Zhou Zhimin and Zsuzsanna Izsvak*
The KCNQ1/Kv7 channel, part of the Q1 subfamily of voltage-gated potassium channels, plays a key role in cardiac rhythm regulation and is commonly associated with Long QT syndrome (LQT1). Emerging evidence also suggests a role for KCNQ1 in insulin secretion, though its link to both hypersecretory and hyposecretory phenotypes complicates its connection between cardiac and metabolic syndromes. This complexity is further compounded by its epigenetic regulation and association with type 2 diabetes risk. The focal study investigated a unique case of Permanent Neonatal Diabetes Mellitus (PNDM) where KCNQ1/Kv7 dysfunction, typically linked to cardiac function, was identified as a novel contributor to the disease. Genetic analysis revealed a homozygous missense mutation in the KCNQ1 gene (C1189T/R397W) in a PNDM patient who did not exhibit overt cardiac symptoms. Using an in vitro Stem Cell (SC)-derived islet model and CRISPR/Cas9 gene editing, the study examined the mutation’s impact on pancreatic β-cell function. The results show that while the C1189T variant does not disrupt epigenetic regulation during pancreatic development or differentiation, it leads to a loss of KCNQ1 channel function, causing atypical electrophysiology. The SC model demonstrated that this impaired channel function results in a stage-dependent pattern of insulin secretion, characterized by initial hypersecretion followed by eventual pancreatic β-cell failure.
