Shear stress activates ADAM10 sheddase to regulate Notch1 via the Piezo1 force sensor in endothelial cells
Mechanical force is a determinant of Notch signalling but the mechanism of force detection and its coupling to Notch are unclear. We propose a role for Piezo1 channels, which are mechanically-activated non-selective cation channels. In cultured microvascular endothelial cells, Piezo1 channel activation by either shear stress or a chemical agonist Yoda1 activated a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), a Ca2+-regulated transmembrane sheddase that mediates S2 Notch1 cleavage. Consistent with this observation, we found Piezo1-dependent increase in the abundance of Notch1 intracellular domain...
Source: eLife - June 2, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

TMEM95 is a sperm membrane protein essential for mammalian fertilization
The fusion of gamete membranes during fertilization is an essential process for sexual reproduction. Despite its importance, only three proteins are known to be indispensable for sperm-egg membrane fusion: the sperm proteins IZUMO1 and SPACA6, and the egg protein JUNO. Here we demonstrate that another sperm protein, TMEM95, is necessary for sperm-egg interaction. TMEM95 ablation in mice caused complete male-specific infertility. Sperm lacking this protein were morphologically normal exhibited normal motility, and could penetrate the zona pellucida and bind to the oolemma. However, once bound to the oolemma, TMEM95-deficien...
Source: eLife - June 2, 2020 Category: Biomedical Science Tags: Cell Biology Developmental Biology Source Type: research

Dynamic metastable long-living droplets formed by sticker-spacer proteins
Multivalent biopolymers phase separate into membrane-less organelles (MLOs) which exhibit liquid-like behavior. Here, we explore formation of prototypical MOs from multivalent proteins on various time and length scales and show that the kinetically arrested metastable multi-droplet state is a dynamic outcome of the interplay between two competing processes: a diffusion-limited encounter between proteins, and the exhaustion of available valencies within smaller clusters. Clusters with satisfied valencies cannot coalesce readily, resulting in metastable, long-living droplets. In the regime of dense clusters akin to phase-sep...
Source: eLife - June 2, 2020 Category: Biomedical Science Tags: Physics of Living Systems Structural Biology and Molecular Biophysics Source Type: research

Hyperalignment: Modeling shared information encoded in idiosyncratic cortical topographies
Information that is shared across brains is encoded in idiosyncratic fine-scale functional topographies. Hyperalignment captures shared information by projecting pattern vectors for neural responses and connectivities into a common, high-dimensional information space, rather than by aligning topographies in a canonical anatomical space. Individual transformation matrices project information from individual anatomical spaces into the common model information space, preserving the geometry of pairwise dissimilarities between pattern vectors, and model cortical topography as mixtures of overlapping, individual-specific topogr...
Source: eLife - June 2, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Diverse homeostatic and immunomodulatory roles of immune cells in the developing mouse lung at single cell resolution
At birth, the lungs rapidly transition from a pathogen-free, hypoxic environment to a pathogen-rich, rhythmically distended air-liquid interface. Although many studies have focused on the adult lung, the perinatal lung remains unexplored. Here, we present an atlas of the murine lung immune compartment during early postnatal development. We show that the late embryonic lung is dominated by specialized proliferative macrophages with a surprising physical interaction with the developing vasculature. These macrophages disappear after birth and are replaced by a dynamic mixture of macrophage subtypes, dendritic cells, granulocy...
Source: eLife - June 2, 2020 Category: Biomedical Science Tags: Developmental Biology Immunology and Inflammation Source Type: research

Correction: Collective forces of tumor spheroids in three-dimensional biopolymer networks
(Source: eLife)
Source: eLife - June 2, 2020 Category: Biomedical Science Tags: Cancer Biology Physics of Living Systems Source Type: research

Tissue resident macrophages promote extracellular matrix homeostasis in the mammary gland stroma of nulliparous mice
Tissue resident macrophages in the mammary gland are found in close association with epithelial structures and within the adipose stroma, and are important for mammary gland development and tissue homeostasis. While macrophages have been linked to ductal development in the virgin mammary gland, less is known regarding the effects of macrophages on the adipose stroma. Using transcriptional profiling and single cell RNA sequencing approaches, we identify a distinct resident stromal macrophage subpopulation within the mouse nulliparous mammary gland characterized by expression of Lyve-1, a receptor for the extracellular matri...
Source: eLife - June 1, 2020 Category: Biomedical Science Tags: Developmental Biology Immunology and Inflammation Source Type: research

KRAB-zinc finger protein gene expansion in response to active retrotransposons in the murine lineage
The Kr üppel-associated box zinc finger protein (KRAB-ZFP) family diversified in mammals. The majority of human KRAB-ZFPs bind transposable elements (TEs), however, since most TEs are inactive in humans it is unclear whether KRAB-ZFPs emerged to suppress TEs. We demonstrate that many recently emerged muri ne KRAB-ZFPs also bind to TEs, including the active ETn, IAP, and L1 families. Using a CRISPR/Cas9-based engineering approach, we genetically deleted five large clusters of KRAB-ZFPs and demonstrate that target TEs are de-repressed, unleashing TE-encoded enhancers. Homozygous knockout mice lacking o ne of two KRAB-ZF...
Source: eLife - June 1, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Genetics and Genomics Source Type: research

A Bayesian and efficient observer model explains concurrent attractive and repulsive history biases in visual perception
Human perceptual decisions can be repelled away from (repulsive adaptation) or attracted towards recent visual experience (attractive serial dependence). It is currently unclear whether and how these repulsive and attractive biases interact during visual processing and what computational principles underlie these history dependencies. Here we disentangle repulsive and attractive biases by exploring their respective timescales. We find that perceptual decisions are concurrently attracted towards the short-term perceptual history and repelled from stimuli experienced up to minutes into the past. The temporal pattern of short...
Source: eLife - June 1, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Retrocopying expands the functional repertoire of APOBEC3 antiviral proteins in primates
Host-virus arms races are inherently asymmetric; viruses evolve much more rapidly than host genomes. Thus, there is high interest in discovering mechanisms by which host genomes keep pace with rapidly evolving viruses. One family of restriction factors, theAPOBEC3 (A3) cytidine deaminases, has undergone positive selection and expansion via segmental gene duplication and recombination. Here, we show that new copies ofA3 genes have also been created in primates by reverse transcriptase-encoding elements like LINE-1 or endogenous retroviruses via a process termed retrocopying. First, we discovered that all simian primate geno...
Source: eLife - June 1, 2020 Category: Biomedical Science Tags: Evolutionary Biology Microbiology and Infectious Disease Source Type: research

The copy-number and varied strength of MELT motifs in Spc105 balance the strength and responsiveness of the Spindle Assembly Checkpoint
The Spindle Assembly Checkpoint (SAC) maintains genome stability while ensuring timely anaphase onset. To maintain genome stability, it must be strong to delay cell division even if one chromosome is unattached, but for timely anaphase onset, it must promptly respond to silencing mechanisms. How the SAC meets these potentially antagonistic requirements is unclear. Here we show that the balance between SAC strength and responsiveness is determined by the number of 'MELT' motifs in the kinetochore protein Spc105/KNL1 and their Bub3-Bub1 binding affinities. Many strong MELT motifs per Spc105/KNL1 minimize chromosome missegreg...
Source: eLife - June 1, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

< i > Plasmodium falciparum < /i > translational machinery condones polyadenosine repeats
Plasmodium falciparum is causative agent of human malaria. Sixty percent of mRNAs from its extremely AT-rich (81%) genome harbor long polyadenosine (polyA) runs within their ORFs, distinguishing the parasite from its hosts and other sequenced organisms. Recent studies indicate polyA runs cause ribosome stalling and frameshifting, triggering mRNA surveillance pathways and attenuating protein synthesis. Here, we show that theP. falciparum is an exception to this rule. We demonstrate that both endogenous genes and reporter sequences containing long polyA runs are efficiently and accurately translated inP. falciparum cells. We...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

Bioengineering horizon scan 2020
Horizon scanning is intended to identify the opportunities and threats associated with technological, regulatory and social change. In 2017 some of the present authors conducted a horizon scan for bioengineering (Wintle et al., 2017). Here we report the results of a new horizon scan that is based on inputs from a larger and more international group of 38 participants. The final list of 20 issues includes topics spanning from the political (the regulation of genomic data, increased philanthropic funding and malicious uses of neurochemicals) to the environmental (crops for changing climates and agricultural gene drives). The...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Genetics and Genomics Human Biology and Medicine Source Type: research

PrkA controls peptidoglycan biosynthesis through the essential phosphorylation of ReoM
Peptidoglycan (PG) is the main component of bacterial cell walls and the target for many antibiotics. PG biosynthesis is tightly coordinated with cell wall growth and turnover, and many of these control activities depend upon PASTA-domain containing eukaryotic-like serine/threonine protein kinases (PASTA-eSTK) that sense PG fragments. However, only a few PG biosynthetic enzymes are direct kinase substrates. Here, we identify the conserved ReoM protein as a novel PASTA-eSTK substrate in the Gram-positive pathogenListeria monocytogenes. Our data show that the phosphorylation of ReoM is essential as it controls ClpCP-dependen...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Universally high transcript error rates in bacteria
Errors can occur at any level during the replication and transcription of genetic information. Genetic mutations derived mainly from replication errors have been extensively studied. However, fundamental details of transcript errors, such as their rate, molecular spectrum, and functional effects, remain largely unknown. To globally identify transcript errors, we applied an adapted rolling-circle sequencing approach toEscherichia coli,Bacillus subtilis,Agrobacterium tumefaciens, andMesoplasma florum, revealing transcript-error rates 3 to 4 orders of magnitude higher than the corresponding genetic mutation rates. The majorit...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Genetics and Genomics Source Type: research

< i > Lin28a/let-7 < /i > pathway modulates the < i > Hox < /i > code via < i > Polycomb < /i > regulation during axial patterning in vertebrates
In this study, we demonstrated that theLin28a/let-7 pathway is critical for axial elongation.Lin28a–/– mice exhibited axial shortening with mild skeletal transformations of vertebrae, which were consistent with results in mice with tail bud-specific mutants of Lin28a. The accumulation oflet-7 inLin28a–/– mice resulted in the reduction of PRC1 occupancy at theHox cluster loci by targetingCbx2. Consistently, Lin28a loss in embryonic stem-like cells led to aberrant induction of posteriorHox genes, which was rescued by the knockdown oflet-7. These results suggest that theLin28/let-7 pathway is involved ...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Distinct interactions of eIF4A and eIF4E with RNA helicase Ded1 stimulate translation in vivo
Yeast DEAD-box helicase Ded1 stimulates translation initiation, particularly of mRNAs with structured 5'UTRs. Interactions of the Ded1 N-terminal domain (NTD) with eIF4A, and Ded1-CTD with eIF4G, subunits of eIF4F, enhance Ded1 unwinding activity and stimulation of preinitiation complex (PIC) assembly in vitro. However, the importance of these interactions, and of Ded1-eIF4E association, in vivo were poorly understood. We identified separate amino-acid clusters in the Ded1-NTD required for binding to eIF4A or eIF4E in vitro. Disrupting each cluster selectively impairs native Ded1 association with eIF4A or eIF4E, and reduce...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Source Type: research

Hippocampal and cortical mechanisms at retrieval explain variability in episodic remembering in older adults
Age-related episodic memory decline is characterized by striking heterogeneity across individuals. Hippocampal pattern completion is a fundamental process supporting episodic memory. Yet, the degree to which this mechanism is impaired with age, and contributes to variability in episodic memory, remains unclear. We combine univariate and multivariate analyses of fMRI data from a large cohort of cognitively normal older adults (N=100) to measure hippocampal activity and cortical reinstatement during retrieval of trial-unique associations. Trial-wise analyses revealed that (a) hippocampal activity scaled with reinstatement st...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Genomic and phenotypic evolution of < i > Escherichia coli < /i > in a novel citrate-only resource environment
Evolutionary innovations allow populations to colonize new ecological niches. We previously reported that aerobic growth on citrate (Cit+) evolved in anEscherichia coli population during adaptation to a minimal glucose medium containing citrate (DM25). Cit+ variants can also grow in citrate-only medium (DM0), a novel environment forE. coli. To study adaptation to this new niche, we founded two sets of Cit+ populations and evolved them for 2,500 generations in DM0 or DM25. The evolved lineages acquired numerous parallel mutations, many mediated by transposable elements. Several also evolved amplifications of regions contain...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Structure of substrate-bound SMG1-8-9 kinase complex reveals molecular basis for phosphorylation specificity
PI3K-related kinases (PIKKs) are large Serine/Threonine (Ser/Thr)-protein kinases central to the regulation of many fundamental cellular processes. PIKK family member SMG1 orchestrates progression of an RNA quality control pathway, termed nonsense-mediated mRNA decay (NMD), by phosphorylating the NMD factor UPF1. Phosphorylation of UPF1 occurs in its unstructured N- and C-terminal regions at Serine/Threonine-Glutamine (SQ) motifs. How SMG1 and other PIKKs specifically recognize SQ motifs has remained unclear. Here, we present a cryo-electron microscopy (cryo-EM) reconstruction of a human SMG1-8-9 kinase complex bound to a ...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Spatial inter-centromeric interactions facilitated the emergence of evolutionary new centromeres
Centromeres ofCandida albicans form on unique and different DNA sequences but a closely related species,Candida tropicalis, possesses homogenized inverted repeat (HIR)-associated centromeres. To investigate the mechanism of centromere type transition, we improved the fragmented genome assembly and constructed a chromosome-level genome assembly ofC. tropicalis by employing PacBio sequencing, chromosome conformation capture sequencing (3C-seq), chromoblot, and genetic analysis of engineered aneuploid strains. Further, we analyzed the 3D genome organization using 3C-seq data, which revealed spatial proximity among the centrom...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Genetics and Genomics Source Type: research

Conformational distributions of isolated myosin motor domains encode their mechanochemical properties
Myosin motor domains perform an extraordinary diversity of biological functions despite sharing a common mechanochemical cycle. Motors are adapted to their function, in part, by tuning the thermodynamics and kinetics of steps in this cycle. However, it remains unclear how sequence encodes these differences, since biochemically distinct motors often have nearly indistinguishable crystal structures. We hypothesized that sequences produce distinct biochemical phenotypes by modulating the relative probabilities of an ensemble of conformations primed for different functional roles. To test this hypothesis, we modeled the distri...
Source: eLife - May 29, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Structural Biology and Molecular Biophysics Source Type: research

True S-cones are concentrated in the ventral mouse retina and wired for color detection in the upper visual field
Color, an important visual cue for survival, is encoded by comparing signals from photoreceptors with different spectral sensitivities. The mouse retina expresses a short wavelength-sensitive and a middle/long wavelength-sensitive opsin (S- and M-opsin), forming opposing, overlapping gradients along the dorsal-ventral axis. Here, we analyzed the distribution of all cone types across the entire retina for two commonly used mouse strains. We found, unexpectedly, that 'true S-cones' (S-opsin only) are highly concentrated (up to 30% of cones) in ventral retina. Moreover, S-cone bipolar cells (SCBCs) are also skewed towards ven...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Evolutionary Biology Neuroscience Source Type: research

Knowledge synthesis of 100 million biomedical documents augments the deep expression profiling of coronavirus receptors
The COVID-19 pandemic demands assimilation of all biomedical knowledge to decode mechanisms of pathogenesis. Despite the recent renaissance in neural networks, a platform for the real-time synthesis of the exponentially growing biomedical literature and deep omics insights is unavailable. Here, we present the nferX platform for dynamic inference from 45 quadrillion+ possible conceptual associations from unstructured text and triangulation with insights from Single Cell RNA-sequencing, bulk RNAseq and proteomics from diverse tissue types. A hypothesis-free profiling of ACE2 suggests tongue keratinocytes, olfactory epithelia...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Human Biology and Medicine Source Type: research

Integrative analysis of large-scale loss-of-function screens identifies robust cancer-associated genetic interactions
Genetic interactions, including synthetic lethal effects, can now be systematically identified in cancer cell lines using high-throughput genetic perturbation screens. Despite this advance, few genetic interactions have been reproduced across multiple studies and many appear highly context-specific. Here, by developing a new computational approach, we identified 220 robust driver-gene associated genetic interactions that can be reproduced across independent experiments and across non-overlapping cell line panels. Analysis of these interactions demonstrated that: (i) oncogene addiction effects are more robust than oncogene-...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Cancer Biology Computational and Systems Biology Source Type: research

Distinct mitochondrial defects trigger the integrated stress response depending on the metabolic state of the cell
Mitochondrial dysfunction is associated with activation of the integrated stress response (ISR) but the underlying triggers remain unclear. We systematically combined acute mitochondrial inhibitors with genetic tools for compartment-specific NADH oxidation to trace mechanisms linking different forms of mitochondrial dysfunction to the ISR in proliferating mouse myoblasts and in differentiated myotubes. In myoblasts, we find that impaired NADH oxidation upon electron transport chain (ETC) inhibition depletes asparagine, activating the ISR via the eIF2 α kinase GCN2. In myotubes, however, impaired NADH oxidation follow...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Genetics and Genomics Human Biology and Medicine Source Type: research

FRET kinase sensor development reveals SnRK2/OST1 activation by ABA but not by MeJA and high CO < sub > 2 < /sub > during stomatal closure
We report a potent approach for real-time live-cell investigations of stress signaling. (Source: eLife)
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Plant Biology Source Type: research

Sculpting new structures
The origins of the posterior lobe, a recently evolved structure in some species ofDrosophila, have become clearer. (Source: eLife)
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Developmental Biology Evolutionary Biology Source Type: research

A survey of travel behaviour among scientists in Germany and the potential for change
Awareness of the environmental impact of conferences is growing within the scientific community. Here we report the results of a survey in which scientists in Germany were asked about their attendance at conferences, their reasons for attending, and their willingness to explore new approaches that would reduce the impact of conferences on the environment. A majority of respondents were keen to reduce their own carbon footprint and were willing to explore alternatives to the traditional conference. (Source: eLife)
Source: eLife - May 28, 2020 Category: Biomedical Science Source Type: research

Phagocytic glia are obligatory intermediates in transmission of mutant huntingtin aggregates across neuronal synapses
Emerging evidence supports the hypothesis that pathogenic protein aggregates associated with neurodegenerative diseases spread from cell to cell through the brain in a manner akin to infectious prions. Here, we show that mutant huntingtin (mHtt) aggregates associated with Huntington disease transfer anterogradely from presynaptic to postsynaptic neurons in the adultDrosophila olfactory system. Trans-synaptic transmission of mHtt aggregates is inversely correlated with neuronal activity and blocked by inhibiting caspases in presynaptic neurons, implicating synaptic dysfunction and cell death in aggregate spreading. Remarkab...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Cell Biology Neuroscience Source Type: research

Genomic innovation of ATD alleviates mistranslation associated with multicellularity in Animalia
The emergence of multicellularity in Animalia is associated with increase in ROS and expansion of tRNA-isodecoders. tRNA expansion leads to misselection resulting in a critical error of L-Ala mischarged onto tRNAThr, which is proofread by Animalia-specific-tRNA Deacylase (ATD)in vitro. Here we show that in addition to ATD, threonyl-tRNA synthetase (ThrRS) can clear the error in cellular scenario. This two-tier functional redundancy for translation quality control breaks down during oxidative stress, wherein ThrRS is rendered inactive. Therefore, ATD knockout cells display pronounced sensitivity through increased mistransla...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Source Type: research

Apical length governs computational diversity of layer 5 pyramidal neurons
Anatomical similarity across the neocortex has led to the common assumption that the circuitry is modular and performs stereotyped computations. Layer 5 pyramidal neurons (L5PNs) in particular are thought to be central to cortical computation because of their extensive arborisation and nonlinear dendritic operations. Here, we demonstrate that computations associated with dendritic Ca2+ plateaus in mouse L5PNs vary substantially between the primary and secondary visual cortices. L5PNs in the secondary visual cortex show reduced dendritic excitability and smaller propensity for burst firing. This reduced excitability is corr...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

< i > TUBB4A < /i > mutations result in both glial and neuronal degeneration in an H-ABC leukodystrophy mouse model
Mutations inTUBB4A result in a spectrum of leukodystrophy including Hypomyelination with Atrophy of Basal Ganglia and Cerebellum (H-ABC), a rare hypomyelinating leukodystrophy, often associated with a recurring variant p.Asp249Asn (D249N). We have developed a novel knock-in mouse model harboring heterozygous (Tubb4aD249N/+) and the homozygous (Tubb4aD249N/D249N) mutation that recapitulate the progressive motor dysfunction with tremor, dystonia and ataxia seen in H-ABC.Tubb4aD249N/D249N mice have myelination deficits along with dramatic decrease in mature oligodendrocytes and their progenitor cells. Additionally, a signific...
Source: eLife - May 28, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

MicroRNA-934 is a novel primate-specific small non-coding RNA with neurogenic function during early development
Integrating differential RNA and miRNA expression during neuronal lineage induction of human embryonic stem cells we identified miR-934, a primate-specific miRNA that displays a stage-specific expression pattern during progenitor expansion and early neuron generation. We demonstrate the biological relevance of this finding by comparison with data from early to mid-gestation human cortical tissue. Further we find that miR-934 directly controls progenitor to neuroblast transition and impacts on neurite growth of newborn neurons. In agreement, miR-934 targets are involved in progenitor proliferation and neuronal differentiati...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Epigenetic inheritance of circadian period in clonal cells
Circadian oscillations are generated via transcriptional-translational negative feedback loops. However, individual cells from fibroblast cell lines have heterogeneous rhythms, oscillating independently and with different period lengths. Here we showed that heterogeneity in circadian period is heritable and used a multi-omics approach to investigate underlying mechanisms. By examining large-scale phenotype-associated gene expression profiles in hundreds of mouse clonal cell lines, we identified and validated multiple novel candidate genes involved in circadian period determination in the absence of significant genomic vari...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Struggling to get started
As the world attempts to cope with the devastating impact of the COVID-19 pandemic, researchers about to start PhDs and postdocs face particular challenges. (Source: eLife)
Source: eLife - May 27, 2020 Category: Biomedical Science Source Type: research

Characterization of the kinetic cycle of an ABC transporter by single-molecule and cryo-EM analyses
ATP-binding cassette (ABC) transporters are molecular pumps ubiquitous across all kingdoms of life. While their structures have been widely reported, the kinetics governing their transport cycles remain largely unexplored. Multidrug resistance protein 1 (MRP1) is an ABC exporter that extrudes a variety of chemotherapeutic agents and native substrates. Previously, the structures of MRP1 were determined in an inward-facing (IF) or outward-facing (OF) conformation. Here, we used single-molecule fluorescence spectroscopy to track the conformational changes of bovine MRP1 (bMRP1) in real time. We also determined the structure o...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Transgenesis and web resources in quail
Due to its amenability to manipulations, to live observation and its striking similarities to mammals, the chicken embryo has been one of the major animal models in biomedical research. Although it is technically possible to genome-edit the chicken, its long generation time (6 months to sexual maturity) makes it an impractical lab model and has prevented it widespread use in research. The Japanese quail (Coturnix coturnix japonica) is an attractive alternative, very similar to the chicken, but with the decisive asset of a much shorter generation time (1.5 months). In recent years, transgenic quail lines have been described...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Genetics and Genomics Source Type: research

Distinct spatiotemporal mechanisms underlie extra-classical receptive field modulation in macaque V1 microcircuits
Complex scene perception depends upon the interaction between signals from the classical receptive field (CRF) and the extra-classical receptive field (eCRF) in primary visual cortex (V1) neurons. Although much is known about V1 eCRF properties, we do not yet know how the underlying mechanisms map onto the cortical microcircuit. We probed the spatio-temporal dynamics of eCRF modulation using a reverse correlation paradigm, and found three principal eCRF mechanisms: tuned-facilitation, untuned-suppression, and tuned-suppression. Each mechanism had a distinct timing and spatial profile. Laminar analysis showed that the timin...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Cortical bone maturation in mice requires SOCS3 suppression of gp130/STAT3 signalling in osteocytes
Bone strength is determined by its dense cortical shell, generated by unknown mechanisms. Here we use theDmp1Cre:Socs3f/f mouse, with delayed cortical bone consolidation, to characterise cortical maturation and identify control signals. We show that cortical maturation requires a reduction in cortical porosity, and a transition from low to high density bone, which continues even after cortical shape is established. Both processes were delayed inDmp1Cre:Socs3f/f mice. SOCS3 (suppressor of cytokine signalling 3) inhibits signalling by leptin, G-CSF, and IL-6 family cytokines (gp130). InDmp1Cre:Socs3f/f bone, STAT3 phosphoryl...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

The architecture of EMC reveals a path for membrane protein insertion
Approximately 25% of eukaryotic genes code for integral membrane proteins that are assembled at the endoplasmic reticulum. An abundant and widely conserved multi-protein complex termed EMC has been implicated in membrane protein biogenesis, but its mechanism of action is poorly understood. Here, we define the composition and architecture of human EMC using biochemical assays, crystallography of individual subunits, site-specific photocrosslinking, and cryo-EM reconstruction. Our results suggest that EMC's cytosolic domain contains a large, moderately hydrophobic vestibule that can bind a substrate's transmembrane domain (T...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Structural Biology and Molecular Biophysics Source Type: research

Remyelination alters the pattern of myelin in the cerebral cortex
Destruction of oligodendrocytes and myelin sheaths in cortical gray matter profoundly alters neural activity and is associated with cognitive disability in multiple sclerosis (MS). Myelin can be restored by regenerating oligodendrocytes from resident progenitors; however, it is not known whether regeneration restores the complex myelination patterns in cortical circuits. Here we performed time lapsein vivo two photon imaging in somatosensory cortex of adult mice to define the kinetics and specificity of myelin regeneration after acute oligodendrocyte ablation. These longitudinal studies revealed that the pattern of myelina...
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Structural insights into sodium transport by the oxaloacetate decarboxylase sodium pump
We present here structure of theSalmonella typhimurium OAD βγ sub-complex. The structure revealed that the β and γ subunits form a β3γ3 hetero-hexamer with extensive interactions between the subunits and shed light on the OAD holo-enzyme assembly. Structure-guided functional studies provided insights into the sodium binding sites in the β subunit and the coupling between carboxyl-biotin decarboxylation and sodium transport by the OAD β subunit. (Source: eLife)
Source: eLife - May 27, 2020 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Correction: Heterogeneity in surface sensing suggests a division of labor in < i > Pseudomonas aeruginosa < /i > populations
(Source: eLife)
Source: eLife - May 26, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Limitation of adipose tissue by the number of embryonic progenitor cells
Adipogenesis in adulthood replaces fat cells that turn over and can contribute to the development of obesity. However, the proliferative potential of adipocyte progenitors in vivo is unknown (Faust et al., 1976; Faust et al., 1977; Hirsch and Han, 1969; Johnson and Hirsch, 1972). We addressed this by injecting labeled wild-type embryonic stem cells into blastocysts derived from lipodystrophic A-ZIP transgenic mice, which have a genetic block in adipogenesis. In the resulting chimeric animals, wild-type ES cells are the only source of mature adipocytes. We found that when chimeric animals were fed a high-fat-diet, animals w...
Source: eLife - May 26, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

Estimates of the global burden of Japanese Encephalitis and the impact of vaccination from 2000-2015
In this study, we implemented a mathematical modelling method (catalytic model) combined with age-stratifed case data from our systematic review which can overcome some of these limitations. We estimate in 2015 JEV infections caused 100,308 JE cases (95%CI: 61,720 - 157,522) and 25,125 deaths (95%CI: 14,550 - 46,031) globally, and that between 2000 and 2015 307,774 JE cases (95%CI: 167,442- 509,583) were averted due to vaccination globally. Our results highlight areas that could have the greatest benefit from starting vaccination or from scaling up existing programs and will be of use to support local and international pol...
Source: eLife - May 26, 2020 Category: Biomedical Science Tags: Epidemiology and Global Health Source Type: research

Signaling diversity enabled by Rap1-regulated plasma membrane ERK with distinct temporal dynamics
A variety of different signals induce specific responses through a common, Extracellular-signal regulated kinase (ERK)-dependent cascade. It has been suggested that signaling specificity can be achieved through precise temporal regulation of ERK activity. Given the wide distrubtion of ERK susbtrates across different subcellular compartments, it is important to understand how ERK activity is temporally regulated at specific subcellular locations. To address this question, we have expanded the toolbox of F örster Resonance Energy Transfer (FRET)-based ERK biosensors by creating a series of improved biosensors targeted t...
Source: eLife - May 26, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

HIV efficiently infects T cells from the endometrium and remodels them to promote systemic viral spread
The female reproductive tract (FRT) is the most common site of infection during HIV transmission to women, but viral remodeling complicates characterization of cells targeted for infection. Here, we report extensive phenotypic analyses of HIV-infected endometrial cells by CyTOF, and use a ‘nearest neighbor’ bioinformatics approach to trace cells to their original pre-infection phenotypes. Like in blood, HIV preferentially targets memory CD4+ T cells in the endometrium, but these cells exhibit unique phenotypes and sustain much higher levels of infection. Genital cell remodeling b y HIV includes downregulating T...
Source: eLife - May 26, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Paranoia as a deficit in non-social belief updating
Paranoia is the belief that harm is intended by others. It may arise from selective pressures to infer and avoid social threats, particularly in ambiguous or changing circumstances. We propose that uncertainty may be sufficient to elicit learning differences in paranoid individuals, without social threat. We used reversal learning behavior and computational modeling to estimate belief updating across individuals with and without mental illness, online participants, and rats chronically exposed to methamphetamine, an elicitor of paranoia in humans. Paranoia is associated with a stronger prior on volatility, accompanied by e...
Source: eLife - May 26, 2020 Category: Biomedical Science Tags: Human Biology and Medicine Neuroscience Source Type: research

Regulation of nerve growth and patterning by cell surface protein disulphide isomerase
This study shows that protein disulphide isomerase provides a key component of these barriers, mediating contact repulsion at the cell surface in chick half-somites. Repulsion is reduced bothin vivoandin vitro by a range of methods that inhibit enzyme activity. The activity is critical in initiating a nitric oxide/S-nitrosylation-dependent signal transduction pathway that regulates the growth cone cytoskeleton. Rat forebrain grey matter extracts contain a similar activity, and the enzyme is expressed at the surface of cultured human astrocytic cells and rat cortical astrocytes. We suggest this system is co-opted in the bra...
Source: eLife - May 26, 2020 Category: Biomedical Science Tags: Developmental Biology Neuroscience Source Type: research