Direct and indirect regulation of derrière, a Xenopus mesoderm-inducing factor, by VegT.

One candidate for an endogenous mesoderm-inducing factor in Xenopus is derrière, a member of the TGFbeta family closely related to Vg1. In this paper we first show that derrière is able to exert long-range effects in the early Xenopus embryo, reinforcing the view that it functions as a secreted factor required for proper formation of posterior structures. Analysis of the derrière promoter shows that expression of the gene is controlled through a complex inductive network involving VegT and TGFbeta-related molecules and also, perhaps, FGF family members. The work confirms that derrière plays an important role in mesoderm formation and it illustrates the complex regulation to which inducing factors are subject.