title: The involvement of Eph-Ephrin signaling in tissue separation and convergence during Xenopus gastrulation movements.
abstract: In Xenopus gastrulation, the involuting mesodermal and non-involuting ectodermal cells remain separated from each other, undergoing convergent extension. Here, we show that Eph-ephrin signaling is crucial for the tissue separation and convergence during gastrulation. The loss of EphA4 function results in aberrant gastrulation movements, which are due to selective inhibition of tissue constriction and separation. At the cellular levels, knockdown of EphA4 impairs polarization and migratory activity of gastrulating cells but not specification of their fates. Importantly, rescue experiments demonstrate that EphA4 controls tissue separation via RhoA GTPase in parallel to Fz7 and PAPC signaling. In addition, we show that EphA4 and its putative ligand, ephrin-A1 are expressed in a complementary manner in the involuting mesodermal and non-involuting ectodermal layers of early gastrulae, respectively. Depletion of ephrin-A1 also abrogates tissue separation behaviors. Therefore, these results suggest that Eph receptor and its ephrin ligand might mediate repulsive interaction for tissue separation and convergence during early Xenopus gastrulation movements.
authors.affiliation: Division of Molecular and Life Sciences, Pohang University of Science and Technology, Nam-gu, Pohang, Kyungbuk, Republic of Korea.
authors.forename: Edmond Changkyun
authors.initials: EC
authors.lastname: Park
authors.forename: Gun-Sik
authors.initials: GS
authors.lastname: Cho
authors.forename: Gun-Hwa
authors.initials: GH
authors.lastname: Kim
authors.forename: Sun-Cheol
authors.initials: SC
authors.lastname: Choi
authors.forename: Jin-Kwan
authors.initials: JK
authors.lastname: Han
mesh_terms: D000818:Animals; D015820:Cadherins / Q000502:physiology; D002465:Cell Movement; D016764:Cell Polarity; D036382:Ephrin-A1 / Q000502:physiology*; D054262:Gastrulation; D000091363:Protocadherins; D036122:Receptor, EphA4 / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins / Q000502:physiology; D020742:rhoA GTP-Binding Protein / Q000502:physiology
chemical_list: D015820:Cadherins; D036382:Ephrin-A1; C492040:Fzd7 protein, Xenopus; C117635:Pcdh8 protein, Xenopus; D000091363:Protocadherins; D043562:Receptors, G-Protein-Coupled; D029867:Xenopus Proteins; D036122:Receptor, EphA4; D020742:rhoA GTP-Binding Protein