Germline regulatory element of Oct-4 specific for the totipotent cycle of embryonal cells
TL;DR: Oct-4 expression in the germline is regulated separately from epiblast expression, and this provides the first marker for the identification of totipotent cells in the embryo, and suggests that expression of Oct-4 in the Totipotent cycle is dependent on a set of factors unique to the germ line.
Abstract: The totipotent stem cells of the pregastrulation mouse embryo which give rise to all embryonic somatic tissues and germ cells express Oct-4. The expression is downregulated during gastrulation and is thereafter only maintained in the germline lineage. Oct-4/lacZ transgenes were used to determine how this pattern of expression was achieved, and resulted in the identification of two separate regulatory elements. The distal element drives Oct-4 expression in preimplantation embryos, in migratory and postmigratory primordial germ cells but is inactive in cells of the epiblast. In cell lines this element is specifically active in embryonic stem and embryonic germ cells. The proximal element directs the epiblast-specific expression pattern, including downregulation during gastrulation; in cell lines its activity is restricted to epiblast-derived cells. Thus, Oct-4 expression in the germline is regulated separately from epiblast expression. This provides the first marker for the identification of totipotent cells in the embryo, and suggests that expression of Oct-4 in the totipotent cycle is dependent on a set of factors unique to the germline.
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TL;DR: It is reported that the activity of Oct4 is essential for the identity of the pluripotential founder cell population in the mammalian embryo and also determines paracrine growth factor signaling from stem cells to the trophectoderm.
3,461 citations
Cites background from "Germline regulatory element of Oct-..."
...Maternal gene products depos- 1990b; Yeom et al., 1996; Pesce et al., 1998)....
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...Cel- embryonal carcinoma (EC), embryonic stem (ES), and lular differentiation and segregation of developmental embryonic germ (EG) cells (Okamoto et al., 1990; Rosner lineage commence at the end of cleavage with compac- et al., 1990; Yeom et al., 1996)....
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TL;DR: By integrating RNA interference–mediated depletion of Oct4 and Nanog with microarray expression profiling, it is demonstrated that these factors can activate or suppress transcription, and it is shown that common core downstream targets are important to keep ES cells from differentiating.
Abstract: Oct4 and Nanog are transcription factors required to maintain the pluripotency and self-renewal of embryonic stem (ES) cells. Using the chromatin immunoprecipitation paired-end ditags method, we mapped the binding sites of these factors in the mouse ES cell genome. We identified 1,083 and 3,006 high-confidence binding sites for Oct4 and Nanog, respectively. Comparative location analyses indicated that Oct4 and Nanog overlap substantially in their targets, and they are bound to genes in different configurations. Using de novo motif discovery algorithms, we defined the cis-acting elements mediating their respective binding to genomic sites. By integrating RNA interference-mediated depletion of Oct4 and Nanog with microarray expression profiling, we demonstrated that these factors can activate or suppress transcription. We further showed that common core downstream targets are important to keep ES cells from differentiating. The emerging picture is one in which Oct4 and Nanog control a cascade of pathways that are intricately connected to govern pluripotency, self-renewal, genome surveillance and cell fate determination.
2,489 citations
TL;DR: It is shown that cell lines can be derived from the epiblast, a tissue of the post-implantation embryo that generates the embryo proper, and interrogated to understand how pluripotent cells generate distinct fates during early development.
Abstract: The application of human embryonic stem (ES) cells in medicine and biology has an inherent reliance on understanding the starting cell population. Human ES cells differ from mouse ES cells and the specific embryonic origin of both cell types is unclear. Previous work suggested that mouse ES cells could only be obtained from the embryo before implantation in the uterus. Here we show that cell lines can be derived from the epiblast, a tissue of the post-implantation embryo that generates the embryo proper. These cells, which we refer to as EpiSCs (post-implantation epiblast-derived stem cells), express transcription factors known to regulate pluripotency, maintain their genomic integrity, and robustly differentiate into the major somatic cell types as well as primordial germ cells. The EpiSC lines are distinct from mouse ES cells in their epigenetic state and the signals controlling their differentiation. Furthermore, EpiSC and human ES cells share patterns of gene expression and signalling responses that normally function in the epiblast. These results show that epiblast cells can be maintained as stable cell lines and interrogated to understand how pluripotent cells generate distinct fates during early development.
2,134 citations
TL;DR: It is demonstrated that early developmental enhancers are epigenetically pre-marked in hESCs and indicate an unappreciated role of H3K27me3 at distal regulatory elements.
Abstract: Cell-fate transitions involve the integration of genomic information encoded by regulatory elements, such as enhancers, with the cellular environment. However, identification of genomic sequences that control human embryonic development represents a formidable challenge. Here we show that in human embryonic stem cells (hESCs), unique chromatin signatures identify two distinct classes of genomic elements, both of which are marked by the presence of chromatin regulators p300 and BRG1, monomethylation of histone H3 at lysine 4 (H3K4me1), and low nucleosomal density. In addition, elements of the first class are distinguished by the acetylation of histone H3 at lysine 27 (H3K27ac), overlap with previously characterized hESC enhancers, and are located proximally to genes expressed in hESCs and the epiblast. In contrast, elements of the second class, which we term 'poised enhancers', are distinguished by the absence of H3K27ac, enrichment of histone H3 lysine 27 trimethylation (H3K27me3), and are linked to genes inactive in hESCs and instead are involved in orchestrating early steps in embryogenesis, such as gastrulation, mesoderm formation and neurulation. Consistent with the poised identity, during differentiation of hESCs to neuroepithelium, a neuroectoderm-specific subset of poised enhancers acquires a chromatin signature associated with active enhancers. When assayed in zebrafish embryos, poised enhancers are able to direct cell-type and stage-specific expression characteristic of their proximal developmental gene, even in the absence of sequence conservation in the fish genome. Our data demonstrate that early developmental enhancers are epigenetically pre-marked in hESCs and indicate an unappreciated role of H3K27me3 at distal regulatory elements. Moreover, the wealth of new regulatory sequences identified here provides an invaluable resource for studies and isolation of transient, rare cell populations representing early stages of human embryogenesis.
2,028 citations
TL;DR: A role for Dicer, and, by implication, the RNAi machinery, in maintaining the stem cell population during early mouse development is suggested.
Abstract: To address the biological function of RNA interference (RNAi)-related pathways in mammals, we disrupted the gene Dicer1 in mice. Loss of Dicer1 lead to lethality early in development, with Dicer1-null embryos depleted of stem cells. Coupled with our inability to generate viable Dicer1-null embryonic stem (ES) cells, this suggests a role for Dicer, and, by implication, the RNAi machinery, in maintaining the stem cell population during early mouse development.
1,966 citations
References
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TL;DR: The establishment in tissue culture of pluripotent cell lines which have been isolated directly from in vitro cultures of mouse blastocysts are reported, able to differentiate either in vitro or after innoculation into a mouse as a tumour in vivo.
Abstract: Pluripotential cells are present in a mouse embryo until at least an early post-implantation stage, as shown by their ability to take part hi the formation of chimaeric animals1 and to form teratocarcinomas2. Until now it has not been possible to establish progressively growing cultures of these cells in vitro, and cell lines have only been obtained after teratocarcinoma formation in vivo. We report here the establishment in tissue culture of pluripotent cell lines which have been isolated directly from in vitro cultures of mouse blastocysts. These cells are able to differentiate either in vitro or after innoculation into a mouse as a tumour in vivo. They have a normal karyotype.
8,144 citations
"Germline regulatory element of Oct-..." refers background in this paper
...ES cells are derived from blastocysts, can be grown in culture for many generations and contribute with high frequency to the germline of chimeras (Evans and Kaufman, 1981; Martin, 1981)....
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Book•
01 Jan 1986
TL;DR: Here are recorded the tech- niques for preparing, inserting and analysing DNA sequences, for retroviral infection of mice, for production and use of EC and EK cells as vehicles for engineered sequences and for nuclear transplantation - all against a background of the basic procedures required for pro- ducing and handling the em- bryos.
Abstract: Manipulating the Mouse Embryo: A Laboratory Manual by B. Hogan, F. Constantini and E. Lacy, Cold Spring Havi~ Laboratmy, 1986. $60.00 (332 pages) ISBN 0 87969 175 1 These are heady days for developmental biologists. Prob- lems that have puzzled scientists for centuries seem to be moving tom the realm of abstract philosophy towards practical solo ution. The power of recombinant DNA technology fuels this opti- mism; at last genes can be engineered, inserted, located, monitored, neutralized and their impact on development asses- sed. The prospect of interfering positively, rather than randomly, with the genetic basis for development is real. The prac- tical basis for this optimism, as recorded in this manual, is clearly well founded. It is impressive that so much pro- gress in the genetic manipulation of the mouse has been made so rapidly. Here are recorded the tech- niques for preparing, inserting and analysing DNA sequences, for retroviral infection of em- bryos, for production and use of EC and EK cells as vehicles for engineered sequences and for nuclear transplantation - all this against a background of the basic procedures required for pro- ducing and handling the em- bryos. If there is one critidsm, it is that the format and content of manual do reveal a fashionable, but perhaps a rather narrow, belief that it is by gene injection (or variants of it) alone that the problem of development will be solved. One might expect a laboratory manual entitled Manilmlating the Mouse Embryo to inform about more general practical aspects of mouse em- bryology than are contained here
5,615 citations
"Germline regulatory element of Oct-..." refers background in this paper
...In addition to colonizing the germline, both ES and EG cells can be induced to differentiate extensively in culture, and also to form teratocarcinomas when injected into nude mice (reviewed by Hogan et al., 1994)....
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...Embryonic stem (ES), embryonal carcinoma (EC) and embryonic germ (EG) cells used in this report resemble cells found in the ICM of blastocysts, epiblast cells and primordial germ cells, respectively (reviewed by Robertson, 1987 and Hogan et al., 1994)....
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TL;DR: In this article, the authors described the establishment directly from normal preimplantation mouse embryos of a cell line that forms teratocarcinomas when injected into mice and demonstrated the pluripotency of these embryonic stem cells by the observation that subclonal cultures, derived from isolated single cells, can differentiate into a wide variety of cell types.
Abstract: This report describes the establishment directly from normal preimplantation mouse embryos of a cell line that forms teratocarcinomas when injected into mice. The pluripotency of these embryonic stem cells was demonstrated conclusively by the observation that subclonal cultures, derived from isolated single cells, can differentiate into a wide variety of cell types. Such embryonic stem cells were isolated from inner cell masses of late blastocysts cultured in medium conditioned by an established teratocarcinoma stem cell line. This suggests that such conditioned medium might contain a growth factor that stimulates the proliferation or inhibits the differentiation of normal pluripotent embryonic cells, or both. This method of obtaining embryonic stem cells makes feasible the isolation of pluripotent cells lines from various types of noninbred embryo, including those carrying mutant genes. The availability of such cell lines should made possible new approaches to the study of early mammalian development.
5,496 citations
TL;DR: Assaying the expression of luciferase provides a rapid and inexpensive method for monitoring promoter activity and is estimated to be from 30- to 1,000-fold more sensitive than assaying chloramphenicol acetyltransferase expression.
Abstract: The nucleotide sequence of the luciferase gene from the firefly Photinus pyralis was determined from the analysis of cDNA and genomic clones. The gene contains six introns, all less than 60 bases in length. The 5' end of the luciferase mRNA was determined by both S1 nuclease analysis and primer extension. Although the luciferase cDNA clone lacked the six N-terminal codons of the open reading frame, we were able to reconstruct the equivalent of a full-length cDNA using the genomic clone as a source of the missing 5' sequence. The full-length, intronless luciferase gene was inserted into mammalian expression vectors and introduced into monkey (CV-1) cells in which enzymatically active firefly luciferase was transiently expressed. In addition, cell lines stably expressing firefly luciferase were isolated. Deleting a portion of the 5'-untranslated region of the luciferase gene removed an upstream initiation (AUG) codon and resulted in a twofold increase in the level of luciferase expression. The ability of the full-length luciferase gene to activate cryptic or enhancerless promoters was also greatly reduced or eliminated by this 5' deletion. Assaying the expression of luciferase provides a rapid and inexpensive method for monitoring promoter activity. Depending on the instrumentation employed to detect luciferase activity, we estimate this assay to be from 30- to 1,000-fold more sensitive than assaying chloramphenicol acetyltransferase expression.
3,074 citations
"Germline regulatory element of Oct-..." refers methods in this paper
...Relative β-galactosidase activity was calculated by normalizing the β-galactosidase activity to that of luciferase, both assayed as described elsewhere (De Wet et al., 1987; Wassarman and DePamphilis, 1993)....
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TL;DR: In this paper, a recombinant myeloid leukaemia inhibitory factor (LIF) was used to replace DIA in the maintenance of totipotent ES cell lines that retain the potential to form chimaeric mice.
Abstract: Embryonic stem (ES) cells, the totipotent outgrowths of blastocysts, can be cultured and manipulated in vitro and then returned to the embryonic environment where they develop normally and can contribute to all cell lineages. Maintenance of the stem-cell phenotype in vitro requires the presence of a feeder layer of fibroblasts or of a soluble factor, differentiation inhibitory activity (DIA) produced by a number of sources; in the absence of DIA the ES cells differentiate into a wide variety of cell types. We recently noted several similarities between partially purified DIA and a haemopoietic regulator, myeloid leukaemia inhibitory factor (LIF), a molecule which induces differentiation in M1 myeloid leukaemic cells and which we have recently purified, cloned and characterized. We demonstrate here that purified, recombinant LIF can substitute for DIA in the maintenance of totipotent ES cell lines that retain the potential to form chimaeric mice.
2,140 citations