Functional Characterization Of Grb10 During The Early Embryonic Development Of Xenopus

Vertebrate body column is established during gastrulation. Several signaling pathways have been implicated in regulating cell polarity and cell movements during gastrulation, among which Wnt/PCP (planar cell polarity) signaling plays an important role. Grb7/10/14 family proteins are multi-domain containing adaptors that have been widely linked to receptor tyrosine kinase signals, including insulin pathway. However, their roles during early embryogenesis are largely unknown. Here we report the identification and functional characterization of Xenopus grb10. In Xenopus embryos, grb10 is maternally distributed and strongly expressed in ectoderm and mesoderm cells in gastrulae. At neural stage, it is widely expressed in various tissues including the central nerve system and somites. Gain and loss-of-function experiments demonstrate that grb10 is directly involved in regulating gastrulation movements. In dorsal mesoderm cells, up- or down-regulating grb10 impairs cell polarity formation and convergent extension. At molecular level, it likely functions by affecting Wnt/PCP signaling and acts epistatically downstream of Dishevelled. The results of this project have provided evidences supporting a previously unidentified role of grb10 gene in early embryonic development.