Search bioRxiv⌕ Search

Biology subjects

Yin, B.

Publications and source records attributed to Yin, B..

At least 19 recordsLinked to original sources

History-structured forecasting of rewarded give-up behavior in a rodent metacognition task

Longitudinal animal experiments generate behavior that is individual, history-dependent, and sometimes affected by ordinary procedural irregularities, yet analyses commonly reduce such records to pooled averages or synchronous trial-level explanations. We introduce history-structured forecasting as an auditable framework for determining whether an animals own preceding behavior carries predictive information beyond current-trial context. We applied the framework to 213,990 events from rats performing an auditory duration-discrimination task, using leakage-safe chronological forward-chaining, explicit trivial baselines, and controls that reset, exchange, or disrupt behavioral history. A transparent gradient-boosted model achieved 51.7% four-class accuracy, exceeding last-action persistence (40.9%) and prefix-derived subject-modal prediction (37.2%); decline-class AUPRC was 0.525 against a prevalence baseline of 0.303. Validation showed that the predictive advantage depended predominantly on each animals short-range sequential action history rather than group-level history, subject identity alone, or reward/correctness features, and strengthened on genuine choice trials. Forecasting remained informative across all 23 labeled animals, including six with recoverable records affected by incorrect training programming. These results revise the interpretation of rewarded give-up behavior while demonstrating how recoverable irregular records can be retained in transparent robustness analyses. History-structured forecasting offers a reusable open-science strategy for extracting reproducible evidence from imperfect longitudinal animal records without creating an artificially clean cohort.

animal behavior and cognition↗

A canonical four-state macro-architecture governs multimodal fear-goal arbitration across learning and relapse

When defensive behavior declines, has the individual recovered? Addressing this translational question requires testing whether exploration and goal pursuit also return, and whether those gains survive time and context. We adapted rat fear-conditioning, extinction, delay, and contextual relapse paradigms to this problem. Male rats first explored the chambers under safer conditions and learned to press for food; aversive conditioning then reorganized the repertoire around danger. Extending tri-reference-point (TRP) theory from risky choice, we framed the repertoire around danger, the current condition, and goals. Across 47,004 five-second windows from 29 animals and 213 subject-sessions, we aligned freezing, 22- and 50-kHz calls, and lever presses. Subject-grouped, discrete-aware validation selected a diagonal Gaussian hidden Markov model at theory-guided K=4, decoding recurrent Fear/Danger, Quiescent, Exploratory, and Goal-directed modes. K=8 predicted held-out data better and subdivided these functional regions. Conditioning shifted occupancy from Exploratory toward Fear/Danger. By the final decile of initial extinction, Fear/Danger had fallen to 2.7%, yet Quiescent occupied 95.8%, with Exploratory at 0.6% and Goal-directed at 1.0%: fear reduction without broader functional restoration. Across related cohorts, later tests revealed exploratory-rich and renewed-defense trajectories. Goal-to-Fear transitions were depleted under two null models, and Fear/Danger occupancy was associated with fecal boli after session adjustment (bias-reduced p=0.036). Count-tailored models preserved temporal dependence but regrouped behavior, showing that state identity depends partly on representation. Together, multimodal measurement, TRP-derived landmarks, and temporal modeling make functional recovery testable as the history-dependent restoration of an individual's behavioral repertoire, not merely the suppression of defense.

animal behavior and cognition↗

Disease-specific differences in particulate matter handling drive pathogenic responses in human derived nasal epithelial cells

BackgroundParticulate matter (PM) exposure is associated with increased risk and exacerbation of chronic rhinosinusitis (CRS), yet underlying mechanisms remain poorly understood. ObjectiveTo define the epithelial mechanisms by which PM exposure promotes and exacerbates CRS, with a focus on epithelial remodeling, inflammation, barrier dysfunction, and cellular uptake of PM. MethodsHuman nasal epithelial cells obtained from ethmoid tissue of CRS (n = 5) and control donors (n = 4) were cultured at an air-liquid interface and exposed to PM. Single-cell RNA sequencing was performed to characterize PM-induced cellular and transcriptional changes. Protein expression, epithelial barrier integrity, cell death, and intracellular PM uptake were evaluated using biochemical, imaging, and ultrastructural approaches. ResultsUnsupervised clustering identified seven epithelial cell populations. Gene set analysis revealed baseline enrichment of inflammatory and keratinization pathways and reduced ciliogenesis in CRS compared with controls. Although PM induced inflammation and squamous differentiation in controls, the pathogenic responses were significantly amplified in CRS, including uniquely enhanced IL-1 signaling. Transcriptional changes were validated by ELISA, transepithelial electrical resistance, and immunofluorescence, demonstrating increased inflammation, epithelial barrier disruption, and cell death following PM exposure. Transmission electron microscopy revealed increased intracellular PM within membrane-bound organelles. Pre-treatment with an endocytosis inhibitor rescued PM-induced epithelial barrier dysfunction and inflammation. ConclusionCRS epithelium exhibits baseline dysfunction that may predispose it to environmental injury. PM exposure both induces CRS-like epithelial changes in controls and exacerbates disease-associated phenotypes. Key MessagesO_LICompared to controls, CRS nasal epithelium exhibits baseline inflammatory, keratinization, and ciliogenesis abnormalities. C_LIO_LIParticulate matter induces inflammation and squamous differentiation, while amplifying epithelial injury that is more robust in CRS epithelium compared to controls. C_LIO_LIInhibition of dynamin-dependent endocytosis rescues PM-induced epithelial barrier leakiness and inflammation, implicating intracellular particulate matter uptake in disease pathogenesis. C_LI Capsule SummaryParticulate matter induces CRS-like epithelial remodeling in controls and exacerbates inflammation and epithelial barrier dysfunction in CRS nasal epithelium, which can be rescued with endocytosis inhibition. This suggests a mechanistic link between baseline CRS vulnerability, intracellular uptake of particulate matter, and disease pathogenesis.

cell biology↗

Multi-Omics Reveals Activated Fibroblasts with Dual Functional Roles in Repair and Negative Barrier in the CD8+ T Cell Cytotoxic Niche for Lung Cancer Neoadjuvant Therapy

A major challenge in elucidating immune activation and tolerance is that single-omics technologies are inherently limited. Since single-cell transcriptomics lacks spatial information and spatial transcriptomics lacks resolution or depth, neither can adequately model the multidimensional tumor immune microenvironment (TiME) features. We present NICHE (Niche Integrated Cellular Heterogeneity Elucidator), an integrative multi-omics framework. By aligning physical cell-cell interactions with single-cell ligand-receptor (L-R) expression, NICHE leverages single-cell transcriptomics, spatial proteomics, and AI modeling to systematically decode the composition, spatial interactions, and communications within immune functional niches. To validate NICHEs capabilities, we applied it to human tonsil tissue. The framework successfully identified key structural and functional units and deeply elucidated the cell-cell interactions and molecular crosstalk within them. Furthermore, these results were validated through orthogonal methods, including single-cell spatial transcriptomics and multiplexed immunofluorescence, which confirmed the accuracy and reproducibility of our analyses. In non-small cell lung cancer (NSCLC) patients undergoing neoadjuvant immunotherapy, CD8+ T cell cytotoxic niches mediate tumor clearance with variable outcomes, to define the cellular and molecular drivers behind this functional spectrum, we utilized NICHE to analyze the TiME from patients with complete versus partial pathological response, both pre- and post-treatment. We found that neoadjuvant immunotherapy may induce the activation of CXCL12+, NECTIN2+, POSTN+, and COL6A1+ fibroblasts through the activation of cytotoxic T cells. Paradoxically, these fibroblasts support tissue repair but also establish an immunosuppressive niche that protects residual tumor cells, ultimately attenuating treatment efficacy. Our work establishes a multidimensional framework for dissecting dynamic immune activity, with direct implications for understanding tumor immunology and identifying novel therapeutic targets.

immunology↗

A Novel 3D Visualization Method in Mice Identifies the Periportal Lamellar Complex (PLC) as a Key Regulator of Hepatic Ductal and Neuronal Branching Morphogenesis

The liver is a complex organ responsible for multiple functions, including metabolism, energy storage, detoxification, bile secretion, and immune regulation. Its highly organized vascular system plays a crucial role in maintaining functional zonation and tissue homeostasis. Within the liver, the hepatic artery, portal vein, hepatic vein, bile duct, and nerve networks intertwine to form an intricate three-dimensional architecture; however, traditional two-dimensional imaging fails to reveal their true spatial relationships, and current three-dimensional imaging methods remain insufficient to capture fine structural details. To achieve comprehensive visualization of these multi-ductal systems, we established a high-resolution three-dimensional imaging platform that combines multicolor perfusion of metallic compound nanoparticles (MCNPs) with an optimized tissue-clearing protocol (Liver-CUBIC), enabling simultaneous 3D reconstruction of the portal vein, hepatic artery, bile duct, and hepatic vein in mouse livers. Based on these data, we identified and defined a previously unrecognized structure located in the outer layer of the portal vein, termed the Periportal Lamellar Complex (PLC). The PLC encircles the portal vein between the vascular endothelium and the perisinusoidal region, exhibits low-permeability barrier characteristics, and contains a distinctive population of CD34Sca-1 endothelial cells. During liver fibrosis, the PLC extends from the portal vein toward the hepatic lobule, forming a structural scaffold that guides bile duct and nerve migration.

developmental biology↗

VitisC: Visualizing interested target via integrated scaffold of cytoophidium

Cryo-electron microscopy (cryo-EM) single-particle analysis has become a widely used technique for high-resolution structural determination of biological macromolecules and complexes. However, the determination of the structure of small molecule proteins remains a limitation of this technology. To address this issue, here we develop a novel approach termed Visualizing interested target via integrated scaffold of cytoophidium (VitisC). We use a filamentous structure formed by Escherichia coli CTP synthase (CTPS) as the scaffold, termed the scaffold of cytoophidium. Through artificial design and modification, small proteins can be attached to this symmetrical scaffold, which is very suitable for cryo-EM imaging. The formation conditions for stable filament structures of the fusion protein are optimized in vitro, and the three-dimensional structure of the fusion protein is reconstructed using cryo-EM single-particle analysis, achieving an overall resolution of 3.39 [A]. Therefore, cryo-EM is successfully applied to visualize small proteins. VitisC not only demonstrates the feasibility of employing cytoophidia as scaffolds, but also provides an approach for high-resolution structural analysis of small proteins using Cryo-EM.

biochemistry↗

Pipeline for Assessing Tumor Immune Status Using Superplex Immunostaining and Spatial Immune Interaction Analysis

The characteristics of the tumor microenvironment (TME) are closely linked to tumor progression and treatment response. The TME comprises various cell types, their spatial distribution, cell-cell interactions, and their organization into cellular niches or neighborhoods. To capture this complexity, several spatial profiling technologies have been developed. However, challenges such as low throughput, high costs, and complicated data analysis have limited their widespread use in immune research. In this study, we introduce the Cyclic-multiplex TSA (CmTSA) staining platform, a high-throughput superplex staining technology based on tyramide signal amplification (TSA) immunostaining combined with an efficient fluorophore recycling method. The CmTSA platform allows for the labeling of 30-60 antigens across multiple parallel formalin-fixed paraffin-embedded (FFPE) slides. Furthermore, the automated CmTSA workflow requires only standard histological equipment and conventional immunohistochemistry (IHC) primary antibodies (Abs), significantly reducing costs. While the superplex images produced contain extensive multidimensional information, extracting the spatial features of the TME from raw pixel data can be challenging. To address this, we present a computer vision-based analysis pipeline, which begins with deep learning-based algorithms to segment individual cells and identify cell types based on defined annotation rules. It then evaluates the spatial distribution tendencies of each cell type, the interaction intensity between paired cells, and the multicellular functional niches. This comprehensive approach enables researchers to visualize and quantify the types, states, and levels of immune activities within the TME effectively, advancing tumor immunology research and precision immune medicine.

cancer biology↗

Molecular Basis for RNA Cytidine Acetylation by NAT10

Human NAT10 acetylates the N4 position of cytidine in RNA, predominantly on rRNA and tRNA, to facilitate ribosome biogenesis and protein translation. NAT10 has been proposed as a therapeutic target in cancers as well as aging-associated pathologies such as Hutchinson-Gilford Progeria Syndrome (HGPS). The [~]120 kDa NAT10 protein uses its acetyl-CoA-dependent acetyltransferase, ATP-dependent helicase, and RNA binding domains in concert to mediate RNA-specific N4-cytidine acetylation. While the biochemical activity of NAT10 is well known, the molecular basis for catalysis of eukaryotic RNA acetylation remains relatively undefined. To provide molecular insights into the RNA-specific acetylation by NAT10, we determined the single particle cryo-EM structures of Chaetomium thermophilum NAT10 (CtNAT10) bound to a bisubstrate cytidine-CoA probe with and without ADP. The structures reveal that NAT10 forms a symmetrical heart-shaped dimer with conserved functional domains surrounding the acetyltransferase active sites harboring the cytidine-CoA probe. Structure-based mutagenesis with analysis of mutants in vitro supports the catalytic role of two conserved active site residues (His548 and Tyr549 in CtNAT10), and two basic patches, both proximal and distal to the active site for RNA-specific acetylation. Yeast complementation analyses and senescence assays in human cells also implicates NAT10 catalytic activity in yeast thermoadaptation and cellular senescence. Comparison of the NAT10 structure to protein lysine and N-terminal acetyltransferase enzymes reveals an unusually open active site suggesting that these enzymes have been evolutionarily tailored for RNA recognition and cytidine-specific acetylation.

biophysics↗

The kinematics and aerodynamics of hinged wing of honeybees during takeoff

In this study, we utilize a high-speed camera array to meticulously capture the intricate wing kinematics of honeybees during free voluntary takeoffs. This allows us to investigate the variation in kinematic parameters over time. According to the variation of Euler angles, the takeoff process can be categorized into three stages: initial, adjusting, and stable. Our analysis reveals that honeybees typically execute at least 15 wingbeats before taking off, with wing stroke amplitudes exceeding 100 degrees and wingbeat frequencies ranging from 180 to 260 Hz. Significantly, the hinged wing mechanism, connecting the forewing and hindwing via hamuli, undergoes considerable chordwise deformation during this process, with the angle between the fore- and hind-wings surpassing 50 degrees. Notably, the forewing and hindwing maintain a positive camber throughout the wingbeat cycle during takeoff, contributing to the enhanced thrust generation instead of lift, comparing to the flat wings. The positive camber can be passively formed at beginning and ending of each half stroke, but should be actively maintained around middle half-stroke.This study provides valuable insights for aeronautical engineers in the design of flapping wing micro air vehicles, specifically in the effective implementation of hinged wings inspired by the wing motion of honeybees.

biophysics↗

Cell Type Specific Responses of the Endoplasmic Reticulum Dynamics to Environmental Stress

To overcome the challenge of balancing imaging speecd and resolution, which currently limits the accurate identification of structural and dynamic changes in the study of endoplasmic reticulum (ER) in plant cells. This research employs structured illumination microscopy techniques to achieve super-resolution real-time imaging of the ER in live Arabidopsis materials. Additionally, a self-supervised denoising framework (Blind2Unblind) was optimized to further enhance the signal-to-noise ratio of rapid microscopic imaging. Based on the images with high quality, a method for quantitative analysis of ER structures using time-lapse images is developed. Moreover, detections of changes in ER structures under environmental stress are conducted to verify the effectiveness of the method. Moreover, correlation analyses of various parameters indicate a significant positive correlation between the area and length of tubular ER with the number of growth tips and tricellular junctions, while the area of ER cisternae and bulk flow exhibits a significant negative correlation with the area and length of tubules. The super-resolution imaging and dynamic analysis method developed in this study will provide new technical approaches for further elucidating the function and regulatory mechanisms of the plant ER.

plant biology↗

Lung and liver editing by lipid nanoparticle delivery of a stable CRISPR-Cas9 RNP

Lipid nanoparticle (LNP) delivery of CRISPR ribonucleoproteins (RNPs) has the potential to enable high-efficiency in vivo genome editing with low toxicity and an easily manufactured technology, if RNP efficacy can be maintained during LNP production. In this study, we engineered a thermostable Cas9 from Geobacillus stearothermophilus (GeoCas9) using directed evolution to generate iGeoCas9 evolved variants capable of robust genome editing of cells and organs. iGeoCas9s were significantly better at editing cells than wild-type GeoCas9, with genome editing levels >100X greater than those induced by the native GeoCas9 enzyme. Furthermore, iGeoCas9 RNP:LNP complexes edited a variety of cell lines and induced homology-directed repair (HDR) in cells receiving co-delivered single-stranded DNA (ssDNA) templates. Using tissue-selective LNP formulations, we observed genome editing of 35-56% efficiency in the liver or lungs of mice that received intravenous injections of iGeoCas9 RNP:LNPs. In particular, iGeoCas9 complexed to acid-degradable LNPs edited lung tissue in vivo with an average of 35% efficiency, a significant improvement over editing efficiencies observed previously using viral or non-viral delivery strategies. These results show that thermostable Cas9 RNP:LNP complexes are a powerful alternative to mRNA:LNP delivery vehicles, expanding the therapeutic potential of genome editing.

bioengineering↗

Inducible nitric oxide synthase (iNOS) is necessary for GBP-mediated T. gondii restriction in murine macrophages via vacuole nitration and intravacuolar network collapse

Toxoplasma gondii is an obligate intracellular, protozoan pathogen of rodents and humans. T. gondiis ability to grow within cells and evade cell-autonomous immunity depends on the integrity of the parasitophorous vacuole (PV). Interferon-inducible guanylate binding proteins (GBPs) are central mediators of T. gondii clearance, however, the precise mechanism linking GBP recruitment to the PV and T. gondii restriction is not clear. This knowledge gap is linked to heterogenous GBP-targeting across a population of vacuoles and the lack of tools to selectively purify the intact PV. To identify mediators of parasite clearance associated with GBP2-positive vacuoles, we employed a novel protein discovery tool automated spatially targeted optical micro proteomics (autoSTOMP). This approach identified inducible nitric oxide synthetase (iNOS) enriched at levels similar to the GBPs in infected bone marrow-derived myeloid cells. iNOS expression on myeloid cells was necessary for mice to control T. gondii growth in vivo and survive acute infection. T. gondii infection of IFN{gamma}-primed macrophage was sufficient to robustly induce iNOS expression. iNOS restricted T. gondii infection through nitric oxide synthesis rather than arginine depletion, leading to robust and selective nitration of the PV. Optimal parasite restriction by iNOS and vacuole nitration depended on the chromosome 3 GBPs. Notably, GBP2 recruitment and ruffling of the PV membrane occurred in iNOS knockouts, however, these vacuoles contained dividing parasites. iNOS activity was necessary for the collapse of the intravacuolar network of nanotubular membranes which connects parasites to each other and the host cytosol. Based on these data we conclude reactive nitrogen species generated by iNOS cooperate with the chromosome 3 GBPs to target distinct biology of the PV that are necessary for optimal parasite clearance in murine myeloid cells.

immunology↗

22kHz Ultrasonic Vocalizations and Body Freezing May Represent Two Systems of Fear in Rodent Fear Conditioning Paradigms

The "two-system" framework of fear proposed by LeDoux and Pine (2016) sparked a discussion on the understanding of fear, prompting a reevaluation of rodent fear conditioning studies. We propose that 22kHz ultrasonic vocalizations (USV) may symbolize the subjective negative emotional states in rats. To evaluate this, we designed a series of fear conditioning experiments with varied parameters, comparing the expression of 22kHz USV and body freezing - a traditional fear index. These expressions were further assessed in fear generalization tests. Our findings suggest a distinct separation between body freezing and 22kHz vocalizations in fear conditioning under different conditions. The results indicate that 22kHz USV may more accurately signify the subjective state of fear, whereas body freezing may denote an automatic defensive response in rats. Consequently, we posit that the two-system fear framework may extend to rodent fear conditioning paradigms. Therefore, researchers should place greater emphasis on 22kHz vocalizations when investigating the subjective state of fear.

animal behavior and cognition↗

Host and transmission route of Enterocytozoon hepatopenaei (EHP) from dragonfly to shrimp

Enterocytozoon hepatopenaei (EHP) is a shrimp pathogen that causes huge economic losses. In the present study, the hosts of EHP were investigated using polymerase chain reaction (PCR) in an aquaculture farm located in Maoming, China. EHP was detected in Litopenaeus vannamei, Penaeus monodon, crab, false mussel, and three dragonfly species (Anax parthenope, Pantala flavescens, and Ischnura senegalensis). In the histopathological examination using hematoxylin-eosin staining, EHP spores were found in nymphs and adult dragonflies naturally infected with EHP that were collected from the shrimp farm. Fluorescence in situ hybridization results showed a positive signal for EHP infection in the fat body of dragonfly nymphs. Immature and mature microsporidian spores and late sporogonial plasmodium were observed in the cytoplasm of dragonfly nymphs using transmission electron microscopy. The transmission of EHP from shrimp to dragonfly nymphs was confirmed via cohabitation challenge experiments in which EHP-free dragonfly nymphs were cohabited with EHP-infected shrimp, and the transmission of EHP from dragonfly nymphs to shrimp was demonstrated via the cohabitation of EHP-infected dragonfly nymphs with EHP-free shrimp and oral administration challenge experiments. This study confirms that dragonflies can act as natural EHP hosts, and a novel EHP horizontal transmission route exists between dragonflies and shrimp. Author summaryTo the authors knowledge, this study presents the first report of microsporidia (EHP) infecting both crustaceans and insects (A. parthenope, P. flavescens, and I. senegalensis). The horizontal transmission of EHP between dragonfly nymphs and shrimp was confirmed through cohabitation and oral administration challenge experiments. EHP has become a globally significant threat to shrimp aquaculture. The findings of the present study will help to design prevention strategies, such as the use of nets to prevent dragonflies from entering shrimp ponds.

microbiology↗

An Empirical Study on the Motivation of Helping Behavior in Rats

Using rodent models to explore the motivation of helping behaviors has become a new trend in recent years. Empathy, the alleviation of personal distress, and desire for social contact have been considered motivations for rodents to engage in helping behaviors. We used 108 Sprague-Dawley rats as subjects and modified the two-chambered helping behavior experimental setup in Carvalheiro and colleagues study to explore the main motivations of helping behavior in rodents through three experiments. The findings suggest that (1) the desire for social contact and pursuit of an interesting environment are the primary motivations for helping behavior, regardless of the presence of a dark chamber, and (2) the alleviation of personal distress and prior experience of social contact rather than distress experience contribute to the onset and persistence of helping behavior.

animal behavior and cognition↗

Lipid Driven Inter-leaflet Coupling of Plasma Membrane Order Regulates FcεRI Signaling in Mast Cells

Engagement of high affinity immunoglobulin E (IgE) receptor Fc{varepsilon}RI with extracellular, multivalent antigen (Ag) stabilizes co-existing ordered and disordered phases in the inner leaflet of the plasma membrane. This optimally controls biochemical interactions between signaling components required for transmembrane (TM) signaling in mast cells. The biophysical organization of the resting inner leaflet is poised to respond appropriately to this extracellular stimulation. The resting inner leaflet is generally less ordered than the outer leaflet, with a lipid composition that does not spontaneously phase separate in model membranes. We proposed that coupling between the two leaflets mediates separation into different phase-like domains in the inner leaflet. To test this hypothesis in live cells, we first established a straightforward approach to evaluate changes in membrane order due to inter-leaflet coupling by measuring inner leaflet diffusion of phase-specific lipid probes with Imaging Fluorescence Correlation Spectroscopy (ImFCS) before and after methyl--cyclodextrin (mCD)-catalyzed exchange of outer leaflet lipids (LEX) with exogenous order- or disorder-promoting phospholipids. We examined the functional impact of LEX by monitoring two Ag-stimulated cellular responses, namely early-stage recruitment of Syk kinase to the inner leaflet and late-stage exocytosis of secretory granules (degranulation). Based on changes in probe diffusion, we observed global increase or decrease of inner leaflet order when outer leaflet is exchanged with order or disorder promoting lipids, respectively, in unstimulated cells. Furthermore, the degree of stimulated Syk recruitment and degranulation correlates with the inner leaflet order of the resting cells, which was varied using LEX. Overall, combined LEX and ImFCS platform provides strong evidence of lipid-based control of stimulated TM signaling in live mast cells. In addition, our functional results imply that resting-state lipid composition and ordering of the outer leaflet sets the ordering of the inner leaflet, likely via interleaflet coupling, and correspondingly modulates TM signaling initiated by antigen-activated IgE-Fc{varepsilon}RI. STATEMENT OF SIGNIFICANCECoupling between plasma membrane leaflets, which are biochemically and biophysically asymmetric, results in a steady-state membrane organization that is thought to play fundamental roles in cellular functions. Here, we present a straightforward assay built around mCD-catalyzed lipid exchange (LEX) and Imaging Fluorescence Correlation Spectroscopy (ImFCS) to quantitatively characterize a novel, lipid-driven, interleaflet coupling mechanism and its functional impact in live mast cells. We showed that elevation of outer leaflet lipid order induces ordering throughout the inner leaflet in resting cells. This ordering enhances protein-based reactions during Ag-stimulated Fc{varepsilon}RI signaling and consequent cellular response. Overall, we provide a compelling evidence of functional relevance of plasma membrane organizational heterogeneity driven by lipid-based interleaflet coupling.

biophysics↗

Non-viral gene editing in utero with lipid nanoparticles complexed to mRNA

Nanoparticle-based drug delivery systems have the potential to revolutionize medicine but their low vascular permeability and rapid clearance by phagocytic cells have limited their medical impact. Nanoparticles delivered at the in utero stage have the potential to overcome these key limitations, due to the high rate of angiogenesis and cell division in fetal tissue, and the under-developed immune system. However, very little is known about nanoparticle drug delivery at the fetal stage of development. In this report, using Ai9 CRE reporter mice, we demonstrate that lipid nanoparticle (LNP) mRNA complexes can deliver mRNA for gene editing enzymes in utero after an intrahepatic injection, and can access and edit major organs, such as the heart, the liver, kidneys, lungs and the gastrointestinal tract with remarkable efficiency and low toxicity. In addition, we show here that Cas9 mRNA and sgRNA complexed to LNPs were able to edit the fetal organs in utero after an intrahepatic injection. These experiments demonstrate the possibility of non-viral delivery of gene editing enzymes in utero and nanoparticle drug delivery has great potential for delivering macromolecules to organs outside of the liver in utero, which provides a promising strategy for treating a wide variety of devastating genetic diseases before birth.

genetics↗

Structural basis of human PRPS2 filaments

PRPP synthase (PRPS) transfers the pyrophosphate groups from ATP to ribose-5-phosphate to produce 5-phosphate ribose-1-pyrophosphate (PRPP), a key intermediate in the biosynthesis of several metabolites including nucleotides, dinucleotides and some amino acids. There are three PRPS isoforms encoded in human genome. While hPRPS1 and hPRPS2 are expressed in most tissues, hPRPS3 is exclusively expressed in testis. Although hPRPS1 and hPRPS2 share 95% sequence identity, hPRPS2 has been shown to be less sensitive to allosteric inhibition and specifically upregulated in certain cancers in the translational level. Recent studies demonstrate that PRPS can form a subcellular compartment termed the cytoophidium in multiple organisms across prokaryotes and eukaryotes. Forming the cytoophidium is considered as a distinctive mechanism involving the polymerization of the protein. In order to investigate the function and molecular mechanism of hPRPS2 polymerization, we solve the polymer structure of hPRPS2 at 3.08[A] resolution using cryo-Electron Microscopy (cryo-EM). hPRPS2 hexamers stack into polymers in the conditions with the allosteric/competitive inhibitor ADP. The binding modes of ADP at the canonical allosteric site and at the catalytic active site are clearly determined. A point mutation disrupting the inter-hexamer interaction prevents hPRPS2 polymerization and results in significantly reduced catalytic activity. Our findings suggest that the regulation of hPRPS2 polymer is distinct from E. coli PRPS polymer and provide new insights to the regulation of hPRPS2 with structural basis.

biochemistry↗