Core planar cell polarity function in migrating gastrula cells – analysis of a novel zebrafish prickle1a mutant line

Abstract

Planar cell polarity (PCP) is one of the many important events that occur during zebrafish gastrulation, playing a key role in cell movements that underlie convergence and extension (C&E) of the embryonic body axis. Identifying and understanding the driving forces of this phenomenon will provide further insight into the embryonic development of organisms. Previously, numerous studies performed in the fly have established a six-member core protein PCP pathway, however, many details regarding a core PCP pathway in vertebrates have yet to be elucidated. VANGL planar cell polarity protein 2 (Vangl2) is the zebrafish ortholog of the fly core PCP protein Van Gogh/Strabismus (Vang/Stbm) and has been established as a crucial component of zebrafish PCP. Nonetheless, it is still unclear whether other homologs of the fly core PCP proteins serve similar roles in higher vertebrate organisms, such as zebrafish. In this study, we evaluated Prickle1a, which is a zebrafish homolog to another core fly PCP protein (Prickle) that is known to interact with Vangl2. Using a previously generated nonsense prickle1a mutant (the sa24579 allele), we performed RT-PCR and microinjection of embryos with prickle1a mRNA and vangl2 antisense morpholino to genetically characterize this mutant. Furthermore, we evaluated the morphology, alignment, and directed migration of mediolateral mesodermal cells at the end of gastrulation (tailbud stage) through differential interference contrast microscopy. We also examined defects in the body axis and C&E visualized in live and fixed whole embryos. While the genetic characterization of this mutation is still not fully understood, we did determine that PCP in the prickle1a sa24579 mutant is interrupted, suggesting that the Prickle1a protein is involved in zebrafish PCP.