Mothers against dpp participates in a DDP/TGF-beta responsive serine-threonine kinase signal transduction cascade.
Mothers against dpp (Mad) is the prototype of a family of genes required for signaling by TGF-beta related ligands. In Drosophila, Mad is specifically required in cells responding to Decapentaplegic (DPP) signals. We further specify the role of Mad in DPP-mediated signaling by utilizing tkvQ199D, an activated form of the DPP type I receptor serine-threonine kinase thick veins (tkv). In the embryonic midgut, tkvQ199D mimics DPP-mediated inductive interactions. Homozygous Mad mutations block signaling by tkvQ199D. Appropriate responses to signaling by tkvQ199D are restored by expression of MAD protein in DPP-target cells. Endogenous MAD is phosphorylated in a ligand-dependent manner in Drosophila cell culture. DPP overexpression in the embryonic midgut induces MAD nuclear accumulation; after withdrawal of the overexpressed DPP signal, MAD is detected only in the cytoplasm. However, in three different tissues and developmental stages actively responding to endogenous DPP, MAD protein is detected in the cytoplasm but not in the nucleus. From these observations, we discuss possible roles for MAD in a DPP-dependent serine-threonine kinase signal transduction cascade integral to the proper interpretation of DPP signals.
Newfeld
S J
SJ
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Mehra
A
A
Singer
M A
MA
Wrana
J L
JL
Attisano
L
L
Gelbart
W M
WM
D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004064:Digestive System / Q000737:chemistry / Q000196:embryology; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology*; D004707:Endoderm; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D008024:Ligands; D008648:Mesoderm; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors; D016212:Transforming Growth Factor beta / Q000235:genetics
D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D008024:Ligands; C112506:MAD protein, Drosophila; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C064196:dpp protein, Drosophila; C090169:tkv protein, Drosophila; D017346:Protein Serine-Threonine Kinases