○Hyeyoung A. Chung1,2 Junko H. Miura1 Chie Terasaka1 Atsushi Kitayama1 Naoto Ueno1
Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology1，Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo2
The question of how an embryo forms fully organized tissues has been fundamental issue
during early embryogenesis. In Xenopus, it is known that coordinated movements of cells during
gastrulation conduct the primary body plan.
Members of FGF family are involved in formation and
specification of mesoderm in the early stages of development. Interestingly, embryos expressing dominant-
negative form of FGF receptor, XFD, showed phenotypes of not only defective mesoderm but also the
failure of cell migration during gastrulation and the posterior truncation. The zygotic expression of FGFs is
in the blastopore region and they may play roles in processes other than mesoderm induction.
SU5402
is a highly specific chemical inhibitor of FGFR and embryos exposed to SU5402 showed central depressed
cavity and incomplete closure of the blastopore. Inhibition of elongation was observed in Keller explants
treated with SU5402 and these phenotypes were very similar to those of XFD injected embryos. To identify
FGF target genes, gene expression profile of Keller explants cultured with or without SU5402 was analyzed
using NIBB non-redundant 4.6K microarray. Through microarray analysis we have isolated 39 clones down-
regulated (ratio<2) and 5 clones up-regulated (ratio>2) by SU5402 exposure from stage 10.5 to 11.5. These
clones included transcription factor, scaffolding protein, kinase, and cell adhesion molecule. Further step of
screening with whole-mount in situ hybridization was carried out. Possible function of genes of our
interest will be discussed.
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