Altered Kcnh2/Kv11.1 Expression in the Brain and Heart, and Prolongation of Cardiac Repolarization in a Rabbit Model of Long QT Syndrome with Seizures
Abstract number :
3.054
Submission category :
1. Basic Mechanisms / 1E. Models
Year :
2023
Submission ID :
1026
Source :
www.aesnet.org
Presentation date :
12/4/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: Kyle Wagner, BS – SUNY UpState Medical University
David Auerbach, PhD – SUNY Upstate Medical University; Roshanak Ebrahimi, MS – SUNY Upstate Medical University; Katherine Keller, MS – SUNY Upstate Medical University; Justin Ryan, PhD – SUNY Upstate Medical University; Richard Wojcikiewicz, PhD – SUNY Upstate Medical University
Rationale: Long QT Syndrome (LQTS) is due to variants in genes that encode proteins that form or associate with ion channels. These variants can result in QT prolongation, and a high risk of cardiac arrhythmias, epileptic seizures, and sudden death. LQT2 is due to loss-of-function variants in KCNH2, which encodes the Kv11.1 protein that forms the K+ channel responsible for the rapid component of the delayed rectifier K+ channel current, IKr. Using CRISPR-Cas9, we generated rabbits with a heterozygous frameshift mutation in the Kcnh2 pore-domain (Kcnh2(+/mut)). These include a 7 base pair deletion (7BP), a 43 base pair deletion (43BP), and an A561V missense mutation with a 127 base pair repeat sequence insertion (A561V+). The rabbits reproduce the human LQT2 phenotype of epileptic seizures, cardiac arrhythmias (demonstrated below), and sudden death. We tested for genotype-specific differences in Kcnh2 and Kv11.1 expression patterns in the brain and heart, as well as tested for differences in cardiac ECG measures in WT and each of the 3 Kcnh2(+/mut) rabbit lines.
Methods: We performed PCR to determine if mutant Kcnh2 is expressed in the brain and heart. Additionally, using qPCR we quantified the amount of total and WT Kcnh2 in each of the rabbit lines. Western Blot analysis was used to test for differences in full-length WT Kv11.1 protein in the heart and brain of our rabbits. We evaluated cardiac ventricular repolarization measures in conscious restrained WT and mutant rabbits during 5-minute non-seizure baseline periods.
Results: Using mutant specific primers, we identifed the 7BP and 43BP mutant Kcnh2 transcripts, but not the A561V+ Kcnh2 transcrip. Total and WT Kcnh2 transcript is significantly higher in Kcnh2(+7BP) and Kcnh2(+/43BP) vs. WT rabbit tissue. In contrast, Western blot analysis indicates that full-length WT Kv11.1 levels are lower in each of the mutant lines compared to WT rabbit heart and brain tissue. In vivo ECG analysis demonstrates that there is a significant prolongation of ventricular repolarization (QT, QTc, and QT-peak) in Kcnh2(+/mut) vs. WT rabbits.
Conclusions: Kcnh2(+/mut) rabbits exhibit alterations in Kcnh2 and Kv11.1 expression in the brain and heart, as well as prolongation of cardiac repolarization.
Funding: American Heart Association
SUNY Upstate Startup Funds
Basic Mechanisms