Format

Send to

Choose Destination
See comment in PubMed Commons below
Hum Mol Genet. 1997 Aug;6(8):1323-7.

XIST expression from the maternal X chromosome in human male preimplantation embryos at the blastocyst stage.

Author information

  • 1Institute of Obstetrics and Gynaecology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.

Abstract

In the somatic cells of female mammals, either the maternally or paternally derived X chromosome (X(M) or X(P)) is randomly inactivated to achieve dosage compensation for X-linked genes. In early mouse development, however, selective inactivation of X(P) occurs first in extraembryonic lineages at the blastocyst stage around the time of implantation before later random inactivation in the embryonic ectoderm from which the fetus is derived. Xist, a gene mapping to the X-inactivation centre (Xic), is exclusively expressed from the inactive X-chromosome and is thought to be involved in the initiation of X-inactivation. Consistent with this, Xist is first expressed at the 4-to 8-cell stages, prior to functional inactivation at the blastocyst stage, exclusively from X(P) in female embryos. This also suggests that genomic imprinting may influence the earliest expression of Xist resulting in selective inactivation of X(P) and a candidate methylation site in the promoter region has recently been described. Here we report the expression of the human homologue, XIST, in human preimplantation embryos from the 5- to 10-cell stage onwards consistent with its role in the initiation of inactivation. In contrast to the mouse, however, transcripts were detected in both male and female embryos demonstrating XIST expression from the X(M) in male embryos (X(M)Y).

PMID:
9259279
[PubMed - indexed for MEDLINE]
Free full text
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk