scholarly journals Subcellular Ca2+ signaling in the heart: the role of ryanodine receptor sensitivity

2010 ◽  
Vol 136 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Benjamin L. Prosser ◽  
Christopher W. Ward ◽  
W.J. Lederer
Keyword(s):  
Ryanodine Receptor ◽  
Receptor Sensitivity

Abstract 11423: Mitochondrial Calcium Flux Modulates Pacemaker Activity in Mouse Stem Cell Derived Cardiomyocytes

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
An Xie ◽  
Anyu Zhou ◽  
Hong Liu ◽  
Guangbin Shi ◽  
Kenneth R Boheler ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Mrna Level ◽  
Embryonic Stem ◽  
Calcium Flux ◽  
Pacemaker Activity ◽  
Receptor Subtypes ◽  
Ip3 Receptors ◽  
Cell Current ◽  
Beating Rate

INTRODUCTION: Ca2+ release from sarcoplasmic reticulum (SR) is known to contribute to the pacemaker activity in embryonic stem cells (ESC) derived cardiomyocytes (CMs). Mitochondria are known to participate in Ca2+ cycling. Nevertheless, the role of mitochondria in pacemaker activity is unclear. We studied the role of mitochondrial Ca2+ flux in spontaneously activity of ESC derived CMs. METHODS: CMs were derived from Wt and ryanodine receptor type 2 knockout (RYR2-/-) mouse ESC. Action potentials (APs) were recorded by perforated whole-cell current-clamp. Cytoplasmic and mitochondrial Ca2+ transients were determined by Fluo-4 and Rhod-2 respectively. Mitochondrial Ca2+ uniporter (MCU) siRNA was used. The mRNA level was evaluated by qPCR. RESULTS: As predicted, SR Ca2+ handling inhibitors, 10 μM ryanodine and 2 μM 2-APB, reduced spontaneous beating rate to 56% and 73% respectively in Wt CMs. Inhibition of mitochondrial Ca2+ flux by 10 μM Ru360 showed a similar inhibition effect on the pacemaker activity as 2 μM 2-APB in Wt CMs. To isolate the mitochondrial component, we used RYR2-/- CMs. In these cells, MCU inhibition by pharmacological or molecular biological means reduced beating rate. The MCU mRNA decreased by 96% after MCU siRNA silence 72 hrs (p<0.01). AP and mitochondrial Ca2+ transient synchronous recording revealed that the reduction of spontaneous beating rate accompanied with the depressed mitochondrial Ca2+ uptaking and releasing. In RyR2-/- CMs, 2 μM 2-APB could significantly lower the spontaneous beating rate. While 2 μM 2-APB was applied to MCU silenced RyR2-/- CMs, the beating rate couldn’t be slowed down further. This indicated IP3 receptors reduced spontaneous beating rate via MCU. Thapsigargin could substantially slow down beating rate like 2-APB. Caffeine depletion experiments showed other ryanodine receptor subtypes didn’t contribute Ca2+ release in RyR2-/- CMs. A L-type Ca2+ channel block, 10 μM nifedipine, couldn’t reduce beating frequency. This indicated spontaneous beating rate is Ca2+ influx independent in RyR2-/- CMs. CONCLUSIONS: Mitochondrial Ca2+ handling plays an important role in decreasing spontaneous beating rate. IP3R reduced spontaneous beating rate through MCU.

scholarly journals Evidence for the transport of glutathione through ryanodine receptor channel type 1

2003 ◽  
Vol 376 (3) ◽  
pp. 807-812 ◽  
Author(s):  
Gábor BÁNHEGYI ◽  
Miklós CSALA ◽  
Gábor NAGY ◽  
Vincenzo SORRENTINO ◽  
Rosella FULCERI ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Skeletal Muscles ◽  
Ruthenium Red ◽  
Lanthanum Chloride ◽  
Human Embryonic Kidney ◽  
Hek 293 ◽  
Channel Type ◽  
Receptor Channel

In the present study, we have investigated the role of RyR1 (ryanodine receptor calcium channel type 1) in glutathione (GSH) transport through the sarcoplasmic reticulum (SR) membrane of skeletal muscles. Lanthanum chloride, a prototypic blocker of cation channels, inhibited the influx and efflux of GSH in SR vesicles. Using a rapid-filtration-based assay and lanthanum chloride as a transport blocker, an uptake of radiolabelled GSH into SR vesicles was observed. Pretreatment of SR vesicles with the RyR1 antagonists Ruthenium Red and ryanodine as well as with lanthanum chloride blocked the GSH uptake. An SR-like GSH uptake appeared in microsomes obtained from an HEK-293 (human embryonic kidney 293) cell line after transfection of RyR1. These observations strongly suggest that RyR1 mediates GSH transport through the SR membranes of skeletal muscles.

scholarly journals Role of Amino-terminal Half of the S4-S5 Linker in Type 1 Ryanodine Receptor (RyR1) Channel Gating

2011 ◽  
Vol 286 (41) ◽  
pp. 35571-35577 ◽  
Author(s):  
Takashi Murayama ◽  
Nagomi Kurebayashi ◽  
Toshiharu Oba ◽  
Hideto Oyamada ◽  
Katsuji Oguchi ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Single Channel ◽  
Signal Transmission ◽  
Channel Gating ◽  
Helical Structure ◽  
Release Channel ◽  
Amino Terminal ◽  
Molecular Events

The type 1 ryanodine receptor (RyR1) is a Ca2+ release channel found in the sarcoplasmic reticulum of skeletal muscle and plays a pivotal role in excitation-contraction coupling. The RyR1 channel is activated by a conformational change of the dihydropyridine receptor upon depolarization of the transverse tubule, or by Ca2+ itself, i.e. Ca2+-induced Ca2+ release (CICR). The molecular events transmitting such signals to the ion gate of the channel are unknown. The S4-S5 linker, a cytosolic loop connecting the S4 and S5 transmembrane segments in six-transmembrane type channels, forms an α-helical structure and mediates signal transmission in a wide variety of channels. To address the role of the S4-S5 linker in RyR1 channel gating, we performed alanine substitution scan of N-terminal half of the putative S4-S5 linker (Thr4825–Ser4829) that exhibits high helix probability. The mutant RyR1 was expressed in HEK cells, and CICR activity was investigated by caffeine-induced Ca2+ release, single-channel current recordings, and [3H]ryanodine binding. Four mutants (T4825A, I4826A, S4828A, and S4829A) had reduced CICR activity without changing Ca2+ sensitivity, whereas the L4827A mutant formed a constitutive active channel. T4825I, a disease-associated mutation for malignant hyperthermia, exhibited enhanced CICR activity. An α-helical wheel representation of the N-terminal S4-S5 linker provides a rational explanation to the observed activities of the mutants. These results suggest that N-terminal half of the S4-S5 linker may form an α-helical structure and play an important role in RyR1 channel gating.

scholarly journals Common genes associated with antidepressant response in mouse and man identify key role of glucocorticoid receptor sensitivity

PLoS Biology ◽  
2017 ◽  
Vol 15 (12) ◽  
pp. e2002690 ◽  
Author(s):  
Tania Carrillo-Roa ◽  
Christiana Labermaier ◽  
Peter Weber ◽  
David P. Herzog ◽  
Caleb Lareau ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Antidepressant Response ◽  
Receptor Sensitivity

scholarly journals The role of ryanodine receptor type 3 in a mouse model of Alzheimer disease

Channels ◽  
2014 ◽  
Vol 8 (3) ◽  
pp. 230-242 ◽  
Author(s):  
Jie Liu ◽  
Charlene Supnet ◽  
Suya Sun ◽  
Hua Zhang ◽  
Levi Good ◽  
...  
Keyword(s):  
Alzheimer Disease ◽  
Mouse Model ◽  
Ryanodine Receptor ◽  
Receptor Type ◽  
Type 3

Ryanodine receptor function in newborn rat heart

2005 ◽  
Vol 288 (5) ◽  
pp. H2527-H2540 ◽  
Author(s):  
Claudia G. Pérez ◽  
Julio A. Copello ◽  
Yanxia Li ◽  
Kimberly L. Karko ◽  
Leticia Gómez ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
Functional Properties ◽  
Rat Heart ◽  
Single Channel ◽  
Binding Assays ◽  
Adult Rats ◽  
Intracellular Ca ◽  
Cardiac Excitation

The role of ryanodine receptor (RyR) in cardiac excitation-contraction (E-C) coupling in newborns (NB) is not completely understood. To determine whether RyR functional properties change during development, we evaluated cellular distribution and functionality of sarcoplasmic reticulum (SR) in NB rats. Sarcomeric arrangement of immunostained SR Ca2+-ATPase (SERCA2a) and the presence of sizeable caffeine-induced Ca2+ transients demonstrated that functional SR exists in NB. E-C coupling properties were then defined in NB and compared with those in adult rats (AD). Ca2+ transients in NB reflected predominantly sarcolemmal Ca2+ entry, whereas the RyR-mediated component was ∼13%. Finally, the RyR density and functional properties at the single-channel level in NB were compared with those in AD. Ligand binding assays revealed that in NB, RyR density can be up to 36% of that found in AD, suggesting that some RyRs do not contribute to the Ca2+ transient. To test the hypothesis that RyR functional properties change during development, we incorporated single RyRs into lipid bilayers. Our results show that permeation and gating kinetics of NB RyRs are identical to those of AD. Also, endogenous ligands had similar effects on NB and AD RyRs: sigmoidal Ca2+ dependence, stronger Mg2+-induced inhibition at low cytoplasmic Ca2+ concentrations, comparable ATP-activating potency, and caffeine sensitivity. These observations indicate that NB rat heart contains fully functional RyRs and that the smaller contribution of RyR-mediated Ca2+ release to the intracellular Ca2+ transient in NB is not due to different single RyR channel properties or to the absence of functional intracellular Ca2+ stores.

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