Hypoblast from human pluripotent stem cells regulates epiblast development.

Recently, several studies using cultures of human embryos together with single-cell RNA-seq analyses have revealed differences between humans and mice, necessitating the study of human embryos. Despite the importance of human embryology, ethical and legal restrictions have limited post-implantation-stage studies. Thus, recent efforts have focused on developing in vitro self-organizing models using human stem cells.

mRNA-based generation of marmoset PGCLCs capable of differentiation into gonocyte-like cells.

Primate germ cell development remains largely unexplored due to limitations in sample collection and the long duration of development. In mice, primordial germ cell-like cells (PGCLCs) derived from pluripotent stem cells (PSCs) can develop into functional gametes by in vitro culture or in vivo transplantation. Such PGCLC-mediated induction of mature gametes in primates is highly useful for understanding human germ cell development.

Capturing human trophoblast development with naive pluripotent stem cells in vitro.

Trophoblasts are extraembryonic cells that are essential for maintaining pregnancy. Human trophoblasts arise from the morula as trophectoderm (TE), which, after implantation, differentiates into cytotrophoblasts (CTs), syncytiotrophoblasts (STs), and extravillous trophoblasts (EVTs), composing the placenta. Here we show that naïve, but not primed, human pluripotent stem cells (PSCs) recapitulate trophoblast development.

Pluripotent stem cells for the study of early human embryology.

Forty years have passed since the first pluripotent stem cells (PSCs), mouse embryonic stem cells (ESCs), were established. Since then, several PSCs have been reported, including human ESCs in 1998, mouse epiblast stem cells (EpiSCs) in 2007, induced PSCs (iPSCs) in 2006 and 2007, and naïve human PSCs in 2014. Naïve PSCs are thought to correspond to pre-implantation epiblast cells, whereas conventional (or primed) human PSCs correspond to post-implantation epiblast cells.

Cell-type dependent enhancer binding of the EWS/ATF1 fusion gene in clear cell sarcomas.

Clear cell sarcoma (CCS) is a rare soft tissue sarcoma caused by the EWS/ATF1 fusion gene. Here, we established induced pluripotent stem cells (iPSCs) from EWS/ATF1-controllable murine CCS cells harboring sarcoma-associated genetic abnormalities. Sarcoma-iPSC mice develop secondary sarcomas immediately after EWS/ATF1 induction, but only in soft tissue.

Derivation of ground-state female ES cells maintaining gamete-derived DNA methylation.

Inhibitors of Mek1/2 and Gsk3β, known as 2i, enhance the derivation of embryonic stem (ES) cells and promote ground-state pluripotency in rodents. Here we show that the derivation of female mouse ES cells in the presence of 2i and leukaemia inhibitory factor (2i/L ES cells) results in a widespread loss of DNA methylation, including a massive erasure of genomic imprints. Despite this global loss of DNA methylation, early-passage 2i/L ES cells efficiently differentiate into somatic cells, and this process requires genome-wide de novo DNA methylation.

Pluripotent stem cell models of Blau syndrome reveal an IFN-γ-dependent inflammatory response in macrophages.

Background: Blau syndrome, or early-onset sarcoidosis, is a juvenile-onset systemic granulomatosis associated with a mutation in nucleotide-binding oligomerization domain 2 (NOD2). The underlying mechanisms of Blau syndrome leading to autoinflammation are still unclear, and there is currently no effective specific treatment for Blau syndrome.

Objectives: To elucidate the mechanisms of autoinflammation in patients with Blau syndrome, we sought to clarify the relation between disease-associated mutant NOD2 and the inflammatory response in human samples.

Behavior of leucine-rich repeat-containing G-protein coupled receptor 5-expressing cells in the reprogramming process.

It remains unclear what cells are proper for the generation of induced pluripotent stem cells (iPSCs). Leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5) is well known as a tissue stem cell and progenitor marker, both of which are reported to be sensitive to reprogramming. In the present study, we examined the reprogramming behavior of Lgr5-expressing cells (Lgr5+ cells).

Cellular context-dependent consequences of Apc mutations on gene regulation and cellular behavior.

The spectrum of genetic mutations differs among cancers in different organs, implying a cellular context-dependent effect for genetic aberrations. However, the extent to which the cellular context affects the consequences of oncogenic mutations remains to be fully elucidated. We reprogrammed colon tumor cells in an Apc (adenomatous polyposis coli) mouse model, in which the loss of the Apc gene plays a critical role in tumor development and subsequently, established reprogrammed tumor cells (RTCs) that exhibit pluripotent stem cell (PSC)-like signatures of gene expression.

An EWS-FLI1-Induced Osteosarcoma Model Unveiled a Crucial Role of Impaired Osteogenic Differentiation on Osteosarcoma Development.

EWS-FLI1, a multi-functional fusion oncogene, is exclusively detected in Ewing sarcomas. However, previous studies reported that rare varieties of osteosarcomas also harbor EWS-ETS family fusion. Here, using the doxycycline-inducible EWS-FLI1 system, we established an EWS-FLI1-dependent osteosarcoma model from murine bone marrow stromal cells.

Induced pluripotent stem cell technology for dissecting the cancer epigenome.

Cancer arises through the accumulation of both genetic and epigenetic alterations. Although the causal role of genetic mutations on cancer development has been established in vivo, similar evidence for epigenetic alterations is limited. Moreover, mutual interactions between genetic mutations and epigenetic alterations remain unclear.

[Application of reprogramming technology for cancer research].

Cancer is generally developed through accumulation of multiple genetic mutations. Epigenetic abnormalities of DNA methylation and histone modification patterns were also found in most cancer cells. Although induced pluripotent stem cells (iPSCs) can be generated through epigenetic reorganization without affecting the underlying genomic sequencing, they have some shared characteristics with cancer cells, which include unlimited growth potential.

Reducing DNA methylation suppresses colon carcinogenesis by inducing tumor cell differentiation.

The forced reduction of global DNA methylation suppresses tumor development in several cancer models in vivo. Nevertheless, the mechanisms underlying these suppressive effects remain unclear. In this report, we describe our findings showing that a genome-wide reduction in the DNA methylation levels induces cellular differentiation in association with decreased cell proliferation in Apc (Min/+) mouse colon tumor cells in vivo.

Application of iPS cell technology to cancer epigenome study: uncovering the mechanism of cell status conversion for drug resistance in tumor.

Recent studies imply that cancer cells possess the ability to reversibly change their properties between a drug sensitive state and a drug resistant state accompanied by epigenetic changes. This evidence indicates that better understanding of cancer epigenetics is important for efficient cancer therapies. Nevertheless, it had been difficult to deeply examine the epigenetic mechanisms because of lack of the tools to actively modify coordinated epigenetic events.

Epigenetic regulation leading to induced pluripotency drives cancer development in vivo.

Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) by the transient expression of reprogramming factors. During the reprogramming process, somatic cells acquire the ability to undergo unlimited proliferation, which is also an important characteristic of cancer cells, while their underlying DNA sequence remains unchanged. Based on the characteristics shared between pluripotent stem cells and cancer cells, the potential involvement of the factors leading to reprogramming toward pluripotency in cancer development has been discussed.

Premature termination of reprogramming in vivo leads to cancer development through altered epigenetic regulation.

Cancer is believed to arise primarily through accumulation of genetic mutations. Although induced pluripotent stem cell (iPSC) generation does not require changes in genomic sequence, iPSCs acquire unlimited growth potential, a characteristic shared with cancer cells. Here, we describe a murine system in which reprogramming factor expression in vivo can be controlled temporally with doxycycline (Dox).

Chromatin accessibility at a STAT3 target site is altered prior to astrocyte differentiation.

DNA demethylation of astrocyte-specific gene promoters and STAT3 activation in neural precursor cells (NPCs) are essential for astrogliogenesis in the developing brain. To date, it remains unclear whether DNA methylation is the sole epigenetic determinant responsible for suppressing astrocyte-specific genes. Here, we used mouse embryonic stem cells (TKO ESCs) that lacked all 3 DNA methyltransferase genes, Dnmt1, Dnmt3a, and Dnmt3b, and thereby exhibit complete demethylation of the astrocyte-specific glial fibrillary acidic protein (Gfap) gene promoter.

EWS/ATF1 expression induces sarcomas from neural crest-derived cells in mice.

Clear cell sarcoma (CCS) is an aggressive soft tissue malignant tumor characterized by a unique t(12;22) translocation that leads to the expression of a chimeric EWS/ATF1 fusion gene. However, little is known about the mechanisms underlying the involvement of EWS/ATF1 in CCS development. In addition, the cellular origins of CCS have not been determined.

Cellular reprogramming and cancer development.

Cancer develops through the accumulation of genetic and epigenetic abnormalities. The role of genetic alterations in cancer development has been demonstrated by reverse genetic approaches. However, evidence indicating the functional significance of epigenetic abnormalities remains limited due to the lack of means to actively modify coordinated epigenetic regulations in the genome.

Treatment of a mouse model of spinal cord injury by transplantation of human induced pluripotent stem cell-derived long-term self-renewing neuroepithelial-like stem cells.

Because of their ability to self-renew, to differentiate into multiple lineages, and to migrate toward a damaged site, neural stem cells (NSCs), which can be derived from various sources such as fetal tissues and embryonic stem cells, are currently considered to be promising components of cell replacement strategies aimed at treating injuries of the central nervous system, including the spinal cord. Despite their efficiency in promoting functional recovery, these NSCs are not homogeneous and possess variable characteristics depending on their derivation protocols. The advent of induced pluripotent stem (iPS) cells has provided new prospects for regenerative medicine.

Committed neuronal precursors confer astrocytic potential on residual neural precursor cells.

During midgestation, mammalian neural precursor cells (NPCs) differentiate only into neurons. Generation of astrocytes is prevented at this stage, because astrocyte-specific gene promoters are methylated. How the subsequent switch from suppression to expression of astrocytic genes occurs is unknown.

Characterization of the human herpesvirus 6 U69 gene product and identification of its nuclear localization signal.

To elucidate the function of the U69 protein kinase of human herpesvirus 6 (HHV-6) in vivo, we first analyzed its subcellular localization in HHV-6-infected Molt 3 cells by using polyclonal antibodies against the U69 protein. Immunofluorescence studies showed that the U69 signal localized to the nucleus in a mesh-like pattern in both HHV-6-infected and HHV6-transfected cells. A computer program predicted two overlapping classic nuclear localization signals (NLSs) in the N-terminal region of the protein; this NLS motif is highly conserved in the N-terminal region of most of the herpesvirus protein kinases examined to date.