Phenotypic Expression Caused by glis3 Knockout in Zebrafish, Danio rerio

The transcription factor Gli-similar 3 (Glis3) has been shown to play a critical role in the development of insulin producing β-cells in the pancreas and is required for the proper expression of insulin in mature cells. Mutations within the human GLIS3 locus are responsible for a number of pathologies including diabetes mellitus and polycystic kidney disease. By understanding the role that Glis3 plays in β-cell development, it may be possible to develop a model for studying insulin related diseases. In this study, zebrafish (Danio rerio) were generated that lack functional glis3 expression due to an ENU mutagenesis-induced nonsense mutation within exon2 of glis3 that results in a protein truncated at Thr47. The resulting protein product lacks its centrally located DNA binding domain and the C-terminal transactivation domain. Homozygous and heterozygous glis3 mutants where genotyped using TaqMan SNP genotyping assays and analyzed for phenotypic abnormalities. Adult homozygous knockout animals where analyzed to determine if the loss of glis3 resulted in perturbation of normal weight and body mass indices (mass/length2). Examination of mutants by histological analysis indicated that homozygous loss of glis3 resulted in the development of cysts within the pronephric tubules by 48 hpf. Future studies will investigate the role of glis3 in specification of pancreas development and susceptibility of glis3 mutants to type 2 diabetes following nutrient excess. Understanding the role of glis3 during development and its function in mature organisms may provide insight into the etiology of GLIS3-related disease in humans and may help identify potential therapeutic targets