Abstract

The centrosome is the primary microtubule organizing center (MTOC) of most animal cells. However, preimplantation mouse embryos only establish centrosomes at the late blastocyst stage. Therefore, the mechanism by which the early mammalian embryo organizes its microtubules (MTs) is unclear. By imaging fluorescently labeled MTs in live mouse embryos using four-dimensional confocal (4D) microscopy, we recently discovered a non-centrosomal form of MT organization in the early embryo. We find that contrary to most animal cells, the cytokinetic bridge does not undergo stereotypical abscission after cell division in the developing mouse embryo. Instead, it serves as a scaffold for the accumulation of proteins that stabilize MT minus ends and promote MT outgrowth throughout interphase, thereby transforming this structure into a non-centrosomal MTOC. Moreover, we show that this MTOC directs the transport of proteins such as E-cadherin to the cell membrane, which are essential to establish the first forms of tissue architecture during development. Together, our findings reveal how MTs are organized and function during the early stages of mammalian embryogenesis.

Special Speaker – Jennifer Zenker flyer (PDF)