ABSTRACT
Serotonin influences many aspects of animal behavior. But how serotonin acts on its diverse receptors across the brain to modulate global activity and behavior is unknown. Here, we examine how serotonin release in C. elegans alters brain-wide activity to induce foraging behaviors, like slow locomotion and increased feeding. Comprehensive genetic analyses identify three core serotonin receptors (MOD-1, SER-4, and LGC-50) that induce slow locomotion upon serotonin release and others (SER-1, SER-5, and SER-7) that interact with them to modulate this behavior. SER-4 induces behavioral responses to sudden increases in serotonin release, whereas MOD-1 induces responses to persistent release. Whole-brain imaging reveals widespread serotonin-associated brain dynamics, spanning many behavioral networks. We map all sites of serotonin receptor expression in the connectome, which, together with synaptic connectivity, helps predict which neurons show serotonin-associated activity. These results reveal how serotonin acts at defined sites across a connectome to modulate brain-wide activity and behavior.
Subject(s)
Caenorhabditis elegans Proteins , Caenorhabditis elegans , Animals , Caenorhabditis elegans/metabolism , Serotonin/metabolism , Caenorhabditis elegans Proteins/metabolism , Receptors, Serotonin/genetics , Receptors, Serotonin/metabolism , Behavior, Animal/physiology , Brain/metabolismABSTRACT
Proper preimplantation development is essential to assemble a blastocyst capable of implantation. Live imaging has uncovered major events driving early development in mouse embryos; yet, studies in humans have been limited by restrictions on genetic manipulation and lack of imaging approaches. We have overcome this barrier by combining fluorescent dyes with live imaging to reveal the dynamics of chromosome segregation, compaction, polarization, blastocyst formation, and hatching in the human embryo. We also show that blastocyst expansion mechanically constrains trophectoderm cells, causing nuclear budding and DNA shedding into the cytoplasm. Furthermore, cells with lower perinuclear keratin levels are more prone to undergo DNA loss. Moreover, applying trophectoderm biopsy, a mechanical procedure performed clinically for genetic testing, increases DNA shedding. Thus, our work reveals distinct processes underlying human development compared with mouse and suggests that aneuploidies in human embryos may not only originate from chromosome segregation errors during mitosis but also from nuclear DNA shedding.
Subject(s)
Preimplantation Diagnosis , Pregnancy , Female , Humans , Animals , Mice , Preimplantation Diagnosis/methods , Blastocyst , Embryo Implantation , Genetic Testing/methods , Aneuploidy , Biopsy/methodsABSTRACT
Changes in an animal's behavior and internal state are accompanied by widespread changes in activity across its brain. However, how neurons across the brain encode behavior and how this is impacted by state is poorly understood. We recorded brain-wide activity and the diverse motor programs of freely moving C. elegans and built probabilistic models that explain how each neuron encodes quantitative behavioral features. By determining the identities of the recorded neurons, we created an atlas of how the defined neuron classes in the C. elegans connectome encode behavior. Many neuron classes have conjunctive representations of multiple behaviors. Moreover, although many neurons encode current motor actions, others integrate recent actions. Changes in behavioral state are accompanied by widespread changes in how neurons encode behavior, and we identify these flexible nodes in the connectome. Our results provide a global map of how the cell types across an animal's brain encode its behavior.
Subject(s)
Caenorhabditis elegans , Connectome , Animals , Brain/cytology , Brain/metabolism , Models, Statistical , Neurons/metabolismABSTRACT
We assembled a semi-automated reconstruction of L2/3 mouse primary visual cortex from â¼250 × 140 × 90 µm3 of electron microscopic images, including pyramidal and non-pyramidal neurons, astrocytes, microglia, oligodendrocytes and precursors, pericytes, vasculature, nuclei, mitochondria, and synapses. Visual responses of a subset of pyramidal cells are included. The data are publicly available, along with tools for programmatic and three-dimensional interactive access. Brief vignettes illustrate the breadth of potential applications relating structure to function in cortical circuits and neuronal cell biology. Mitochondria and synapse organization are characterized as a function of path length from the soma. Pyramidal connectivity motif frequencies are predicted accurately using a configuration model of random graphs. Pyramidal cells receiving more connections from nearby cells exhibit stronger and more reliable visual responses. Sample code shows data access and analysis.
Subject(s)
Neocortex , Animals , Mice , Microscopy, Electron , Neocortex/physiology , Organelles , Pyramidal Cells/physiology , Synapses/physiologyABSTRACT
Neutron stars and stellar-mass black holes are the remnants of massive star explosions1. Most massive stars reside in close binary systems2, and the interplay between the companion star and the newly formed compact object has been theoretically explored3, but signatures for binarity or evidence for the formation of a compact object during a supernova explosion are still lacking. Here we report a stripped-envelope supernova, SN 2022jli, which shows 12.4-day periodic undulations during the declining light curve. Narrow Hα emission is detected in late-time spectra with concordant periodic velocity shifts, probably arising from hydrogen gas stripped from a companion and accreted onto the compact remnant. A new Fermi-LAT γ-ray source is temporally and positionally consistent with SN 2022jli. The observed properties of SN 2022jli, including periodic undulations in the optical light curve, coherent Hα emission shifting and evidence for association with a γ-ray source, point to the explosion of a massive star in a binary system leaving behind a bound compact remnant. Mass accretion from the companion star onto the compact object powers the light curve of the supernova and generates the γ-ray emission.
ABSTRACT
Recent genomic analyses of pathologically defined tumor types identify "within-a-tissue" disease subtypes. However, the extent to which genomic signatures are shared across tissues is still unclear. We performed an integrative analysis using five genome-wide platforms and one proteomic platform on 3,527 specimens from 12 cancer types, revealing a unified classification into 11 major subtypes. Five subtypes were nearly identical to their tissue-of-origin counterparts, but several distinct cancer types were found to converge into common subtypes. Lung squamous, head and neck, and a subset of bladder cancers coalesced into one subtype typified by TP53 alterations, TP63 amplifications, and high expression of immune and proliferation pathway genes. Of note, bladder cancers split into three pan-cancer subtypes. The multiplatform classification, while correlated with tissue-of-origin, provides independent information for predicting clinical outcomes. All data sets are available for data-mining from a unified resource to support further biological discoveries and insights into novel therapeutic strategies.
Subject(s)
Neoplasms/classification , Neoplasms/genetics , Cluster Analysis , Humans , Neoplasms/pathology , TranscriptomeABSTRACT
Many animals use Earth's magnetic field (also known as the geomagnetic field) for navigation1. The favoured mechanism for magnetosensitivity involves a blue-light-activated electron-transfer reaction between flavin adenine dinucleotide (FAD) and a chain of tryptophan residues within the photoreceptor protein CRYPTOCHROME (CRY). The spin-state of the resultant radical pair, and therefore the concentration of CRY in its active state, is influenced by the geomagnetic field2. However, the canonical CRY-centric radical-pair mechanism does not explain many physiological and behavioural observations2-8. Here, using electrophysiology and behavioural analyses, we assay magnetic-field responses at the single-neuron and organismal levels. We show that the 52 C-terminal amino acid residues of Drosophila melanogaster CRY, lacking the canonical FAD-binding domain and tryptophan chain, are sufficient to facilitate magnetoreception. We also show that increasing intracellular FAD potentiates both blue-light-induced and magnetic-field-dependent effects on the activity mediated by the C terminus. High levels of FAD alone are sufficient to cause blue-light neuronal sensitivity and, notably, the potentiation of this response in the co-presence of a magnetic field. These results reveal the essential components of a primary magnetoreceptor in flies, providing strong evidence that non-canonical (that is, non-CRY-dependent) radical pairs can elicit magnetic-field responses in cells.
Subject(s)
Cryptochromes , Drosophila melanogaster , Magnetic Fields , Animals , Cryptochromes/chemistry , Cryptochromes/metabolism , Drosophila melanogaster/chemistry , Drosophila melanogaster/cytology , Drosophila melanogaster/metabolism , Drosophila melanogaster/physiology , Flavin-Adenine Dinucleotide/metabolism , Tryptophan/metabolism , Electrophysiology , Behavior, Animal , Single-Cell Analysis , Neurons/cytology , Neurons/metabolismABSTRACT
In the absence of antiretroviral therapy (ART), a subset of individuals, termed HIV controllers, have levels of plasma viremia that are orders of magnitude lower than non-controllers (NC) who are at higher risk for HIV disease progression. In addition to having fewer infected cells resulting in fewer cells with HIV RNA, it is possible that lower levels of plasma viremia in controllers are due to a lower fraction of the infected cells having HIV-1 unspliced RNA (HIV usRNA) compared with NC. To directly test this possibility, we used sensitive and quantitative single-cell sequencing methods to compare the fraction of infected cells that contain one or more copies of HIV usRNA in peripheral blood mononuclear cells (PBMC) obtained from controllers and NC. The fraction of infected cells containing HIV usRNA did not differ between the two groups. Rather, the levels of viremia were strongly associated with the total number of infected cells that had HIV usRNA, as reported by others, with controllers having 34-fold fewer infected cells per million PBMC. These results reveal that viremic control is not associated with a lower fraction of proviruses expressing HIV usRNA, unlike what is reported for elite controllers, but is only related to having fewer infected cells overall, maybe reflecting greater immune clearance of infected cells. Our findings show that proviral silencing is not a key mechanism for viremic control and will help to refine strategies toward achieving HIV remission without ART.
Subject(s)
HIV Infections , HIV-1 , Leukocytes, Mononuclear , RNA, Viral , Viremia , Humans , HIV-1/genetics , HIV-1/physiology , HIV Infections/virology , HIV Infections/drug therapy , RNA, Viral/genetics , Viremia/virology , Leukocytes, Mononuclear/virology , Male , Viral Load , Female , Adult , Middle AgedABSTRACT
The latent reservoir for HIV-1 in resting memory CD4+ T cells is the major barrier to curing HIV-1 infection. Studies of HIV-1 latency have focused on regulation of viral gene expression in cells in which latent infection is established. However, it remains unclear how infection initially becomes latent. Here we described a unique set of properties of CD4+ T cells undergoing effector-to-memory transition including temporary upregulation of CCR5 expression and rapid downregulation of cellular gene transcription. These cells allowed completion of steps in the HIV-1 life cycle through integration but suppressed HIV-1 gene transcription, thus allowing the establishment of latency. CD4+ T cells in this stage were substantially more permissive for HIV-1 latent infection than other CD4+ T cells. Establishment of latent HIV-1 infection in CD4+ T could be inhibited by viral-specific CD8+ T cells, a result with implications for elimination of latent HIV-1 infection by T cell-based vaccines.
Subject(s)
CD4-Positive T-Lymphocytes/immunology , Cellular Reprogramming/immunology , HIV-1/immunology , Immunologic Memory/immunology , Transcription, Genetic , CD4-Positive T-Lymphocytes/metabolism , CD4-Positive T-Lymphocytes/virology , Cells, Cultured , Cellular Reprogramming/genetics , Cytokines/genetics , Cytokines/immunology , Female , Flow Cytometry , Gene Expression Profiling/methods , HIV-1/physiology , Host-Pathogen Interactions/immunology , Humans , Immunologic Memory/genetics , Lymphocyte Activation/genetics , Lymphocyte Activation/immunology , Male , Reverse Transcriptase Polymerase Chain Reaction , T-Lymphocytes, Cytotoxic/immunology , T-Lymphocytes, Cytotoxic/metabolism , Virus Latency/immunology , Virus Replication/immunologyABSTRACT
A stable latent reservoir for HIV-1 in resting CD4+ T cells is the principal barrier to a cure1-3. Curative strategies that target the reservoir are being tested4,5 and require accurate, scalable reservoir assays. The reservoir was defined with quantitative viral outgrowth assays for cells that release infectious virus after one round of T cell activation1. However, these quantitative outgrowth assays and newer assays for cells that produce viral RNA after activation6 may underestimate the reservoir size because one round of activation does not induce all proviruses7. Many studies rely on simple assays based on polymerase chain reaction to detect proviral DNA regardless of transcriptional status, but the clinical relevance of these assays is unclear, as the vast majority of proviruses are defective7-9. Here we describe a more accurate method of measuring the HIV-1 reservoir that separately quantifies intact and defective proviruses. We show that the dynamics of cells that carry intact and defective proviruses are different in vitro and in vivo. These findings have implications for targeting the intact proviruses that are a barrier to curing HIV infection.
Subject(s)
CD4-Positive T-Lymphocytes/virology , Carrier State/virology , Defective Viruses/isolation & purification , HIV Infections/virology , HIV-1/isolation & purification , Proviruses/isolation & purification , Virus Latency , CD4-Positive T-Lymphocytes/cytology , Carrier State/therapy , Cell Line , DNA, Viral/analysis , DNA, Viral/genetics , Defective Viruses/genetics , Defective Viruses/physiology , HIV Infections/therapy , HIV-1/genetics , HIV-1/physiology , Humans , Lymphocyte Activation , Polymerase Chain Reaction , Proviruses/genetics , Proviruses/physiologyABSTRACT
Charge density waves (CDWs) have been observed in nearly all families of copper-oxide superconductors. But the behavior of these phases across different families has been perplexing. In La-based cuprates, the CDW wavevector is an increasing function of doping, exhibiting the so-called Yamada behavior, while in Y- and Bi-based materials the behavior is the opposite. Here, we report a combined resonant soft X-ray scattering (RSXS) and neutron scattering study of charge and spin density waves in isotopically enriched La1.8−xEu0.2SrxCuO4 over a range of doping 0.07≤x≤0.20. We find that the CDW amplitude is temperature independent and develops well above experimentally accessible temperatures. Further, the CDW wavevector shows a nonmonotonic temperature dependence, exhibiting Yamada behavior at low temperature with a sudden change occurring near the spin ordering temperature. We describe these observations using a LandauGinzburg theory for an incommensurate CDW in a metallic system with a finite charge compressibility and spin-CDW coupling. Extrapolating to high temperature, where the CDW amplitude is small and spin order is absent, our analysis predicts a decreasing wavevector with doping, similar to Y and Bi cuprates. Our study suggests that CDW order in all families of cuprates forms by a common mechanism.
ABSTRACT
Neurons in the developing brain undergo extensive structural refinement as nascent circuits adopt their mature form. This physical transformation of neurons is facilitated by the engulfment and degradation of axonal branches and synapses by surrounding glial cells, including microglia and astrocytes. However, the small size of phagocytic organelles and the complex, highly ramified morphology of glia have made it difficult to define the contribution of these and other glial cell types to this crucial process. Here, we used large-scale, serial section transmission electron microscopy (TEM) with computational volume segmentation to reconstruct the complete 3D morphologies of distinct glial types in the mouse visual cortex, providing unprecedented resolution of their morphology and composition. Unexpectedly, we discovered that the fine processes of oligodendrocyte precursor cells (OPCs), a population of abundant, highly dynamic glial progenitors, frequently surrounded small branches of axons. Numerous phagosomes and phagolysosomes (PLs) containing fragments of axons and vesicular structures were present inside their processes, suggesting that OPCs engage in axon pruning. Single-nucleus RNA sequencing from the developing mouse cortex revealed that OPCs express key phagocytic genes at this stage, as well as neuronal transcripts, consistent with active axon engulfment. Although microglia are thought to be responsible for the majority of synaptic pruning and structural refinement, PLs were ten times more abundant in OPCs than in microglia at this stage, and these structures were markedly less abundant in newly generated oligodendrocytes, suggesting that OPCs contribute substantially to the refinement of neuronal circuits during cortical development.
Subject(s)
Neocortex , Oligodendrocyte Precursor Cells , Animals , Mice , Axons/metabolism , Oligodendroglia/metabolism , Neurons/metabolismABSTRACT
Tobacco mild green mosaic virus (TMGMV)-like nanocarriers were designed for gene delivery to plant cells. High aspect ratio TMGMVs were coated with a polycationic biopolymer, poly(allylamine) hydrochloride (PAH), to generate highly charged nanomaterials (TMGMV-PAH; 56.20 ± 4.7 mV) that efficiently load (1:6 TMGMV:DNA mass ratio) and deliver single-stranded and plasmid DNA to plant cells. The TMGMV-PAH were taken up through energy-independent mechanisms in Arabidopsis protoplasts. TMGMV-PAH delivered a plasmid DNA encoding a green fluorescent protein (GFP) to the protoplast nucleus (70% viability), as evidenced by GFP expression using confocal microscopy and Western blot analysis. TMGMV-PAH were inactivated (iTMGMV-PAH) using UV cross-linking to prevent systemic infection in intact plants. Inactivated iTMGMV-PAH-mediated pDNA delivery and gene expression of GFP in vivo was determined using confocal microscopy and RT-qPCR. Virus-like nanocarrier-mediated gene delivery can act as a facile and biocompatible tool for advancing genetic engineering in plants.
Subject(s)
Arabidopsis , Green Fluorescent Proteins , Arabidopsis/virology , Arabidopsis/genetics , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Gene Transfer Techniques , Plasmids/genetics , Polyamines/chemistry , Protoplasts/metabolism , Nanostructures/chemistry , DNA/chemistry , DNA/administration & dosageABSTRACT
BACKGROUND: Despite the well-established potent benefit of mechanical thrombectomy (MT) for large vessel occlusion (LVO) stroke, access to MT has not been studied globally. We conducted a worldwide survey of countries on 6 continents to define MT access (MTA), the disparities in MTA, and its determinants on a global scale. METHODS: Our survey was conducted in 75 countries through the Mission Thrombectomy 2020+ global network between November 22, 2020, and February 28, 2021. The primary end points were the current annual MTA, MT operator availability, and MT center availability. MTA was defined as the estimated proportion of patients with LVO receiving MT in a given region annually. The availability metrics were defined as ([current MT operators×50/current annual number of estimated thrombectomy-eligible LVOs]×100 = MT operator availability) and ([current MT centers×150/current annual number of estimated thrombectomy-eligible LVOs]×100= MT center availability). The metrics used optimal MT volume per operator as 50 and an optimal MT volume per center as 150. Multivariable-adjusted generalized linear models were used to evaluate factors associated with MTA. RESULTS: We received 887 responses from 67 countries. The median global MTA was 2.79% (interquartile range, 0.70-11.74). MTA was <1.0% for 18 (27%) countries and 0 for 7 (10%) countries. There was a 460-fold disparity between the highest and lowest nonzero MTA regions and low-income countries had 88% lower MTA compared with high-income countries. The global MT operator availability was 16.5% of optimal and the MT center availability was 20.8% of optimal. On multivariable regression, country income level (low or lower-middle versus high: odds ratio, 0.08 [95% CI, 0.04-0.12]), MT operator availability (odds ratio, 3.35 [95% CI, 2.07-5.42]), MT center availability (odds ratio, 2.86 [95% CI, 1.84-4.48]), and presence of prehospital acute stroke bypass protocol (odds ratio, 4.00 [95% CI, 1.70-9.42]) were significantly associated with increased odds of MTA. CONCLUSIONS: Access to MT on a global level is extremely low, with enormous disparities between countries by income level. The significant determinants of MT access are the country's per capita gross national income, prehospital LVO triage policy, and MT operator and center availability.
Subject(s)
Arterial Occlusive Diseases , Brain Ischemia , Ischemic Stroke , Stroke , Humans , Brain Ischemia/complications , Stroke/diagnosis , Stroke/epidemiology , Stroke/surgery , Thrombectomy , Triage , Treatment OutcomeABSTRACT
BACKGROUND: Recent large core trials have highlighted the effectiveness of mechanical thrombectomy (MT) in acute ischemic stroke with large vessel occlusion. Variable perfusion-imaging thresholds and poor Alberta Stroke Program Early Computed Tomography Score reliability underline the need for more standardized, quantitative ischemia measures for MT patient selection. We aimed to identify the computed tomography perfusion parameter most strongly associated with poor outcomes in patients with acute ischemic stroke-large vessel occlusion with significant ischemic cores. METHODS: In this study from 2 comprehensive stroke centers from 2 comprehensive stroke centers within the Johns Hopkins Medical Enterprise (Johns Hopkins Hospita-East Baltimore and Bayview Medical Campus) from July 29, 2019 to January 29, 2023 in a continuously maintained database, we included patients with acute ischemic stroke-large vessel occlusion with ischemic core volumes defined as relative cerebral blood flow <30% and ≥50 mL on computed tomography perfusion or Alberta Stroke Program Early Computed Tomography Score <6. We used receiver operating characteristics to find the optimal cutoff for parameters like cerebral blood volume (CBV) <34%, 38%, 42%, and relative cerebral blood flow >20%, 30%, 34%, 38%, and time-to-maximum >4, 6, 8, and 10 seconds. The primary outcome was unfavorable outcomes (90-day modified Rankin Scale score 4-6). Multivariable models were adjusted for age, sex, diabetes, baseline National Institutes of Health Stroke Scale, intravenous thrombolysis, and MT. RESULTS: We identified 59 patients with large ischemic cores. A receiver operating characteristic curve analysis showed that CBV<42% ≥68 mL is associated with unfavorable outcomes (90-day modified Rankin Scale score 4-6) with an area under the curve of 0.90 (95% CI, 0.82-0.99) in the total and MT-only cohorts. Dichotomizing at this CBV threshold, patients in the ≥68 mL group exhibited significantly higher relative cerebral blood flow, time-to-maximum >8 and 10 seconds volumes, higher CBV volumes, higher HIR, and lower CBV index. The multivariable model incorporating CBV<42% ≥68 mL predicted poor outcomes robustly in both cohorts (area under the curve for MT-only subgroup was 0.87 [95% CI, 0.75-1.00]). CONCLUSIONS: CBV<42% ≥68 mL most effectively forecasts poor outcomes in patients with large-core stroke, confirming its value alongside other parameters like time-to-maximum in managing acute ischemic stroke-large vessel occlusion.
ABSTRACT
Chromium and arsenic are two of the most problematic water pollutants due to their high toxicity and prevalence in various water streams. While adsorption and ion-exchange processes have been applied for the efficient removal of numerous toxic contaminants, including heavy metals, from water, these technologies display relatively low overall performances and stabilities for the remediation of chromium and arsenic oxyanions. This work presents the use of polyol-functionalized porous aromatic framework (PAF) adsorbent materials that use chelation, ion-exchange, redox activity, and hydrogen-bonding interactions for the highly selective capture of chromium and arsenic from water. The chromium and arsenic binding mechanisms within these materials are probed using an array of characterization techniques, including X-ray absorption and X-ray photoelectron spectroscopies. Adsorption studies reveal that the functionalized porous aromatic frameworks (PAFs) achieve selective, near-instantaneous (reaching equilibrium capacity within 10 s), and high-capacity (2.5 mmol/g) binding performances owing to their targeted chemistries, high porosities, and high functional group loadings. Cycling tests further demonstrate that the top-performing PAF material can be recycled using mild acid and base washes without any measurable performance loss over at least ten adsorption-desorption cycles. Finally, we establish chemical design principles enabling the selective removal of chromium, arsenic, and boron from water. To achieve this, we show that PAFs appended with analogous binding groups exhibit differences in adsorption behavior, revealing the importance of binding group length and chemical identity.
ABSTRACT
Cystic fibrosis-related diabetes (CFRD) affects 40%-50% of adults with CF and is associated with a decline in respiratory health. The microbial flora of the lung is known to change with the development of CF disease, but how CFRD affects the microbiome has not been described. We analyzed the microbiome in sputa from 14 people with CF, 14 with CFRD, and two who were classed as pre-CFRD by extracting DNA and amplifying the variable V3-V4 region of the microbial 16S ribosomal RNA gene by PCR. Sequences were analyzed and sources were identified to genus level. We found that the α-diversity of the microbiome using Shannon's diversity index was increased in CFRD compared with CF. Bray Curtis dissimilarity analysis showed that there was separation of the microbiomes in CF and CFRD sputa. The most abundant phyla identified in the sputum samples were Firmicutes and Proteobacteria, Actinobacteriota and Bacteroidota, and the ratio of Firmicutes/Bacteroidota was reduced in CFRD compared with CF. Pseudomonas, Azhorizophilus, Porphyromonas, and Actinobacillus were more abundant in CFRD compared with CF, whereas Staphylococcus was less abundant. The relative abundance of these genera did not correlate with age; some correlated with a decline in FEV1/FVC but all correlated with hemoglobin A1C (HbA1c) indicating that development of CFRD mediates further changes to the respiratory microbiome in CF.NEW & NOTEWORTHY Cystic fibrosis-related diabetes (CFRD) is associated with a decline in respiratory health. We show for the first time that there was a change in the sputum microbiome of people with CFRD compared with CF that correlated with markers of raised blood glucose.
Subject(s)
Cystic Fibrosis , Diabetes Mellitus , Microbiota , Adult , Humans , Cystic Fibrosis/complications , Cystic Fibrosis/microbiology , Sputum , Lung/microbiologyABSTRACT
YejABEF is an ATP-binding cassette transporter that is implicated in the sensitivity of Escherichia coli to anti-microbial peptides, the best-characterized example being microcin C, a peptide-nucleotide antibiotic that targets aspartyl-tRNA synthetase. Here the structure of the extracellular solute binding protein, YejA, has been determined, revealing an oligopeptide-binding protein fold enclosing a ligand-binding pocket larger than those of other peptide-binding proteins of known structure. Prominent electron density in this cavity defines an undecapeptide sequence LGEPRYAFNFN, an observation that is confirmed by mass spectrometry. In the structure, the peptide interactions with the protein are mediated by main chain hydrogen bonds with the exception of Arg5 whose guanidinium side chain makes a set of defining polar interactions with four YejA residues. More detailed characterization of purified recombinant YejA, by a combination of ESI and MALDI-mass spectrometry as well as thermal shift assays, reveals a set of YejA complexes containing overlapping peptides 10-19 residues in length. All contain the sequence LGEPRYAFN. Curiously, these peptides correspond to residues 8-26 of the mature YejA protein, which belong to a unique N-terminal extension that distinguishes YejA from other cluster C oligopeptide binding proteins of known structure. This 35-residue extension is well-ordered and packs across the surface of the protein. The undecapeptide ligand occupies only a fraction of the enclosed pocket volume suggesting the possibility that much larger peptides or peptide conjugates could be accommodated, though thermal shift assays of YejA binding to antimicrobial peptides and peptides unrelated to LGEPRYAFNFN have not provided evidence of binding. While the physiological significance of this 'auto-binding' is not clear, the experimental data suggest that it is not an artefact of the crystallization process and that it may have a function in the sensing of periplasmic or membrane stress.
Subject(s)
ATP-Binding Cassette Transporters , Membrane Transport Proteins , Peptides , Ligands , Peptides/metabolism , ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/metabolism , Oligopeptides , Escherichia coli/metabolism , Protein BindingABSTRACT
Background The combination of intravenous thrombolysis (IVT) with mechanical thrombectomy (MT) may have clinical benefits for patients with medium vessel occlusion. Purpose To examine whether MT combined with IVT is associated with different outcomes than MT alone in patients with acute ischemic stroke (AIS) and medium vessel occlusion. Materials and Methods This retrospective study included consecutive adult patients with AIS and medium vessel occlusion treated with MT or MT with IVT at 37 academic centers in North America, Asia, and Europe. Data were collected from September 2017 to July 2021. Propensity score matching was performed to reduce confounding. Univariable and multivariable logistic regression analyses were performed to test the association between the addition of IVT treatment and different functional and safety outcomes. Results After propensity score matching, 670 patients (median age, 75 years [IQR, 64-82 years]; 356 female) were included in the analysis; 335 underwent MT alone and 335 underwent MT with IVT. Median onset to puncture (350 vs 210 minutes, P < .001) and onset to recanalization (397 vs 273 minutes, P < .001) times were higher in the MT group than the MT with IVT group, respectively. In the univariable regression analysis, the addition of IVT was associated with higher odds of a modified Rankin Scale (mRS) score 0-2 (odds ratio [OR], 1.44; 95% CI: 1.06, 1.96; P = .019); however, this association was not observed in the multivariable analysis (OR, 1.37; 95% CI: 0.99, 1.89; P = .054). In the multivariable analysis, the addition of IVT also showed no evidence of an association with the odds of first-pass effect (OR, 1.27; 95% CI: 0.9, 1.79; P = .17), Thrombolysis in Cerebral Infarction grades 2b-3 (OR, 1.64; 95% CI: 0.99, 2.73; P = .055), mRS scores 0-1 (OR, 1.27; 95% CI: 0.91, 1.76; P = .16), mortality (OR, 0.78; 95% CI: 0.49, 1.24; P = .29), or intracranial hemorrhage (OR, 1.25; 95% CI: 0.88, 1.76; P = .21). Conclusion Adjunctive IVT may not provide benefit to MT in patients with AIS caused by distal and medium vessel occlusion. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Wojak in this issue.
Subject(s)
Ischemic Stroke , Thrombectomy , Thrombolytic Therapy , Humans , Female , Male , Aged , Retrospective Studies , Thrombectomy/methods , Ischemic Stroke/diagnostic imaging , Ischemic Stroke/surgery , Ischemic Stroke/therapy , Middle Aged , Aged, 80 and over , Thrombolytic Therapy/methods , Combined Modality Therapy , Treatment Outcome , Fibrinolytic Agents/therapeutic use , Fibrinolytic Agents/administration & dosage , Propensity ScoreABSTRACT
Cellular antiviral factors that recognize viral nucleic acid can inhibit virus replication. These include the zinc finger antiviral protein (ZAP), which recognizes high CpG dinucleotide content in viral RNA. Here, we investigated the ability of ZAP to inhibit the replication of human cytomegalovirus (HCMV). Depletion of ZAP or its cofactor KHNYN increased the titer of the high-passage HCMV strain AD169 but had little effect on the titer of the low-passage strain Merlin. We found no obvious difference in expression of several viral proteins between AD169 and Merlin in ZAP knockdown cells, but observed a larger increase in infectious virus in AD169 compared to Merlin in the absence of ZAP, suggesting that ZAP inhibited events late in AD169 replication. In addition, there was no clear difference in the CpG abundance of AD169 and Merlin RNAs, indicating that genomic content of the two virus strains was unlikely to be responsible for differences in their sensitivity to ZAP. Instead, we observed less ZAP expression in Merlin-infected cells late in replication compared to AD169-infected cells, which may be related to different abilities of the two virus strains to regulate interferon signaling. Therefore, there are strain-dependent differences in the sensitivity of HCMV to ZAP, and the ability of low-passage HCMV strain Merlin to evade inhibition by ZAP is likely related to its ability to regulate interferon signaling, not the CpG content of RNAs produced from its genome. IMPORTANCE Determining the function of cellular antiviral factors can inform our understanding of virus replication. The zinc finger antiviral protein (ZAP) can inhibit the replication of diverse viruses. Here, we examined ZAP interaction with the DNA virus human cytomegalovirus (HCMV). We found HCMV strain-dependent differences in the ability of ZAP to influence HCMV replication, which may be related to the interaction of HCMV strains with the type I interferon system. These observations affect our current understanding of how ZAP restricts HCMV and how HCMV interacts with the type I interferon system.