The involvement of Eph-Ephrin signaling in tissue separation and convergence during Xenopus gastrulation movements |
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Authors: | Park Edmond Changkyun Cho Gun-Sik Kim Gun-Hwa Choi Sun-Cheol Han Jin-Kwan |
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Institution: | aDivision of Molecular and Life Sciences, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Kyungbuk, 790-784, Republic of Korea;bDivision of Life Science, Korea Basic Science Institute, 52 Eoeun-dong, Yusung-gu, Daejeon, 305-333, Republic of Korea;cDepartment of Medicine, Graduate School, University of Ulsan, Pungnap-Dong, Songpa-Gu, Seoul 138-736, Republic of Korea |
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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. |
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Keywords: | EphA4 Ephrin-A1 Tissue separation CE movements Gastrulation Brachet's cleft Xenopus |
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