Embryonic stem cells articles within Nature

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  • News & Views |

    Enhancer sequences increase gene transcription with the help of a co-activator complex, the Mediator. Another protein complex — cohesin — seems to work with Mediator to bring together enhancers and promoters. See Article p. 430

    • Rolf Ohlsson

  • Brief Communications Arising |

    • Sanjay K. Singh
    • , Mohamedi N. Kagalwala
    •  & Sadhan Majumder

  • Article |

    Neurons of the peripheral nervous system need survival factors to prevent their death during development. Most in the central nervous system do not. Why are peripheral neurons so needy? Here it is shown that the neurotrophin receptors TrkA and TrkC, expressed at high levels by many peripheral nervous system neurons, behave as dependence receptors: they instruct neurons to die if there is no ligand around. By contrast, TrkB, expressed mainly in the central nervous system, does not signal death in the absence of ligand.

    • Vassiliki Nikoletopoulou
    • , Heiko Lickert
    •  & Yves-Alain Barde

  • Editorial |

    Congress must act quickly to save US stem-cell research.

  • Article |

    Gene activation may involve the formation of a DNA loop that connects enhancer-bound transcription factors with the transcription apparatus at the core promoter. But this process is not well understood. Here, two proteins, mediator and cohesin, are shown to connect the enhancers and core promoters of active genes in embryonic stem cells. These proteins seem to generate cell-type-specific DNA loops linked to the gene expression program of each cell.

    • Michael H. Kagey
    • , Jamie J. Newman
    •  & Richard A. Young

  • Letter |

    The rat is a animal model widely used for studying human physiology and disease, but functional genomics and genetic research have been stifled by the limited availability of gene targeting tools. These authors have established gene targeting by homologous recombination in rat embryonic stem cells, and have generated p53 gene knockout rats for the first time.

    • Chang Tong
    • , Ping Li
    •  & Qi-Long Ying

  • Article |

    Zscan4 is shown to be involved in maintaining telomeres in embryonic stem (ES) cells. Only 5% of ES cells express Zscan4 at a given time, but nearly all ES cells activate Zscan4 at least once within nine passages. The transient Zscan4-positive state is associated with rapid telomere extension by telomere recombination and upregulation of meiosis–specific homologous recombination genes. Knocking down Zscan4 shortens telomeres, increases karyotype abnormalities and spontaneous sister chromatid exchange, and slows down cell proliferation until reaching crisis by eight passages.

    • Michal Zalzman
    • , Geppino Falco
    •  & Minoru S. H. Ko

  • Letter |

    To study the changes in chromatin structure that accompany zygotic genome activation and pluripotency during the maternal–zygotic transition (MZT), the genomic locations of histone H3 modifications and RNA polymerase II have been mapped during this transition in zebrafish embryos. H3 lysine 27 trimethylation and H3 lysine 4 trimethylation are only detected after MZT; evidence is provided that the bivalent chromatin domains found in cultured embryonic stem cells also exist in embryos.

    • Nadine L. Vastenhouw
    • , Yong Zhang
    •  & Alexander F. Schier

  • Letter |

    Endogenous retroviruses (ERVs) are widely dispersed in mammalian genomes, and are silenced in somatic cells by DNA methylation. Here, an ERV silencing pathway independent of DNA methylation is shown to operate in embryonic stem cells. The pathway involves the histone H3K9 methyltransferase ESET and might be important for ERV silencing during the stages in embryogenesis when DNA methylation is reprogrammed.

    • Toshiyuki Matsui
    • , Danny Leung
    •  & Yoichi Shinkai

  • News & Views |

    Embryonic stem cells can create copies of themselves, but can also mature into almost any type of cell in the body. Tiny gene regulators called microRNAs are now shown to have a role in directing these properties.

    • Frank J. Slack

  • Letter |

    Much of the mammalian genome is derived from retroelements, a significant proportion of which are endogenous retroviruses (ERVs). ERVs are transcriptionally silenced during early embryogenesis by histone and DNA methylation, but the initiators of this process are largely unknown. Here, deletion of KAP1 is shown to lead to a marked upregulation of a range of ERVs in mouse embryonic stem cells and in early embryos.

    • Helen M. Rowe
    • , Johan Jakobsson
    •  & Didier Trono

  • Article |

    The differentiation of an embryonic stem cell (ESC) requires both suppression of the self-renewal process and activation of the specific differentiation pathway. The let-7 family of microRNAs (miRNAs) are now shown to suppress the self-renewal program in cells that are normally unable to silence this program, whereas introduction of ESC cell cycle regulating miRNAs blocks the action of let-7. Thus, the interplay between these two groups of miRNAs dictates cell fate.

    • Collin Melton
    • , Robert L. Judson
    •  & Robert Blelloch

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