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Kang, J.

Publications and source records attributed to Kang, J..

At least 55 records · Page 3Linked to original sources

Local optogenetic control of genome editing and tumorigenesis in vivo using wireless implantable optoelectronics

Precise spatial regulation of site-specific DNA recombination (SSR) in vivo remains a challenge due to limited tunability of current platforms. Here, we present an optogenetic approach that overcome these limitations by employing engineered light-regulated recombinase E-LightR-Cre and tunable wireless implantable optoelectronic devices. E-LightR-Cre meets the key criteria for spatial regulation of SSR in vivo, showing no detectable activity in the dark, while demonstrating robust activation upon blue-light illumination. To achieve local E-LightR-Cre activation in murine lungs, we developed wireless, fully-implantable optoelectronic devices enabling focal illumination with no discernible organ damage. By modulating illumination intensity and duration, we can control the size of the activated area. Local expression of oncogenic KRas-G12D in a photoactivated subpopulation of cells in vitro revealed rapid reprogramming of the mutant expressing cells and their non-activated neighbors. Light-guided activation of E-LightR-Cre in mouse lungs resulted in focal expression of a reporter gene and allowed us to induce local formation of oncogenic lesions in vivo.

bioengineering↗

CTCF-binding sites demarcate chromatin domains enriched with H3K9me2 or H3K9me3 and restrict the spreading of these histone modifications in human cells

CTCF-binding sites are frequently found at the boundaries of chromatin domains enriched with specific histone modifications in vertebrate genomes, where they function as barriers that limit the spreading of these modifications. However, their role in domains marked by H3K9me2 or H3K9me3 remains poorly understood. In this study, we analyzed CTCF-binding sites and the distribution of H3K9me2 and H3K9me3 around them in human K562 cells, and investigated the spreading of these modifications following CTCF depletion. Genome-wide analysis revealed that certain CTCF-binding sites are located at the boundaries of chromatin domains enriched with H3K9me2 or H3K9me3. Upon loss of CTCF binding, both modifications spread to neighboring chromatin at over half of the boundaries delimiting highly and distinctly enriched domains. Boundaries where such spreading did not occur were flanked by chromatin in a more active state compared to those where spreading occurred. Gene transcription was significantly reduced in neighboring regions where H3K9me2 or H3K9me3 had spread. Further comprehensive analysis revealed that this transcriptional reduction was specifically associated with the spread of H3K9me2. These findings suggest that CTCF-binding sites demarcate chromatin domains enriched with H3K9me2 or H3K9me3 and act as barriers to restrict the spread of these modifications in mammalian cells. Notably, the spread of H3K9me2 appears to play a specific role in transcriptional repression.

molecular biology↗

Contrastive Representation Learning for Single Cell Phenotyping in Whole Slide Imaging of Enrichment-free Liquid Biopsy

Tumor-associated cells derived from a liquid biopsy are promising biomarkers for cancer detection, diagnosis, prognosis, and monitoring. However, their rarity, heterogeneity and plasticity make precise identification and biological characterization challenging for clinical utility. Enrichment-free approaches using whole slide imaging of all circulating cells offer a comprehensive and unbiased strategy for capturing the full spectrum of tumor-associated cell phenotypes. However, current analysis methods often depend on engineered features and manual expert review, making them sensitive to technical variations and subjective biases. These limitations highlight the need for a better feature representation to improve performance and reproducibility of applications in large-scale patient cohort analyses. In this study, we present a deep contrastive learning framework for learning features of all circulating cells, enabling robust identification and stratification of single cells in whole slide immunofluorescence microscopy images. We demonstrate performance of learned features in classification of diverse cell phenotypes in the liquid biopsy, achieving an accuracy of 92.64%. We further demonstrate that learned features improve performance in downstream applications such as outlier detection and clustering. Lastly, our feature representation enables automated identification and enumeration of distinct rare cell phenotypes, achieving average F1-score of 0.93 across cell lines mimicking circulating tumor cells and endothelial cells in contrived samples and average F1-score of 0.858 across CTC phenotypes in clinical samples. This workflow has significant implications for scalable analysis of tumor-associated cellular biomarkers in clinical prognosis and personalized treatment strategies.

cancer biology↗

Spatially varying graph estimation for spatial transcriptomics cancer data

Modern spatial transcriptomic profiling techniques facilitate spatially resolved, high-dimensional assessment of cellular gene transcription across the tumor domain. The characterization of spatially varying gene networks enables the discovery of heterogeneous regulatory patterns and biological mechanisms underlying cancer etiology. We propose a spatial Graphical Regression (sGR) model to infer spatially varying graphs for high-resolution multivariate spatial data. Unlike existing graphical models, sGR explicitly incorporates spatial information to infer non-linear conditional dependencies through Gaussian processes. It conducts sparse estimation and selection of spatially varying edges, at both spatial and sub-spatial levels. Extensive simulation studies illustrate the profitability of sGR for spatial graph structural recovery and estimation accuracy. Our methods are motivated by and applied to two spatial transcriptomics data sets in breast and prostate cancer, to investigate spatially varying gene connectivity patterns across the tumor micro-environment. Our findings reveal several novel spatial interactions between genes related to immune activation and carcinogenesis regulation such as CD19 in breast cancer and ARHGAP family in prostate cancer. We also provide a modular software package for fitting and visualization of spatially varying graphs.

genomics↗

ArcDFI: Attention Regularization guided by CYP450 Interactions for Predicting Drug-Food Interactions

CYP450 isoenzymes are known to be deeply involved in the formation of drug-food interactions (DFI). Previously introduced computational approaches for predicting DFIs do not take drug-CYP450 interactions (DCI) into account and have limited generalizability in handling compounds unseen during model training. We introduce ArcDFI, a model that utilizes attention regularization guided by CYP450 interactions to predict drug-food interactions. Experimental results demonstrate ArcDFIs ability to predict DFIs when given unseen food or drug compounds as input. Analysis of its attention mechanism provides insight into its current understanding of DCI and how they are related to its DFI predictions. To the best of our knowledge, ArcDFI is the first DFI prediction model that incorporates the concept of DCI, resulting in improved predictive generalizability and model explainability. ArcDFI is available at https://github.com/KU-MedAI/ArcDFI

pharmacology and toxicology↗

Loudness and sound category: Their distinct roles in shaping perceptual and physiological responses to soundscapes

When compared to nature sounds, exposure to mechanical sounds evokes higher levels of perceptual and physiological arousal, prompting the recruitment of attentional and physiological resources to elicit adaptive responses. However, it is unclear whether these attributes are solely related to the sound intensity of mechanical sounds, since in most real-world scenarios, mechanical sounds are present at high intensities, or if other acoustic or semantic factors are also at play. We measured the Skin Conductance Response (SCR), reflecting sympathetic nervous system (SNS) activity as well as the pleasantness and eventfulness of the soundscape across two passive and active listening tasks in (N = 25) healthy subjects. The auditory stimuli were divided into two categories, nature, and mechanical sounds, and were manipulated to vary in three perceived loudness levels. As expected, we found that the sound category influenced perceived soundscape pleasantness and eventfulness. SCR was analysed by taking the mean level across the stimulus epoch, and also by quantifying its dynamic. We found that mean SCR was modulated by loudness only. SCR rise-time (a measure of speed of the skin response) correlated significantly with soundscape pleasantness and eventfulness for nature and mechanical sounds. This study highlights the importance of considering both loudness level and sound category in evaluating the perceptual soundscape, highlighting SCR as a valuable tool for such assessments. Impact statementLoud mechanical sounds are considered more unpleasant than nature sounds. This study examined whether loudness alone causes this effect or if the type of sound (e.g., mechanical vs. Nature) also plays a role. By measuring skin conductance reflecting the automatic and unconscious activation of the bodys autonomic system, we found that physical reactions are driven by loudness but also correlate with the listeners judgement of the pleasantness and eventfulness (describing the perceived level of activity or stimulation) of a soundscape.

neuroscience↗

In vivo self-renewal and expansion of quiescent stem cells from a non-human primate

The development of non-human primate models is essential for the fields of developmental and regenerative biology because those models will more closely approximate human biology than do murine models. Based on single cell RNAseq and fluorescence-activated cell sorting, we report the identification and functional characterization of two quiescent stem cell populations (skeletal muscle stem cells (MuSCs) and mesenchymal stem cells termed fibro-adipogenic progenitors (FAPs)) in the non-human primate Microcebus murinus (the gray mouse lemur). We demonstrate in vivo proliferation, differentiation, and self-renewal of both MuSCs and FAPs. By combining cell phenotyping with cross-species molecular profiling and pharmacological interventions, we show that mouse lemur MuSCs and FAPs are more similar to human than to mouse counterparts. We identify unexpected gene targets involved in regulating primate MuSC proliferation and primate FAP adipogenic differentiation. Moreover, we find that the cellular composition of mouse lemur muscle better models human muscle than does macaque (Macaca fascicularis) muscle. Finally, we note that our approach presents as a generalizable pipeline for the identification, isolation, and characterization of stem cell populations in new animal models.

cell biology↗

MF-PENS: An Efficient and Versatile Nuclear Extraction Method for Plant Single-Cell Sequencing

The widespread adoption of single-cell transcriptomics in plants remains constrained by the challenges of isolating high-quality nuclei from tissues with rigid cell walls and complex metabolomes. Here, we present methanol fixation and Percoll-enriched nuclei sorting (MF-PENS), a robust strategy designed to tackle these limitations. Distinct from conventional protocols, MF-PENS circumvents the need for fluorescence activated cell sorting (FACS) and effectively reduce RNA leakage, consistently yielding high-quality single-nucleus RNA sequencing (snRNA-seq) data. MF-PENS has been validated across various plant tissues, including fresh and frozen rice roots and leaves, as well as recalcitrant samples such as soybean root nodules, soybean seeds, and tomato fruits. Benchmarking results demonstrate that MF-PENS significantly enhances gene capture efficiency, cell clustering performance, and cell type annotation accuracy. With its broad applicability and superior performance, MF-PENS represents a robust and versatile tool for plant single-cell research, facilitating deeper insights into plant development and biology processes.

plant biology↗

Characterization of the gut mycobiome in patients with non-alcoholic fatty liver disease and correlations with serum metabolome

BackgroundThe relationship between the gut mycobiome and non-alcoholic fatty liver disease (NAFLD) is largely unexplored. MethodsIn this study, we used a publicly available shotgun metagenomic sequencing dataset of fecal samples to compare the gut fungal communities of 90 NAFLD patients with those of 90 healthy controls. We examined their correlations with gut bacterial communities, host serum metabolite s, and the interactions of key taxa within these networks. ResultsOur results revealed a remarked dysbiosis in the gut mycobiome of NAFLD patients, cha racterized by a significant increase in four fungal taxa, including Pseudopithomyces sp. c174, Muc or sp. c176, Aspergillus sp. c25, and uncultured Ascochyta c213. Multi-omics analysis showed that the gut mycobiome significantly contributes to the host serum metabolome. Pseudopithomyces s p. c174 was notably associated with some beneficial blood metabolites, such as glycoursodeoxycholic acid and alpha-linolenic acid, whereas the NAFLD-enriched pro-inflammatory phenylacetic acid was linked to Aureobasidium sp. c170 and Basipetospora sp. c193. Network analysis revealed significant alterations in the gut microbiome of NAFLD patients, highlighting the potential roles of Alternaria alternata c42, Penicillium sp. c5, and uncultured Malassezia c303. Moreover, predictive models that integrated both bacterial and fungal taxa improved prediction accuracy, emphasizing the crucial role of gut fungi in NAFLD. ImportanceNon-alcoholic fatty liver disease (NAFLD) is a widespread liver condition with limited treatments. While gut bacteria have been extensively studied in NAFLD, the role of gut fungi (the mycobiome) remains poorly understood. This study fills that gap by characterizing gut fungal communities in NAFLD patients and linking these changes to their blood metabolite profiles. We found that NAFLD patients show distinct fungal imbalances, which correlate with key metabolic alterations in the host. These findings expand our understanding of NAFLD by spotlighting gut fungi as important contributors to disease progression. This insight opens new avenues for potential biomarkers and therapies targeting the gut-liver axis. ConclusionsOur findings provide a comprehensive understanding of the link between the gut mycobiome and NAFLD progression, which is essential for guiding future therapeutic research.

microbiology↗

Development of an image-guided non-vitrectomy subretinal access approach for trans-scleral cell and gene therapy delivery

PurposeRegenerative therapies for retinal diseases include cell and gene therapy modalities that are targeted to the subretinal space. Several recent clinical trials have shown that the morbidity of surgical access is the major limitation of safe subretinal space delivery. We aimed to develop an image-guided procedure for minimally invasive subretinal access (MISA) as a platform to deliver therapeutic agents for the treatment of degenerative retinal diseases. MethodsWe engineered prototypes of a novel common-path swept source optical coherence tomography (CP-SSOCT)-enabled needle, coaxial guide (COG), and subretinal access cannula (SAC). We pilot tested the MISA procedure in ex vivo bovine eyes and in vivo porcine ocular surgery. ResultsA- and M-mode scan recordings of ex vivo and in vivo animal eye models demonstrated that CP-SSOCT imaging from the scleral side (ab externo) was capable of identifying the retinal laminae and the sub-retinal space. We show results from in vivo porcine MISA surgeries (N=4) using the novel CP-SSOCT-enabled sub-retinal injection needle, COG, and SAC through the transscleral approach. The MISA approach enabled subretinal device placement in the posterior pole, however, cases of retinal incarceration and retinal perforation were encountered. ConclusionsWe describe a novel CP-SSOCT-guided subretinal access approach that, with further optimization, may be useful in regenerative retinal surgery.

bioengineering↗

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↗

IQI: Individualized Quantitative trait loci (QTL) Index

There is currently no standard efficient method to precisely detecting and characterizing the difference of quantitative trait loci (QTL) effect among groups and/or populations at individual level. The main reason is that the traditional global regression based QTL analyses can only derive an overall effect of genetic variants on the quantitative trait in a specific group. It is a big challenge to obtain the individual-level QTL effect, which is necessary for accurate testing and precise characterization. Here, we first proposed an individualized QTL index (IQI) that represents the degree of regulation between genetic variants and the trait for each individual. Based on IQI, Differential QTL (DQ) analysis framework was presented to accurately detect the case-control differences in more detail. In addition, IQI can be a new feature/biomarker applied to various accurate bioinformatics analysis, such as differential analysis, disease prediction, and survival analysis. Overall, IQI affords a new perspective on pathogenic mechanisms and will facilitate the study of genetic regulation more detailedly and precisely.

bioinformatics↗

High throughput protein serial crystallography using a grease matrix and a large-area support film

Serial femtosecond crystallography (SFX) using ultrashort pulses from X-ray free- electron lasers (XFELs) enables the determination of crystal structures at room temperature while minimizing radiation damage to the samples. This method involves irradiating numerous crystals one by one with XFEL pulses, allowing even the capture snapshots of dynamical structures in biological macromolecules. To achieve this, an efficient sample delivery system is essential for acquiring a large number of diffraction patterns. The most common approach uses a highly viscous grease matrix containing sample crystals, injected into the XFEL path from a narrow nozzle. However, the injection often suffers from clogging issues inside the injector nozzle, resulting in additional challenges such as the need for suitably sized crystals, increased sample consumption and unstable flow rates. Alternatively, a fixed-target approach, which scans a two-dimensional substrate with dispersed samples, can circumvent these issues. However, it must ensure the integrity of biological samples and provide sufficient surface area for efficient data collection. We here present an approach that utilizes a grease matrix and a large-area support film specially designed to address these requirements. This system offers a fast and reliable solution for protein SFX, enabling high-quality structure determination while significantly reducing sample consumption.

molecular biology↗

Pyruvate and Related Energetic Metabolites Modulate Resilience Against High Genetic Risk for Glaucoma

A glaucoma polygenic risk score (PRS) can effectively identify disease risk, but some individuals with high PRS do not develop glaucoma. Factors contributing to this resilience remain unclear. Using 4,658 glaucoma cases and 113,040 controls in a cross-sectional study of the UK Biobank, we investigated whether plasma metabolites enhanced glaucoma prediction and if a metabolomic signature of resilience in high-genetic-risk individuals existed. Logistic regression models incorporating 168 NMR-based metabolites into PRS-based glaucoma assessments were developed, with multiple comparison corrections applied. While metabolites weakly predicted glaucoma (Area Under the Curve=0.579), they offered marginal prediction improvement in PRS-only-based models (P=0.004). We identified a metabolomic signature associated with resilience in the top glaucoma PRS decile, with elevated glycolysis-related metabolites--lactate (P=8.8E-12), pyruvate (P=1.9E-10), and citrate (P=0.02)--linked to reduced glaucoma prevalence. These metabolites combined significantly modified the PRS-glaucoma relationship (Pinteraction=0.011). Higher total resilience metabolite levels within the highest PRS quartile corresponded to lower glaucoma prevalence (Odds Ratiohighest vs. lowest total resilience metabolite quartile=0.71, 95% Confidence Interval=0.64-0.80). As pyruvate is a foundational metabolite linking glycolysis to tricarboxylic acid cycle metabolism and ATP generation, we pursued experimental validation for this putative resilience biomarker in a human-relevant Mus musculus glaucoma model. Dietary pyruvate mitigated elevated intraocular pressure (P=0.002) and optic nerve damage (P<0.0003) in Lmx1bV265D mice. These findings highlight the protective role of pyruvate-related metabolism against glaucoma and suggest potential avenues for therapeutic intervention.

genomics↗

Decoding cellular transcriptional regulatory networks governing wheat inflorescence development

Wheat inflorescence architecture, particularly spikelet and floret development, is critical for grain yield. To decode the cellular transcriptional regulatory network (cTRN) underlying wheat inflorescence development, we integrated multiple single-cell omics technologies to construct a spatiotemporal atlas of transcriptional and chromatin accessibility dynamics. This comprehensive analysis identified 20 cell types, 7,211 cell type-specific genes and 152,333 cell type-specific accessible chromatin regions (csACRs) in the wheat inflorescence. Trajectory analysis identified two sub-clusters of proliferating cells as the origins of spikelet and floret formation, deviating from the traditional developmental model. Key transcription factors and hormone-related genes in the cTRN, along with the csACRs, providing new targets for modulating wheat inflorescence architecture. Our findings provide a high-resolution resource for crop inflorescence research and establish a paradigm for applying spatiotemporal single-cell omics analysis to plant biology.

plant biology↗

Local nucleolar surveillance mechanisms maintain rDNA stability

The nucleoli are subdomains of the nucleus that form around actively transcribed ribosomal RNA (rRNA) genes. The highly repetitive and transcribed nature of the rRNA genes (rDNA) by RNA polymerase I (Pol I) poses a challenge for DNA repair and replication machineries. Here, we profile the nucleolar proteome and the chromatin landscape of stalled replication sites upon rDNA damage to characterize the early steps of nucleolar DNA damage response (nDDR). We observed early dynamics in nucleolar-nucleoplasmic proteome localization and identified nucleolar replication stress signatures involving chromatin remodeling networks, transcription-replication conflicts and DNA repair. Our findings define localized surveillance mechanisms that activate the nDDR. Further, we identified that upon rDNA damage, nucleolar RNA Polymerase (Pol) II binds to intergenic rDNA sequences and generates R-loops (DNA:RNA hybrid structures) that are essential for recruiting nDDR factors. Using a boutique CRISPR-Cas9 synthetic lethal screen of DNA repair factors with inhibitors of RNA Pol I transcription, we identified an unexpected protective role for the DNA translocase RAD54L in nDDR. Loss of Rad54L increases nucleolar R-loops and rDNA damage leading to defects in nucleolar structure and enhanced sensitivity to PARP and RNA Pol I inhibitors. Altogether, our study uncovers localized surveillance networks within the nucleolus that respond to rDNA damage. These insights expand our understanding of the molecular mechanisms governing nDDR and opens new avenues for developing nDDR-targeting therapies.

molecular biology↗

Reliable amplification of highly repetitive or low complexity sequence DNA enabled by superhelicase-mediated isothermal amplification

PCR is a cornerstone of molecular biology, but many biologically important DNA templates remain difficult to amplify. Long tandem repeats, low-complexity tracts, and sequences with extreme base composition often yield low product levels, smeared bands, stutter products, or truncated amplicons. These failures can arise because repeated cycles of thermal denaturation and reannealing promote off-register annealing, polymerase slippage, secondary-structure formation, and incomplete extension. Previously, we developed SSB-Helicase Assisted Rapid PCR (SHARP), an isothermal amplification method in which an engineered superhelicase and single-stranded DNA-binding protein replace the thermal melting step of PCR with enzymatic strand separation. Here, we tested whether SHARP can improve amplification of templates that are refractory to conventional PCR. SHARP robustly amplified up to six identical tandem repeats of the Widom 601 nucleosome-positioning sequence and up to 35 identical ankyrin repeats, targets that were poorly amplified by conventional PCR under the conditions tested. SHARP also amplified templates with extreme base composition, including a 95% AT-rich template and GC-rich templates (up to ~95% GC), as well as a 99-repeat CGG tract associated with Fragile X syndrome and a CAG/CAA repeat tract from mutant HTT exon 1 associated with Huntington disease. Together, these results show that helicase-driven isothermal amplification can expand access to repetitive and compositionally extreme DNA sequences that are challenging for conventional thermocycling-based PCR.

bioengineering↗

Anatomical Region-Specific Transcriptomic Signatures and the Role of Epithelial Cells in Pterygium Inflammation: A Multi-Omics Analysis

BackgroundThe anatomy of pterygium consists of the head, neck, and body. Prior studies have examined the three parts collectively, yet the treatment methods and their success rates differ based on the anatomical characteristics. In this study, we divide the pterygium tissue into Main (head and neck) and Acc (body) to investigate its pathogenesis across regions. PurposesThis study aims to understand the pathogenesis and identify potential therapeutic targets of pterygium. Through a robust multi-omics analysis of bulk and single-cell RNA sequencing (RNA-seq) data from pterygium patients, we focus on the expression of inflammatory and mitochondrial energy pathways and identify potential genes responsible for the upregulated pathways in pterygium. MethodsWe collected bulk RNA-seq data from six pterygium patients and single-cell RNA-seq data from two pterygium patients. We then investigated the pathway enrichment, pathway correlation, differential gene expressions, protein-protein interactions, and cell-cell communications of pterygium. ResultsFrom the analysis of bulk RNA-seq data, the distribution of sample points from the principal component analysis plot and the pathways enriched from the Gene Ontology analysis showed distinct expression patterns in the Acc group compared to the Main and control groups. This suggested the need to separate the Main and Acc regions within pterygium samples and utilize single-cell RNA-seq data to understand the differences between the Main and control groups that the bulk data could not capture. The annotation of integrated single-cell data revealed a cluster of epithelial cells containing only pterygium samples. Cells from this cluster exhibited significant contributions to the ANGPTL, IL1, and KLK signaling networks in the cell-cell communication analysis. We also observed significant upregulation of the cells in the inflammatory pathways related to integrated stress response and the renin-angiotensin-aldosterone system, both of which showed high correlations with energy metabolism pathways. Significant changes in the expression of multiple pro-inflammatory, antioxidant, and immune-related genes were also identified. ConclusionThe different expression patterns between the Main and Acc groups suggest the need to consider different anatomical regions separately in future studies of pterygium. Additionally, the significant role epithelial cells from the Main group play in the inflammation of pterygium presents a potential clinical approach to the disease.

bioinformatics↗