Van‐Gogh‐Like 2, Frizzled, and Knypek Control Distinct Aspects of Polarized Cellular Migration During Neural Convergence

• DOI: 10.1096/fasebj.31.1_supplement.1006.7
• Publication Date: 2021-06-08T00:29:23Z
• Authors: Karndeep Singh; Sharlene Brown; Jonathan Werner; Eudorah Vital; Stephanie Sanchez; Rebecca McFarland; Rachel Brewster
• Keywords: 0301 basic medicine; 03 medical and health sciences

The planar cell polarity (PCP) pathway plays a significant role in facilitating neural convergence (NC) – the narrowing of the neural plate before the formation of the neural tube. Evidence from the literature and our laboratory suggests that NC in zebrafish requires elongation and midline‐directed polarized migration of neural plate cells. Failure of NC or delayed stages of neural tube morphogenesis can result in severe neural tube defects (NTDs) which have been observed in all vertebrates studied. Although perturbation of the PCP pathway is associated with NTDs in model organisms and humans, the underlying neural cell behaviors remain elusive.In order to investigate the cellular effects of the PCP pathway, we used Knypek (Knyfr6), Van gogh‐like 2 (Vangl2vu67), and Frizzled 7a−/7b− (Fzd7ae3−; Fzd7bhu3495), three zebrafish lines carrying null mutations. We confirmed the published result that mutations in the PCP pathway delayed NC. We analyzed the width of the neural plate in 4–5 somite stage embryos to confirm NC by performing in situ hybridization using probes against the hindbrain and neural crest mRNAs Krox20 and Dlx3, respectively. Next, our comparative cellular analysis revealed how cell elongation, membrane dynamics, and trajectory are affected in homozygotes. We show that wild type (WT) neural plate cells elongate and medially restrict membrane protrusions, thus narrowing the neural tube. Our preliminary data show that cells in all mutants failed to elongate initially, specifically Vangl2 and Fzd7a/b mutant cells extend randomized protrusions while Kny mutant cells show temporally restricted protrusive activity. Furthermore, cell behavioral analysis revealed that neural plate cells in PCP mutant embryos are unable to polarize or migrate toward the midline effectively. Live cell behaviors were assessed by confocal fluorescence microscopy of embryos neural convergence extension movements.Evidence from the literature revealed that Kny is a Fzd co‐receptor thought to present Fzd with various Wnt ligands in the PCP pathway. Differences between Kny and Fzd7a/b cellular phenotypes could suggest a ligand‐independent aspect of PCP signaling during NC. While current literature understands that PCP genes regulate cell polarity and migration, the mechanisms of these genes in neural tissue and how they contribute to NTDs is poorly understood. By studying cell behaviors in the neural plate, our laboratory aims to further reveal how the PCP pathway promotes NC and identify additional genes affecting NTDs.Support or Funding InformationU.S. DOD W81XWH‐15‐RTR‐IDA NIH R01‐GM085290 NIH R03‐3HD076615 NSF DBI‐0722569 Meyerhoff Graduate Fellowship U.S. Department of Education GAANN Fellowship NIH/NIGMS MARC U*STAR T3408663 National Research Service Award to UMBC