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The pluripotency factor Oct4 interacts with Ctcf and also controls X-chromosome pairing and counting
Mary E Donohoe1, Susana S Silva, Stefan F Pinter
1Howard Hughes Medical Institute, USA.
Nature
|June 19, 2009
Summary
Oct4, a key pluripotency factor, initiates X-chromosome inactivation (XCI) by regulating homologous chromosome pairing and counting. This discovery reveals Oct4
Area of Science:
- Epigenetics and Gene Regulation
- Stem Cell Biology
- Genomics and Chromosome Biology
Background:
- Embryonic stem (ES) cell pluripotency is governed by transcription factors.
- X-chromosome inactivation (XCI) silences one female X chromosome during differentiation for gene dosage.
- XCI involves homologous chromosome pairing, counting, and random choice, tightly linked to cell differentiation.
Purpose of the Study:
- To elucidate the interconnection between pluripotency factors and X-chromosome inactivation (XCI).
- To identify the role of Oct4 in regulating XCI.
- To understand how Oct4 influences X-chromosome pairing and counting.
Main Methods:
- Investigated the binding of Oct4 to regulatory noncoding RNA genes (Tsix and Xite) at the X-inactivation centre.
- Examined protein-protein interactions between Oct4 and XCI trans-factors (Ctcf and Yy1).
- Assessed the impact of Oct4 depletion on homologous X-chromosome pairing and XCI in female cells.
Main Results:
- Oct4 directly binds to Tsix and Xite, key regulators of XCI.
- Oct4 forms complexes with Ctcf and Yy1, essential for XCI.
- Oct4 depletion abrogates homologous X-chromosome pairing and leads to biallelic X chromosome inactivation.
Conclusions:
- Oct4 is identified as a master regulator at the top of the XCI hierarchy.
- Oct4 triggers homologous X-chromosome pairing and counting, essential for proper XCI.
- This study assigns novel functions to Oct4 in X-chromosome reprogramming and epigenetic regulation.
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