title: IQGAP2 is required for the cadherin-mediated cell-to-cell adhesion in Xenopus laevis embryos.
abstract: We have previously identified two Xenopus homologues of mammalian IQGAP, XIQGAP1 and XIQGAP2, which show high homology with human IQGAP1 and IQGAP2, respectively. In order to clarify function of the IQGAPs during development, we performed knock-down experiments on the XIQGAPs in Xenopus laevis embryos by microinjecting morpholino antisense oligonucleotides into blastomeres at the two-cell stage. Suppression of XIQGAP2 expression caused ectodermal lesions in the neurula stage embryos. While suppression of XIQGAP1 expression alone did not show any obvious defect in subsequent developmental processes, simultaneous knock-down of both XIQGAPs caused the ectodermal lesions during the gastrula stage. Histological studies suggested that a loss of cell adhesion in the ectodermal and mesodermal layers of the embryos caused the defect. The suppression of XIQGAP2 expression resulted in loss of actin filaments, beta-catenin, and XIQGAP1 from cell borders in the ectoderm, although it did not affect the expression levels of these proteins. Furthermore, it inhibited Ca(2+)-induced reaggregation of embryonic cells which had been dissociated in a Ca(2+)/Mg(2+)-free medium. These results strongly suggest that XIQGAP2 is crucial for cell adhesion during early development in Xenopus.
authors.affiliation: Division of Biology, Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Sawako
authors.initials: S
authors.lastname: Yamashiro
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Abe
authors.forename: Issei
authors.initials: I
authors.lastname: Mabuchi
mesh_terms: D000818:Animals; D001483:Base Sequence; D015820:Cadherins / Q000502:physiology*; D002448:Cell Adhesion / Q000502:physiology*; D018076:DNA, Complementary / Q000235:genetics; D020690:GTPase-Activating Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000502:physiology*; D051176:beta Catenin / Q000378:metabolism; D020703:ras GTPase-Activating Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology
chemical_list: D015820:Cadherins; D018076:DNA, Complementary; D020690:GTPase-Activating Proteins; C101203:IQ motif containing GTPase activating protein 1; C484415:IQGAP2 protein, Xenopus; D020319:Oligodeoxyribonucleotides, Antisense; D029867:Xenopus Proteins; D051176:beta Catenin; D020703:ras GTPase-Activating Proteins