Biology subjects

Higashi, K.

Publications and source records attributed to Higashi, K..

12 recordsLinked to original sources

bioRxiv2026

An iPSC-based experimental framework for investigating phenotypic variation associated with Jomon ancestry in the present-day Japanese population

Ancestry-related genomic variation may contribute to phenotypic diversity. However, its cellular consequences remain difficult to evaluate. To address this, we developed a human induced pluripotent stem cell (hiPSC)-based framework for investigating such phenotypes. We used the Japanese population as a model of Jomon-related and continental East Asian ancestry admixture. Jomon ancestry, estimated using the Jomon allele score (JAS), was associated with clinical measures, including renal-related traits and serum triglycerides in 34,152 Tohoku Medical Megabank participants. Peripheral blood mononuclear cell transcriptomics of donors from the upper and lower extremes of the JAS distribution (n = 10) suggested group-level differences in immune-related gene expression. To test whether the serum triglyceride association coincided with hepatic cellular phenotypes, we differentiated hiPSCs from these donors into hepatocyte-like cells. Neither intracellular triglycerides nor lipid-related gene expression differed between groups. These findings highlight the value of a genetically characterized hiPSC-based framework for investigating ancestry-associated phenotypes across cellular contexts.

genomics↗

bioRxiv2026

Oncogenic NPM-ALK reprograms the TGM1 1 interactome toward oncogenic signaling and transcriptional states

Oncogenic NPM-ALK drives aberrant signaling networks that promote malignant phenotypes; however, the molecular mechanisms linking oncogenic signaling to downstream cellular programs remain incompletely understood. Among candidate regulatory factors, transglutaminase 1 (TGM1) has not been functionally characterized in this context. Here, we investigated the role of TGM1 in NPM-ALK-expressing cells by combining proximity-dependent proteomics with functional analyses. Using a TurboID- based approach, we mapped the TGM1-associated protein network and identified extensive remodeling of this network upon NPM-ALK expression. Proteomic analyses revealed that NPM-ALK reduced TGM1-associated proteins involved in genome maintenance and DNA repair, while enhancing associations with proteins linked to cytoplasmic translation and PI3K-AKT signaling pathways. Consistent with these findings, TGM1 deficiency impaired cell proliferation without significantly affecting cell viability, indicating a specific role in maximal proliferative capacity. Furthermore, proteomic and functional analyses suggested a link between TGM1 and AKT signaling pathways. Together, these findings suggest that oncogenic NPM-ALK reprograms the TGM1 interactome toward oncogenic signaling and transcriptional states, positioning TGM1 within signaling networks associated with proliferative cellular phenotypes.

molecular biology↗

bioRxiv2026

Benchmarking long-context genome language models on biosynthetic gene clusters

Recent advances in language models for natural language processing have spread to the field of genomics, driving the development of genome language models (gLMs) to decipher genomic information. Cutting-edge long-context gLMs are promising approaches for understanding and designing biological complexity, but their evaluation remains underdeveloped. In this study, we introduce BGCs-Bench, a unified benchmark focused on biosynthetic gene clusters for assessing long-range genomic modeling on three downstream tasks: biosynthetic class prediction, taxonomic classification and coding sequence annotation. Using BGCs-Bench, we perform systematic and layer-wise evaluations of the embedding representations of long-context gLMs, demonstrating that layer selection is crucial for downstream task performance. In addition to the evaluation results, the logit lens analysis of autoregressive gLMs suggests that StripedHyena-based models consist of earlier layers to encode biologically meaningful information from input DNA sequences and deeper layers to optimize embeddings for sequence generation. These findings provide insights for more effective development and application of long-context gLMs.

bioinformatics↗

bioRxiv2025

Cohesin prevents local mixing of condensed euchromatic domains in living human cells

The human genome is folded into chromatin loops by the cohesin complex, forming functional chromatin domains that underlie transcription and DNA replication/repair. However, how cohesin organizes these domains in living cells, especially in active euchromatin, remains elusive. To address this question, we combined single-nucleosome imaging/tracking and super-resolution 3D-structured illumination microscopy (3D-SIM) with euchromatin-specific labeling of histone H3.3. Using this nanoscopic approach, we revealed that euchromatin forms condensed domains that are constrained by cohesin-mediated loops. This organization refines the classical textbook view of euchromatin as largely open, in line with emerging evidence. Transcription machinery appears to be located near the condensed domain surfaces/borders. Cohesin loss increased nucleosome fluidity within these domains without altering their overall compaction, leading to local mixing of domains and compromising transcriptional insulation. These findings uncover an unexpected physical role of cohesin in maintaining the integrity of condensed euchromatic domains and ensuring proper higher-order regulation of gene expression.

cell biology↗

bioRxiv2024

Automated Harmonization and Large-Scale Integration of Heterogeneous Biomedical Sample Metadata Using Large Language Models

The exponential growth of biomedical data has created an urgent need for efficient integration and analysis of heterogeneous sample metadata across studies. However, current methods for harmonizing and standardizing these metadata are largely manual, time-consuming, and prone to inconsistencies. Here, we present a novel computational framework that leverages large language models (LLMs) to automate the harmonization and large-scale integration of diverse biomedical sample metadata. Our approach combines semantic clustering techniques with LLM-driven natural language processing to extract, interpret, and standardize metadata from various sources, including research papers, supplementary tables, and text data from public databases. We demonstrate the efficacy of our framework by applying it to thousands of human gut microbiome papers, successfully extracting and integrating metadata from over 400,000 samples. Our method achieved a 50% recovery rate of manually curated metadata, significantly outperforming traditional rule-based methods. Furthermore, our framework enabled the creation of a unified, searchable database of standardized metadata, facilitating cross-study analyses and revealing previously obscured patterns in microbiome composition across diverse populations and conditions. The scalability and adaptability of our approach suggest its potential applicability to a wide range of biomedical fields, potentially accelerating meta-analyses and fostering new insights from existing data. This work represents a significant advancement in biomedical data integration, offering a powerful tool for researchers to unlock the full potential of accumulated scientific knowledge.

bioinformatics↗

bioRxiv2024

Replication-dependent histone (Repli-Histo) labeling dissects the physical properties of euchromatin/heterochromatin in living human cells.

A string of nucleosomes, where genomic DNA is wrapped around histones, is organized in the cell as chromatin. Chromatin in the cell varies greatly, from euchromatin to heterochromatin, in its genome functions. It is important to understand how heterochromatin is physically different from euchromatin. However, their specific labeling methods in living cells are limited. To address this, we have developed replication-dependent histone labeling (Repli-Histo labeling) to label nucleosomes in euchromatin and heterochromatin based on DNA replication timing. We investigated local nucleosome motion in the four chromatin classes from euchromatin to heterochromatin of living human and mouse cells. We found that more euchromatic regions (earlier replicated regions) show greater nucleosome motion. Notably, the motion profile in each chromatin class persists throughout interphase. Genome chromatin is essentially replicated from regions with greater nucleosome motions, even though the replication timing program is perturbed. Our findings, combined with computational modeling, suggest that earlier replicated regions have more accessibility and local chromatin motion can be a major determinant of genome-wide replication timing.

cell biology↗

bioRxiv2024

Concentration-dependent formation of intersegment interactions in viral droplets of influenza A virus infected cells

The influenza A virus genome consists of eight RNA segments, each incorporated into a virion. It has been proposed that intersegment interactions bundle these segments, and viral inclusions, which contain viral ribonucleoproteins (vRNPs) and Rab11, facilitate this process. However, the locations and mechanisms of intersegment interaction formation remain unclear. To investigate this, we identified comprehensive intersegment interactions in infected cells using customized LIGR-seq. Our results revealed that intersegment interactions in infected cells overlapped with those in the virion and were partially formed through direct RNA-RNA interactions. Additionally, we found that the formation of these interactions was delayed in cells expressing a Rab11 dominant-negative. Furthermore, artificially increasing vRNP concentrations in the nucleus, where intersegment interactions typically do not occur, triggered the formation of these interactions, which again overlapped with those in the virion. These results suggest that intersegment interactions are formed in viral inclusions where progeny vRNPs accumulate.

microbiology↗

bioRxiv2024

Identifying Genetic Variations in emm89 Streptococcus pyogenes Linked to Severe Invasive Infections

Streptococcus pyogenes causes mild human infections as well as life-threatening invasive diseases. Since the mutations known to enhance virulence to date account for only half of the severe invasive infections, additional mechanisms/mutations need to be identified. Here, we conducted a genome-wide association study of emm89 S. pyogenes strains to comprehensively identify pathology-related bacterial genetic factors (SNPs, indels, genes, or k-mers). Japanese (n=311) and global (n=666) cohort studies of strains isolated from invasive or non-invasive infections revealed 17 and 1,075 SNPs/indels and 2 and 169 genes, respectively, that displayed associations with invasiveness. We validated one of them, a non-invasiveness-related point mutation, fhuB T218C, by structure predictions and introducing it into a severe invasive strain and confirmed that the mutant showed slower growth in human blood. Thus, we report novel mechanisms that convert emm89 S. pyogenes to an invasive phenotype and a platform for establishing novel treatments and prevention strategies.

microbiology↗

bioRxiv2023

Chemical genetic interaction linking eIF5A hypusination and mitochondrial integrity

The eukaryotic translation factor eIF5A plays an important role in translation elongation, especially across stretches of prolines and charged amino acids, and in translation termination. eIF5A undergoes hypusination, a post-translational modification unique to this protein, although the role of hypusination in the function of eIF5A remains elusive. Here, we investigated the cellular defects induced by the hypusination inhibitor GC7 (N1-guanyl-1,7-diaminoheptane). Proteome, translatome, and transcriptome analyses indicated that GC7 downregulated a subset of mitochondrial proteins and DNA, causing mitochondrial stress and eliciting the integrated stress response. Chemical genomic screening using barcoded shRNA libraries identified genes encoding proteins involved in polyamine metabolism/transport and MPV17L2, a mitochondrial disease gene homologue whose product regulates mitochondrial translation. Depletion of MPV17L2 caused hypersensitivity to GC7 and phenocopied the effects of GC7 treatment. These results suggest that eIF5A hypusination and MPV17L2 synthetically regulate mitochondrial molecular synthesis and integrity.

cell biology↗

bioRxiv2022

Metagenomic thermometer

Various microorganisms exist in environments, and each of which has an optimal growth temperature (OGT). The relationship between genomic information and OGT of each species has long been studied, and one such study revealed that OGT of prokaryotes can be accurately predicted based on the fraction of seven amino acids (IVYWREL) among all encoded amino-acid sequences in its genome. Extending this discovery, the fraction of IVYWREL among all amino acids encoded in the metagenomic DNA in an environment may reflect the environmental temperature to which the microorganisms have adapted. In the present study, we developed a Metagenomic Thermometer as a means of predicting environmental temperature based on metagenomic sequences. Analysis of 41 metagenomic samples obtained from hot springs of varying temperature revealed that the Metagenomic Thermometer could indeed predict environmental temperature with high accuracy (R2 = 0.75). Although the taxonomic composition of microbial community was substantially affected by pH, the performance of the Metagenomic Thermometer was refractory to changes in community composition. The Metagenomic Thermometer was also applied to 616 human gut metagenomic samples, yielding a reasonably accurate value (i.e., 36.22 {+/-} 1.98{degrees}C) for human body temperature. Our results suggest that environmental temperature can be predicted based on metagenomic sequence data.

bioinformatics↗

bioRxiv2022

A Novel Cytoskeletal Action of Xylosides

Proteoglycan glycosaminoglycan (GAG) chains are attached to a serine residue in the protein through a linkage series of sugars, the first of which is xylose. Xylosides are chemicals which compete with the xylose at the enzyme xylosyl transferase to prevent the attachment of GAG chains to proteins. These compounds have been employed at concentrations in the millimolar range as tools to study the role of GAG chains in proteoglycan function. In the course of our studies with xylosides, we conducted a dose-response curve for xyloside actions on neural cells. To our surprise, we found that concentrations of xylosides in the nanomolar to micromolar range had major effects on cell morphology. These effects are due to changes in cytoskeletal dynamics. Concentrations of xylosides which were effective in altering morphology did not alter GAG chain synthesis rates, nor did they produce any changes in gene expression as determined by RNAseq of treated cells. These observations support a novel action of xylosides on neuronal cells.

cell biology↗

bioRxiv2020

A functional RNA structure in the influenza A virus ribonucleoprotein complex for segment bundling

The influenza A virus genome is segmented into eight viral RNAs (vRNA). Secondary structures on vRNA are thought to be involved in the viral proliferation process, such as intersegment interactions that are necessary for segment bundling. However, the functional RNA structure on vRNA is not well known because the secondary structure of vRNA in virion was partially unwound by binding viral non-specific RNA binding proteins in a sequence-independent manner. Here, we establish the global map of the vRNA secondary structure in virion using the combination of dimethyl sulfate (DMS)-seq and selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE)-seq. By integrating DMS-seq and SHAPE-seq analyses with robust statistical analysis, we inferred quite a few bases paired regions including a pseudoknot structure on segment 5. Notably, when cells were infected with the recombinant virus which had mutations in the pseudoknot structure, the impairment of replication and packaging was observed on the other specific segment. Moreover, we analyzed the comprehensive intersegment RNA interactions in virion by ligation of interacting RNA followed by high-throughput sequencing (LIGR-seq). Our LIGR-seq analysis revealed that the intersegment interactions of the specific segment became less frequent and rearranged in the recombinant virus in concordance with the strength of genome packaging impairment. Our data provide evidence that the functional RNA structure motif on the influenza A virus genome can affect the efficiency of replication and segment bundling through the segment interactions.

microbiology↗