The functions of maternal Dishevelled 2 and 3 in the Early Xenopus embryo

Abstract

Of the three Dishevelled (Dvl) genes, only Dvl2 and Dvl3 are maternally encoded in the frog, Xenopus laevis. We show here by loss of function analysis that single depletion of either Dvl2 or Dvl3 from the oocyte causes the same embryonic phenotype. We find that the effects of loss of function of Dvl2 and 3 together are additive, and that the proteins physically interact, suggesting that both are required in the same complex. We show that maternal Dvl2 and 3 are required for convergence extension movements downstream of the dorsally localized signaling pathway activated by Xnr3, but not downstream of the pathway activated by activin. Also, depletion of maternal Dvl2 and 3 mRNAs causes the up-regulation of a subset of zygotic ectodermal genes, including Foxi1e, with surprisingly no significant effect on the canonical Wnt direct target genes Siamois and Xnr3. We suggest that the likely reason for continued expression of the Wnt target genes in Dvl2/3-depleted embryos is that maternal Dvl mRNA depletion is insufficient to deplete stored punctae of Dvl protein in the oocyte cortex, which may transduce dorsal signaling after fertilization.

Par6b Regulates the Dynamics of Apicobasal Polarity during Development of the Stratified Xenopus Epidermis

“…All RT-PCR results are presented as percentages compared with the levels in uninjected embryos after normalization to the expression of ornithine decarboxylase ( odc ). Embryos were cultured and processed for whole-mount ISH using a protocol described previously [51]. Sense and antisense par6b Dig-labeled RNA probes were synthesized using Ambion MEGA script kits and digoxygenin-11-UTP.…”

Insights into Molecular Features of Venerupis decussata Oocytes: A Microarray-Based Study

“…Ad hoc T-test (pval<0.05) demonstrated that a putative DVL3 transcript was higher in released oocytes, suggesting the importance of this molecule in bivalve oocyte maturation. The protein encoded by DVL3 gene is implicated in transduction signal ( Figure 3 ) conveyed by various WNT genes and, in Xenopus oocytes, its expression has been reported to be extremely important for transduction of canonical WNT signals after fertilization [62] . To conclude, the hypothesis that in V. decussata oocytes the amount of mRNAs encoding proteins involved in WNT signalling could be extremely important to complete oocyte maturation and fertilization is a matter of concern for future investigations.…”

Dishevelled Paralogs in Vertebrate Development: Redundant or Distinct?

“…However, DVL2 −/− DVL3 +/− and DVL1 −/− DVL2 −/− mice display much more severe NTD than DVL2 −/− mice (Hamblet et al, 2002; Wang et al, 2006; Etheridge et al, 2008), which strongly suggests that DVL1 and DVL3 contribute directly or indirectly to neural tube closure. Along this line, maternal single knock-down of either DVL2 or DVL3 in Xenopus caused NTD (Tadjuidje et al, 2011), supporting a contribution of DVL2 and DVL3.…”

“…In early Xenopus embryos, DVL2 and DVL3 are present maternally, whereas DVL1 expression is upregulated after the mid-blastula transition (Tadjuidje et al, 2011). At early gastrula stages, all three DVL paralogs are expressed in the prospective mesoderm including Spemann's organizer and, although weaker, in the ectoderm.…”