The W101C KCNJ5 Mutation Induces Slower Pacing by Constitutively Active GIRK Channels in hiPSC-Derived Cardiomyocytes

TY - JOUR

T1 - The W101C KCNJ5 Mutation Induces Slower Pacing by Constitutively Active GIRK Channels in hiPSC-Derived Cardiomyocytes

AU - Kayser, Anne

AU - Dittmann, Sven

AU - Šarić, Tomo

AU - Mearini, Giulia

AU - Verkerk, Arie O

AU - Schulze-Bahr, Eric

PY - 2023/10/18

Y1 - 2023/10/18

N2 - Mutations in the KCNJ5 gene, encoding one of the major subunits of cardiac G-protein-gated inwardly rectifying K+ (GIRK) channels, have been recently linked to inherited forms of sinus node dysfunction. Here, the pathogenic mechanism of the W101C KCNJ5 mutation underlying sinus bradycardia in a patient-derived cellular disease model of sinus node dysfunction (SND) was investigated. A human-induced pluripotent stem cell (hiPSCs) line of a mutation carrier was generated, and CRISPR/Cas9-based gene targeting was used to correct the familial mutation as a control line. Both cell lines were further differentiated into cardiomyocytes (hiPSC-CMs) that robustly expressed GIRK channels which underly the acetylcholine-regulated K+ current (IK,ACh). hiPSC-CMs with the W101C KCNJ5 mutation (hiPSCW101C-CM) had a constitutively active IK,ACh under baseline conditions; the application of carbachol was able to increase IK,ACh, further indicating that not all available cardiac GIRK channels were open at baseline. Additionally, hiPSCW101C-CM had a more negative maximal diastolic potential (MDP) and a slower pacing frequency confirming the bradycardic phenotype. Of note, the blockade of the constitutively active GIRK channel with XAF-1407 rescued the phenotype. These results provide further mechanistic insights and may pave the way for the treatment of SND patients with GIRK channel dysfunction.

AB - Mutations in the KCNJ5 gene, encoding one of the major subunits of cardiac G-protein-gated inwardly rectifying K+ (GIRK) channels, have been recently linked to inherited forms of sinus node dysfunction. Here, the pathogenic mechanism of the W101C KCNJ5 mutation underlying sinus bradycardia in a patient-derived cellular disease model of sinus node dysfunction (SND) was investigated. A human-induced pluripotent stem cell (hiPSCs) line of a mutation carrier was generated, and CRISPR/Cas9-based gene targeting was used to correct the familial mutation as a control line. Both cell lines were further differentiated into cardiomyocytes (hiPSC-CMs) that robustly expressed GIRK channels which underly the acetylcholine-regulated K+ current (IK,ACh). hiPSC-CMs with the W101C KCNJ5 mutation (hiPSCW101C-CM) had a constitutively active IK,ACh under baseline conditions; the application of carbachol was able to increase IK,ACh, further indicating that not all available cardiac GIRK channels were open at baseline. Additionally, hiPSCW101C-CM had a more negative maximal diastolic potential (MDP) and a slower pacing frequency confirming the bradycardic phenotype. Of note, the blockade of the constitutively active GIRK channel with XAF-1407 rescued the phenotype. These results provide further mechanistic insights and may pave the way for the treatment of SND patients with GIRK channel dysfunction.

KW - Humans

KW - Myocytes, Cardiac/metabolism

KW - Induced Pluripotent Stem Cells/metabolism

KW - Sick Sinus Syndrome/genetics

KW - Mutation

KW - Arrhythmias, Cardiac/metabolism

KW - Acetylcholine/metabolism

KW - G Protein-Coupled Inwardly-Rectifying Potassium Channels/genetics

U2 - 10.3390/ijms242015290

DO - 10.3390/ijms242015290

M3 - SCORING: Journal article

C2 - 37894977

VL - 24

SP - 15290

JO - INT J MOL SCI

JF - INT J MOL SCI

SN - 1661-6596

IS - 20

ER -