Biology subjects

Xia, D.

Publications and source records attributed to Xia, D..

At least 19 recordsLinked to original sources

bioRxiv2026

Integrated anthocyanin profiling and transcriptome analysis identify candidate genes associated with petal color variation in Cyclamen persicum

Petal coloration is a key ornamental trait in Cyclamen persicum Mill. and is closely associated with anthocyanin composition and relative accumulation, yet the major anthocyanins and candidate molecular factors associated with color variation remain unclear. In this study, anthocyanin profiling and transcriptome analysis were integrated to investigate three Cyclamen materials with distinct petal colors, BXK, FXK, and SHXK. Anthocyanin profiling showed clear separation among the three materials, indicating that petal color divergence was associated with differences in anthocyanin composition and relative abundance. Petunidin-, peonidin-, delphinidin-, malvidin-, and cyanidin-related derivatives exhibited distinct accumulation patterns. Transcriptome analysis revealed marked transcriptional divergence, with phenylpropanoid and flavonoid biosynthesis repeatedly enriched across comparisons, whereas isoflavonoid and flavone and flavonol biosynthesis were enriched in selected comparisons. Mapping differentially expressed genes onto the anthocyanin biosynthetic pathway revealed branch-specific expression patterns of structural genes, including CHS, F3H/F3'H, F3'5'H, DFR, and ANS. Notably, Cluster-26256.0, annotated as a putative anthocyanidin synthase gene, showed a progressive increase in expression from BXK to FXK and SHXK, consistent with increasing petal pigmentation. Several DFR-related transcripts also showed relatively high expression in SHXK. Co-expression analysis linked key anthocyanins, structural genes, and transcription factors, while qRT-PCR generally confirmed RNA-seq trends. These results suggest that late anthocyanin biosynthesis, particularly ANS-related transcriptional variation, may contribute to dark red petal coloration. This study provides a metabolite-transcript framework for Cyclamen petal coloration and identifies ANS-related genes as priority candidates for future functional studies and flower-color breeding.

plant biology↗

bioRxiv2026

Single-atom inhibition of oncogenic drivers through cysteine coordination

Small-molecule inhibitors rely on molecular recognition within suitable binding pockets, leaving many disease-associated proteins difficult to target. Here, we introduce the concept of a single-atom inhibitor in which gold (Au) engages critical cysteine residues of oncogenic drivers to suppress their activity. We used an AI-assisted few-shot learning approach to identify EGFR-targeting peptides for in vivo Au delivery and showed that the lead candidate, 10714, promoted Au accumulation in EGFR-expressing cells and tumors. In vivo, Au exploited its intrinsic affinity for cysteine to inhibit two structurally distinct oncogenic proteins, engaging Cys797 in EGFR T790M and the mutation-derived Cys12 in KRAS G12C adjacent to their respective nucleotide-binding pockets. Structural and computational analyses supported stabilization of inactive nucleotide-bound states, while mutation of these cysteine residues abrogated Au-mediated inhibition. 10714-Au consequently suppressed oncogenic signaling, reduced non-small-cell lung cancer cell viability, and inhibited tumor growth in EGFR- and KRAS-mutant xenograft models and patient-derived organoids. These findings establish proof of principle for single-atom inhibition across structurally distinct oncogenic drivers and suggest that localized atomic coordination could provide an alternative mode of target engagement to conventional pocket-dependent inhibition.

molecular biology↗

bioRxiv2026

Port of Protein-Protein Interactomes: An experiment-based protein-protein interactome database for rice

Protein-protein interactions (PPIs) play a crucial role in enabling proteins to carry out their functions within various biological processes (Hui et al., 2003). Since the introduction of the yeast two-hybrid (Y2H) method for PPI detection in 1989 (Fields and Song, 1989), the identification of PPIs has become a significant focus in modern biological research. PPI goes beyond examining individual proteins, allowing researchers to establish a comprehensive network that regulates biological processes. Rice, as a key model organism in plant biological studies, has been at the forefront of PPI research. In 2008, prominent rice scientists in China called for concerted efforts to define a comprehensive protein-protein interaction network experimentally, which aimed to facilitate the prediction of the functional mechanisms operating throughout a plants lifecycle (Zhang et al., 2008). With efforts for 2 decades, the experimentally identified rice PPIs have reached over ten thousand. Several public databases have been established to systematically collate and store PPIs, including STRING (Szklarczyk et al., 2019), BioGRID (Oughtred et al., 2020), IntAct (del Toro et al., 2022), PRIN (Gu et al., 2011), RicePPINet (Liu et al., 2017) and RiceNet v2 (Lee et al., 2015). However, most PPI datasets in rice stem from computational predictions, while experiment-based rice PPI datasets are fragmented due to the lack of systematic profiling at the rice PPIome level, which largely hinders information sharing in the rice research community. To bridge this gap, we constructed the Port of Protein-Protein Interactomes (POPPIN; https://riceome.hzau.edu.cn/poppin/), an integrated database dedicated to sharing experimentally verified PPIs and functional clues in rice. Empowered by high-throughput PPIome profiling technologies and text mining assisted by a large language model (Huang et al., 2025; Liu et al., 2025), POPPIN currently has deposited over 150,451 pieces of rice PPI-related information. Additionally, POPPIN provides detailed protein information, including GO annotations, subcellular localizations, domains, trait ontology (TO) information, and hyperlinks to external biological databases. Through offering a user-friendly web interface for search and dynamic network visualization, POPPIN serves as the first large-scale, experiment-based database for searchable PPIs in rice, and has the potential to be extended to other species under this structural framework.

systems biology↗

bioRxiv2025

Decoding hidden goal-directed navigational states and their neuronal representations using a novel labyrinth paradigm and probabilistic modeling framework

Goal-directed navigation involves a sequence of planned actions aimed at achieving long-term goals through reinforcement, but detecting hidden states that support this process and their neuronal substrates remains a fundamental challenge. To address this, we developed a complex labyrinth test that mimics naturalistic foraging and implemented a novel hierarchical probabilistic modeling framework, Cognitive Mapping of Planned Actions with State Spaces (CoMPASS). This framework infers a nested state structure, comprising short-term surveillance-ambulation states (Level 1) and long-term goal-oriented navigational states (Level 2). Using CoMPASS, we show that successful navigation in wild-type mice is marked by increased recruitment of both surveillance and goal-oriented states specifically at decision nodes, revealing how sequential behavioral decisions culminate in long-term goals. In contrast, the humanized AppSAA mouse model of Alzheimers disease (AD) exhibited navigational impairments marked by diminished surveillance during decisions, reduced goal-directed states, and increased navigation stochasticity. Importantly, we show that gamma oscillations in the posterior parietal cortex (PPC), a region involved in spatial navigation planning, encode these CoMPASS behavioral states and their dynamic operating modes linking spatial locations to long-term goals. Our findings provide a novel paradigm for assessing hidden goal-directed navigational states and identify gamma oscillations in the PPC as their neural substrates.

neuroscience↗

bioRxiv2025

Functional Implications of the Conformational Landscape of a Multidrug Transporter Revealed by Structures of Zebrafish Abcb4

The hallmark of multidrug resistance conferred by human ABC transporter ABCB1 (hP-gp) is the recognition and efflux of diverse range of drugs, though the precise mechanism of polyspecificity remains unresolved. In aquatic animals such as zebrafish, Abcb4, a functional homolog to hP-gp, plays a vital role in surviving environmental toxicants. Here, we show that Abcb4 exhibits comparable basal and drug-stimulated ATPase activity to hP-gp. Using cryo-EM, we captured five inward-facing Abcb4 conformations with varying separations between its two lobes, illustrating its open-and- close motion. The range of separation exceeds that seen in published P-gp structures that appear to be conformationally restricted. This global open-and-close motion is coupled with individual helix movement, resulting in a highly fluid substrate-binding pocket. These dynamic changes, likely underlying the polyspecificity of substrate recognition, predict unconventional protein-ligand interactions that are supported by structures of Abcb4 bound to the P-gp inhibitors tariquidar and elacridar, and the substrate vincristine.

biochemistry↗

bioRxiv2025

Anti-Aβ immunotherapy-mediated amyloid clearance attenuates microglial activation without inducing exhaustion at residual plaques

Anti-amyloid {beta}-peptide (A{beta}) immunotherapy was developed to reduce amyloid plaque pathology and slow cognitive decline during progression of Alzheimers disease. Efficient amyloid plaque clearance has been proven in clinical trials testing anti-A{beta} antibodies, with the impact on cognitive endpoints correlating with the extent of plaque removal. However, treatment is associated with adverse side-effects, such as oedema and haemorrhages, which are potentially linked to the induced immune response. To improve the safety profile of these molecules, it is imperative to understand the consequences of anti-A{beta} antibody treatment on immune cell function. Here, we investigated the effects of long-term chronic anti-A{beta} treatment on amyloid plaque pathology and microglial response in the APP-SAA triple knock-in mouse model. Mice were treated weekly with anti-A{beta} antibody from 4-8 months of age. Long-term treatment with anti-A{beta} results in a robust and dose-dependent removal of amyloid plaque pathology, with a higher efficiency for removing diffuse over dense-core plaques. Analysis of the CSF proteome indicates a reduction of markers for neurodegeneration including Tau and -Synuclein, as well as immune cell related proteins. Bulk RNA-seq revealed a dose-dependent decrease in brain-wide disease-associated microglial (DAM) and glycolytic gene expression, which is supported by a parallel decrease of glucose uptake and protein levels of Triggering receptor of myeloid cells 2 (Trem2) protein, a major immune receptor involved in DAM activation of microglia. In contrast, DAM activation around remaining plaques remains high regardless of treatment dose. In addition, microglia surrounding remaining plaques display a dose-dependent increase in microglial clustering and a selective increase in antigen presenting and immune signalling proteins. These findings demonstrate that long-term chronic anti-A{beta} mediated removal of A{beta} leads to a dose dependent decrease in brain-wide microglial DAM activation and neurodegeneration, while microglia at residual plaques display a combined DAM and antigen presenting phenotype that suggests a continued treatment response. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=161 SRC="FIGDIR/small/645950v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@6d1a49org.highwire.dtl.DTLVardef@d8c14dorg.highwire.dtl.DTLVardef@7ae330org.highwire.dtl.DTLVardef@1d96cc3_HPS_FORMAT_FIGEXP M_FIG Graphical abstract: Schematic overview of the effects of chronic long-term anti-A treatment in APP-SAA mice Schematic was created with BioRender.com C_FIG

neuroscience↗

bioRxiv2024

Optimizing Genome Editing in Bovine Cells: A Comparative Study of Cas9 Variants and CRISPR Delivery Methods

To assist in the establishment of an efficient CRISPR/Cas9 gene editing workflow in bovine cells, we compared the efficiency of four Streptococcus pyogenes Cas9 (SpCas9) nuclease variants (produced in-house or commercially) and two different Cas9/sgRNA ribonucleoprotein (RNP) delivery methods applied to Madin-Darby bovine kidney (MDBK) cells (Bos taurus). We targeted three genes for simple sequence deletion or modification via a single-stranded oligodeoxynucleotide donor template: the testis-determining gene Sry (sex-determining region on Y chromosome), germ cell-specific gene Nanos2 (nanos C2HC-type zinc finger 2) and PRLR (prolactin receptor). RNPs and donor templates were delivered into cells via lipofectamine CRISPRMAX transfection or Neon electroporation. The efficiency of gene editing was determined by target-specific PCR genotyping, real-time PCR assays and next generation sequencing analyses. When targeting Sry, the commercial Alt-R High-Fidelity (HiFi) SpCas9 nuclease exhibited the highest deletion efficiency, followed by the in-house generated Sniper2L, HiFi SpCas9 and wild-type SpCas9. Notably, for PRLR and Nanos2, Sniper2L induced comparable editing outcomes to Alt-R HiFi SpCas9. The two delivery methods, lipofectamine CRISPRMAX transfection and Neon electroporation, demonstrated similar efficiency (60% to 83%) in producing indels in all three target genes. However, Neon electroporation (5.5% to 11%) was superior to CRISPRMAX lipofection (1.5% to 4.8%) at inducing target-specific sequence knock-ins. Strategies to inhibit NHEJ repair and/or enhance HDR may be necessary to improve HDR efficiency in these bovine cells. These findings provide valuable insights for improving gene editing outcomes in bovines and may assist in accelerating the widespread application of genome editing technology in large animals.

molecular biology↗

bioRxiv2024

Impact of commercial gut health interventions on caecal metagenome and broiler performance

BackgroundMaintaining gut health is a persistent and unresolved challenge in the poultry industry. Given the critical role of gut health in chicken performance and welfare, there is a pressing need to identify effective gut health intervention (GHI) strategies to ensure optimal outcomes in poultry farming. In this study, across three broiler production cycles, we compared the metagenomes and performance of broilers provided with ionophores as control against birds subjected to five different GHI combinations involving vaccination, probiotics, prebiotics, essential oils, and reduction of ionophore use. ResultsUsing a binning strategy, 84 ([≥]75% completeness, [≤] 5% contamination) metagenome-assembled genomes (MAGs) from 118 caecal samples were recovered and annotated for their metabolic potential. The majority of these (n = 52, 61%) had a differential response across all cohorts and are associated with the performance parameter - European Poultry Efficiency Factor (EPEF). The control group exhibited the highest EPEF, followed closely by the cohort where probiotics are used in conjunction with vaccination. The use of Probiotics B, a commercial Bacillus strain-based formulation, was determined to contribute to the superior performance of birds. GHI supplementation generally affected abundance of microbial enzymes relating to carbohydrate and protein digestion, and metabolic pathways relating to energy, nucleotide synthesis, short-chain fatty acid synthesis, and drug-transport systems. These shifts are hypothesised to differentiate performance among groups and cycles, highlighting the beneficial role of several bacteria including Rikenella microfusus and UBA7160 species. ConclusionsAll GHIs are shown to be effective methods for gut microbial modulation, with varying influences on MAG diversity, composition and microbial functions. These metagenomic insights greatly enhance our understanding of microbiota-related metabolic pathways, enabling us to devise strategies against enteric pathogens related to poultry products and presenting new opportunities to improve overall poultry performance and health.

microbiology↗

bioRxiv2024

The intestinal microbiome and Cetobacterium somerae inhibit viral infection through TLR2-type I IFN signaling axis in zebrafish

Accumulated evidences demonstrate that intestinal microbiome can inhibit viral infection. However, our knowledge of the signaling pathways and specific commensal microbes that mediate the antiviral response is limited. Here, a rhabdoviral infection model in zebrafish allows us to investigate the modes of action of microbiome-mediated antiviral effect. We observed that antibiotics-treated and germ-free zebrafish exhibited greater viral infection. Mechanistically, depletion of the intestinal microbiome alters TLR2-Myd88 signaling, and blunts neutrophil response and type I interferon (IFN) production. Moreover, a single commensal bacterium, Cetobacterium somerae, recapitulated TLR2- and type I IFN-dependent antiviral effect of the microbiome in gnotobiotic zebrafish, and C. somerae exopolysaccharides (CsEPS) was the effector molecule that engaged TLR2 to mediate antiviral function. Together, our results suggest a conserved role of intestinal microbiome in regulating type I IFN response among vertebrates, and reveal that the intestinal microbiome inhibits viral infection through a CsEPS-TLR2-type I IFN signaling axis in zebrafish.

microbiology↗

bioRxiv2024

Multi-omics analysis reveals regime shifts in the gastrointestinal ecosystem in chickens following anticoccidial vaccination and Eimeria tenella challenge

Coccidiosis, caused by Eimeria parasites, poses significant economic and welfare challenges in poultry farming. Beyond its direct impact on health, Eimeria infection disrupts enteric microbial populations leading to dysbiosis and increases vulnerability to secondary diseases such as necrotic enteritis, caused by Clostridium perfringens. The impact of Eimeria infection or anticoccidial vaccination on host gastrointestinal phenotypes and enteric microbiota remains understudied. In this study, the metabolomic profiles and microbiota composition of chicken caecal tissue and contents were evaluated concurrently during a controlled experimental vaccination and challenge trial. Cobb500 broilers were vaccinated with a Saccharomyces cerevisiae-vectored anticoccidial vaccine and challenged with 15,000 Eimeria tenella oocysts. Assessment of caecal pathology and quantification of parasite load revealed correlations with alterations to caecal microbiota and host metabolome linked to infection and vaccination status. Infection heightened microbiota richness with increases in potentially pathogenic species, while vaccination elevated beneficial Bifidobacterium. Using a multi-omics factor analysis (MOFA) machine learning model, data on caecal microbiota and host metabolome were integrated and distinct profiles for healthy, infected, and recovering chickens were identified. Healthy and recovering chickens exhibited higher vitamin B metabolism linked to short-chain fatty acid-producing bacteria, whereas essential amino acid and cell membrane lipid metabolisms were prominent in infected and vaccinated chickens. Notably, vaccinated chickens showed distinct metabolites related to the enrichment of sphingolipids, important components of nerve cells and cell membranes. Our integrated multi-omics model revealed latent biomarkers indicative of vaccination and infection status, offering potential tools for diagnosing infection, monitoring vaccination efficacy, and guiding the development of novel treatments or controls.

microbiology↗

bioRxiv2024

Mitochondria drive microglial NRLP3 inflammasome activation via TSPO

Uncontrolled microglial response is core to neuroinflammatory brain diseases. The correlation between the mitochondrial protein TSPO and inflammation has so far failed to explain whether TSPO positively or negatively regulates microglial function. The recent evidence on the species specificity of TSPO in microglia demands a deeper understanding of the protein biology in these brain-resident macrophages. To this end, we have here enrolled a murine model of microglial cells showing that TSPO is required for the priming of mitochondria to inflammation and a conduit for its escalation. Namely, in response to inflammatory cues TSPO is stabilised on the mitochondria where it binds and sequesters NOD-like receptor (NLR) protein (i), represses the PARK2-mediated mitophagy (ii) and engages the retrograde communication with the nucleus via the accumulation of the Nf-kB to promote the expression of pro-inflammatory genes (iii). Notably, the TSPO sustained inflammatory response drives cellular demise and ultimately leads to excitotoxicity (iv). Our findings advance the current knowledge of TSPO widening the understanding of mitochondria in inflammation and indicating a target for their regulation.

cell biology↗

bioRxiv2024

Gating of Memory to Behavior by the Locus Coeruleus

An essential function of memory is to guide behavior for survival and adaptation. While considerable knowledge has been accumulated on memory formation, much less is understood about how retrieved memories direct behavior/action. In the auditory Pavolovian threat conditioning paradigm, retrieval of conditioned threat memory activates dorsomedial prefrontal (dmPFC) neurons exhibiting transient responses (T-neurons), which activate both dmPFC neurons exhibiting sustained responses (S-neurons) and locus coeruleus (LC) neurons. Auditory inputs to S-neurons enable the conversion from transient to sustained responses so that the freezing durations match those of the auditory cues. Activation of LC neurons is required for the conversion by enhancing S-neuron responses, which, interestingly, opens a short time window during which non-conditioned cues also lead to freezing. The transition from memory to behavior thus hinges on the integration of retrieved memory, sensory inputs, and emotional/body state cues to generate a selective, adequate, and finely tuned behavior. Significance statementThis study provides new insights into the neural circuitry and mechanisms of how retrieved memories direct the execution of behavior in response to conditioned threatening stimuli. It reveals how different neuron types in the dmPFC interact with LC neurons to determine and modulate the duration and intensity of defensive responses. It also shows that activation of LC neurons can induce the generalization of freezing to non-threatening cues, which may have implications for understanding anxiety disorders. This study contributes to the field of neuroscience by advancing the understanding of memory-behavior conversion and role of the dmPFC and LC in conditioned threat/fear behavior.

neuroscience↗

bioRxiv2023

Identification of methylation markers for age and Bovine Respiratory Disease in dairy cattle

Methylation profiles of animals is known to differ by age and disease status. Bovine respiratory disease (BRD), a complex infectious disease, primarily affects calves and has significant impact on animal welfare and the cattle industry, predominantly from production losses. BRD susceptibility is multifactorial, influenced by both environmental and genetic factors. We investigated the epigenetic profile of BRD susceptibility in calves and age-related methylation differences between healthy calves and adult dairy cows using Reduced Representation Bisulfite Sequencing (RRBS). We identified 3,452 genes within differentially methylated regions between calves and adults. Functional analysis revealed enrichment of developmental pathways including cell fate commitment and tissue morphogenesis. Between healthy and BRD affected calves, 964 genes were identified within differentially methylated regions. Immune and vasculature regulatory pathways were enriched and key candidates in BRD susceptibility involved in complement cascade regulation, vasoconstriction and respiratory cilia structure and function were identified.

genetics↗

bioRxiv2023

Point mutations in Arf1 reveal cooperative effects of the N-terminal region and myristate for GTPase-activating protein catalytic activity

The ADP-ribosylation factors (Arfs) constitute a family of small GTPases within the Ras superfamily, with a distinguishing structural feature of a hypervariable N-terminal extension of the G domain modified with myristate. Arf proteins, including Arf1, have roles in membrane trafficking and cytoskeletal dynamics. While screening for Arf1:small molecule co-crystals, we serendipitously solved the crystal structure of the non-myristoylated engineered mutation [L8K]Arf1 in complex with a GDP analogue. Like wild-type (WT) non-myristoylated Arf1*GDP, we observed that [L8K]Arf1 exhibited an N-terminal helix that occludes the hydrophobic cavity that is occupied by the myristoyl group in the GDP-bound state of the native protein. However, the helices were offset from one another due to the L8K mutation, with a significant change in position of the hinge region connecting the N-terminus to the G domain. Hypothesizing that the observed effects on behavior of the N-terminus affects interaction with regulatory proteins, we mutated two hydrophobic residues to examine the role of the N-terminal extension for interaction with guanine nucleotide exchange factors (GEFs) and GTPase Activating Proteins (GAPs). Different than previous studies, all mutations were examined in the context of myristoylated Arf. Mutations had little or no effect on spontaneous or GEF-catalyzed guanine nucleotide exchange but did affect interaction with GAPs. [F13A]myrArf1 was less than 1/2500, 1/1500, and 1/200 efficient as substrate for the GAPs ASAP1, ARAP1 and AGAP1; however, [L8A/F13A]myrArf1 was similar to WT myrArf1. We hypothesized that the myristate moiety associates with the N-terminal extension to alter its structure, thereby affecting its function. Using molecular dynamics simulations, the effect of the mutations on forming alpha helices was examined, yet no differences were detected. The results indicate that lipid modifications of GTPases and consequent anchoring to a membrane influences protein function beyond simple membrane localization. Hypothetical mechanisms are discussed.

biochemistry↗

bioRxiv2023

Prominent contributions of selective neuronal subtypes to pediatric drug-resistant focal dysplasia

About 75% cases of epilepsy begin during childhood, and 10 - 30% of pediatric epilepsy patients are resistant to drug treatment. The predominant seizure type in children is focal cortical dysplasia (FCD) which is highly associated with drug-resistant epilepsy, but its underlying cause is poorly understood. We performed single-cell RNA sequencing and patch-clamp recording on fresh brain tissues obtained from pediatric FCD patients shortly after surgery to reveal critical factors contributing to FCD. We report that known epilepsy genes or significant transcriptomic alterations occur in only a few neuronal subgroups, suggesting that epilepsy-associated neurons cluster into only a few neuronal subtypes. These epilepsy-subtypes displayed significant epilepsy-related transcriptomic alterations, especially in the genes associated with excitation/inhibition balance and neuron functional signal pathways. Among eight epilepsy-subtypes, L2_4_CUX2_YWHAH and PVALB_RGS5 subtypes showed the most prominent alterations in FCD patient tissues. Supporting PV-neurons being important, recording from fast-spiking/parvalbumin-containing neurons in acute FCD patient brain slices revealed reduced excitatory synaptic inputs, implicating lower activity in these neurons and fewer synaptic inputs onto them. A higher percentage of mitochondria genes, and likely higher activity in the pathways associated with oxidative phosphorylation and ATP biosynthetic process, was observed in the epilepsy-subtypes, suggesting a high energy expenditure in them. Interestingly, the activity of the above two pathways in most epilepsy-subtypes was lower in the FCD patients, suggesting these subtypes may be more vulnerable to energy deficit in epilepsy. Altogether, transcriptomics is significantly altered in only a few neuronal subtypes in pediatric FCD patient brains. These selective epilepsy-subtypes may play prominent roles in the genesis of pediatric drug-resistant seizure and targeting them may provide new treatment options.

bioinformatics↗

bioRxiv2022

An integrated cell barcoding and computational analysis pipeline for scalable analysis of differentiation at single-cell resolution

Pluripotent stem cells provide a scalable approach to analyse molecular regulation of cell differentiation across multiple developmental lineage trajectories. In this study, we engineered barcoded iPSCs to generate an atlas of multilineage differentiation from pluripotency, encompassing a time-course of WNT-induced differentiation perturbed using modulators of WNT, BMP, and VEGF signalling. Computational mapping of in vitro cell types to in vivo developmental lineages revealed a diversity of iPSC-derived cell types comprising mesendoderm lineage cell types including lateral plate and paraxial mesoderm, neural crest, and primitive gut. Coupling this atlas of in vitro differentiation with Summary data-based Mendelian Randomisation analysis of human complex traits, we identify the WNT-inhibitor protein TMEM88 as a putative regulator of mesendodermal cell types governing development of diverse cardiovascular and anthropometric traits. Using genetic loss of function models, we show that TMEM88 is required for differentiation of diverse endoderm and mesoderm cell lineages in vitro and that TMEM88 knockout in vivo results in a significant dysregulation of arterial blood pressure. This study provides an atlas of multilineage iPSC differentiation coupled with new molecular, computational, and statistical genetic tools to dissect genetic determinants of mammalian developmental physiology.

genomics↗

bioRxiv2022

Molecular basis for antiviral activity of pediatric neutralizing antibodies targeting SARS-CoV-2 Spike receptor binding domain

Neutralizing antibodies (NAbs) hold great promise for clinical interventions against SARS-CoV- 2 variants of concern (VOCs). Understanding NAb epitope-dependent antiviral mechanisms is crucial for developing vaccines and therapeutics against VOCs. Here we characterized two potent NAbs, EH3 and EH8, isolated from an unvaccinated pediatric patient with exceptional plasma neutralization activity. EH3 and EH8 cross-neutralize the early VOCs and mediate strong Fc-dependent effector activity in vitro. Structural analyses of EH3 and EH8 in complex with the receptor-binding domain (RBD) revealed the molecular determinants of the epitope-driven protection and VOC-evasion. While EH3 represents the prevalent IGHV3-53 NAb whose epitope substantially overlaps with the ACE2 binding site, EH8 recognizes a narrow epitope exposed in both RBD-up and RBD-down conformations. When tested in vivo, a single-dose prophylactic administration of EH3 fully protected stringent K18-hACE2 mice from lethal challenge with Delta VOC. Our study demonstrates that protective NAbs responses converge in pediatric and adult SARS-CoV-2 patients.

microbiology↗

bioRxiv2022

Deep learning accurately quantifies plasma cell percentages on CD138-stained bone marrow samples

BackgroundThe diagnosis of plasma cell neoplasms requires accurate, and ideally precise, percentages. This plasma cell percentage is often determined by visual estimation of CD138-stained bone marrow biopsies and clot sections. While not necessarily inaccurate, estimates are by definition imprecise. For this study, we hypothesized that deep learning can be used to improve precision. MethodsWe trained a semantic segmentation-based convolutional neural network (CNN) using annotations of CD138+ and CD138- cells provided by one pathologist on small image patches of bone marrow and validated the CNN on an independent test set of images patches using annotations from two pathologists and a non-deep-learning commercial software. Once satisfied with performance, we scaled-up the CNN to evaluate whole slide images (WSIs), and deployed the system as a workflow friendly web application to measure plasma cell percentages using snapshots taken from microscope cameras. ResultsOn validation image patches, we found that the intraclass correlation coefficients for plasma cell percentages between the CNN and pathologist #1, a non-deep learning commercial software and pathologist #1, and pathologists #1 and #2 were 0.975, 0.892, and 0.994, respectively. The overall results show that CNN labels were almost as accurate pathologist labels at a cell-by-cell level. On WSIs from 10 clinical cases, the CNN continued to perform well, and identified two cases where the sign-out pathologist overestimated plasma cell percentages. ConclusionsThe high labeling accuracy of the CNN supports its eventually application as a computational second-opinion tool for the measurement of plasma cell percentages in clinical practice.

pathology↗