Biology subjects

Lin, X.

Publications and source records attributed to Lin, X..

At least 91 records · Page 5Linked to original sources

bioRxiv2025

AtlasAgent: Vision language model and Agent-guided Framework for Evaluation of Atlas-scale Single-cell Integration

As single-cell omics transitions into the era of AI-virtual cells (AIVC), where large-scale single-cell data integration becomes prevalent, the computational demands of integration evaluation emerge as critical scalability bottlenecks. Traditional integration evaluation pipelines, requiring metrics like k-nearest-neighbor batch effect test (kBET) and Local Inverse Simpsons Index (iLISI) employed by state-of-the-art scIB method, often demand large computational resources and long runtimes, making them infeasible for large scale integration studies. Herein, we present AtlasAgent, the first vision-language model (VLM)-powered and AI agent framework to accelerate atlas-scale integration evaluation at unprecedented speed and scale. We systematically evaluate batch correction quality, biological signal preservation and overcorrection risks using chain-of-thought reasoning in conjunction with few-shot and zero-shot prompting strategies. AtlasAgent completes evaluation within 32 seconds, in contrast to scIBs runtime of 5.55 hours in GPU, while identifying the scIB-determint best integration methods within the top-3 in 88.3% of the time, lowering evaluation time from hours to seconds while preserving alignment with domain expert reasoning. AtlasAgent pioneers the use of VLMs to realize scalable and rapid integration evaluation at atlas scale.

bioinformatics↗

bioRxiv2025

Complementary cortical and thalamic contributions to cell-type-specific striatal activity dynamics during movement

Coordinated motor behavior emerges from information flow across brain regions. How long-range inputs drive cell-type-specific activity within motor circuits remains unclear. The dorsolateral striatum (DLS) contains direct- and indirect-pathway medium spiny neurons (dMSNs and iMSNs) with distinct roles in movement control. In mice performing skilled locomotion, we recorded from dMSNs, iMSNs, and their cortical and thalamic inputs identified by monosynaptic rabies tracing. An RNN classifier and clustering analysis revealed functionally heterogeneous subpopulations in each population, with dMSNs preferentially activated at movement onset and offset, and iMSNs during execution. Cortical and thalamic inputs were preferentially activated during onset/offset and execution, respectively, though dMSN- and iMSN-projecting neurons in each region showed similar patterns. Locomotion phase-specific rhythmic activity was found in a subset of thalamic dMSN-projecting neurons and dMSNs. Cortex or thalamus inactivation reduced MSN activity. These findings suggest that corticostriatal and thalamostriatal inputs convey complementary motor signals via shared and cell-type-specific pathways.

neuroscience↗

bioRxiv2025

PromptBio: A Multi-Agent AI Platform for Bioinformatics Data Analysis

PromptBio is a modular AI platform for scalable, reproducible, and user-adaptable bioinformatics analysis, powered by generative AI and natural language interaction. It supports three complementary modes of analysis designed to meet diverse research needs. PromptGenie is a multi-agent system that enables stepwise, human-in-the-loop workflows using prevalidated domain-standard tools. Within PromptGenie, specialized agents--including DataAgent, OmicsAgent, AnalysisAgent, and QAgent--collaborate to manage tasks such as data ingestion, pipeline execution, statistical analysis, and interactive summarization. DiscoverFlow provides integrated, automated workflows for large-scale multi-omics analysis, offering end-to-end execution and streamlined orchestration. ToolsGenie complements these modes by dynamically generating executable bioinformatics code for custom, user-defined analyses, enabling flexibility beyond standardized workflows. PromptGenie and DiscoverFlow leverage a suite of domain-specific tools, including Omics Tools for standardized omics pipelines, Analysis Tools for downstream statistical interpretation, and MLGenie for machine learning and multi-omics modeling. We present the design, capabilities, and validation of these components, highlight their integration into automated and customizable workflows, and discuss extensibility, monitoring, and compliance. PromptBio aims to democratize high-throughput bioinformatics through a large language model-powered, natural language understanding, workflow generation and agent orchestration.

bioinformatics↗

bioRxiv2025

Secondary structure transitions and dual PIP2 binding define cardiac KCNQ1-KCNE1 channel gating

The KCNQ1+KCNE1 potassium channel complex forms the slow delayed rectifier current (IKs) critical for cardiac repolarization. Loss-of-function variants in KCNQ1 and KCNE1 cause long QT syndrome types 1 and 5 (LQT1/LQT5), accounting for over one-third of clinical LQTS cases. Despite prior structural work on KCNQ1 and KCNQ1+KCNE3, the structural basis of KCNQ1+KCNE1 remains unresolved. Using cryo-EM and electrophysiology, we determined high-resolution (2.5-3.4 [A]) structures of human KCNQ1+KCNE1 in both closed and open states. KCNE1 occupies a pivotal position at the interface of three KCNQ1 subunits, inducing seven "helix-to-loop" transitions in KCNQ1 transmembrane segments. These structural rearrangements: 1) stabilize the closed pore and the conformation of the intermediate voltage-sensing domain, thereby determining channel gating, ion permeation, and single channel conductance; 2) enable a dual-PIP2 modulation mechanism, where one PIP2 occupies the canonical site, while the second PIP2 bridges the S4-S5 linker, KCNE1, and the adjacent S6, stabilizing channel opening; 3) create a fenestration capable of binding compounds specific for KCNQ1+KCNE1 (e.g., AC-1). Together, these findings reveal a previously unrecognized large-scale secondary structural transition during ion channel gating that fine-tunes IKs function and provides a foundation for targeted LQTS therapy development.

biophysics↗

bioRxiv2025

The structural basis of cold sensitivity

Thermosensitive TRP ion channels enable somatosensory nerve fibers to detect changes in our thermal environment over a wide physiologic range 1-3. In mammals, the menthol receptor, TRPM8, is activated by temperatures below [~]26{degrees}C and is essential for the perception of cold or chemical cooling agents 4-6. A fascinating, yet still unachieved goal is to elucidate structural mechanisms whereby TRPM8 or other thermosensitive channels are gated by changes in ambient temperature. Recent studies using cryogenic electron microscopy (cryo-EM) have attempted to address this challenging question but are limited by difficulties in visualizing temperature-evoked conformational substates or assessing the energetic landscape governing gating transitions 7,8. Here, we close this gap by using cryo-EM to visualize TRPM8 channels in cellular membranes, where bona fide menthol- and cold-evoked open states are captured. We identify a novel semi-swapped architecture in which interdigitation of channel subunits is substantially rearranged following repositioning of the S6 transmembrane helix and elements of the pore region. By combining this structural analysis with thermodynamic measurements using hydrogen-deuterium exchange mass spectrometry (HDX-MS), we are able to pinpoint the pore and TRP helices as key regions undergoing stimulus-evoked conformational dynamics that drive channel gating. Structural mechanisms associated with activation are validated by comparison of human TRPM8 with the menthol-sensitive, but relatively cold-insensitive avian orthologue. We propose a free energy landscape to explain channel gating by cold or cooling agents.

biophysics↗

bioRxiv2025

Inhibiting RhoA Activation via GDP-state Stabilization to Relieve Heart Failure

High rates of heart failure (HF) morbidity and mortality have made targeting myocardial remodeling--particularly hypertrophy and fibrosis--a key therapeutic focus. RhoA, which regulates cytoskeletal reorganization and cell migration, plays a role in this process. However, RhoA has long been considered "undruggable", due to its strong binding to its endogenous substrates, GDP/GTP, and the lack of well-defined pockets for drug targeting. Here, we discovered a cryptic pocket proximate to GDP within RhoA and identified a natural product, AH001, binds here and interacts with GDP, stabilizing RhoAs interaction with its endogenous inhibitor, RhoGDI. AH001 reduced the downstream MRTFA nuclear translocation and downregulated fibrosis/hypertrophy proteins. Consequently, AH001 mitigated myocardial remodeling in multiple HF animal models, and in the 3D myocardial tissue model. Our findings highlight the therapeutic potential of inhibiting RhoA activation in myocardial remodeling, ultimately targeting HF, and offer a promising avenue for developing reversible inhibitors against undruggable GTPases.

pharmacology and toxicology↗

bioRxiv2025

Biophysical modeling for accurate T cell specificity prediction of viral and tumor antigens

Accurate predictions of T cell receptor (TCR) specificity remain an important open problem in immunology, with broad implications for vaccine design, optimal immunotherapy, and improved management of autoimmune diseases. However, diversity in peptide antigens and TCR sequences at the level of individual patient repertoires remains a formidable computational challenge. Here, we develop a joint experimental and computational approach for predicting the antigen specificity of clinically-derived TCR sequences. Our model is trained on a combination of experimentally pre-identified and in silico-predicted TCR-pMHC structures using AlphaFold3. We apply our structural model in the clinical setting of hematopoietic stem cell transplant (HSCT) and demonstrate that our model is able to effectively discern the specificity of previously unseen donor and patient-derived TCR sequences against tumor associated and viral antigens. Model performance was further enhanced through the integration of sequence-based clustering and structurally diverse training templates. Our results highlight the predictive capabilities of structurally guided machine learning frameworks, trained on a minority test dataset, for antigen specificity prediction on unseen TCR sequences and their potential impact on a wide range of immunological applications.

immunology↗

bioRxiv2025

Structural insights into VRC01-class bnAb precursors with diverse light chains elicited in the IAVI G001 human vaccine trial

The development of germline-targeting vaccines represents a potentially transformative strategy to elicit broadly neutralizing antibodies (bnAbs) against HIV and other antigenically diverse pathogens. Here, we report on structural characterization of vaccine-elicited VRC01-class bnAb precursors in the IAVI G001 Phase 1 clinical trial with the eOD-GT8 60mer nanoparticle as immunogen. High-resolution X-ray structures of eOD-GT8 monomer complexed with Fabs of five VRC01-class bnAb precursors with >90% germline identity revealed a conserved mode of binding to the HIV CD4-binding site (CD4bs) via IGHV1-2-encoded heavy chains, mirroring mature bnAb interactions. The light-chain V-gene diversity emulated VRC01 bnAbs and stabilized antigen engagement, while their conserved five-residue LCDR3 motifs prevented steric clashes. Notably, the VRC01-class bnAb precursors accommodated the N276 glycan, a key barrier in HIV Env recognition, through structural rearrangements in HCDR3 or LCDR1, despite its absence in the immunogen. Surface Plasmon Resonance (SPR) analysis showed that 87% of elicited antibodies retained glycan binding capacity, albeit with reduced affinity. These findings validate the ability of eOD-GT8 60mer nanoparticles to prime VRC01-class bnAb precursors with native-like paratopes but with intrinsic glycan adaptability. Structural mimicry of mature bnAbs was observed even with limited somatic hypermutation, indicating that critical features are encoded in the germline repertoire. The structures highlight how germline-encoded features drive bnAb-like recognition at early stages. This work provides molecular evidence supporting germline-targeting in humans and provides guidance for designing booster immunogens to shepherd affinity maturation toward broad neutralization.

immunology↗

bioRxiv2025

Cryo-EM structure of plant urea transporter DUR3 reveals essential role of C-terminal domain in tetramer assembly and insights into proton-coupled transport

Nitrogen pollution, caused by the overuse of nitrogen-fertilizers such as urea in agricultural production, has become a serious problem that threatens both the environment and human health. Improving the nitrogen use efficiency of crops is an important approach to reduce fertilizer use. DUR3, a high-affinity urea transporter, enables plants to acquire urea from natural or agricultural soils with low urea concentrations and has been proposed as a promising target for engineering crops to improve nitrogen-fertilizer use efficiency. Despite extensive studies for more than 20 years, the structure, substrate recognition and transport mechanism of DUR3 have remained unknown. Here we report the cryo-EM structure of maize DUR3 (ZmDUR3) at 3.41 [A] resolution. ZmDUR3 adopts an amino acid-polyamine-organocation (APC) superfamily fold and is structurally distinct from animal facilitative urea transporters. Our structure provides important insights into urea recognition by DUR3 and suggests that a pair of acidic residues is potentially involved in proton coupling during urea transport. Furthermore, our structural and functional studies indicate that DUR3 assembles into a tetramer and tetramer formation is important for its function. Our results pave the way for engineering plant DUR3 protein for applications in sustainable agricultural production.

plant biology↗

bioRxiv2025

Plastic-elastomer heterostructure for robust flexible brain-computer interfaces

Electronics for neural signal recording must be robust across multiple and deep brain regions while preserving tissue-level flexibility to ensure stable tracking over months or years. However, existing electronics cannot simultaneously achieve robustness and tissue-level flexibility, limiting their potential for customizable and scalable neuroscience research and clinical applications. Here, we introduce FlexiSoft, an electronic platform based on a plastic-elastomer heterostructure that uniquely integrates mechanical robustness and tissue-level flexibility. Compared to conventional flexible electronics of similar thickness, the FlexiSoft platform demonstrates an order-of- magnitude improvement in both mechanical robustness (critical energy release rate) and flexibility (flexural rigidity). Leveraging these mechanical advantages, we developed FlexiSoft probe for robust implantation, demonstrated by its ability to withstand repeated insertion and removal, as well as to reach centimeter-scale depths comparable to those in the human brain. The platform enables long-term recording from the same neurons across the hippocampus (HPC) and primary motor cortex (M1) during a months-long motor learning task, thereby revealing long-term dynamic changes in neuronal firing patterns. Additionally, FlexiSofts unique robustness and flexibility enable curved implantation routes, opening new directions of customizable implantation pathways. In summary, we present FlexiSoft as a novel, robust, and tissue-level flexible heterostructure electronics platform that advances flexible brain-computer interfaces (BCIs) with strong translational potential for neuroscience and clinical applications.

bioengineering↗

bioRxiv2025

Miniaturized and accessible functional ultrasound imaging system for freely moving mice

Functional ultrasound (fUS) imaging provides brain-wide activity maps with high spatiotemporal resolution and deep penetration, positioning it as a key technology for future non-invasive brain-computer interfaces (BCIs). Realizing this potential, particularly for chronic BCI applications requiring long-term monitoring in naturalistic settings, critically depends on significant system miniaturization to overcome the cost and complexity limitations of current platforms. Addressing this challenge, we present mini-fUS, a miniaturized, cost-effective fUS platform engineered for accessibility without compromising core performance for demanding neuroscience research. The system features a compact transmit-receiver, low-noise power supply, and high-speed data transfer, achieving pulse repetition frequencies up to 5 kHz with negligible jitter. Real-time GPU-accelerated beamforming and singular value decomposition (SVD) enable whole-brain activity mapping, demonstrated here in freely moving mice at up to 3.57 Hz with [~]100 {micro}m spatial resolution and 15 mm penetration depth. Validated through recordings of brain activity during sensory stimulation, anesthesia, and behavior, this design defines a practical hardware-software framework for fUS. By significantly improving accessibility and enabling robust monitoring in mobile subjects, this work advances the development of fUS for both fundamental research and future BCI technologies, while clarifying essential fUS operational principles.

neuroscience↗

bioRxiv2025

Two telomere-to-telomere, gap-free genome assemblies and comparisons revealed the conserved key genes associated with sugar accumulation in Rubus genus

For the first time, we assembled two highly continuous, completely gap-free reference genomes of the Rubus subgenus: Rubus hirsutus Thunb. Penglei (XMM) and Rubus eustephanos Focke ex Diels Dahongpao (DHP), which are widely distributed in southern China with similar phenotypic traits (Figures 1A, 1B, and Figure S1), yet ripe fruits display distinct sugar accumulation levels (Table S1), making them ideal candidates for investigating the mechanisms underlying sugar accumulation in the Rubus genus. The XMM (213.53 Mb, 28,204 genes) and DHP (218.26 Mb, 28,569 genes) genomes exhibit close evolutionary relationships, diverging approximately 3.21 Mya. Comparative genomics identified extensive synteny, interspecific structural variations (translocations, inversions, segmental duplications), and presence/absence variation (PAV). Using Hi-C interaction heatmaps and Sanger sequencing, we validated interspecific structural inversions. Additionally, we identified a sugar transporter gene (MFS1), which is present in XMM but absent in DHP. Combined analysis of the gene family expansion/contraction and transcriptome identified two conserved key genes (RhSTP13 and RhSTP7) associated with sugar accumulation in Rubus genus and displayed distinct roles through transient expression assay. To facilitate functional genomics study, we also established a comprehensive Rubus database, RubusDB, a freely accessible repository consolidating all genomic, transcriptomic and phenotypic data of Rubus genus. These findings provide a foundational framework for elucidating the genetic basis of sugar accumulation, genome diversification, and trait improvement in Rubus species. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=170 SRC="FIGDIR/small/646780v2_fig1.gif" ALT="Figure 1"> View larger version (72K): org.highwire.dtl.DTLVardef@1baca20org.highwire.dtl.DTLVardef@2c01eaorg.highwire.dtl.DTLVardef@131dc00org.highwire.dtl.DTLVardef@62a04f_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFIGURE 1.C_FLOATNO Phenotypic characterization, de novo genome assemblies, variation, and evolution of Rubus hirsutus Thunb. Penglei (XMM) and Rubus eustephanos Focke ex Diels Dahongpao (DHP). (A) Illustration of XMM whole plants, stem, flower bud and flower, respectively. (B) Illustration of DHP whole plants, stem, flower bud and flower, respectively. (C) The chromosome karyotype analysis of XMM. Bar = 10 {micro}m. (D) Circular diagram of XMM and DHP reference genomes. (a) Chromosomes are represented by centromeres (dark red) and telomeres (blue); (b) CEN18 density; (c) CEN17 density; (d) Gene density; (e) TE density; (f) PAV density; (g) SNP density; (h) Collinear lines at the center of diagram highlight homoeologous chromosomes relationships and non-homoeologous regions. (E) Genomic alignments between XMM and DHP. Inversions, duplications and translocations are marked with orange, blue and green ribbons, respectively. (F) Identification of large inversions in chromosome 7 between XMM and DHP. The three heatmaps show the chromatin interaction matrix, including mapping Hi-C data of DHP against DHP genome (left), mapping Hi-C data of DHP against XMM genome (middle) and mapping Hi-C data of XMM against XMM genome (right). The lower panel illustrates gene alignments between XMM and DHP. (G) Synteny, structural rearrangements, monomer, and identity distribution in the 16-20 Mbp region of chromosome 6 between XMM and DHP. (H) Local genome synteny of chromosome 5, with a structural variation that is present only in XMM. The PAV region includes a gene related to sugar transporter (MFS1, XMM05G025540). (I) Gene-level matchings of MFS genes in the PAVs region between XMM and DHP. (J) Phylogenetic relationships and divergence times between raspberries and other Rosaceae species. The black numbers close to the divergence nodes indicate the divergence times and the red bars represent the 95% confidence intervals. The red and black numbers indicate expanded and contracted ortholog groups at the corresponding node. Scale bar corresponds to 10 Mya. C_FIG

genomics↗

bioRxiv2025

AI-Driven Efficient De Novo design of GLP-1RAs with Extended Half-Life and Enhanced Efficacy

Peptide drug has revolutionized modern therapeutics, offering novel treatment avenues for various diseases. However, low efficacy, time consumption, and high cost hinder peptide drug design and discovery. We present an efficientin approach that integrates deep learning-based protein design with efficient functional screening, enabling the rapid design of biotechnologically important peptides with improved the stability and efficacy. We designed 10,000 de novo GLP-1 receptor agonists (GLP-1RAs), of which 60 met the stability, efficacy, and diversity criteria in the vitral functional screening. In vitro validation revealed a 62% success rate, while in vivo experiment demonstrated that two designed GLP-1RAs exhibited significantly extended half-lives, approximately three times longer than Semaglutide. In diabetic and obesity mouse models, the most competitive candidate showed superior therapeutic efficacy over Semaglutide. Our AI driven peptide design pipline integrats protein design, functional screening, and experiment validation, reducing the number of iterations required to find novel peptide candidates. The entire process, from design to screening, can be completed in a single cycle within two weeks.

bioengineering↗

bioRxiv2025

Using lightsheet microscopy to investigate the initial lymphatic network in the murine knee joints

Introduction. Lymphatic vasculature in mouse joints is difficult to study due to its vast anatomical variation. We reported increased lymphatic capillaries in post-traumatic OA (PTOA) murine joint based on 2D immunostaining. However, a gap of knowledge with this approach is that histology highly subjected to histological sampling, which might not be appropriate for a highly variable system such as the lymphatic vasculature. We hypothesize that using lightsheet microscopy would reveal the detailed structure of the initial lymphatic network. Methods. We established lightsheet imaging protocol and four quantifiable outcome parameters for visualizing and analyzing the initial lymphatic network in young C57/B6 wild type mouse knees. Lymphatic vessels were identified by staining samples with lymphatic endothelial marker LYVE1. We validated our lightsheet imaging protocol in mouse knee joints following PTOA surgery and knee joints received sham operation. Results. We used the histological landmarks of growth plates and menisci shape for consistent data collection for the 3D reconstruction of initial lymphatic network. Comparing to sham joints, PTOA joints have less mean branches length (58.91{+/-} 6.50 vs. 146.29 {+/-} 2.48 m in sham, p<0.0001), and mean branch diameter (12.25{+/-} 0.80] vs. 28.51 {+/-} 4.99 m in sham, p=0.0051), but higher total branching points (378{+/-} 239 vs. 69 {+/-} 17 m in sham, p=0.020), and total initial lymphatic network volume (51247{+/-} 14239 vs. 1019289 {+/-} 544458 m3 in sham, p=0.037). Conclusion. Lightsheet imaging of murine knee joints is a powerful and promising tool to study the joint lymphatic system and arthritis. Similar to previous report, the PTOA joint has increased branching with smaller and shorter branches.

cell biology↗

bioRxiv2025

SuperMetal: A Generative AI Framework for Rapid and Precise Metal Ion Location Prediction in Proteins

Metal ions, as abundant and vital cofactors in numerous proteins, are crucial for enzymatic activities and protein interactions. Given their pivotal role and catalytic efficiency, accurately and efficiently identifying metal-binding sites is fundamental to elucidating their biological functions and has significant implications for protein engineering and drug discovery. To address this challenge, we present SuperMetal, a generative AI framework that leverages a score-based diffusion model coupled with a confidence model to predict metal-binding sites in proteins with high precision and efficiency. Using zinc ions as an example, SuperMetal outperforms existing state-of-the-art models, achieving a precision of 94 % and coverage of 90 %, with zinc ions localization within 0.52 {+/-} 0.55 [A] of experimentally determined positions, thus marking a substantial advance in metal-binding site prediction. Furthermore, SuperMetal demonstrates rapid prediction capabilities (under 10 seconds for proteins with[~] 2000 residues) and remains minimally affected by increases in protein size. Notably, SuperMetal does not require prior knowledge of the number of metal ions--unlike AlphaFold 3, which depends on this information. Additionally, SuperMetal can be readily adapted to other metal ions or repurposed as a probe framework to identify other types of binding sites, such as protein-binding pockets.

bioinformatics↗

bioRxiv2025

Tracing LYVE1+ peritoneal fluid macrophages unveils two paths to resident macrophage repopulation with differing reliance on monocytes

Mouse resident peritoneal macrophages, called large cavity macrophages (LCM), arise from embryonic progenitors that proliferate as mature, CD73+Gata6+ tissue-specialized macrophages. After injury from irradiation or inflammation, monocytes are thought to replenish CD73+Gata6+ LCMs through a CD73-LYVE1+ LCM intermediate. Here, we show that CD73-LYVE1+ LCMs indeed yield Gata6+CD73+ LCMs through integrin-mediated interactions with mesothelial surfaces. CD73-LYVE1+ LCM repopulation of the peritoneum was reliant upon and quantitatively proportional to recruited monocytes. Unexpectedly, fate mapping indicated that only [~]10% of Gata6-dependent LCMs that repopulated the peritoneum after injury depended on the LYVE1+ LCM stage. Further supporting nonoverlapping lifecycles of CD73-LYVE1+ and CD73+Gata6+ LCMs, in mice bearing a paucity of monocytes, Gata6+CD73+ LCMs rebounded after ablative irradiation substantially more efficiently than their presumed LYVE1+ or CD73- LCM upstream precursors. Thus, after inflammatory insult, two temporally parallel pathways, each generating distinct differentiation intermediates with varying dependencies on monocytes, contribute to the replenish hment of Gata6+ resident peritoneal macrophages.

immunology↗

bioRxiv2025

Tarloxotinib targets tumor hypoxia to improve therapeutic efficacy of immune checkpoint inhibition in a TLR9 dependent manner

Immune checkpoint inhibitors can elicit deep and durable immune responses although most cancer patients fail to experience long-term remission. There is consensus that tumor hypoxia coordinates a multitude of underlying resistance mechanisms that contribute to treatment failure. Here we show that the clinical-stage hypoxia-activated prodrug tarloxotinib lowers tumor hypoxia 8-fold in the EGFR-dependent MB49 syngeneic tumor model, attracting a effector CD8+ T cell infiltrate into an oxygen enriched tumor microenvironment, leading to potentiation of checkpoint inhibitor activity. Various methodologies, including CD8+ T cell depletion and exogenous T cell priming confirmed that tarloxotinib has a positive impact on the function of activated CD8+ T cells. Whilst anti-PD-L1, anti-PD-1 and anti-CTLA-4 treatments all benefited from the remodeled tumor microenvironment, anti-PD-L1 was most responsive to tarloxotinib coadministration, providing a 100% complete response rate and >360% improvement in tumor growth delay (day 19; p<0.0001). This robust interaction was associated with MB49 tumor enrichment of CD8+ T cell infiltrate from 8% to 43% of the total CD45+ population. To further understand these promising observations, comparative RNA transcript analysis of 770 cancer/immune related genes in naive and tarloxotinib treated tumors highlighted the strong induction of gene clusters related to co-stimulatory signaling, cytokine/chemokine signaling, interferon signaling, immune cell adhesion/migration, antigen presentation and the lymphoid/myeloid compartments. Serum protein analysis confirmed upregulation of a mixture of cytokines/chemokines, including IL-6, IL-12p40, IFN{gamma}, G-CSF and MIP-1{beta}, amongst others. The source of this broad immunogenic response was identified as toll-like receptor 9 (TLR9) dependent, with the positive interaction between anti-PD-L1 and tarloxotinib blocked in MyD88 or TLR9 knockout mice. Further, the observed therapeutic interaction was still evident in MC38 and EG7.OVA syngeneic tumor models, both refractory to tarloxotinib by virtue of EGFR-signal independence. Consistent with the clinical experience of minimal systemic toxicities related to EGFR inhibition (e.g. diarrhea), mouse body weight loss was minimal across all in vivo studies and histopathology screening for evidence of lung fibrosis proved negative. Tarloxotinib therefore represents a systemically administered small molecule with an established clinical safety profile that is capable of activating TLR9 signaling within tumors whilst remodeling the microenvironment to facilitate efficacy of checkpoint blockade. What is already known on this topicSolid tumor resistance to immune checkpoint inhibitors (ICI) is orchestrated through a diverse collection of hypoxia-driven mechanisms. In preclinical models modifying the tumor microenvironment (TME) to lessen hypoxia typically improves responses to ICI. What this study addsTarloxotinib is a hypoxia-activated prodrug (HAP) of an irreversible EGFR/HER2 TKI that profoundly remodels the TME, both eliminating tumor hypoxia and elevating cytokine/chemokine production via a TLR9 dependent effect. Together, this results in a marked tumor influx of activated CD8+ T cells (and other TILs), that results in major improvements in the efficacy of ICIs, particularly anti-PD-L1. How this study might affect research, practice or policyTarloxotinib is the first example of a tumor-targeted small molecule TLR9 stimulant that restores ICI sensitivity in a range of syngeneic tumor models. Phase I/II data has demonstrated that tarloxotinib is well tolerated, with few EGFR-dependent (on-target) side-effects, reflecting minimization of normal tissue exposure with the tumor-targeted HAP approach. Importantly, it also optimizes tumor selective exposure, offering a compelling clinical rationale for evaluation of this combination in cancer patients experiencing ICI relapse or resistance.

immunology↗

bioRxiv2025

TAC-C uncovers open chromatin interaction in crops and SPL-mediated photosynthesis regulation

Cis-regulatory elements (CREs) direct precise gene expression for development and environmental response, yet their spatial organization in crops is largely unknown. We introduce Transposase-Accessible Chromosome Conformation Capture (TAC-C), a method integrating ATAC-seq and Hi-C to capture fine-scale chromatin interactions in four major crops: rice, sorghum, maize, and wheat. TAC-C reveals that chromatin interaction frequency aligns with genome size and gene expression, exhibiting distinct loop structures between C3 and C4 plants, particularly in C4-specific enzymes coding genes. Integrating chromatin structure with population genetics data highlights that chromatin loops connect distal regulatory elements to phenotypic variation. Asymmetrical open chromatin interactions among subgenomes, driven by transposon insertions and sequence variations, contribute to biased homoeolog expression. Furthermore, TaSPL7/15 regulate photosynthesis-related genes through chromatin interactions, with enhanced photosynthetic efficiency and starch content in Taspl7&15 mutant. TAC-C provides new insights into the spatial organization of regulatory elements in crops, especially for SPL-mediated photosynthesis regulation in wheat. TeaserTAC-C Reveals Chromatin Interactions and SPL-Mediated Photosynthesis Regulation in Crops.

plant biology↗