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Development 2006 Dec 01;13323:4643-54. doi: 10.1242/dev.02657.
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Shisa2 promotes the maturation of somitic precursors and transition to the segmental fate in Xenopus embryos.

Nagano T , Takehara S , Takahashi M , Aizawa S , Yamamoto A .

In vertebrate somitogenesis, FGF and Wnt signals constitute a morphogenetic gradient that controls the maturation of the presomitic mesoderm (PSM) as well as the transition to segmental units. It remains unclear, however, whether there is a regulatory mechanism that promotes the transition by a direct regulation of FGF and Wnt signaling in the PSM. Here we show that Shisa2, a member of a novel Shisa gene family, plays an essential role in segmental patterning during Xenopus somitogenesis. Shisa2 encodes an endoplasmic reticulum (ER) protein that cell-autonomously inhibits FGF and Wnt signaling by preventing the maturation and the cell-surface expression of their receptors. Shisa2 is expressed in the PSM and its knockdown caused a reduction in somite number by the delayed maturation of PSM and anterior shift of the transition; however, the phase of the segmental clock remained intact. These phenotypes were abolished by the inhibition of both FGF and Wnt signals, but by neither alone. We therefore propose that the individual inhibition of both types of signaling by the regulation of receptor maturation in the ER plays an essential role in the establishment of proper segmental patterning.

PubMed ID: 17065233
Article link: Development

Species referenced: Xenopus
Genes referenced: acss2.1 aldh1a2 axin2l calr chrd clock cyp26a1 fgf2 fgf8 fzd8 gsk3b hes5.7 hes6.1 lfng lrp6 mapk1 msgn1 myod1 nkd1 nodal3.1 otx2 pcdh8 pcdh8.2 rarg shisa1 shisa2 shisa3 snai1 tbx2 tbxt thy1 wif1 wnt3a wnt8a
Morpholinos: shisa2 MO1 shisa2 MO2 shisa2 MO3

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