Mutations in KCNK4 that Affect Gating Cause a Recognizable Neurodevelopmental Syndrome

Area of Science:

• Genetics
• Molecular Biology
• Neuroscience

Background:

• Potassium (K+) currents regulate cellular excitability and are implicated in various physiological processes.
• The KCNK4 (TRAAK) channel, a member of the two-pore-domain (K2P) K+ channel family, is involved in mechano-gated ion transport.
• The role of K2P channels in human diseases is not well understood.

Purpose of the Study:

• To identify the genetic cause of a novel neurodevelopmental syndrome.
• To characterize the functional consequences of identified mutations in the KCNK4 gene.
• To elucidate the molecular mechanism underlying KCNK4 channel dysfunction in disease.

Main Methods:

• Whole-exome sequencing to identify de novo mutations.
• Patch-clamp electrophysiology to assess KCNK4 channel function.
• Co-expression studies and molecular dynamics simulations to investigate mutation effects.

Main Results:

• Identified de novo missense mutations in KCNK4 associated with a syndrome named FHEIG (facial dysmorphism, hypertrichosis, epilepsy, intellectual disability/developmental delay, and gingival overgrowth).
• Demonstrated a gain-of-function effect for KCNK4 mutants, with reduced sensitivity to mechanical stimuli and arachidonic acid.
• Mutations were found to favor the sealing of lateral intramembrane fenestrations, potentially altering channel gating.

Conclusions:

• Dysregulation of KCNK4 channel function due to de novo mutations causes a distinct neurodevelopmental syndrome (FHEIG).
• Findings support a model where lateral fenestrations in K2P channels play a crucial role in regulating ion flow.
• This study highlights the pleiotropic effects of KCNK4 dysfunction and advances understanding of K2P channel gating mechanisms.