The Control of Germ Cell Migration in the Embryo; a “Migrating Niche” for Migrating Stem Cells.
Stem cell populations in the body are surrounded by “niches” of specialized cells that control stem cell behavior, including the property of pluripotency. Stem cells are released from their niches in a controled fashion to differentiate into the specialized tissues of the body. In the embryo, several stem cell populations migrate through the tissues of the embryo to occupy their final positions where a niche is established. How their behaviors are controled during migration, when there is no niche, is not known, and is an important gap in our knowledge of control of stem cell behavior.
In the mouse, primordial germ cells, which give rise to all the gametes of the animal, arise during gastrulation, and migrate through the developing tissues of the embryo to colonize the gonad primordia. Preliminary data, and published work from our lab shows that from the time of their first appearance, germ cells are surrounded by cells expressing Steel factor, a signaling ligand previously shown to be essential for germ cell survival. We propose that Steel factor-expressing cells represent a “travelling niche” for the germ cells while they are migrating, and this project sets out to test this hypothesis. First we will test whether the close-range action of Steel factor is controled by the expression of Steel factor in membrane-bound form by the surrounding cells. Second will seek to identify the mechanism whereby Steel factor expression in initiated in the cells surrounding the germ cells, since the concept of a continuous niche around the germ cells during migration requires a mechanism for its establishment.
For movies of germ cell migration in the early mouse embryo, CLICK HERE: Germ Cell Movies
