Shan Gao, Dan Ye, Raquel Neves, Cs John Kim, David J Tester, Wei Zhou, John R Giudicessi, Michael J Ackerman
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引用次数: 0
Abstract
Background: Genome sequencing of a pedigree with familial ventricular fibrillation identified an ultrarare missense variant, p.R534S, in the DENND3 gene. DENND3 is a guanine nucleotide exchange factor for Rab guanosine triphosphatases (GTPases), which regulate intracellular membrane trafficking, including cardiac ion channels.
Objective: The purpose of this study was to assess the impact of DENND3 as a potential genetic modifier contributing to lethal arrhythmia syndromes including familial ventricular fibrillation.
Methods: The variant's impact was assessed using induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and TSA201 cells. Super-resolution Airyscan imaging (LSM980 Zeiss, Jena, Germany) and the GTPase-Glo assay (Promega, Madison, WI) were used to investigate the distribution and activity of Rab proteins. Electrophysiological analyses measured ion channel currents and cellular arrhythmogenicity.
Results: The DENND3-p.R534S variant increased the membrane localization of KCNQ1-, KCNH2-, SCN5A-, and CACNA1C-encoded ion channels in both TSA201 cells and iPSC-CMs. Electrophysiological studies revealed an increase in KCNH2-encoded rapid delayed rectifying K+ channel and CACNA1C-encoded L-type calcium channel. iPSC-CMs expressing DENND3-p.R534S exhibited erratic electrical activity, including irregular beating patterns, early afterdepolarizations, and delayed afterdepolarizations. Rab5 showed ectopic distribution in cells expressing DENND3-p.R534S, while other Rab proteins did not display such changes. The GTPase activity of Rab5 increased, while Rab12 activity decreased in the presence of the variant.
Conclusion: Our findings unveiled a mechanism whereby the DENND3-p.R534S variant disrupts Rab-mediated trafficking pathways critical for ion channel distribution and cellular function. This study reveals for the first time a potential association of DENND3 and Rab GTPases in cardiac physiology and arrhythmogenic risk.
期刊介绍：
HeartRhythm, the official Journal of the Heart Rhythm Society and the Cardiac Electrophysiology Society, is a unique journal for fundamental discovery and clinical applicability.
HeartRhythm integrates the entire cardiac electrophysiology (EP) community from basic and clinical academic researchers, private practitioners, engineers, allied professionals, industry, and trainees, all of whom are vital and interdependent members of our EP community.
The Heart Rhythm Society is the international leader in science, education, and advocacy for cardiac arrhythmia professionals and patients, and the primary information resource on heart rhythm disorders. Its mission is to improve the care of patients by promoting research, education, and optimal health care policies and standards.
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