Role of Foxa4a in dorsal axis development in Xenopus laevis

SABRINA MURGAN, CECILIA E. AGUIRRE, DIEGO R. REVINSKI, SILVIA L. LÓPEZ, ALEJANDRA R. PAGANELLI, ANDRÉS E. CARRASCO

Conferencia; 3rd South American Workshop & International Gregorio Weber Conference on New trends in Advanced Fluorescence Microscopy Techniques; 2011

The embryonic dorsal midline (DML), composed by the floor plate, the notochord and the hypochord, is known to play important roles in the patterning of dorsal tissues. In Xenopus laevis, FoxA4a encodes a winged-helix transcription factor expressed in the DML. Expression of FoxA4a begins very early, at late blastula, throughout the BCNE center. At later stages it is expressed in the Spemann’s organizer and its derivatives (floor plate, notochord and hypochord). Previous studies have shown that the ascidians FoxA4a homologue MocuFH1 is required for morphogenetic movements of the endoderm and notochord precursor cells during gastrulation and axis formation (Olsen and Jeffery, 1997). Besides it was reported that the mouse FoxA4a homologue FoxA2 has an essential role in the development of axial mesoderm (Ang and Rossant, 1994). The function exerted by FoxA4a in dorsal axis development in Xenopus embryos is still unknown. We have used whole-mount in situ hybridization and loss-of-function studies to investigate the involvement of FoxA4a in Xenopus dorsal axis development. We observe that knockdown of FoxA4a by antisense morpholino oligonucleotides results in defects of the DML. We show that the FoxA4a inhibition alters the notochord integrity and affects the expression of different markers in the neural axis. Our findings also indicate that blockage of FoxA4a impairs the morphogenetic movements, specially the convergent extension movements. We conclude that FoxA4a play a crucial role in the formation of the dorsal axis in Xenopus.