Biology subjects

Dai, L.

Publications and source records attributed to Dai, L..

At least 19 recordsLinked to original sources

bioRxiv2026

FINDER converts zero-background kinetic fingerprinting into area-scalable attomolar biomarker detection

Background constrains analytical sensitivity: surveying larger sensor areas samples more analyte molecules but also accumulates false positives, limiting gains in detection performance. Here we introduce FINDER--Fluorogenic INstantaneous Digital Enumeration and Recognition--a single-molecule platform that combines kinetic fingerprinting with fluorogenic transient probes for rapid molecular classification under near-zero-background conditions. By suppressing both solution and surface-associated background at micromolar probe concentrations, FINDER classifies individual molecules within seconds-scale observation windows per field of view. This regime allows sensitivity to scale with surveyed sensor area, enabling amplification-free quantification of the miRNA cancer biomarker hsa-miR-16 with an 11 aM detection limit. FINDER further generalizes to HPV16 DNA biomarker detection, two-color RNA/DNA co-profiling, and rapid discrimination of clinically relevant EGFR single-nucleotide variants using multidimensional kinetic filtering. Rapid per-field classification permits tens of fields to be surveyed within minutes. By converting kinetic specificity into area-scalable sensitivity, FINDER enables semi-automated attomolar biomarker counting without amplification in practical workflows.

biophysics↗

bioRxiv2026

A Time-Sequenced Three-Drug-Loaded Microneedle Patch for the Prevention of Vein Graft Restenosis After Coronary Artery Bypass Grafting

Coronary artery bypass grafting (CABG) is the recommended treatment for severe coronary heart disease; however, restenosis of great saphenous vein grafts continues to limit long-term outcomes because of early thrombosis, mid-term intimal hyperplasia, and late atherosclerosis. To address these sequential pathological processes, this study develops a perivascular drug-loaded microneedle (MN) patch capable of controlled chronological release of tirofiban, rapamycin, and rosuvastatin. The MN patch exhibits uniform conical microneedles (height: 700-800 {micro}m), nanoparticle size of 125 nm, sufficient mechanical strength (1.07 N/needle) for venous intimal penetration, excellent biocompatibility, and no detectable cytotoxicity or hemolysis. In a mouse model of venous graft transplantation, the device significantly reduces early platelet thrombus formation (23.3% to 10%), alleviates mid-term intimal hyperplasia (intimal thickness: 0.84 mm to 0.45 mm at 4 weeks), and improves long-term graft patency with blood flow increasing from 13.1 to 65.8 mL/min at 32 weeks while reducing long-term mortality. Mechanistically, RNA sequencing and functional analyses demonstrate that excessive glycolysis-driven smooth muscle cell proliferation, coupled with abnormal endothelial cell apoptosis, constitutes the core mechanism underlying mid- to long-term restenosis, which the MN device effectively suppresses. This integrated MN patch provides a localised therapeutic strategy for preventing restenosis and improving long-term CABG outcomes. Table of Contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/726718v1_ufig1.gif" ALT="Figure 1"> View larger version (63K): org.highwire.dtl.DTLVardef@1de0e6borg.highwire.dtl.DTLVardef@184a846org.highwire.dtl.DTLVardef@43a50forg.highwire.dtl.DTLVardef@109bb85_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2026

Large-scale activity analysis of gut prophages reveals significantly active lineages in the human gut

Prophages dominate the human gut virome and their transition from lysogeny to lytic replication profoundly affects gut microbial community structure. However, the global activity landscape of gut prophages remains largely uncharted. Here, we developed a workflow to assess prophage activity across more than 30,000 gut bacterial isolates cultured in vitro under standard conditions. Using this approach, 4,033 prophages, corresponding to a small fraction (7.5%) of the overall prophage reservoir, were detected as active, indicating a high-lysogeny, low-activity landscape. Prophage activity varied markedly across host taxa, with Bacillota exhibiting notably elevated active rates. Active prophages derived from 183 viral families (vFAMs), 55 of which were assigned as significantly active (SA-vFAMs), including: SA-vFAM7, a novel, hyper-prevalent lineage with expanded host range into Tannerellaceae and substantial intra-lineage diversity; and Candidatus Mubacviridae (SA-vFAM1), a newly defined, hankyphage-inclusive, highly active Mu-like transposable phage family infecting Bacteroidales, characterized by conserved MuA-MuB operons and cross-family host range. Together, this work provides a large-scale, activity-integrated atlas of human gut prophages, demonstrating that prophage activity is driven by both host phylogeny and viral lineage identity, and establishing a foundational resource for understanding prophage ecology.

microbiology↗

bioRxiv2026

Pyruvate-driven hydrogen production promotes polyphenol bioconversion by gut bacteria

Gut microbial biotransformation of poorly absorbable polyphenols into bioactive, bioavailable metabolites is increasingly recognized as a key mechanism underlying their health benefits of polyphenols. Microbial ellagic acid (EA)-to-urolithin conversion represents a typical example, but the environmental factors that facilitate such metabolism remain underexplored. We discovered that urolithin production by a gut commensal bacterium, Gordonibacter urolithinfaciens (G. uro), is metabolically repressed by arginine. To overcome such limitations, we developed PhenolBoost Medium (PBM) that induces a metabolic shift by suppressing the arginine deiminase pathway while activating pyruvate metabolism and hydrogen production in G. uro, thereby driving urolithin dehydroxylation. Transcriptomic profiling and 13C-isotopic tracing analysis revealed that pyruvate metabolism in PBM upregulates hydrogenase expression, facilitating the dehydroxylation of EA. PBM also promoted the complete conversion of EA to urolithin A in G. uro-Enterocloster bolteae co-culture, and other polyphenol biotransformations. In addition, co-culturing G. uro with hydrogen-producing Bacteroides species significantly increased urolithin production. Furthermore, an arginine-limited, pyruvate-enriched dietary regimen proved effective in vivo, resulting in significantly higher urolithin production and bioavailability in a mouse model. Our findings reveal the critical role of hydrogen in facilitating polyphenol dehydroxylation, and offer a viable nutritional strategy for boosting microbial production of beneficial metabolites from polyphenols.

microbiology↗

bioRxiv2025

Neocortical temporal patterning by a two-layered regulatory network

In the developing neocortex, a diverse array of neurons with defined types and abundances are systematically generated by a limited population of radial glial progenitors (RGPs) as they undergo successive fate changes. The molecular regulation behind this intricate temporal patterning remains elusive. We undertook in-depth single-cell multi-omics analyses, discovering a two-layered regulatory framework at the core of this process. Central to this are global temporal regulators positioned above a temporal network, consisting of series of transcriptional factor (TF) hub groups under sequential state transitions. This temporal network operates not by restricting TF expressions to discrete temporal windows, but through coordinated transcriptional and chromatin-accessibility dynamics that modulate transient TF regulatory activity. Moreover, global temporal regulators specify the duration of each cascading stage and, consequently, the number of progenies generated at each stage. Loss of global temporal regulators protracts RGP lineage progression, whereas their increased activity accelerates it. These findings suggest a two-layer temporal regulatory system controlling RGP lineage progression and neural progeny output duality in mammalian neocortical development.

neuroscience↗

bioRxiv2025

Bio-synthesis of 15N-Labeled G-Quadruplexes to Investigate the Structure and Interactions in the Cell Lysate using Nuclear Magnetic Resonance

G-quadruplexes (G4) play key roles in biology, making it critical to understand their structure and ligand-binding behavior in cellular environments for advancing G4-targeted therapeutics. While in-cell nuclear magnetic resonance (NMR) is a powerful technique for studying G4 in situ, its application is limited by the challenge of producing isotope-labeled single-stranded DNA (ssDNA). Here, we introduce Restriction Endonuclease Digestion (RED), a simple and cost-effective method to generate 15N-labeled ssDNA. This approach combines molecular cloning and enzymatic design processing by propagating plasmids in E. coli cultured with 15NH4Cl, followed by double restriction digestion and isolation target 15N-ssDNA. Using RED, we produced milligram-scale quantities of 96%-enriched 15N-labeled human telomeric G4 ssDNA (wtTel23c, CTAGGG(TTAGGG)3), ideal for NMR analysis. The NMR spectra revealed that wtTel23c adopts G4 topology and undergoes multiple conformations of wtTel23c in potassium-containing solutions and in Xenopus laevis cell lysate. Interaction studies with the ligand TMPyP4 showed distinct binding profiles in cellular and dilute environments. In dilute solution, TMPyP4 binds to the top tetrad of wtTel23c, while it binds to the loop in cellular environments. The RED method offers an efficient strategy for producing stable isotope-labeled ssDNA, opening new avenues for studying G4 structures and their ligand interactions in complex biological contexts.

biochemistry↗

bioRxiv2025

Human and mouse regenerative macrophages enhance beta cell survival, function, and proliferation

Aims/hypothesisType 1 diabetes is an autoimmune disease caused by immune-mediated destruction of insulin-producing pancreatic beta cells. Interestingly, individuals with long-standing type 1 diabetes have residual beta cells, suggesting the existence of regenerative mechanisms that help maintain beta cell survival. Islet-resident macrophages have an important role in type 1 diabetes, and during disease progression can adopt a tissue-regenerating phenotype which may support beta cells. However, the specific roles of macrophages in beta cell survival, function, and proliferation remains poorly defined. This study aimed to elucidate how different macrophage subtypes influence beta cell survival, function, and proliferation. MethodsMouse and human islets were isolated from the pancreas and co-cultured in vitro with macrophages. To investigate whether macrophages enhance beta cell survival and function, beta cell apoptosis was measured using flow cytometry, and insulin secretion was assessed using a glucose-stimulated insulin secretion assay. We also examined whether macrophages further increased beta cell proliferation in the presence of harmine, a DYRK1A inhibitor. Finally, we evaluated the effect of islet co-culture on macrophage phenotype by flow cytometry and cytokine secretion analysis. ResultsWe found that regenerative, but not pro-inflammatory, macrophages enhanced beta cell survival and function through mechanisms that did not require direct cell contact. Direct contact between macrophages and islets further promoted a regenerative phenotype in macrophages, characterized by increased CD206 expression and secretion of anti-inflammatory factors. Additionally, regenerative macrophages promoted beta cell proliferation in the presence of harmine. ConclusionsOur findings demonstrate that regenerative macrophages support pancreatic beta cell survival, function, and proliferation. Harnessing the regenerative properties of macrophages could offer a novel strategy to promote beta cell survival and function, thereby improving outcomes for individuals with type 1 diabetes. Research in ContextWhat is already known about this subject? O_LIMacrophages are the predominant resident immune cells within pancreatic islets in non-diabetic individuals; they contribute to tissue homeostasis and immune surveillance. C_LIO_LIDepending on their activation state, macrophages can exert either beneficial (pro-regenerative) or harmful (pro-inflammatory) effects on beta cell function. C_LI What is the key question? O_LIHow do different macrophage subtypes regulate islet survival, regeneration, and function? C_LI What are the new findings? O_LICo-culturing mouse or human islets with regenerative macrophages enhanced beta cell survival and function. When added in the presence of a DYRK1A inhibitor (harmine), they also promoted beta cell proliferation. C_LIO_LIRegenerative macrophage-derived factors promoted mouse islet function via a contact independent mechanism. C_LIO_LIMouse islets enhanced the regenerative phenotype of macrophages. C_LI How might this impact on clinical practice in the foreseeable future? O_LILeveraging the regenerative potential of macrophages represents a novel therapeutic approach to enhance beta cells, ultimately improving outcomes for individuals with type 1 diabetes. C_LI

cell biology↗

bioRxiv2025

Riemann-GNN: Causal Reasoning on Hyperbolic Riemannian Manifolds for Interpretable Drug-Disease Prediction

The high cost and low success rate of de novo drug development have driven increasing interest in drug repurposing. Computational approaches to drug repurposing leverage large-scale biomedical knowledge graphs (KGs) to identify new indications for existing drugs. However, the structural heterogeneity, relation sparsity, and limited interpretability of current models remain significant challenges. In this study, we propose Riemann-GNN, an end-to-end framework that combines hyperbolic geometry, graph neural networks (GNNs), and causal inference for interpretable drug repurposing. Riemann-GNN embeds multi-relational biomedical KGs into a hyperbolic Riemannian manifold modeled by the Poincare ball, effectively capturing the hierarchical structure of biomedical entities. On top of this geometry, we introduce a causal reasoning module that extracts disease-centric subgraphs and applies intervention-based inference using structural causal models. This module provides mechanistic explanations for predicted drug-disease associations. We evaluate our model on PrimeKG, a comprehensive biomedical KG with over 129,000 nodes and 4 million edges, achieving AUROC = 0.971, AUPRC = 0.963, and Recall@20 = 0.847, significantly outperforming several state-of-the-art baselines. In a case study on amyotrophic lateral sclerosis (ALS), Riemann-GNN identifies 20 novel candidate drugs--such as Bosutinib, Masitinib, and Tamoxifen--and provides interpretable causal paths explaining their therapeutic relevance. Several predictions without existing ALS labels in the KG are supported by literature evidence, while others suggest new hypotheses for future validation. These results demonstrate the utility of integrating hyperbolic representation learning with causal semantics for robust and explainable biomedical AI.

bioinformatics↗

bioRxiv2025

AT1R and Integrin β3 Synergize to Drive Aortic Dissection via Non-Canonical Wnt/β-Catenin Signaling

Aortic dissection (AD), a life-threatening cardiovascular emergency, continues to impose high mortality due to insufficient therapeutic options, as monotherapy targeting angiotensin II type 1 receptor (AT1R) demonstrates limited clinical efficacy. Utilizing single-cell RNA sequencing, we identified integrin {beta}3 as a critical driver of AD progression, with expression levels positively correlated with disease severity. Histopathological validation in human AD specimens and a murine angiotensin II (AngII)-infusion model confirmed marked upregulation of integrin {beta}3 activation. Pharmacological blockade of integrin {beta}3 with Cyclo(-RGDfK) significantly attenuated aortic pathogenesis in vivo, reducing dissection incidence and aortic degeneration. Mechanistically, AngII-mediated AT1R activation induced formation of a receptor complex with integrin {beta}3, triggering its conformational activation. Transcriptomic profiling revealed that activated integrin {beta}3 potentiates vascular endothelial dysfunction by binding glycogen synthase kinase 3{beta} (GSK3{beta}), which stabilizes {beta}-catenin via a non-canonical Wnt signaling axis. This pathway drives endothelial barrier disruption, hallmarks of aortic wall destabilization in AD. Our findings unveil a previously unrecognized synergy between AT1R and integrin {beta}3, implicating aberrant Wnt/{beta}-catenin signaling as a nexus of endothelial injury in AD pathogenesis. These results advocate for a paradigm-shifting dual-therapeutic strategy concurrently targeting AT1R and integrin {beta}3 to restore vascular homeostasis, offering a mechanistically grounded approach to mitigate this lethal disease. This work bridges critical gaps in understanding AD pathophysiology and provides a transformative framework for precision therapeutics.

pharmacology and toxicology↗

bioRxiv2025

Cortactin regulates metastatic dormancy of circulating tumor cells by suppressing mTOR-dependent senescence

Metastatic dormancy often refers to the stable cell cycle arrest of disseminated tumor cells (DTCs) at distant sites. However, whether circulating tumor cells (CTCs) in the blood microenvironment can enter a dormant state prior to extravasation and becoming DTCs remains unclear. Using patient-derived melanoma CTC lines and animal explant models (CDX), we identified a previously unrecognized role of the cytoskeletal regulator cortactin (encoded by CTTN) in controlling mTOR/p53-dependent senescence and metastatic dormancy. Cortactin was localized to Rab7-postive endosomes and engaged in late endosomal tethering and homeostasis. The depletion of cortactin resulted in the accumulation of aberrantly enlarged late endosomal aggregates that were positive for Rab7 and mTOR. The mTOR protein complex was accumulated and activated within these abnormal vesicular structures, leading to robust p53 activation through phosphorylation at serine (S) 15 and S33 sites. Consequently, melanoma CTCs underwent G0/G1 cell cycle arrest and entered cellular senescence. This unusual oncogene-induced senescence (OIS) mechanism was characterized by SASP upregulation, {beta}-galactosidase activity, depletion of Ki-67 and Lamin B1, and elevated mitochondrial ROS (mtROS) levels. Notably, a positive feedback loop between p53 and mtROS was essential for maintaining stable senescence in CTCs. In preclinical CDX mouse models, we developed a sequential therapeutic strategy combining cortactin depletion with anti-Bcl-xL senolytic drugs. Such "One-two punch" treatment strategy effectively eliminated viable CTCs and suppressed metastatic tumor growth in vivo. Thus, targeting cortactin to induce CTC senescence, followed by senolytic therapy, may represent a promising strategy to block CTC-mediated metastatic progression.

cancer biology↗

bioRxiv2025

Chromato-kinetic fingerprinting enables multiomic digital counting of single disease biomarker molecules

Early and personalized intervention in complex diseases requires robust molecular diagnostics, yet the simultaneous detection of diverse biomarkers--microRNAs (miRNAs), mutant DNAs, and proteins--remains challenging due to low abundance and preprocessing incompatibilities. We present Biomarker Single-molecule Chromato-kinetic multi-Omics Profiling and Enumeration (Bio-SCOPE), a next-generation, triple-modality, multiplexed detection platform that integrates both chromatic and kinetic fingerprinting for molecular profiling through digital encoding. Bio-SCOPE achieves femtomolar sensitivity, single-base mismatch specificity, and minimal matrix interference, enabling precise, parallel quantification of up to six biomarkers in a single sample with single-molecule resolution. We demonstrate its versatility in accurately detecting low-abundance miRNA signatures from human tissues, identifying upregulated miRNAs in the plasma of prostate cancer patients, and measuring elevated interleukin-6 (IL-6) and hsa-miR-21 levels in cytokine release syndrome patients. By seamlessly integrating multiomic biomarker panels on a unified, high-precision platform, Bio-SCOPE provides a transformative tool for molecular diagnostics and precision medicine.

biophysics↗

bioRxiv2025

VZV gE Promotes STING Degradation via Midnolin-Proteasome Pathway to Inhibit cGAS-STING Signaling

Varicella-zoster virus (VZV) infects 85 million individuals annually and it is known for its intricate interplay with host cellular mechanisms, significantly impacting antiviral immune responses. Previous studies have highlighted the critical role of VZV glycoprotein E (gE) in virus-host interactions, but the precise mechanisms remain to be elucidated. Our results demonstrate that VZV gE interacts with STING, specifically through the gE (350-480aa) and STING (151-160aa) regions. This interaction predominantly involves incompletely glycosylated gE. Functional assays revealed that gE inhibits the cGAS-STING signaling pathway. gE enhances VZV proliferation and promotes STING degradation via the proteasome pathway, without affecting STING ubiquitination. We identified Midnolin as a mediator in this degradation process, with gE facilitating the interaction between STING and Midnolin. In vivo, gE expression in mice led to diminished antiviral responses upon HSV-1 infection, highlighting gEs role in modulating immune signaling. Our findings provide significant insights into VZVs evasion of host immune responses. By promoting STING degradation through an unconventional Midnolin-proteasome pathway, VZV gE effectively suppresses antiviral signaling, facilitating enhanced viral proliferation. The findings contribute significantly to the understanding of VZV pathogenesis and provide new therapeutic strategies against VZV.

microbiology↗

bioRxiv2024

Genome-wide Mapping Eukaryotic Open Chromatin Regions with Double-Stranded DNA Deaminase

A variety of methods such as ATAC-seq and CUT&Tag have been developed for probing chromatin states. However, enzymatic cleavage of DNA in these methods hinders their multi-omics integration with other DNA profiling techniques. Here, by extending our use of dsDNA deaminase (FOOtprinting with DeamInasE, FOODIE), we introduce two new methods for mapping Chromatin Open region by DeamInasE (ChrODIE) and histone modification by ANtibody-associated DeamInasE (ANDIE), respectively. Unlike cleavage-based methods, both ChrODIE and ANDIE leave genomic DNA after deamination unfragmented and amplifiable. This offers the potential for simultaneous or downstream integration with other genomic profiling methods, such as mapping 3D genome interactions.

genomics↗

bioRxiv2024

Time- and Dose-dependent Effects of CIGB-300 in the lung squamous cell carcinoma proteomics.

Proteome-wide scale in a dose- and time-depending setting is crucial in drug-regulated proteomics to fully understand the pharmacological mechanism of anticancer drugs as well as the identification of proteins suitable for drug response biomarkers. Here, we investigated the effect of the CIGB-300 anticancer peptide at IC50 and IC80 dose levels during 1 and 4 hours of treatment on squamous lung cancer cell (NCI-H226) proteome. A dose-dependent inhibitory effect of the global proteomics while slight change of the upregulated proteins was observed, by increasing CIGB-300 dose level. The biological processes that were more represented among the modulated proteins were those related to small molecule biosynthetic process, pyridine-containing compound metabolic process and nucleobase-containing small molecule metabolism. Importantly, NSCLC previously described biomarkers and Protein Kinase CK2 substrates were significantly modulated by treating both doses of CIGB-300. These proteins, which are associated with both metabolism and cell survival, reinforce the hypothesis of the therapeutic potential of CIGB-300 as anticancer treatment for squamous non-small cell lung cancer and merits be validated as CIGB-300 response biomarkers in NSCLC patients. Overall, our proteomics-guided strategy based on time and drug dose served not only to deep into the mechanism of action of CIGB-300 but also to identify candidate proteins for pharmacodynamic and drug response biomarkers.

cancer biology↗

bioRxiv2024

A CRISPR/SpCas9M-reporting system for efficient and rapid genome editing in Caulobacter crescentus

As members of the -proteobacteria group, Caulobacter crescentus and its relatives are known for their asymmetric life cycle and comprehensive applications in gene delivery, agricultural biotechnology, and the production of high-value compounds. However, genetic manipulations of these bacteria are often time-consuming and labor-intensive due to the lack of efficient genome editing tools. Here, we report a practical CRISPR/SpCas9M-reporting system that overcomes the limitations of SpCas9 expression, enabling efficient, markerless, and rapid genome editing in C. crescentus. As a demonstration, we successfully knocked out two genes encoding the scaffold proteins, achieving apparent editing efficiencies up to 80%. Key components, including the Cas protein, Cas inducer, sgRNA, homologous arms, and reporter, were systematically analyzed and optimized to enhance the editing efficiency or decrease the cell lethality. A nearly zero off-target ratio was observed after the curing of the editor plasmid in editing strains. Furthermore, we applied the CRISPR/SpCas9M-reporting system to two C. crescentus relatives, Agrobacterium fabrum and Sinorhizobium meliloti, establishing it as an efficient and reliable editing strategy. We anticipate that this system could be applied to other hard-to-edit organisms, accelerating both basic and applied research in -proteobacteria.

bioengineering↗

bioRxiv2024

Mechanistic model for epigenetic maintenance by methyl-CpG-binding domain proteins

DNA methylation is a fundamental element of epigenetic regulation that is governed by the MBD protein superfamily, a group of "readers" that share a highly conserved methyl-CpG-binding domain (MBD) and mediate chromatin remodeler recruitment, transcription regulation, and coordination of DNA and histone modification. Previous work has characterized the binding affinity and sequence selectivity of MBD-containing proteins toward palindromes of 5-methylcytosine (5mC) containing 5mCpG dinucleotides, often referred to as single symmetrically methylated CpG sites. However, little is known about how MBD binding is influenced by the prototypical local clustering of methylated CpG sites and the presence of DNA structural motifs encountered, e.g., during DNA replication and transcription. Here, we use Single-Molecule Kinetics through Equilibrium Poisson Sampling (SiMKEPS) to measure precise binding and dissociation rate constants of the MBD of human protein MBD1 to DNAs with varying patterns of multiple methylated CpG sites and diverse structural motifs. MBD binding is promoted by two major properties of its DNA substrates: 1) tandem (consecutive) symmetrically methylated CpG sites in double-stranded DNA and secondary structures in single-stranded DNA; and 2) DNA forks. Based on our findings, we propose a mechanistic model for how MBD proteins contribute to epigenetic boundary maintenance between transcriptionally silenced and active genome regions.

biophysics↗

bioRxiv2024

Islet amyloid disrupts MHC Class II antigen presentation and protects NOD mice from autoimmune diabetes.

Islet amyloid contributes to beta cell failure in type 2 diabetes through several mechanisms, one being the potent induction of local islet inflammation through activating inflammatory pathways in islet macrophages. We performed an unbiased phenotypic investigation of islet macrophages in the early stage of islet amyloid formation using single cell RNA sequencing of resident islet macrophages in mice with and without the amyloidogenic form of human islet amyloid polypeptide (hIAPP). This revealed that MHC Class II antigen presentation genes were strongly down-regulated in islet macrophages during islet amyloid formation. As islet amyloid has recently been reported in pancreases of people with type 1 diabetes, we sought to investigate the impact of islet amyloid in the NOD mouse model of type 1 diabetes. Both overexpression and physiological expression of hIAPP delayed diabetes in NOD mice relative to littermate controls, corresponding with decreased markers of antigen presentation and activation, as well as decreased immune cell infiltration in islets. Adoptive transfer studies showed that systemic autoimmune function remained intact and beta cells from hIAPP transgenic mice did not evade immune recognition by diabetogenic T cells, collectively indicating the protection from diabetes was mediated by localized disruption of antigen presentation in the pancreas. Consistent with this, incubation of dendritic cells with IAPP aggregates decreased MHC Class II surface expression and diminished antigen-specific T cell activation in vitro, through a phagocytosis-dependent mechanism. Collectively our data show that despite the well-established pro-inflammatory response of macrophages to IAPP aggregates, the uptake of IAPP aggregates during early amyloid formation also disrupts MHC Class II antigen presentation and slows beta cell autoimmunity.

immunology↗

bioRxiv2024

Zinc finger transcription factors BnaSTOP2s regulate sulfur metabolism and confer resistance to Sclerotinia sclerotiorum in Brassica napus

Rapeseed (Brassica napus L.) has a high sulfur requirement for optimal growth, development, and pathogen resistance. In this study, we identified zinc finger transcription factors, BnaSTOP2s, that play key roles in sulfur metabolism and Sclerotinia sclerotiorum resistance. First, our results suggested that BnaSTOP2s are involved in sulfur as evidenced from extensive protein interaction screening. Knockout of BnaSTOP2s reduced the response sensitivity in both sulfur-deficient and sulfur-excessive conditions by promoting the elongation of primary roots of seedlings. Furthermore, the content of essential sulfur-containing metabolites, including glucosinolate and glutathione, were substantially down-regulated in roots and leaves of Bnastop2 mutants, which is consistent with the significantly lowered transcriptional levels of key players of GSL synthesis and transportation, BnaMYB28s and BnaGTR2s, respectively. Through comprehensive RNA-seq analysis, we revealed the substantial effect of BnaSTOP2s on sulfur metabolism from source to sink. Additionally, we observed a significant decrease while increase in leaf lesion sizes of the BnaSTOP2-OE and Bnastop2 mutants, respectively, when compared to the wild type during Sclerotinia sclerotiorum infection, suggesting the vital role of BnaSTOP2 in plant defense response. Overall, our findings highlight that BnaSTOP2s seems to be global regulators of sulfur metabolism and confer resistance to Sclerotinia sclerotiorum infection in B. napus.

plant biology↗