First published online October 12, 2007
Development 134, 2102e (2007)
© The Company of Biologists Limited
Found: earliest known specifier of the trophectoderm
Specification in mammalian embryos begins in the 16-cell morula with the
emergence of the trophectoderm (TE, from which the placenta develops) and the
inner cell mass (ICM, from which the embryo develops). Now, on
p. 3827, Yagi and
colleagues report that the transcription factor TEAD4 specifies the TE lineage
at the start of mammalian development. The researchers show that
Tead4, like the highly homologous Tead2 gene, is first
expressed in the mouse two-cell embryo. Tead4-/- embryos
develop to the morula stage, they report, but do not express TE-specific genes
nor establish a TE lineage, and die before blastocyst formation and
implantation. Tead2-/- embryos, by contrast, develop into
viable adults. Tead4-/- embryos do, however, express
ICM-specific genes and can produce embryonic stem cells, derivatives of the
ICM. Furthermore, if Tead4 is only disrupted after implantation,
Tead4-/- embryos complete development. Thus, the
researchers conclude, Tead4 is the earliest known TE lineage
specifier, the expression of which, during zygotic gene activation, triggers
the eventual differentiation of totipotent blastomeres into TE.
Related articles in Development:
- Transcription factor TEAD4 specifies the trophectoderm lineage at the beginning of mammalian development
- Rieko Yagi, Matthew J. Kohn, Irina Karavanova, Kotaro J. Kaneko, Detlef Vullhorst, Melvin L. DePamphilis, and Andres Buonanno
Development 2007 134: 3827-3836.
[Abstract]
[Full Text]