Ben, J., Elworthy, S., Ng, A.S., van Eeden, F., and Ingham, P.W. (2011) Targeted mutation of the talpid3 gene in zebrafish reveals its conserved requirement for ciliogenesis and Hedgehog signalling across the vertebrates. Development (Cambridge, England). 138(22):4969-4978.
Using zinc-finger nuclease-mediated mutagenesis, we have generated mutant alleles of the zebrafish orthologue of the chicken
talpid3 (ta3) gene, which encodes a centrosomal protein that is essential for ciliogenesis. Animals homozygous for these mutant alleles
complete embryogenesis normally, but manifest a cystic kidney phenotype during the early larval stages and die within a month
of hatching. Elimination of maternally derived Ta3 activity by germline replacement resulted in embryonic lethality of ta3 homozygotes. The phenotype of such maternal and zygotic (MZta3) mutant zebrafish showed strong similarities to that of chick ta3 mutants: absence of primary and motile cilia as well as aberrant Hedgehog (Hh) signalling, the latter manifest by the expanded
domains of engrailed and ptc1 expression in the somites, reduction of nkx2.2 expression in the neural tube, symmetric pectoral fins, cyclopic eyes and an ectopic lens. GFP-tagged Gli2a localised to
the basal bodies in the absence of the primary cilia and western blot analysis showed that Gli2a protein is aberrantly processed
in MZta3 embryos. Zygotic expression of ta3 largely rescued the effects of maternal depletion, but the motile cilia of Kupffer’s vesicle remained aberrant, resulting
in laterality defects. Our findings underline the importance of the primary cilium for Hh signaling in zebrafish and reveal
the conservation of Ta3 function during vertebrate evolution.