An activated form of type I serine/threonine kinase receptor TARAM-A reveals a specific signalling pathway involved in fish head organiser formation.
The role of Transforming Growth Factor beta (TGF-beta)-related molecules in axis formation and mesoderm patterning in vertebrates has been extensively documented, but the identity and mechanisms of action of the endogenous molecules remained uncertain. In this study, we isolate a novel serine/threonine kinase type I receptor, TARAM-A, expressed during early zebrafish embryogenesis first ubiquitously and then restricted to dorsal mesoderm during gastrulation. A constitutive form of the receptor is able to induce the most anterior dorsal mesoderm rapidly and to confer an anterior organizing activity. By contrast, the wild-type form is only able to induce a local expansion of the dorsal mesoderm. Thus an activated form of TARAM-A is sufficient to induce dorsoanterior structures and TARAM-A may be activated by dorsally localized signals. Our data suggest the existence in fish of a specific TGF-beta-related pathway for anterior dorsal mesoderm induction, possibly mediated by TARAM-A and activated at the late blastula stage by localized dorsal determinant.
Renucci
A
A
U 368 Inserm, ENS, Paris.
Lemarchandel
V
V
Rosa
F
F
D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004627:Embryonic Induction / Q000235:genetics*; D006257:Head / Q000196:embryology; D008648:Mesoderm / Q000502:physiology; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D015027:Zebrafish / Q000196:embryology
D018076:DNA, Complementary; D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases