A missense KCNQ1 Mutation Impairs Insulin Secretion in Neonatal Diabetes

Abstract

KCNQ1/Kv7 is a voltage-gated K+ channel that regulates heart rhythm, glucose and salt homeostasis. Mutations of KCNQ1 are primarily associated with long-QT syndrome and type 2 diabetes; however, thus far KCNQ1 mutations have not been associated with monogenetic diabetes. Here, we identified a homozygous KCNQ1 missense mutation (R397W) in an individual with permanent neonatal diabetes (PND). To identify the mechanisms that link the mutation to the disease, we introduced the mutation into human embryonic stem cells (hESCs), and used them to derived pancreatic β-like cells (hESC-β cell). In early β-like cells, we observed atypical membrane electrical activity, increased levels of cytoplasmic Ca2+, and a hypersecretion of insulin. Upon extended culture, their insulin secretion decreased and the number of apoptotic cells increased, resulting in a reduction in the numbers of β-like cells. Late-stage β-like cells exhibited a decrease in the expression of metabolic genes, e.g. HNF4α, PDX1 and GLUT1, providing a possible mechanism for β-cell dysfunction. Our study identifies KCNQ1 as a novel candidate gene of monogenetic diabetes and shows that KCNQ1 regulates β-cell function and survival.