Circulating myeloid cells invade the central nervous system to mediate cachexia during pancreatic cancer
Weight loss and anorexia are common symptoms in cancer patients that occur prior to initiation of cancer therapy. Inflammation in the brain is a driver of these symptoms, yet cellular sources of neuroinflammation during malignancy are unknown. In a mouse model of pancreatic ductal adenocarcinoma (PDAC), we observed early and robust myeloid cell infiltration into the brain. Infiltrating immune cells were predominately neutrophils, which accumulated at a unique central nervous system entry portal called the velum interpositum, where they expressed CCR2. Pharmacologic CCR2 blockade and genetic deletion ofCcr2 both resulted in...
Source: eLife - May 11, 2020 Category: Biomedical Science Tags: Immunology and Inflammation Neuroscience Source Type: research

AirID, a novel proximity biotinylation enzyme, for analysis of protein-protein interactions
Proximity biotinylation based onEscherichia coli BirA enzymes like BioID (BirA*) and TurboID is a key technology for identifying proteins interacting with a target protein in a cell or organism. However, there have been some improvements in the enzymes for that purpose. Here, we demonstrate a novel BirA enzyme, AirID (ancestral BirA for proximity-dependent biotin identification), which was designedde novo using an ancestral enzyme reconstruction algorithm and metagenome data. AirID-fusion proteins like AirID-p53 or AirID-I κBα indicated biotinylation of MDM2 or RelA, respectively,in vitro and in cells, respecti...
Source: eLife - May 11, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

Driving polar growth
Profiling the phenotype of 200,000 mutants revealed a new cofactor that may help a group of rod-shaped bacteria elongate and grow. (Source: eLife)
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Temporal integration of auxin information for the regulation of patterning
Positional information is essential for coordinating the development of multicellular organisms. In plants, positional information provided by the hormone auxin regulates rhythmic organ production at the shoot apex, but the spatio-temporal dynamics of auxin gradients is unknown. We used quantitative imaging to demonstrate that auxin carries high-definition graded information not only in space but also in time. We show that, during organogenesis, temporal patterns of auxin arise from rhythmic centrifugal waves of high auxin travelling through the tissue faster than growth. We further demonstrate that temporal integration of...
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Developmental Biology Plant Biology Source Type: research

Spen links RNA-mediated endogenous retrovirus silencing and X chromosome inactivation
The Xist lncRNA mediates X chromosome inactivation (XCI)1,2. Here we show that Spen, an Xist-binding repressor protein essential for XCI3-9, binds to ancient retroviral RNA, performing a surveillance role to recruit chromatin silencing machinery to these parasitic loci. Spen inactivation activates a subset of endogenous retroviral (ERV) elements in mouse embryonic stem cells, with gain of chromatin accessibility, active histone modifications, and ERV RNA transcription. Spen binds directly to ERV RNAs that show structural similarity to the A-repeat of Xist, a region critical for Xist-mediated gene silencing10-11. ERV RNA an...
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Source Type: research

Essential function of the alveolin network in the subpellicular microtubules and conoid assembly in < i > Toxoplasma gondii < /i >
The coccidian subgroup of Apicomplexa possesses an apical complex harboring a conoid, made of unique tubulin polymer fibers. This enigmatic organelle extrudes in extracellular invasive parasites and is associated to the apical polar ring (APR). The APR serves as microtubule-organizing center for the 22 subpellicular microtubules (SPMTs) that are linked to a patchwork of flattened vesicles, via an intricate network composed of alveolins. Here, we capitalize on ultrastructure expansion microscopy (U-ExM) to localize theToxoplasma gondii Apical Cap protein 9 (AC9) and its partner AC10, identified by BioID, to the alveolin net...
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Quantifying antibiotic impact on within-patient dynamics of extended-spectrum beta-lactamase resistance
Antibiotic-induced perturbation of the human gut flora is expected to play an important role in mediating the relationship between antibiotic use and the population prevalence of antibiotic resistance in bacteria, but little is known about how antibiotics affect within-host resistance dynamics. Here we develop a data-driven model of the within-host dynamics of extended-spectrum beta-lactamase (ESBL) producingEnterobacteriaceae. We use blaCTX-M (the most widespread ESBL gene family) and 16S rRNA (a proxy for bacterial load) abundance data from 833 rectal swabs from 133 ESBL-positive patients followed up in a prospective coh...
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Epidemiology and Global Health Microbiology and Infectious Disease Source Type: research

Recurrent circuit dynamics underlie persistent activity in the macaque frontoparietal network
During delayed oculomotor response tasks, neurons in the lateral intraparietal area (LIP) and the frontal eye fields (FEF) exhibit persistent activity that reflects the active maintenance of behaviorally relevant information. Despite many computational models of the mechanisms of persistent activity, there is a lack of circuit-level data from the primate to inform the theories. To fill this gap, we simultaneously recorded ensembles of neurons in both LIP and FEF while macaques performed a memory-guided saccade task. A population encoding model revealed strong and symmetric long-timescale recurrent excitation between LIP an...
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

LKB1 coordinates neurite remodeling to drive synapse layer emergence in the outer retina
Structural changes in pre and postsynaptic neurons that accompany synapse formation often temporally and spatially overlap. Thus, it has been difficult to resolve which processes drive patterned connectivity. To overcome this, we use the laminated outer murine retina. We identify the serine/threonine kinase LKB1 as a key driver of synapse layer emergence. The absence of LKB1 in the retina caused a marked mislocalization and delay in synapse layer formation. In parallel, LKB1 modulated postsynaptic horizontal cell refinement and presynaptic photoreceptor axon growth. Mislocalized horizontal cell processes contacted aberrant...
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Auditory cortical alpha/beta desynchronization prioritizes the representation of memory items during a retention period
To-be-memorized information in working-memory could be protected against distracting influences by processes of functional inhibition or prioritization. Modulations of oscillations in the alpha to beta range in task-relevant sensory regions have been suggested to play an important role for both mechanisms. We adapted a Sternberg task variant to the auditory modality, with a strong or a weak distracting sound presented at a predictable time during the retention period. Using a time-generalized decoding approach relatively decreased strength of memorized information was found prior to strong distractors, paralleled by decrea...
Source: eLife - May 7, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Cryo-EM structures and functional properties of CALHM channels of the human placenta
The transport of substances across the placenta is essential for the development of the fetus. Here, we were interested in the role of channels of the calcium homeostasis modulator (CALHM) family in the human placenta. By transcript analysis, we found the paralogs CALHM2, 4, and 6 to be highly expressed in this organ and upregulated during trophoblast differentiation. Based on electrophysiology, we found that activation of these paralogs differs from the voltage- and calcium-gated channel CALHM1. Cryo-EM structures of CALHM4 display decameric and undecameric assemblies with large cylindrical pore, while in CALHM6 a conform...
Source: eLife - May 6, 2020 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Encouraging cartilage production
A long non-coding RNA calledGRASLND is essential to help stem cells create stable cartilage. (Source: eLife)
Source: eLife - May 6, 2020 Category: Biomedical Science Tags: Stem Cells and Regenerative Medicine Source Type: research

Modelling the climatic suitability of Chagas disease vectors on a global scale
The Triatominae are a vector species forTrypanosoma cruzi, the aetiological agent of the neglected tropical Chagas disease. Their distribution stretches across Latin America, with some species occurring outside of the Americas. In particular, the cosmopolitan vector,Triatoma rubrofasciata, has already been detected in many Asian and African countries. We applied an ensemble forecasting niche modelling approach to project the climatic suitability of 11 triatomine species under current climate conditions on a global scale. Our results revealed potential hotspots of triatomine species diversity in tropical and subtropical reg...
Source: eLife - May 6, 2020 Category: Biomedical Science Tags: Ecology Source Type: research

The histone modification reader ZCWPW1 links histone methylation to PRDM9-induced double strand break repair
The histone modification writer Prdm9 has been shown to deposit H3K4me3 and H3K36me3 at future double-strand break (DSB) sites during the very early stages of meiosis, but the reader of these marks remains unclear. Here, we demonstrate that Zcwpw1 is an H3K4me3 reader that is required for DSB repair and synapsis in mouse testes. We generated H3K4me3 reader-dead Zcwpw1 mutant mice and found that their spermatocytes were arrested at the pachytene-like stage, which phenocopies theZcwpw1 knock –out mice. Based on various ChIP-seq and immunofluorescence analyses using several mutants, we found that Zcwpw1's occupancy on c...
Source: eLife - May 6, 2020 Category: Biomedical Science Tags: Cell Biology Genetics and Genomics Source Type: research

From worms to fish to mice
An multi-species approach can be used to identify small molecules with properties that might prove useful for the treatment of some neuromuscular diseases. (Source: eLife)
Source: eLife - May 6, 2020 Category: Biomedical Science Tags: Human Biology and Medicine Source Type: research

Protein phosphatase 1 activity controls a balance between collective and single cell modes of migration
We present evidence that Pp1 promotes proper levels of cadherin-catenin complex proteins at cell-cell junctions within the cluster to keep border cells together. Pp1 further restricts actomyosin contractility to the cluster periphery rather than at individual internal border cell contacts. We show that the myosin phosphatase Pp1 complex, which inhibits non-muscle myosin-II (Myo-II) activity, coordinates border cell shape and cluster cohesion. Given the high conservation of Pp1 complexes, this study identifies Pp1 as a major regulator of collective versus single cell migration. (Source: eLife)
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Cell Biology Developmental Biology Source Type: research

Keratin 14-dependent disulfides regulate epidermal homeostasis and barrier function via 14-3-3 σ and YAP1
The intermediate filament protein keratin 14 (K14) provides vital structural support in basal keratinocytes of epidermis. Recent studies evidenced a role for K14-dependent disulfide bonding in the organization and dynamics of keratin IFs in skin keratinocytes. Here we report that knock-in mice harboring a cysteine-to-alanine substitution atKrt14's codon 373 (C373A) exhibit alterations in disulfide-bonded K14 species and a barrier defect secondary to enhanced proliferation, faster transit time and altered differentiation in epidermis. A proteomics screen identified 14-3-3 as K14 interacting proteins. Follow-up studies showe...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Cell Biology Source Type: research

Role of IL-4 in bone marrow driven dysregulated angiogenesis and age-related macular degeneration
Age-associated sterile inflammation can cause dysregulated choroidal neovascularization (CNV) as age-related macular degeneration (AMD). Intraocular fluid screening of 234 AMD patients identified high levels of IL-4. The purpose of this study was to determine the functional role of IL-4 in CNV formation using murine CNV model. Our results indicate that the IL-4/IL-4 receptors (IL4Rs) controlled tube formation and global proangiogenic responses of bone marrow cells. CCR2+ bone marrow cells were recruited to form very early CNV lesions. IL-4 rapidly induces CCL2, which enhances recruitment of CCR2+ bone marrow cells. This in...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Human Biology and Medicine Source Type: research

Cortical excitability controls the strength of mental imagery
Mental imagery provides an essential simulation tool for remembering the past and planning the future, with its strength affecting both cognition and mental health. Research suggests that neural activity spanning prefrontal, parietal, temporal, and visual areas supports the generation of mental images. Exactly how this network controls the strength of visual imagery remains unknown. Here, brain imaging and transcranial magnetic phosphene data show that lower resting activity and excitability levels in early visual cortex (V1-V3) predict stronger sensory imagery. Further, electrically decreasing visual cortex excitability u...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Controlling gene activation by enhancers through a drug-inducible topological insulator
While regulation of gene-enhancer interaction is intensively studied, its application remains limited. Here, we reconstituted arrays of CTCF-binding sites and devised asynthetictopologicalinsulator withtetO forchromatin-engineering (STITCH). By coupling STITCH with tetR linked to the KRAB domain to induce heterochromatin and disable the insulation, we developed a drug-inducible system to control gene activation by enhancers. In human induced pluripotent stem cells, STITCH inserted betweenMYC and the enhancer down-regulatedMYC. Progressive mutagenesis of STITCH led to a preferential escalation of the gene-enhancer interacti...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Chromosomes and Gene Expression Genetics and Genomics Source Type: research

The tumor microenvironment as a metabolic barrier to effector T cells and immunotherapy
Breakthroughs in anti-tumor immunity have led to unprecedented advances in immunotherapy, yet it is now clear that the tumor microenvironment (TME) restrains immunity. T cells must substantially increase nutrient uptake to mount a proper immune response and failure to obtain sufficient nutrients or engage the appropriate metabolic pathways can alter or prevent effector T cell differentiation and function. The TME, however, can be metabolically hostile due to insufficient vascular exchange and cancer cell metabolism that leads to hypoxia, depletion of nutrients, and accumulation of waste products. Further, inhibitory recept...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Cancer Biology Immunology and Inflammation Source Type: research

< i > Caenorhabditis elegans < /i > processes sensory information to choose between freeloading and self-defense strategies
Hydrogen peroxide is the preeminent chemical weapon that organisms use for combat. Individual cells rely on conserved defenses to prevent and repair peroxide-induced damage, but whether similar defenses might be coordinated across cells in animals remains poorly understood. Here, we identify a neuronal circuit in the nematodeCaenorhabditis elegans that processes information perceived by two sensory neurons to control the induction of hydrogen peroxide defenses in the organism. We found that catalases produced byEscherichia coli, the nematode's food source, can deplete hydrogen peroxide from the local environment and thereb...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Developmental Biology Neuroscience Source Type: research

Zebrafish macrophage developmental arrest underlies depletion of microglia and reveals Csf1r-independent metaphocytes
Macrophages derive from multiple sources of hematopoietic progenitors. Most macrophages require colony-stimulating factor 1 receptor (CSF1R), but some macrophages persist in the absence of CSF1R. Here, we analyzedmpeg1:GFP –expressing macrophages incsf1r-deficient zebrafish and report that embryonic macrophages emerge followed by their developmental arrest. In larvae,mpeg1+ cell numbers then increased showing two distinct types in the skin: branched, putative Langerhans cells, and amoeboid cells. In contrast, although numbers also increased incsf1r-mutants, exclusively amoeboidmpeg1+cells were present, which we showe...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

A role for CIM6P/IGF2 receptor in memory consolidation and enhancement
Cation-independent mannose-6-phosphate receptor, also called insulin-like growth factor two receptor (CIM6P/IGF2R), plays important roles in growth and development, but is also extensively expressed in the mature nervous system, particularly in the hippocampus, where its functions are largely unknown. One of its major ligands, IGF2, is critical for long-term memory formation and strengthening. Using CIM6P/IGF2R inhibition in rats and neuron-specific knockdown in mice, here we show that hippocampal CIM6P/IGF2R is necessary for hippocampus-dependent memory consolidation, but dispensable for learning, memory retrieval, and re...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Control of brown adipose tissue adaptation to nutrient stress by the activin receptor ALK7
Adaptation to nutrient availability is crucial for survival. Upon nutritional stress, such as during prolonged fasting or cold exposure, organisms need to balance the feeding of tissues and the maintenance of body temperature. The mechanisms that regulate the adaptation of brown adipose tissue (BAT), a key organ for non-shivering thermogenesis, to variations in nutritional state are not known. Here we report that specific deletion of the activin receptor ALK7 in BAT resulted in fasting-induced hypothermia due to exaggerated catabolic activity in brown adipocytes. After overnight fasting, BAT lacking ALK7 showed increased e...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Cell Biology Human Biology and Medicine Source Type: research

A compositional neural code in high-level visual cortex can explain jumbled word reading
We read jubmled wrods effortlessly, but the neural correlates of this remarkable ability remain poorly understood. We hypothesized that viewing a jumbled word activates a visual representation that is compared to known words. To test this hypothesis, we devised a purely visual model in which neurons tuned to letter shape respond to longer strings in a compositional manner by linearly summing letter responses. We found that dissimilarities between letter strings in this model can explain human performance on visual search, and responses to jumbled words in word reading tasks. Brain imaging revealed that viewing a string act...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Synergistic and antagonistic drug interactions in the treatment of systemic fungal infections
Invasive fungal infections cause 1.6 million deaths annually, primarily in immunocompromised individuals. Mortality rates are as high as 90% due to limited treatments. The azole class antifungal, fluconazole, is widely available and has multi-species activity but only inhibits growth instead of killing fungal cells, necessitating long treatments. To improve treatment, we used our novel high-throughput method, the overlap2 method (O2M) to identify drugs that interact with fluconazole, either increasing or decreasing efficacy. We identified 40 molecules that act synergistically (amplify activity) and 19 molecules that act an...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Genetics and Genomics Microbiology and Infectious Disease Source Type: research

mRNA decapping is an evolutionarily conserved modulator of neuroendocrine signaling that controls development and ageing
Eukaryotic 5 ’−3’ mRNA decay plays important roles during development and in response to stress, regulating gene expression post-transcriptionally. InCaenorhabditis elegans, deficiency of DCAP-1/DCP1, the essential co-factor of the major cytoplasmic mRNA decapping enzyme, impacts normal development, stress survival and ageing. Here, we show that overexpression ofdcap-1 in neurons of worms is sufficient to increase lifespan through the function of the insulin/IGF-like signaling and its effector DAF-16/FOXO transcription factor. Neuronal DCAP-1 affects basal levels of INS-7, an ageing-related insulin-like p...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Genetics and Genomics Source Type: research

Whole-brain mapping of socially isolated zebrafish reveals that lonely fish are not loners
The zebrafish was used to assess the impact of social isolation on behaviour and brain function. As in humans and other social species, early social deprivation reduced social preference in juvenile zebrafish. Whole-brain functional maps of anti-social isolated (lonely) fish were distinct from anti-social (loner) fish found in the normal population. These isolation-induced activity changes revealed profound disruption of neural activity in brain areas linked to social behaviour, social cue processing, and anxiety/stress. Several of the affected regions are modulated by serotonin, and we found that social preference in isol...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Quantification of the pace of biological aging in humans through a blood test, The DunedinPoAm DNA methylation algorithm
We report a blood-DNA-methylation measure that is sensitive to variation in pace of biological aging among individuals born the same year. We first modeled change-over-time in 18 biomarkers tracking organ-system integrity across 12 years of follow-up in n=954 members of the Dunedin Study born in 1972-1973. Rates of change in each biomarker over ages 26-38 years were composited to form a measure of aging-related decline, termed Pace-of-Aging. Elastic-net regression was used to develop a DNA-methylation predictor of Pace-of-Aging, called DunedinPoAm for Dunedin(P)ace(o)f(A)ging(m)ethylation. Validation analysis in cohort stu...
Source: eLife - May 5, 2020 Category: Biomedical Science Tags: Epidemiology and Global Health Source Type: research

The antibiotic bedaquiline activates host macrophage innate immune resistance to bacterial infection
Antibiotics are widely used in the treatment of bacterial infections. Although known for their microbicidal activity, antibiotics may also interfere with the host ’s immune system. Here, we analyzed the effects of bedaquiline (BDQ), an inhibitor of the mycobacterial ATP synthase, on human macrophages. Genome-wide gene expression analysis revealed that BDQ reprogramed cells into potent bactericidal phagocytes. We found that 579 and 1,495 genes were respectiv ely differentially expressed in naive- andM. tuberculosis-infected macrophages incubated with the drug, with an over-representation of lysosome-associated genes. ...
Source: eLife - May 4, 2020 Category: Biomedical Science Tags: Immunology and Inflammation Microbiology and Infectious Disease Source Type: research

Intracellular calcium leak lowers glucose storage in human muscle, promoting hyperglycemia and diabetes
Most glucose is processed in muscle, for energy or glycogen stores. Malignant Hyperthermia Susceptibility (MHS) exemplifies muscle conditions that increase [Ca2+]cytosol. 42% of MHS patients have hyperglycemia. We show that phosphorylated glycogen phosphorylase (GPa), glycogen synthase (GSa) – respectively activated and inactivated by phosphorylation – and their Ca2+-dependent kinase (PhK), are elevated in microsomal extracts from MHS patients' muscle. Glycogen and glucose transporter GLUT4 are decreased. [Ca2+]cytosol, increased to MHS levels, promoted GP phosphorylation. Imaging at ~100 nm resolution located ...
Source: eLife - May 4, 2020 Category: Biomedical Science Tags: Human Biology and Medicine Structural Biology and Molecular Biophysics Source Type: research

Parkin contributes to synaptic vesicle autophagy in Bassoon-deficient mice
Mechanisms regulating the turnover of synaptic vesicle (SV) proteins are not well understood. They are thought to require poly-ubiquitination and degradation through proteasome, endo-lysosomal or autophagy-related pathways. Bassoon was shown to negatively regulate presynaptic autophagy in part by scaffolding Atg5. Here, we show that increased autophagy inBassoon knockout neurons depends on poly-ubiquitination and that the loss of Bassoon leads to elevated levels of ubiquitinated synaptic proteins per se. Our data show thatBassoon knockout neurons have a smaller SV pool size and a higher turnover rate as indicated by a youn...
Source: eLife - May 4, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Wireless recording from unrestrained monkeys reveals motor goal encoding beyond immediate reach in frontoparietal cortex
We present an experimental environment (Reach Cage) and a versatile visuo-haptic interaction system (MaCaQuE) for investigating goal-directed whole-body movements of unrestrained monkeys. Two rhesus monkeys conducted instructed walk-and-reach movements towards targets flexibly positioned in the cage. We tracked 3D multi-joint arm and head movements using markerless motion capture. Movements show small trial-to-trial variability despite being unrestrained. We wirelessly recorded 192 broad-band neural signals from three cortical sensorimotor areas simultaneously. Single unit activity is selective for different reach and walk...
Source: eLife - May 4, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Efficient recognition of facial expressions does not require motor simulation
What mechanisms underlie facial expression recognition? A popular hypothesis holds that efficient facial expression recognition cannot be achieved by visual analysis alone but additionally requires a mechanism of motor simulation — an unconscious, covert imitation of the observed facial postures and movements. Here, we first discuss why this hypothesis does not necessarily follow from extant empirical evidence. Next, we report experimental evidence against the central premise of this view: we demonstrate that individuals c an achieve normotypical efficient facial expression recognition despite a congenital absence of...
Source: eLife - May 4, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

Lipid accumulation controls the balance between surface connection and scission of caveolae
Caveolae are bulb-shaped invaginations of the plasma membrane (PM) that undergo scission and fusion at the cell surface and are enriched in specific lipids. However, the influence of lipid composition on caveolae surface stability is not well described or understood. Accordingly, we inserted specific lipids into the cell PM via membrane fusion and studied their acute effects on caveolae dynamics. We demonstrate that sphingomyelin stabilizes caveolae to the cell surface, while cholesterol and glycosphingolipids drive caveolae scission from the PM. Whilst all three lipids accumulated specifically in caveolae, cholesterol and...
Source: eLife - May 4, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Cell Biology Source Type: research

Intravascular flow stimulates PKD2 (polycystin-2) channels in endothelial cells to reduce blood pressure
PKD2 (polycystin-2, TRPP1), a TRP polycystin channel, is expressed in endothelial cells (ECs), but its physiological functions in this cell type are unclear. Here, we generated inducible, EC-specificPkd2 knockout mice to examine vascular functions of PKD2. Data show that a broad range of intravascular flow rates stimulate EC PKD2 channels, producing vasodilation. Flow-mediated PKD2 channel activation leads to calcium influx that activates SK/IK channels and eNOS serine 1176 phosphorylation in ECs. These signaling mechanisms produce arterial hyperpolarization and vasodilation. In contrast, EC PKD2 channels do not contribute...
Source: eLife - May 4, 2020 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Hfq CLASH uncovers sRNA-target interaction networks linked to nutrient availability adaptation
By shaping gene expression profiles, small RNAs (sRNAs) enable bacteria to efficiently adapt to changes in their environment. To better understand howEscherichia coli acclimatizes to nutrient availability, we performed UV cross-linking, ligation and sequencing of hybrids (CLASH) to uncover Hfq-associated RNA-RNA interactions at specific growth stages. We demonstrate that Hfq CLASH robustly capturesbona fide RNA-RNA interactions identified hundreds of novel sRNA base-pairing interactions, including many sRNA-sRNA interactions and involving 3'UTR-derived sRNAs. We rediscovered known and identified novel sRNA seed sequences. ...
Source: eLife - May 1, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Chromosomes and Gene Expression Source Type: research

A big-data approach to understanding metabolic rate and response to obesity in laboratory mice
Maintaining a healthy body weight requires an exquisite balance between energy intake and energy expenditure. To understand the genetic and environmental factors that contribute to the regulation of body weight, an important first step is to establish the normal range of metabolic values and primary sources contributing to variability. Energy metabolism is measured by powerful and sensitive indirect calorimetry devices. Analysis of nearly 10,000 wild-type mice from two large-scale experiments revealed that the largest variation in energy expenditure is due to body composition, ambient temperature, and institutional site of...
Source: eLife - May 1, 2020 Category: Biomedical Science Tags: Human Biology and Medicine Neuroscience Source Type: research

Expansion microscopy of < i > C. elegans < /i >
We recently developed expansion microscopy (ExM), which achieves nanoscale-precise imaging of specimens at ~70 nm resolution (with ~4.5x linear expansion) by isotropic swelling of chemically processed, hydrogel-embedded tissue. ExM ofC. elegans is challenged by its cuticle, which is stiff and impermeable to antibodies. Here we present a strategy, expansion ofC. elegans (ExCel), to expand fixed, intactC. elegans. ExCel enables simultaneous readout of fluorescent proteins, RNA, DNA location, and anatomical structures at resolutions of ~65 –75 nm (3.3–3.8x linear expansion). We also developed epitope-preserving Ex...
Source: eLife - May 1, 2020 Category: Biomedical Science Tags: Developmental Biology Neuroscience Source Type: research

Principles of operation of a cerebellar learning circuit
We provide behavioral evidence using monkey smooth pursuit eye movements for four principles of cerebellar learning. Using a circuit-level model of the cerebellum, we link behavioral data to learning's neural implementation. The four principles are: (1) early, fast, acquisition driven by climbing fiber inputs to the cerebellar cortex, with poor retention; (2) learned responses of Purkinje cells guide transfer of learning from the cerebellar cortex to the deep cerebellar nucleus, with excellent retention; (3) functionally different neural signals are subject to learning in the cerebellar cortex versus the deep cerebellar nu...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

SKAP2 is required for defense against < i > K. pneumoniae < /i > infection and neutrophil respiratory burst
In conclusion, SKAP2-dependent signaling in neutrophils is essential forK. pneumoniae-activated ROS production and for promoting bacterial clearance during infection. (Source: eLife)
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Immunology and Inflammation Microbiology and Infectious Disease Source Type: research

Effects of fluorescent glutamate indicators on neurotransmitter diffusion and uptake
Genetically encoded fluorescent glutamate indicators (iGluSnFRs) enable neurotransmitter release and diffusion to be visualized in intact tissue. Synaptic iGluSnFR signal time courses vary widely depending on experimental conditions, often lasting 10-100 times longer than the extracellular lifetime of synaptically released glutamate estimated with uptake measurements. iGluSnFR signals typically also decay much more slowly than the unbinding kinetics of the indicator. To resolve these discrepancies, here we have modeled synaptic glutamate diffusion, uptake and iGluSnFR activation to identify factors influencing iGluSnFR sig...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research

DASC, a sensitive classifier for measuring discrete early stages in clathrin-mediated endocytosis
Clathrin-mediated endocytosis (CME) in mammalian cells is driven by resilient machinery that includes>70 endocytic accessory proteins (EAP). Accordingly, perturbation of individual EAPs often results in minor effects on biochemical measurements of CME, thus providing inconclusive/misleading information regarding EAP function. Live-cell imaging can detect earlier roles of EAPs preceding cargo internalization; however, this approach has been limited because unambiguously distinguishing abortive coats (ACs) frombona fide clathrin-coated pits (CCPs) is required but unaccomplished. Here, we develop a thermodynamics-inspired ...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Cell Biology Computational and Systems Biology Source Type: research

Dual histone methyl reader ZCWPW1 facilitates repair of meiotic double strand breaks in male mice
Meiotic crossovers result from homology-directed repair of DNA double-strand breaks (DSBs). Unlike yeast and plants, where DSBs are generated near gene promoters, in many vertebrates DSBs are enriched at hotspots determined by the DNA binding activity of the rapidly evolving zinc finger array of PRDM9 (PR domain zinc finger protein 9). PRDM9 subsequently catalyzes tri-methylation of lysine 4 and lysine 36 of Histone H3 in nearby nucleosomes. Here, we identify the dual histone methylation reader ZCWPW1, which is tightly co-expressed during spermatogenesis withPrdm9, as an essential meiotic recombination factor required for ...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Developmental Biology Genetics and Genomics Source Type: research

An advanced cell cycle tag toolbox reveals principles underlying temporal control of structure-selective nucleases
Cell cycle tags allow to restrict target protein expression to specific cell cycle phases. Here, we present an advanced toolbox of cell cycle tag constructs in budding yeast with defined and compatible peak expression that allow comparison of protein functionality at different cell cycle phases. We apply this technology to the question of how and when Mus81-Mms4 and Yen1 nucleases act on DNA replication or recombination structures. Restriction of Mus81-Mms4 to M phase but not S phase allows awildtyperesponse to various forms of replication perturbation and DNA damage in S phase, suggesting it acts as a post-replicative res...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Chromosomes and Gene Expression Source Type: research

Yap-lin28a axis targets let7-Wnt pathway to restore progenitors for initiating regeneration
The sox2 expressing (sox2+) progenitors in adult mammalian inner ear lose the capacity to regenerate while progenitors in the zebrafish lateral line are able to proliferate and regenerate damaged HCs throughout lifetime. To mimic the HC damage in mammals we have established a zebrafish severe injury model to eliminate both progenitors and HCs. Theatoh1a expressing (atoh1a+) HC precursors were the main population that survived post severe injury, and gained sox2 expression to initiate progenitor regeneration. In response to severe injury, yap was activated to upregulatelin28a transcription. Severe-injury-induced progenitor ...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Polar pattern formation induced by contact following locomotion in a multicellular system
Biophysical mechanisms underlying collective cell migration of eukaryotic cells have been studied extensively in recent years. One mechanism that induces cells to correlate their motions is contact inhibition of locomotion, by which cells migrating away from the contact site. Here, we report that tail-following behavior at the contact site, termed contact following locomotion (CFL), can induce a non-trivial collective behavior in migrating cells. We show the emergence of a traveling band showing polar order in a mutantDictyostelium cell that lacks chemotactic activity. We find that CFL is the cell –cell interaction u...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Physics of Living Systems Source Type: research

Collective forces of tumor spheroids in three-dimensional biopolymer networks
We describe a method for quantifying the contractile forces that tumor spheroids collectively exert on highly nonlinear three-dimensional collagen networks. While three-dimensional traction force microscopy for single cells in a nonlinear matrix is computationally complex due to the variable cell shape, here we exploit the spherical symmetry of tumor spheroids to derive a scale-invariant relationship between spheroid contractility and the surrounding matrix deformations. This relationship allows us to directly translate the magnitude of matrix deformations to the total contractility of arbitrarily sized spheroids. We show ...
Source: eLife - April 30, 2020 Category: Biomedical Science Tags: Cancer Biology Physics of Living Systems Source Type: research

Probabilistic, spinally-gated control of bladder pressure and autonomous micturition by Barrington's nucleus CRH neurons
Micturition requires precise control of bladder and urethral sphincter via parasympathetic, sympathetic and somatic motoneurons. This involves a spino-bulbospinal control circuit incorporating Barrington's nucleus in the pons (Barr). Ponto-spinal glutamatergic neurons that express corticotrophin-releasing hormone (CRH) form one of the largest Barr cell populations. BarrCRH neurons can generate bladder contractions, but it is unknown whether they act as a simple switch or provide a high-fidelity pre-parasympathetic motor drive and whether their activation can actually trigger voids. Combined opto- and chemo-genetic manipula...
Source: eLife - April 29, 2020 Category: Biomedical Science Tags: Neuroscience Source Type: research