Michel Cohen-Tannoudji

The emergence of discrete cell identities from undifferentiated precursor cells is a central process in development and tissue homeostasis and repair, that when defective is at the basis of many human conditions including cancer and aging. The goal of our research is to provide a better understanding of the regulations operating at the levels of both intrinsic programs and extrinsic cues to ensure acquisition and maintenance of cell identities in an in vivo context. We are using as a model of choice the mouse preimplantation embryo, for which in vivo cell fate decisions can be scrutinized with high spatiotemporal resolution thus allowing to probe how dynamic changes in spatial cues and gene expression program are resolved into distinct cell identities in the intact embryo. In mammals, placental viviparity imposes on embryo development to begin with the generation of extraembryonic lineages required to interact with the maternal tissues, namely trophectoderm (TE) and primitive endoderm (PrE), while preserving a small population of pluripotent epiblast (Epi) cells from which the embryo proper originates. Understanding how these three lineages are produced in the proportion and arrangement appropriate for post-implantation development to proceed is of paramount importance in the context of the continuous decline of human fertility and increasing use of medically assisted reproductive technologies.