Neural dynamics of perceptual inference and its reversal during imagery
After the presentation of a visual stimulus, neural processing cascades from low-level sensory areas to increasingly abstract representations in higher-level areas. It is often hypothesised that a reversal in neural processing underlies the generation of mental images as abstract representations are used to construct sensory representations in the absence of sensory input. According to predictive processing theories, such reversed processing also plays a central role in later stages of perception. Direct experimental evidence of reversals in neural information flow has been missing. Here, we used a combination of machine l...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Different theta frameworks coexist in the rat hippocampus and are coordinated during memory-guided and novelty tasks
Hippocampal firing is organized in theta sequences controlled by internal memory processes and by external sensory cues, but how these computations are coordinated is not fully understood. Although theta activity is commonly studied as a unique coherent oscillation, it is the result of complex interactions between different rhythm generators. Here, by separating hippocampal theta activity in three different current generators, we found epochs with variable theta frequency and phase coupling, suggesting flexible interactions between theta generators. We found that epochs of highly synchronized theta rhythmicity preferential...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Stochastic logistic models reproduce experimental time series of microbial communities
We analyze properties of experimental microbial time series, from plankton and the human microbiome, and investigate whether stochastic generalized Lotka-Volterra models could reproduce those properties. We show that this is the case when the noise term is large and a linear function of the species abundance, while the strength of the self-interactions varies over multiple orders of magnitude. We stress the fact that all the observed stochastic properties can be obtained from a logistic model, i.e. without interactions, even the niche character of the experimental time series. Linear noise is associated with growth rate st...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Computational and Systems Biology Source Type: research

S-phase-independent silencing establishment in < i > Saccharomyces cerevisiae < /i >
The establishment of silent chromatin, a heterochromatin-like structure atHMLandHMR inSaccharomyces cerevisiae, depends on progression through S phase of the cell cycle, but the molecular nature of this requirement has remained elusive despite intensive study. Using high-resolution chromatin immunoprecipitation and single-molecule RNA analysis, we found that silencing establishment proceeded via gradual repression of transcription in individual cells over several cell cycles, and that the cell-cycle-regulated step was downstream of Sir protein recruitment. In contrast to prior results,HML andHMR had identical cell-cycle re...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Genetics and Genomics Source Type: research

Human DECR1 is an androgen-repressed survival factor that regulates PUFA oxidation to protect prostate tumor cells from ferroptosis
Fatty acid β-oxidation (FAO) is the main bioenergetic pathway in human prostate cancer (PCa) and a promising novel therapeutic vulnerability. Here we demonstrate therapeutic efficacy of targeting FAO in clinical prostate tumors culturedex vivo,and identify DECR1,encoding the rate-limiting enzyme for oxidation of polyunsaturated fatty acids (PUFAs), as robustly overexpressed in PCa tissues and associated with shorter relapse-free survival.DECR1 is a negatively-regulated androgen receptor (AR) target gene and, therefore, may promote PCa cell survival and resistance to AR targeting therapeutics. DECR1 knockdown selective...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Cancer Biology Source Type: research

DAZL mediates a broad translational program regulating expansion and differentiation of spermatogonial progenitors
Fertility across metazoa requires the germline-specific DAZ family of RNA-binding proteins. Here we examine whether DAZL directly regulates progenitor spermatogonia using a conditional genetic mouse model andin vivo biochemical approaches combined with chemical synchronization of spermatogenesis. We find that the absence ofDazlimpairs both expansion and differentiation of the spermatogonial progenitor population. In undifferentiated spermatogonia, DAZL binds the 3' UTRs of ~2,500 protein-coding genes. Some targets are known regulators of spermatogonial proliferation and differentiation while others are broadly expressed, d...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Universality of clonal dynamics poses fundamental limits to identify stem cell self-renewal strategies
How adult stem cells maintain self-renewing tissues is in vivo commonly assessed by analysing clonal data from cell lineage tracing assays. To identify strategies of stem cell self-renewal requires that different models of stem cell fate choice predict sufficiently different clonal statistics. Here we show that models of cell fate choice can, in homeostatic tissues, be categorized by exactly two 'universality classes', whereby models of the same class predict, under asymptotic conditions, the same clonal statistics. Those classes relate to generalizations of the canonical asymmetric vs. symmetric stem cell self-renewal str...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Computational and Systems Biology Developmental Biology Source Type: research

Alterations in the intrinsic properties of striatal cholinergic interneurons after dopamine lesion and chronic L-DOPA
Changes in striatal cholinergic interneuron (ChI) activity are thought to contribute to Parkinson's disease pathophysiology and dyskinesia from chronic L-3,4-dihydroxyphenylalanine (L-DOPA) treatment, but the physiological basis of these changes is unknown. We find that dopamine lesion decreases the spontaneous firing rate of ChIs, whereas chronic treatment with L-DOPA of lesioned mice increases baseline ChI firing rates to levels beyond normal activity. The effect of dopamine loss on ChIs was due to decreased currents of both hyperpolarization-activated cyclic nucleotide-gated (HCN) and small conductance calcium-activated...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

IL18 signaling promotes homing of mature Tregs into the thymus
Foxp3+ regulatory T cells (Tregs) are potent suppressor cells, essential for the maintenance of immune homeostasis. Most Tregs develop in the thymus and are then released into the immune periphery. However, some Tregs populate the thymus and constitute a major subset of yet poorly understood cells. Here we describe a subset of thymus recirculating IL18R+ Tregs with molecular characteristics highly reminiscent of tissue-resident effector Tregs. Moreover, we show that IL18R+ Tregs are endowed with higher capacity to populate the thymus than their IL18R– or IL18R–/– counterparts, highlighting the key role of...
Source: eLife - July 20, 2020 Category: Biomedical Science Tags: Immunology and Inflammation Source Type: research

A single point mutation in the < i > Plasmodium falciparum < /i > FtsH1 metalloprotease confers actinonin resistance
The antibiotic actinonin kills malaria parasites (Plasmodium falciparum) by interfering with apicoplast function. Early evidence suggested that actinonin inhibited prokaryote-like post-translational modification in the apicoplast; mimicking its activity against bacteria. However, Amberg Johnson et al. (2017) identified the metalloproteaseTgFtsH1 as the target of actinonin in the related parasiteToxoplasma gondii and implicatedP. falciparumFtsH1 as a likely target in malaria parasites. The authors were not, however, able to recover actinonin resistant malaria parasites, leaving the specific target of actinonin uncertain. We...
Source: eLife - July 17, 2020 Category: Biomedical Science Tags: Cell Biology Microbiology and Infectious Disease Source Type: research

Meta-Research: Large-scale language analysis of peer review reports
Peer review is often criticized for being flawed, subjective and biased, but research into peer review has been hindered by a lack of access to peer review reports. Here we report the results of a study in which text-analysis software was used to determine the linguistic characteristics of 472,449 peer review reports. A range of characteristics (including analytical tone, authenticity, clout, three measures of sentiment, and morality) were studied as a function of reviewer recommendation, area of research, type of peer review and reviewer gender. We found that reviewer recommendation had the biggest impact on the linguisti...
Source: eLife - July 17, 2020 Category: Biomedical Science Source Type: research

The genetic factors of bilaterian evolution
The Cambrian explosion was a unique animal radiation ~540 million years ago that produced the full range of body plans across bilaterians. The genetic mechanisms underlying these events are unknown, leaving a fundamental question in evolutionary biology unanswered. Using large-scale comparative genomics and advanced orthology evaluation techniques, we identified 157 bilaterian-specific genes. They include the entire Nodal pathway, a key regulator of mesoderm development and left-right axis specification; components for nervous system development, including a suite of G protein-coupled receptors that control physiology and ...
Source: eLife - July 16, 2020 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Trait-associated noncoding variant regions affect < i > TBX3 < /i > regulation and cardiac conduction
Genome-wide association studies have implicated common genomic variants in the gene desert upstream ofTBX3 in cardiac conduction velocity. Whether these noncoding variants affect expression ofTBX3 or neighboring genes and how they affect cardiac conduction is not understood. Here, we use high-throughput STARR-seq to test the entire 1.3 Mb human and mouseTBX3 locus, including two cardiac conduction-associated variant regions, for regulatory function. We identified multiple accessible and functional regulatory DNA elements that harbor variants affecting their activity. Both variant regions drove gene expression in the cardia...
Source: eLife - July 16, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Genetics and Genomics Source Type: research

Drosophila seminal Sex Peptide associates with rival as well as own sperm, providing SP function in polyandrous females
We report that Sex P eptide (SP) that a femaleDrosophila receives from a male can bind sperm that she had stored from a previous male, and rescue the sperm utilization and fertility defects of an SP-deficient first-male. Other seminal proteins received in the first mating 'primed' the sperm (or the female) for this binding. Thus, SP from one male can directly benefit another, making SP a key molecule in inter-ejaculate interaction. (Source: eLife)
Source: eLife - July 16, 2020 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Three-dimensional growth of breast cancer cells potentiates the anti-tumor effects of unacylated ghrelin and AZP-531
We report potent anti-tumor effects of unacylated ghrelin, dependent on cells being cultured in 3D in a biologically-relevant extracellular matrix. The mechanism of unacylated ghrelin-mediated growth inhibition involves activation of G αi and suppression of MAPK signaling. AZP-531 also suppresses the growth of breast cancer cellsin vitro and in xenografts, and may be a novel approach for the safe and effective treatment of breast cancer. (Source: eLife)
Source: eLife - July 15, 2020 Category: Biomedical Science Tags: Cancer Biology Source Type: research

Structures reveal gatekeeping of the mitochondrial Ca < sup > 2+ < /sup > uniporter by MICU1-MICU2
We present a cryo-EM structure of an MCU-EMRE-MICU1-MICU2 holocomplex comprising MCU and EMRE subunits from the beetle Tribolium castaneum in complex with a human MICU1-MICU2 heterodimer at 3.3 Å resolution. With analogy to how neuronal channels are blocked by protein toxins, a uniporter interaction domain on MICU1 binds to a channel receptor site comprising MCU and EMRE subunits to inhibit ion flow under resting Ca2+ conditions. A Ca2+-bound structure of MICU1-MICU2 at 3.1 Å resolution indicates how Ca2+-dependent changes enable dynamic response to cytosolic Ca2+ signals. (Source: eLife)
Source: eLife - July 15, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Structural Biology and Molecular Biophysics Source Type: research

Correction: Genetic dissection of Down syndrome-associated congenital heart defects using a new mouse mapping panel
(Source: eLife)
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Developmental Biology Human Biology and Medicine Source Type: research

Peroxiredoxin promotes longevity and H < sub > 2 < /sub > O < sub > 2 < /sub > -resistance in yeast through redox-modulation of protein kinase A
Peroxiredoxins are H2O2 scavenging enzymes that also carry H2O2 signaling and chaperone functions. In yeast, the major cytosolic peroxiredoxin, Tsa1 is required for both promoting resistance to H2O2 and extending lifespan upon caloric restriction. We show here that Tsa1 effects both these functions not by scavenging H2O2, but by repressing the nutrient signaling Ras-cAMP-PKA pathway at the level of the protein kinase A (PKA) enzyme. Tsa1 stimulates sulfenylation of cysteines in the PKA catalytic subunit by H2O2 and a significant proportion of the catalytic subunits are glutathionylated on two cysteine residues. Redox modif...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

A two-lane mechanism for selective biological ammonium transport
The transport of charged molecules across biological membranes faces the dual problem of accommodating charges in a highly hydrophobic environment while maintaining selective substrate translocation. This has been the subject of a particular controversy for the exchange of ammonium across cellular membranes, an essential process in all domains of life. Ammonium transport is mediated by the ubiquitous Amt/Mep/Rh transporters that includes the human Rhesus factors. Here, using a combination of electrophysiology, yeast functional complementation and extended molecular dynamics simulations, we reveal a unique two-lane pathway ...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Source Type: research

RAB23 coordinates early osteogenesis by repressing FGF10-pERK1/2 and GLI1
Mutations in the gene encodingRas-associated binding protein 23 (RAB23) cause Carpenter Syndrome, which is characterized by multiple developmental abnormalities including polysyndactyly and defects in skull morphogenesis. To understand how RAB23 regulates skull development, we generatedRab23 deficient mice that survive to an age where skeletal development can be studied. Along with polysyndactyly, these mice exhibit premature fusion of multiple sutures resultant from aberrant osteoprogenitor proliferation and elevated osteogenesis in the suture. FGF10 driven FGFR1 signaling is elevated inRab23-/- sutures with a consequent ...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Developmental Biology Human Biology and Medicine Source Type: research

Peroxiredoxin promotes longevity and H2O2-resistance in yeast through redox-modulation of protein kinase A
Peroxiredoxins are H2O2 scavenging enzymes that also carry H2O2 signaling and chaperone functions. In yeast, the major cytosolic peroxiredoxin, Tsa1 is required for both promoting resistance to H2O2 and extending lifespan upon caloric restriction. We show here that Tsa1 effects both these functions not by scavenging H2O2, but by repressing the nutrient signaling Ras-cAMP-PKA pathway at the level of the protein kinase A (PKA) enzyme. Tsa1 stimulates sulfenylation of cysteines in the PKA catalytic subunit by H2O2 and a significant proportion of the catalytic subunits are glutathionylated on two cysteine residues. Redox modif...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

Restricting the sizes of condensates
Computer simulations of model proteins with sticker-and-spacer architectures shed light on the formation of biomolecular condensates in cells. (Source: eLife)
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Physics of Living Systems Structural Biology and Molecular Biophysics Source Type: research

Recurrent circuitry is required to stabilize piriform cortex odor representations across brain states
Pattern completion, or the ability to retrieve stable neural activity patterns from noisy or partial cues, is a fundamental feature of memory. Theoretical studies indicate that recurrently connected auto-associative or discrete attractor networks can perform this process. Although pattern completion and attractor dynamics have been observed in various recurrent neural circuits, the role recurrent circuitry plays in implementing these processes remains unclear. In recordings from head-fixed mice, we found that odor responses in olfactory bulb degrade under ketamine/xylazine anesthesia while responses immediately downstream,...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Proteome-wide analysis of a malaria vaccine study reveals personalized humoral immune profiles in Tanzanian adults
Tanzanian adult male volunteers were immunized by direct venous inoculation with radiation-attenuated, aseptic, purified, cryopreservedPlasmodium falciparum(Pf) sporozoites (PfSPZ Vaccine) and protective efficacy assessed by homologous controlled human malaria infection (CHMI). Serum immunoglobulin G (IgG) responses were analyzed longitudinally using a Pf protein microarray covering 91% of the proteome, providing first insights into naturally acquired and PfSPZ Vaccine-induced whole parasite antibody profiles in malaria pre-exposed Africans. Immunoreactivity was identified against 2,239 functionally diverse Pf proteins, sh...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Epidemiology and Global Health Source Type: research

Does the human placenta express the canonical cell entry mediators for SARS-CoV-2?
We report that co-transcription of ACE2 and TMPRSS2 is negligible in the placenta, thus not a likely path of vertical transmission for SARS-CoV-2. By contrast, receptors for Zika virus and cytomegalovirus, which cause congenital infections, are highly expressed by placental cell types. These data show that the placenta minimally expresses the canonical cell-entry mediators for SARS-CoV-2. (Source: eLife)
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Genetics and Genomics Human Biology and Medicine Source Type: research

Correction: Building customizable auto-luminescent luciferase-based reporters in plants
(Source: eLife)
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Plant Biology Source Type: research

Flotillin-mediated membrane fluidity controls peptidoglycan synthesis and MreB movement
The bacterial plasma membrane is an important cellular compartment. In recent years it has become obvious that protein complexes and lipids are not uniformly distributed within membranes. Current hypotheses suggest that flotillin proteins are required for the formation of complexes of membrane proteins including cell-wall synthetic proteins. We show here that bacterial flotillins are important factors for membrane fluidity homeostasis. Loss of flotillins leads to a decrease in membrane fluidity that in turn leads to alterations in MreB dynamics and, as a consequence, in peptidoglycan synthesis. These alterations are revert...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Cell Biology Microbiology and Infectious Disease Source Type: research

Sleep is bi-directionally modified by amyloid beta oligomers
Disrupted sleep is a major feature of Alzheimer ’s disease (AD), often arising years before symptoms of cognitive decline. Prolonged wakefulness exacerbates the production of amyloid-beta (Aβ) species, a major driver of AD progression, suggesting that sleep loss further accelerates AD through a vicious cycle. However, the mechanisms by which A β affects sleep are unknown. We demonstrate in zebrafish that Aβ acutely and reversibly enhances or suppresses sleep as a function of oligomer length. Genetic disruptions revealed that short Aβ oligomers induce acute wakefulness through Adrenergic receptor b...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Risk of psychiatric disorders among the surviving twins after a co-twin loss
Losing a co-twin by death is a severely stressful event yet with unknown impact on the surviving twin ’s risk of psychiatric disorders. We identified all Swedish-born twins who lost a co-twin by death between 1973 and 2013 (n = 4,528), their 4939 non-twin full siblings, together with 22,640 age- and sex-matched non-bereaved twins. Compared to the non-bereaved twins, exposed twins were at increased risk of receiving a first diagnosis of psychiatric disorders (hazard ratio = 1.65, 95% confidence interval1.48–1.83), particularly during the first month after loss. Similarly, compared to non-twin full siblings, the ...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Epidemiology and Global Health Source Type: research

Stable task information from an unstable neural population
Over days and weeks, neural activity representing an animal's position and movement in sensorimotor cortex has been found to continually reconfigure or 'drift' during repeated trials of learned tasks, with no obvious change in behavior. This challenges classical theories which assume stable engrams underlie stable behavior. However, it is not known whether this drift occurs systematically, allowing downstream circuits to extract consistent information. Analyzing long-term calcium imaging recordings from posterior parietal cortex in mice (Mus musculus), we show that drift is systematically constrained far above chance, faci...
Source: eLife - July 14, 2020 Category: Biomedical Science Tags: Computational and Systems Biology Neuroscience Source Type: research

Cancer systems immunology
Tumor immunology is undergoing a renaissance due to the recent profound clinical successes of tumor immunotherapy. These advances have coincided with an exponential growth in the development of –omics technologies. Armed with these technologies and their associated computational and modeling toolsets, systems biologists have turned their attention to tumor immunology in an effort to understand the precise nature and consequences of interactions between tumors and the immune system. Such interactions are inherently multivariate, spanning multiple time and size scales, cell types, and organ systems, rendering systems b...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Cancer Biology Immunology and Inflammation Source Type: research

Sleep spindles mediate hippocampal-neocortical coupling during long-duration ripples
Sleep is pivotal for memory consolidation. According to two-stage accounts, memory traces are gradually translocated from hippocampus to neocortex during non-rapid-eye-movement (NREM) sleep. Mechanistically, this information transfer is thought to rely on interactions between thalamocortical spindles and hippocampal ripples. To test this hypothesis, we analyzed intracranial and scalp Electroencephalography sleep recordings from pre-surgical epilepsy patients. We first observed a concurrent spindle power increase in hippocampus (HIPP) and neocortex (NC) time-locked to individual hippocampal ripple events. Coherence analysis...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Growth cone-localized microtubule organizing center establishes microtubule orientation in dendrites
A polarized arrangement of neuronal microtubule arrays is the foundation of membrane trafficking and subcellular compartmentalization. Conserved among both invertebrates and vertebrates, axons contain exclusively 'plus-end-out' microtubules while dendrites contain a high percentage of 'minus-end-out' microtubules, the origins of which have been a mystery. Here we show that inCaenorhabditis elegans the dendritic growth cone contains a non-centrosomal microtubule organizing center, which generates minus-end-out microtubules along outgrowing dendrites and plus-end-out microtubules in the growth cone. RAB-11-positive endosomes...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Cell Biology Developmental Biology Source Type: research

Alzheimer's disease risk gene < i > BIN1 < /i > induces Tau-dependent network hyperexcitability
Genome-wide association studies identified theBIN1 locus as a leading modulator of genetic risk in Alzheimer's disease (AD). One limitation in understandingBIN1's contribution to AD is its unknown function in the brain. AD-associatedBIN1 variants are generally noncoding and likely change expression. Here, we determined the effects of increasing expression of the major neuronal isoform of human BIN1 in cultured rat hippocampal neurons. Higher BIN1 induced network hyperexcitability on multielectrode arrays, increased frequency of synaptic transmission, and elevated calcium transients, indicating that increasing BIN1 drives g...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Correction: Optogenetically induced low-frequency correlations impair perception
(Source: eLife)
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Umbilical cord blood-derived ILC1-like cells constitute a novel precursor for mature KIR < sup > + < /sup > NKG2A < sup > - < /sup > NK cells
Despite their identification several years ago, molecular identity and developmental relation between human ILC1 and NK cells, comprising group 1 ILCs, is still elusive. To unravel their connection, thorough transcriptional, epigenetic, and functional characterization was performed from umbilical cord blood (CB). Unexpectedly, ILC1-like cells lacked Tbet expression and failed to produce IFN γ. Moreover, in contrast to previously described ILC1 subsets they could be efficiently differentiated into NK cells. These were characterized by highly diversified KIR repertoires including late stage NKG2A-KIR+ effector cells th...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Immunology and Inflammation Source Type: research

Assigning mitochondrial localization of dual localized proteins using a yeast Bi-Genomic Mitochondrial-Split-GFP
A single nuclear gene can be translated into a dual localized protein that distributes between the cytosol and mitochondria. Accumulating evidences show that mitoproteomes contain lots of these dual localized proteins termed echoforms. Unraveling the existence of mitochondrial echoforms using current GFP (Green Fluorescent Protein) fusion microscopy approaches is extremely difficult because the GFP signal of the cytosolic echoform will almost inevitably mask that of the mitochondrial echoform. We therefore engineered a yeast strain expressing a new type of Split-GFP that we termed Bi-Genomic Mitochondrial-Split-GFP (BiG Mi...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

Ribosome collisions trigger cis-acting feedback inhibition of translation initiation
Translation of aberrant mRNAs can cause ribosomes to stall, leading to collisions with trailing ribosomes. Collided ribosomes are specifically recognized by ZNF598 to initiate protein and mRNA quality control pathways. Here we found using quantitative proteomics of collided ribosomes that EDF1 is a ZNF598-independent sensor of ribosome collisions. EDF1 stabilizes GIGYF2 at collisions to inhibit translation initiationin cis via 4EHP. The GIGYF2 axis acts independently of the ZNF598 axis, but each pathway's output is more pronounced without the other. We propose that the widely conserved and highly abundant EDF1 monitors the...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

Phosphoinositides regulate force-independent interactions between talin, vinculin, and actin
The focal adhesion (FA) proteins talin and vinculin connect integrin to actomyosin networks, acting as the core mechanosensitive FA machinery. Both proteins bind to F-actin and each other, providing a foundation for network formation within FAs. However, the underlying mechanisms regulating their engagement remain unclear. Here, we performedin vitro reconstitution of talin-vinculin-actin assemblies using synthetic membrane systems. Neither talin nor vinculin alone recruit actin filaments to the membrane. In contrast, phosphoinositide-rich membranes recruit and activate talin, and the membrane-bound talin then activates vin...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Cell Biology Structural Biology and Molecular Biophysics Source Type: research

Microtubules originate asymmetrically at the somatic Golgi and are guided via Kinesin2 to maintain polarity in neurons
Neurons contain polarised microtubule arrays essential for neuronal function. How microtubule nucleation and polarity are regulated within neurons remains unclear. We show that γ-tubulin localises asymmetrically to the somatic Golgi withinDrosophila neurons. Microtubules originate from the Golgi with an initial growth preference towards the axon. Their growing plus ends also turn towards and into the axon, adding to the plus-end-out microtubule pool. Any plus ends that reach a dendrite, however, do not readily enter, maintaining minus-end-out polarity. Both turning towards the axon and exclusion from dendrites depend...
Source: eLife - July 13, 2020 Category: Biomedical Science Tags: Cell Biology Neuroscience Source Type: research

Miga-mediated endoplasmic reticulum –mitochondria contact sites regulate neuronal homeostasis
Endoplasmic reticulum (ER) –mitochondria contact sites (ERMCSs) are crucial for multiple cellular processes such as calcium signaling, lipid transport, and mitochondrial dynamics. However, the molecular organization, functions, regulation of ERMCS, and the physiological roles of altered ERMCSs are not fully understood in hi gher eukaryotes. We found that Miga, a mitochondrion located protein, markedly increases ERMCSs and causes severe neurodegeneration upon overexpression in fly eyes. Miga interacts with an ER protein Vap33 through its FFAT-like motif and an amyotrophic lateral sclerosis (ALS) disease related Vap33 ...
Source: eLife - July 10, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

Dissecting cell type-specific metabolism in pancreatic ductal adenocarcinoma
Tumors are composed of many different cell types including cancer cells, fibroblasts, and immune cells. Dissecting functional metabolic differences between cell types within a mixed population can be challenging due to the rapid turnover of metabolites relative to the time needed to isolate cells. To overcome this challenge, we traced isotope-labeled nutrients into macromolecules that turn over more slowly than metabolites. This approach was used to assess differences between cancer cell and fibroblast metabolism in murine pancreatic cancer organoid-fibroblast co-cultures and tumors. Pancreatic cancer cells exhibited incre...
Source: eLife - July 10, 2020 Category: Biomedical Science Tags: Cancer Biology Source Type: research

Miga mediated endoplasmic reticulum-mitochondria contact sites regulate neuronal homeostasis
In this study, we found that Miga, a mitochondrion located protein, markedly increases ERMCSs and causes severe neurodegeneration upon overexpression in fly eyes. Miga interacts with an ER protein Vap33 through its FFAT-like motif and an amyotrophic lateral sclerosis (ALS) disease related Vap33 mutation considerably reduces its interaction with Miga. Multiple serine residues inside and near the Miga FFAT motif were phosphorylated, which is required for its interaction with Vap33 and Miga mediated ERMCS formation. The interac tion between Vap33 and Miga promoted further phosphorylation of upstream serine/threonine clusters,...
Source: eLife - July 10, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

Real-time < i > in vivo < /i > imaging of extracellular ATP in the brain with a hybrid-type fluorescent sensor
Adenosine 5' triphosphate (ATP) is a ubiquitous extracellular signaling messenger. Here, we describe a method forin-vivo imaging of extracellular ATP with high spatiotemporal resolution. We prepared a comprehensive set of cysteine-substitution mutants of ATP-binding protein,Bacillus FoF1-ATP synthase e subunit, labeled with small-molecule fluorophores at the introduced cysteine residue. Screening revealed that the Cy3-labeled glutamine-105 mutant (Q105C-Cy3; designated ATPOS) shows a large fluorescence change in the presence of ATP, with submicromolar affinity, pH-independence, and high selectivity for ATP over ATP metabol...
Source: eLife - July 10, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Neuroscience Source Type: research

Late-life restoration of mitochondrial function reverses cardiac dysfunction in old mice
Diastolic dysfunction is a prominent feature of cardiac aging in both mice and humans. We show here that 8-week treatment of old mice with the mitochondrial targeted peptide SS-31 (elamipretide) can substantially reverse this deficit. SS-31 normalized the increase in proton leak and reduced mitochondrial ROS in cardiomyocytes from old mice, accompanied by reduced protein oxidation and a shift towards a more reduced protein thiol redox state in old hearts. Improved diastolic function was concordant with increased phosphorylation of cMyBP-C Ser282 but was independent of titin isoform shift. Late-life viral expression of mito...
Source: eLife - July 10, 2020 Category: Biomedical Science Tags: Human Biology and Medicine Source Type: research

Evolutionarily distant I domains can functionally replace the essential ligand-binding domain of < i > Plasmodium < /i > TRAP
Inserted (I) domains function as ligand-binding domains in adhesins that support cell adhesion and migration in many eukaryotic phyla. These adhesins include integrin αβ heterodimers in metazoans and single subunit transmembrane proteins in apicomplexans such as TRAP inPlasmodium and MIC2 inToxoplasma. Here we show that the I domain of TRAP is essential for sporozoite gliding motility, mosquito salivary gland invasion and mouse infection. Its replacement with the I domain from Toxoplasma MIC2 fully restores tissue invasion and parasite transmission, while replacement with the aX I domain from human integrins sti...
Source: eLife - July 10, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

A high-throughput small molecule screen identifies farrerol as a potentiator of CRISPR/Cas9-mediated genome editing
Directly modulating the choice between homologous recombination (HR) and non-homologous end joining (NHEJ) - two independent pathways for repairing DNA double-strand breaks (DSBs) - has the potential to improve the efficiency of gene targeting by CRISPR/Cas9. Here, we have developed a rapid and easy-to-score screening approach for identifying small molecules that affect the choice between the two DSB repair pathways. Using this tool, we identified a small molecule, farrerol, that promotes HR but does not affect NHEJ. Further mechanistic studies indicate that farrerol functions through stimulating the recruitment of RAD51 t...
Source: eLife - July 9, 2020 Category: Biomedical Science Tags: Cell Biology Genetics and Genomics Source Type: research

Infant and adult SCA13 mutations differentially affect Purkinje cell excitability, maturation, and viability in vivo
Mutations inKCNC3, which encodes the Kv3.3 K+ channel, cause spinocerebellar ataxia 13 (SCA13). SCA13 exists in distinct forms with onset in infancy or adulthood. Using zebrafish, we tested the hypothesis that infant- and adult-onset mutations differentially affect the excitability and viability of Purkinje cells in vivo during cerebellar development. An infant-onset mutation dramatically and transiently increased Purkinje cell excitability, stunted process extension, impaired dendritic branching and synaptogenesis, and caused rapid cell death during cerebellar development. Reducing excitability increased early Purkinje ce...
Source: eLife - July 9, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Different dendritic domains of the GnRH neuron underlie the pulse and surge modes of GnRH secretion in female mice
The gonadotropin-releasing hormone (GnRH) neurons exhibit pulse and surge modes of activity to control fertility. They also exhibit an unusual bipolar morphology comprised of a classical soma-proximal dendritic zone and an elongated secretory process that can operate as both a dendrite and an axon, termed a ‘dendron’. We show using expansion microscopy that the highest density of synaptic inputs to a GnRH neuron exists at its distal dendron. In vivo, selective chemogenetic inhibition of the GnRH neuron distal dendron abolishes the luteinizing hormone (LH) surge and markedly dampens LH pulses. In co ntrast, inhi...
Source: eLife - July 9, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

An adipokine feedback regulating diurnal food intake rhythms in mice
Endogenous circadian clocks have evolved to anticipate 24-hour rhythms in environmental demands. Recent studies suggest that circadian rhythm disruption is a major risk factor for the development of metabolic disorders in humans. Conversely, alterations in energy state can disrupt circadian rhythms of behavior and physiology, creating a vicious circle of metabolic dysfunction. How peripheral energy state affects diurnal food intake, however, is still poorly understood. We here show that the adipokine adiponectin (ADIPOQ) regulates diurnal feeding rhythms through clocks in energy regulatory centers of the mediobasal hypotha...
Source: eLife - July 9, 2020 Category: Biomedical Science Tags: Genetics and Genomics Neuroscience Source Type: research