Don’t assume that two identical-looking cells are the same…they may both be rounded and cute, but there is a lot of exciting stuff brewing inside. A recent paper describes the use of a clever microscopy technique to look at how subtle differences in a transcription factor’s kinetics can predict early patterning in the mouse embryo.
There has always been debate and discussion about when the differences that lead to lineage patterning first appear in the cells of very early embryos. Although cells in the very early mouse embryo appear morphologically identical, a recent paper describes the different kinetics of one transcription factor in different cells in the mouse embryo. To measure these differences, Plachta and colleagues tagged the transcription factor Oct4 with a special fluorescent marker that is activated by a certain wavelength of light. Once this marker was activated in certain cells in the 4- and 8-cell embryo, the movement of Oct4 into and out of the nucleus (where it does its job by binding to DNA) was monitored. One group of cells had slower rates of export and import and was more likely to give rise to the inner cell mass, while the second group had higher rates and was more likely to give rise to the extra-embryonic lineage. Image shows an 8-cell embryo with the Oct4 marker activated (green) in the nucleus of one specific cell.
Plachta, N., Bollenbach, T., Pease, S., Fraser, S., & Pantazis, P. (2011). Oct4 kinetics predict cell lineage patterning in the early mammalian embryo Nature Cell Biology, 13 (2), 117-123 DOI: 10.1038/ncb2154
Adapted by permission from Macmillan Publishers Ltd, copyright 2011