The genetics and the molecular functions of the PREP1 homeodomain transcription factor.

Prep1 (pKnox1) is a homeodomain transcription factor of the TALE superclass whose members can act as co-factors of Hox. Prep1 is essential for embryogenesis, but in the adult it also acts as a tumor suppressor. We describe and analyze here the available mutant mice, their phenotypes and a few discordant cases. Moreover we specify the basic rules underlying the binding of Prep1 and its TALE partners to DNA, and their plasticity during embryonic development. We finally review recent data on Prep1 which indicate a very basic cellular function at the level of DNA replication and DNA damage.