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Rxivist combines preprints from bioRxiv with data from Twitter to help you find the papers being discussed in your field. Currently indexing 73,081 bioRxiv papers from 318,277 authors.

Most tweeted bioRxiv papers, last 7 days

732 results found. For more information, click each entry to expand.

61: BANDITS: Bayesian differential splicing accounting for sample-to-sample variability and mapping uncertainty
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Posted to bioRxiv 29 Aug 2019

BANDITS: Bayesian differential splicing accounting for sample-to-sample variability and mapping uncertainty
19 tweets bioinformatics

Simone Tiberi, Mark D. Robinson

Alternative splicing is a biological process during gene expression that allows a single gene to code for multiple proteins. However, splicing patterns can be altered in some conditions or diseases. Here, we present BANDITS, a R/Bioconductor package to perform differential splicing, at both gene and transcript-level, based on RNA-seq data. BANDITS uses a Bayesian hierarchical structure to explicitly model the variability between samples, and treats the transcript allocation of reads as latent variables. We perform an extensive benchmark across both simulated and experimental RNA-seq datasets, where BANDITS has extremely favorable performance with respect to the competitors considered.

62: Intracellular Lipid Droplet Accumulation Occurs Early Following Viral Infection and Is Required for an Efficient Interferon Response
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Posted to bioRxiv 13 Feb 2020

Intracellular Lipid Droplet Accumulation Occurs Early Following Viral Infection and Is Required for an Efficient Interferon Response
19 tweets microbiology

Ebony A. Monson, Keaton M. Crosse, Erika Duan, Weisan Chen, Ross D O'Shea, Linda M Wakem, Donna R. Whelan, Karla J. Helbig

Lipid droplets (LDs) are increasingly recognized as critical organelles in signalling events, transient protein sequestration and inter-organelle interactions. However, the role LDs play in antiviral innate immune pathways remains unknown. Here we demonstrate that induction of LDs occurs as early as 2 hours post viral infection, is transient, and returns to basal levels by 72 hours. This phenomenon occurred following viral infections, both in vitro and in vivo. Virally driven LD induction was type-I interferon (IFN) independent, however, was dependent on EGFR engagement, offering an alternate mechanism of LD induction in comparison to our traditional understanding of their biogenesis. Additionally, LD induction corresponded with enhanced cellular type-I and -III IFN production in infected cells, with enhanced LD accumulation decreasing viral replication of both HSV-1 and Zika virus (ZIKV). Here, we demonstrate for the first time, that LDs play vital roles in facilitating the magnitude of the early antiviral immune response specifically through the enhanced modulation of IFN following viral infection, and control of viral replication. By identifying LDs as a critical signalling organelle, this data represents a paradigm shift in our understanding of the molecular mechanisms which coordinate an effective antiviral response.

63: Common variation at the LRRK2 locus is associated with survival in the primary tauopathy progressive supranuclear palsy
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Posted to bioRxiv 04 Feb 2020

Common variation at the LRRK2 locus is associated with survival in the primary tauopathy progressive supranuclear palsy
18 tweets genetics

Edwin Jabbari, Manuela M.X. Tan, Regina H. Reynolds, Kin Y Mok, Raffaele Ferrari, David P. Murphy, Rebecca R. Valentino, Owen A. Ross, Dennis W. Dickson, Safa Al-Sarraj, Steve M. Gentleman, Kieren SJ Allinson, Zane Jaunmuktane, Janice L. Holton, Tamas Revesz, Thomas T. Warner, Andrew J. Lees, Mark R. Cookson, J. Raphael Gibbs, Jinhui Ding, Ruth Chia, Bryan J. Traynor, Sonja W. Scholz, Alexander Pantelyat, Coralie Viollet, Clifton L Dalgard, Olga Pletnikova, Juan C. Troncoso, Adam L. Boxer, Gesine Respondek, Günter U. Höglinger, David J Burn, Nicola Pavese, Alexander Gerhard, Christopher Kobylecki, P. Nigel Leigh, Alistair Church, Michele T.M. Hu, James B. Rowe, Mina Ryten, John Hardy, Maryam Shoai, Huw R Morris

The genetic basis of variation in the rate of disease progression of primary tauopathies has not been determined. In two independent progressive supranuclear palsy cohorts, we show that common variation at the LRRK2 locus determines survival from motor symptom onset to death, possibly through regulation of gene expression. This links together genetic risk in alpha-synuclein and tau disorders, and suggests that modulation of proteostasis and neuro-inflammation by LRRK2 inhibitors may have a therapeutic role across disorders.

64: The histone variant macroH2A1.1 regulates gene expression by direct association with their transcription start site.
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Posted to bioRxiv 29 Jan 2020

The histone variant macroH2A1.1 regulates gene expression by direct association with their transcription start site.
17 tweets genomics

Ludmila Recoules, Alexandre Heurteau, Flavien Raynal, Fatima Moutahir, Fabienne Bejjani, Isabelle Jariel-Encontre, Olivier Cuvier, Anne-Claire Lavigne, Kerstin Bystricky

The histone variant macroH2A1 (mH2A1) is involved in cellular growth, differentiation and reprogramming, but the underlying molecular mechanisms are a matter of debate. Different roles of mH2A1 in gene expression may relate to functional differences of its two splicing isoforms, mH2A1.1 and mH2A1.2. Here, we map for the first time genome-wide localization of endogenous mH2A1.1 and link the distribution of mH2A1.1 to control of gene expression in human breast cancer cells. In addition to localization shared with mH2A1.2 to facultative heterochromatin, mH2A1.1 specifically associates with regulatory elements required for gene activation, super-enhancers and promoters of highly expressed genes. Depending on the recruitment profile of mH2A1.1 to these elements, selective depletion of mH2A1.1 up- or downregulates its target genes. mH2A1.1 represses transcription when its binding is spread over the entire gene and promoter, and activates transcription when its binding is strictly confined to the transcription start site (TSS). Notably, RNA Polymerase II was frequently in pause at mH2A1.1-activated genes. Functionally, mH2A1.1-dependent regulation of a subset of paused genes impedes mammary tumor cell migration. Molecular mechanisms of mH2A1.1 function at the TSS uncovered by our study define an intriguing new mode of transcription regulation in cancer cells.

65: V. longisporum elicits media-dependent secretome responses with a further capacity to distinguish between plant-related environments
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Posted to bioRxiv 12 Feb 2020

V. longisporum elicits media-dependent secretome responses with a further capacity to distinguish between plant-related environments
17 tweets genetics

Miriam Leonard, Anika Kuehn, Rebekka Harting, Isabel Maurus, Alexandra Nagel, Jessica Starke, Harald Kusch, Oliver Valerius, Kirstin Feussner, Ivo H Feussner, Alexander Kaever, Manuel Landesfeind, Burkhard Morgenstern, Doerte Becher, Michael Hecker, Susanna A. Braus-Stromeyer, James W Kronstad, Gerhard H Braus

Verticillia cause a vascular wilt disease affecting a broad range of economically valuable crops. The fungus enters its host plants through the roots and colonizes the vascular system. It requires extracellular proteins for a successful plant colonization. The exoproteome of the allodiploid Verticillium longisporum was analyzed upon cultivation in different media. Secreted fungal proteins were identified by label free LC-MS/MS screening. V. longisporum induced two main secretion patterns. One response pattern was elicited in various non-plant related environments. The second pattern includes the exoprotein responses to the plant-related media, pectin-rich simulated xylem medium and pure xylem sap, which exhibited similar but additional distinct features. These exoproteomes include a shared core set of 223 secreted and similarly enriched fungal proteins. The pectin-rich medium significantly induced the secretion of 144 proteins including a number of pectin degrading enzymes, whereas xylem sap triggered a smaller but unique fungal exoproteome pattern with 32 enriched proteins. The latter pattern included proteins with domains of known effectors, metallopeptidases and carbohydrate-active enzymes. The most abundant and uniquely enriched proteins of these different groups are the necrosis and ethylene inducing-like proteins Nlp2 and Nlp3, the cerato-platanin proteins Cp1 and Cp2, the metallopeptidases Mep1 and Mep2 and the CAZys Gla1, Amy1 and Cbd1. Deletion of the majority of the corresponding genes caused no phenotypic changes during ex planta growth or invasion and colonization of tomato plants. However, we discovered that the NLP2 and NLP3 deletion strains were compromised in plant infections. Overall, our exoproteome approach revealed that the fungus induces specific secretion responses in different environments. The fungus has a general response to non-plant related media whereas it is able to fine-tune its exoproteome in the presence of plant material. Importantly, the xylem sap-specific exoproteome pinpointed Nlp2 and Nlp3 as single effectors required for successful V. dahliae colonization.

66: Benchmarking DNA Methylation Assays for Marine Invertebrates
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Posted to bioRxiv 12 Feb 2020

Benchmarking DNA Methylation Assays for Marine Invertebrates
17 tweets ecology

Groves Dixon, Mikhail V. Matz

Interrogation of chromatin modifications, such as DNA methylation, has potential to improve forecasting and conservation of marine ecosystems. The standard method for assaying DNA methylation (Whole Genome Bisulfite Sequencing), however, is too costly to apply at the scales required for ecological research. Here we evaluate different methods for measuring DNA methylation for ecological epigenetics. We compare Whole Genome Bisulfite Sequencing (WGBS) with Methylated CpG Binding Domain Sequencing (MBD-seq), and a modified version of MethylRAD we term methylation-dependent Restriction site-Associated DNA sequencing (mdRAD). We evaluate these three assays in measuring variation in methylation across the genome, between genotypes, and between polyp types in the reef-building coral Acropora millepora. We find that all three assays measure absolute methylation levels similarly, with tight correlations for methylation of gene bodies (gbM), as well as exons and 1Kb windows. Correlations for differential gbM between genotypes were weaker, but still concurrent across assays. We detected little to no reproducible differences in gbM between polyp types. We conclude that MBD-seq and mdRAD are reliable cost-effective alternatives to WGBS. Moreover, the considerably lower sequencing effort required for mdRAD to produce comparable methylation estimates makes it particularly useful for ecological epigenetics.

67: Visual and semantic representations predict subsequent memory in perceptual and conceptual memory tests
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Posted to bioRxiv 12 Feb 2020

Visual and semantic representations predict subsequent memory in perceptual and conceptual memory tests
17 tweets neuroscience

Simon W. Davis, Benjamin Geib, Erik Wing, Wei-Chun Wang, Mariam Hovhannisyan, Zachary Monge, Roberto Cabeza

It is generally assumed that the encoding of a single event generates multiple memory representations, which contribute differently to subsequent episodic memory. We used fMRI and representational similarity analysis (RSA) to examine how visual and semantic representations predicted subsequent memory for single item encoding (e.g., seeing an orange). Three levels of visual representations corresponding to early, middle, and late visual processing stages were based on a deep neural network. Three levels of semantic representations were based on normative Observed ("is round"), Taxonomic ("is a fruit"), and Encyclopedic features ("is sweet"). We identified brain regions where each representation type predicted later Perceptual Memory, Conceptual Memory, or both (General Memory). Participants encoded objects during fMRI, and then completed both a word-based conceptual and picture-based perceptual memory test. Visual representations predicted subsequent Perceptual Memory in visual cortices, but also facilitated Conceptual and General Memory in more anterior regions. Semantic representations, in turn, predicted Perceptual Memory in visual cortex, Conceptual Memory in the perirhinal and inferior prefrontal cortex, and General Memory in the angular gyrus. These results suggest that the contribution of visual and semantic representations to subsequent memory effects depends on a complex interaction between representation, test type, and storage location.

68: Cadherin clustering controls heterogeneous, asymmetric junction dynamics during vertebrate axis elongation
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Posted to bioRxiv 12 Feb 2020

Cadherin clustering controls heterogeneous, asymmetric junction dynamics during vertebrate axis elongation
17 tweets cell biology

Robert Huebner, Abdul N. Malmi-Kakkada, Sena Sarikaya, Shinuo Weng, D. Thirumalai, John B. Wallingford

Tissue morphogenesis requires the control of physical forces by molecular patterning systems encoded in the genome. For example, tissue-level mechanical transformations in vertebrate embryos require the activity of cadherin adhesion proteins and the Planar Cell Polarity (PCP) signaling system. At the tissue level, collective cell movements are known to be highly complex, displaying combinations of fluid/solid behaviors, jamming transitions, and glass-like dynamics. The sub-cellular origin of these heterogeneous tissue dynamics is undefined. Here, high-speed super-resolution imaging and physical methods for quantifying motion revealed that the sub-cellular behaviors underlying vertebrate embryonic axis elongation display glass-like dynamic heterogeneities. A combination of theory and experiment demonstrates these behaviors are highly local, displaying asymmetries even within individual cell-cell junctions. Moreover, we demonstrate that these mechanical asymmetries require patterned lateral (cis-) clustering of cadherins that is dependent upon PCP signaling. These findings illuminate the mechanisms by which defined molecular patterning systems tune the mechanics of sub-cellular behaviors that drive vertebrate axis elongation.

69: Explosive sensing with insect-based biorobots
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Posted to bioRxiv 11 Feb 2020

Explosive sensing with insect-based biorobots
17 tweets bioengineering

Debajit Saha, Darshit Mehta, Ege Altan, Rishabh Chandak, Mike Traner, Ray Lo, Prashant Gupta, Srikanth Singamaneni, Shantanu Chakrabartty, Baranidharan Raman

Stand-off chemical sensing is an important capability with applications in several domains including homeland security. Engineered devices for this task, popularly referred to as electronic noses, have limited capacity compared to the broad-spectrum abilities of the biological olfactory system. Therefore, we propose a hybrid bio-electronic solution that directly takes advantage of the rich repertoire of olfactory sensors and sophisticated neural computational framework available in an insect olfactory system. We show that select subsets of neurons in the locust (Schistocerca americana) brain were activated upon exposure to various explosive chemical species (such as DNT and TNT). Responses from an ensemble of neurons provided a unique, multivariate fingerprint that allowed discrimination of explosive vapors from non-explosive chemical species and from each other. Notably, target chemical recognition could be achieved within a few hundred milliseconds of exposure. Finally, we developed a minimally-invasive surgical approach and mobile multi-unit electrophysiological recording system to tap into the neural signals in a locust brain and realize a biorobotic explosive sensing system. In sum, our study provides the first demonstration of how biological olfactory systems (sensors and computations) can be hijacked to develop a cyborg chemical sensing approach.

70: Adapting CRISPR/Cas9 System for Targeting Mitochondrial Genome
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Posted to bioRxiv 12 Feb 2020

Adapting CRISPR/Cas9 System for Targeting Mitochondrial Genome
17 tweets molecular biology

Syed-Rehan A Hussain, Mehmet E. Yalvac, Bendict Khoo, Sigrid Eckardt, K John McLaughlin

Gene editing of the mitochondrial genome using CRISPR-Cas9 system is highly challenging mainly due to sub-efficient delivery of guide RNA and Cas9 enzyme complexes into mitochondria. In this study, we were able to perform gene editing in the mitochondrial DNA by appending NADH-ubiquinone oxidoreductase chain 4 (ND4) targeting guide RNA to a RNA transport derived stem loop element (RP-loop) and expressing the Cas9 enzyme with preceding mitochondrial localization sequence. Our results showed mitochondrial co-localization of RP-loop gRNA and a marked reduction of ND4 expression in the cells carrying a A11204G variant in their ND4 sequence coincidently decreasing the mtDNA levels. This proof-of-concept study suggests that stem loop element added sgRNA can be transported to the mitochondria and functionally interact with Cas9 to mediate sequence specific mtDNA cleavage. Using this novel approach to target the mtDNA, our results provide further evidence that CRISPR-Cas9 mediated gene editing might potentially be used to treat mtDNA related diseases.

71: Competitive binding of independent extension and retraction motors explains the quantitative dynamics of type IV pili
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Posted to bioRxiv 13 Feb 2020

Competitive binding of independent extension and retraction motors explains the quantitative dynamics of type IV pili
16 tweets microbiology

Matthias D. Koch, Chenyi Fei, Ned S Wingreen, Joshua W Shaevitz, Zemer Gitai

The functions of type IV pili (TFP) are mediated by cycles of extension and retraction. The coordination of these cycles remains mysterious due to poor quantification of TFP dynamics. Here we fluorescently label the TFP in the opportunistic pathogen Pseudomonas aeruginosa and track the full extension and retraction cycles of individual TFP to quantify their dynamics. We test several models for the switch between extension and retraction using quantitative experiments, biophysical modeling and genetics. We invalidate the prominent hypothesis that this switch is triggered by surface contact. Instead, we show that the entire repetitive cycle of extension and retraction of individual TFP is governed by the stochastic binding of antagonistic extension and retraction motors and explain how this mechanism quantitatively defines physiologically-important features like TFP length and their production rate. Interestingly, our results suggest that the major throttle of TFP production is the unbinding of the retraction motor.

72: CRISPR-Cas12a exploits R-loop asymmetry to form double strand breaks
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Posted to bioRxiv 10 Feb 2020

CRISPR-Cas12a exploits R-loop asymmetry to form double strand breaks
16 tweets biochemistry

Joshua C. Cofsky, Deepti Karandur, Carolyn J. Huang, Isaac P. Witte, John Kuriyan, Jennifer A. Doudna

Most type V CRISPR-Cas interference proteins use a single RuvC active site to make RNA-guided breaks in double-stranded DNA substrates, an activity essential for both bacterial immunity and genome editing applications. The best-studied of these enzymes, Cas12a, initiates DNA cutting by forming a 20-nucleotide R-loop in which the guide RNA displaces one of the DNA strands of a double-helical substrate, positioning the DNase active site for first-strand cleavage. However, crystal structures and biochemical data have not explained how the second strand is cut to complete the double-strand break. Here, we show that Cas12a-mediated R-loop formation destabilizes DNA at the second-strand cleavage site, which is located outside of the R-loop structure and beyond the 3' end of the guide RNA. Chemical and fluorescent DNA probes reveal that this destabilization is an intrinsic feature of DNA flanking the RNA-3' side of R-loops and does not require direct protein interactions. Interestingly, DNA flanking the RNA-5' side of R-loops is not intrinsically unstable. This asymmetry in R-loop structure may explain the uniformity of guide RNA architecture and the single-active-site cleavage mechanism that are fundamental features of all type V CRISPR-Cas systems.

73: Covert spatial attention speeds target individuation
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Posted to bioRxiv 12 Nov 2019

Covert spatial attention speeds target individuation
16 tweets neuroscience

Joshua J. Foster, Emma M Bsales, Edward Awh

Covert spatial attention has long been thought to speed visual processing. Psychophysics studies have shown that target information accrues faster at attended locations than at unattended locations. However, with behavioral evidence alone, it is difficult to determine whether attention speeds visual processing of the target, or subsequent post-perceptual stages of processing (e.g. decision making and response selection). Moreover, while many studies have shown that that attention can boost the amplitude of visually-evoked neural responses, no effect has been observed on the latency of those neural responses. Here, we offer new evidence that may reconcile the neural and behavioral findings. Our study focused on the N2pc, an EEG marker of visual selection that has been linked with object individuation - the formation of an object representation that is distinct from the background and from other objects. In two experiments, we manipulated whether or not covert attention was precisely deployed to the location of an impending search target. We found that the target-evoked N2pc onset approximately 20 ms earlier when the target location was cued than when it was not cued. Thus, although attention may not speed the earliest stages of sensory processing, attention does speed the critical transition between raw sensory encoding and the formation of individuated object representations.

74: A Casz1 - NuRD complex regulates temporal identity transitions in neural progenitors
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Posted to bioRxiv 12 Feb 2020

A Casz1 - NuRD complex regulates temporal identity transitions in neural progenitors
16 tweets developmental biology

Pierre Mattar, Christine Jolicoeur, Sujay Shah, Michel Cayouette

Neural progenitor cells alter their output over developmental time to generate different types of neurons and glia in the correct sequences and proportions. A number of "temporal identity factors" that control transitions in progenitor competence have been identified, but the molecular mechanisms underlying their function remain unclear. Here, we asked how the transcription factor Casz1, the mammalian orthologue of Drosophila castor, regulates competence during retinal neurogenesis. We show that Casz1 is required to control the transition between neurogenesis and gliogenesis. Using BioID proteomics, we reveal that Casz1 interacts with the nucleosome remodeling and deacetylase (NuRD) complex in retinal cells. Finally, we show that both the NuRD and the polycomb repressor complexes are required for Casz1 to promote the rod fate and suppress gliogenesis. As other temporal identity factors have been found to interact with the NuRD complex in other contexts, we propose that these factors might act through a common biochemical process to regulate neurogenesis.

75: RootDigger: a root placement program for phylogenetic trees
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Posted to bioRxiv 14 Feb 2020

RootDigger: a root placement program for phylogenetic trees
16 tweets bioinformatics
76: Differential submergence tolerance between juvenile and adult Arabidopsis plants involves the ANAC017 transcription factor
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Posted to bioRxiv 13 Feb 2020

Differential submergence tolerance between juvenile and adult Arabidopsis plants involves the ANAC017 transcription factor
16 tweets plant biology

Liem T. Bui, Vinay Shukla, Federico Manuel Giorgi, Alice Trivellini, Pierdomenico Perata, Francesco Licausi, Beatrice Giuntoli

Plants need to attune stress responses to the ongoing developmental programs to maximize their efficacy. For instance, successful submergence adaptation is often associated to a delicate poise between saving resources and their expenditure to activate measures that allow stress avoidance or attenuation. We observed a significant decrease in submergence tolerance associated with aging in Arabidopsis thaliana, with a critical step between two and three weeks of post-germination development. This sensitization to flooding was concomitant with the transition from juvenility to adulthood. Transcriptomic analyses indicated that a group of genes related to ABA and oxidative stress response was more expressed in juvenile plants than in adult ones. These genes are induced by endomembrane tethered ANAC factors that were in turn activated by submergence-associated oxidative stress. A combination of molecular, biochemical and genetic analyses showed that these genes are located in genomic regions that move towards a heterochromatic state with adulthood, as marked by lysine 4 dimethylation of histone H3. We concluded that, while the mechanism of flooding stress perception and signal transduction were unaltered between juvenile and adult phases, the sensitivity that these mechanisms set into action is integrated, via epigenetic regulation, into the developmental programme of the plant.

77: The LUBAC participates in Lysophosphatidic Acid-induced NF-κB Activation
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Posted to bioRxiv 13 Feb 2020

The LUBAC participates in Lysophosphatidic Acid-induced NF-κB Activation
16 tweets immunology

Tiphaine Douanne, Sarah Chapelier, Robert Rottapel, Julie Gavard, Nicolas Bidère

The natural bioactive glycerophospholipid lysophosphatidic acid (LPA) binds to its cognate G protein-coupled receptors (GPCRs) on the cell surface to promote the activation of several transcription factors, including NF-κB. LPA-mediated activation of NF-κB relies on the formation of a signalosome that contains the scaffold CARMA3, the adaptor BCL10 and the paracaspase MALT1 (CBM complex). The CBM has been extensively studied in lymphocytes, where it links antigen receptors to NF-κB activation via the recruitment of the linear ubiquitin assembly complex (LUBAC), a tripartite complex of HOIP, HOIL1 and SHARPIN. Moreover, MALT1 cleaves the LUBAC subunit HOIL1 to further enhance NF-κB activation. However, the contribution of the LUBAC downstream of GPCRs has not been investigated. By using murine embryonic fibroblasts from mice deficient for HOIP, HOIL1 and SHARPIN, we report that the LUBAC is crucial for the activation of NF-κB in response to LPA. Further echoing the situation in lymphocytes, LPA unbridles the protease activity of MALT1, which cleaves HOIL1 at the Arginine 165. The expression of a MALT1-insensitive version of HOIL1 reveals that this processing is required for the optimal production of the NF-κB target cytokine interleukin-6. Lastly, we provide evidence that the guanine exchange factor GEF-H1 activated by LPA favors MALT1-mediated cleavage of HOIL1 and NF-κB signaling. Together, our results unveil a critical role for the LUBAC as a positive regulator of NF-κB signaling downstream of GPCRs.

78: Potentially highly potent drugs for 2019-nCoV
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Posted to bioRxiv 13 Feb 2020

Potentially highly potent drugs for 2019-nCoV
16 tweets bioinformatics

Duc Nguyen, Kaifu Gao, Jiahui Chen, Rui Wang, Guewei Wei

The World Health Organization (WHO) has declared 2019 novel coronavirus (2019-nCoV) infection outbreak a global health emergency. Currently, there is no effective anti-2019-nCoV medication. The sequence identity of the 3CL proteases of 2019-nCoV and SARS is 96%, which provides a sound foundation for structural-based drug repositioning (SBDR). Based on a SARS 3CL protease X-ray crystal structure, we construct a 3D homology structure of 2019-nCoV 3CL protease. Based on this structure and existing experimental datasets for SARS 3CL protease inhibitors, we develop an SBDR model using deep learning and mathematics to screen 1465 drugs in the DrugBank that have been approved by the U.S. Food and Drug Administration (FDA). We found that a number of FDA approved drugs are potentially highly potent to 2019-nCoV.

79: Emergence of stealth polymorphs that escape α-synuclein amyloid monitoring, take over and acutely spread in neurons
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Posted to bioRxiv 12 Feb 2020

Emergence of stealth polymorphs that escape α-synuclein amyloid monitoring, take over and acutely spread in neurons
16 tweets neuroscience

Francesca De Giorgi, Florent Laferriere, Federica Zinghirino, Emilie Faggiani, Alons Lends, Mathilde Bertoni, Xuan Yu, Axelle Grelard, Estelle Morvan, Birgit Habenstein, Nathalie Dutheil, Evelyne Doudnikoff, Jonathan Daniel, Stephane Claverol, Chuan Qin, Antoine Loquet, Erwan Bezard, Francois Ichas

The conformational strain diversity characterizing α-synuclein (α-syn) amyloid fibrils is possibly at the origin of the different clinical presentations of synucleinopathies. Experimentally, various α-syn fibril polymorphs have been obtained from distinct fibrillization conditions by altering the medium constituents and were selected by amyloid monitoring using the probe Thioflavin T (ThT). We report here that besides classical ThT positive products, fibrillization in saline simultaneously gives rise to competing fibril polymorphs that are invisible to ThT (stealth polymorphs), and that can take over. Due to competition, spontaneous generation of such stealth polymorphs bears on the apparent fibrillization kinetics and on the final plateau values. Their emergence has thus been ignored so far or mistaken for fibrillization inhibitions/failures. Compared to their ThT-positive counterparts, and as judged from their chemical shift resonances fingerprint, these new stealth polymorphs present a yet undescribed atomic organization and show an exacerbated propensity (approx. 20-fold) towards self-replication in cortical neurons. They also trigger a long distance synucleinopathic spread along nigro-striatal projections in vivo. In order to rapidly screen fibrillization products for the presence of such stealth polymorphs, we designed a simple multiplexed assay that can be easily and rapidly operated. This assay allows us to demonstrate the sustainability of the conformational replication of these novel and particularly invasive strains. It should also be of help to avoid erroneous upstream interpretations of fibrillization rates based on sole ThT, and to expedite further structural and functional characterization of stealth amyloid assemblies.

80: The genome sequence of the Jean-Talon strain, an archeological tetraploid beer yeast from Québec
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Posted to bioRxiv 12 Feb 2020

The genome sequence of the Jean-Talon strain, an archeological tetraploid beer yeast from Québec
15 tweets genomics

Anna Fijarczyk, Mathieu Hénault, Souhir Marsit, Guillaume Charron, Tobias Fischborn, Luc Nicole-Labrie, Christian R Landry

The genome sequences of archeological yeast isolates can reveal insights about the history of human baking, brewing and winemaking activities and migration around the globe. A yeast strain called Jean-Talon was recently isolated from the vaults of the Intendant's Palace of Nouvelle France on a historical site in Québec City. This site has been occupied by various breweries, starting from the end of the 17th century and until the middle of the 20th century. We sequenced the genome of the Jean-Talon strain with short and long reads and reanalyzed the genomes of hundreds of yeast strains to identify its species of origin and determine how it relates to other domesticated and wild strains. The Jean-Talon strain is a tetraploid strain with numerous aneuploidies, is partially sterile and most closely related to beer strains from the beer and bakery genetic groups and industrial strains from the United Kingdom and Belgium. We conclude from this that the Jean-Talon strain most likely derives from recent brewing activities that took place in the same location and not from wild yeast that could have been domesticated by the original brewers of the Nouvelle France on the site.

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