Neonatal diabetes is characterized by insulin-sensitive hyperglycemia usually diagnosed within the first six months of life. The prevalence of this condition is around 1 in 400,000 births. About 50% of all cases of neonatal diabetes are an effect of mutations in either the sulfonylurea receptor -1 gene (SUR1) or the KIR6.2 gene (polymorphisms of KCNJ11).
Researchers at Oxford University in the United Kingdom headed by Frances Ashcroft have now designed a mouse model of the disease that they strongly believe could provide significant information about this human disease.
In the breakthrough study, Ashcroft and colleagues genetically modified mice to express V59M, a mutant KIR6.2 protein, in the beta-cells of their pancreas. This mutant protein is primarily responsible for neonatal diabetes in humans.
The research team found that these beta-V59M mice contacted diabetes soon after their birth. By the time they reach the age of five weeks, the blood glucose levels of the mice significantly increased, while the hormone insulin could not be detected. These are the two major characteristics of diabetes.
The researchers explained that the mice developed diabetes because their pancreatic beta cells were producing less insulin due to the altered KIR6.2 protein. The mutant protein forms a complex called a KATP channel with the protein modified from the SUR1 gene.
When the researchers treated the pancreata from five-week-old beta-V59M mice with a drug that slows down KATP channel activity, they found that beta-cells of the pancreata began producing insulin again. Therefore, expression of the V59M mutant Kir6.2 in pancreatic beta cells of the mice alone provides sufficient evidence in the understanding of neonatal diabetes in humans.