Biology subjects

Han, J.

Publications and source records attributed to Han, J..

At least 73 records · Page 4Linked to original sources

bioRxiv2026

A hypothalamo-septo-hippocampal circuit for REM sleep-dependent consolidation of social memory

REM sleep constitutes a critical window for memory consolidation, yet the brain circuits orchestrating this process remain incompletely defined. Here, we identify a lateral supramammillary nucleus (SuM)-medial septum (MS) projection as a REM sleep-specialized pathway essential for hippocampal memory consolidation. Fiber photometry and optrode recordings revealed that lateral SuM-MS projecting neurons were selectively active during REM sleep. REM-specific optogenetic silencing of this projection impaired consolidation of both social and contextual fear memories. Crucially, silencing of its downstream target, the MS-CA2 pathway, during REM sleep selectively disrupted social memory while sparing contextual fear memory. This functional dissection establishes a hypothalamo-septo-hippocampal circuit (lateral SuM-MS-CA2) dedicated to social memory processing, in parallel to the recently-described direct SuM-CA2 pathway. These results also position the SuM as a REM sleep-hub that routes information via parallel septal pathways to consolidate distinct memory modalities.

neuroscience↗

bioRxiv2026

Coordinated inhibition of SOX9 and cell cycle progression by microRNA-200 restricts sebaceous gland fate specification

The microRNA-200 family (miR-200s) is widely recognized for their potent role in inhibiting epithelial-to-mesenchymal transition and cell cycle progression in cancer. However, their functional specificity in normal epithelial development remains poorly understood. Here we show that miR-200s are highly enriched in hair matrix progenitors but conspicuously absent from the upper hair follicle (HF), the anatomical location where sebaceous gland (SG) and HF stem cells are specified. We demonstrate that elevated miR-200 expression in this region abolishes SG fate specification while permitting hair morphogenesis. Genome-wide identification of miR-200 targets reveals that miR-200s regulate multiple negative regulators of WNT signaling, in addition to cell cycle regulators. Single-cell and spatial transcriptomic analyses uncover a mutually exclusive expression patterns between WNT activity and SOX9 in the upper HF, which is disrupted by miR-200 induction, resulting in compromised SOX9 function. Mechanistically, genome-wide identification of SOX9 targets uncovers a broad network of lipid and fatty acid metabolism genes critical for the transition of upper HF progenitors to the SG fate. The coordinated inhibition of the SOX9-dependent lipogenic program and the potent restriction of cell cycle progression, both mediated by miR-200s, collectively blocks SG specification. Taken together, this work reveals an unexpected specificity of miR-200 in restricting epithelial plasticity and elucidates a spatially defined SOX9 regulatory network essential for SG development.

developmental biology↗

bioRxiv2026

Mitochondrial dsRNA: A Hidden Source of Immunogenic RNA in ADAR1 Deficiency

Double-stranded RNA (dsRNA) triggers immune responses during viral infections, but self-derived dsRNA can activate similar pathways. To prevent this, the body relies on mechanisms like ADAR1, an RNA-editing enzyme essential for immune regulation. Dysfunction of ADAR1 is linked to various diseases, yet the nature and role of dsRNAs accumulating in its absence remain unclear. Here, we identify mitochondrial dsRNA (mt-dsRNA), transcribed from the mitochondrial genome, as a major contributor to the endogenous dsRNA pool in ADAR1-deficient human and murine cells. We propose a "Draw-and-Release" model, where ADAR1 loss increases mitochondrial reactive oxygen species (mtROS), causing mt-dsRNA accumulation in the mitochondrial matrix ("Draw" phase) and its immune-activating release into the cytosol upon mitochondrial protein dysfunction ("Release" phase). This study highlights the importance of mitochondrial integrity in mitigating ADAR1-related pathologies.

cell biology↗

bioRxiv2026

Periplasmic gatekeeping of phage DNA entry by rSAM enzyme-mediated maturation of an effector with His-X-Ser repeats

In the relentless arms race between bacteria and phages, bacteria have evolved a variety of defense strategies to combat phage infection. However, no bacterial system has been identified that specifically target the phage DNA entry phase. Here, we present a novel bacterial antiphage system, termed HXS, which provides broad-spectrum and robust antiphage activity by interfering with phage DNA entry. The HXS system consists of two radical S-adenosylmethionine (rSAM) enzymes (HxsB and HxsC), a small protein (HxsD), and the effector HxsA with a peptidoglycan-binding domain and five His-Xaa-Ser (HXS) repeats. HxsB/HxsC catalyze rSAM enzyme-dependent maturation of HxsA, including N-terminal processing and a site-specific +8 Da modification, thereby producing a periplasmic effector required for HXS defense. Biochemical evidence supports a model in which the matured effector likely engages incoming DNA electrostatically to arrest entry, establishing an rSAM enzyme-modified protein effector in antiphage defense.

microbiology↗

bioRxiv2025

Automated, modular assembly of reconstituted cell-free systems from in vitro-produced components

High-performance cell-free protein synthesis has transformative potential for synthetic biology, yet the prohibitive costs of PURE kits and the labor intensity of in-house preparation have restricted accessibility and scalability. We developed i-POPFLEX (Purified components OPtimized for FLEXible protein expression), a modular cell-free protein synthesis system in which 34 translation factors, individually synthesized in vitro, are assembled using automated liquid handling. This workflow minimizes manual input and supports parallelized production, generating complete, ready-to-use systems within two days. i-POPFLEX achieves up to 5-fold higher protein yields and a 95 % cost reduction (20-fold lower cost) compared with commercial kits. Its flexible architecture also enables selective component inclusion for genetic code reprogramming and site-specific incorporation of non-canonical amino acids. By coupling modular design with automation, i-POPFLEX provides an accessible, customizable, and economically viable platform for next-generation biomanufacturing workflows. Technology readinessi-POPFLEX is a reconstituted cell-free system (CFS) composed of 34 translational components that are individually synthesized in vitro and assembled by automation. This system achieves up to 5-fold higher protein yields with a 95 % cost reduction (20-fold lower; <USD 0.06 {micro}L-1) compared with commercial PURE kits (USD 1.36 {micro}L-1) and reduces preparation time from four days to two. The workflow has been validated across diverse protein and peptide synthesis applications, including genetic code reprogramming and site-specific incorporation of non-canonical amino acids, and integrates seamlessly with benchtop automated liquid-handling platforms. These capabilities place i-POPFLEX at Technology Readiness Level (TRL) 4-5: integrated components validated in a laboratory setting and advancing toward pilot-scale readiness. For full-scale deployment, several key challenges remain. Matching crude lysate costs (USD 0.03 {micro}L-1) will require bulk reagent production, optimized procurement strategies, and specialized equipment for high-throughput component synthesis. Enabling milliliter- and liter-scale production will demand improvements in upstream synthesis, downstream purification, and quality control to ensure consistent performance at industrial throughput. Overcoming these barriers would enable production of thousands to millions of fully assembled i-POPFLEX systems for biofoundry-scale enzyme engineering, metabolic pathway prototyping, and large-scale variant screening, democratizing reconstituted CFS technology, and accelerating adoption in next-generation biomanufacturing pipelines.

synthetic biology↗

bioRxiv2025

Efficient Generation of Humanized Cloned Cattle via Embryonic Stem Cell-Mediated Dual-Round Site-Specific Editing

Transgenic cloning allows genetic modification in cattle, yet its translational potential is constrained by low cloning efficiency and limited gene-editing capacity, due largely to the restricted proliferative ability of somatic donor cells. Pluripotent stem cells (PSCs), with their unlimited self-renewal ability, represent a promising alternative to overcome these bottlenecks. Here, we first established stable bovine epiblast stem cell lines (bEpiSCs) and achieved site-specific integration of the HCSN2-HLF-GFP cassette into the {beta}-casein locus, with high transfection (72.07%) and correct integration efficiency (80.48%). Following Cre LoxP mediated excision of the selectable marker, we obtained marker free HCSN2-HLF bEpiSCs that retained pluripotency markers, tri lineage differentiation potential, and supported target protein expression in immortalized bovine mammary epithelial cells. When used as nuclear donors, these cells produced blastocysts with quality comparable to in vitro fertilization (IVF) embryos. Notably, cloning with HCSN2-HLF bEpiSCs resulted in the birth of twelve calves, with significantly higher birth and survival rates (30.71% and 16.74%, respectively) than those obtained using fibroblasts. Both PCR-based genotyping of the edited loci and microsatellite kinship analysis confirmed that all cloned calves were genetically derived from the HCSN2-HLF bEpiSCs. Collectively, this study establishes an efficient embryonic stem cell based platform for targeted gene editing and rapid production of multigene edited cloned cattle, offering a scalable strategy with strong potential for industrial translation.

bioengineering↗

bioRxiv2025

Naturally occurring mutations in replication proteins of a small RNA virus that alter the number, sizes, and relative abundances of subgenomic RNAs

Many positive-strand (+) RNA viruses produce subgenomic RNAs (sgRNAs) in infected cells. sgRNAs are synthesized by virus-encoded replication proteins (RPs), but whether RPs regulate the number and sizes of sgRNAs remains largely unknown. We report multiple naturally occurring mutations within the RPs of turnip crinkle virus (TCV) that alter the number, sizes, and relative abundances of TCV sgRNAs. TCV is a (+) RNA virus that normally produces two sgRNAs: the 1,724-nucleotide (nt) sgRNA1 expressing movement proteins, and the 1,449-nt sgRNA2 expressing capsid protein. A single amino acid change, A113V, within a region shared by TCV RPs p28 and p88, diminished sgRNA1 levels and delayed viral systemic spread. Interestingly, three second-site RP mutations emerged in infected plants that, alone or in combination with A113V, resulted in over-production of sgRNA1 or accumulation of two alternative sgRNAs of 1,876 and 1,601 nt, and rescued A113V defects. The alternative sgRNAs originated from nearly identical recombination events, their size difference reflecting varying 5 extensions. Structural modeling of the TCV replication complex showed a conical ring architecture containing p28, p88, and a partially double-stranded RNA. While A113 may interact with TCV genomic RNA or host factors to promote (-) sgRNA1 synthesis, the second-site mutations likely influenced binding and entry of RNA template into the p88 active site. They may stall RNA synthesis at specific hotspots and stimulate template switching, thereby generating alternative (-) sgRNAs. Our findings reveal previously unrecognized constraints on viral RPs that ensure production of sgRNAs with precise sizes and abundances. Author summaryMany (+)-strand viruses, such as SARS-CoV-1 and -2, Chikungunya virus, and tomato mosaic virus, synthesize subgenomic RNAs (sgRNAs) during cellular infections. Targeting sgRNA production could prove to be an effective antiviral strategy, as sgRNAs are needed to express diverse proteins critical for viral survival and transmission. Although sgRNA production requires virus-encoded replication proteins (RPs), whether RPs also dictate the number, sizes, and relative abundances of viral sgRNAs remain to be thoroughly investigated. We identified and characterized four naturally occurring mutations in RPs of the plant-infecting turnip crinkle virus that specifically perturbed one of the sgRNAs. Our findings uncover novel constraints on viral RPs that safeguard sgRNA integrity, and avail them as potential targets for controlling pathogenic viruses.

plant biology↗

bioRxiv2025

Tibetan near-complete pangenome reveals complex variants underlying high-altitude adaptation

Genomic diversity in indigenous populations offers critical insights into human evolution and population-specific adaptation. Here, we generated 70 near-complete, fully phased genome assemblies from 35 high-altitude Tibetan trios and identified 4.55 million small variants and 63,031 structural variants (SVs) absent from the current global pangenome reference. Comparative analyses with a 595 globally diverse long-read genome dataset revealed 207 previously uncharacterized Tibetan-enriched SVs spanning 275 genes implicated in high-altitude physiological adaptation. Genotyping these SVs in 1,164 Tibetan and Han individuals with 88 physiological traits reveals five variants significantly associated with cardiopulmonary and hematological phenotypes central to hypoxia adaptation. We further map 2.45 Gb of archaic hominin sequences in Tibetans and uncover 18 previously unrecognized introgressed regions enriched in Tibetans with genes related to hematopoiesis and lung function. These regions harbor five Tibetan-enriched SVs, indicating that archaic introgression contributed SVs relevant to human adaptation. Together, these findings reveal substantial uncharacterized genomic diversity in Tibetans and highlight a previously underappreciated role of SVs and archaic SVs in shaping human evolution and high-altitude adaptation.

genomics↗

bioRxiv2025

Integrative Analysis of Spatial Transcriptome and Connectome by SpaCon

The brains structure and function arise from its complex molecular composition and neural connectivity, yet the relationship between cell-type-specific gene expression and brain-wide connectivity is not well understood. By integrating single-cell resolution spatial transcriptomics and connectomics, we reveal tight gene-connectivity coupling in the cortico-thalamic circuit. To uncover the latent factors associating connectivity with gene expression, we focused on the often-overlooked extrasomatic mRNAs in spatial transcriptomics and identified specific gene expression in axons of the corpus callosum that reflect their cortical origins. Building on these findings, we developed SpaCon, a deep-learning method that flexibly integrates global connectivity with local gene expression. SpaCon employs efficient neighbor-sampling to enable whole-brain analysis while preserving performance. This architecture allows the model to identify functionally relevant three-dimensional domains defined by transcriptome-connectome patterns, even when spatially distant. Validated across diverse datasets and species, SpaCon significantly enhances the prediction of connectivity from gene expression and improves the spatial classification of neuronal subtypes. SpaCon provides a powerful, scalable, and versatile framework for understanding transcriptome-connectome relationships.

neuroscience↗

bioRxiv2025

Reliable delineation of Clostridioides difficile and related members of the family Peptostreptococcaceae using phylogenomics and spore coat protein-specific molecular markers

Traditional bacterial classification relies on phenotypic traits (e.g., morphology, metabolic profiles), but these methods lack resolution for closely related taxa and are biased by culture conditions. While 16S rRNA gene sequencing is a widely used molecular complement, it fails to resolve closely related Peptostreptococcaceae species, including Clostridioides difficile. These limitations have caused family-level taxonomic confusion and ambiguous Clostridioides genus boundaries, hindering clinical identification of pathogenic strains and posing public health risks. To address these limitations, we developed an integrated approach combining multi-scale phylogenomic and protein-based molecular evidence, adopting a hierarchical workflow: first, constructing a 16S rRNA phylogeny of 151 Firmicutes strains to demonstrate traditional marker inadequacies; second, generating a whole-genome protein phylogeny of 51 representative Peptostreptococcaceae genomes and defining taxonomic boundaries via Average Amino Acid Identity (AAI); third, analyzing spore-associated protein patterns across C. difficile isolates and related genomes. Results revealed high conservation of C. difficile spore coat/exosporium proteins and clear genus-level phylogenetic distinctiveness of these proteins. Combined with AAI-validated whole-genome data, our findings support key Peptostreptococcaceae taxonomic revisions: redefining polyphyletic Romboutsia, reassigning Eubacterium tenue to Paeniclostridium, and elevating Alkalithermobacter to genus status. This study establishes spore coat proteins as core taxonomic markers for spore-forming bacteria, with our integrated strategy overcoming traditional limitations to improve classification accuracy and C. difficile surveillance. ImportanceConventional classification struggles to resolve closely related Peptostreptococcaceae species (e.g., C. difficile). We developed an integrated framework combining 16S rRNA sequencing, whole-genome protein analysis, and spore trait assessment, with a key innovation: identifying spore coat/exosporium proteins as robust, conserved taxonomic markers. This approach enabled three pivotal Peptostreptococcaceae revisions--redefining Romboutsia, reassigning Eubacterium tenue to Paeniclostridium, and elevating Alkalithermobacter to genus rank. The findings resolve a longstanding microbial systematics bottleneck for spore-forming bacteria, provide critical taxonomic context for C. difficiles precise monitoring and prevention, and expand taxonomic markers beyond nucleic acid-based methods. This advances classification precision, critical for microbial ecology, pathogenesis, and industrial microbiology research.

genomics↗

bioRxiv2025

Single-cell transcriptomic dynamics exposes hidden survival trajectory under antibiotic treatment

Heterogeneity plays a major role in bacterial resistance to antibiotic treatment while the mechanism at single-cell level is largely unknown. Here, we employed a robust integration of bulk and bacterial single-cell RNA-seq (scRNA-seq) to uncover how individual cells of Acinetobacter baumannii reorganise the heterogenous transcriptome in response to antibiotic. Using polymyxin as a representative, bulk RNA-seq showed canonical envelope- and efflux-centred responses but obscured underlying heterogeneity. Single-cell profiling resolved these averages into discrete subpopulations whose abundances shifted with concentration and time. Specifically, in early time an envelope-stress programme predominated survival at the low concentration, whereas an outer-membrane repair/efflux programme dominated survival at the high concentration. These patterns revealed structured and time-resolved heterogeneity, highlighting an ingenious bacterial stress responsive strategy. Through trajectory inference, we further revealed a concentration-dependent bifurcation of cell fates: low-concentration treated cells detoured through a transient stress state and rejoined growth, whereas high-concentration treated survivors diverted into a slow-growing, tolerant branch. Perturbing marker genes from these programmes altered fitness eventually and rapidly increased permeability, depolarisation and reactive-oxygen burden, linking state to survival capability. Collectively, we map a dynamic, concentration-structured landscape of antibiotic responses at the single-cell level, revealing diverse survival trajectories that are obscured in conventional population-averaged analyses. Our developed single-cell based framework revealed tolerant bacterial cells with rewiring of the transcriptional landscape, causing emergence of antibiotic resistance. Importantly, these findings urge precision antimicrobial therapy in patients to minimise emergence of antibiotic resistance.

microbiology↗

bioRxiv2025

MAGIC: Methylation Analysis with Genomic Inferred Contexts

MotivationWhole-genome bisulfite sequencing (WGBS) enables base-resolution methylation profiling but poses statistical challenges for differential methylation analysis. While existing methods have made important progress using uniform dispersion shrinkage across CpGs, there remains opportunity to better capture methylation heterogeneity across the genome. There is a need to account for context-specific methylation variability and to improve detection accuracy under realistic sequencing constraints. ResultsWe propose MAGIC (Methylation Analysis with Genomic Inferred Contexts), a beta-binomial mixture model that learns genomic contexts directly from methylation data. MAGIC models genomic heterogeneity through context-specific dispersion shrinkage and detects differential methylation via two complementary tests, including a Wald test and Bayes factor test. Simulations across various coverage and effect sizes demonstrate that MAGIC improves sensitivity and false-positive rate compared with DSS, providing a robust framework for differential methylation analysis in WGBS data. AvailabilityThe source code of MAGIC is available at https://github.com/Pickledzebra/MAGIC. ContactMatteoP@mcdb.ucla.edu Supplementary informationSupplementary data are available at bioRxiv.

bioinformatics↗

bioRxiv2025

Delivery of collagen-encoding mRNA to the skin for cosmetic applications

Collagens, the predominant structural proteins in mammalian, maintain tissue integrity through its unique triple-helical conformation. Traditionally, cosmetic collagens have been administered as hydrolyzed peptides derived from animal sources, which exhibit poor bioavailability and functional efficacy due to limited skin penetration and disrupted tertiary/quaternary structures. To overcome these limitations, we developed a novel system for in vivo collagen expression. This system utilizes the topical application of in vitro synthesized, AI-designed mRNAs encoding types I, III, and XVII collagens to improve human skin condition. Significant upregulation of target collagen expression was observed in dermal fibroblasts, leading to improved skin condition through in situ assembly of collagens in natural conformation.

bioengineering↗

bioRxiv2025

Adipocytes are dispensable in shaping the ovarian cancer tumor microenvironment in the omentum

The omentum, a specialized adipose tissue within the peritoneum, is a primary niche for ovarian cancer (OC) dissemination during peritoneal carcinomatosis. Traditionally, omental adipocytes are thought to promote OC growth by supplying lipids, supported by evidence that global FABP4 deficiency reduces tumor progression. Here, we generated mice lacking mature adipocytes in the peritoneum, including the omentum. ID8p53-/-Brca2-/-, BPPNM, and KPCA OC cells retained a propensity to seed regions typically associated with adipocytes, even without mature adipocytes. However, the lack of mature adipocytes did not suppress peritoneal OC expansion, whereas removing the adipocyte-free omentum did. Murine and human single-cell RNA sequencing revealed that endothelial FABP4 was high in the omentum. Indeed, endothelial cell-selective deficiency of FABP4 reduced OC growth in the peritoneum. These findings prompt a reevaluation of adipocyte contributions to OC progression and suggest a key role of the omental vasculature in supporting OC metabolic growth.

cancer biology↗

bioRxiv2025

A Cross-scale Causal Mapping Framework Pinpoints Macrophage Orchestrators of Balanced Arterial Development

Postnatal pulmonary arteries experience an abrupt surge in flow that demands tightly coordinated remodeling of vascular structure and mechanical compliance. However, the cellular programs orchestrating these multiscale adaptation remain poorly defined, partly due to the absence of analytical tools integrating gene-cell-tissue scales. Here, we present CausaLink, a cross-scale causal mapping framework that predicts how altered gene expression propagates through gene-cell-tissue networks by integrating time-course transcriptomic and tissue morpho-mechanical data. We constructed a single-cell transcriptomic atlas of 11,143 proximal pulmonary artery-derived cells from C57BL/6J mice across five developmental stages (P2, P10, P21, P42, and P84), revealing dynamic lineage transitions and transient mesenchymal population specifying into fibroblasts and smooth muscle cells from P2 to P21. Using this framework, we identified Mgl2 macrophages as central regulators promoting lumen expansion while preventing pathological wall thinning or thickening. To validate these predictions, we established a human induced pluripotent stem cell-derived arterial assembloid enriched in MGLhigh macrophages. In this model, MGLhigh macrophages supported lumen enlargement while maintaining overall wall thickness and induced formation of an adventitia-like fibroblast layer that recapitulated approximately 80% of the native adventitial fraction with balanced collagen-elastin remodeling. By linking predictive modeling to human organoid validation, this study establishes a cross-scale workflow for tracing how gene programs shape vascular architecture, offering mechanistic insights and a foundation for predictive regenerative medicine.

bioengineering↗

bioRxiv2025

Myelin pathology is a key feature of X-linked Dystonia Parkinsonism

X-linked Dystonia-Parkinsonism (XDP) is a progressive, adult-onset neurodegenerative movement disorder that predominantly affects males of Filipino descent1-3. The disease is caused by the insertion of a SINE-VNTR-Alu subfamily F (SVA_F) retrotransposon within an intron of the TATA-box binding protein-associated factor 1 (TAF1) gene4. A major barrier to understanding the pathophysiology of XDP has been the lack of relevant animal models. Here, we introduce a novel conditional humanized XDP mouse model harboring a hybrid mouse-human Taf1/TAF1 gene (hyTAF1) containing the pathogenic SVA_F insertion. We activated the hyTAF1 in Nestin+ neural progenitor cells and found that the resulting XDP male mice recapitulate features of the human disease including severe motor impairment, striatal atrophy, and reactive gliosis. Transcriptomic, histological, and electron microscopy analysis revealed a dramatic reduction in oligodendrocyte lineage cells and widespread myelin disruption. Consistent with these findings, postmortem brain tissue from XDP patients revealed similar myelin pathology, including near-complete loss of myelin in parts of the medial prefrontal cortex. Together, these results identify oligodendrocyte dysfunction and myelin loss as previously unrecognized contributors to XDP pathogenesis, providing new mechanistic insight into this debilitating disorder.

neuroscience↗

bioRxiv2025

Simultaneous Label-free Imaging of Nucleolar Dynamics and Subcellular Metabolic Shifts Across Tissue Contexts

The nucleolus is essential for ribosome biogenesis and for regulating cellular responses to growth and stress, and its relationship to cellular metabolic activity and functional state highlights its potential as a biomarker of cellular health. However, challenges in contrast multiplexing and high-resolution isotropic three-dimensional (3D) imaging hinder the non-invasive, simultaneous assessment of nucleolar activity and subcellular metabolic maps across different tissue contexts, especially in complex 3D environments. To fully harness the nucleoluss potential as a biomarker and diagnostic target, we present a multimodal imaging platform that combines third harmonic generation (THG) imaging with metabolic autofluorescence of NAD(P)H and FAD to study structural and metabolic nucleolar dynamics. Enabled by a high-power multimode fiber source and an axial deblurring network, we achieved [~] 400 nm isotropic resolution in deep 3D imaging and confirmed the high accuracy of our method for label-free nucleolus identification using co-registered immunostaining and electron microscopy. To establish the biological relevance of our approach, we demonstrate that nucleolar stress leads to an unexpected depletion of NADH across cellular compartments. Furthermore, in the human endometrium--where nucleolar dynamics are central to the tissues response to progesterone--our label-free imaging strategy delineated endometrial structures in freshly excised tissues and revealed that progesterone treatment induces distinct changes in nucleolar translocation and metabolic adaptation in organoids derived from diseased patients compared to controls. This capacity to non-invasively visualize and quantify features of the nucleolus and its local metabolic microenvironment at single-cell resolution in human tissues--and dynamically track these changes over time in patient-derived organoids--provides a powerful tool for uncovering the roles of the nucleolus in development, disease progression, and therapeutic response. Together, these findings establish our platform as a significant advance for both fundamental research and organelle-based tissue diagnostics.

cell biology↗

bioRxiv2025

In Vivo Metabolic Tagging and Targeting of Circulating Red Blood Cells

Engineering red blood cells (RBCs) has been widely explored for drug delivery, imaging, vaccination, and other applications. However, effective strategies to directly engineer RBCs in vivo still do not exist. Here, for the first time, we report successful metabolic glycan labeling of RBCs in vivo. We demonstrate that systemically administered azido-sugars can metabolically label circulating RBCs with azido groups in the form of glycoproteins and glycolipids, with contributions from the labeling of both mature RBCs in the bloodstream and RBC precursor cells in the bone marrow. The RBC labeling efficiency can be improved by optimizing the choice and dose and dosing frequency of azido-sugars. The surface azido tags on RBCs can persist for >42 days in mice (nearly the lifespan of mouse RBCs), in sharp contrast to azido tags on leukocytes in the blood and cells in healthy tissues that decay to undetectable levels within 3 days. This in vivo RBC labeling technology does not induce any noticeable toxicity to RBCs, leukocytes, and healthy tissues. We further demonstrate that azido-labeled RBCs can covalently capture dibenzocyclooctyne-bearing cargos in vivo via click chemistry, prolonging the blood circulation of cargos from typical hours to >35 days. In a few examples, we show that the unprecedented RBC tagging and targeting technology can improve the fluorescence imaging of blood vessels and tumor tissues, enable long-term magnetic resonance imaging of brain vasculatures with one dose of gadolinium agent, and enhance the pharmacokinetics of drugs such as insulin.

bioengineering↗