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Yuan, F.

Publications and source records attributed to Yuan, F..

At least 37 records · Page 2Linked to original sources

Membrane Expression Enhances Folding, Multimeric Structure Formation, and Immunogenicity of Viral Capsid Proteins

Viral capsid proteins are widely explored for subunit vaccine development but are often hampered by their complexity of production and low immunogenicity. Here, we report a simple approach to overcome these challenges by combining mRNA vaccine technology with protein engineering. Using African swine fever virus (ASFV) capsid proteins P72 and penton as models, we engineered them into membrane-bound and secreted forms, and compared their immunogenicity to the native intracellular form in mice and pigs through mRNA vaccination. The membrane-bound and secreted P72 and penton folded into their native multimeric structure independent of viral chaperone, therefore preserving their conformational epitopes. The membrane-bound P72 and penton also elicited significantly stronger antibody and T cell responses than their secreted or intracellular counterparts. Our study provides a simple approach to enhance folding, multimeric structure formation, and immunogenicity of viral capsid proteins for ASFV subunit vaccine development and immunogenicity of intracellular proteins in general.

immunology↗

Mapping snoRNA-target RNA interactions in an RNA binding protein-dependent manner with chimeric eCLIP

Small nucleolar RNAs (snoRNAs) are non-coding RNAs that function in ribosome and spliceosome biogenesis, primarily by guiding modifying enzymes to specific sites on ribosomal RNA (rRNA) and spliceosomal RNA (snRNA). However, many orphan snoRNAs remain uncharacterized, with unidentified or unvalidated targets, and studies on additional snoRNA-associated proteins are limited. We adapted an enhanced chimeric eCLIP approach to comprehensively profile snoRNA-target RNA interactions using both core and accessory snoRNA binding proteins as baits. Using core snoRNA binding proteins, we confirmed most annotated snoRNA-rRNA and snoRNA-snRNA interactions in mouse and human cell lines and called novel, high-confidence interactions for orphan snoRNAs. While some of these interactions result in chemical modification, others may have modification-independent functions. We then showed that snoRNA ribonucleoprotein complexes containing certain accessory proteins, like WDR43 and NOLC1, enriched for specific subsets of snoRNA-target RNA interactions with distinct roles in ribosome and spliceosome biogenesis. Notably, we discovered that SNORD89 guides 2-O-methylation at two neighboring sites in U2 snRNA that are important for activating splicing, but also appear to ensure imperfect splicing for a subset of near-constitutive exons. Thus, chimeric eCLIP of snoRNA-associating proteins enables a comprehensive framework for studying snoRNA-target interactions in an RNA binding protein-dependent manner, revealing novel interactions and regulatory roles in RNA biogenesis.

genomics↗

Toward De Novo Protein Design from Natural Language

Programming biological function-designing bespoke proteins to perform specified molecular tasks-is a foundational goal of molecular engineering. However, current design paradigms remain fundamentally limited: they typically require either natural proteins as starting points for optimization or manual reformulation of functional goals as geometric and sequence-level constraints to guide candidate generation. Here we introduce Pinal, a 16-billion-parameter foundation model that designs candidate proteins from natural-language descriptions of desired function. Trained on 1.7 billion synthetically annotated protein-text pairs, Pinal links functional intent to protein sequence and structure. In computational evaluations, generated candidates combined high predicted foldability with functional-description alignment and sequence diversity, providing a basis for prioritizing experimentally testable designs. We applied Pinal to four distinct design tasks-a fluorescent protein, a polyethylene terephthalate hydrolase, an alcohol dehydrogenase and a metabolic H-protein-and experimentally observed the intended function in each case, including catalytic activity for both designed enzymes. Crucially, without iterative experimental optimization, a Pinal-designed H-protein increased product titer by 1.7-fold relative to the corresponding native E. coli H-protein in a multi-enzyme CO2 fixation pathway. These findings support natural language as a high-level interface for candidate generation in protein design, enabling programmable exploration with reduced reliance on manually specified structural or sequence constraints.

bioengineering↗

Digital Immunoassay for Rapid Detection of SARS-CoV-2 Infection in a Broad Spectrum of Animals

The ability of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) to infect a wide-range of species raises significant concerns regarding both human-to-animal and animal-to-human transmission. There is an increasing demand for highly sensitive, rapid, and simple diagnostic assays that can detect viral infection across various species. In this study, we developed a biosensor assay that adapted a monoclonal-antibody (mAb)-based blocking ELISA format into an Activate Capture + Digital Counting (AC + DC)-based immunoassay. The assay employs a photonic crystal (PC) biosensor, gold-nanoparticle (AuNP) tags, SARS-CoV-2 nucleocapsid (N) protein, and specific anti-N mAb to detect antibody responses in animals exposed with SARS-CoV-2. We demonstrated a simple 2-step 15-min test that was capable of detecting as low as 12.5 ng of antibody in controlled standard serum samples. Based on an evaluation of 176 cat serum samples with known antibody status, an optimal percentage of inhibition (PI) cut-off value of 0.588 resulted in a diagnostic sensitivity of 98.3% and a diagnostic specificity of 96.5%. The test is highly repeatable with low variation coefficients of 2.04%, 2.73%, and 4.87% across different runs, within a single run, and on a single chip, respectively. The test was further employed to detect antibody responses in multiple animal species as well as investigate dynamics of antibody response in experimentally infected cats. This test platform provides an important tool for rapid field surveillance of SARS-CoV-2 infection across multiple species.

microbiology↗

ProTrek: Navigating the Protein Universe through Tri-Modal Contrastive Learning

ProTrek redefines protein exploration by seamlessly fusing sequence, structure, and natural language function (SSF) into an advanced tri-modal language model. Through contrastive learning, ProTrek bridges the gap between protein data and human understanding, enabling lightning-fast searches across nine SSF pairwise modality combinations. Trained on vastly larger datasets, ProTrek demonstrates quantum leaps in performance: (1) Elevating protein sequence-function interconversion by 30-60 fold; (2) Surpassing current alignment tools (i.e., Foldseek and MMseqs2) in both speed (100-fold acceleration) and accuracy, identifying functionally similar proteins with diverse structures; and (3) Outperforming ESM-2 in 9 of 11 downstream prediction tasks, setting new benchmarks in protein intelligence. These results suggest that ProTrek will become a core tool for protein searching, understanding, and analysis.

bioinformatics↗

SaprotHub: Making Protein Modeling Accessible to All Biologists

Training and deploying large-scale protein language models typically requires deep machine learning expertise -- a barrier for researchers outside this field. SaprotHub overcomes this challenge by offering an intuitive platform that facilitates training and prediction as well as storage and sharing of models. We provide the ColabSaprot framework built on Google Colab which potentially powers hundreds of protein training and prediction applications, enabling researchers to collaboratively build and share customized models.

bioinformatics↗

Therapeutic Activity of Resolvin D1 (RvD1) in Murine MASH

Background and AimsRecent studies have highlighted the beneficial effect of resolvin D1 (RvD1), a DHA-derived specialized pro-resolving mediator, on metabolic dysfunction-associated steatohepatitis (MASH), but the underlying mechanisms are not well understood. Our study aims to determine the mechanism by which RvD1 protects against MASH progression. MethodsRvD1 was administered to mice with experimental MASH, followed by bulk and single-cell RNA sequencing analysis. Primary cells including bone marrow-derived macrophages (BMDMs), Kupffer cells, T cells, and primary hepatocytes were isolated to elucidate the effect of RvD1 on inflammation, cell death, and fibrosis regression genes. ResultsHepatic tissue levels of RvD1 were decreased in murine and human MASH, likely due to an expansion of pro-inflammatory M1-like macrophages with diminished ability to produce RvD1. Administering RvD1 reduced inflammation, cell death, and liver fibrosis. Mechanistically, RvD1 reduced inflammation by suppressing the Stat1-Cxcl10 signaling pathway in macrophages and prevented hepatocyte death by alleviating ER stress-mediated apoptosis. Moreover, RvD1 induced Mmp2 and decreased Acta2 expression in hepatic stellate cells (HSCs), and promoted Mmp9 and Mmp12 expression in macrophages, leading to fibrosis regression in MASH. ConclusionsRvD1 reduces Stat1-mediated inflammation, mitigates ER stress-induced apoptosis, and promotes MMP-mediated fibrosis regression in MASH. This study highlights the therapeutic potential of RvD1 to treat MASH. Impact and implicationsMetabolic dysfunction-associated steatohepatitis (MASH) is an increasing healthcare burden worldwide. Current treatments for MASH and its sequelae are very limited. Recent studies highlighted the therapeutic benefit of specialized pro-resolving mediators (SPMs), including resolvin D1 (RvD1), in liver diseases. However, the mechanisms underlying these beneficial effects are not well understood. Based on unbiased transcriptomic analyses using bulk and single-cell RNA sequencing in RvD1-treated MASH livers, we show that RvD1 suppresses Stat1-mediated inflammatory responses and ER stress-induced apoptosis, and induces gene expression related to fibrosis regression. Our study provides new mechanistic insight into the role of RvD1 in MASH and highlights its therapeutic potential to treat MASH. HighlightsO_LILiver RvD1 levels are decreased in MASH patients and MASH mice C_LIO_LIRvD1 administration suppresses Stat1-mediated inflammatory response C_LIO_LIRvD1 administration alleviates ER stress-induced apoptosis C_LIO_LIRvD1 administration induces fibrosis regression gene expression C_LI

pharmacology and toxicology↗

The first discovery of SFTSV in the Centre of Metropolitan Beijing, China

Severe fever with thrombocytopenia virus (SFTSV), an emerging tick-borne bandavirus, poses a significant public health threat in rural China. Since 2021, an increase in local cases has been noted in the rural-urban fringe surrounding Beijing. This study aimed to assess the formation of natural foci in urban areas by conducting a field survey of ticks and hedgehogs from Beijings second to fifth ring roads. Our survey revealed a diverse tick population in city parks, including the major SFTSV vector, H. longicornis. Parthenogenetic H. longicornis, known for its role in rapid SFTSV spread, was identified in key locations like Beihai Park and Taoranting Park, near the Forbidden City. Notably, high SFTSV seroprevalence and RNA prevalence were found in hedgehogs and parasitic ticks in the center of Beijing. These findings highlight the circulation of SFTSV in central Beijing, underscoring the need for urgent attention and enhanced surveillance measures.

microbiology↗

Protein language models-assisted engineering of Uracil-N glycosylase enables programmable T-to-G and T-to-C base editing

Current base editors use DNA deamination enzymes, such as cytidine deaminase (CBE) or adenine deaminase (ABE), to facilitate transition nucleotide substitutions. Combining CBE or ABE with glycosylase enzymes, including CGBE and AYBE, can induce limited transversion mutations. Nonetheless, a critical demand remains for base editors capable of generating alternative mutation types, such as T>G corrections, which could address over 17% of monogenic SNVs responsible for human genetic diseases. In this study, we leveraged protein language models to engineer a uracil-N-glycosylase (UNG) variant with altered substrate specificities to thymines (eTDG). Notably, after only two rounds of testing fewer than 50 predicted variants, more than 50% exhibited a 1.5-11-fold enhancement in enzymatic activities, a success rate much greater than random mutagenesis. When eTDG was fused with Cas9 nickase without deaminases, it effectively induced programmable T to G or T to C substitutions and precisely corrected db/db diabetic mutation in mice (up to 55%). Our findings not only establish orthogonal strategies for developing novel base editors, but also demonstrate the capacities of protein language models for optimizing enzymes without extensive task-specific training data or laborious experimental procedures.

bioengineering↗

Mimetic butterfly wings through mimetic butterfly eyes: Evidence that brightness vision helps Adelpha fessonia identify potential mates

Color vision is thought to play a key role in the evolution of animal coloration, while achromatic vision is rarely considered as a mechanism for species recognition. Here we test the hypothesis that brightness vision rather than color vision helps Adelpha fessonia butterflies identify potential mates while their co-mimetic wing coloration is indiscriminable to avian predators. We examine the trichromatic visual system of A. fessonia and characterize its photoreceptors using RNA-seq, eyeshine, epi- microspectrophotometry and optophysiology. We model the discriminability of its wing color patches in relation to those of its co-mimic, A. basiloides, through A. fessonia and avian eyes. Visual modeling suggests that neither A. fessonia nor avian predators can readily distinguish the co-mimics coloration using chromatic or achromatic vision under natural conditions. These results suggest that mimetic colors are well-matched to visual systems to maintain mimicry, and that mate avoidance between these two look-alike species relies on other cues.

evolutionary biology↗

SaProt: Protein Language Modeling with Structure-aware Vocabulary

AO_SCPLOWBSTRACTC_SCPLOWLarge-scale protein language models (PLMs), such as the ESM family, have achieved remarkable performance in various downstream tasks related to protein structure and function by undergoing unsupervised training on residue sequences. They have become essential tools for researchers and practitioners in biology. However, a limitation of vanilla PLMs is their lack of explicit consideration for protein structure information, which suggests the potential for further improvement. Motivated by this, we introduce the concept of a "structure-aware vocabulary" that integrates residue tokens with structure tokens. The structure tokens are derived by encoding the 3D structure of proteins using Foldseek. We then propose SaProt, a large-scale general-purpose PLM trained on an extensive dataset comprising approximately 40 million protein sequences and structures. Through extensive evaluation, our SaProt model surpasses well-established and renowned baselines across 10 significant downstream tasks, demonstrating its exceptional capacity and broad applicability. We have made the code1, pre-trained model, and all relevant materials available at https://github.com/westlake-repl/SaProt.

bioinformatics↗

Generative Diffusion Models for Antibody Design, Docking, and Optimization

In recent years, optimizing antibody binding affinity for biomedical applications has become increasingly important. However, traditional wet-experiment-based approaches are time-consuming and inefficient. To address this issue, we propose a diffusion model-based antibody optimization pipeline to improve binding affinity. Our approach involves two key models: AbDesign for designing antibody sequences and structures, and AbDock, a paratope-epitope docking model, used for screening designed CDRs. On an independent test set, our AbDesign demonstrates the exceptional performance of an RMSD of 2.56[A] in structure design and an amino acid recovery of 36.47% in sequence design. In a paratope-epitope docking test set, our AbDock achieves a state-of-the-art performance of DockQ 0.44, irms 2.71[A], fnat 0.40, and Lrms 6.29[A]. The effectiveness of the optimization pipeline is further experimentally validated by optimizing a flaviviruse antibody 1G5.3, resulting in a broad-spectrum antibody that demonstrates improved binding to 6 out of the nine tested flaviviruses. This research offers a general-purpose methodology to enhance antibody functionality without training on data from specific antigens.

bioinformatics↗

Oligodendroglia generate vascular mural cells and neurons in the adult mouse brain

BACKGROUNDOligodendroglia encompass oligodendrocyte precursor cells (OPCs) and oligodendrocytes (OLs). In the grey matter of the cortex, nearly all OPCs divide slowly, yet they dont differentiate solely into mature OLs, leaving the exact role of these OPCs in the grey matter enigmatic. METHODSOligodendroglia, including OPCs, were traced using the Sox10 Cre-ERT2 reporter mice. We compared the effect of tamoxifen dissolved in different solvents on the fate of Sox10 cells. We also compared the effect of tamoxifen dosage on the fate of Sox10 cells. The differentiation of labeled red fluorescent protein (RFP) cells was analyzed using immunofluorescence staining. RESULTSTwo groups of RFP cells, type A Sox10 (Sox10-A) cells, and type B Sox10 (Sox10-B) cells, were identified in the cortex, striatum, hippocampus, thalamus, and hypothalamus. Sox10-A cells differentiate into platelet-derived growth factor receptor-{beta} (PDGFR{beta})+, CD13+ pericytes, and smooth muscle myosin heavy chain 11 (MYH11) + smooth muscle cells when the mice received ethanol or high-dose tamoxifen. Sox10-B cells transform into glutamatergic neurons when the mice received high-dose tamoxifen. Sox10-B cells include perineurona OPCs and OLs. CONCLUSIONSThis investigation provides evidence that a substantial proportion of oligodendroglia in the grey matter serve as mural cell precursors and neuronal precursors. These two phenomena may contribute to our understanding of neurodegenerative diseases. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/549127v1_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@1b7bef9org.highwire.dtl.DTLVardef@5af54borg.highwire.dtl.DTLVardef@19e3d45org.highwire.dtl.DTLVardef@1c881f1_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

Ubiquitin-driven protein condensation promotes clathrin-mediated endocytosis

Clathrin-mediated endocytosis is an essential cellular pathway that enables signaling and recycling of transmembrane proteins and lipids. During endocytosis, dozens of cytosolic proteins come together at the plasma membrane, assembling into a highly interconnected network that drives endocytic vesicle biogenesis. Recently, multiple groups have reported that early endocytic proteins form flexible condensates, which provide a platform for efficient assembly of endocytic vesicles. Given the importance of this network in the dynamics of endocytosis, how might cells regulate its stability? Many receptors and endocytic proteins are ubiquitylated, while early endocytic proteins such as Eps15 contain ubiquitin-interacting motifs. Therefore, we examined the influence of ubiquitin on the stability of the early endocytic protein network. In vitro, we found that recruitment of small amounts of polyubiquitin dramatically increased the stability of Eps15 condensates, suggesting that ubiquitylation could nucleate endocytic assemblies. In live cell imaging experiments, a version of Eps15 that lacked the ubiquitin-interacting motif failed to rescue defects in endocytic initiation created by Eps15 knockout. Furthermore, fusion of Eps15 to a deubiquitylase enzyme destabilized nascent endocytic sites within minutes. In both in vitro and live cell settings, dynamic exchange of Eps15 proteins, a hallmark of liquid-like systems, was modulated by Eps15-Ub interactions. These results collectively suggest that ubiquitylation drives assembly of the flexible protein network responsible for catalyzing endocytic events. More broadly, this work illustrates a biophysical mechanism by which ubiquitylated transmembrane proteins at the plasma membrane could regulate the efficiency of endocytic recycling. Significance StatementThe assembly of proteins into dynamic, liquid-like condensates is an emerging principle of cellular organization. During clathrin-mediated endocytosis, a liquid-like protein network catalyzes vesicle assembly. How do cells regulate these assemblies? Here we show that ubiquitin and endocytic proteins form a dynamic, mutually-reinforcing protein network in vitro and in live cells. To probe the impact of ubiquitylation on the dynamics of endocytosis, we engineered opto-genetic control over recruitment of proteins to nascent endocytic sites. While recruitment of wildtype proteins promoted endocytosis, recruitment of deubiquitylases, enzymes capable of removing ubiquitin, resulted in disassembly of endocytic sites within minutes. These results illustrate that ubiquitylation can regulate the fate of endocytic structures, elucidating a functional connection between protein condensates, endocytosis, and ubiquitin signaling.

cell biology↗

Harnessing Gradients for Self-Assembly of Peptide-Based Nanocapsules: A Pathway to Advanced Drug Delivery Systems

Biological systems often create materials with intricate structures to achieve specialized functions. In comparison, precise control of structures in man-made materials has been challenging. Here, we report a serendipitous discovery of insect cuticle peptides (ICPs) spontaneously forming nanocapsules through a single-step solvent exchange process, where the concentration gradient resulting from mixing of water and aceton drives the localization and self-assembly of the peptides into hollow nanocapsules. The underlying driving force is the intrinsic affinity of the peptides for a particular solvent concentration, while the diffusion of water and acetone creates a gradient interface that triggers peptide localization and self-assembly. This gradient-mediated self-assembly offers a transformative pathway towards next-generation drug delivery systems based on peptide nanocapsules.

bioengineering↗

Lipid droplets as substrates for protein phase separation

Membrane-associated protein phase separation plays critical roles in cell biology, driving essential cellular phenomena from immune signaling to membrane traffic. Importantly, by restricting diffusion to a two-dimensional surface, lipid bilayers can nucleate phase separation at far lower concentrations compared to those required for phase separation in solution. How might other intracellular lipid substrates, such as lipid droplets, contribute to nucleation of phase separation? Distinct from bilayer membranes, lipid droplets consist of a phospholipid monolayer surrounding a core of neutral lipids, and they are energy storage organelles that protect cells from lipotoxicity and oxidative stress. Here, we show that intrinsically disordered proteins can undergo phase separation on the surface of synthetic and cell-derived lipid droplets. Specifically, we find that model disordered domains, FUS LC and LAF1-RGG, separate into protein-rich and protein-depleted phases on the surfaces of lipid droplets. Owing to the hydrophobic nature of interactions between FUS LC proteins, increasing ionic strength drives an increase in its phase separation on droplet surfaces. The opposite is true for LAF1-RGG, owing to the electrostatic nature of its interprotein interactions. In both cases, protein-rich phases on the surfaces of synthetic and cell-derived lipid droplets demonstrate molecular mobility indicative of a liquid-like state. Our results show that lipid droplets can nucleate protein condensates, suggesting that protein phase separation could be key in organizing biological processes involving lipid droplets.

biophysics↗

SEQUENCE VS. STRUCTURE: DELVING DEEP INTO DATA DRIVEN PROTEIN FUNCTION PREDICTION

AO_SCPLOWBSTRACTC_SCPLOWPredicting protein function is a longstanding challenge that has significant scientific implications. The success of amino acid sequence-based learning methods depends on the relationship between sequence, structure, and function. However, recent advances in AlphaFold have led to highly accurate protein structure data becoming more readily available, prompting a fundamental question: given sufficient experimental and predicted structures, should we use structure-based learning methods instead of sequence-based learning methods for predicting protein function, given the intuition that a proteins structure has a closer relationship to its function than its amino acid sequence? To answer this question, we explore several key factors that affect function prediction accuracy. Firstly, we learn protein representations using state-of-the-art graph neural networks (GNNs) and compare graph construction(GC) methods at the residue and atomic levels. Secondly, we investigate whether protein structures generated by AlphaFold are as effective as experimental structures for function prediction when protein graphs are used as input. Finally, we compare the accuracy of sequence-only, structure-only, and sequence-structure fusion-based learning methods for predicting protein function. Additionally, we make several observations, provide useful tips, and share code and datasets to encourage further research and enhance reproducibility.

bioinformatics↗

Development of monoclonal antibody-based blocking ELISA for detecting SARS-CoV-2 exposure in animals

The global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a significant threat to public health. Besides humans, SARS-CoV-2 can infect several animal species. Highly sensitive and specific diagnostic reagents and assays are urgently needed for rapid detection and implementation of strategies for prevention and control of the infection in animals. In this study, we initially developed a panel of monoclonal antibodies (mAbs) against SARS-CoV-2 nucleocapsid (N) protein. To detect SARS-CoV-2 antibodies in a broad spectrum of animal species, a mAb-based bELISA was developed. Test validation using a set of animal serum samples with known infection status obtained an optimal percentage of inhibition (PI) cut-off value of 17.6% with diagnostic sensitivity of 97.8% and diagnostic specificity of 98.9%. The assay demonstrates high repeatability as determined by a low coefficient of variation (7.23%, 6.95%, and 5.15%) between-runs, within-run, and within-plate, respectively. Testing of samples collected over time from experimentally infected cats showed that the bELISA was able to detect seroconversion as early as 7 days post-infection. Subsequently, the bELISA was applied for testing pet animals with COVID-19-like symptoms and specific antibody responses were detected in two dogs. The panel of mAbs generated in this study provides a valuable tool for SARS-CoV-2 diagnostics and research. The mAb-based bELISA provides a serological test in aid of COVID-19 surveillance in animals. IMPORTANCEAntibody tests are commonly used as a diagnostic tool for detecting host immune response following infection. Serology (antibody) tests complement nucleic acid assays by providing a history of virus exposure, no matter symptoms developed from infection or the infection was asymptomatic. Serology tests for COVID-19 are in high demand, especially when the vaccines become available. They are important to determine the prevalence of the viral infection in a population and identify individuals who have been infected or vaccinated. ELISA is a simple and practically reliable serological test, which allows high-throughput implementation in surveillance studies. Several COVID-19 ELISA kits are available. However, they are mostly designed for human samples and species-specific secondary antibody is required for indirect ELISA format. This paper describes the development of an all species applicable monoclonal antibody (mAb)-based blocking ELISA to facilitate the detection and surveillance of COVID-19 in animals.

microbiology↗