Genomic organization and modulation of gene expression of the TGF-β and FGF pathways in the allotetraploid frog Xenopus laevis.
Inductive interactions mediated by the TGF-β and FGF-MAPK pathways are essential for specification of the germ layers and embryonic body axes during early vertebrate embryogenesis. TGF-β and FGF ligands signal through receptor Ser/Thr and Tyr kinases, respectively, and these signaling pathways cross-talk to regulate transcription and cell behavior. The allotetraploid Xenopus laevis and its ancestral diploid Xenopus tropicalis are versatile model organisms with which to study the inductive interactions and mechanisms of these signal transduction pathways. Here we have analyzed the draft genome of X. laevis with respect to the genomic organization and differential expression of genes in the TGF-β and FGF pathways. Genomic structure and gene expression analyses of pathway components in X. laevis revealed that genetic modulations, including deletions resulting in singletons and differential expression of homeologs, have occurred frequently among extracellular regulatory factors of the TGF-β pathway after allotetraploidization. Moreover, differential gene expression was found for factors regulating various cellular responses including co-receptors, decoy receptors, and intracellular negative regulators in both the TGF-β and FGF-MAPK pathways. We summarize the patterns of genetic alterations in the allotetraploid frog X. laevis and discuss the importance of these changes with regard to developmental processes.
Amphibian Research Center, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan. Electronic address: asuzuki@hiroshima-u.ac.jp.
Atsushi
A
Suzuki
Amphibian Research Center, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
Hitoshi
H
Yoshida
Department of Molecular Developmental Biology, Radboud University, Faculty of Science, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, Nijmegen, The Netherlands.
Simon J
SJ
van Heeringen
Amphibian Research Center, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
Kimiko
K
Takebayashi-Suzuki
Department of Molecular Developmental Biology, Radboud University, Faculty of Science, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, Nijmegen, The Netherlands.
Gert Jan C
GJC
Veenstra
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Masanori
M
Taira
D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning / Q000235:genetics; D004171:Diploidy; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004627:Embryonic Induction / Q000235:genetics*; D044127:Epigenesis, Genetic; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D049810:Genetic Speciation; D023281:Genomics; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000235:genetics; D058977:Molecular Sequence Annotation; D017978:Receptors, Growth Factor / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics*; D051785:Smad Proteins / Q000378:metabolism; D057891:Tetraploidy; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus / Q000235:genetics; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000235:genetics* / Q000378:metabolism
D008024:Ligands; D017978:Receptors, Growth Factor; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; D005346:Fibroblast Growth Factors
Allotetraploidy; FGF; Genomic structure; TGF-β; Xenopus