Transcriptional Dysregulation Underlies Both Monogenic Arrhythmia Syndrome and Common Modifiers of Cardiac Repolarization

• Published in: Circulation (New York, N.Y.) Vol. 147; no. 10; pp. 824 - 840
• Main Authors: Bersell, Kevin R., Yang, Tao, Mosley, Jonathan D., Glazer, Andrew M., Hale, Andrew T., Kryshtal, Dmytro O., Kim, Kyungsoo, Steimle, Jeffrey D., Brown, Jonathan D., Salem, Joe-Elie, Campbell, Courtney C., Hong, Charles C., Wells, Quinn S., Johnson, Amanda N., Short, Laura, Blair, Marcia A., Behr, Elijah R., Petropoulou, Evmorfia, Jamshidi, Yalda, Benson, Mark D., Keyes, Michelle J., Ngo, Debby, Vasan, Ramachandran S., Yang, Qiong, Gerszten, Robert E., Shaffer, Christian, Parikh, Shan, Sheng, Quanhu, Kannankeril, Prince J., Moskowitz, Ivan P., York, John D., Wang, Thomas J., Knollmann, Bjorn C., Roden, Dan M.
• Format: Journal Article
• Language: English
• Published: United States Lippincott Williams & Wilkins 07.03.2023; American Heart Association
• Subjects: Animals; Arrhythmias, Cardiac - genetics; Arrhythmias, Cardiac - metabolism; Brugada Syndrome; Humans; Life Sciences; Mice; Myocytes, Cardiac - metabolism; NAV1.5 Voltage-Gated Sodium Channel - genetics; NAV1.5 Voltage-Gated Sodium Channel - metabolism; Phenotype; Phosphatidylinositol 3-Kinases - metabolism; Receptors, Platelet-Derived Growth Factor - genetics; Receptors, Platelet-Derived Growth Factor - metabolism; Sodium - metabolism; stem cells; genetics; Brugada syndrome; arrhythmia
• ISSN: 0009-7322; 1524-4539; 1524-4539
• DOI: 10.1161/CIRCULATIONAHA.122.062193

Brugada syndrome (BrS) is an inherited arrhythmia syndrome caused by loss-of-function variants in the cardiac sodium channel gene (sodium voltage-gated channel alpha subunit 5) in ≈20% of subjects. We identified a family with 4 individuals diagnosed with BrS harboring the rare G145R missense variant in the cardiac transcription factor (T-box transcription factor 5) and no variant. We generated induced pluripotent stem cells (iPSCs) from 2 members of a family carrying TBX5-G145R and diagnosed with Brugada syndrome. After differentiation to iPSC-derived cardiomyocytes (iPSC-CMs), electrophysiologic characteristics were assessed by voltage- and current-clamp experiments (n=9 to 21 cells per group) and transcriptional differences by RNA sequencing (n=3 samples per group), and compared with iPSC-CMs in which G145R was corrected by CRISPR/Cas9 approaches. The role of platelet-derived growth factor (PDGF)/phosphoinositide 3-kinase (PI3K) pathway was elucidated by small molecule perturbation. The rate-corrected QT (QTc) interval association with serum PDGF was tested in the Framingham Heart Study cohort (n=1893 individuals). TBX5-G145R reduced transcriptional activity and caused multiple electrophysiologic abnormalities, including decreased peak and enhanced "late" cardiac sodium current (I ), which were entirely corrected by editing G145R to wild-type. Transcriptional profiling and functional assays in genome-unedited and -edited iPSC-CMs showed direct down-regulation caused decreased peak I , and that reduced PDGF receptor ( [platelet-derived growth factor receptor α]) expression and blunted signal transduction to PI3K was implicated in enhanced late I . Tbx5 regulation of the PDGF axis increased arrhythmia risk due to disruption of PDGF signaling and was conserved in murine model systems. PDGF receptor blockade markedly prolonged normal iPSC-CM action potentials and plasma levels of PDGF in the Framingham Heart Study were inversely correlated with the QTc interval ( <0.001). These results not only establish decreased transcription by the variant as a cause of BrS, but also reveal a new general transcriptional mechanism of arrhythmogenesis of enhanced late sodium current caused by reduced PDGF receptor-mediated PI3K signaling.