The zinc finger gene Xblimp1 controls anterior endomesodermal cell fate inSpemann's organizer

The anterior endomesoderm of the early Xenopus gastrula is a part of Speman n's organizer and is important for head induction. Here we describe Xblimp1 , which encodes a zinc finger transcriptional repressor expressed in the an terior endomesoderm. Xblimp1 represses trunk mesoderm and induces anterior endomesoderm in a cooperative manner with the pan-endodermal gene Mix. I. F urthermore, Xblimp1 can cooperate with the BMP inhibitor chordin to induce ectopic heads, while a dominant-negative Xblimp1 inhibits head formation. T he head inducer cerberus is positively regulated by Xblimp1 and is able to rescue microcephalic embryos caused by dominant-negative Xblimp1. Our resul ts indicate that Xblimp1 is required for anterior endomesodermal cell fate and head induction.