Journal Article

The macrosatellite DXZ4 mediates CTCF-dependent long-range intrachromosomal interactions on the human inactive X chromosome

Andrea H. Horakova, Shawn C. Moseley, Christine R. McLaughlin, Deanna C. Tremblay and Brian P. Chadwick

in Human Molecular Genetics

Volume 21, issue 20, pages 4367-4377
Published in print October 2012 | ISSN: 0964-6906
Published online July 2012 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/dds270
The macrosatellite DXZ4 mediates CTCF-dependent long-range intrachromosomal interactions on the human inactive X chromosome

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The human X-linked macrosatellite DXZ4 is a large tandem repeat located at Xq23 that is packaged into heterochromatin on the male X chromosome and female active X chromosome and, in response to X chromosome, inactivation is organized into euchromatin bound by the insulator protein CCCTC-binding factor (CTCF) on the inactive X chromosome (Xi). The purpose served by this unusual epigenetic regulation is unclear, but suggests a Xi-specific gain of function for DXZ4. Other less extensive bands of euchromatin can be observed on the Xi, but the identity of the underlying DNA sequences is unknown. Here, we report the identification of two novel human X-linked tandem repeats, located 58 Mb proximal and 16 Mb distal to the macrosatellite DXZ4. Both tandem repeats are entirely contained within the transcriptional unit of novel spliced transcripts. Like DXZ4, the tandem repeats are packaged into Xi-specific CTCF-bound euchromatin. These sequences undergo frequent CTCF-dependent interactions with DXZ4 on the Xi, implicating DXZ4 as an epigenetically regulated Xi-specific structural element and providing the first putative functional attribute of a macrosatellite in the human genome.

Journal Article.  6152 words.  Illustrated.

Subjects: Genetics and Genomics

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