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Dev Cell July 1, 2004; 7 (1): 95-106.

Xenopus XsalF: anterior neuroectodermal specification by attenuating cellular responsiveness to Wnt signaling.

Onai T , Sasai N , Matsui M , Sasai Y .

Here we show that XsalF, a frog homolog of the Drosophila homeotic selector spalt, plays an essential role for the forebrain/midbrain determination in Xenopus. XsalF overexpression expands the domain of forebrain/midbrain genes and suppresses midbrain/hindbrain boundary (MHB) markers and anterior hindbrain genes. Loss-of-function studies show that XsalF is essential for the expression of the forebrain/midbrain genes and for the repression of the caudal genes. Interestingly, XsalF functions by antagonizing canonical Wnt signaling, which promotes caudalization of neural tissues. XsalF is required for anterior-specific expressions of GSK3beta and Tcf3, genes encoding antagonistic effectors of Wnt signaling. Loss-of-function phenotypes of GSK3beta and Tcf3 mimic those of XsalF while injections of GSK3beta and Tcf3 rescue loss-of-function phenotypes of XsalF. These findings suggest that the forebrain/midbrain-specific gene XsalF negatively controls cellular responsiveness to posteriorizing Wnt signals by regulating region-specific GSK3beta and Tcf3 expression.

PubMed ID: 15239957
Article link: Dev Cell

Species referenced: Xenopus
Genes referenced: ag1 chdh chrd.1 en2 foxg1 gbx2.1 gbx2.2 gsk3b mafb myod1 otx2 pax2 pax6 sall2 snai2 tcf3 tcf7l1 wnt1
Morpholinos: gsk3b MO1 sall2 MO1 sall2 MO2 tcf7l1 MO4

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