A Prospective Dominant Negative Mutant of Wnt Signaling In Zebrafish Causes Craniofacial Asymmetry with Low Penetrance

Abstract

Wnt gene signaling pathways have been implicated in development, cell behavior, and diseases, including craniofacial abnormalities. We created mutant complementary DNA constructs using QuikChange mutagenesis and then compared them to wild-type cDNA for effects on zebrafish development following injection into one-cell embryos. We hypothesized that disrupting a putative Wnt-binding lipocalin motif would allow mutant tinagl1 mRNAs to induce a dominant negative phenotype, similar to tinagl1 gene knockdown. Mutant LCN-W2 but not WT mRNA preferentially gave small eyes and ventral body curvature similar to the gene knockdown. Our main focus was on craniofacial development using Alcian blue staining of cartilage elements in 5 day old zebrafish. Abnormalities were seen at low penetrance in high-survival (high-quality) clutches with the highest injected dose of TIN LCN-W2,150 pg. These included smaller head and asymmetric head skeleton with one smaller eye on side of variable cartilage defects. Craniofacial defects, especially asymmetry, were more prevalent in clutches with lower survival rates. These asymmetric defects had not been seen in the gene knockdown. In summary, the phenotypes of LCN-W2 partially support similarity to a dominant negative phenotype with cartilage defects, small eyes, and ventrally curved body, but the craniofacial asymmetry appears novel. More research is needed for further understanding.