Proc Natl Acad Sci U S A
January 17, 2006;
Xbves is a regulator of epithelial movement during early Xenopus laevis development.
/pop1a is a unique, highly conserved integral membrane protein expressed in embryonic epithelia and striated muscle
. Although studies have proposed a role in epithelial morphogenesis, the function of Bves
/pop1a in development is completely unknown. Here we show that Xenopus laevis Bves
) RNA and protein are expressed in epithelia of the early embryo
. Transfection of Xbves
into nonadherent mouse L cells confers cell/cell adhesion. Global inhibition of Xbves
function by morpholino injection into two-cell embryos arrests development at gastrulation by deregulating the epithelial movements of epiboly and involution. Clonal inhibition of Xbves
activity within the A1 blastomere
and its derivatives completely randomizes movement of its progeny within otherwise normally differentiating embryos. These data demonstrate that Bves
/pop1a proteins play a critical role in epithelial morphogenesis and, specifically, in the cell movements essential for epithelial rearrangements that occur during X. laevis development.
Proc Natl Acad Sci U S A
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Fig. 1. Whole-mount in situ hybridization analysis of Xbves expression. A four-cell embryo is seen from the animal (A) and vegetal (B) poles and from the lateral side (C). A 16-cell embryo is seen from the animal (D) and vegetal (E) poles and from the lateral side (F). Xbves expression is observed in the surface epithelium in gastrulation stage embryos but is excluded from the yolk plug (G and H) and a more restrictive dorsal expression pattern in neurulation stage (I). Lateral view, dorsal view, and ventral view of embryos at stages 20 (J–L) and 25 (M and N) demonstrates Xbves distribution. Xbves expression in the heart (white arrow), eye (black arrow), cement gland, and somites of a stage 35 embryo (O). Control sense probe hybridization of four-cell (P), stage 11.5 (Q), and stage 35 embryos (R) are negative.
Fig. 2. Immunohistochemical analysis of Xbves expression in early embryos. (A) At stage 11.5, anti-Xbves (green) reacts with surface and involuted cells but is negative for endodermal cells of the yolk plug (YP). (B) High power view of region outlined by the box in A. Arrows show that Xbves is confined to regions of cell/cell contact and is missing from the apical regions of the cell. (B′) High power view of stage 8 embryos shows similar distribution of Xbves protein. (C) Anti-Xbves reacts with ectodermal and mesodermal tissues of the stage 19 embryo. The neural tube (NT), eye (E), and surface ectoderm (arrows) are specific epithelial structures labeled by this serum. The white box, magnified in C, shows staining of the notochord. (D) Xbves expression is detected at the cell surface of mesodermally derived notochord.
Andrée, Isolation and characterization of the novel popeye gene family expressed in skeletal muscle and heart. 2000, Pubmed