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Cardiac myocyte

Antonius Baartscheer, Cees A Schumacher, Rob C I Wüst, Jan W T Fiolet, Ger J M Stienen, Ruben Coronel, Coert J Zuurbier
AIMS/HYPOTHESIS: Empagliflozin (EMPA), an inhibitor of the renal sodium-glucose cotransporter (SGLT) 2, reduces the risk of cardiovascular death in patients with type 2 diabetes. The underlying mechanism of this effect is unknown. Elevated cardiac cytoplasmic Na(+) ([Na(+)]c) and Ca(2+) ([Ca(2+)]c) concentrations and decreased mitochondrial Ca(2+) concentration ([Ca(2+)]m) are drivers of heart failure and cardiac death. We therefore hypothesised that EMPA would directly modify [Na(+)]c, [Ca(2+)]c and [Ca(2+)]m in cardiomyocytes...
October 17, 2016: Diabetologia
Richard A Gray, Pras Pathmanathan
Elucidating the underlying mechanisms of fatal cardiac arrhythmias requires a tight integration of electrophysiological experiments, models, and theory. Existing models of transmembrane action potential (AP) are complex (resulting in over parameterization) and varied (leading to dissimilar predictions). Thus, simpler models are needed to elucidate the "minimal physiological requirements" to reproduce significant observable phenomena using as few parameters as possible. Moreover, models have been derived from experimental studies from a variety of species under a range of environmental conditions (for example, all existing rabbit AP models incorporate a formulation of the rapid sodium current, INa, based on 30 year old data from chick embryo cell aggregates)...
October 2016: PLoS Computational Biology
Yao Lu, Honit Piplani, Stacy L McAllister, Carl M Hurt, Eric R Gross
BACKGROUND: Recent evidence suggests that cross talk exists between cellular pathways important for pain signaling and ischemia-reperfusion injury. Here, the authors address whether the transient receptor potential ankyrin 1 (TRPA1) channel, important in pain signaling, is present in cardiac myocytes and regulates cardiac ischemia-reperfusion injury. METHODS: For biochemical analysis of TRPA1, techniques including quantitative polymerase chain reaction, Western blot, and immunofluorescence were used...
September 30, 2016: Anesthesiology
Przemysław B Radwański, Hsiang-Ting Ho, Rengasayee Veeraraghavan, Lucia Brunello, Bin Liu, Andriy E Belevych, Sathya D Unudurthi, Michael A Makara, Silvia G Priori, Pompeo Volpe, Antonis A Armoundas, Wolfgang H Dillmann, Bjorn C Knollmann, Peter J Mohler, Thomas J Hund, Sándor Györke
BACKGROUND: Cardiac arrhythmias are a leading cause of death in the US. Vast majority of these arrhythmias including catecholaminergic polymorphic ventricular tachycardia (CPVT) are associated with increased levels of circulating catecholamines and involve abnormal impulse formation secondary to aberrant Ca(2+) and Na(+) handling. However, the mechanistic link between β-AR stimulation and the subcellular/molecular arrhythmogenic trigger(s) remains elusive. METHODS AND RESULTS: We performed functional and structural studies to assess Ca(2+) and Na(+) signaling in ventricular myocyte as well as surface electrocardiograms in mouse models of cardiac calsequestrin (CASQ2)-associated CPVT...
June 2016: JACC. Basic to Translational Science
Yonggang Zhang, Fang Li, Xiao Xiao, Wu Deng, Chaoran Yin, Ting Zhang, Karnam S Murthy, Wenhui Hu
GATA transcription factors regulate an array of genes important in cell proliferation and differentiation. Here we report the identification of regulator of G protein signaling 4 (RGS4) as a novel target for GATA-6 transcription factor. Although three sites (a, b, c) within the proximal region of rabbit RGS4 promoter for GATA transcription factors were predicted by bioinformatics analysis, only GATA-a site (16 bp from the core TATA box) is essential for RGS4 transcriptional regulation. RT-PCR analysis demonstrated that only GATA-6 was highly expressed in rabbit colonic smooth muscle cells but GATA-4/6 were expressed in cardiac myocytes and GATA-1/2/3 expressed in blood cells...
October 13, 2016: Biochemical and Biophysical Research Communications
Uros Kuzmanov, Hongbo Guo, Diana Buchsbaum, Jake Cosme, Cynthia Abbasi, Ruth Isserlin, Parveen Sharma, Anthony O Gramolini, Andrew Emili
Phospholamban (PLN) plays a central role in Ca(2+) homeostasis in cardiac myocytes through regulation of the sarco(endo)plasmic reticulum Ca(2+)-ATPase 2A (SERCA2A) Ca(2+) pump. An inherited mutation converting arginine residue 9 in PLN to cysteine (R9C) results in dilated cardiomyopathy (DCM) in humans and transgenic mice, but the downstream signaling defects leading to decompensation and heart failure are poorly understood. Here we used precision mass spectrometry to study the global phosphorylation dynamics of 1,887 cardiac phosphoproteins in early affected heart tissue in a transgenic R9C mouse model of DCM compared with wild-type littermates...
October 14, 2016: Proceedings of the National Academy of Sciences of the United States of America
Yohannes Shiferaw
Spontaneous calcium (Ca) waves in cardiac myocytes are known to underlie a wide range of cardiac arrhythmias. However, it is not understood which physiological parameters determine the onset of waves. In this study, we explore the relationship between Ca signaling between ion channels and the nucleation of Ca waves. In particular, we apply a master equation approach to analyze the stochastic interaction between neighboring clusters of ryanodine receptor (RyR) channels. Using this analysis, we show that signaling between clusters can be described as a barrier hopping process with exponential sensitivity to system parameters...
September 2016: Physical Review. E
Shangcheng Xu, Pei Wang, Huiliang Zhang, Guohua Gong, Nicolas Gutierrez Cortes, Weizhong Zhu, Yisang Yoon, Rong Tian, Wang Wang
Mitochondrial permeability transition pore (mPTP) is involved in cardiac dysfunction during chronic β-adrenergic receptor (β-AR) stimulation. The mechanism by which chronic β-AR stimulation leads to mPTP openings is elusive. Here, we show that chronic administration of isoproterenol (ISO) persistently increases the frequency of mPTP openings followed by mitochondrial damage and cardiac dysfunction. Mechanistically, this effect is mediated by phosphorylation of mitochondrial fission protein, dynamin-related protein 1 (Drp1), by Ca(2+)/calmodulin-dependent kinase II (CaMKII) at a serine 616 (S616) site...
October 14, 2016: Nature Communications
Alexandra Pérez-Serra, Rocio Toro, Georgia Sarquella-Brugada, David de Gonzalo-Calvo, Sergi Cesar, Esther Carro, Vicenta Llorente-Cortes, Anna Iglesias, Josep Brugada, Ramon Brugada, Oscar Campuzano
Dilated cardiomyopathy is a rare cardiac disease characterized by left ventricular dilatation and systolic dysfunction leading to heart failure and sudden cardiac death. Currently, despite several conditions have been reported as aetiologies of the disease, a large number of cases remain classified as idiopathic. Recent studies determine that nearly 60% of cases are inherited, therefore due to a genetic cause. Progressive technological advances in genetic analysis have identified over 60 genes associated with this entity, being TTN the main gene, so far...
September 21, 2016: International Journal of Cardiology
Maurizio Pesce, Elisa Messina, Isotta Chimenti, Antonio Paolo Beltrami
The life-long story of the heart starts concomitantly with primary differentiation events occurring in multipotent progenitors located in the so called heart tube. This initially tubular structure starts a looping process which leads to formation of the final four chambered heart with a primary contribution of geometric and position-associated cell sensing. While this establishes the correct patterning of the final cardiac structure, it also feedbacks to fundamental cellular machineries controlling proliferation and differentiation, thus ensuring a coordinated restriction of cell growth and a myocyte terminal differentiation...
October 13, 2016: Stem Cells and Development
Lygia M Malvestio, Mara Rúbia N Celes, Linda A Jelicks, Herbert B Tanowitz, Cibele M Prado
Dystrophin, an important protein of the dystrophin-glycoprotein complex, has been implicated in the pathogenesis of experimental Chagas disease. It is important for the maintenance of cell shape and contraction force transmission. Dystrophin loss has been related to end-stage cardiac myopathies and proposed as a common route for myocardial dysfunction and progression to advanced heart failure. Evidence suggests that calpains, calcium-dependent proteases, digest dystrophin when the calcium concentration is compatible with their activation...
October 11, 2016: Parasitology Research
Ann P Quick, Qiongling Wang, Leonne E Philippen, Giselle Barreto-Torres, David Y Chiang, David L Beavers, Guoliang Wang, Maha Khalid, Julia O Reynolds, Hannah M Campbell, Jordan Showell, Mark D McCauley, Arjen Scholten, Xander H Wehrens
RATIONALE: Junctional membrane complexes (JMC) in myocytes are critical microdomains, in which excitation-contraction coupling occurs. Structural and functional disruption of JMCs underlies contractile dysfunction in failing hearts. However, the role of newly identified JMC protein striated muscle preferentially expressed gene (SPEG) remains unclear. OBJECTIVE: To determine the role of SPEG in healthy and failing adult hearts. MMethods and Results: Proteomic analysis of immunoprecipatated JMC-proteins ryanodine receptor type-2 (RyR2) and junctophilin-2 (JPH2) followed by mass spectrometry identified the serine-threonine kinase SPEG as the only novel binding partner for both proteins...
October 11, 2016: Circulation Research
Constantin von Deuster, Eva Sammut, Liya Asner, David Nordsletten, Pablo Lamata, Christian T Stoeck, Sebastian Kozerke, Reza Razavi
BACKGROUND: The objective of this study is to assess the dynamic alterations of myocardial microstructure and strain between diastole and systole in patients with dilated cardiomyopathy relative to healthy controls using the magnetic resonance diffusion tensor imaging, myocardial tagging, and biomechanical modeling. METHODS AND RESULTS: Dual heart-phase diffusion tensor imaging was successfully performed in 9 patients and 9 controls. Tagging data were acquired for the diffusion tensor strain correction and cardiac motion analysis...
October 2016: Circulation. Cardiovascular Imaging
Shweta R Motiwala, Hanna K Gaggin
Left ventricular remodeling appears to be a critical link between cardiac injury and the development and progression of heart failure with reduced ejection fraction (HFrEF). Several drug and device therapies that modify and reverse the remodeling process in patients with HFrEF are closely associated with improvement in clinical outcomes. Reverse remodeling, including partial or complete recovery of systolic function and structure, is possible but its determinants are incompletely understood. Methods to predict reverse remodeling in response to therapy are not well defined...
October 10, 2016: Current Heart Failure Reports
Bin Yang, Ping Yan, Hui Gong, Lin Zuo, Ying Shi, Jian Guo, Rui Guo, Jun Xie, Bao Li
Myocyte apoptosis is a key determinant of cardiac recovery and prognosis of patients with acute myocardial infarction (AMI). Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK), a member of TNF superfamily, is a pro-inflammatory and pro-angiogenic cytokine implicated in physiological tissue regeneration and wound repair and is closely related to cardiac remodeling, dysfunction and fibrosis. However, the role of TWEAK and its receptor Fn14 in the cardiomyocyte apoptosis is still poorly understood...
2016: American Journal of Translational Research
Christian Faul
Fibroblast growth factors (FGF) are mitogenic signal mediators that induce cell proliferation and survival. Although cardiac myocytes are post-mitotic, they have been shown to be able to respond to local and circulating FGFs. While precise molecular mechanisms are not well characterized, some FGF family members have been shown to induce cardiac remodeling under physiologic conditions by mediating hypertrophic growth in cardiac myocytes and by promoting angiogenesis, both events leading to increased cardiac function and output...
October 7, 2016: Bone
Yi Li, Xiaoli Shi, Lei Tian, Hongyu Sun, Yujing Wu, Xia Li, Jianjun Li, Yujie Wei, Xinxiao Han, Jiao Zhang, Xiaowei Jia, Rui Bai, Limin Jing, Peng Ding, Huiliang Liu, Dong Han
A schematic for the mechanism of accelerating the assembly of intercalated discs (IDs) in cardiac myocytes regulated by gold nanoparticles (AuNPs) is presented. AuNPs with local nanoscale stiffness in the substrate activate β1-integrin signaling, which mediates the activation of integrin-linked kinase (ILK) and its downstream signal kinase by stimulating expression of the transcription factors GATA4 and MEF-2c.
October 10, 2016: Advanced Materials
Sean D Boothe, Jackson D Myers, Seokwon Pok, Junping Sun, Yutao Xi, Raymond M Nieto, Jie Cheng, Jeffrey G Jacot
The stiffness of myocardial tissue changes significantly at birth and during neonatal development, concurrent with significant changes in contractile and electrical maturation of cardiomyocytes. Previous studies by our group have shown that cardiomyocytes generate maximum contractile force when cultured on a substrate with a stiffness approximating native cardiac tissue. However, effects of substrate stiffness on the electrophysiology and ion currents in cardiomyocytes have not been fully characterized. In this study, neonatal rat ventricular myocytes were cultured on the surface of flat polyacrylamide hydrogels with elastic moduli ranging from 1 to 25 kPa...
October 8, 2016: Cell Biochemistry and Biophysics
Lihua Qi, Yu Yu, Xiaochun Chi, Danyu Lu, Yao Song, Youyi Zhang, Hongquan Zhang
Kindlin-2, a member of the Kindlin family focal adhesion proteins, plays an important role in cardiac development. It is known that defects in the Z-disc proteins lead to hypertrophic cardiomyopathy (HCM) or dilated cardiomyopathy (DCM). Our previous investigation showed that Kindlin-2 is mainly localized at the Z-disc and depletion of Kindlin-2 disrupts the structure of the Z-Disc. Here, we reported that depletion of Kindlin-2 leads to the disordered myocardial fibers, fractured and vacuolar degeneration in myocardial fibers...
September 20, 2016: Science China. Life Sciences
Ilka Lorenzen-Schmidt, Samantha B Clarke, W Glen Pyle
Cardiac myofilaments act as the central contractile apparatus of heart muscle cells. Covalent modification of constituent proteins through phosphorylation is a rapid and powerful mechanism to control myofilament function, and is increasingly seen as a mechanism of disease. While the relationship between protein kinases and cardiac myofilaments has been widely examined, the impact of protein dephosphorylation by protein phosphatases is poorly understood. This review outlines the mechanisms by which the mostly widely expressed protein phosphatases in cardiac myocytes regulate myofilament function, and the emerging role of myofilament-associated protein phosphatases in heart failure...
October 6, 2016: Journal of Molecular and Cellular Cardiology
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