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Sarcoplasmic reticulum

Jian Shi, Francesc Miralles, Lutz Birnbaumer, William A Large, Anthony P Albert
In vascular smooth muscle cells (VSMCs), stimulation of TRPC1-based SOCs mediate Ca(2+) entry pathways which regulate contractility, proliferation and migration. It is therefore important to understand how these channels are activated. Studies have shown that stimulation of TRPC1-based SOCs requires Gαq/PLCβ1 activities and PKC phosphorylation, but it is unclear how store depletion stimulates this gating pathway. The present work examines this issue by focusing on the role of STIM1, an endo/sarcoplasmic reticulum Ca(2+) sensor...
October 18, 2016: Journal of Physiology
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
Yong Xie, Zhen-Jie Gu, Mao-Xiong Wu, Tu-Cheng Huang, Jing-Song Ou, Huiping-Son Ni, Mao-Huan Lin, Wo-Liang Yuan, Jing-Feng Wang, Yang-Xin Chen
AIMS: Adverse cardiovascular effects induced by peroxisome proliferator activator receptor-γ (PPAR-γ) activation were observed in clinical setting. But the underlying mechanism is unclear. Now, transgenic mice with cardiac specific peroxisome proliferator activator receptor-γ overexpression (TG-PPAR-γ) were used to explore the possible mechanisms. MATERIALS AND METHODS: Cardiac tissues from TG-PPAR-γ mice, a PPAR-γ over-expressing human cardiomyocyte line AC16 cell, and PPAR-γ agonist-treated primary cardiomyocytes were used to evaluate the expression of cardiac calcium regulatory proteins as sarcoplasmic reticulum Ca(2+) ATPase, Na(+)/Ca(2+)exchanger 1, ryanodine receptor 2 and phospholamban...
October 13, 2016: Life Sciences
Fábio V G Campanha, Denise Perone, Dijon H S de Campos, Renata de A M Luvizotto, Maria T De Síbio, Miriane de Oliveira, Regiane M C Olimpio, Fernanda C F Moretto, Carlos R Padovani, Gláucia M F S Mazeto, Antonio C Cicogna, Célia R Nogueira
Objective: The current study was aimed at analyzing sarcoplasmic reticulum Ca2+ ATPase (Serca2) and ryanodine receptor type 2 (Ryr2) gene expression in rats subjected to surgery that induced HF and were subsequently treated with T4 using physiological doses. Materials and methods: HF was induced in 18 male Wistar rats by clipping the ascending thoracic aorta to generate aortic stenosis (HFS group), while the control group (9-sham) underwent thoracotomy. After 21 weeks, the HFS group was subdivided into two subgroups...
October 10, 2016: Archives of Endocrinology and Metabolism
Joseph Michael Autry, David D Thomas, L Michel Espinoza-Fonseca
We have performed μs molecular dynamics simulation (MDS) to identify structural mechanisms for sarcolipin (SLN) uncoupling of Ca(2+) transport from ATP hydrolysis for the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA). SLN regulates muscle metabolism and energy expenditure to provide resistance against diet-induced obesity and extreme cold. MDS demonstrates that the cytosolic domain of SLN induces a salt bridge-mediated structural rearrangement in the energy-transduction domain of SERCA. We propose that this structural change uncouples SERCA by perturbing Ca(2+) occlusion at residue E309 in transport site II, thus facilitating cytosolic Ca(2+) backflux...
October 12, 2016: Biochemistry
Sophie Le Page, Marjorie Niro, Jérémy Fauconnier, Laura Cellier, Sophie Tamareille, Abdallah Gharib, Arnaud Chevrollier, Laurent Loufrani, Céline Grenier, Rima Kamel, Emmanuelle Sarzi, Alain Lacampagne, Michel Ovize, Daniel Henrion, Pascal Reynier, Guy Lenaers, Delphine Mirebeau-Prunier, Fabrice Prunier
BACKGROUND: Recent data suggests the involvement of mitochondrial dynamics in cardiac ischemia/reperfusion (I/R) injuries. Whilst excessive mitochondrial fission has been described as detrimental, the role of fusion proteins in this context remains uncertain. OBJECTIVES: To investigate whether Opa1 (protein involved in mitochondrial inner-membrane fusion) deficiency affects I/R injuries. METHODS AND RESULTS: We examined mice exhibiting Opa1delTTAG mutations (Opa1+/-), showing 70% Opa1 protein expression in the myocardium as compared to their wild-type (WT) littermates...
2016: PloS One
Martin Laasmaa, Rikke Birkedal, Marko Vendelin
In cardiac excitation-contraction coupling (ECC), calcium enters the cytosol via L-type Ca(2+) channels (LTCC) and reverse Na(+)/Ca(2+)-exchange (NCXrev), or is released from the sarcoplasmic reticulum (SR) by Ca(2+)-induced Ca(2+)-release (CICR). The magnitude of Ca(2+) influx via the different pathways varies with the state of the cell and is difficult to assess quantitatively, because changes in Ca(2+) influx through one pathway affects the others. In rainbow trout ventricular myocytes, the role of the SR has been uncertain for decades...
October 1, 2016: Journal of Molecular and Cellular Cardiology
Hanting Yang, Miaohui Hu, Jianli Guo, Xiaomin Ou, Tanxi Cai, Zhenfeng Liu
Intracellular Ca(2+) signalling processes are fundamental to muscle contraction, neurotransmitter release, cell growth and apoptosis. Release of Ca(2+) from the intracellular stores is supported by a series of ion channels in sarcoplasmic or endoplasmic reticulum (SR/ER). Among them, two isoforms of the trimeric intracellular cation (TRIC) channel family, named TRIC-A and TRIC-B, modulate the release of Ca(2+) through the ryanodine receptor or inositol triphosphate receptor, and maintain the homeostasis of ions within SR/ER lumen...
October 3, 2016: Nature
A F Dulhunty, L Wei-LaPierre, M G Casarotto, N A Beard
The core skeletal muscle ryanodine receptor (RyR1) calcium release complex extends through three compartments of the muscle fibre, linking the extracellular environment through the cytoplasmic junctional gap to the lumen of the internal sarcoplasmic reticulum (SR) calcium store. The protein complex is essential for skeletal excitation-contraction (EC-) coupling and skeletal muscle function. Its importance is highlighted by perinatal death if any one of the EC-coupling components are missing and by myopathies associated with mutation of any of the proteins...
October 1, 2016: Clinical and Experimental Pharmacology & Physiology
Felix Hohendanner, Jaime DeSantiago, Frank R Heinzel, Lothar A Blatter
We tested the hypothesis that in atrial myocytes from a rabbit left ventricular heart failure (HF) model, spatial inhomogeneity and temporal dyssynchrony of Ca removal during excitation-contraction coupling together with increased Na/Ca exchange (NCX) activity generates a substrate for proarrhythmic Ca release. Ca removal occurs via Ca reuptake into the sarcoplasmic reticulum and extrusion via NCX exclusively in the cell periphery since rabbit atrial myocytes lack transverse tubules. Ca removal kinetics were assessed by the time constant τ of decay of local peripheral subsarcolemmal (SS) and central (CT) action potential (AP) induced Ca transients (CaTs) recorded in confocal line scan mode (using Fluo-4)...
September 30, 2016: American Journal of Physiology. Heart and Circulatory Physiology
Oliver B Clarke, Wayne A Hendrickson
Ryanodine receptors (RyRs) are intracellular cation channels that mediate the rapid and voluminous release of Ca(2+) from the sarcoplasmic reticulum (SR) as required for excitation-contraction coupling in cardiac and skeletal muscle. Understanding of the architecture and gating of RyRs has advanced dramatically over the past two years, due to the publication of high resolution cryo-electron microscopy (cryoEM) reconstructions and associated atomic models of multiple functional states of the skeletal muscle receptor, RyR1...
August 2016: Current Opinion in Structural Biology
Julie Larsen, Peter Bushnell, John Steffensen, Morten Pedersen, Klaus Qvortrup, Richard Brill
We assessed the functional properties in atrial and ventricular myocardium (using isolated cardiac strips) of smooth dogfish (Mustelus canis), clearnose skate (Raja eglanteria), and sandbar shark (Carcharhinus plumbeus) by blocking Ca(2+) release from the sarcoplasmic reticulum (SR) with ryanodine and thapsigargin and measuring the resultant changes in contraction-relaxation parameters and the force-frequency relationship at 20 °C and 30 °C. We also examined ultrastructural differences with electron microscopy...
September 29, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Kevin M Lewis, Gerhard R Munske, Samuel S Byrd, Jeehoon Kang, Hyun-Jai Cho, Eduardo Ríos, ChulHee Kang
Calsequestrin is glycosylated and phosphorylated during its transit to its final destination in the junctional sarcoplasmic reticulum. To determine the significance and universal profile of these post-translational modifications to mammalian calsequestrin, we characterized, via mass spectrometry, the glycosylation and phosphorylation of skeletal muscle calsequestrin from cattle (B. taurus), lab mice (M. musculus) and lab rats (R. norvegicus) and cardiac muscle calsequestrin from cattle, lab rats and humans...
2016: International Journal of Molecular Sciences
Marisa Sepúlveda, Luis A Gonano, Manuel Viotti, Malena Morell, Paula Blanco, Micaela López Alarcón, Isalira Peroba Ramos, Adriana Bastos Carvalho, Emiliano Medei, Martín Vila Petroff
OBJECTIVES: Sepsis is associated with cardiac contractile dysfunction attributed to alterations in Ca handling. We examined the subcellular mechanisms involved in sarcoplasmic reticulum Ca loss that mediate altered Ca handling and contractile dysfunction associated with sepsis. DESIGN: Randomized controlled trial. SETTING: Research laboratory SUBJECTS:: Male wild type and transgenic mice INTERVENTIONS:: We induced sepsis in mice using the colon ascendens stent peritonitis model...
September 19, 2016: Critical Care Medicine
Hsiang-Ting Ho, Andriy E Belevych, Bin Liu, Ingrid M Bonilla, Przemysław B Radwański, Igor V Kubasov, Héctor H Valdivia, Karsten Schober, Cynthia A Carnes, Sándor Györke
Although the effects and the underlying mechanism of sympathetic stimulation on cardiac Ca handling are relatively well established both in health and disease, the modes of action and mechanisms of parasympathetic modulation are poorly defined. Here, we demonstrate that parasympathetic stimulation initiates a novel mode of excitation-contraction coupling that enhances the efficiency of cardiac sarcoplasmic reticulum Ca store utilization. This efficient mode of excitation-contraction coupling involves reciprocal changes in the phosphorylation of ryanodine receptor 2 at Ser-2808 and Ser-2814...
November 2016: Hypertension
Limin Sun, Man Bai, Lujie Xiang, Guishan Zhang, Wei Ma, Huaizhi Jiang
The Qianhua Mutton Merino (QHMM) is a new sheep (Ovis aries) variety with better meat performance compared with the traditional local variety Small Tail Han (STH) sheep. We aimed to evaluate the transcriptome regulators associated with muscle growth and development between the QHMM and STH. We used RNA-Seq to obtain the transcriptome profiles of the longissimus muscle from the QHMM and STH. The results showed that 960 genes were differentially expressed (405 were up-regulated and 555 were down-regulated). Among these, 463 differently expressed genes (DEGs) were probably associated with muscle growth and development and were involved in biological processes such as skeletal muscle tissue development and muscle cell differentiation; molecular functions such as catalytic activity and oxidoreductase activity; cellular components such as mitochondrion and sarcoplasmic reticulum; and pathways such as metabolic pathways and citrate cycle...
2016: Scientific Reports
Sören Brandenburg, Tobias Kohl, George S B Williams, Konstantin Gusev, Eva Wagner, Eva A Rog-Zielinska, Elke Hebisch, Miroslav Dura, Michael Didié, Michael Gotthardt, Viacheslav O Nikolaev, Gerd Hasenfuss, Peter Kohl, Christopher W Ward, W Jonathan Lederer, Stephan E Lehnart
The canonical atrial myocyte (AM) is characterized by sparse transverse tubule (TT) invaginations and slow intracellular Ca2+ propagation but exhibits rapid contractile activation that is susceptible to loss of function during hypertrophic remodeling. Here, we have identified a membrane structure and Ca2+-signaling complex that may enhance the speed of atrial contraction independently of phospholamban regulation. This axial couplon was observed in human and mouse atria and is composed of voluminous axial tubules (ATs) with extensive junctions to the sarcoplasmic reticulum (SR) that include ryanodine receptor 2 (RyR2) clusters...
October 3, 2016: Journal of Clinical Investigation
Adonis Z Wu, Dongzhu Xu, Na Yang, Shien-Fong Lin, Peng-Sheng Chen, Steven E Cala, Zhenhui Chen
AIMS: Phospholamban (PLB) regulates the cardiac Ca(2+)-ATPase (SERCA2a) in sarcoplasmic reticulum (SR). However, the localization of PLB at subcellular sites outside the SR and possible contributions to Ca(2+) cycling remain unknown. We examined the intracellular distribution of PLB and tested whether a pool of PLB exists in the nuclear envelope (NE) that might regulate perinuclear/nuclear Ca(2+) (nCa(2+)) handling in cardiomyocytes (CMs). METHODS AND RESULTS: Using confocal immunofluorescence microscopy and immunoblot analyses of CMs and CM nuclei, we discovered that PLB was highly concentrated in NE...
September 15, 2016: Journal of Molecular and Cellular Cardiology
Tamás Oláh, Dóra Bodnár, Adrienn Tóth, János Vincze, János Fodor, Barbara Reischl, Adrienn Kovács, Olga Ruzsnavszky, Beatrix Dienes, Péter Szentesi, Oliver Friedrich, László Csernoch
Marijuana was found to cause muscle weakness, but it is unknown whether it affects the muscles directly, or modulates only the motor control of the central nervous system. Although the presence of CB1 cannabinoid receptors (CB1R) - responsible for the psychoactive effects of the drug in the brain - have recently been shown in skeletal muscle, it is unclear how CB1R-mediated signalling affects the contraction and Ca²⁺ homeostasis of mammalian skeletal muscle. Here we demonstrate that in vitro CB1R activation increased muscle fatigability, decreased the Ca(2+) -sensitivity of the contractile apparatus, but did not alter the amplitude of single twitch contractions...
September 19, 2016: Journal of Physiology
Yufen Li, Xiaomei Wang, Changli Lou
BACKGROUND Calcium overload, inflammation, and apoptosis play important roles in myocardial ischemia-reperfusion injury (MIRI). Gastrodin pretreatment can alleviate MIRI. This study observed sarcoplasmic reticulum calcium transport ATPase (Ca2+-ATPase, SERCA) and calcium phosphate (PLB) protein expression in the ventricular remodeling process after myocardial infarction to explore the effect of gastrodin pretreatment on MIRI. MATERIAL AND METHODS Healthy 7-week-old male SD rats were randomly divided into a sham group (A), a model group (B), and gastrodin pretreatment groups C, D, and E (100, 200, and 400 mg/kg, respectively) with 20 in each group...
September 19, 2016: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
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