Xenopus Mad proteins transduce distinct subsets of signals for the TGF beta superfamily.
Xenopus cDNAs homologous to the Drosophila Mad gene and C. elegans CEM genes have been cloned and functionally analyzed by microinjection into frog embryos. The results show that these genes (Xmad) encode intracellular proteins that act downstream of TGF beta superfamily ligands. Most interesting is the fact that different Xmad proteins produce distinct biological responses. Xmad1 produces ventral mesoderm, apparently transducing a signal for BMP2 and BMP4, whereas Xmad2 induces dorsal mesoderm like Vg1, activin, and nodal. These results suggest that an individual Xmad protein waits poised in the cytoplasm for instruction from a distinct subset of TGF beta ligands and then conveys specific information to the nucleus.
Graff
J M
JM
Howard Hughes Medical Institute, Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Bansal
A
A
Melton
D A
DA
D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D008648:Mesoderm / Q000502:physiology; D008845:Microinjections; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology*; D051898:Smad1 Protein; D014157:Transcription Factors; D016212:Transforming Growth Factor beta / Q000502:physiology*; D014981:Xenopus / Q000235:genetics*; D029867:Xenopus Proteins
D004268:DNA-Binding Proteins; C499481:MADH1 protein, Xenopus; C499480:Mad2 protein, Xenopus; D012333:RNA, Messenger; D012097:Repressor Proteins; D051898:Smad1 Protein; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins