Cardiovascular diseases are associated with an altered cardiomyocyte metabolism. Because of a shortage of human heart tissue, experimental studies mostly rely on alternative approaches including animal and cell culture models. Since the use of isolated primary cardiomyocytes is limited, immortalized cardiomyocyte cell lines may represent a useful tool as they closely mimic human cardiomyocytes. This study is focused on the AC16 cell line generated from adult human ventricular cardiomyocytes. Despite an increasing number of studies employing AC16 cells, a comprehensive proteomic, bioenergetic, and oxygen-sensing characterization of proliferating vs. differentiated cells is still lacking. Here, we provide a comparison of these two stages, particularly emphasizing cell metabolism, mitochondrial function, and hypoxic signaling. Label-free quantitative mass spectrometry revealed a decrease in autophagy and cytoplasmic translation in differentiated AC16, confirming their phenotype. Cell differentiation led to global increase in mitochondrial proteins [e.g. oxidative phosphorylation (OXPHOS) proteins, TFAM, VWA8] reflected by elevated mitochondrial respiration. Fatty acid oxidation proteins were increased in differentiated cells, whereas the expression levels of proteins associated with fatty acid synthesis were unchanged and glycolytic proteins were decreased. There was a profound difference between proliferating and differentiated cells in their response to hypoxia and anoxia-reoxygenation. We conclude that AC16 differentiation leads to proteomic and metabolic shifts and altered cell response to oxygen deprivation. This underscores the requirement for proper selection of the particular differentiation state during experimental planning.NEW & NOTEWORTHY Proliferating and differentiated AC16 cell lines exhibit distinct proteomic and metabolic profiles with critical implications for experimental design. Proliferating cells predominantly utilize glycolysis and are highly sensitive to hypoxia, whereas differentiated cells display enhanced mitochondrial biogenesis, oxidative phosphorylation, and resistance to anoxia-reoxygenation. These findings provide novel insights into the metabolic adaptations during differentiation and highlight the necessity of selecting the appropriate cellular stage to ensure accurate experimental outcomes.

• Klíčová slova
• AC16, differentiation, hypoxia, metabolism, mitochondria,
• MeSH
• buněčná diferenciace * fyziologie   MeSH
• buněčné linie MeSH
• energetický metabolismus MeSH
• hypoxie buňky fyziologie   MeSH
• kardiomyocyty * metabolismus   MeSH
• lidé MeSH
• mitochondriální proteiny metabolismus   MeSH
• mitochondrie * metabolismus   MeSH
• oxidativní fosforylace MeSH
• proliferace buněk MeSH
• proteomika metody   MeSH
• signální transdukce * fyziologie   MeSH
• srdeční mitochondrie * metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• mitochondriální proteiny MeSH

AIMS: The cardiac conduction system (CCS) is progressively specified during development by interactions among a discrete number of transcription factors (TFs) that ensure its proper patterning and the emergence of its functional properties. Meis genes encode homeodomain TFs with multiple roles in mammalian development. In humans, Meis genes associate with congenital cardiac malformations and alterations of cardiac electrical activity; however, the basis for these alterations has not been established. Here, we studied the role of Meis TFs in cardiomyocyte development and function during mouse development and adult life. METHODS AND RESULTS: We studied Meis1 and Meis2 conditional deletion mouse models that allowed cardiomyocyte-specific elimination of Meis function during development and inducible elimination of Meis function in cardiomyocytes of the adult CCS. We studied cardiac anatomy, contractility, and conduction. We report that Meis factors are global regulators of cardiac conduction, with a predominant role in the CCS. While constitutive Meis deletion in cardiomyocytes led to congenital malformations of the arterial pole and atria, as well as defects in ventricular conduction, Meis elimination in cardiomyocytes of the adult CCS produced sinus node dysfunction and delayed atrio-ventricular conduction. Molecular analyses unravelled Meis-controlled molecular pathways associated with these defects. Finally, we studied in transgenic mice the activity of a Meis1 human enhancer related to an single-nucleotide polymorphism (SNP) associated by Genome-wide association studies (GWAS) to PR (P and R waves of the electrocardiogram) elongation and found that the transgene drives expression in components of the atrio-ventricular conduction system. CONCLUSION: Our study identifies Meis TFs as essential regulators of the establishment of cardiac conduction function during development and its maintenance during adult life. In addition, we generated animal models and identified molecular alterations that will ease the study of Meis-associated conduction defects and congenital malformations in humans.

• Klíčová slova
• Cardiac development, Mouse targeted mutation, PR elongation, Sinus node dysfunction, Transcription factor,
• MeSH
• akční potenciály MeSH
• fenotyp MeSH
• homeodoménové proteiny * genetika   metabolismus   MeSH
• kardiomyocyty * metabolismus   patologie   MeSH
• kontrakce myokardu MeSH
• myši knockoutované MeSH
• nodus sinuatrialis metabolismus   patofyziologie   MeSH
• převodní systém srdeční * metabolismus   patofyziologie   růst a vývoj   MeSH
• srdeční arytmie patofyziologie   metabolismus   genetika   MeSH
• srdeční frekvence * MeSH
• transkripční faktor Meis1 * genetika   metabolismus   nedostatek   MeSH
• věkové faktory MeSH
• vrozené srdeční vady metabolismus   genetika   patofyziologie   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• homeodoménové proteiny * MeSH
• Meis1 protein, mouse MeSH Prohlížeč
• transkripční faktor Meis1 * MeSH

Fibroblast growth factor 21 (FGF21), a metabolic hormone with pleiotropic effects, is beneficial for various cardiac disorders. However, FGF21's role in heart failure with preserved ejection fraction (HFpEF) remains unclear. Here, we show that elevated circulating FGF21 levels are negatively associated with cardiac diastolic function in patients with HFpEF. Global or adipose FGF21 deficiency exacerbates cardiac diastolic dysfunction and damage in high-fat diet (HFD) plus N[w]-nitro-L-arginine methyl ester (L-NAME)-induced HFpEF mice, whereas these effects are notably reversed by FGF21 replenishment. Mechanistically, FGF21 enhances the production of adiponectin (APN), which in turn indirectly acts on cardiomyocytes, or FGF21 directly targets cardiomyocytes, to negatively regulate pyruvate dehydrogenase kinase 4 (PDK4) production by activating PI3K/AKT signals, then promoting mitochondrial bioenergetics. Additionally, APN deletion strikingly abrogates FGF21's protective effects against HFpEF, while genetic PDK4 inactivation markedly mitigates HFpEF in mice. Thus, FGF21 protects against HFpEF via fine-tuning the multiorgan crosstalk among the adipose, liver, and heart.

• MeSH
• adiponektin metabolismus   genetika   MeSH
• dieta s vysokým obsahem tuků škodlivé účinky   MeSH
• energetický metabolismus * MeSH
• fibroblastové růstové faktory * metabolismus   genetika   krev   MeSH
• fosfatidylinositol-3-kinasy metabolismus   MeSH
• játra metabolismus   MeSH
• kardiomyocyty metabolismus   MeSH
• lidé MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• PDH-kinasa metabolismus   genetika   MeSH
• protoonkogenní proteiny c-akt metabolismus   MeSH
• signální transdukce MeSH
• srdeční mitochondrie * metabolismus   MeSH
• srdeční selhání * metabolismus   patofyziologie   genetika   MeSH
• tepový objem MeSH
• tuková tkáň metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adiponektin MeSH
• FGF21 protein, human MeSH Prohlížeč
• fibroblast growth factor 21 MeSH Prohlížeč
• fibroblastové růstové faktory * MeSH
• fosfatidylinositol-3-kinasy MeSH
• PDH-kinasa MeSH
• Pdk4 protein, mouse MeSH Prohlížeč
• protoonkogenní proteiny c-akt MeSH

Hypertrophic cardiomyopathy (HCM) caused by autosomal-dominant mutations in genes coding for structural sarcomeric proteins, is the most common inherited heart disease. HCM is associated with myocardial hypertrophy, fibrosis and ventricular dysfunction. Hypoxia-inducible transcription factor-1α (Hif-1α) is the central master regulators of cellular hypoxia response and associated with HCM. Yet its exact role remains to be elucidated. Therefore, the effect of a cardiomyocyte-specific Hif-1a knockout (cHif1aKO) was studied in an established α-MHC719/+ HCM mouse model that exhibits the classical features of human HCM. The results show that Hif-1α protein and HIF targets were upregulated in left ventricular tissue of α-MHC719/+ mice. Cardiomyocyte-specific abolishment of Hif-1a blunted the disease phenotype, as evidenced by decreased left ventricular wall thickness, reduced myocardial fibrosis, disordered SRX/DRX state and ROS production. cHif1aKO induced normalization of pro-hypertrophic and pro-fibrotic left ventricular remodeling signaling evidenced on whole transcriptome and proteomics analysis in α-MHC719/+ mice. Proteomics of serum samples from patients with early onset HCM revealed significant modulation of HIF. These results demonstrate that HIF signaling is involved in mouse and human HCM pathogenesis. Cardiomyocyte-specific knockout of Hif-1a attenuates disease phenotype in the mouse model. Targeting Hif-1α might serve as a therapeutic option to mitigate HCM disease progression.

• Klíčová slova
• HIF1A, Hypertrophic cardiomyopathy, Hypertrophy, Hypoxia, Myocardial fibrosis,
• MeSH
• faktor 1 indukovatelný hypoxií - podjednotka alfa * metabolismus   genetika   MeSH
• fibróza MeSH
• hypertrofická kardiomyopatie * metabolismus   patologie   genetika   MeSH
• kardiomyocyty metabolismus   patologie   MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• myši knockoutované MeSH
• myši MeSH
• sarkomery * metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• faktor 1 indukovatelný hypoxií - podjednotka alfa * MeSH
• Hif1a protein, mouse MeSH Prohlížeč

The global COVID-19 pandemic, caused by SARS-CoV-2, has led to significant morbidity and mortality, with a profound impact on cardiovascular health. This review investigates the mechanisms of SARS-CoV-2's interaction with cardiac tissue, particularly emphasizing the role of the Spike protein and ACE2 receptor in facilitating viral entry and subsequent cardiac complications. We dissect the structural features of the virus, its interactions with host cell receptors, and the resulting pathophysiological changes in the heart. Highlighting SARS-CoV-2's broad organ tropism, especially its effects on cardiomyocytes via ACE2 and TMPRSS2, the review addresses how these interactions exacerbate cardiovascular issues in patients with pre-existing conditions such as diabetes and hypertension. Additionally, we assess both direct and indirect mechanisms of virus-induced cardiac damage, including myocarditis, arrhythmias, and long-term complications such as 'long COVID'. This review underscores the complexity of SARS-CoV-2's impact on the heart, emphasizing the need for ongoing research to fully understand its long-term effects on cardiovascular health. Key words: COVID-19, Heart, ACE2, Spike protein, Cardiomyocytes, Myocarditis, Long COVID.

• MeSH
• angiotensin-konvertující enzym 2 metabolismus   MeSH
• COVID-19 * metabolismus   komplikace   virologie   epidemiologie   MeSH
• glykoprotein S, koronavirus * metabolismus   MeSH
• internalizace viru MeSH
• kardiomyocyty virologie   metabolismus   MeSH
• lidé MeSH
• nemoci srdce * virologie   metabolismus   MeSH
• SARS-CoV-2 * patogenita   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• ACE2 protein, human MeSH Prohlížeč
• angiotensin-konvertující enzym 2 MeSH
• glykoprotein S, koronavirus * MeSH
• spike protein, SARS-CoV-2 MeSH Prohlížeč

Coronary heart disease (CHD) is one of the most commonly seen cardiovascular conditions across the globe. Junctional cadherin 5 associated (JCAD) protein is found in the intercellular junctions of endothelial cells and linked to cardiovascular diseases. Nonetheless, the influence of JCAD on cardiomyocyte injury caused by CHD is unclear. A model of H2O2-induced H9c2 cell injury was constructed, and JCAD mRNA and protein levels were assessed by qRT-PCR and Western blot. The impacts of JCAD on the proliferation or apoptosis of H9c2 cells were explored by CCK-8 assay, Western blot and TUNEL staining. The effect of JCAD on the inflammatory response and vascular endothelial function of H9c2 cells was detected using ELISA kits. The levels of Wnt/β-catenin pathway-related proteins were assessed by Western blot. H2O2 treatment led to a rise in the levels of JCAD in H9c2 cells. Over-expression of JCAD promoted H2O2-induced cellular injury, leading to notably elevated contents of inflammatory factors, along with vascular endothelial dysfunction. In contrast to over-expression of JCAD, silencing of JCAD attenuated H2O2-induced cellular injury and inhibited apoptosis, inflammatory response and vascular endothelial dysfunction. Notably, JCAD could regulate the Wnt/β-catenin pathway, while DKK-1, Wnt/β-catenin pathway antagonist, counteracted the enhancing impact of JCAD over-expression on H2O2-induced H9c2 cell injury, further confirming that JCAD acts by regulating the Wnt/β-catenin pathway. In summary, over-expression of JCAD promoted H2O2-induced H9c2 cell injury by activating the Wnt/β-catenin pathway, while silencing of JCAD attenuated the H2O2-induced cell injury.

• Klíčová slova
• JCAD, Wnt/β-catenin signalling pathway, coronary heart disease, inflammation, vascular endothelial function,
• MeSH
• apoptóza * účinky léků   MeSH
• beta-katenin metabolismus   MeSH
• buněčné linie MeSH
• down regulace * účinky léků   MeSH
• kadheriny metabolismus   MeSH
• kardiomyocyty * metabolismus   účinky léků   MeSH
• krysa rodu Rattus MeSH
• peroxid vodíku * farmakologie   MeSH
• proliferace buněk účinky léků   MeSH
• signální dráha Wnt * účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• beta-katenin MeSH
• kadheriny MeSH
• peroxid vodíku * MeSH

Aminophylline, a bronchodilator mainly used to treat severe asthma attacks, may induce arrhythmias. Unfortunately, the underlying mechanism is not well understood. We have recently described a significant, on average inhibitory effect of aminophylline on inward rectifier potassium current IK1, known to substantially contribute to arrhythmogenesis, in rat ventricular myocytes at room temperature. This study was aimed to examine whether a similar effect may be observed under clinically relevant conditions. Experiments were performed using the whole cell patch clamp technique at 37°C on enzymatically isolated healthy porcine and failing human ventricular myocytes. The effect of clinically relevant concentrations of aminophylline (10-100 µM) on IK1 did not significantly differ in healthy porcine and failing human ventricular myocytes. IK1 was reversibly inhibited by ∼20 and 30 % in the presence of 30 and 100 µM aminophylline, respectively, at -110 mV; an analogical effect was observed at -50 mV. To separate the impact of IK1 changes on AP configuration, potentially interfering ionic currents were blocked (L-type calcium and delayed rectifier potassium currents). A significant prolongation of AP duration was observed in the presence of 100 µM aminophylline in porcine cardiomyocytes which well agreed with the effect of a specific IK1 inhibitor Ba2+ (10 µM) and with the result of simulations using a porcine ventricular cell model. We conclude that the observed effect of aminophylline on healthy porcine and failing human IK1 might be involved in its proarrhythmic action. To fully understand the underlying mechanism, potential aminophylline impact on other ionic currents should be explored.

• Klíčová slova
• Action potential, Aminophylline, Arrhythmia, Human, Inward rectifier, Pig,
• MeSH
• akční potenciály účinky léků   MeSH
• aminofylin * farmakologie   MeSH
• draslíkové kanály dovnitř usměrňující * metabolismus   MeSH
• kardiomyocyty * účinky léků   metabolismus   MeSH
• lidé MeSH
• metoda terčíkového zámku MeSH
• prasata MeSH
• srdeční komory účinky léků   metabolismus   MeSH
• srdeční selhání metabolismus   farmakoterapie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aminofylin * MeSH
• draslíkové kanály dovnitř usměrňující * MeSH

Alterations in ion channel expression and function known as "electrical remodeling" contribute to the development of hypertrophy and to the emergence of arrhythmias and sudden cardiac death. However, comparing current density values - an electrophysiological parameter commonly utilized to assess ion channel function - between normal and hypertrophied cells may be flawed when current amplitude does not scale with cell size. Even more, common routines to study equally sized cells or to discard measurements when large currents do not allow proper voltage-clamp control may introduce a selection bias and thereby confound direct comparison. To test a possible dependence of current density on cell size and shape, we employed whole-cell patch-clamp recording of voltage-gated sodium and calcium currents in Langendorff-isolated ventricular cardiomyocytes and Purkinje myocytes, as well as in cardiomyocytes derived from trans-aortic constriction operated mice. Here, we describe a distinct inverse relationship between voltage-gated sodium and calcium current densities and cell capacitance both in normal and hypertrophied cells. This inverse relationship was well fit by an exponential function and may be due to physiological adaptations that do not scale proportionally with cell size or may be explained by a selection bias. Our study emphasizes the need to consider cell size bias when comparing current densities in cardiomyocytes of different sizes, particularly in hypertrophic cells. Conventional comparisons based solely on mean current density may be inadequate for groups with unequal cell size or non-proportional current amplitude and cell size scaling.

• Klíčová slova
• L-type calcium and sodium current density, Ventricular and Purkinje myocyte, bias, cell capacitance, cell size, trans-aortic constriction induced hypertrophy,
• MeSH
• kardiomegalie * metabolismus   patologie   MeSH
• kardiomyocyty * metabolismus   patologie   MeSH
• metoda terčíkového zámku MeSH
• myši MeSH
• velikost buňky * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The combination of aminophylline and salbutamol is frequently used in clinical practice in the treatment of obstructive lung diseases. While the side effects (including arrhythmias) of the individual bronchodilator drugs were well described previously, the side effects of combined treatment are almost unknown. We aimed to study the arrhythmogenic potential of combined aminophylline and salbutamol treatment in vitro. For this purpose, we used the established atomic force microscopy (AFM) model coupled with cardiac organoids derived from human pluripotent stem cells (hPSC-CMs). We focused on the chronotropic, inotropic, and arrhythmogenic effects of salbutamol alone and aminophylline and salbutamol combined treatment. We used a method based on heart rate/beat rate variability (HRV/BRV) analysis to detect arrhythmic events in the hPSC-CM based AFM recordings. Salbutamol and aminophylline had a synergistic chronotropic and inotropic effect compared to the effects of monotherapy. Our main finding was that salbutamol reduced the arrhythmogenic effect of aminophylline, most likely mediated by endothelial nitric oxide synthase activated by beta-2 adrenergic receptors. These findings were replicated and confirmed using hPSC-CM derived from two cell lines (CCTL4 and CCTL12). Data suggest that salbutamol as an add-on therapy may not only deliver a bronchodilator effect but also increase the cardiovascular safety of aminophylline, as salbutamol reduces its arrhythmogenic potential.

• Klíčová slova
• Aminophylline, Arrhythmogenic effects, Atomic force microscopy, iPSC, Biomechanical properties, Cardiomyocytes, Drug cardiotoxicity, HESC, Pulmonary drug screening, Salbutamol,
• MeSH
• albuterol * farmakologie   MeSH
• aminofylin * farmakologie   MeSH
• bronchodilatancia farmakologie   MeSH
• buněčné linie MeSH
• kardiomyocyty účinky léků   metabolismus   MeSH
• lidé MeSH
• mikroskopie atomárních sil MeSH
• pluripotentní kmenové buňky účinky léků   cytologie   MeSH
• srdeční arytmie * farmakoterapie   MeSH
• srdeční frekvence účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• albuterol * MeSH
• aminofylin * MeSH
• bronchodilatancia MeSH

Cardiac fibrosis occurs following insults to the myocardium and is characterized by the abnormal accumulation of non-compliant extracellular matrix (ECM), which compromises cardiomyocyte contractile activity and eventually leads to heart failure. This phenomenon is driven by the activation of cardiac fibroblasts (cFbs) to myofibroblasts and results in changes in ECM biochemical, structural and mechanical properties. The lack of predictive in vitro models of heart fibrosis has so far hampered the search for innovative treatments, as most of the cellular-based in vitro reductionist models do not take into account the leading role of ECM cues in driving the progression of the pathology. Here, we devised a single-step decellularization protocol to obtain and thoroughly characterize the biochemical and micro-mechanical properties of the ECM secreted by activated cFbs differentiated from human induced pluripotent stem cells (iPSCs). We activated iPSC-derived cFbs to the myofibroblast phenotype by tuning basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-β1) signalling and confirmed that activated cells acquired key features of myofibroblast phenotype, like SMAD2/3 nuclear shuttling, the formation of aligned alpha-smooth muscle actin (α-SMA)-rich stress fibres and increased focal adhesions (FAs) assembly. Next, we used Mass Spectrometry, nanoindentation, scanning electron and confocal microscopy to unveil the characteristic composition and the visco-elastic properties of the abundant, collagen-rich ECM deposited by cardiac myofibroblasts in vitro. Finally, we demonstrated that the fibrotic ECM activates mechanosensitive pathways in iPSC-derived cardiomyocytes, impacting on their shape, sarcomere assembly, phenotype, and calcium handling properties. We thus propose human bio-inspired decellularized matrices as animal-free, isogenic cardiomyocyte culture substrates recapitulating key pathophysiological changes occurring at the cellular level during cardiac fibrosis.

• Klíčová slova
• Cardiac fibrosis modelling, Decellularized extracellular matrix, Induced pluripotent stem cells, iPSC-derived-cardiac fibroblasts, iPSC-derived-cardiomyocytes,
• MeSH
• buněčná diferenciace MeSH
• extracelulární matrix * metabolismus   MeSH
• fenotyp * MeSH
• fibróza * MeSH
• indukované pluripotentní kmenové buňky * metabolismus   MeSH
• kardiomyocyty * metabolismus   patologie   MeSH
• lidé MeSH
• myofibroblasty patologie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH