Biomedical subjects

Yayoi Toyooka

Publications and source records attributed to Yayoi Toyooka.

3 recordsLinked to original sources

PubMed2005

Interaction between Oct3/4 and Cdx2 determines trophectoderm differentiation.

Trophectoderm (TE), the first differentiated cell lineage of mammalian embryogenesis, forms the placenta, a structure unique to mammalian development. The differentiation of TE is a hallmark event in early mammalian development, but molecular mechanisms underlying this first differentiation event remain obscure. Embryonic stem (ES) cells can be induced to differentiate into the TE lineage by forced repression of the POU-family transcription factor, Oct3/4. We show here that this event can be mimicked by overexpression of Caudal-related homeobox 2 (Cdx2), which is sufficient to generate proper trophoblast stem (TS) cells. Cdx2 is dispensable for trophectoderm differentiation induced by Oct3/4 repression but essential for TS cell self-renewal. In preimplantation embryos, Cdx2 is initially coexpressed with Oct3/4 and they form a complex for the reciprocal repression of their target genes in ES cells. This suggests that reciprocal inhibition between lineage-specific transcription factors might be involved in the first differentiation event of mammalian development.

Animals↗

PubMed2005

An efficient system to establish multiple embryonic stem cell lines carrying an inducible expression unit.

The growing use of mouse embryonic stem (ES) cells in research emphasizes their importance in studies of molecular mechanisms that maintain pluripotency and direct cellular differentiation. Although systems for regulatable transgene expression are essential for fine analysis of cellular processes at the molecular level, a strategy for the establishment of multiple ES cell lines carrying any of these systems has not yet been described. Here, we report our development of the ROSA-TET system, an effective system for the establishment of multiple ES cell lines carrying a tetracycline (Tc)-regulatable transgene at the Gt (ROSA)26asSor (ROSA26) locus. This system contains a knock-in step of a construct carrying both loxP and its mutant sequences into the ROSA26 locus, followed by a subsequent exchange step that introduces a cDNA to be Tc-regulated to the locus using the recombinase-mediated cassette exchange reaction. Both steps are demonstrated to give desired clones with high efficiency, suggesting that this system can be introduced readily into any ES cell lines, leading to the simultaneous establishment of multiple cell lines carrying different Tc-regulated cDNAs. We believe that use of this system will strongly accelerate molecular biological research using ES cells.

Animals↗

PubMed2003

Embryonic stem cells can form germ cells in vitro.

Knock-in embryonic stem (ES) cells, in which GFP or lacZ was expressed from the endogenous mouse vasa homolog (Mvh), which is specifically expressed in differentiating germ cells, were used to visualize germ cell production during in vitro differentiation. The appearance of MVH-positive germ cells depended on embryoid body formation and was greatly enhanced by the inductive effects of bone morphogenic protein 4-producing cells. The ES-derived MVH-positive cells could participate in spermatogenesis when transplanted into reconstituted testicular tubules, demonstrating that ES cells can produce functional germ cells in vitro. In vitro germ cell differentiation provides a paradigm for studying the molecular basis of germ line establishment, as well as for developing new approaches to reproductive engineering.

3T3 Cells↗