Genome-edited zebrafish model of ABCC8 loss-of-function disease

ATP-sensitive potassium channel (K_ATP)gain- (GOF) and loss-of-function (LOF) mutations underlie human neonatal diabetes mellitus (NDM) and hyperinsulinism (HI), respectively. While transgenic mice expressing incomplete K_ATP LOF do reiterate mild hyperinsulinism, K_ATP knockout animals do not exhibit persistent hyperinsulinism. We have shown that islet excitability and glucose homeostasis are regulated by identical K_ATP channels in zebrafish. SUR1 truncation mutation (K499X) was introduced into the abcc8 gene to explore the possibility of using zebrafish for modeling human HI. Patch-clamp analysis confirmed the complete absence of channel activity in β-cells from K499X (SUR1^-/-) fish. No difference in random blood glucose was detected in heterozygous SUR1+/- fish nor in homozygous SUR1^-/- fish, mimicking findings in SUR1 knockout mice. Mutant fish did, however, demonstrate impaired glucose tolerance, similar to partial LOF mouse models. In paralleling features of mammalian diabetes and hyperinsulinism resulting from equivalent LOF mutations, these gene-edited animals provide valid zebrafish models of K_ATP -dependent pancreatic diseases.