Abstract Or101: Phospho-Mimic Mutation in Beta Tubulin Suppresses Arrhythmias and Improves Cardiac Connexin 43 Localization in Duchenne Muscular Dystrophy Mice

• Published in: Circulation research Vol. 135; no. Suppl_1
• Main Authors: Zhou, Delong, Nouet, Julie, Mesa, Elam, Geukgeuzian, Geovanni, Li, Hong, Liu, Tong, Yehia, Ghassan, Romanienko, Peter, Rodney, George, Wehrens, Xander, Lampe, Paul, Gourdie, Robert, Xie, Lai-Hua, Fraidenraich, Diego
• Format: Journal Article
• Language: English
• Published: 02.08.2024
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/res.135.suppl_1.Or101

Abstract only Duchenne Muscular Dystrophy (DMD) is a severe X-linked neuromuscular disorder, causing progressive muscle degeneration and premature death due to heart and skeletal muscle dysfunction. It is caused by mutations in the dmd gene, leading to the absence of dystrophin, a crucial protein for muscle integrity. There is no cure for DMD. Its associated dystrophic cardiomyopathy is the primary cause of mortality by age 20. Connexin-43 (Cx43) is a gap junction protein responsible for electrical signaling in the heart. Cx43 localizes at the intercalated disc of the cardiomyocyte (CM), forming an intercellular channel with adjacent CMs; In DMD, Cx43 hemichannel remodels to the lateral side of the cardiomyocyte. Our previous research indicated that phospho-mimic Cx43 carrying serine to glutamic acid substitutions at the triplet regulatory site S325, S328, S330 in mdx hearts suppressed Cx43 lateralization and improved cardiac rhythm. The phospho-mimic Cx43 also reduced pathological hyperdensity and transverse directionality of microtubules in mdx cardiomyocytes. Colchicine (Colch) treatment, known to inhibit microtubule polymerization, also improved cardiac rhythm and Cx43 localization in mdx mice. To phenocopy the effect observed with Colch, we generated a mouse model with a beta tubulin mutation at serine 172, which was replaced by glutamic acid (S172E). We found reduced arrhythmias and improved localization of Cx43 in mdx hearts carrying the S172E phospho-mimic mutant tubulin by electrocardiography and immunofluorescent staining, respectively. Moreover, the proteomics data showed that the level of phospho-Cx43 was also upregulated in mdx hearts with S172E tubulin mutation. Further investigation will explore how this mutation impacts protein regulation and electrophysiology, and elucidate its mechanism of action in microtubule polymerization. These studies investigate a regulatory link between microtubule dynamics and localization of Cx43, potentially suggesting a novel therapeutic target for DMD-associated cardiomyopathy.