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https://www.readbyqxmd.com/read/29132927/whole-exome-sequencing-identified-a-pathogenic-mutation-in-ryr2-in-a-chinese-family-with-unexplained-sudden-death
#1
Yubi Lin, Siqi He, Zili Liao, Ruiling Feng, Ruilin Liu, Yongzheng Peng, Nan Yu, Hang Qi, Jia Chen, Zifeng Huang, Heping Lei, Yang Liu, Fang Rao, Chunyu Deng, Yumei Xue, Guolin Zhang, Bin Zhang, Hua Yao, Shulin Wu
OBJECTIVE: This study aimed to identify the pathogenic mutation in a Chinese family with unexplained sudden death (USD) or occasional syncope. MATERIALS AND METHODS: Whole exome sequencing and target capture sequencing were respectively conducted for two related patients. The genetic data was screened using the 1000 genomes project and SNP database (PubMed), and the identified mutations were assessed for predicted pathogenicity using the SIFT and Polyphen-2 algorithms...
October 10, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/29131945/enantioselectivity-of-2-2-3-5-6-pentachlorobiphenyl-pcb-95-atropisomers-toward-ryanodine-receptors-ryrs-and-their-influences-on-hippocampal-neuronal-networks
#2
Wei Feng, Jing Zheng, Gaelle Robin, Yao Dong, Makoto Ichikawa, Yoshihisa Inoue, Tadashi Mori, Takeshi Nakano, Isaac N Pessah
Nineteen ortho-substituted PCBs are chiral and found enantioselectively enriched in ecosystems. Their differential actions on biological targets are not understood. PCB 95 (2,2',3,5',6-pentachlorobiphenyl), a chiral PCB of current environmental relevance, is among the most potent towards modifying ryanodine receptors (RyR) function and Ca2+ signaling. PCB 95 atropisomers are separated and assigned aR- and aS-PCB 95 using 3 chiral-columns HPLC and circular dichroism spectroscopy. Studies of RyR1-enriched microsomes show aR-PCB 95 with >4X greater potency (EC50=0...
November 13, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29131158/ucp1-independent-signaling-involving-serca2b-mediated-calcium-cycling-regulates-beige-fat-thermogenesis-and-systemic-glucose-homeostasis
#3
Kenji Ikeda, Qianqian Kang, Takeshi Yoneshiro, Joao Paulo Camporez, Hiroko Maki, Mayu Homma, Kosaku Shinoda, Yong Chen, Xiaodan Lu, Pema Maretich, Kazuki Tajima, Kolapo M Ajuwon, Tomoyoshi Soga, Shingo Kajimura
Uncoupling protein 1 (UCP1) plays a central role in nonshivering thermogenesis in brown fat; however, its role in beige fat remains unclear. Here we report a robust UCP1-independent thermogenic mechanism in beige fat that involves enhanced ATP-dependent Ca(2+) cycling by sarco/endoplasmic reticulum Ca(2+)-ATPase 2b (SERCA2b) and ryanodine receptor 2 (RyR2). Inhibition of SERCA2b impairs UCP1-independent beige fat thermogenesis in humans and mice as well as in pigs, a species that lacks a functional UCP1 protein...
November 13, 2017: Nature Medicine
https://www.readbyqxmd.com/read/29122978/the-structural-basis-of-ryanodine-receptor-ion-channel-function
#4
REVIEW
Gerhard Meissner
Large-conductance Ca(2+) release channels known as ryanodine receptors (RyRs) mediate the release of Ca(2+) from an intracellular membrane compartment, the endo/sarcoplasmic reticulum. There are three mammalian RyR isoforms: RyR1 is present in skeletal muscle; RyR2 is in heart muscle; and RyR3 is expressed at low levels in many tissues including brain, smooth muscle, and slow-twitch skeletal muscle. RyRs form large protein complexes comprising four 560-kD RyR subunits, four ∼12-kD FK506-binding proteins, and various accessory proteins including calmodulin, protein kinases, and protein phosphatases...
November 9, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/29071820/application-of-multigene-panel-sequencing-in-patients-with-prolonged-rate-corrected-qt-interval-and-no-pathogenic-variants-detected-in-kcnq1-kcnh2-and-scn5a
#5
Soo Hyun Seo, So Yeon Kim, Sung Im Cho, Hyunwoong Park, Seungjun Lee, Jong Moon Choi, Man Jin Kim, Jee Soo Lee, Kyung Jin Ahn, Mi Kyoung Song, Eun Jung Bae, Sung Sup Park, Moon Woo Seong
Long QT syndrome (LQTS) is an inherited cardiac disease characterized by a prolonged heart rate-corrected QT (QTc) interval. We investigated the genetic causes in patients with prolonged QTc intervals who were negative for pathogenic variants in three major LQTS-related genes (KCNQ1, KCNH2, and SCN5A). Molecular genetic testing was performed using a panel including 13 LQTS-related genes and 67 additional genes implicated in other cardiac diseases. Overall, putative genetic causes of prolonged QTc interval were identified in three of the 30 patients (10%)...
January 2018: Annals of Laboratory Medicine
https://www.readbyqxmd.com/read/29047093/cross-talk-between-mitochondrial-reactive-oxygen-species-and-sarcoplasmic-reticulum-calcium-in-pulmonary-arterial-smooth-muscle-cells
#6
Tengyao Song, Yun-Min Zheng, Yong-Xiao Wang
Hypoxic pulmonary vasoconstriction (HPV) occurs during both fetal and postnatal development and plays a critical role in matching regional alveolar perfusion with ventilation in humans and animals. HPV also contributes significantly to the development of pulmonary hypertension. Although the molecular mechanisms of HPV and pulmonary hypertension remain incompletely understood, increasing evidence demonstrates that hypoxia induces an elevated intracellular reactive oxygen species concentration ([ROS]i) in pulmonary artery smooth muscle cells (PASMCs)...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/29045723/acute-administration-of-tumour-necrosis-factor-%C3%AE-induces-spontaneous-calcium-release-via-the-reactive-oxygen-species-pathway-in-atrial-myocytes
#7
Song Zuo, Lin-Ling Li, Yan-Fei Ruan, Le Jiang, Xin Li, Song-Nan Li, Song-Nan Wen, Rong Bai, Nian Liu, Xin Du, Jian-Zeng Dong, Chang-Sheng Ma
Aims: The arrhythmogenic mechanisms of atrial fibrillation (AF) that are induced by acute inflammation, such as postoperative AF, are not well understood. We investigated the acute effects of tumour necrosis factor-α (TNF-α) that mimic acute inflammation on Ca2+ handling in isolated atrial myocytes and its underlying mechanisms. Methods and results: Cytosol Ca2+ handling and mitochondrial reactive oxygen species (ROS) production were studied in freshly isolated atrial myocytes of wild-type mice that were exposed to TNF-α (0...
October 17, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/29037982/early-effects-of-epac-depend-on-the-fine-tuning-of-the-sarcoplasmic-reticulum-ca-2-handling-in-cardiomyocytes
#8
N Lezcano, J I E Mariángelo, L Vittone, X H T Wehrens, M Said, C Mundiña-Weilenmann
In cardiac muscle, signaling through cAMP governs many fundamental cellular functions, including contractility, relaxation and automatism. cAMP cascade leads to the activation of the classic protein kinase A but also to the stimulation of the recently discovered exchange protein directly activated by cAMP (Epac). The role of Epac in the regulation of intracellular Ca(2+) homeostasis and contractility in cardiac myocytes is still matter of debate. In this study we showed that the selective Epac activator, 8-(4-chloro-phenylthio)-2'-O-methyladenosine-3', 5'-cyclic monophosphate (8-CPT), produced a positive inotropic effect when adult rat cardiac myocytes were stabilized at low [Ca(2+)]o (0...
October 14, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/29037160/-homozygous-and-compound-heterozygous-mutation-in-3-turkish-family-with-jervell-and-lange-nielsen-syndrome-case-reports
#9
Fahrettin Uysal, Burcu Turkgenc, Guven Toksoy, Ozlem M Bostan, Elif Evke, Oya Uyguner, Cengiz Yakicier, Hulya Kayserili, Ergun Cil, Sehime G Temel
BACKGROUND: Jervell and Lange-Nielsen syndrome (JLNS) isa recessive model of long QT syndrome which might also be related to possible hearing loss. Although the syndrome has been demonstrated to be originated from homozygous or compound heterozygous mutations in either the KCNQ1 or KCNE1 genes, additional mutations in other genetic loci should be considered, particularly in malignant course patients. CASE PRESENTATIONS: Three patients were admitted into hospital due to recurrent seizures/syncope, intrauterine and postnatal bradycardia respectively; moreover all three patients had congenital sensorineural hearing-loss...
October 16, 2017: BMC Medical Genetics
https://www.readbyqxmd.com/read/29032884/the-genetics-underlying-idiopathic-ventricular-fibrillation-a-special-role-for-catecholaminergic-polymorphic-ventricular-tachycardia
#10
Jaakko T Leinonen, Lia Crotti, Aurora Djupsjöbacka, Silvia Castelletti, Nella Junna, Alice Ghidoni, Annukka M Tuiskula, Carla Spazzolini, Federica Dagradi, Matti Viitasalo, Kimmo Kontula, Maria-Christina Kotta, Elisabeth Widén, Heikki Swan, Peter J Schwartz
BACKGROUND: Ventricular fibrillation (VF) is a major cause of sudden cardiac death. In some cases clinical investigations fail to identify the underlying cause and the event is classified as idiopathic (IVF). Since mutations in arrhythmia-associated genes frequently determine arrhythmia susceptibility, screening for disease-predisposing variants could improve IVF diagnostics. METHODS AND RESULTS: The study included 76 Finnish and Italian patients with a mean age of 31...
October 5, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/29032102/regulation-of-ca-2-signaling-by-acute-hypoxia-and-acidosis-in-rat-neonatal-cardiomyocytes
#11
José-Carlos Fernández-Morales, Martin Morad
Ischemic heart disease is an arrhythmogenic condition, accompanied by hypoxia, acidosis, and impaired Ca(2+) signaling. Here we report on effects of acute hypoxia and acidification in rat neonatal cardiomyocytes cultures. RESULTS: Two populations of neonatal cardiomyocyte were identified based on inactivation kinetics of L-type ICa: rapidly-inactivating ICa (τ~20ms) myocytes (prevalent in 3-4-day cultures), and slow-inactivating ICa (τ≥40ms) myocytes (dominant in 7-day cultures). Acute hypoxia (pO2<5mmHg for 50-100s) suppressed ICa reversibly in both cell-types to different extent and with different kinetics...
October 12, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/29030236/long-term-aerobic-exercise-in-calsequestrin2-knockout-mice-accentuates-vagal-antagonism-during-%C3%AE-adrenergic-stimulation-which-restricts-heart-rate-acceleration-and-paradoxically-increases-abnormal-ryanodine-receptor-calcium-leak-in-ventricular-myocytes
#12
Hsiang-Ting Ho, Senthil Thambidorai, Björn C Knollmann, George E Billman, Sandor Györke, Anuradha Kalyanasundaram
BACKGROUND: Long-term aerobic exercise alters autonomic balance, which may not be favorable in heart rate (HR)-dependent arrhythmic diseases including catecholaminergic polymorphic ventricular tachycardia (CPVT) because of preexisting bradycardia and increased sensitivity to parasympathetic stimulation. OBJECTIVE: The purpose of this study was to determine whether long-term exercise-induced autonomic adaptations modify CPVT susceptibility. METHODS: We determined exercise-induced parasympathetic effects on HR, arrhythmia incidence, and intracellular sarcoplasmic reticulum (SR) Ca(2+) leak in atrial (ACM) and ventricular (VCM) cardiomyocytes, in exercised (EX) calsequestrin knockout (CASQ2(-/-)) mice, a model of CPVT...
October 10, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/29029794/rho-kinase-inhibition-reverses-impaired-ca-2-handling-and-associated-left-ventricular-dysfunction-in-pressure-overload-induced-cardiac-hypertrophy
#13
Yusuf Olgar, Murat Cenk Celen, Bilge Eren Yamasan, Nihal Ozturk, Belma Turan, Semir Ozdemir
Recent studies have implicated a relationship between RhoA/ROCK activity and defective Ca(2+) homeostasis in hypertrophic hearts. This study investigated molecular mechanism underlying ROCK inhibition-mediated cardioprotection against pressure overload-induced cardiac hypertrophy, with a focus on Ca(2+) homeostasis. Cardiac hypertrophy model was established by performing transverse aortic constriction (TAC) in 8-week-old male rats. Groups were assigned as SHAM, TAC and TAC+Fas (rats undergoing TAC and treated with fasudil)...
November 2017: Cell Calcium
https://www.readbyqxmd.com/read/29027245/epac-induced-ryanodine-receptor-type-2-activation-inhibits-sodium-currents-in-atrial-and-ventricular-murine-cardiomyocytes
#14
Haseeb Valli, Shiraz Ahmad, Sujan Sriharan, Lydia D Dean, Andrew A Grace, Kamalan Jeevaratnam, Hugh R Matthews, Christopher L-H Huang
Acute RyR2 activation by exchange protein directly activated by cAMP (Epac) reversibly perturbs myocyte Ca(2+) homeostasis, slows myocardial action potential conduction, and exerts pro-arrhythmic effects. Loose patch-clamp studies, preserving in vivo extracellular and intracellular conditions, investigated Na(+) current in intact cardiomyocytes in murine atrial and ventricular preparations following Epac activation. Depolarising steps to varying test voltages activated typical voltage-dependent Na(+) currents...
October 12, 2017: Clinical and Experimental Pharmacology & Physiology
https://www.readbyqxmd.com/read/28988521/the-cardioprotective-effect-of-rosmarinic-acid-on-acute-myocardial-infarction-and-genes-involved-in-ca-2-homeostasis
#15
Somayeh Javidanpour, Mahin Dianat, Mohammad Badavi, Seyyed Ali Mard
Acute myocardial infarction (AMI) is a common cause of hospitalisation and high mortality due to lethal arrhythmias. Sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) and ryanodine receptor (RyR2) regulate the cytosolic Ca(2+) ion concentration. Rosmarinic acid (RA) is one of the most common caffeic esters in Rosmarinus officinalis. The present study was conducted to test the hypothesis whether RA can protect cardiac function against AMI and arrhythmias induced by isoproterenol through the regulatory effect of SERCA2 and RyR2 gene expression...
November 3, 2017: Free Radical Research
https://www.readbyqxmd.com/read/28974554/thyroid-and-glucocorticoid-hormones-promote-functional-t-tubule-development-in-human-induced-pluripotent-stem-cell-derived-cardiomyocytes
#16
Shan S Parikh, Daniel J Blackwell, Nieves Gomez-Hurtado, Michael Frisk, Lili Wang, Kyungsoo Kim, Christen P Dahl, Arnt E Fiane, Theis Tønnessen, Dmytro O Kryshtal, William E Louch, Bjorn C Knollmann
Rationale: Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM) are increasingly being used for modeling heart disease and are under development for regeneration of the injured heart. However, incomplete structural and functional maturation of hiPSC-CM including lack of t-tubules, immature excitation-contraction (EC) coupling, and inefficient Ca-induced Ca release (CICR) remain major limitations. Objective: Thyroid and glucocorticoid hormones are critical for heart maturation. We hypothesized that their addition to standard protocols would promote t-tubule development and mature EC coupling of hiPSC-CM when cultured on extracellular matrix with physiological stiffness (Matrigel mattress)...
October 2, 2017: Circulation Research
https://www.readbyqxmd.com/read/28974495/prenatal-hypoxia-induced-dysfunction-in-cerebral-arteries-of-offspring-rats
#17
Jiaqi Tang, Na Li, Xueyi Chen, Qinqin Gao, Xiuwen Zhou, Yingying Zhang, Bailin Liu, Miao Sun, Zhice Xu
BACKGROUND: Hypoxia during pregnancy could cause abnormal development and lead to increased risks of vascular diseases in adults. This study determined angiotensin II (AII)-mediated vascular dysfunction in offspring middle cerebral arteries (MCA). METHODS AND RESULTS: Pregnant rats were subjected to hypoxia. Vascular tension in offspring MCA by AII with or without inhibitors, calcium channel activities, and endoplasmic reticulum calcium stores were tested. Whole-cell patch clamping was used to investigate voltage-dependent calcium channel currents...
October 3, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28964152/minimal-model-for-calcium-alternans-due-to-sr-release-refractoriness
#18
Inma R Cantalapiedra, Enrique Alvarez-Lacalle, Angelina Peñaranda, Blas Echebarria
In the heart, rapid pacing rates may induce alternations in the strength of cardiac contraction, termed pulsus alternans. Often, this is due to an instability in the dynamics of the intracellular calcium concentration, whose transients become larger and smaller at consecutive beats. This alternation has been linked experimentally and theoretically to two different mechanisms: an instability due to (1) a strong dependence of calcium release on sarcoplasmic reticulum (SR) load, together with a slow calcium reuptake into the SR or (2) to SR release refractoriness, due to a slow recovery of the ryanodine receptors (RyR2) from inactivation...
September 2017: Chaos
https://www.readbyqxmd.com/read/28964110/a-model-of-cardiac-ryanodine-receptor-gating-predicts-experimental-ca-2-dynamics-and-ca-2-triggered-arrhythmia-in-the-long-qt-syndrome
#19
Dan Wilson, Bard Ermentrout, Jan Němec, Guy Salama
Abnormal Ca(2+) handling is well-established as the trigger of cardiac arrhythmia in catecholaminergic polymorphic ventricular tachycardia and digoxin toxicity, but its role remains controversial in Torsade de Pointes (TdP), the arrhythmia associated with the long QT syndrome (LQTS). Recent experimental results show that early afterdepolarizations (EADs) that initiate TdP are caused by spontaneous (non-voltage-triggered) Ca(2+) release from Ca(2+)-overloaded sarcoplasmic reticulum (SR) rather than the activation of the L-type Ca(2+)-channel window current...
September 2017: Chaos
https://www.readbyqxmd.com/read/28961276/cpvt-associated-cardiac-ryanodine-receptor-mutation-g357s-with-reduced-penetrance-impairs-ca2-release-termination-and-diminishes-protein-expression
#20
Yingjie Liu, Jinhong Wei, Siobhan M Wong King Yuen, Bo Sun, Yijun Tang, Ruiwu Wang, Filip Van Petegem, S R Wayne Chen
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is one of the most lethal inherited cardiac arrhythmias mostly linked to cardiac ryanodine receptor (RyR2) mutations with high disease penetrance. Interestingly, a novel RyR2 mutation G357S discovered in a large family of more than 1400 individuals has reduced penetrance. The molecular basis for the incomplete disease penetrance in this family is unknown. To gain insights into the variable disease expression in this family, we determined the impact of the G357S mutation on RyR2 function and expression...
2017: PloS One
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