PCP protein segregation to opposite cell sides is reinforced by reciprocal intracellular repulsion and extracellular stabilization of core complexes ( Aw and Devenport, 2017 Fisher and Strutt, 2019 Peng and Axelrod, 2012), but an initial cue is needed to define the orientation of the polarity vector relative to the body axes. These core proteins are part of a signaling pathway that regulates cell shape and motility through the action of multiple effectors, including components of the vesicular trafficking machinery and cytoskeleton-remodeling factors ( Butler and Wallingford, 2017 Devenport, 2014). Both PCP complexes also include the atypical cadherin Flamingo (Celsr in vertebrates). The core PCP pathway, initially identified in Drosophila, comprises two protein complexes: Frizzled/Dishevelled and Prickle/Van Gogh (Vangl in vertebrates) that segregate to opposite cell borders ( Devenport, 2014 Goodrich and Strutt, 2011 Vladar et al., 2009). Genetic studies have implicated PCP components in many morphogenetic processes, including vertebrate neurulation, lung and kidney development and left–right patterning, and mutations in PCP genes have been linked to birth defects in humans ( Goodrich and Strutt, 2011 Gray et al., 2011 Nikolopoulou et al., 2017 Tian et al., 2020). The coordinated polarization of neighboring cells in the plane of the tissue is known as planar cell polarity (PCP). These observations suggest that neuroectodermal PCP is not instructed by a preexisting molecular gradient but induced by a signal from the dorsal blastopore lip.ĭuring morphogenesis, collective cell behaviors may be orchestrated in a multicellular organism through the integration of individual polarities of constituent cells. The PCP cue did not depend on the orientation of the graft and was distinct from neural inducers. Tissue transplantations indicated that PCP is triggered in the neural plate by a planar cue from the dorsal blastopore lip. By imaging Vangl2 and Prickle3, we show that PCP is progressively acquired in the neural plate and requires a signal from the posterior region of the embryo. Here we investigate the Xenopus neural plate, a tissue that has been previously shown to exhibit PCP. Although the segregation of PCP components to opposite cell borders is believed to play a critical role in this pathway, whether PCP derives from egg polarity or preexistent long-range gradient, or forms in response to a localized cue, remains a challenging question. Coordinated polarization of cells in the tissue plane, known as planar cell polarity (PCP), is associated with a signaling pathway critical for the control of morphogenetic processes.
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