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Troponin destabilization impairs sarcomere-cytoskeleton interactions in iPSC-derived cardiomyocytes from dilated cardiomyopathy patients.

ABSTRACT: The sarcomeric troponin-tropomyosin complex is a critical mediator of excitation-contraction coupling, sarcomeric stability and force generation. We previously reported that induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from patients with a dilated cardiomyopathy (DCM) mutation, troponin T (TnT)-R173W, display sarcomere protein misalignment and impaired contractility. Yet it is not known how TnT mutation causes dysfunction of sarcomere microdomains and how these events contribute to misalignment of sarcomeric proteins in presence of DCM TnT-R173W. Using a human iPSC-CM model combined with CRISPR/Cas9-engineered isogenic controls, we uncovered that TnT-R173W destabilizes molecular interactions of troponin with tropomyosin, and limits binding of PKA to local sarcomere microdomains. This attenuates troponin phosphorylation and dysregulates local sarcomeric microdomains in DCM iPSC-CMs. Disrupted microdomain signaling impairs MYH7-mediated, AMPK-dependent sarcomere-cytoskeleton filament interactions and plasma membrane attachment. Small molecule-based activation of AMPK can restore TnT microdomain interactions, and partially recovers sarcomere protein misalignment as well as impaired contractility in DCM TnT-R173W iPSC-CMs. Our findings suggest a novel therapeutic direction targeting sarcomere- cytoskeleton interactions to induce sarcomere re-organization and contractile recovery in DCM.

SUBMITTER: Dai Y

PROVIDER: S-EPMC6959358 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Troponin destabilization impairs sarcomere-cytoskeleton interactions in iPSC-derived cardiomyocytes from dilated cardiomyopathy patients.

Dai Yuanyuan Y Amenov Asset A Ignatyeva Nadezda N Koschinski Andreas A Xu Hang H Soong Poh Loong PL Tiburcy Malte M Linke Wolfgang A WA Zaccolo Manuela M Hasenfuss Gerd G Zimmermann Wolfram-Hubertus WH Ebert Antje A

Scientific reports 20200114 1

The sarcomeric troponin-tropomyosin complex is a critical mediator of excitation-contraction coupling, sarcomeric stability and force generation. We previously reported that induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from patients with a dilated cardiomyopathy (DCM) mutation, troponin T (TnT)-R173W, display sarcomere protein misalignment and impaired contractility. Yet it is not known how TnT mutation causes dysfunction of sarcomere microdomains and how these events contribu ...[more]

PMID: 31937807

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Project description:RationaleThe E2F pathway plays a critical role in cardiac growth and development, yet its role in cardiac metabolism remains to be defined. Metabolic changes play important roles in human heart failure and studies imply the ketogenic enzyme ?-hydroxybutyrate dehydrogenase I (BDH1) is a potential biomarker.ObjectiveTo define the role of the E2F pathway in cardiac metabolism and dilated cardiomyopathy (DCM) with a focus on BDH1.Methods and resultsWe previously developed transgenic (Tg) mice expressing the transcriptional repressor, E2F6, to interfere with the E2F/Rb pathway in post-natal myocardium. These Tg mice present with an E2F6 dose dependent DCM and deregulated connexin-43 (CX-43) levels in myocardium. Using the Seahorse platform, a 22% decrease in glycolysis was noted in neonatal cardiomyocytes isolated from E2F6-Tg hearts. This was associated with a 39% reduction in the glucose transporter GLUT4 and 50% less activation of the regulator of glucose metabolism AKT2. The specific reduction of cyclin B1 (70%) in Tg myocardium implicates its importance in supporting glycolysis in the postnatal heart. No changes in cyclin D expression (known to regulate mitochondrial activity) were noted and lipid metabolism remained unchanged in neonatal cardiomyocytes from Tg hearts. However, E2F6 induced a 40-fold increase of the Bdh1 transcript and 890% increase in its protein levels in hearts from Tg pups implying a potential impact on ketolysis. By contrast, BDH1 expression is not activated until adulthood in normal myocardium. Neonatal cardiomyocytes from Wt hearts incubated with the ketone ?-hydroxybutyrate (?-OHB) showed a 100% increase in CX-43 protein levels, implying a role for ketone signaling in gap junction biology. Neonatal cardiomyocyte cultures from Tg hearts exhibited enhanced levels of BDH1 and CX-43 and were not responsive to ?-OHB.ConclusionsThe data reveal a novel role for the E2F pathway in regulating glycolysis in the developing myocardium through a mechanism involving cyclin B1. We reveal BDH1 expression as an early biomarker of heart failure and its potential impact, through ketone signaling, on CX-43 levels in E2F6-induced DCM.

Dataset Information

Troponin destabilization impairs sarcomere-cytoskeleton interactions in iPSC-derived cardiomyocytes from dilated cardiomyopathy patients.

Publications

Troponin destabilization impairs sarcomere-cytoskeleton interactions in iPSC-derived cardiomyocytes from dilated cardiomyopathy patients.

Similar Datasets

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