High impact information on Xdsh

• Here we show, using time-lapse confocal microscopy, that the failure of cells lacking Xdsh function to undergo convergent extension results from defects in cell polarity [1].
• Here we show that Xenopus Dishevelled (Xdsh) interacts with a Xenopus Axin-related protein (XARP) [2].
• Finally, our data point to a possible mechanism for signal transduction, in which Xdsh prevents beta-catenin degradation by displacing GSK3 from its complex with XARP [2].
• Moreover, the same domains are essential for signal transduction through Xdsh [2].
• Remarkably, although inhibition of Xdsh signaling disrupted both convergent extension and blastopore closure, mesendoderm internalization proceeded very effectively in these embryos [3].

Biological context of Xdsh

• We present evidence that ephrinB1 signals through its intracellular domain to control retinal progenitor movement into the eye field by interacting with Xenopus Dishevelled (Xdsh), and by using the planar cell polarity (PCP) pathway [4].
• These studies suggest that Wnt signal transduction pathway is conserved between Drosophila and vertebrates and point to a role for maternal Xdsh product in dorsal axis formation and in neural induction [5].
• Dorsal expression of Xdd1 caused severe posterior truncations in the injected embryos, whereas wild-type Xdsh suppressed this phenotype [6].

Anatomical context of Xdsh

• In contrast to its effect on mesoderm, overexpression of Xdsh mRNA in prospective ectodermal cells triggers anterior neural tissue differentiation [5].
• Overexpression of Xdd1 mRNA in ventral blastomeres of Xenopus embryos strongly inhibited induction of secondary axes by the wild-type Xdsh and Xwnt8 mRNAs, but did not affect the axis-inducing ability of beta-catenin mRNA [6].
• At the highest dose of Xdsh mRNA, explants contained maximal amount of HoxB9 transcripts and developed notochord and somites [7].

Other interactions of Xdsh

• Analysis of explants overexpressing Xdsh at the gastrula stage revealed activation of several organizer-specific genes which have been implicated in determination of neural tissue (Xotx2, noggin, chordin and follistatin) [7].
• Secondly, we examined the effects of four Wnt-pathway-interfering constructs (dominant-negative Xdsh, XGSK3, Axin, and dominant-negative XTcf3) on the ability of VCC to induce expression of the early Wnt target genes, Siamois and Xnr3 [8].
• To assess the effect of Xenopus Dishevelled (Xdsh), a proposed component of the Wnt, Notch and Frizzled signal transduction pathways, on AP axis determination, it was supplied in varying doses to presumptive ectodermal cells [7].
• Lower doses of Xdsh mRNA activated anterior neuroectodermal markers, XAG1 and Xotx2, whereas the higher doses induced more posterior neural tissue markers such as En2, Krox20 and HoxB9 [7].

References