Ectopic Pax-3 Activates MyoD and Myf-5 Expression in Embryonic Mesoderm and Neural Tissue

摘要: Summary induce myogenic precursors or to maintain and expand a population of already specified cells (see Munsterberg To understand how the skeletal muscle lineage is in- Lassar, 1995, references therein). We have duced during vertebrate embryogenesis, we shown that myogenesis explanted presegmental sought identify regulatory molecules medi- plate mesoderm (isolated from stage 10 chick embryo) ate induction factors MyoD requires two signals axial tissues, one emanating Myf-5. In this work, demonstrate either floor plate-notochord complex other overlying ectoderm Wnt Sonic more dorsal regions neural tube (Mun- hedgehog can somitic expression sterberg 1995). Consistent with these find- paired box transcription factors, Pax-3 Pax-7, ings, Emerson colleagues recently reported concomitant Myf-5 prior notochord are required initiate quail MyoD. Moreover, infection embryonic tissues in vitro retrovirus encoding sufficient ovo (Pow- MyoD, Myf-5, myogenin nall et al., 1996). both paraxial lateral ab- The muscle-promoting signal plate- sence inducing as well tube. be mimicked by signaling Together, findings imply may mediate molecule (Shh), muscle-pro- activation response muscle- moting overly- cell lines programmed express Wnt-1 Wnt-3 ing key regulator (Munsterberg 1995; Stern Because myogenesis.