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- Title
Evidence that homologous X-chromosome pairing requires transcription and Ctcf protein.
- Authors
Na Xu; Donohoe, Mary E.; Silva, Susana S.; Lee, Jeannie T.
- Abstract
X-chromosome inactivation (XCI) ensures the equality of X-chromosome dosages in male and female mammals by silencing one X in the female. To achieve the mutually exclusive designation of active X (Xa) and inactive X (Xi), the process necessitates that two Xs communicate in trans through homologous pairing. Pairing depends on a 15-kb region within the genes Tsix and Xite. Here, we dissect molecular requirements and find that pairing can be recapitulated by 1- to 2-kb subfragments of Tsix or Xite with little sequence similarity. However, a common denominator among them is the presence of the protein Ctcf, a chromatin insulator that we find to be essential for pairing. By contrast, the Ctcf-interacting partner, Yy1 (ref. 8), is not required. Pairing also depends on transcription. Transcriptional inhibition prevents new pair formation but does not perturb existing pairs. The kinetics suggest a pairing half-life of <1 h. We propose that pairing requires Ctcf binding and co-transcriptional activity of Tsix and Xite.
- Publication
Nature Genetics, 2007, Vol 39, Issue 11, p1390
- ISSN
1061-4036
- Publication type
Academic Journal
- DOI
10.1038/ng.2007.5