Pluripotency factors in embryonic stem cells regulate differentiation into germ layers.

FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA.
Cell (Impact Factor: 31.96). 06/2011; 145(6):875-89.
Source: PubMed

ABSTRACT Cell fate decisions are fundamental for development, but we do not know how transcriptional networks reorganize during the transition from a pluripotent to a differentiated cell state. Here, we asked how mouse embryonic stem cells (ESCs) leave the pluripotent state and choose between germ layer fates. By analyzing the dynamics of the transcriptional circuit that maintains pluripotency, we found that Oct4 and Sox2, proteins that maintain ESC identity, also orchestrate germ layer fate selection. Oct4 suppresses neural ectodermal differentiation and promotes mesendodermal differentiation; Sox2 inhibits mesendodermal differentiation and promotes neural ectodermal differentiation. Differentiation signals continuously and asymmetrically modulate Oct4 and Sox2 protein levels, altering their binding pattern in the genome, and leading to cell fate choice. The same factors that maintain pluripotency thus also integrate external signals and control lineage selection. Our study provides a framework for understanding how complex transcription factor networks control cell fate decisions in progenitor cells.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The Sox2 transcription factor must be robustly transcribed in embryonic stem (ES) cells to maintain pluripotency. Two gene-proximal enhancers, Sox2 regulatory region 1 (SRR1) and SRR2, display activity in reporter assays, but deleting SRR1 has no effect on pluripotency. We identified and functionally validated the sequences required for Sox2 transcription based on a computational model that predicted transcriptional enhancer elements within 130 kb of Sox2. Our reporter assays revealed three novel enhancers-SRR18, SRR107, and SRR111-that, through the formation of chromatin loops, form a chromatin complex with the Sox2 promoter in ES cells. Using the CRISPR/Cas9 system and F1 ES cells (Mus musculus(129) × Mus castaneus), we generated heterozygous deletions of each enhancer region, revealing that only the distal cluster containing SRR107 and SRR111, located >100 kb downstream from Sox2, is required for cis-regulation of Sox2 in ES cells. Furthermore, homozygous deletion of this distal Sox2 control region (SCR) caused significant reduction in Sox2 mRNA and protein levels, loss of ES cell colony morphology, genome-wide changes in gene expression, and impaired neuroectodermal formation upon spontaneous differentiation to embryoid bodies. Together, these data identify a distal control region essential for Sox2 transcription in ES cells. © 2014 Zhou et al.; Published by Cold Spring Harbor Laboratory Press.
    Genes & development. 12/2014; 28(24):2699-711.
  • [Show abstract] [Hide abstract]
    ABSTRACT: SOX2 is one of the key transcription factors involved in maintenance of neural progenitor identity. However, its function during the process of neural differentiation, including phases of lineage-specification and terminal differentiation, is still poorly understood. Considering growing evidence indicating that SOX2 expression level must be tightly controlled for proper neural development, the aim of this research was to analyze the effects of constitutive SOX2 overexpression on outcome of retinoic acid-induced neural differentiation of pluripotent NT2/D1 cells. We demonstrated that in spite of constitutive SOX2 overexpression, NT2/D1 cells were able to reach final phases of neural differentiation yielding both neuronal and glial cells. However, SOX2 overexpression reduced the number of mature MAP2-positive neurons while no difference in the number of GFAP-positive astrocytes was detected. In-depth analysis at single-cell level showed that SOX2 downregulation was in correlation with both neuronal and glial phenotype acquisitions. Interestingly, while in mature neurons SOX2 was completely downregulated, astrocytes with low level of SOX2 expression were detected. Nevertheless, cells with high level of SOX2 expression were incapable of entering in either of two differentiation pathways, neurogenesis or gliogenesis. Accordingly, our results indicate that fine balance between undifferentiated state and neural differentiation depends on SOX2 expression level. Unlike neurons, astrocytes could maintain low level of SOX2 expression after they acquired glial fate. Further studies are needed to determine whether differences in the level of SOX2 expression in GFAP-positive astrocytes are in correlation with their self-renewal capacity, differentiation status, and/or their phenotypic characteristics.
    Biochemistry (Moscow) 11/2014; 79(11):1172-82. · 1.35 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Analysis of the kinetic and stochastic models describing the dynamics of the core gene network for maintenance of pluripotency and differentiation of embryonic stem cells is represented. The core gene network was modified according to the latest experimental data on the regulation of Nanog expression. Analysis of the kinetic model showed that in the dynamics of the concentration changes as Nanog mRNA and protein could potentially exist oscillating mode, which may explains the experimentally observed Nanog heterogeneity in stem cell populations. Stochastic approach, in turn, allowed us to reveal a range of parameters, in which there are two possible system states as the result of stochastic fluctuations: the high and low levels of expression of Oct4, Sox2 and Nanog. It is possible to accidentally switch from one state to another that may also be one of the mechanisms of the Nanog heterogeneity.
    Mathematical Biology and Bioinformatics. 12/2014; 9(2):504-517.


Available from