Cell-based HTS identifies a chemical chaperone for preventing ER protein aggregation and proteotoxicity
The endoplasmic reticulum (ER) is responsible for folding secretory and membrane proteins, but disturbed ER proteostasis may lead to protein aggregation and subsequent cellular and clinical pathologies. Chemical chaperones have recently emerged as a potential therapeutic approach for ER stress-related diseases. Here, we identified 2-phenylimidazo[2,1-b]benzothiazole derivatives (IBTs) as chemical chaperones in a cell-based high-throughput screen. Biochemical and chemical biology approaches revealed that IBT21 directly binds to unfolded or misfolded proteins and inhibits protein aggregation. Finally, IBT21 prevented cell de...
Source: eLife - December 17, 2019 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

Invariant representations of mass in the human brain
An intuitive understanding of physical objects and events is critical for successfully interacting with the world. Does the brain achieve this understanding by running simulations in a mental physics engine, which represents variables such as force and mass, or by analyzing patterns of motion without encoding underlying physical quantities? To investigate, we scanned participants with fMRI while they viewed videos of objects interacting in scenarios indicating their mass. Decoding analyses in brain regions previously implicated in intuitive physical inference revealed mass representations that generalized across variations...
Source: eLife - December 17, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Single-cell modeling of routine clinical blood tests reveals transient dynamics of human response to blood loss
We present an approach for modeling the unsteady-state population dynamics of the human response to controlled blood loss using these clinical measurements of single-red blood cell (RBC) volume and hemoglobin. We find that the response entails (1) increased production of new RBCs earlier than is currently detectable clinically and (2) a previously unrecognized decreased RBC turnover. Both component responses offset the loss of blood. The model provides a personalized dimensionless ratio that quantifies the balance between increased production and delayed clearance for each individual and may enable earlier detection of bot...
Source: eLife - December 17, 2019 Category: Biomedical Science Tags: Computational and Systems Biology Human Biology and Medicine Source Type: research

Navigating the garden of forking paths for data exclusions in fear conditioning research
In this report, we illustrate the considerable impact of researcher degrees of freedom with respect to exclusion of participants in paradimgs with a learning element. We illustrate this empirically through case examples from human fear conditioning research where the exclusion of 'non-learners' and 'non-responders' is common - despite a lack of consensus on how to define these groups. We illustrate the substantial heterogeneity in exclusion criteria based on a systematic literature search and highlight potential problems and pitfalls of different definitions through case examples based on re-analyses of existing data sets....
Source: eLife - December 16, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

PCK1 and DHODH drive colorectal cancer liver metastatic colonization and hypoxic growth by promoting nucleotide synthesis
Colorectal cancer (CRC) is a major cause of human death. Mortality is primarily due to metastatic organ colonization, with the liver being the primary organ affected. We modeled metastatic CRC (mCRC) liver colonization using patient-derived primary and metastatic tumor xenografts (PDX). Such PDX modeling predicted patient survival outcomes.In vivo selection of multiple PDXs for enhanced metastatic colonization capacity upregulated the gluconeogenic enzyme PCK1, which enhanced liver metastatic hypoxic growth by driving pyrimidine nucleotide biosynthesis under hypoxia. Consistently, highly metastatic tumors upregulated multi...
Source: eLife - December 16, 2019 Category: Biomedical Science Tags: Cancer Biology Human Biology and Medicine Source Type: research

Opioids modulate an emergent rhythmogenic process to depress breathing
How mammalian neural circuits generate rhythmic activity in motor behaviors, such as breathing, walking, and chewing, remains elusive. For breathing, rhythm generation is localized to a brainstem nucleus, the preB ötzinger Complex (preBötC). Rhythmic preBötC population activity consists of strong inspiratory bursts, which drive motoneuronal activity, and weaker burstlets, which we hypothesize reflects an emergent rhythmogenic process. If burstlets underlie inspiratory rhythmogenesis, respiratory depressant s, such as opioids, should reduce burstlet frequency. Indeed, in medullary slices from neonatal mice, t...
Source: eLife - December 16, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Tritrophic metabolism of plant chemical defenses and its effects on herbivore and predator performance
Insect herbivores are frequently reported to metabolize plant defense compounds, but the physiological and ecological consequences are not fully understood. It has rarely been studied whether such metabolism is genuinely beneficial to the insect, and whether there are any effects on higher trophic levels. Here, we manipulated the detoxification of plant defenses in the herbivorous pest diamondback moth (Plutella xylostella) to evaluate changes in fitness, and additionally examined the effects on a predatory lacewing (Chrysoperla carnea). Silencing glucosinolate sulfatase genes resulted in the systemic accumulation of toxic...
Source: eLife - December 16, 2019 Category: Biomedical Science Tags: Ecology Source Type: research

Ribosome biogenesis restricts innate immune responses to virus infection and DNA
Ribosomes are universally important in biology and their production is dysregulated by developmental disorders, cancer, and virus infection. Although presumed required for protein synthesis, how ribosome biogenesis impacts virus reproduction and cell-intrinsic immune responses remains untested. Surprisingly, we find that restricting ribosome biogenesis stimulated human cytomegalovirus (HCMV) replication without suppressing translation. Interfering with ribosomal RNA (rRNA) accumulation triggered nucleolar stress and repressed expression of 1,392 genes, including High Mobility Group Box 2 (HMGB2), a chromatin-associated pro...
Source: eLife - December 16, 2019 Category: Biomedical Science Tags: Immunology and Inflammation Source Type: research

Tissue-specific shaping of the TCR repertoire and antigen specificity of iNKT cells
Tissue homeostasis is critically dependent on the function of tissue-resident lymphocytes, including lipid-reactive invariant natural killer T (iNKT) cells. Yet, if and how the tissue environment shapes the antigen specificity of iNKT cells remains unknown. By analysing iNKT cells from lymphoid tissues of mice and humans we demonstrate that their T cell receptor (TCR) repertoire is highly diverse and is distinct for cells from various tissues resulting in differential lipid-antigen recognition. Within peripheral tissues iNKT cell recent thymic emigrants exhibit a different TCR repertoire than mature cells, suggesting that ...
Source: eLife - December 16, 2019 Category: Biomedical Science Tags: Immunology and Inflammation Source Type: research

< i > E. coli < /i > TraR allosterically regulates transcription initiation by altering RNA polymerase conformation
TraR and its homolog DksA are bacterial proteins that regulate transcription initiation by binding directly to RNA polymerase (RNAP) rather than to promoter DNA. Effects of TraR mimic the combined effects of DksA and its cofactor ppGpp, but the structural basis for regulation by these factors remains unclear. Here, we use cryo-electron microscopy to determine structures ofEscherichia coli RNAP, with or without TraR, and of an RNAP-promoter complex. TraR binding induced RNAP conformational changes not seen in previous crystallographic analyses, and a quantitative analysis revealed TraR-induced changes in RNAP conformational...
Source: eLife - December 16, 2019 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Structural Biology and Molecular Biophysics Source Type: research

Axon-like protrusions promote small cell lung cancer migration and metastasis
Metastasis is the main cause of death in cancer patients but remains a poorly understood process. Small cell lung cancer (SCLC) is one of the most lethal and most metastatic cancer types. SCLC cells normally express neuroendocrine and neuronal gene programs but accumulating evidence indicates that these cancer cells become relatively more neuronal and less neuroendocrine as they gain the ability to metastasize. Here we show that mouse and human SCLC cells in culture andin vivo can grow cellular protrusions that resemble axons. The formation of these protrusions is controlled by multiple neuronal factors implicated in axono...
Source: eLife - December 13, 2019 Category: Biomedical Science Tags: Cancer Biology Cell Biology Source Type: research

Telophase correction refines division orientation in stratified epithelia
During organogenesis, precise control of spindle orientation balances proliferation and differentiation. In the developing murine epidermis, planar and perpendicular divisions yield symmetric and asymmetric fate outcomes, respectively. Classically, division axis specification involves centrosome migration and spindle rotation, events occurring early in mitosis. Here, we identify a novel orientation mechanism which corrects erroneous anaphase orientations during telophase. The directionality of reorientation correlates with the maintenance or loss of basal contact by the apical daughter. While the scaffolding protein LGN is...
Source: eLife - December 13, 2019 Category: Biomedical Science Tags: Cell Biology Developmental Biology Source Type: research

Uncovering the secret life of Rho GTPases
New methods to directly visualize Rho GTPases reveal how a protein called RhoGDI regulates the activity of these 'molecular switches' at the plasma membrane. (Source: eLife)
Source: eLife - December 13, 2019 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

Direct comparison of clathrin-mediated endocytosis in budding and fission yeast reveals conserved and evolvable features
Conserved proteins drive clathrin-mediated endocytosis (CME), which from yeast to humans involves a burst of actin assembly. To gain mechanistic insights into this process, we performed a side-by-side quantitative comparison of CME in two distantly related yeast species. Though endocytic protein abundance inS. pombe andS. cerevisiae is more similar than previously thought, membrane invagination speed and depth are two-fold greater in fission yeast. In both yeasts, accumulation of ~70 WASp molecules activates the Arp2/3 complex to drive membrane invagination. In contrast to budding yeast, WASp-mediated actin nucleation play...
Source: eLife - December 12, 2019 Category: Biomedical Science Tags: Cell Biology Source Type: research

Single cell transcriptional signatures of the human placenta in term and preterm parturition
More than 135 million births occur each year; yet, the molecular underpinnings of human parturition in gestational tissues, and in particular the placenta, are still poorly understood. The placenta is a complex heterogeneous organ including cells of both maternal and fetal origin, and insults that disrupt the maternal-fetal dialogue could result in adverse pregnancy outcomes such as preterm birth. There is limited knowledge of the cell type composition and transcriptional activity of the placenta and its compartments during physiologic and pathologic parturition. To fill this knowledge gap, we used scRNA-seq to profile the...
Source: eLife - December 12, 2019 Category: Biomedical Science Tags: Genetics and Genomics Human Biology and Medicine Source Type: research

Essential role for InSyn1 in dystroglycan complex integrity and cognitive behaviors in mice
Human mutations in the dystroglycan complex (DGC) result in not only muscular dystrophy but also cognitive impairments. However, the molecular architecture critical for the synaptic organization of the DGC in neurons remains elusive. Here we report Inhibitory Synaptic protein 1 (InSyn1) is a critical component of the DGC whose loss alters the composition of the GABAergic synapses, excitatory/inhibitory balancein vitro andin vivo, and cognitive behavior. Association of InSyn1 with DGC subunits is required for InSyn1 synaptic localization. InSyn1 null neurons also show a significant reduction in DGC and GABA receptor distrib...
Source: eLife - December 12, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Magnetic resonance measurements of cellular and sub-cellular membrane structures in live and fixed neural tissue
We develop magnetic resonance (MR) methods for real-time measurement of tissue microstructure and membrane permeability of live and fixed excised neonatal mouse spinal cords. Diffusion and exchange MR measurements are performed using the strong static gradient produced by a single-sided permanent magnet. Using tissue delipidation methods, we show that water diffusion is restricted solely by lipid membranes. Most of the diffusion signal can be assigned to water in tissue which is far from membranes. The remaining 25% can be assigned to water restricted on length scales of roughly a micron or less, near or within membrane st...
Source: eLife - December 12, 2019 Category: Biomedical Science Tags: Cell Biology Source Type: research

Developmentally regulated < i > Tcf7l2 < /i > splice variants mediate transcriptional repressor functions during eye formation
Tcf7l2 mediates Wnt/ β-Catenin signalling during development and is implicated in cancer and type-2 diabetes. The mechanisms by which Tcf7l2 and Wnt/β-Catenin signalling elicit such a diversity of biological outcomes are poorly understood. Here, we study the function of zebrafishtcf7l2alternative splice variants and show that only variants that include exon five or an analogous humantcf7l2 variant can effectively provide compensatory repressor function to restore eye formation in embryos lackingtcf7l1a/tcf7l1b function. Knockdown of exon five specifictcf7l2 variants intcf7l1a mutants also compromises eye formatio...
Source: eLife - December 12, 2019 Category: Biomedical Science Tags: Developmental Biology Source Type: research

< i > Straightjacket/ α2δ3 < /i > deregulation is associated with cardiac conduction defects in myotonic dystrophy type 1
Cardiac conduction defects decrease life expectancy in myotonic dystrophy type 1 (DM1), a CTG repeat disorder involving misbalance between two RNA binding factors, MBNL1 and CELF1. However, how DM1 condition translates into conduction disorders remains poorly understood. Here we simulated MBNL1 and CELF1 misbalance in theDrosophila heart and performed TU-tagging-based RNAseq of cardiac cells. We detected deregulations of several genes controlling cellular calcium levels, including increased expression of straightjacket/ α2δ3, which encodes a regulatory subunit of a voltage-gated calcium channel. Straightjacket ...
Source: eLife - December 12, 2019 Category: Biomedical Science Tags: Human Biology and Medicine Source Type: research

The computation of directional selectivity in the < i > Drosophila < /i > OFF motion pathway
In flies, the direction of moving ON and OFF features is computed separately. T4 (ON) and T5 (OFF) are the first neurons in their respective pathways to extract a directionally selective response from their non-selective inputs. Our recent study of T4 found that the integration of offset depolarizing and hyperpolarizing inputs is critical for the generation of directional selectivity. However, T5s lack small-field inhibitory inputs, suggesting they may use a different mechanism. Here we used whole-cell recordings of T5 neurons and found a similar receptive field structure: fast depolarization and persistent, spatially offs...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

The recovery of standing and locomotion after spinal cord injury does not require task-specific training
After complete spinal cord injury, mammals, including mice, rats and cats, recover hindlimb locomotion with treadmill training. The premise is that sensory cues consistent with locomotion reorganize spinal sensorimotor circuits. Here, we show that hindlimb standing and locomotion recover after spinal transection in cats without task-specific training. Spinal-transected cats recovered full weight bearing standing and locomotion after five weeks of rhythmic manual stimulation of triceps surae muscles (non-specific training) and without any intervention. Moreover, cats modulated locomotor speed and performed split-belt locomo...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Axon TRAP reveals learning-associated alterations in cortical axonal mRNAs in the lateral amgydala
Local translation can support memory consolidation by supplying new proteins to synapses undergoing plasticity. Translation in adult forebrain dendrites is an established mechanism of synaptic plasticity and is regulated by learning, yet there is no evidence for learning-regulated protein synthesis in adult forebrain axons, which have traditionally been believed to be incapable of translation. Here we show that axons in the adult rat amygdala contain translation machinery, and use translating ribosome affinity purification (TRAP) with RNASeq to identify mRNAs in cortical axons projecting to the amygdala, over 1200 of which...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Rod nuclear architecture determines contrast transmission of the retina and behavioral sensitivity in mice
Rod photoreceptors of nocturnal mammals display a striking inversion of nuclear architecture, which has been proposed as an evolutionary adaptation to dark environments. However, the nature of visual benefits and the underlying mechanisms remains unclear. It is widely assumed that improvements in nocturnal vision would depend on maximization of photon capture at the expense of image detail. Here we show that retinal optical quality improves 2-fold during terminal development, and that this enhancement is caused by nuclear inversion. We further demonstrate that improved retinal contrast transmission, rather than photon-budg...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Cell Biology Physics of Living Systems Source Type: research

Correction: Imaging neuropeptide release at synapses with a genetically engineered reporter
(Source: eLife)
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

MouseBytes, an open-access high-throughput pipeline and database for rodent touchscreen-based cognitive assessment
Open Science has changed research by making data accessible and shareable, contributing to replicability to accelerate and disseminate knowledge. However, for rodent cognitive studies the availability of tools to share and disseminate data is scarce. Automated touchscreen-based tests enable systematic cognitive assessment with easily standardized outputs that can facilitate data dissemination. Here we present an integration of touchscreen cognitive testing with an open-access database public repository (mousebytes.ca), as well as a Web platform for knowledge dissemination (https://touchscreencognition.org). We complement t...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

The computation of directional selectivity in the Drosophila OFF motion pathway
In flies, the direction of moving ON and OFF features is computed separately. T4 (ON) and T5 (OFF) are the first neurons in their respective pathways to extract a directionally selective response from their non-selective inputs. Our recent study of T4 found that the integration of offset depolarizing and hyperpolarizing inputs is critical for the generation of directional selectivity. However, T5s lack small-field inhibitory inputs, suggesting they may use a different mechanism. Here we used whole-cell recordings of T5 neurons and found a similar receptive field structure: fast depolarization and persistent, spatially offs...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Diversification of the < i > Caenorhabditis < /i > heat shock response by Helitron transposable elements
Heat Shock Factor 1 (HSF-1) is a key regulator of the heat shock response (HSR). Upon heat shock, HSF-1 binds well-conserved motifs, called Heat Shock Elements (HSEs), and drives expression of genes important for cellular protection during this stress. Remarkably, we found that substantial numbers of HSEs in multipleCaenorhabditis species reside within Helitrons, a type of DNA transposon. Consistent with Helitron-embedded HSEs being functional, upon heat shock they display increased HSF-1 and RNA polymerase II occupancy and up-regulation of nearby genes inC. elegans. Interestingly, we found that different genes appear to b...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Genetics and Genomics Source Type: research

Agonist-specific voltage-dependent gating of lysosomal two-pore Na < sup > + < /sup > channels
Mammalian two-pore-channels (TPC1, 2;TPCN1, TPCN2) are ubiquitously- expressed, PI(3,5)P2-activated, Na+-selective channels in the endosomes and lysosomes that regulate luminal pH homeostasis, membrane trafficking, andEbola viral infection. Whereas the channel activity of TPC1 is strongly dependent on membrane voltage, TPC2 lacks such voltage dependence despite the presence of the presumed ‘S4 voltage-sensing’ domains. By performing high-throughput screening followed by lysosomal electrophysiology, here we identified a class of tricyclic anti-depressants (TCAs) as small-molecule agonists of TPC channels. TCAs a...
Source: eLife - December 11, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Long-lived metabolic enzymes in the crystalline lens identified by pulse-labeling of mice and mass spectrometry
The lenticular fiber cells are comprised of extremely long-lived proteins while still maintaining an active biochemical state. Dysregulation of these activities has been implicated in diseases such as age-related cataracts. However, the lenticular protein dynamics underlying health and disease is unclear. We sought to measure the global protein turnover rates in the eye using nitrogen-15 labeling of mice and mass spectrometry. We measured the14N/15N-peptide ratios of 248 lens proteins, including Crystallin, Aquaporin, Collagen and enzymes that catalyze glycolysis and oxidation/reduction reactions. Direct comparison of lens...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Source Type: research

Modelling survival
A new mouse model of sepsis can reproduce the long-term muscle weakness seen in patients who survive this life-threatening illness. (Source: eLife)
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Human Biology and Medicine Immunology and Inflammation Source Type: research

Dzip1 and Fam92 form a ciliary transition zone complex with cell type specific roles in < i > Drosophila < /i >
Cilia and flagella are conserved eukaryotic organelles essential for cellular signaling and motility. Cilia dysfunctions cause life-threatening ciliopathies, many of which are due to defects in the transition zone (TZ), a complex structure of the ciliary base. Therefore, understanding TZ assembly, which relies on ordered interactions of multiprotein modules, is of critical importance. Here, we show thatDrosophila Dzip1 and Fam92 form a functional module which constrains the conserved core TZ protein, Cep290, to the ciliary base. We identify cell type specific roles of this functional module in two different tissues. While ...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Cell Biology Developmental Biology Source Type: research

mTORC1 in the orbitofrontal cortex promotes habitual alcohol seeking
The mechanistic target of rapamycin complex 1 (mTORC1) plays an important role in dendritic translation and in learning and memory. We previously showed that heavy alcohol use activates mTORC1 in the orbitofrontal cortex (OFC) of rodents (1). Here, we set out to determine the consequences of alcohol-dependent mTORC1 activation in the OFC. We found that inhibition of mTORC1 activity attenuates alcohol seeking and restores sensitivity to outcome devaluation in rats that habitually seek alcohol. In contrast, habitual responding for sucrose was unaltered by mTORC1 inhibition, suggesting that mTORC1's role in habitual behavior ...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Broadly neutralizing human antibodies against dengue virus identified by single B cell transcriptomics
Eliciting broadly neutralizing antibodies (bNAbs) against the four dengue virus serotypes (DENV1-4) that are spreading into new territories is an important goal of vaccine design. To define bNAb targets, we characterized 28 antibodies belonging to expanded and hypermutated clonal families identified by transcriptomic analysis of single plasmablasts from DENV-infected individuals. Among these, we identified J9 and J8, two somatically related bNAbs that potently neutralized DENV1-4. Mutagenesis studies showed that the major recognition determinants of these bNAbs are in E protein domain I, distinct from the only known class ...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Immunology and Inflammation Microbiology and Infectious Disease Source Type: research

Long-lived metabolic enzymes in the Crystallin lens identified by pulse-labeling of mice and mass spectrometry
The lenticular fiber cells are comprised of extremely long-lived proteins while still maintaining an active biochemical state. Dysregulation of these activities has been implicated in diseases such as age-related cataracts. However, the lenticular protein dynamics underlying health and disease is unclear. We sought to measure the global protein turnover rates in the eye using nitrogen-15 labeling of mice and mass spectrometry. We measured the14N/15N-peptide ratios of 248 lens proteins, including Crystallin, Aquaporin, Collagen and enzymes that catalyze glycolysis and oxidation/reduction reactions. Direct comparison of lens...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Source Type: research

Retinal oxygen supply shaped the functional evolution of the vertebrate eye
The retina has a very high energy demand but lacks an internal blood supply in most vertebrates. Here we explore the hypothesis that oxygen diffusion limited the evolution of retinal morphology by reconstructing the evolution of retinal thickness and the various mechanisms for retinal oxygen supply, including capillarization and acid-induced haemoglobin oxygen unloading. We show that a common ancestor of bony fishes likely had a thin retina without additional retinal oxygen supply mechanisms and that three different types of retinal capillaries were gained and lost independently multiple times during the radiation of verte...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Evolutionary Biology Source Type: research

Linking glycemic dysregulation in diabetes to symptoms, comorbidities, and genetics through EHR data mining
Diabetes is a diverse and complex disease, with considerable variation in phenotypic manifestation and severity. This variation hampers the study of etiological differences and reduces the statistical power of analyses of associations to genetics, treatment outcomes, and complications. We address these issues through deep, fine-grained phenotypic stratification of a diabetes cohort. Text mining the electronic health records of 14,017 patients, we matched two controlled vocabularies (ICD-10 and a custom vocabulary developed at the clinical center Steno Diabetes Center Copenhagen) to clinical narratives spanning a 19 year pe...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Computational and Systems Biology Epidemiology and Global Health Source Type: research

Local cortical desynchronization and pupil-linked arousal differentially shape brain states for optimal sensory performance
Instantaneous brain states have consequences for our sensation, perception, and behaviour. Fluctuations in arousal and neural desynchronization likely pose perceptually relevant states. However, their relationship and their relative impact on perception is unclear. We here show that, at the single-trial level in humans, local desynchronization in sensory cortex (expressed as time-series entropy) versus pupil-linked arousal differentially impact perceptual processing. While we recorded electroencephalography (EEG) and pupillometry data, stimuli of a demanding auditory discrimination task were presented into states of high o...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

A novel lineage of candidate pheromone receptors for sex communication in moths
Sex pheromone receptors (PRs) are key players in chemical communication between mating partners in insects. In the highly diversified insect order Lepidoptera, male PRs tuned to female-emitted type I pheromones (which make up the vast majority of pheromones identified) form a dedicated subfamily of odorant receptors (ORs). Here, using a combination of heterologous expression and in vivo genome editing methods, we bring functional evidence that at least one moth PR does not belong to this subfamily but to a distantly related OR lineage. This PR, identified in the cotton leafwormSpodoptera littoralis, is highly expressed in ...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Evolutionary Biology Neuroscience Source Type: research

Neural ensemble dynamics in dorsal motor cortex during speech in people with paralysis
Speaking is a sensorimotor behavior whose neural basis is difficult to study with single neuron resolution due to the scarcity of human intracortical measurements. We used electrode arrays to record from the motor cortex 'hand knob' in two people with tetraplegia, an area not previously implicated in speech. Neurons modulated during speaking and during non-speaking movements of the tongue, lips, and jaw. This challenges whether the conventional model of a 'motor homunculus' division by major body regions extends to the single-neuron scale. Spoken words and syllables could be decoded from single trials, demonstrating the po...
Source: eLife - December 10, 2019 Category: Biomedical Science Tags: Human Biology and Medicine Neuroscience Source Type: research

B cells extract antigens at Arp2/3-generated actin foci interspersed with linear filaments
Antibody production depends on B cell internalization and presentation of antigens to helper T cells. To acquire antigens displayed by antigen-presenting cells, B cells form immune synapses and extract antigens by the mechanical activity of the acto-myosin cytoskeleton. While cytoskeleton organization driving the initial formation of the B cell synapse has been studied, how the cytoskeleton supports antigen extraction remains poorly understood. Here we show that after initial cell spreading, F-actin in synapses of primary mouse B cells and human B cell lines forms a highly dynamic pattern composed of actin foci intersperse...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Cell Biology Immunology and Inflammation Source Type: research

Vasohibin1, a new mouse cardiomyocyte IRES trans-acting factor that regulates translation during early hypoxia
Hypoxia, a major inducer of angiogenesis, triggers major changes of gene expression at the transcriptional level. Furthermore, global protein synthesis is blocked while internal ribosome entry sites (IRES) allow specific mRNAs to be translated. Here we report the transcriptome and translatome signatures of (lymph)angiogenic genes in hypoxic HL-1 mouse cardiomyocytes: most genes are induced at the translatome level, including all IRES-containing mRNAs. Our data reveal activation of (lymph)angiogenic factor mRNA IRESs in early hypoxia. We identify vasohibin1 (VASH1) as an IRES trans-acting factor (ITAF) able to bind RNA and ...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Cell Biology Chromosomes and Gene Expression Source Type: research

Probe-Seq enables transcriptional profiling of specific cell types from heterogeneous tissue by RNA-based isolation
Recent transcriptional profiling technologies are uncovering previously-undefined cell populations and molecular markers at an unprecedented pace. While single cell RNA (scRNA) sequencing is an attractive approach for unbiased transcriptional profiling of all cell types, a complementary method to isolate and sequence specific cell populations from heterogeneous tissue remains challenging. Here, we developed Probe-Seq, which allows deep transcriptional profiling of specific cell types isolated using RNA as the defining feature. Dissociated cells are labeled using fluorescent in situ hybridization (FISH) for RNA, and then is...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Genetics and Genomics Neuroscience Source Type: research

Mutations that improve efficiency of a weak-link enzyme are rare compared to adaptive mutations elsewhere in the genome
New enzymes often evolve by gene amplification and divergence. Previous experimental studies have followed the evolutionary trajectory of an amplified gene, but have not considered mutations elsewhere in the genome when fitness is limited by an evolving gene. We have evolved a strain ofEscherichia coli in which a secondary promiscuous activity has been recruited to serve an essential function. The gene encoding the 'weak-link' enzyme amplified in all eight populations, but mutations improving the newly needed activity occurred in only one. Most adaptive mutations occurred elsewhere in the genome. Some mutations increase ex...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Sequential phosphorylation of NDEL1 by the DYRK2-GSK3 β complex is critical for neuronal morphogenesis
Neuronal morphogenesis requires multiple regulatory pathways to appropriately determine axonal and dendritic structures, thereby to enable the functional neural connectivity. Yet, however, the precise mechanisms and components that regulate neuronal morphogenesis are still largely unknown. Here, we newly identified the sequential phosphorylation of NDEL1 critical for neuronal morphogenesis through the human kinome screening and phospho-proteomics analysis of NDEL1 from mouse brain lysate. DYRK2 phosphorylates NDEL1 S336 to prime the phosphorylation of NDEL1 S332 by GSK3b. TARA, an interaction partner of NDEL1, scaffolds DY...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Developmental Biology Neuroscience Source Type: research

Repressive H3K9me2 protects lifespan against the transgenerational burden of COMPASS activity in < i > C. elegans < /i >
InCaenorhabditis elegans, mutations in WDR-5 and other components of the COMPASS H3K4 methyltransferase complex extend lifespan and enable its inheritance. Here we show thatwdr-5 mutant longevity is itself a transgenerational trait that corresponds with a global enrichment of the heterochromatin factor H3K9me2 over twenty generations. In addition, we find that the transgenerational aspects ofwdr-5 mutant longevity require the H3K9me2 methyltransferase MET-2, and can be recapitulated by removal of the putative H3K9me2 demethylase JHDM-1. Finally, we show that the transgenerational acquisition of longevity injhdm-1 mutants i...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Chromosomes and Gene Expression Genetics and Genomics Source Type: research

Amyloid and tau accumulate across distinct spatial networks and are differentially associated with brain connectivity
In this study, we applied a joint independent component analysis to18F- Flutemetamol (amyloid- β) and18F-Flortaucipir (tau) PET images to identify amyloid- β and tau networks across different stages of Alzheimer's disease. We then assessed whether these patterns were associated with resting-state functional networks and white matter tracts. Our analyses revealed nine patterns that were linked across tau and amyloid-β data. The amyloid-b and tau patte rns showed a fair to moderate overlap with distinct functional networks but only tau was associated with white matter integrity loss and multiple cognitive func...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Molecular structures of the human Slo1 K < sup > + < /sup > channel in complex with β4
This study presents cryo-EM structures of Slo1 in complex with the auxiliary protein, β4. Four β4, each containing two transmembrane helices, encircle Slo1, contacting it through helical interactions inside the membrane. On the extracellular side, b4 forms a tetrameric crown over the pore. Structures with high and low Ca2+ concentrations show that identical gating conformations occur in the absence and presence of β4, implying that β4 serves to modulate the relative stabilities of 'pre-existing' conformations rather than creating new ones. The effects of β4 on scorpion toxin inhibition kinetics are...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Two new polymorphic structures of human full-length alpha-synuclein fibrils solved by cryo-electron microscopy
Intracellular inclusions rich in alpha-synuclein are a hallmark of several neuropathological diseases including Parkinson's disease (PD). Previously, we reported the structure of alpha-synuclein fibrils (residues 1-121), composed of two protofibrils that are connected via a densely-packed interface formed by residues 50-57 (Guerrero-Ferreira, eLife 218;7:e36402). We here report two new polymorphic atomic structures of alpha-synuclein fibrils termed polymorphs 2a and 2b, at 3.0 Å and 3.4 Å resolution, respectively. These polymorphs show a radically different structure compared to previously reported polymorphs. ...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Neuroscience Structural Biology and Molecular Biophysics Source Type: research

Calpain fosters the hyperexcitability of motoneurons after spinal cord injury and leads to spasticity
Up-regulation of the persistent sodium current (INaP) and down-regulation of the potassium/chloride extruder KCC2 lead to spasticity after spinal cord injury (SCI). We here identified calpain as the driver of the up- and down-regulation ofINaP andKCC2, respectively, in neonatal rat lumbar motoneurons. Few days after SCI, neonatal rats developed behavioral signs of spasticity with the emergence of both hyperreflexia and abnormal involuntary muscle contractions on hindlimbs. At the same time,in vitro isolated lumbar spinal cords became hyperreflexive and displayed numerous spontaneous motor outputs. Calpain-I expression para...
Source: eLife - December 9, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Spatiotemporal dynamics and heterogeneity of renal lymphatics in mammalian development and cystic kidney disease
Heterogeneity of lymphatic vessels during embryogenesis is critical for organ-specific lymphatic function. Little is known about lymphatics in the developing kidney, despite their established roles in pathology of the mature organ. We performed three-dimensional imaging to characterize lymphatic vessel formation in the mammalian embryonic kidney at single-cell resolution. In mouse, we visually and quantitatively assessed the development of kidney lymphatic vessels, remodeling from a ring-like anastomosis under the nascent renal pelvis, a site of VEGF-C expression, to form a patent vascular plexus. We identified a heterogen...
Source: eLife - December 6, 2019 Category: Biomedical Science Tags: Developmental Biology Human Biology and Medicine Source Type: research