Neonatal diabetes is a rare form of diabetes that is usually detected within the first six months of life. Approximately 50% of cases of neonatal diabetes are caused by mutations in either the KIR6.2 gene or the SUR1 gene. Frances Ashcroft and colleagues, at Oxford University, United Kingdom, have now developed a mouse model of neonatal diabetes that they believe provides new insight into the human disease.
In the study, mice were engineered to express in the beta-cells of their pancreas a mutant Kir6.2 protein (V59M) that causes neonatal diabetes in humans. These beta-V59M mice developed diabetes soon after birth, and by 5 weeks of age blood glucose levels were markedly increased and the hormone insulin was undetectable, two hallmarks of diabetes. This was because beta-cells of the pancreas were secreting less insulin as a result of the mutant Kir6.2 protein, which forms a complex known as a KATP channel with the protein made from the SUR1 gene. When pancreata from 5 week old beta-V59M mice were treated with a drug that inhibits KATP channel activity, beta-cells of the pancreata started secreting insulin again. Thus, expression of the V59M mutant Kir6.2 in mouse pancreatic beta cells alone is sufficient to recapitulate human neonatal diabetes.
TITLE: Expression of an activating mutation in the gene encoding the KATP channel subunit Kir6.2 in mouse pancreatic beta cells recapitulates neonatal diabetes
Frances M. Ashcroft
University of Oxford, Oxford, United Kingdom.
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