Embryonic stem cells contribute to mouse chimeras in the absence of detectable cell fusion.

Embryonic stem (ES) cells are capable of differentiating into all embryonic and adult cell types following mouse chimera production. Although injection of diploid ES cells into tetraploid blastocysts suggests that tetraploid cells have a selective disadvantage in the developing embryo, tetraploid hybrid cells, formed by cell fusion between ES cells and somatic cells, have been reported to contribute to mouse chimeras. In addition, other examples of apparent stem cell plasticity have recently been shown to be the result of cell fusion.

The TGF beta activated kinase TAK1 regulates vascular development in vivo.

TGFbeta activated kinase 1 (TAK1) is a MAPKKK that in cell culture systems has been shown to act downstream of a variety of signaling molecules, including TGFbeta. Its role during vertebrate development, however, has not been examined by true loss-of-function studies. In this report, we describe the phenotype of mouse embryos in which the Tak1 gene has been inactivated by a genetrap insertion.

Efficient transfection of embryonic and adult stem cells.

The ability of embryonic stem cells and adult stem cells to differentiate into specific cell types holds immense potential for therapeutic use in cell and gene therapy. Realization of this potential depends on efficient and optimized protocols for genetic manipulation of stem cells. In the study reported here, we demonstrate the use of nucleofection as a method to introduce plasmid DNA into embryonic and adult stem cells with significantly greater efficiency than electroporation or lipid-based transfection methods have.

Expression of TAK1, a mediator of TGF-beta and BMP signaling, during mouse embryonic development.

TGF-beta activated kinase 1 (TAK1) is a MAP kinase kinase kinase (MAPKKK) that has been shown to function downstream of BMPs and TGF-beta (J. Biol. Chem.