The distribution of Dishevelled in convergently extending mesoderm

Abstract

Convergent extension (CE) is a conserved morphogenetic movement that drives axial lengthening of the primary body axis and depends on the planar cell polarity (PCP) pathway. In Drosophila epithelia, a polarised subcellular accumulation of PCP core components, such as Dishevelled (Dvl) protein, is associated with PCP function. Dvl has long been thought to accumulate in the mediolateral protrusions in Xenopus chordamesoderm cells undergoing CE. Here we present a quantitative analysis of Dvl intracellular localisation in Xenopus chordamesoderm cells. We find that, surprisingly, accumulations previously observed at mediolateral protrusions of chordamesodermal cells are not protrusion-specific but reflect yolk-free cytoplasm and are quantitatively matched by the distribution of the cytoplasm-filling lineage marker dextran. However, separating cell cortex-associated from bulk Dvl signal reveals a statistical enrichment of Dvl in notochord–somite boundary-(NSB)-directed protrusions, which is dependent upon NSB proximity. Dvl puncta were also observed, but only upon elevated overexpression. These puncta showed no statistically significant spatial bias, in contrast to the strongly posteriorly-enriched GFP-Dvl puncta previously reported in zebrafish. We propose that Dvl distribution is more subtle and dynamic than previously appreciated and that in vertebrate mesoderm it reflects processes other than protrusion as such.

PI4K2β constrains non-canonical Wnt-PCP signalling and is localised by PAR-1 (MARK2/3) phosphorylation

“…Co-injection of the two constructs interfered with expression of both, a phenomenon we have observed with other proteins 45 . However, injection of GFP-PI4K2β wild type and mCherry-PI4K2β SA mutant into nearby parts of same embryo highlighted that GFP-PI4K2β wild type is more basolaterally localised than the mCherry-PI4K2β SA mutant ( Fig.5F-F").…”

Dynamic intracellular distribution of Vangl2 during cell polarization in zebrafish gastrula

“…Similar to the asymmetric distribution of the core PCP components in Drosophila epithelia, asymmetric localization of core PCP proteins expressed as fluorescent fusion proteins was observed in mediolaterally polarized cells during zebrafish gastrulation, with Pk-GFP and Dvl-GFP fusion proteins being enriched at the anterior and posterior cell membranes, respectively (Ciruna et al, 2006;Yin et al, 2008). By contrast, in Xenopus Dvl is enriched at the cell edges facing the notochord-somite boundary (Panousopoulou et al, 2013). Yet, C&E movements in Xenopus explants are controlled by PCP core proteins via the Septin cytoskeleton and its ability to regulate cortical actomyosin compartmentalization and the remodeling of cell-cell contacts (Shindo and Wallingford, 2014).…”

Planar cell polarity in moving cells: think globally, act locally

“…Live imaging of mesodermal cells in Xenopus, zebrafish and mouse embryos shows that perturbation of PCP signaling disrupts mediolateral polarity and stability of mesodermal cell protrusions, their mediolateral alignment and elongation, and the polarization of both the medial and radial intercalations that normally serve to narrow and extend the AP axis (Table 1) (Darken et al, 2002;Heisenberg et al, 2000;Jessen et al, 2002;Takeuchi et al, 2003;Veeman et al, 2003;Wallingford et al, 2000;Yen et al, 2009;Yin et al, 2008). Although Dvl was initially reported to localize to mediolateral protrusions, where it was thought to promote actin polymerization (Kinoshita et al, 2003), this was subsequently found to be illusory (Panousopoulou et al, 2013). Instead, work in zebrafish has identified a more classically planar polarized distribution of PCP proteins in mediolaterally elongated mesodermal cells during CE (Fig.…”