Human embryonic stem cells (hES) are unique in their pluripotency and capacity for self-renewal. Therefore, we have studied the differences in the level of chromatin condensation in pluripotent and all-trans retinoic acid-differentiated hES cells. Nuclear patterns of the Oct4 (6p21.33) gene, responsible for hES cell pluripotency, the C-myc (8q24.21) gene, which controls cell cycle progression, and HP1 protein (heterochromatin protein 1) were investigated in these cells. Unlike differentiated hES cells, pluripotent hES cell populations were characterized by a high level of decondensation for the territories of both chromosomes 6 (HSA6) and 8 (HSA8). The Oct4 genes were located on greatly extended chromatin loops in pluripotent hES cell nuclei, outside their respective chromosome territories. However, this phenomenon was not observed for the Oct4 gene in differentiated hES cells, for the C-myc gene in the cell types studied. The high level of chromatin decondensation in hES cells also influenced the nuclear distribution of all the variants of HP1 protein, particularly HP1 alpha, which did not form distinct foci, as usually observed in most other cell types. Our experiments showed that unlike C-myc, the Oct4 gene and HP1 proteins undergo a high level of decondensation in hES cells. Therefore, these structures seem to be primarily responsible for hES cell pluripotency due to their accessibility to regulatory molecules. Differentiated hES cells were characterized by a significantly different nuclear arrangement of the structures studied.

Laboratory of Molecular Cytology Cytometry Institute of Biophysics Academy of Sciences of the Czech Republic Královopolská 135 612 65 Brno Czech Republic

References provided by Crossref.org

The SC-35 Splicing Factor Interacts with RNA Pol II and A-Type Lamin Depletion Weakens This Interaction

A role of the 53BP1 protein in genome protection: structural and functional characteristics of 53BP1-dependent DNA repair

The Role of RNA Polymerase II Contiguity and Long-Range Interactions in the Regulation of Gene Expression in Human Pluripotent Stem Cells

PRMT1 arginine methyltransferase accumulates in cytoplasmic bodies that respond to selective inhibition and DNA damage

Epigenetics and chromatin plasticity in embryonic stem cells

Differentiation-independent fluctuation of pluripotency-related transcription factors and other epigenetic markers in embryonic stem cell colonies

Recruitment of Oct4 protein to UV-damaged chromatin in embryonic stem cells

Heterogeneity in the kinetics of nuclear proteins and trajectories of substructures associated with heterochromatin

Structure and epigenetics of nucleoli in comparison with non-nucleolar compartments

Histone modifications and nuclear architecture: a review

Single-cell c-myc gene expression in relationship to nuclear domains

Positioning of NORs and NOR-bearing chromosomes in relation to nucleoli