Paraxis regulate the cell rearrangement during somite formation in Xenopus laevis embryogenesis.

SÁNCHEZ R.S.; MÓNACO M.E.; SÁNCHEZ S.S.

San Miguel de Tucumán, Tucumán, Argentina

Congreso; XLV Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB); 2009

SAIB

In all vertebrates the Paraxial Mesoderm (PM) segmentation involves the formation of metameric units called somites through a Mesenchymal-Epithelial Transition. However this morphogenetic process is different in the amphibian Xenopus laevis because it does not form an epithelial somite, it rather undergoes a complex cell rearrangement. The molecular mechanisms that control these cell behaviours underlying somite formation remain elusive. Paraxis is a bHLH transcription factor expressed in vertebrate PM and in the somite. To establish the role of paraxis in this model organism, we carried out experiments of gain and loss of function by using a hormone-inducible construct. We found that the knockdown of this gene resulted in a delay in the development timing and morphogenetic movements, defects in the somite formation and a reduction in the expression of somitic molecular markers. These results suggest that paraxis could play an important role in Presomitic-Somitic Mesoderm Transition. We also showed that non-canonical Wnt signalling pathway would be responsible of paraxis expression regulation through CaM Kinase II during X. laevis development.