Molecular basis for substrate specificity of the Phactr1/PP1 phosphatase holoenzyme
PPP-family phosphatases such as PP1 have little intrinsic specificity. Cofactors can target PP1 to substrates or subcellular locations, but it remains unclear how they might confer sequence-specificity on PP1. The cytoskeletal regulator Phactr1 is a neuronally-enriched PP1 cofactor that is controlled by G-actin. Structural analysis showed that Phactr1 binding remodels PP1's hydrophobic groove, creating a new composite surface adjacent to the catalytic site. Using phosphoproteomics, we identified mouse fibroblast and neuronal Phactr1/PP1 substrates, which include cytoskeletal components and regulators. We determined high-re...
Source: eLife - September 25, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Structural Biology and Molecular Biophysics Source Type: research

Symbiont-mediated cytoplasmic incompatibility: what have we learned in 50 years?
Cytoplasmic incompatibility (CI) is the most common symbiont-induced reproductive manipulation. Specifically, symbiont-induced sperm modifications cause catastrophic mitotic defects in the fertilized embryo and ensuing lethality in crosses between symbiotic males and either aposymbiotic females or females harboring a different symbiont strain. However, if the female carries the same symbiont strain, then embryos develop properly, thereby imparting a relative fitness benefit to symbiont-transmitting mothers. Thus, CI drives maternally-transmitted bacteria to high frequencies in arthropods worldwide. In the past two decades,...
Source: eLife - September 25, 2020 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Phosphatidylinositol 3-phosphate and Hsp70 protect < i > Plasmodium falciparum < /i > from heat-induced cell death
Phosphatidylinositol 3-phosphate (PI(3)P) levels inPlasmodium falciparum correlate with tolerance to cellular stresses caused by artemisinin and environmental factors. However, PI(3)P function during thePlasmodium stress response was unknown. Here, we used PI3K inhibitors and antimalarial agents to examine the importance of PI(3)P under thermal conditions recapitulating malarial fever. Live cell microscopy using chemical and genetic reporters revealed that PI(3)P stabilizes the digestive vacuole (DV) under heat stress. We demonstrate that heat-induced DV destabilization in PI(3)P-deficientP. falciparum precedes cell death ...
Source: eLife - September 25, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Microbiology and Infectious Disease Source Type: research

Photosynthesis without β-carotene
Carotenoids are essential in oxygenic photosynthesis: they stabilize the pigment-protein complexes, are active in harvesting sunlight and in photoprotection. In plants, they are present as carotenes and their oxygenated derivatives, xanthophylls. While mutant plants lacking xanthophylls are capable of photoautotrophic growth, no plants without carotenes in their photosystems have been reported so far, which has led to the common opinion that carotenes are essential for photosynthesis. Here, we report the first plant that grows photoautotrophically in the absence of carotenes: a tobacco plant containing only the xanthophyll...
Source: eLife - September 25, 2020 Category: Biomedical Science Tags: Plant Biology Source Type: research

POMK regulates dystroglycan function via LARGE-mediated elongation of matriglycan
Matriglycan [-GlcA- β1,3-Xyl-α1,3-]n serves as a scaffold in many tissues for extracellular matrix proteins containing laminin-G domains including laminin, agrin, and perlecan. Like-acetylglucosaminyltransferase-1 (LARGE1) synthesizes and extends matriglycan on α-dystroglycan (α-DG)during skeletal muscle differentiation and regeneration; however, the mechanisms which regulate matriglycan elongation are unknown. Here, we show thatProtein O-Mannose Kinase (POMK), which phosphorylates mannose of core M3 (GalNac- β1,3-GlcNac-β1,4-Man) preceding matriglycan synthesis, is required for LARGE1-medi...
Source: eLife - September 25, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Source Type: research

A multi-layered and dynamic apical extracellular matrix shapes the vulva lumen in < i > Caenorhabditis elegans < /i >
Biological tubes must develop and maintain their proper diameter in order to transport materials efficiently. These tubes are molded and protected in part by apical extracellular matrices (aECMs) that line their lumens. Despite their importance, aECMs are difficult to imagein vivoand therefore poorly understood.TheC. elegans vulva has been a paradigm for understanding many aspects of organogenesis. Here we describe the vulva luminal matrix, which contains chondroitin proteoglycans, Zona Pellucida (ZP) domain proteins, and other glycoproteins and lipid transporters related to those in mammals. Confocal and transmission elec...
Source: eLife - September 25, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Hedgehog signaling is required for endomesodermal patterning and germ cell development in the sea anemone < i > Nematostella vectensis < /i >
Two distinct mechanisms for primordial germ cell (PGC) specification are observed within Bilatera: early determination by maternal factors or late induction by zygotic cues. Here we investigate the molecular basis for PGC specification inNematostella, a representative pre-bilaterian animal where PGCs arise as paired endomesodermal cell clusters during early development. We first present evidence that the putative PGCs delaminate from the endomesoderm upon feeding, migrate into the gonad primordia, and mature into germ cells. We then show that the PGC clusters arise at the interface betweenhedgehog1 andpatched domains in th...
Source: eLife - September 24, 2020 Category: Biomedical Science Tags: Developmental Biology Evolutionary Biology Source Type: research

MondoA regulates gene expression in cholesterol biosynthesis-associated pathways required for zebrafish epiboly
The glucose-sensing Mondo pathway regulates expression of metabolic genes in mammals. Here, we characterized its function in the zebrafish and revealed an unexpected role of this pathway in vertebrate embryonic development. We showed that knockdown ofmondoa impaired the early morphogenetic movement of epiboly in zebrafish embryos and caused microtubule defects. Expression of genes in the terpenoid backbone and sterol biosynthesis pathways upstream of pregnenolone synthesis was coordinately downregulated in these embryos, including the most downregulated genensdhl. Loss of Nsdhl function likewise impaired epiboly, similar t...
Source: eLife - September 24, 2020 Category: Biomedical Science Tags: Developmental Biology Genetics and Genomics Source Type: research

Correction: A nuclear role for the DEAD-box protein Dbp5 in tRNA export
(Source: eLife)
Source: eLife - September 24, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Source Type: research

Molecular mechanism for direct actin force-sensing by α-catenin
The actin cytoskeleton mediates mechanical coupling between cells and their tissue microenvironments. The architecture and composition of actin networks are modulated by force, but it is unclear how interactions between actin filaments (F-actin) and associated proteins are mechanically regulated. Here, we employ both optical trapping and biochemical reconstitution with myosin motor proteins to show single piconewton forces applied solely to F-actin enhance binding by the human version of the essential cell-cell adhesion protein αE-catenin, but not its homolog vinculin. Cryo-electron microscopy structures of both prot...
Source: eLife - September 24, 2020 Category: Biomedical Science Tags: Cell Biology Structural Biology and Molecular Biophysics Source Type: research

Light-Regulated allosteric switch enables temporal and subcellular control of enzyme activity
Engineered allosteric regulation of protein activity provides significant advantages for the development of robust and broadly applicable tools. However, the application of allosteric switches in optogenetics has been scarce and suffers from critical limitations. Here, we report an optogenetic approach that utilizes an engineered Light-Regulated (LightR) allosteric switch module to achieve tight spatiotemporal control of enzymatic activity. Using the tyrosine kinase Src as a model, we demonstrate efficient regulation of the kinase and identify temporally distinct signaling responses ranging from seconds to minutes. LightR-...
Source: eLife - September 23, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

Stoichiometric interactions explain spindle dynamics and scaling across 100 million years of nematode evolution
The spindle shows remarkable diversity, and changes in an integrated fashion, as cells vary over evolution. Here, we provide a mechanistic explanation for variations in the first mitotic spindle in nematodes. We used a combination of quantitative genetics and biophysics to rule out broad classes of models of the regulation of spindle length and dynamics, and to establish the importance of a balance of cortical pulling forces acting in different directions. These experiments led us to construct a model of cortical pulling forces in which the stoichiometric interactions of microtubules and force generators (each force genera...
Source: eLife - September 23, 2020 Category: Biomedical Science Tags: Cell Biology Physics of Living Systems Source Type: research

Live imaging of hair bundle polarity acquisition demonstrates a critical timeline for transcription factor Emx2
The asymmetric hair bundle on top of hair cells (HCs), comprises a kinocilium and stereocilia staircase, dictates HC's directional sensitivity. The mother centriole (MC) forms the base of the kinocilium, where stereocilia are subsequently built next to it. Previously we showed that transcription factor Emx2 reverses hair bundle orientation and its expression in the mouse vestibular utricle is restricted, resulting in two regions of opposite bundle orientation (Jiang et al, 2017). Here, we investigated establishment of opposite bundle orientation in embryonic utricles by live-imaging GFP-labeled centrioles in HCs. The daugh...
Source: eLife - September 23, 2020 Category: Biomedical Science Tags: Cell Biology Developmental Biology Source Type: research

Ribosome recycling is not critical for translational coupling in < i > E. coli < /i >
We used ribosome profiling to characterize the biological role of ribosome recycling factor (RRF) inE. coli. As expected, RRF depletion leads to enrichment of post-termination 70S complexes in 3'-UTRs. We also observe that elongating ribosomes are unable to complete translation because they are blocked by non-recycled ribosomes at stop codons. Previous studies have suggested a role for recycling in translational coupling within operons; if a ribosome remains bound to an mRNA after termination, it may re-initiate downstream. We found, however, that RRF depletion did not significantly affect coupling efficiency in reporter a...
Source: eLife - September 23, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Source Type: research

Unbiased homeologous recombination during pneumococcal transformation allows for multiple chromosomal integration events
The spread of antimicrobial resistance and vaccine escape in the human pathogenStreptococcus pneumoniae can be largely attributed to competence-induced transformation. Here, we studied this process at the single-cell level. We show that within isogenic populations, all cells become naturally competent and bind exogenous DNA. We find that transformation is highly efficient and that the chromosomal location of the integration site or whether the transformed gene is encoded on the leading or lagging strand has limited influence on recombination efficiency. Indeed, we have observed multiple recombination events in single recip...
Source: eLife - September 23, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Why scientific societies should involve more early-career researchers
This article looks at the level of influence ECRs have in 20 scientific societies based in the US and UK, and provides guidelines on how societies can successfully include ECRs in leadership roles. (Source: eLife)
Source: eLife - September 23, 2020 Category: Biomedical Science Source Type: research

Bimodal function of chromatin remodeler < i > Hmga1 < /i > in neural crest induction and Wnt-dependent emigration
During gastrulation, neural crest cells are specified at the neural plate border, as characterized byPax7 expression. Using single-cell RNA sequencing coupled with high resolutionin situ hybridization to identify novel transcriptional regulators, we show that chromatin remodelerHmga1 is highly expressed prior to specification and maintained in migrating chick neural crest cells. Temporally-controlled CRISPR-Cas9-mediated knockouts uncovered two distinct functions ofHmga1 in neural crest development. At the neural plate border,Hmga1 regulates Pax7-dependent neural crest lineage specification. At premigratory stages, a secon...
Source: eLife - September 23, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Alstrom syndrome gene is a stem cell-specific regulator of centriole duplication in the < i > Drosophila < /i > testis
Asymmetrically dividing stem cells often show asymmetric behavior of the mother versus daughter centrosomes, whereby the self-renewing stem cell selectively inherits the mother or daughter centrosome. Although the asymmetric centrosome behavior is widely conserved, its biological significance remains largely unclear. Here we show that Alms1a, aDrosophila homolog of the human ciliopathy gene Alstrom syndrome, is enriched on the mother centrosome inDrosophila male germline stem cells (GSCs). Depletion ofalms1a in GSCs, but not in differentiating germ cells, results in rapid loss of centrosomes due to a failure in daughter ce...
Source: eLife - September 23, 2020 Category: Biomedical Science Tags: Cell Biology Developmental Biology Source Type: research

Spectral clustering of risk score trajectories stratifies sepsis patients by clinical outcome and interventions received
Sepsis is not a monolithic disease, but a loose collection of symptoms with diverse outcomes. Thus, stratification and subtyping of sepsis patients is of great importance. We examine the temporal evolution of patient state using our previously-published method for computing risk of transition from sepsis into septic shock. Risk trajectories diverge into four clusters following early prediction of septic shock, stratifying by outcome: the highest-risk and lowest-risk groups have a 76.5% and 10.4% prevalence of septic shock, and 43% and 18% mortality, respectively. These clusters differ also in treatments received and median...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Computational and Systems Biology Source Type: research

Ribosomal profiling during prion disease uncovers progressive translational derangement in glia but not in neurons
Prion diseases are caused by PrPSc, a self-replicating pathologically misfolded protein that exerts toxicity predominantly in the brain. The administration of PrPSc causes a robust, reproducible and specific disease manifestation. Here we have applied a combination of translating ribosome affinity purification and ribosome profiling to identify biologically relevant prion-induced changes during disease progression in a cell-type specific and genome-wide manner. Terminally diseased mice with severe neurological symptoms showed extensive alterations in astrocytes and microglia. Surprisingly, we detected only minor changes in...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Integrase-RNA interactions underscore the critical role of integrase in HIV-1 virion morphogenesis
A number of human immunodeficiency virus 1 integrase (IN) alterations, referred to as class II substitutions, exhibit pleotropic effects during virus replication. However, the underlying mechanism for the class II phenotype is not known. Here we demonstrate that all tested class II IN substitutions compromised IN-RNA binding in virions by one of three distinct mechanisms: i) markedly reducing IN levels thus precluding formation of IN complexes with viral RNA; ii) adversely affecting functional IN multimerization and consequently impairing IN binding to viral RNA; iii) directly compromising IN-RNA interactions without subst...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Nutrient status shapes selfish mitochondrial genome dynamics across different levels of selection
Cooperation and cheating are widespread evolutionary strategies. While cheating confers an advantage to individual entities within a group, competition between groups favors cooperation. Selfish or cheater mitochondrial DNA (mtDNA) proliferates within hosts while being selected against at the level of host fitness. How does environment shape cheater dynamics across different selection levels? Focusing on food availability, we address this question using heteroplasmicCaenorhabditis elegans. We find that the proliferation of selfish mtDNA within hosts depends on nutrient status stimulating mtDNA biogenesis in the developing ...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Homeostatic plasticity in the retina is associated with maintenance of night vision during retinal degenerative disease
Neuronal plasticity of the inner retina has been observed in response to photoreceptor degeneration. Typically, this phenomenon has been considered maladaptive and may preclude vision restoration in the blind. However, several recent studies utilizing triggered photoreceptor ablation have shown adaptive responses in bipolar cells expected to support normal vision. Whether such homeostatic plasticity occurs during progressive photoreceptor degenerative disease to help maintain normal visual behavior is unknown. We addressed this issue in an established mouse model of Retinitis Pigmentosa caused by the P23H mutation in rhodo...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

BiteOscope, an open platform to study mosquito biting behavior
Female mosquitoes need a blood meal to reproduce, and in obtaining this essential nutrient they transmit deadly pathogens. Although crucial for the spread of mosquito-borne diseases, blood feeding remains poorly understood due to technological limitations. Indeed, studies often expose human subjects to assess biting behavior. Here, we present the biteOscope, a device that attracts mosquitoes to a host mimic which they bite to obtain an artificial blood meal. The host mimic is transparent, allowing high-resolution imaging of the feeding mosquito. Using machine learning we extract detailed behavioral statistics describing th...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Ecology Neuroscience Source Type: research

Evolution of island lizards remains a mystery
Lizards that live in the Greater Antilles exploit a large range of skeletal variations to adapt to similar habitats, in defiance of the theory of plasticity-led evolution. (Source: eLife)
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Evolutionary Biology Source Type: research

Host-induced spermidine production in motile < i > Pseudomonas aeruginosa < /i > triggers phagocytic uptake
Exploring the complexity of host-pathogen communication is vital to understand why microbes persist within a host, while others are cleared. Here, we employed a Dual-sequencing approach to unravel conversational turn-taking of dynamic host-pathogen communications. We demonstrate that upon hitting a host cell, motilePseudomonas aeruginosa induce a specific gene expression program. This results in the expression of spermidine on the surface, which specifically activates the PIP3-pathway to induce phagocytic uptake into primary or immortalized murine cells. Non-motile bacteria are more immunogenic due to a lower expression of...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Tuning movement for sensing in an uncertain world
While animals track or search for targets, sensory organs make small unexplained movements on top of the primary task-related motions. While multiple theories for these movements exist —in that they support infotaxis, gain adaptation, spectral whitening, and high-pass filtering—predicted trajectories show poor fit to measured trajectories. We propose a new theory for these movements called energy-constrained proportional betting, where the probability of moving to a location i s proportional to an expectation of how informative it will be balanced against the movement’s predicted energetic cost. Trajector...
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Computational and Systems Biology Neuroscience Source Type: research

The perils of cheating
Experiments on mitochondrial DNA in worms highlight that cheating does not always pay off. (Source: eLife)
Source: eLife - September 22, 2020 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Genetic mapping of etiologic brain cell types for obesity
The underlying cell types mediating predisposition to obesity remain largely obscure. Here, we integrated recently published single-cell RNA-sequencing (scRNA-seq) data from 727 peripheral and nervous system cell types spanning 17 mouse organs with body mass index (BMI) genome-wide association study (GWAS) data from>457,000 individuals. Developing a novel strategy for integrating scRNA-seq data with GWAS data, we identified 26, exclusively neuronal, cell types from the hypothalamus, subthalamus, midbrain, hippocampus, thalamus, cortex, pons, medulla, pallidum that were significantly enriched for BMI heritability (p
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Computational and Systems Biology Genetics and Genomics Source Type: research

Ubiquitin-interacting motifs of ataxin-3 regulate its polyglutamine toxicity through Hsc70-4-dependent aggregation
Spinocerebellar ataxia type 3 (SCA3) belongs to the family of polyglutamine neurodegenerations. Each disorder stems from the abnormal lengthening of a glutamine repeat in a different protein. Although caused by a similar mutation, polyglutamine disorders are distinct, implicating non-polyglutamine regions of disease proteins as regulators of pathogenesis. SCA3 is caused by polyglutamine expansion in ataxin-3. To determine the role of ataxin-3 ’s non-polyglutamine domains in disease, we utilized a new, allelic series ofDrosophila melanogaster. We found that ataxin-3 pathogenicity is saliently controlled by polyglutami...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Cell Biology Neuroscience Source Type: research

Genome-wide alterations of uracil distribution patterns in human DNA upon chemotherapeutic treatments
Numerous anti-cancer drugs perturb thymidylate biosynthesis and lead to genomic uracil incorporation contributing to their antiproliferative effect. Still, it is not yet characterized if uracil incorporations have any positional preference. Here, we aimed to uncover genome-wide alterations in uracil pattern upon drug treatments in human cancer cell line models derived from HCT116. We developed a straightforward U-DNA sequencing method (U-DNA-Seq) that was combined with in situ super-resolution imaging. Using a novel robust analysis pipeline, we found broad regions with elevated probability of uracil occurrence both in trea...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Source Type: research

Therapeutic effects of anodal transcranial direct current stimulation in a rat model of ADHD
Most therapeutic candidates for treating attention deficit hyperactivity disorder (ADHD) have focused on modulating the dopaminergic neurotransmission system with neurotrophic factors. Regulation of this system by transcranial direct current stimulation (tDCS) could contribute to the recovery of cognitive symptoms observed in patients with ADHD. Here, male spontaneously hypertensive (SHR) rats were subjected to consecutive high-definition tDCS (HD-tDCS) (20 min, 50 μA, current density 63.7 A/m2, charge density 76.4 kC/m2) over the prefrontal cortex. This treatment alleviated cognitive deficits, with an increase in tyros...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Localized inhibition in the Drosophila mushroom body
Many neurons show compartmentalized activity, in which activity does not spread readily across the cell, allowing input and output to occur locally. However, the functional implications of compartmentalized activity for the wider neural circuit are often unclear. We addressed this problem in theDrosophila mushroom body, whose principal neurons, Kenyon cells, receive feedback inhibition from a non-spiking interneuron called APL. We used local stimulation and volumetric calcium imaging to show that APL inhibits Kenyon cells ’ dendrites and axons, and that both activity in APL and APL’s inhibitory effect on Kenyon...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

The effect of hybridization on transposable element accumulation in an undomesticated fungal species
Transposable elements (TEs) are mobile genetic elements that can profoundly impact the evolution of genomes and species. A long-standing hypothesis suggests that hybridization could deregulate TEs and trigger their accumulation, although it received mixed support from studies in plants and animals. Here, we tested this hypothesis in fungi using incipient species of the undomesticated yeastSaccharomyces paradoxus. Population genomic data revealed no signature of higher transposition in natural hybrids. As we could not rule out the elimination of past transposition increase signatures by natural selection, we performed a lab...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Deciphering the regulatory genome of < i > Escherichia coli < /i > , one hundred promoters at a time
Advances in DNA sequencing have revolutionized our ability to read genomes. However, even in the most well-studied of organisms, the bacteriumEscherichia coli, for ≈ 65% of promoters we remain ignorant of their regulation. Until we crack this regulatory Rosetta Stone, efforts to read and write genomes will remain haphazard. We introduce a new method, Reg-Seq, that links massively-parallel reporter assays with mass spectrometry to produce a base pair resoluti on dissection of more than 100E. colipromoters in 12 growth conditions. We demonstrate that the method recapitulates known regulatory information. Then, we exami...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Physics of Living Systems Source Type: research

AANAT1 functions in astrocytes to regulate sleep homeostasis
How the brain controls the need and acquisition of recovery sleep after prolonged wakefulness is an important issue in sleep research. The monoamines serotonin and dopamine are key regulators of sleep in mammals and inDrosophila. We found that the enzyme arylalkylamine N-acetyltransferase 1 (AANAT1) is expressed byDrosophila astrocytes and specific subsets of neurons in the adult brain. AANAT1 acetylates monoamines and inactivates them, and we found that AANAT1 limited the accumulation of serotonin and dopamine in the brain upon sleep deprivation. Loss of AANAT1 from astrocytes, but not from neurons, caused flies to increa...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Site-specific effects of neurosteroids on GABA < sub > A < /sub > receptor activation and desensitization
This study examines how site-specific binding to three identified neurosteroid binding sites in the α1β3 GABAA receptor (GABAAR) contributes to neurosteroid allosteric modulation. We found that the potentiating neurosteroid, allopregnanolone, but not its inhibitory 3 β-epimer epi-allopregnanolone, binds to the canonical β3(+) –α1(-) intersubunit site that mediates receptor activation by neurosteroids. In contrast, both allopregnanolone and epi-allopregnanolone bind to intrasubunit sites in the β3 subunit, promoting receptor desensitization and the α1 subunit promoting effects tha...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Chronic postnatal chemogenetic activation of forebrain excitatory neurons evokes persistent changes in mood behavior
Early adversity is a risk factor for the development of adult psychopathology. Common across multiple rodent models of early adversity is increased signaling via forebrain Gq-coupled neurotransmitter receptors. We addressed whether enhanced Gq-mediated signaling in forebrain excitatory neurons during postnatal life can evoke persistent mood-related behavioral changes. Excitatory hM3Dq DREADD-mediated chemogenetic activation of forebrain excitatory neurons during postnatal life (P2-14), but not in juvenile or adult windows, increased anxiety-, despair-, and schizophrenia-like behavior in adulthood. This was accompanied by a...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

< i > PTPRG < /i > is an ischemia risk locus essential for HCO < sub > 3 < /sub > < sup > - < /sup > -dependent regulation of endothelial function and tissue perfusion
Acid-base conditions modify artery tone and tissue perfusion but the involved vascular sensing mechanisms and disease consequences remain unclear. We experimentally investigated transgenic mice and performed genetic studies in a UK-based human cohort. We show that endothelial cells express the putative HCO3–-sensor receptor-type tyrosine-protein phosphatase RPTPg, which enhances endothelial intracellular Ca2+-responses in resistance arteries and facilitates endothelium-dependent vasorelaxation only when CO2/HCO3– is present. Consistent with waning RPTPg-dependent vasorelaxation at low [HCO3–], RPTPg limit...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Genetics and Genomics Medicine Source Type: research

Dynamic encoding of social threat and spatial context in the hypothalamus
Social aggression and avoidance are defensive behaviors expressed by territorial animals in a manner appropriate to spatial context and experience. The ventromedial hypothalamus controls both social aggression and avoidance, suggesting that it may encode a general internal state of threat modulated by space and experience. Here, we show that neurons in the mouse ventromedial hypothalamus are activated both by the presence of a social threat as well as by a chamber where social defeat previously occurred. Moreover, under conditions where the animal could move freely between a home and defeat chamber, firing activity emerged...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Apelin signaling drives vascular endothelial cells towards a pro-angiogenic state
To form new blood vessels (angiogenesis), endothelial cells (ECs) must be activated and acquire highly migratory and proliferative phenotypes. However, the molecular mechanisms that govern these processes are incompletely understood. Here, we show that Apelin signaling functions to drive ECs into such an angiogenic state. Zebrafish lacking Apelin signaling exhibit defects in endothelial tip cell morphology and sprouting. Using transplantation experiments, we find that in mosaic vessels, wild-type ECs leave the dorsal aorta (DA) and form new vessels while neighboring ECs defective in Apelin signaling remain in the DA. Mecha...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Serine phosphorylation regulates the P-type potassium pump KdpFABC
KdpFABC is an ATP-dependent K+ pump that ensures bacterial survival in K+-deficient environments. Whereas transcriptional activation of kdpFABC expression is well studied, a mechanism for down regulation when K+ levels are restored has not been described. Here we show that KdpFABC is inhibited when cells return to a K+-rich environment. The mechanism of inhibition involves phosphorylation of Ser162 on KdpB, which can be reversed in vitro by treatment with serine phosphatase. Mutating Ser162 to Alanine produces constitutive activity, whereas the phosphomimetic Ser162Asp mutation inactivates the pump. Analyses of the transpo...
Source: eLife - September 21, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Structural Biology and Molecular Biophysics Source Type: research

WDR90 is a centriolar microtubule wall protein important for centriole architecture integrity
Centrioles are characterized by a nine-fold arrangement of microtubule triplets held together by an inner protein scaffold. These structurally robust organelles experience strenuous cellular processes such as cell division or ciliary beating while performing their function. However, the molecular mechanisms underlying the stability of microtubule triplets, as well as centriole architectural integrity remain poorly understood. Here, using ultrastructure expansion microscopy for nanoscale protein mapping, we reveal that POC16 and its human homolog WDR90 are components of the microtubule wall along the central core region of ...
Source: eLife - September 18, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

Cell-cycle-gated feedback control mediates desensitization to interferon stimulation
In this study, we combine microfluidics, time-lapse microscopy, and computational modeling to investigate how the type I interferon (IFN)-responsive regulatory network operates in single human cells to process repetitive IFN stimulation. We found that IFN- α pretreatments lead to opposite effects, priming versus desensitization, depending on input durations. These effects are governed by a regulatory network composed of a fast-acting positive feedback loop and a delayed negative feedback loop, mediated by upregulation of ubiquitin-specific peptidase 18 (USP18). We further revealed that USP18 upregulation can only be ...
Source: eLife - September 18, 2020 Category: Biomedical Science Tags: Computational and Systems Biology Source Type: research

External location of touch is constructed post-hoc based on limb choice
When humans indicate on which hand a tactile stimulus occurred, they often err when their hands are crossed. This finding seemingly supports the view that the automatically determined touch location in external space affects limb assignment: the crossed right hand is localized in left space, and this conflict presumably provokes hand assignment errors. Here, participants judged on which hand the first of two stimuli, presented during a bimanual movement, had occurred, and then indicated its external location by a reach-to-point movement. When participants incorrectly chose the hand stimulated second, they pointed to where ...
Source: eLife - September 18, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

The transcriptomic response of cells to a drug combination is more than the sum of the responses to the monotherapies
Our ability to discover effective drug combinations is limited, in part by insufficient understanding of how the transcriptional response of two monotherapies results in that of their combination. We analyzed matched time course RNAseq profiling of cells treated with single drugs and their combinations and found that the transcriptional signature of the synergistic combination was unique relative to that of either constituent monotherapy. The sequential activation of transcription factors in time in the gene regulatory network was implicated. The nature of this transcriptional cascade suggests that drug synergy may ensue w...
Source: eLife - September 18, 2020 Category: Biomedical Science Tags: Cell Biology Computational and Systems Biology Source Type: research

Acetylcholine is released in the basolateral amygdala in response to predictors of reward and enhances learning of cue-reward contingency
The basolateral amygdala (BLA) is critical for associating initially neutral cues with appetitive and aversive stimuli and receives dense neuromodulatory acetylcholine (ACh) projections. We measured BLA ACh signaling and activity of neurons expressing CaMKII α (a marker for glutamatergic principal cells) in mice during cue-reward learning using a fluorescent ACh sensor and calcium indicators. We found that ACh levels and nucleus basalis of Meynert (NBM) cholinergic terminal activity in the BLA (NBM-BLA) increased sharply in response to reward-related e vents and shifted as mice learned the cue-reward contingency. BLA...
Source: eLife - September 18, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

A novel DNA primase-helicase pair encoded by SCC < i > mec < /i > elements
Mobile genetic elements (MGEs) are a rich source of new enzymes, and conversely, understanding the activities of MGE-encoded proteins can elucidate MGE function. Here we biochemically characterize 3 proteins encoded by a conserved operon carried by the Staphylococcal Cassette Chromosome (SCCmec), an MGE that confers methicillin resistance toStaphylococcus aureus, creating MRSA strains. The first of these proteins, CCPol, is an active A-family DNA polymerase. The middle protein, MP, binds tightly to CCPol and confers upon it the ability to synthesize DNA primersde novo. The CCPol-MP complex is therefore a unique primase-pol...
Source: eLife - September 18, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Source Type: research

Topological constraints in early multicellularity favor reproductive division of labor
Reproductive division of labor (e.g., germ-soma specialization) is a hallmark of the evolution of multicellularity, signifying the emergence of a new type of individual and facilitating the evolution of increased organismal complexity. A large body of work from evolutionary biology, economics, and ecology has shown that specialization is beneficial when further division of labor produces an accelerating increase in absolute productivity (i.e., productivity is a convex function of specialization). Here we show that reproductive specialization is qualitatively different from classical models of resource sharing, and can evol...
Source: eLife - September 17, 2020 Category: Biomedical Science Tags: Evolutionary Biology Source Type: research

A whole-brain connectivity map of mouse insular cortex
The insular cortex (IC) plays key roles in emotional and regulatory brain functions and is affected across psychiatric diseases. However, the brain-wide connections of the mouse IC have not been comprehensively mapped. Here we traced the whole-brain inputs and outputs of the mouse IC across its rostro-caudal extent. We employed cell-type specific monosynaptic rabies virus tracings to characterize afferent connections onto either excitatory or inhibitory IC neurons, and adeno-associated viral tracings to label excitatory efferent axons. While the connectivity between the IC and other cortical regions was highly bidirectiona...
Source: eLife - September 17, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research