# KCNJ2-Induced Arrhythmia Mechanisms in CPVT and Heart Failure.

> **NIH NIH R01** · UNIVERSITY OF WISCONSIN-MADISON · 2020 · $381,228

## Abstract

Arrhythmic sudden cardiac death (SCD) is a leading cause of death in the United States and can be caused by
ionic current abnormalities occurring in genetic arrhythmia syndromes or acquired heart disease such as heart
failure. This project focuses on the impact of cardiac inward rectifier current (IK1) on -adrenergic-dependent
genetic and acquired ventricular arrhythmias. IK1 maintains resting membrane potential, contributes to phase 3
repolarization, and is remodeled in heart failure. KCNJ2 encodes the ion channel Kir2.1 that forms the
dominant protein pore subunit for IK1 in the human cardiac ventricle. Loss of function KCNJ2 mutations present
with two clinical phenotypes, Adersen-Tawil Syndrome (ATS), composed of a triad of ventricular arrhythmias,
dysmorphic features and periodic paralysis, or Catecholaminergic Polymorphic Ventricular Tachycardia
(CPVT), which presents with adrenergic-dependent ventricular arrhythmias including polymorphic ventricular
tachycardia (PMVT) and bidirectional VT (BiVT) with a lack non-cardiac ATS features. CPVT has been
attributed to abnormal calcium (Ca2+) handling related to mutations in Ca2+ handling genes and the signature
arrhythmia for CPVT, BiVT, is caused by Ca2+ overload. Unlike the other CPVT targets, Kir2.1 does not directly
participate in Ca2+ homeostasis, yet Ca2+ modulates Kir2.1 by specifically blocking the outward Kir2.1 current.
-adrenergic stimulation activates protein-kinase A (PKA), which phosphorylates Kir2.1 with subsequent
increase in outward Kir2.1 current. How Kir2.1 with CPVT-causing mutations fail to respond to PKA is
unknown, particularly since the known CPVT mutations are not phosphorylation sites. Our central hypothesis is
that under -adrenergic stimulation, CPVT-causing Kir2.1 mutant channels have loss of outward current due to
both lack of a PKA response and increased sensitivity to Ca2+ block, reducing outward current and thus
repolarization drive causing membrane potential instability, favoring delayed after-depolarizations (DADs)
triggered activity. Additionally, decreased IK1 in systolic heart failure is thought to be a key feature in ventricular
arrhythmias and SCD. We hypothesize that IK1 is decreased predominately during -adrenergic stimulation due
to elevated Ca2+ in a manner similar to CPVT-causing KCNJ2 mutations. In this study, we will address these
questions using a variety of cellular models and transgenic mouse models to determine the biophysical
properties, Ca2+ sensitivity, phosphorylation state and arrhythmia mechanism of KCNJ2 mutations associated
with a CPVT or an ATS phenotype and compare that to a heart failure model. Our innovative methods will
include high-definition mass spectrometry, optical mapping and calcium imaging. The outcomes of this
research will allow us to elucidate the mechanism by which -adrenergic-dependent loss of IK1 can result in
ventricular arrhythmia in CPVT and heart failure and compare that to an ATS arrhythmia mechanism.
Elucidating...

## Key facts

- **NIH application ID:** 9975894
- **Project number:** 5R01HL139738-03
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** Lee Lochbaum Eckhardt
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $381,228
- **Award type:** 5
- **Project period:** 2018-08-01 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9975894

## Citation

> US National Institutes of Health, RePORTER application 9975894, KCNJ2-Induced Arrhythmia Mechanisms in CPVT and Heart Failure. (5R01HL139738-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9975894. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*