Disruption of Ca 2+ i Homeostasis and Connexin 43 Hemichannel Function in the Right Ventricle Precedes Overt Arrhythmogenic Cardiomyopathy in Plakophilin-2–Deficient Mice

Autor: Marta Pérez-Hernández, Jérôme Montnach, Sun-Hee Woo, Svetlana Rajkumar Maurya, Mingliang Zhang, Alicia Lundby, Xianming Lin, Carolina Vasquez, Yandong Yin, Francisco J. Alvarado, Eli Rothenberg, Feng-Xia Liang, Adriana Heguy, Marina Cerrone, Joon-Chul Kim, Gregory E. Morley, Héctor H. Valdivia, Mario Delmar
Rok vydání: 2019
Předmět:
Zdroj: Kim, J-C, Perez-Hernandez, M, Alvarado, F J, Maurya, S R, Montnach, J, Yin, Y, Zhang, M, Lin, X, Vasquez, C, Heguy, A, Liang, F-X, Woo, S-H, Morley, G E, Rothenberg, E, Lundby, A, Valdivia, H H, Cerrone, M & Delmar, M 2019, ' Disruption of Ca 2+ i Homeostasis and Connexin 43 Hemichannel Function in the Right Ventricle Precedes Overt Arrhythmogenic Cardiomyopathy in Plakophilin-2-Deficient Mice ', Circulation, vol. 140, no. 12, pp. 1015-1030 . https://doi.org/10.1161/CIRCULATIONAHA.119.039710
ISSN: 1524-4539
0009-7322
DOI: 10.1161/circulationaha.119.039710
Popis: Background: Plakophilin-2 (PKP2) is classically defined as a desmosomal protein. Mutations in PKP2 associate with most cases of gene-positive arrhythmogenic right ventricular cardiomyopathy. A better understanding of PKP2 cardiac biology can help elucidate the mechanisms underlying arrhythmic and cardiomyopathic events consequent to PKP2 deficiency. Here, we sought to capture early molecular/cellular events that can act as nascent arrhythmic/cardiomyopathic substrates. Methods: We used multiple imaging, biochemical and high-resolution mass spectrometry methods to study functional/structural properties of cells/tissues derived from cardiomyocyte-specific, tamoxifen-activated, PKP2 knockout mice (PKP2cKO) 14 days post-tamoxifen injection, a time point preceding overt electrical or structural phenotypes. Myocytes from right or left ventricular free wall were studied separately. Results: Most properties of PKP2cKO left ventricular myocytes were not different from control; in contrast, PKP2cKO right ventricular (RV) myocytes showed increased amplitude and duration of Ca 2+ transients, increased Ca 2+ in the cytoplasm and sarcoplasmic reticulum, increased frequency of spontaneous Ca 2+ release events (sparks) even at comparable sarcoplasmic reticulum load, and dynamic Ca 2+ accumulation in mitochondria. We also observed early- and delayed-after transients in RV myocytes and heightened susceptibility to arrhythmias in Langendorff-perfused hearts. In addition, ryanodine receptor 2 in PKP2cKO-RV cells presented enhanced Ca 2+ sensitivity and preferential phosphorylation in a domain known to modulate Ca 2+ gating. RNAseq at 14 days post-tamoxifen showed no relevant difference in transcript abundance between RV and left ventricle, neither in control nor in PKP2cKO cells. Instead, we found an RV-predominant increase in membrane permeability that can permit Ca 2+ entry into the cell. Connexin 43 ablation mitigated the membrane permeability increase, accumulation of cytoplasmic Ca 2+ , increased frequency of sparks and early stages of RV dysfunction. Connexin 43 hemichannel block with GAP19 normalized [Ca 2+ ] i homeostasis. Similarly, protein kinase C inhibition normalized spark frequency at comparable sarcoplasmic reticulum load levels. Conclusions: Loss of PKP2 creates an RV-predominant arrhythmogenic substrate (Ca 2+ dysregulation) that precedes the cardiomyopathy; this is, at least in part, mediated by a Connexin 43-dependent membrane conduit and repressed by protein kinase C inhibitors. Given that asymmetric Ca 2+ dysregulation precedes the cardiomyopathic stage, we speculate that abnormal Ca 2+ handling in RV myocytes can be a trigger for gross structural changes observed at a later stage.
Databáze: OpenAIRE
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