Biology subjects

Nagaoka, S.

Publications and source records attributed to Nagaoka, S..

4 recordsLinked to original sources

bioRxiv2023

Comprehensive comparison of female germ cell development in vitro and in vivo identifies epigenetic gene regulation crucial for oocyte development and embryonic competence

Germ cells are the origin of new individuals. Hence, specifying germ cell identity is crucial for reproduction. The recent establishment of in vitro culture systems for generating oocytes from mouse pluripotent stem cells provides a basis for progress in studies of oogenesis and reproductive technology. However, currently the developmental competence of in vitro generated oocytes is low compared to in vivo grown oocytes. The causes underlying poor oocyte quality remain to be determined. By reconstituting germ cell development in culture from different developmental starting points within gametogenesis, we show that the differentiation of primordial germ cells (PGCs) and primordial germ cell-like cells (PGCLCs) to growing oocytes (GROs), as well as the subsequent growth of follicles are critical culture steps for specifying competence of fully-grown oocytes (FGOs) for preimplantation development. A systematic comparison of transcriptomes of single oocytes having undergone different in vitro culture trajectories identifies genes normally upregulated during oocyte growth to be susceptible for mis-regulation during in vitro oogenesis. Many of such genes have been described as targets of Polycomb repressive complexes (PRCs). Deregulation of Polycomb repression therefore likely perturbs the accumulation of cytoplasmic factors and/or setting of chromatin states in FGOs that are required for embryonic development after fertilization. Conversely, in vitro derived oocytes often displayed failure of zygotic genome activation (ZGA) and abnormal acquisition of 5-hydroxymethylcytosine (5hmC) on maternal chromosomes after activation. In addition, subcellular delocalization of pyruvate dehydrogenase (PDH) and of STELLA were observed suggesting new molecular markers for defective oocyte development. Our study identifies epigenetic regulation at an early stage of oogenesis as crucial for developmental competence and suggests specific in vitro culture steps as targets for improving oocyte quality. HighlightsO_LISingle cell transcriptomics and functional assessment of oocyte development from pluripotent stem cells in culture in a stage-specific manner provides a comprehensive resource for comparisons to oogenesis in vivo. C_LIO_LICulture steps for growth and differentiation of reconstituted follicles are critical for defining embryonic competence of in vitro generated oocytes. C_LIO_LIZygotic genome activation failure and epigenetic impairment are hallmarks of in vitro-generated oocytes that fail to develop after activation or fertilization. C_LIO_LIComputational analysis of gene expression changes and chromatin modification patterns identifies specific gene sets that indicate that Polycomb mediated repression is vulnerable during in vitro folliculogenesis. C_LI

developmental biology↗

bioRxiv2022

Histology-associated transcriptomic heterogeneity in ovarian folliculogenesis revealed by quantitative single-cell RNA-sequencing for tissue sections with DRaqL

High-quality single-cell RNA-sequencing (RNA-seq) with spatial resolution remains challenging. Laser capture microdissection (LCM) is a widely used, potent approach to isolate arbitrarily targeted cells from tissue sections for comprehensive transcriptomics. Here, we developed DRaqL (direct RNA recovery and quenching for LCM), an experimental approach for efficient lysis of single cells isolated by LCM from alcohol- and formalin-fixed sections without RNA purification. Single-cell RNA-seq combined with DRaqL allowed transcriptomic profiling from alcohol-fixed sections with efficiency comparable to that of profiling from freshly dissociated cells, together with effective exon- exon junction profiling. Furthermore, the combination of DRaqL and protease treatment enabled robust and efficient single-cell transcriptome analysis from tissue sections strongly fixed with formalin. Applying this method to mouse ovarian sections, we revealed a transcriptomic continuum of growing oocytes quantitatively associated with oocyte size, and detected oocyte-specific splice isoforms. In addition, our statistical model revealed heterogeneity of the relationship between the transcriptome of oocytes and their size, resulting in identification of a size-transcriptome relationship anomaly in a subset of oocytes. Finally, we identified genes that were differentially expressed in granulosa cells in association with the histological affiliations of granulosa cells to the oocytes, suggesting distinct epigenetic regulations and cell-cycle activities governing the germ-soma relationship. Thus, we developed a versatile, efficient approach for robust single-cell cDNA amplification from tissue sections and provided an experimental platform conducive to high-quality transcriptomics, thereby revealing histology-associated transcriptomic heterogeneity in folliculogenesis in ovarian tissues.

developmental biology↗

bioRxiv2021

A temporally controlled sequence of X-chromosomeinactivation and reactivation defines female mouse in vitro germ cells with meiotic potential

The early mammalian germ cell lineage is characterized by extensive epigenetic reprogramming, which is required for the maturation into functional eggs and sperm. In particular, the epigenome needs to be reset before parental marks can be established and then transmitted to the next generation. In the female germ line, reactivation of the inactive X-chromosome is one of the most prominent epigenetic reprogramming events, and despite its scale involving an entire chromosome affecting hundreds of genes, very little is known about its kinetics and biological function. Here we investigate X-chromosome inactivation and reactivation dynamics by employing a tailor-made in vitro system to visualize the X-status during differentiation of primordial germ cell-like cells (PGCLCs) from female mouse embryonic stem cells (ESCs). We find that the degree of X-inactivation in PGCLCs is moderate when compared to somatic cells and characterized by a large number of genes escaping full inactivation. Nevertheless, PGCLCs that fail to undergo X-inactivation show an abnormal gene expression signature and deficiencies in meiotic entry. Subsequent to X-inactivation we observe gradual step-wise X-reactivation, which is mostly completed by the end of meiotic prophase I. Cells deviating from these progressive kinetics and undergoing X-reactivation too rapidly fail to enter a meiotic trajectory. Our data reveals that a fine-tuned X-inactivation and -reactivation cycle is a critical feature of female germ cell developmental competence towards meiosis and oogenesis

developmental biology↗

bioRxiv2018

Gorilla APOBEC3 restricts SIVcpz and influences lentiviral evolution in great ape cross-species transmissions

Restriction factors including APOBEC3 family proteins have the potential prevent cross-species lentivirus transmissions. Such events as well as ensuing pathogenesis require the viral Vif protein to overcome/neutralize/degrade the APOBEC3 enzymes of the new host species. Previous investigations have focused on the molecular interaction between human APOBEC3s and HIV-1 Vif. However, the evolutionary interplay between lentiviruses and great ape (including human, chimpanzee and gorilla) APOBEC3s has not been fully investigated. Here we demonstrate that gorilla APOBEC3G plays a pivotal role in restricting lentiviral transmission from chimpanzee to gorilla. We also reveal that a sole amino acid substitution in Vif is sufficient to overcome the gorilla APOBEC3G-mediated species barrier. Moreover, the antiviral effects of gorilla APOBEC3D and APOBEC3F are considerably weaker than those of human and chimpanzee counterparts, which can result in the skewed evolution of great ape lentiviruses leading to HIV-1.\n\nHighlightsO_LISIVcpz requires M16E mutation in Vif to counteract gorilla A3G\nC_LIO_LIAcidic residue at position 16 of Vif is crucial to counteract gorilla A3G\nC_LIO_LIGorilla A3D and A3F poorly suppress lentiviral infectivity\nC_LIO_LISIVgor and related HIV-1s counteract human A3D and A3F independently of DRMR motif\nC_LI

microbiology↗