PDGF SIGNALING IS REQUIRED FOR GASTRULATION OF XENOPUS-LAEVIS

During Xenopus gastrulation, platelet-derived growth factor (PDGF) rec eptor-alpha is expressed in involuting marginal zone cells which migra te over ectodermal cells expressing PDGF-A, To investigate the role of PDGF signalling during this process, we have generated a novel point mutant of PDGF receptor-a analogous to the W-37 mutation of c-kit, Thi s molecule is a specific, potent, dominant inhibitor of PDGF signallin g in vivo, Injection of RNA encoding this protein into Xenopus embryos prevents closure of the blastopore, leads to abnormal gastrulation an d a loss of anterior structures, Convergent extension is not inhibited in these embryos, but rather, involuting mesodermal cells fail to adh ere to the overlying ectoderm, PDGF may therefore be required for meso dermal cell-substratum interaction.