NE enhancer activation and notochord development in transgenic mouse embryos. Furthermore, manipulation of Tead activity in zebrafish embryos led to altered expression of foxa2 in the embryonic shield. These results suggest that Tead activates the Foxa2 enhancer core element in the mouse node in cooperation with a second factor that binds to the 5Ј Ј element, and that a similar mechanism also operates in the zebrafish shield.
Research articleDevelopment 4720 led to the identification of an evolutionarily conserved sequence motif, CS3, which is essential for enhancer activity (Nishizaki et al., 2001). Here, we identified the Tead family transcription factors as proteins that bind to CS3. Tead family transcription factors all contain a DNA-binding domain called a TEA domain, and consist of four members (Tead1-Tead4) in both mouse and human (Jacquemin et al., 1998;Kaneko and DePamphilis, 1998). The founding member of this family, Tead1 [also known as transcriptional enhancer factor 1 (TEF-1)], was originally identified as an activator of simian virus 40 (SV40) enhancer (Davidson et al., 1988;Xiao et al., 1991). A Drosophila Tead protein, Scalloped (Sd), interacts with a co-activator protein, Vestigial (Vg), and regulates wing development (Halder et al., 1998;Simmonds et al., 1998). Vertebrate Tead proteins also require co-factors to act as activators, and the candidates are the four Vg homologs (Maeda et al., 2002;Vaudin et al., 1999) and Yes-associated protein 65 (YAP65) (Maeda et al., 2002;Vassilev et al., 2001;Vaudin et al., 1999). Several other mechanisms are also suggested for regulation of Tead activity, including interaction with other transcription factors and modification by protein kinases (Gupta et al., 2001; Gupta et al., 1997;Jiang et al., 2001;Thompson et al., 2003). Tead genes are expressed widely, from preimplantation embryos to various adult tissues, with distinct patterns (Jacquemin et al., 1998;Kaneko et al., 1997). Tead proteins are suggested to be involved in activation of the cardiac and skeletal muscle genes, CTP:phosphocholine cytidylyltransferase (Pcyt -Mouse Genome Informatics) and Pax3 in neural crest cells (Jiang et al., 2000; Milewski et al., 2004;Stewart et al., 1994;Sugimoto et al., 2001), and Tead1 mutant embryos die between E11 and 12 due to resulting heart defects (Chen et al., 1994). However, the roles played by Tead genes during early embryogenesis have not yet been revealed.In this study, we first showed that the core element (CE) of the Foxa2 enhancer drives gene expression in the node. Two transcription factors activate the CE in a cooperative fashion, and Tead proteins are one of these factors. The Tead-binding site in the CE was essential for node/notochord enhancer (NE) activity, and inhibition of Tead function in mouse embryos disturbed notochord development. In zebrafish embryos, manipulation of Tead activity changed the expression of foxa2. These results suggest that the key mechanism of Foxa2 expression in the node/notochord is activation of the enhancer core element ...