Characterization of zebrafish gp1ba mutant and modelling Bernard Soulier syndrome.

The aim of this study is to model classical Bernard Soulier Syndrome in the zebrafish by targeting Gp1ba. We obtained gp1ba mutant embryos from Zebrafish International Resource Center and grew them to adulthood. The tail clips from these fish were used to prepare DNA and sequenced to identify heterozygotes. They were then bred to obtain homozygotes. The mutation was confirmed by DNA sequencing as a termination codon UAA in place of AAA codon at position 886 in the gp1ba transcript. Thus, at the Pro-295, the Gp1ba protein could be terminated. The blood from gp1ba homozygous and heterozygous mutants showed decreased ristocetin-mediated agglutination in the whole blood agglutination assay. The gp1ba heterozygous and homozygous larvae were subjected to a laser-assisted arterial thrombosis assay, and the results showed the prolonged occlusion in the caudal artery. These results suggested that the gp1ba mutant had a bleeding phenotype. The blood smears from the adult gp1ba, heterozygous and homozygous mutants, showed macrothrombocytes, similar to the human GP1BA deficiency that showed giant platelets. The bleeding assay on these heterozygous and homozygous mutants showed greater bleeding than wildtype, confirming the above findings. Taken together, the characterization of gp1ba zebrafish mutant suggested an autosomal dominant mode of inheritance. The zebrafish gp1ba mutant models classical Bernard Soulier Syndrome and could be used for reversing this phenotype to identify novel factors by the genome-wide piggyback knockdown method.