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Dev Biol March 1, 2008; 315 (1): 161-72.
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Long- and short-range signals control the dynamic expression of an animal hemisphere-specific gene in Xenopus.

Mir A , Kofron M , Heasman J , Mogle M , Lang S , Birsoy B , Wylie C .

Little is known of the control of gene expression in the animal hemisphere of the Xenopus embryo. Here we show that expression of FoxI1e, a gene essential for normal ectoderm formation, is expressed regionally within the animal hemisphere, in a highly dynamic fashion. In situ hybridization shows that FoxI1e is expressed in a wave-like fashion that is initiated on the dorsal side of the animal hemisphere, extends across to the ventral side by the mid-gastrula stage, and is then turned off in the dorsal ectoderm, the neural plate, at the neurula stage. It is confined to the inner layers of cells in the animal cap, and is expressed in a mosaic fashion throughout. We show that this dynamic pattern of expression is controlled by both short- and long-range signals. Notch signaling controls both the mosaic, and dorsal/ventral changes in expression, and is controlled, in turn, by Vg1 signaling from the vegetal mass. FoxI1e expression is also regulated by nodal signaling downstream of VegT. Canonical Wnt signaling contributes only to late changes in the FoxI1e expression pattern. These results provide new insights into the roles of vegetally localized mRNAs in controlling zygotic genes expressed in the animal hemisphere by long-range signaling. They also provide novel insights into the role of Notch signaling at the earliest stages of vertebrate development.

PubMed ID: 18234171
PMC ID: PMC2323448
Article link: Dev Biol
Grant support: [+]

Species referenced: Xenopus
Genes referenced: bmp4 cat.2 ctnnb1 foxi1 foxl1 gal.2 gdf1 hes5.1 nodal nodal1 nodal3.1 nodal3.2 nog notch1 odc1 sia1 vegt
GO keywords: Notch signaling pathway
Morpholinos: ctnnb1 MO1 vegt MO7

Article Images: [+] show captions
References [+] :
Abe, Activin-like signaling activates Notch signaling during mesodermal induction. 2004, Pubmed, Xenbase