Rsx is a metatherian RNA with Xist-like properties in X-chromosome inactivation

Jennifer Grant, Shantha K. Mahadevaiah, Pavel Khil, Mahesh N. Sangrithi, Hélène Royo, Janine Duckworth, John R. McCarrey, John L. Vandeberg, Marilyn B. Renfree, Willie Taylor, Greg Elgar, R. Daniel Camerini-Otero, Mike J. Gilchrist, James M.A. Turner

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


In female (XX) mammals, one of the two X chromosomes is inactivated to ensure an equal dose of X-linked genes with males (XY). X-chromosome inactivation in eutherian mammals is mediated by the non-coding RNA Xist. Xist is not found in metatherians (marsupials), and how X-chromosome inactivation is initiated in these mammals has been the subject of speculation for decades. Using the marsupial Monodelphis domestica, here we identify Rsx (RNA-on-the-silent X), an RNA that has properties consistent with a role in X-chromosome inactivation. Rsx is a large, repeat-rich RNA that is expressed only in females and is transcribed from, and coats, the inactive X chromosome. In female germ cells, in which both X chromosomes are active, Rsx is silenced, linking Rsx expression to X-chromosome inactivation and reactivation. Integration of an Rsx transgene on an autosome in mouse embryonic stem cells leads to gene silencing in cis. Our findings permit comparative studies of X-chromosome inactivation in mammals and pose questions about the mechanisms by which X-chromosome inactivation is achieved in eutherians.

Original languageEnglish (US)
Pages (from-to)254-258
Number of pages5
Issue number7406
StatePublished - Jul 12 2012
Externally publishedYes

ASJC Scopus subject areas

  • General


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