| First Author | Zuccotti M | Year | 2002 |
| Journal | Mol Reprod Dev | Volume | 61 |
| Issue | 1 | Pages | 14-20 |
| PubMed ID | 11774371 | Mgi Jnum | J:73471 |
| Mgi Id | MGI:2155528 | Doi | 10.1002/mrd.1126 |
| Citation | Zuccotti M, et al. (2002) Mouse Xist expression begins at zygotic genome activation and is timed by a zygotic clock. Mol Reprod Dev 61(1):14-20 |
| abstractText | The imprinted mouse Xist (X-inactive specific transcript) gene is involved in the initiation of X-chromosome inactivation. Only the paternal Xist is expressed in preimplantation development beginning from the 4-cell stage, preceding and in correlation with paternal X-inactivation in the extraembryonic lineage of the blastocyst. To better understand the mechanisms regulating Xist expression in early development, we investigated the precise timing of its onset. We set up a single-cell RT-PCR for the simultaneous analysis on single embryos of Xist and Hprt (internal control) cDNAs and a Y-chromosome specific DNA sequence, Zfy (for embryo sexing). Applying this procedure, we demonstrate that Xist expression begins at the G2-phase of 2-cell female embryos, earlier than previously reported and at the same time of the major wave of zygotic genome activation (ZGA). We then examined, if Xist expression at the 2-cell stage is dependent on the lapse of time spent since fertilization, as previously reported for zygotic genes. One-cell embryos at the G2-phase of the first cell-cycle were cultured with cytochalasin D (inhibitor of cytokinesis but not of DNA synthesis or nuclear progression) for a time equivalent to the 4-cell stage in control, untreated embryos. We show that Xist activation occurs at a scheduled time following fertilization despite the embryos being blocked at the 1-cell stage, suggesting the existence of a zygotic clock involved in the regulation of the transcription of this imprinted gene. |
