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Pathogenic variants of the Chloride intracellular ion channel 2 (CLIC2) are implicated in hypertrophic cardiomyopathy (HCM), a diverse heart condition leading to arrhythmic sudden cardiac death and heart failure. CLIC2 is a unique class of metamorphic protein, related to the enzymatic glutathione s-transferase family and form functional ion channel. Artificial bilayer studies have shown that CLIC2 negatively modulates the activity of cardiac ryanodine receptor 2 (RyR2), implicating the sarcoplasmic/endoplasmic reticulum (SR/ER) Ca 2+ release. However, the subsequent consequences of RyR2 and CLIC2 interaction in cardiac physiology remains unknown. Therefore, we ablated clic2 in human induced pluripotent stem cell (hiPSC) line using the CRISPR-Cas9 system and performed cardiomyocyte differentiation. clic2 −/− hiPSC-derived cardiomyocytes (hiPSC-CMs) showed altered electrophysiological properties leading to impaired excitation-contraction coupling. clic2 −/− hiPSC-CMs showed an increase in beat rate and field potential duration by 143.49±5.96% and 162.43±5.82%, respectively, whereas conduction velocity and spike amplitude decreased by 43.81±2.22% and 43.32±3.54%, respectively compared to WT hiPSC-CMs. Additionally, action potential duration measurements of clic2 −/− hiPSC-CMs showed a decrease in APD30, APD50, and APD90 by 74.42%, 65.19%, and 66.46%, respectively compared to WT hiPSC-CMs. Moreover, clic2 −/− hiPSC-CMs showed altered Ca 2+ handling, with a decrease in peak amplitude (57.07±2.25%) and duration (38.29±1.30%) compared to the WT hiPSC-CMs. The caffeine induced Ca 2+ release in clic2 −/− hiPSC-CMs, attributed to the SR/ER Ca 2+ overload which decreased by 72.19±3.51% compared to WT hiPSC-CMs. Transcriptomics analysis of clic2 −/− hiPSC-CMs revealed 223 transcripts with significant changes in expression levels (89 upregulated and 134 downregulated), implicating CLIC2 in hypertrophy cardiomyopathy, dilated cardiomyopathy, and other heart diseases. Furthermore, the protein expression of CLIC2 increases in end-stage failing human heart samples compared to the non-failing heart. In conclusion, our study sheds light on the novel role of CLIC2 in the regulation of cardiac (patho)physiology. National Institutes of Health (NIH) (HL133050, and HL157453); American Heart Association-Transformational Project Award; National Center for advancing translational sciences (TR004178, understudied proteins and druggable targets) (HS). Presidential Predoctoral Fellowship; Margaret T. Nishikawara Merit Scholarship Endowment in Physiology; Graduate School’s Alumni Grants for Graduate Research and Scholarship Program, The Ohio State University (SS). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Sanghvi et al. (Wed,) studied this question.