Xenopus Rnd1 and Rnd3 GTP-binding proteins are expressed under the control of segmentation clock and required for somite formation.
The process of segmentation in vertebrates is described by a clock and wavefront model consisting of a Notch signal and an fibroblast growth factor-8 (FGF8) gradient, respectively. To further investigate the segmentation process, we screened gene expression profiles for downstream targets of the segmentation clock. The Rnd1 and Rnd3 GTP-binding proteins comprise a subgroup of the Rho GTPase family that show a specific expression pattern similar to the Notch signal component ESR5, suggesting an association between Rnd1/3 and the segmentation clock. Rnd1/3 expression patterns are disrupted by overexpression of dominant-negative or active forms of Notch signaling genes, and responds to the FGF inhibitor SU5402 by a posterior shift analogous to other segmentation-related genes, suggesting that Rnd1/3 expressions are regulated by the segmentation clock machinery. We also show that antisense morpholino oligonucleotides to Rnd1/3 inhibit somite segmentation and differentiation in Xenopus embryos. These results suggest that Rnd1/3 are required for Xenopus somitogenesis.
Division of Morphogenesis, National Institute for Basic Biology, Myodaiji, Okazaki, Japan. tg8j@cms.mail.virginia.edu
Tadahiro
T
Goda
Chiyo
C
Takagi
Naoto
N
Ueno
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000196:embryology* / Q000201:enzymology; D005346:Fibroblast Growth Factors / Q000037:antagonists & inhibitors / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D051880:Receptors, Notch / Q000378:metabolism*; D019170:Somites / Q000196:embryology* / Q000201:enzymology; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D016376:Oligonucleotides, Antisense; D011758:Pyrroles; D051880:Receptors, Notch; C491770:Rnd1 protein, Xenopus; C105686:SU 5402; D029867:Xenopus Proteins; D005346:Fibroblast Growth Factors; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins