The detailed entries of the Imprinted Gene Catalogue database were created by Benjamin Tycko, Columbia University, New York and are updated by Ian Morison


 

Detailed entry for Gene:

Xist
(and Tsix)

Chromosome:

Human ChrX
Mouse ChrX

Links:

OMIM  MethDB (mouse)

Imprinting:

The maternal allele of Xist is repressed; paternal allele active, in placenta (Ariel M et al, 1995; Kay GF et al, 1994; Norris DP et al, 1994; Zuccotti M et al, 1995). The inactivation of the entire X-chromosome shows a marked parent-of-origin dependence in the trophectoderm of mice, such that the paternal X is preferentially inactivated. This phenomenon, which does not occur in humans, may be a consequence of the imprinting of Xist, and/or its oppositely imprinted antisense transcript, Tsix (Lee JT, 2000; Sado T et al, 2001), in trophectoderm cells. In contrast, X-inactivation is (usually) a random process in human placenta and in other tissues.

Gene Product:

Xist encodes a non-translated RNA, which is expressed from and binds to ("coats") the inactive-X chromosome (Jaenisch R et al, 1998).

Functional Data:

Knockout experiments indicate that Xist is necessary for X-inactivation in ES cells and in mice (Marahrens Y et al, 1997; Penny GD et al, 1996). In addition, Xist transgenes can mediate changes at autosomal integration sites that resemble X-inactivation (Lee JT et al, 1996).

 

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