title: Inhibition of FGF signaling converts dorsal mesoderm to ventral mesoderm in early Xenopus embryos.
abstract: In early vertebrate development, mesoderm induction is a crucial event regulated by several factors including the activin, BMP and FGF signaling pathways. While the requirement of FGF in Nodal/activin-induced mesoderm formation has been reported, the fate of the tissue modulated by these signals is not fully understood. Here, we examined the fate of tissues when exogenous activin was added and FGF signaling was inhibited in animal cap explants of Xenopus embryos. Activin-induced dorsal mesoderm was converted to ventral mesoderm by inhibition of FGF signaling. We also found that inhibiting FGF signaling in the dorsal marginal zone, in vegetal-animal cap conjugates or in the presence of the activin signaling component Smad2, converted dorsal mesoderm to ventral mesoderm. The expression and promoter activities of a BMP responsive molecule, PV.1 and a Spemann organizer, noggin, were investigated while FGF signaling was inhibited. PV.1 expression increased, while noggin decreased. In addition, inhibiting BMP-4 signaling abolished ventral mesoderm formation induced by exogenous activin and FGF inhibition. Taken together, these results suggest that the formation of dorso-ventral mesoderm in early Xenopus embryos is regulated by a combination of FGF, activin and BMP signaling.
authors.affiliation: Department of Biochemistry, College of Medicine, Hallym University, ChunCheon, Kangwon-Do, 200-702, Republic of Korea.
authors.forename: Sung-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Soo-Kyung
authors.initials: SK
authors.lastname: Lim
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Cha
authors.forename: Jaeho
authors.initials: J
authors.lastname: Yoon
authors.forename: Seung-Hwan
authors.initials: SH
authors.lastname: Lee
authors.forename: Hyun-Shik
authors.initials: HS
authors.lastname: Lee
authors.forename: Jae-Bong
authors.initials: JB
authors.lastname: Park
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Sung Chan
authors.initials: SC
authors.lastname: Kim
authors.forename: Jaebong
authors.initials: J
authors.lastname: Kim
mesh_terms: D028341:Activins / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D019521:Body Patterning; D055415:Bone Morphogenetic Protein 4 / Q000037:antagonists & inhibitors / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation; D005346:Fibroblast Growth Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism; D008648:Mesoderm / Q000196:embryology*; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics; D000099176:Noggin Protein
chemical_list: D028341:Activins; D055415:Bone Morphogenetic Protein 4; D002352:Carrier Proteins; D005346:Fibroblast Growth Factors; D018398:Homeodomain Proteins; D051899:Smad2 Protein; D029867:Xenopus Proteins; D000099176:Noggin Protein; C497782:SMAD2 protein, human; C525812:bmp4 protein, Xenopus; C109693:ventx1.1 protein, Xenopus