@article{MaurerHartmannArgyriouetal.2022,
  author    = {Maurer, Wiebke and Hartmann, Nico and Argyriou, Loukas and Sossalla, Samuel and Streckfuss-B{\"o}meke, Katrin},
  title     = {Generation of homozygous Na\(_{v}\)1.8 knock-out iPSC lines by CRISPR Cas9 genome editing to investigate a potential new antiarrhythmic strategy},
  series = {Stem Cell Research},
  volume    = {60},
  journal   = {Stem Cell Research},
  doi       = {10.1016/j.scr.2022.102677},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300936},
  year      = {2022},
  abstract  = {The sodium channel Na\(_{v}\)1.8, encoded by SCN10A, is reported to contribute to arrhythmogenesis by inducing the late I\(_{Na}\) and thereby enhanced persistent Na\(^{+}\) current. However, its exact electrophysiological role in cardiomyocytes remains unclear. Here, we generated induced pluripotent stem cells (iPSCs) with a homozygous SCN10A knock-out from a healthy iPSC line by CRISPR Cas9 genome editing. The edited iPSCs maintained full pluripotency, genomic integrity, and spontaneous in vitro differentiation capacity. The iPSCs are able to differentiate into iPSC-cardiomyocytes, hence making it possible to investigate the role of Na\(_{v}\)1.8 in the heart.},
  language  = {en}
}
@article{WagnerSadekDybkovaetal.2021,
  author    = {Wagner, Michael and Sadek, Mirna S. and Dybkova, Nataliya and Mason, Fleur E. and Klehr, Johann and Firneburg, Rebecca and Cachorro, Eleder and Richter, Kurt and Klapproth, Erik and Kuenzel, Stephan R. and Lorenz, Kristina and Heijman, Jordi and Dobrev, Dobromir and El-Armouche, Ali and Sossalla, Samuel and K{\"a}mmerer, Susanne},
  title     = {Cellular mechanisms of the anti-arrhythmic effect of cardiac PDE2 overexpression},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {9},
  issn      = {1422-0067},
  doi       = {10.3390/ijms22094816},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285888},
  year      = {2021},
  abstract  = {Background: Phosphodiesterases (PDE) critically regulate myocardial cAMP and cGMP levels. PDE2 is stimulated by cGMP to hydrolyze cAMP, mediating a negative crosstalk between both pathways. PDE2 upregulation in heart failure contributes to desensitization to β-adrenergic overstimulation. After isoprenaline (ISO) injections, PDE2 overexpressing mice (PDE2 OE) were protected against ventricular arrhythmia. Here, we investigate the mechanisms underlying the effects of PDE2 OE on susceptibility to arrhythmias. Methods: Cellular arrhythmia, ion currents, and Ca\(^{2+}\)-sparks were assessed in ventricular cardiomyocytes from PDE2 OE and WT littermates. Results: Under basal conditions, action potential (AP) morphology were similar in PDE2 OE and WT. ISO stimulation significantly increased the incidence of afterdepolarizations and spontaneous APs in WT, which was markedly reduced in PDE2 OE. The ISO-induced increase in I\(_{CaL}\) seen in WT was prevented in PDE2 OE. Moreover, the ISO-induced, Epac- and CaMKII-dependent increase in I\(_{NaL}\) and Ca\(^{2+}\)-spark frequency was blunted in PDE2 OE, while the effect of direct Epac activation was similar in both groups. Finally, PDE2 inhibition facilitated arrhythmic events in ex vivo perfused WT hearts after reperfusion injury. Conclusion: Higher PDE2 abundance protects against ISO-induced cardiac arrhythmia by preventing the Epac- and CaMKII-mediated increases of cellular triggers. Thus, activating myocardial PDE2 may represent a novel intracellular anti-arrhythmic therapeutic strategy in HF.},
  language  = {en}
}
@article{BuddeHassounTangosetal.2021,
  author    = {Budde, Heidi and Hassoun, Roua and Tangos, Melina and Zhazykbayeva, Saltanat and Herwig, Melissa and Varatnitskaya, Marharyta and Sieme, Marcel and Delalat, Simin and Sultana, Innas and Kolijn, Detmar and G{\"o}m{\"o}ri, Kamilla and Jarkas, Muhammad and L{\´o}di, M{\´a}ria and Jaquet, Kornelia and Kov{\´a}cs, {\´A}rp{\´a}d and Mannherz, Hans Georg and Sequeira, Vasco and M{\"u}gge, Andreas and Leichert, Lars I. and Sossalla, Samuel and Hamdani, Nazha},
  title     = {The interplay between S-glutathionylation and phosphorylation of cardiac troponin I and myosin binding protein C in end-stage human failing hearts},
  series = {Antioxidants},
  volume    = {10},
  journal   = {Antioxidants},
  number    = {7},
  issn      = {2076-3921},
  doi       = {10.3390/antiox10071134},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-242701},
  year      = {2021},
  abstract  = {Oxidative stress is defined as an imbalance between the antioxidant defense system and the production of reactive oxygen species (ROS). At low levels, ROS are involved in the regulation of redox signaling for cell protection. However, upon chronical increase in oxidative stress, cell damage occurs, due to protein, DNA and lipid oxidation. Here, we investigated the oxidative modifications of myofilament proteins, and their role in modulating cardiomyocyte function in end-stage human failing hearts. We found altered maximum Ca\(^{2+}\)-activated tension and Ca\(^{2+}\) sensitivity of force production of skinned single cardiomyocytes in end-stage human failing hearts compared to non-failing hearts, which was corrected upon treatment with reduced glutathione enzyme. This was accompanied by the increased oxidation of troponin I and myosin binding protein C, and decreased levels of protein kinases A (PKA)- and C (PKC)-mediated phosphorylation of both proteins. The Ca\(^{2+}\) sensitivity and maximal tension correlated strongly with the myofilament oxidation levels, hypo-phosphorylation, and oxidative stress parameters that were measured in all the samples. Furthermore, we detected elevated titin-based myocardial stiffness in HF myocytes, which was reversed by PKA and reduced glutathione enzyme treatment. Finally, many oxidative stress and inflammation parameters were significantly elevated in failing hearts compared to non-failing hearts, and corrected upon treatment with the anti-oxidant GSH enzyme. Here, we provide evidence that the altered mechanical properties of failing human cardiomyocytes are partially due to phosphorylation, S-glutathionylation, and the interplay between the two post-translational modifications, which contribute to the development of heart failure.},
  language  = {en}
}
@article{EiringhausWuenscheTirilomisetal.2020,
  author    = {Eiringhaus, J{\"o}rg and W{\"u}nsche, Christoph M. and Tirilomis, Petros and Herting, Jonas and Bork, Nadja and Nikolaev, Viacheslav O. and Hasenfuss, Gerd and Sossalla, Samuel and Fischer, Thomas H.},
  title     = {Sacubitrilat reduces pro-arrhythmogenic sarcoplasmic reticulum Ca\(^{2+}\) leak in human ventricular cardiomyocytes of patients with end-stage heart failure},
  series = {ESC Heart Failure},
  volume    = {7},
  journal   = {ESC Heart Failure},
  number    = {5},
  doi       = {10.1002/ehf2.12918},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218479},
  pages     = {2992 -- 3002},
  year      = {2020},
  abstract  = {Aims Inhibition of neprilysin and angiotensin II receptor by sacubitril/valsartan (Val) (LCZ696) reduces mortality in heart failure (HF) patients compared with sole inhibition of renin-angiotensin system. Beneficial effects of increased natriuretic peptide levels upon neprilysin inhibition have been proposed, whereas direct effects of sacubitrilat (Sac) (LBQ657) on myocardial Ca\(^{2+}\) cycling remain elusive. Methods and results Confocal microscopy (Fluo-4 AM) was used to investigate pro-arrhythmogenic sarcoplasmic reticulum (SR) Ca\(^{2+}\) leak in freshly isolated murine and human ventricular cardiomyocytes (CMs) upon Sac (40 μmol/L)/Val (13 μmol/L) treatment. The concentrations of Sac and Val equalled plasma concentrations of LCZ696 treatment used in PARADIGM-HF trial. Epifluorescence microscopy measurements (Fura-2 AM) were performed to investigate effects on systolic Ca\(^{2+}\) release, SR Ca\(^{2+}\) load, and Ca\(^{2+}\)-transient kinetics in freshly isolated murine ventricular CMs. The impact of Sac on myocardial contractility was evaluated using in toto-isolated, isometrically twitching ventricular trabeculae from human hearts with end-stage HF. Under basal conditions, the combination of Sac/Val did not influence diastolic Ca\(^{2+}\)-spark frequency (CaSpF) nor pro-arrhythmogenic SR Ca\(^{2}\) leak in isolated murine ventricular CMs (n CMs/hearts = 80/7 vs. 100/7, P = 0.91/0.99). In contrast, Sac/Val treatment reduced CaSpF by 35 ± 9\% and SR Ca\(^{2+}\) leak by 45 ± 9\% in CMs put under catecholaminergic stress (isoproterenol 30 nmol/L, n = 81/7 vs. 62/7, P < 0.001 each). This could be attributed to Sac, as sole Sac treatment also reduced both parameters by similar degrees (reduction of CaSpF by 57 ± 7\% and SR Ca2+ leak by 76 ± 5\%; n = 101/4 vs. 108/4, P < 0.01 each), whereas sole Val treatment did not. Systolic Ca2+ release, SR Ca\(^{2+}\) load, and Ca\(^{2+}\)-transient kinetics including SERCA activity (k\(_{SERCA}\)) were not compromised by Sac in isolated murine CMs (n = 41/6 vs. 39/6). Importantly, the combination of Sac/Val and Sac alone also reduced diastolic CaSpF and SR Ca\(^{2+}\) leak (reduction by 74 ± 7\%) in human left ventricular CMs from patients with end-stage HF (n = 71/8 vs. 78/8, P < 0.05 each). Myocardial contractility of human ventricular trabeculae was not acutely affected by Sac treatment as the developed force remained unchanged over a time course of 30 min (n trabeculae/hearts = 3/3 vs. 4/3). Conclusion This study demonstrates that neprilysin inhibitor Sac directly improves Ca\(^{2+}\) homeostasis in human end-stage HF by reducing pro-arrhythmogenic SR Ca\(^{2+}\) leak without acutely affecting systolic Ca\(^{2+}\) release and inotropy. These effects might contribute to the mortality benefits observed in the PARADIGM-HF trial.},
  language  = {en}
}