A novel mesoderm inducer, Madr2, functions in the activin signal transduction pathway.

摘要: A functional assay to clone mouse mesoderm inducers has identified the gene Mad related 2 (Madr2). Madr2 induces dorsal from Xenopus ectoderm and can mimic organizer in recruiting neighboring cells into a second axis. By analyzing expression of lacZ/Madr2 fusion protein, we find confined nucleus deep, anterior axis, whereas epidermal more posterior protein is cytoplasmically localized. This context-dependent nuclear localization suggests that certain regions embryo, responds localized signal amplifies this form Furthermore, although remains unlocalized ectodermal explants, addition activin enhances concentration nucleus. Significantly, lacZ carboxy-terminal portion even absence activin. indicates contains domain activate downstream components repressive anchors cytoplasm. Nuclear response activin, activin-like phenotypes induced by overexpression Madr2, indicate transduction component mediates activity