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https://www.readbyqxmd.com/read/28435065/influence-of-er-leak-on-resting-cytoplasmic-ca-2-and-receptor-mediated-ca-2-signalling-in-human-macrophage
#1
Janice A Layhadi, Samuel J Fountain
Mechanisms controlling endoplasmic reticulum (ER) Ca(2+) homeostasis are important regulators of resting cytoplasmic Ca(2+) concentration ([Ca(2+)]cyto) and receptor-mediated Ca(2+) signalling. Here we investigate channels responsible for ER Ca(2+) leak in THP-1 macrophage and human primary macrophage. In the absence of extracellular Ca(2+) we employ ionomycin action at the plasma membrane to stimulate ER Ca(2+) leak. Under these conditions ionomycin elevates [Ca(2+)]cyto revealing a Ca(2+) leak response which is abolished by thapsigargin...
April 20, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28428008/force-development-and-intracellular-ca-2-in-intact-cardiac-muscles-from-gravin-mutant-mice
#2
Zhitao Li, Sonal Singh, Santosh V Suryavanshi, Wengang Ding, Xiaoxu Shen, Cori S Wijaya, Wei Dong Gao, Bradley K McConnell
Gravin (AKAP12) is an A-kinase-anchoring-protein that scaffolds protein kinase A (PKA), β2-adrenergic receptor (β2-AR), protein phosphatase 2B and protein kinase C. Gravin facilitates β2-AR-dependent signal transduction through PKA to modulate cardiac excitation-contraction coupling and its removal positively affects cardiac contraction. Trabeculae from the right ventricles of gravin mutant (gravin-t/t) mice were employed for force determination. Simultaneously, corresponding intracellular Ca(2+) transient ([Ca(2+)]i) were measured...
April 17, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28413806/ryanodine-and-ip3-receptor-mediated-calcium-signaling-play-a-pivotal-role-in-neurological-infrared-laser-modulation
#3
Gleb P Tolstykh, Cory A Olsovsky, Bennett L Ibey, Hope T Beier
Pulsed infrared (IR) laser energy has been shown to modulate neurological activity through both stimulation and inhibition of action potentials. While the mechanism(s) behind this phenomenon is (are) not completely understood, certain hypotheses suggest that the rise in temperature from IR exposure could activate temperature- or pressure-sensitive ion channels or create pores in the cellular outer membrane, allowing an influx of typically plasma-membrane-impermeant ions. Studies using fluorescent intensity-based calcium ion ([Formula: see text]) sensitive dyes show changes in [Formula: see text] levels after various IR stimulation parameters, which suggests that [Formula: see text] may originate from the external solution...
April 2017: Neurophotonics
https://www.readbyqxmd.com/read/28403410/assessing-the-pathogenicity-of-ryr1-variants-in-malignant-hyperthermia
#4
A Merritt, P Booms, M-A Shaw, D M Miller, C Daly, J G Bilmen, K M Stowell, P D Allen, D S Steele, P M Hopkins
Background: . Missense variants in the ryanodine receptor 1 gene ( RYR1 ) are associated with malignant hyperthermia but only a minority of these have met the criteria for use in predictive DNA diagnosis. We examined the utility of a simplified method of segregation analysis and a functional assay for determining the pathogenicity of recurrent RYR1 variants associated with malignant hyperthermia. Methods: . We identified previously uncharacterised RYR1 variants found in four or more malignant hyperthermia families and conducted simplified segregation analyses...
April 1, 2017: British Journal of Anaesthesia
https://www.readbyqxmd.com/read/28402838/exposure-of-honey-bees-apis-mellifera-to-different-classes-of-insecticides-exhibit-distinct-molecular-effect-patterns-at-concentrations-that-mimic-environmental-contamination
#5
Verena Christen, Karl Fent
Pesticides are implicated in the decline of honey bee populations. Many insecticides are neurotoxic and act by different modes of actions. Although a link between insecticide exposure and changed behaviour has been made, molecular effects underlying these effects are poorly understood. Here we elucidated molecular effects at environmental realistic concentrations of two organophosphates, chlorpyrifos and malathion, the pyrethroid cypermethrin, and the ryanodine receptor activator, chlorantraniliprole. We assessed transcriptional alterations of selected genes at three exposure times (24 h, 48 h, 72 h) in caged honey bees exposed to different concentrations of these compounds...
April 9, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28400318/hemopexin-counteracts-systolic-dysfunction-induced-by-heme-driven-oxidative-stress
#6
Giada Ingoglia, Can Martin Sag, Nikolai Rex, Lucia De Franceschi, Francesca Vinchi, James Cimino, Sara Petrillo, Stefan Wagner, Klaus Kreitmeier, Lorenzo Silengo, Fiorella Altruda, Lars S Maier, Emilio Hirsch, Alessandra Ghigo, Emanuela Tolosano
Heart failure is a leading cause of morbidity and mortality in patients affected by different disorders associated to intravascular hemolysis. The leading factor is the presence of pathologic amount of pro-oxidant free heme in the bloodstream, due to the exhaustion of the natural heme scavenger Hemopexin (Hx). Here, we evaluated whether free heme directly affects cardiac function, and tested the therapeutic potential of replenishing serum Hx for increasing serum heme buffering capacity. The effect of heme on cardiac function was assessed in vitro, on primary cardiomyocytes and H9c2 myoblast cell line, and in vivo, in Hx(-/-) mice and in genetic and acquired mouse models of intravascular hemolysis...
April 8, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28390800/ca-2-release-via-two-pore-channel-type-2-tpc2-is-required-for-slow-muscle-cell-myofibrillogenesis-and-myotomal-patterning-in-intact-zebrafish-embryos
#7
Jeffrey J Kelu, Sarah E Webb, John Parrington, Antony Galione, Andrew L Miller
We recently demonstrated a critical role for two-pore channel type 2 (TPC2)-mediated Ca(2+) release during the differentiation of slow (skeletal) muscle cells (SMC) in intact zebrafish embryos, via the introduction of a translational-blocking morpholino antisense oligonucleotide (MO). Here, we extend our study and demonstrate that knockdown of TPC2 with a non-overlapping splice-blocking MO, knockout of TPC2 (via the generation of a tpcn2(dhkz1a) mutant line of zebrafish using CRISPR/Cas9 gene-editing), or the pharmacological inhibition of TPC2 action with bafilomycin A1 or trans-ned-19, also lead to a significant attenuation of SMC differentiation, characterized by a disruption of SMC myofibrillogenesis and gross morphological changes in the trunk musculature...
April 6, 2017: Developmental Biology
https://www.readbyqxmd.com/read/28387457/dampened-activity-of-ryanodine-receptor-channels-in-mutant-skeletal-muscle-lacking-tric-a
#8
Sam El-Ajouz, Elisa Venturi, Katja Witschas, Matthew Beech, Abigail D Wilson, Chris Lindsay, David Eberhardt, Fiona O'Brien, Tsunaki Iida, Miyuki Nishi, Hiroshi Takeshima, Rebecca Sitsapesan
TRIC-A is a major component of the nuclear and sarcoplasmic reticulum (SR) membranes of cardiac and skeletal muscle, and is localised closely with RyR channels in the SR terminal cisternae. The skeletal muscle of Tric-a KO mice is characterised by Ca(2+) overloaded and swollen SR and by changes in the properties of SR Ca(2+) release. We therefore investigated if RyR1 gating behaviour is modified in the SR from Tric-a KO mice by incorporating native RyR1 into planar phospholipid bilayers under voltage-clamp conditions...
April 7, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28384221/kchip2-regulates-the-cardiac-ca2-transient-and-myocyte-contractility-by-targeting-ryanodine-receptor-activity
#9
Drew M Nassal, Xiaoping Wan, Haiyan Liu, Kenneth R Laurita, Isabelle Deschênes
Pathologic electrical remodeling and attenuated cardiac contractility are featured characteristics of heart failure. Coinciding with these remodeling events is a loss of the K+ channel interacting protein, KChIP2. While, KChIP2 enhances the expression and stability of the Kv4 family of potassium channels, leading to a more pronounced transient outward K+ current, Ito,f, the guinea pig myocardium is unique in that Kv4 expression is absent, while KChIP2 expression is preserved, suggesting alternative consequences to KChIP2 loss...
2017: PloS One
https://www.readbyqxmd.com/read/28373957/comparative-study-the-expression-of-calcium-cycling-genes-in-bombay-duck-harpadon-nehereus-and-beltfish-trichiurus-lepturus-with-different-swimming-activities
#10
Hui Zhang, Gilbert Audira, Yuan Li, Weiwei Xian, Muhammed Muhsin Varikkodan, Chung-Der Hsiao
The contraction and relaxation events of the muscle is mediated by the coordination of many important calcium cycling proteins of ryanodine receptor (RYR), troponin C (TNNC), parvalbumin (PVALB), sarcoendoplasmic reticulum calcium transport ATPase (SERCA) and calsequestrin (CASQ). In higher vertebrates, the expression level of calcium cycling proteins are positively correlated to the muscle contraction/relaxation ability of the cell. In this study, we used RNAseq to explore the expression profile of calcium cycling genes between two marine fish of Bombay duck (Harpadon nehereus) and beltfish (Trichiurus lepturus) with poor and robust swimming activities, respectively...
June 2017: Genomics Data
https://www.readbyqxmd.com/read/28373535/dantrolene-requires-mg-2-to-arrest-malignant-hyperthermia
#11
Rocky H Choi, Xaver Koenig, Bradley S Launikonis
Malignant hyperthermia (MH) is a clinical syndrome of skeletal muscle that presents as a hypermetabolic response to volatile anesthetic gases, where susceptible persons may develop lethally high body temperatures. Genetic predisposition mainly arises from mutations on the skeletal muscle ryanodine receptor (RyR). Dantrolene is administered to alleviate MH symptoms, but its mechanism of action and its influence on the Ca(2+) transients elicited by MH triggers are unknown. Here, we show that Ca(2+) release in the absence of Mg(2+) is unaffected by the presence of dantrolene but that dantrolene becomes increasingly effective as cytoplasmic-free [Mg(2+)] (free [Mg(2+)]cyto) passes mM levels...
April 3, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28370211/a-protocol-for-registration-and-correction-of-multicolour-sted-superresolution-images
#12
E Hebisch, E Wagner, V Westphal, J J Sieber, S E Lehnart
Multicolour fluorescence imaging by STimulated Emission Depletion (STED) superresolution microscopy with doughnut-shaped STED laser beams based on different wavelengths for each colour channel requires precise image registration. This is especially important when STED imaging is used for co-localisation studies of two or more native proteins in biological specimens to analyse nanometric subcellular spatial arrangements. We developed a robust postprocessing image registration protocol, with the aim to verify and ultimately optimise multicolour STED image quality...
April 3, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28369767/multiple-targets-for-flecainide-action-implications-for-cardiac-arrhythmogenesis
#13
REVIEW
Samantha C Salvage, Karthik H Chandrasekharan, Kamalan Jeevaratnam, Angela F Dulhunty, Andrew J Thompson, Antony P Jackson, Christopher L-H Huang
Flecainide suppresses cardiac tachyarrhythmias including paroxysmal atrial fibrillation, supraventricular tachycardia, arrhythmic long QT syndromes (LQTS), as well as the Ca(2+) -mediated, catecholaminergic polymorphic ventricular, tachycardia (CPVT). However, flecainide can also exert pro-arrhythmic effects most notably following myocardial infarction and when used to diagnose Brugada Syndrome (BrS). These divergent actions result from its physiological and pharmacological actions at multiple, interacting, levels of cellular organisation...
April 3, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28356340/analysis-of-cardiac-myocyte-maturation-using-casaav-a-platform-for-rapid-dissection-of-cardiac-myocyte-gene-function-in-vivo
#14
Yuxuan Guo, Nathan J VanDusen, Lina Zhang, Weiliang Gu, Isha Sethi, Silvia Guatimosim, Qing Ma, Blake D Jardin, Yulan Ai, Donghui Zhang, Biyi Chen, Ang Guo, Guo-Cheng Yuan, Long-Sheng Song, William T Pu
Rationale: Loss-of-function studies in cardiac myocytes (CMs) are currently limited by the need for appropriate conditional knockout alleles. The factors that regulate CM maturation are poorly understood. Prior studies on CM maturation have been confounded by heart dysfunction caused by whole organ gene inactivation. Objective: To develop a new technical platform to rapidly characterize cell-autonomous gene function in postnatal murine CMs and apply it to identify genes that regulate T-tubules, a hallmark of mature cardiac myocytes...
March 29, 2017: Circulation Research
https://www.readbyqxmd.com/read/28352365/heart-failure-modulates-electropharmacological-characteristics-of-sinoatrial-nodes
#15
Shih-Lin Chang, Hui-Lun Chuang, Yao-Chang Chen, Yu-Hsun Kao, Yung-Kuo Lin, Yung-Hsin Yeh, Shih-Ann Chen, Yi-Jen Chen
The impact of heart failure (HF) on sinoatrial node (SAN) channel regulation and electropharmacological responses has remained elusive. The present study aimed to investigate the effects of HF on the electrical activity of SANs with and without pharmacological interventions. Action potentials (APs) were recorded in isolated SANs from normal rabbits (control) and those with HF (rapid ventricular pacing for 4 weeks) prior to and after administration of a funny current blocker (ivabradine; 0.1, 0.3, 3 or 10 µM), a calmodulin kinase II inhibitor (KN-93; 0...
February 2017: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28351836/structural-and-biophysical-analyses-of-the-skeletal-dihydropyridine-receptor-beta-subunit-%C3%AE-1a-reveal-critical-roles-of-domain-interactions-for-stability
#16
Nicole C Norris, Soumya Joseph, Shouvik Aditya, Yamuna Karunasekara, Philip G Board, Angela F Dulhunty, Aaron J Oakley, Marco G Casarotto
Excitation-contraction (EC) coupling in skeletal muscle requires a physical interaction between the voltage-gated calcium channel dihydropyridine receptor (DHPR) and the ryanodine receptor (RyR1) Ca2+ release channel. Although the exact molecular mechanism that initiates skeletal EC coupling is unresolved, it is clear that both the α1s and β subunits of DHPR are essential for this process. Here, we employed a series of techniques, including size-exclusion chromatography-multi-angle light scattering, differential scanning fluorimetry and isothermal calorimetry, to characterize various biophysical properties of the skeletal DHPR beta subunit β1a...
March 28, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28339694/regional-acidosis-locally-inhibits-but-remotely-stimulates-ca2-waves-in-ventricular-myocytes
#17
Kerrie L Ford, Emma L Moorhouse, Mario Bortolozzi, Mark Richards, Pawel Swietach, Richard D Vaughan-Jones
AIMS: Spontaneous Ca2+ waves in cardiomyocytes are potentially arrhythmogenic. A powerful controller of Ca2+ waves is the cytoplasmic H+ concentration ([H+]i), which fluctuates spatially and temporally in conditions such as myocardial ischaemia/reperfusion. H+-control of Ca2+ waves is poorly understood. We have therefore investigated how [H+]i co-ordinates their initiation and frequency. METHODS AND RESULTS: Spontaneous Ca2+ waves were imaged (fluo-3) in rat isolated ventricular myocytes, subjected to modest Ca2+-overload...
February 21, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28337975/a-chemical-chaperone-improves-muscle-function-in-mice-with-a-ryr1-mutation
#18
Chang Seok Lee, Amy D Hanna, Hui Wang, Adan Dagnino-Acosta, Aditya D Joshi, Mark Knoblauch, Yan Xia, Dimitra K Georgiou, Jianjun Xu, Cheng Long, Hisayuki Amano, Corey Reynolds, Keke Dong, John C Martin, William R Lagor, George G Rodney, Ergun Sahin, Caroline Sewry, Susan L Hamilton
Mutations in the RYR1 gene cause severe myopathies. Mice with an I4895T mutation in the type 1 ryanodine receptor/Ca(2+) release channel (RyR1) display muscle weakness and atrophy, but the underlying mechanisms are unclear. Here we show that the I4895T mutation in RyR1 decreases the amplitude of the sarcoplasmic reticulum (SR) Ca(2+) transient, resting cytosolic Ca(2+) levels, muscle triadin content and calsequestrin (CSQ) localization to the junctional SR, and increases endoplasmic reticulum (ER) stress/unfolded protein response (UPR) and mitochondrial ROS production...
March 24, 2017: Nature Communications
https://www.readbyqxmd.com/read/28333380/smooth-muscle-ion-channels-and-regulation-of-vascular-tone-in-resistance-arteries-and-arterioles
#19
Nathan R Tykocki, Erika M Boerman, William F Jackson
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs...
March 16, 2017: Comprehensive Physiology
https://www.readbyqxmd.com/read/28332202/calcium-signalling-silencing-in-atrial-fibrillation
#20
Maura Greiser
Sub-cellular calcium signalling silencing is a novel and distinct cellular and molecular adaptive response to rapid cardiac activation. Calcium signalling silencing develops during short-term sustained rapid atrial activation as seen clinically during paroxysmal atrial fibrillation (AF). It is the first 'anti-arrhythmic' adaptive response in the setting of AF and appears to counteract the maladaptive changes that lead to intracellular Ca(2+) signalling instability and Ca(2+) based arrhythmogenicity. Calcium signalling silencing results in a failed propagation of the [Ca(2+) ]i signal to the myocyte centre in both patients with AF and in a rabbit model...
March 22, 2017: Journal of Physiology
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