to different JAKs propagates distinct STAT activation profiles. While Gp130-JAK1 complexes activated both, STAT1 and STAT3 very potently, Gp130-JAK2 complexes exhibited a clear preference for STAT3 activation. Gp130-TYK2 complexes triggered overall weaker signaling but with diminished STAT specificity. The three JAKs competed for binding to Gp130 and led to differential activation of phospho-Tyr in the Gp130 intracellular domain. JAK1, JAK2 and to a lower extent TYK2 bound with comparable affinities to Gp130, and in response to IL-6 stimulation efficiently drove Gp130 dimerization. However, the three JAKs differentially affected Gp130 surface expression, identifying JAK-dependent receptor trafficking as a critical determinant of signaling plasticity. Our results provide new mechanistic insights into how differential functional coupling in Gp130-JAK complexes translates into unique signaling signatures that likely contribute to its large functional diversity.

cell biology↗

bioRxiv2023

Oncogenic Ras deregulates cell-substrate interactions during mitotic rounding and respreading to alter cell division orientation

Oncogenic Ras has been shown to change the way cancer cells divide by increasing the forces generated during mitotic rounding. In this way, RasV12 enables cancer cells to divide across a wider range of mechanical environments than normal cells. Here, we identify a further role for oncogenic Ras-ERK signalling in division by showing that RasV12 expression alters the shape, division orientation and respreading dynamics of cells as they exit mitosis, in a manner that depends on MEK and ERK. Many of these effects appear to result from the impact of RasV12 signalling on actomyosin contractility, since RasV12 induces the severing of retraction fibres that normally guide spindle positioning and provide a memory of the interphase cell shape. In support of this idea, the RasV12 phenotype is reversed by inhibition of actomyosin contractility, and can be mimicked by the loss of cell-substrate adhesion during mitosis. Thus, the induction of oncogenic Ras-ERK signalling leads to rapid changes in division orientation that, along with the effects of RasV12 on cell growth and cell cycle progression, are likely to disrupt epithelial tissue organisation and contribute to cancer dissemination.

cell biology↗

bioRxiv2021

Structural mechanism for bi-directional actin crosslinking by T-plastin

To fulfill the cytoskeletons diverse functions in cell mechanics and motility, actin networks with specialized architectures are built by crosslinking proteins, which bridge filaments to control micron-scale network geometry through nanoscale binding interactions via poorly defined structural mechanisms. Here, we introduce a machine-learning enabled cryo-EM pipeline for visualizing active crosslinkers, which we use to analyze human T-plastin, a member of the evolutionarily ancient plastin/fimbrin family of tandem calponin-homology domain (CHD) proteins. We define a sequential bundling mechanism which enables T-plastin to bridge filaments in both parallel and anti-parallel orientations. Our structural, biochemical, and cell biological data highlight inter-CHD linkers as key structural elements underlying flexible but stable crosslinking which are likely to be disrupted by mutations causing hereditary bone diseases. Beyond revealing how plastins are evolutionary optimized to crosslink dense actin networks with mixed polarity, our cryo-EM workflow will broadly enable analysis of the structural mechanisms underlying cytoskeletal network construction. One sentence summaryCryo-EM, biochemical, and cellular studies reveal how the crosslinking protein T-plastin bridges actin filaments in two opposing orientations.

biophysics↗

bioRxiv2021

Drug-free nasal spray as a barrier against SARS-CoV-2 infection: safety and efficacy in human nasal airway epithelia

BackgroundFor SARS-CoV-2 and other respiratory viruses, the nasal epithelium is a key portal for infection. Therefore, the nose is an important target of prophylactic and therapeutic interventions against these viruses. We developed a nasal spray (AM-301, a medical device marketed as Bentrio) to protect against infection by SARS-CoV-2 and potentially other viruses. Aims of the studyTo test the safety and efficacy of AM-301 against SARS-CoV-2 infection. MethodsAM-301 was tested on an in vitro 3D model of primary human nasal airway epithelium. Safety was assessed in assays for tight junction integrity, cytotoxicity and cilia beating frequency. Efficacy against SARS-CoV-2 infection was evaluated in prophylaxis and infection mitigation assays. ResultsAM-301 did not have any detrimental effect on the nasal epithelium. Prophylactic treatment with AM-301 reduced viral titer significantly vs. controls over 4 days, reaching a maximum reduction of 99%. When treatment with AM-301 was started 24 or 30 h after infection, epithelia that received the formulation had a 12- or 14-fold lower titer than controls. ConclusionAM-301 was found to be safe in vitro, and it significantly decelerated viral titer growth in experimental models of prophylaxis and mitigation. Its physical (non-pharmaceutical) mechanism of action, safety and efficacy pave the way for further investigation of its possible use against a broad spectrum of viruses, allergens and pollutants.

pharmacology and toxicology↗