Open conformation chromatin and pluripotency
- Laboratory for Pluripotent Cell Studies, RIKEN Center for Developmental Biology (CDB), Kobe, Hyogo 650-0047, Japan
This extract was created in the absence of an abstract.
Pluripotency, the ability of a cell to give rise to all of the cells of an organism, is a fascinating and mysterious characteristic of embryonic stem (ES) cells. Recent extensive molecular studies of mouse ES cells have revealed the roles played by transcription factor networks and epigenetic processes in the maintenance of ES cell pluripotency (Niwa 2007). However, no direct evidence to connect these two mechanisms had been reported until in the previous issue of Genes & Development, in which Loh et al. (2007) presented new evidence concerning this missing link.
Transcription factor network to maintain pluripotency
Analysis of transcription factors expressed in ES cells in an undifferentiated state-specific manner has resulted in the identification of several key transcription factors involved in the maintenance of pluripotency. Of these, the POU family transcription factor Oct3/4 is regarded as pivotal because either its loss of function or its overexpression completely abolishes self-renewal and induces differentiation (Niwa 2007). The Sry-related transcription factor Sox2 was first identified as a partner of Oct3/4 working to activate the transcription of target genes (Yuan et al. 1995). However, a recent report has indicated that the unique function of Sox2 may be the indirect activation of Oct3/4 transcription (Masui et al. 2007). The NK2-class homeobox transcription factor Nanog is also regarded as a component of the core transcription factor network along with Oct3/4 and Sox2 because it is required for the maintenance of pluripotency and has a dominant function in supporting the self-renewal of mouse ES cells in the absence of leukemia inhibitory factor (LIF), the essential cytokine in conventional mouse ES cell cultures (Chambers et al. 2003; Mitsui et al. 2003). Since these three genes possess binding sites for all three of these transcription factors, and the transcriptional activation of these genes by Oct3/4 and Sox2 has been confirmed, it may …
