Biology subjects

Narumi, R.

Publications and source records attributed to Narumi, R..

4 recordsLinked to original sources

bioRxiv2024

Priming Epigenetic Landscape at Gene Promoters through Transcriptional Activation in Mammalian Germ Cells

In mammalian germ cells, a cycle of erasing and resetting epigenetic information is crucial for sex-specific gametogenesis and early embryogenesis. Specific chromatin states at promoters allow genes to be expressed at the appropriate time during germ cell development, however, the mechanism that establishes such characteristic chromatin states remains unclear. Here, we show that, in mouse male embryonic germ cells, promoters of developmental and housekeeping genes are selectively protected from de novo DNA methylation, coinciding with their transient upregulation and genome-wide erasure of H3K27me3. Importantly, a specific level of H3K4me3 density at the promoters serves as a potent probe that distinguishes between hypo- and hyper-DNA methylation states. Subsequent restoration of H3K27me3 contributes to establishing bivalent chromatin states that prime genes for activation at later developmental stages. These findings reveal a molecular framework shaping the epigenetic landscape at promoters with long-term effects beyond germ cell development.

genomics↗

bioRxiv2024

Genome-wide epitope identification with single-amino-acid resolution via high-throughput and unbiased peptide analysis

Antibodies are extensively used in biomedical research, clinical fields, and disease treatment. However, to enhance the reproducibility and reliability of antibody-based experiments, it is crucial to have a detailed understanding of the antibodys target specificity and epitope. In this study, we developed a high-throughput and precise epitope analysis method, DECODE (Decoding Epitope Composition by Optimized-mRNA-display, Data analysis, and Expression sequencing). This method allowed identifying patterns of epitopes recognized by monoclonal or polyclonal antibodies at single amino acid resolution and predicted cross-reactivity against the entire protein database. By applying the obtained epitope information, it has become possible to develop a new 3D immunostaining method that increases the penetration of antibodies deep into tissues. Furthermore, to demonstrated the applicability of DECODE to more complex blood antibodies, we performed epitope analysis using serum antibodies from mice with experimental autoimmune encephalomyelitis (EAE). As a result, we were able to successfully identify an epitope that matched the sequence of the peptide inducing the disease model without relying on existing antigen information. These results demonstrate that DECODE can provide high-quality epitope information, improve the reproducibility of antibody-dependent experiments, diagnostics and therapeutics, and contribute to discover pathogenic epitopes from antibodies in the blood.

bioengineering↗

bioRxiv2021

Versatile and multiplexed mass spectrometry-based absolute quantification with cell-free-synthesized internal standard peptides

Preparation of stable isotope-labeled internal standard peptides is crucial for mass spectrometry (MS)-based targeted proteomics. Herein, we developed versatile and multiplexed absolute protein quantification method using MS. A previously developed method based on the cell-free peptide synthesis system, termed MS-based quantification by isotope-labeled cell-free products (MS-QBiC), was improved for multiple peptide synthesis in one-pot reaction. We pluralized the quantification tags used for the quantification of synthesized peptides and thus, made it possible to use cell-free synthesized isotope-labeled peptides as mixtures for the absolute quantification. The improved multiplexed MS-QBiC method was proved to be applied to clarify ribosomal proteins stoichiometry in the ribosomal subunit, one of the largest cellular complexes. The study demonstrates that the developed method enables the preparation of several dozens and even several hundreds of internal standard peptides within a few days for quantification of multiple proteins with only a single-run of MS analysis.

synthetic biology↗

bioRxiv2018

Src-transformed cells hijack mitosis to extrude from the epithelium

At the initial stage of carcinogenesis single mutated cells appear within an epithelium. Mammalian in vitro experiments show that potentially cancerous cells undergo live apical extrusion from normal monolayers. However, the mechanism underlying this process in vivo remains poorly understood. Mosaic expression of the oncogene vSrc in a simple epithelium of the early zebrafish embryo results in apical extrusion of transformed cells. Here we find that during extrusion components of the cytokinetic ring are recruited to adherens junctions of transformed cells, stimulating formation of a misoriented pseudo cytokinetic ring. During extrusion, the ring constricts and separates the basal from the apical part of the cell releasing both from the epithelium. This process requires cell cycle progression and occurs immediately after vSrc-transformed cell enters mitosis. To achieve extrusion, vSrc coordinates cell cycle progression, junctional integrity, cell survival and apicobasal polarity. Without vSrc, modulating these cellular processes reconstitutes vSrc-like extrusion, confirming their sufficiency for this process.

cell biology↗