OAZ Uses Distinct DNA- and Protein-Binding Zinc Fingers in Separate BMP-Smad and Olf Signaling Pathways

We have identified the 30-zinc finger protein OAZ as a DNA-binding factor that associates with Smads in response to BMP2, forming a complex that transcriptionally activates the homeobox regulator of Xenopus mesoderm and neural development, Xvent-2. OAZ contains a BMP signaling module formed by two clusters of fingers that bind Smads and the Xvent-2 BMP response element, respectively. Previously implicated as a transcriptional partner of Olf-1/EBF in olfactory epithelium and lymphocyte development in the rat, OAZ fulfills this role through clusters of fingers that are separate from the BMP signaling module. The mutually exclusive use of OAZ by the BMP-Smad and Olf pathways illustrates the dual role of a multi–zinc finger protein in signal transduction during development.