Dynamic intracellular distribution of Vangl2 during cell polarization in zebrafish gastrula

Abstract

During vertebrate gastrulation, convergence and extension movements elongate embryonic tissues anteroposteriorly and narrow them mediolaterally. Planar cell polarity (PCP) signaling is essential for mediolateral cell elongation underlying these movements, but how this polarity arises is poorly understood. We analyzed the elongation, orientation and migration behaviors of lateral mesodermal cells undergoing convergence and extension movements in wild-type zebrafish embryos and mutants for the Wnt/PCP core component Vangl2 (Trilobite). We demonstrate that Vangl2 function is required at the time when cells transition to a highly elongated and mediolaterally aligned body. vangl2 mutant cells fail to undergo this transition and to migrate along a straight path with high net speed towards the dorsal midline. Instead, vangl2 mutant cells exhibit an anterior/animal pole bias in cell body alignment and movement direction, suggesting that PCP signaling promotes effective dorsal migration in part by suppressing anterior/ animalward cell polarity and movement. Endogenous Vangl2 protein accumulates at the plasma membrane of mesenchymal converging cells at the time its function is required for mediolaterally polarized cell behavior. Heterochronic cell transplantations demonstrated that Vangl2 cell membrane accumulation is stage dependent and regulated by both intrinsic factors and an extracellular signal, which is distinct from PCP signaling or other gastrulation regulators, including BMP and Nodals. Moreover, mosaic expression of fusion proteins revealed enrichment of Vangl2 at the anterior cell edges of highly mediolaterally elongated cells. These results demonstrate that the dynamic Vangl2 intracellular distribution is coordinated with and necessary for the changes in convergence and extension cell behaviors during gastrulation.

Planar cell polarity in development and disease

“…While the asymmetric localization of PCP components is well-established in D. melanogaster wing, the control of core PCP localization during convergent extension remains poorly defined. However, predominant features of the system appear to be conserved, as PK and VANGL were described to localize anteriorly in cells undergoing convergent extension, while DVL was shown to localize posteriorly 78–82 .…”

“…Most evidence suggests that the PCP proteins form complementary asymmetric zones of localization on the anterior and posterior cell faces during convergent extension 78–82 (Fig. 5c).…”

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

“…Pk and Vangl localize together at the level of AJs on anterior membranes in the frog neural plate (Ossipova et al, 2015b). In the fish, in which maturation of the apical surface of neuroepithelial progenitors is delayed (Araya et al, 2016), Pk and Vangl2 localize asymmetrically to the anterior side of immature progenitors (Ciruna et al, 2006;Roszko et al, 2015) and are subsequently recruited to anterior AJs (Davey et al, 2016). The Flamingo homolog Celsr1 localizes to both anterior and posterior AJs, a localization that is particularly apparent when cells become aligned along the mediolateral axis of the chick neural plate (Nishimura et al, 2012) (Fig.…”

“…3): Pk is detected in dynamic puncta that preferentially localize to anterior membranes, whereas Dvl puncta localize to posterior membranes (Ciruna et al, 2006;Yin et al, 2008). Vangl2 also localizes to anterior membranes and is required for anterior Pk localization (Roszko et al, 2015;Yin et al, 2008). Aside from their failure to elongate and align along the mediolateral axis, Vangl2 mutant mesodermal cells display an aberrant tendency to migrate anteriorly during gastrulation, suggesting that Vangl2 at the anterior membrane normally resists this directional bias (Roszko et al, 2015).…”

“…Vangl2 also localizes to anterior membranes and is required for anterior Pk localization (Roszko et al, 2015;Yin et al, 2008). Aside from their failure to elongate and align along the mediolateral axis, Vangl2 mutant mesodermal cells display an aberrant tendency to migrate anteriorly during gastrulation, suggesting that Vangl2 at the anterior membrane normally resists this directional bias (Roszko et al, 2015). This could explain, at least in part, the most striking cell migration defect reported for vangl2 mutant cells: more convoluted trajectories during dorsal convergence compared with those observed in wild-type cells (Jessen et al, 2002).…”