Nodal and Planar Cell Polarity signaling cooperate to regulate zebrafish convergence and extension gastrulation movements

During vertebrate gastrulation, convergence & extension (C&E) of the primary anteroposterior (AP) embryonic axis is driven by polarized mediolateral (ML) cell intercalations and is influenced by AP axial patterning. Nodal signaling is essential for patterning of the AP axis while Planar Cell Polarity (PCP) signaling polarizes cells with respect to this axis, but how these two signaling systems interact during C&E is unclear. We find that the neuroectoderm of Nodal-deficient zebrafish gastrulae exhibits reduced C&E cell behaviors, which require Nodal signaling in both cell- and non-autonomous fashions. PCP signaling is partially active in Nodal-deficient embryos and its inhibition exacerbates their C&E defects. Within otherwise naïve zebrafish blastoderm explants, however, Nodal induces C&E in a largely PCP-dependent manner, arguing that Nodal acts both upstream of and in parallel with PCP during gastrulation to cooperatively regulate embryonic axis extension.