An epilepsy-associated KCNT1 mutation enhances excitability of human iPSC-derived neurons by increasing slack KNa currents

Imran H. Quraishi, Shani Stern, Kile P. Mangan, Yalan Zhang, Syed R. Ali, Michael R. Mercier, Maria C. Marchetto, Michael J. McLachlan, Eugenia M. Jones, Fred H. Gage, Leonard K. Kaczmarek

Research output: Contribution to journalArticlepeer-review


Mutations in the KCNT1 (Slack, KNa1.1) sodium-activated potassium channel produce severe epileptic encephalopathies. Expression in heterologous systems has shown that the disease-causing mutations give rise to channels that have increased current amplitude. It is not known, however, whether such gain of function occurs in human neurons, nor whether such increased KNa current is expected to suppress or increase the excitability of cortical neurons. Using genetically engineered human induced pluripotent stem cell (iPSC)-derived neurons, we have now found that sodium-dependent potassium currents are increased several-fold in neurons bearing a homozygous P924L mutation. In current-clamp recordings, the increased KNa current in neurons with the P924L mutation acts to shorten the duration of action potentials and to increase the amplitude of the afterhyperpolarization that follows each action potential. Strikingly, the number of action potentials that were evoked by depolarizing currents as well as maximal firing rates were increased in neurons expressing the mutant channel. In networks of spontaneously active neurons, the mean firing rate, the occurrence of rapid bursts of action potentials, and the intensity of firing during the burst were all increased in neurons with the P924L Slack mutation. The feasibility of an increased KNa current to increase firing rates independent of any compensatory changes was validated by numerical simulations. Our findings indicate that gain-of-function in Slack KNa channels causes hyperexcitability in both isolated neurons and in neural networks and occurs by a cell-autonomous mechanism that does not require network interactions.

Original languageEnglish
Pages (from-to)7438-7449
Number of pages12
JournalJournal of Neuroscience
Issue number37
StatePublished - 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
Copyright © 2019 the authors


  • Action potential
  • Epileptic encephalopathy
  • Potassium channels
  • Seizures

ASJC Scopus subject areas

  • General Neuroscience


Dive into the research topics of 'An epilepsy-associated KCNT1 mutation enhances excitability of human iPSC-derived neurons by increasing slack KNa currents'. Together they form a unique fingerprint.

Cite this