-
Brain Research Bulletin Nov 2023Postoperative cognitive dysfunction (POCD) is characterized by impaired learning and memory. 6 h duration isoflurane anesthesia is an important factor to induce POCD,...
BACKGROUND
Postoperative cognitive dysfunction (POCD) is characterized by impaired learning and memory. 6 h duration isoflurane anesthesia is an important factor to induce POCD, and the dysfunction of ryanodine receptor (RyR) in the hippocampus may be involved in this process. We investigated the expression of RyR3 in the hippocampus of mice after 6-h duration isoflurane anesthesia, as well as the improvement of RyR receptor agonist caffeine on POCD mice, while attempting to identify the underlying molecular mechanism.
MATERIALS
We constructed a POCD model using 8-week-old male C57BL/6J mice that were exposed to 6-h duration isoflurane. Prior to the three-day cognitive behavioral experiment, RyR agonist caffeine were injected. Fear conditioning and location memory tests were used in behavioral studies. We also exposed the mouse neuroblastoma cell line Neuro-2a (N2A) to 6-h duration isoflurane exposure to simulate the conditions of in vivo cognitive dysfunction. We administered ryanodine receptor agonist (caffeine) and inhibitor (ryanodine) to N2a cells. Following that, we performed a series of bioinformatics analysis to discover proteins that are involved in the development of cognitive dysfunction. Rt-PCR and Western blot were used to assess mRNA level and protein expression.
RESULTS
6-h duration isoflurane anesthesia induced cognitive dysfunction and increased RyR3 mRNA levels in hippocampus. The mRNA levels of RyR3 in cultured N2a cells after anesthesia were comparable to those in vivo, and the RyR agonist caffeine corrected the expression of some cognitive-related phenotypic proteins that were disturbed after anesthesia. Intraperitoneal injection of RyR agonist caffeine can improve cognitive function after isoflurane anesthesia in mice, and bioinformatics analyses suggest that CaMKⅣ may be involved in the molecular mechanism.
CONCLUSION
Ryanodine receptor agonist caffeine may improve cognitive dysfunction in mice after isoflurane anesthesia.
Topics: Male; Mice; Animals; Isoflurane; Ryanodine Receptor Calcium Release Channel; Anesthetics, Inhalation; Caffeine; Mice, Inbred C57BL; Cognitive Dysfunction; Postoperative Cognitive Complications; RNA, Messenger; Hippocampus
PubMed: 37852420
DOI: 10.1016/j.brainresbull.2023.110790 -
The Journal of Physiology Jan 2023Enteroendocrine cells (EECs) are specialized sensors of luminal forces and chemicals in the gastrointestinal (GI) epithelium that respond to stimulation with a release...
Enteroendocrine cells (EECs) are specialized sensors of luminal forces and chemicals in the gastrointestinal (GI) epithelium that respond to stimulation with a release of signalling molecules such as serotonin (5-HT). For mechanosensitive EECs, force activates Piezo2 channels, which generate a very rapidly activating and inactivating (∼10 ms) cationic (Na , K , Ca ) receptor current. Piezo2 receptor currents lead to a large and persistent increase in intracellular calcium (Ca ) that lasts many seconds to sometimes minutes, suggesting signal amplification. However, intracellular calcium dynamics in EEC mechanotransduction remain poorly understood. The aim of this study was to determine the role of Ca stores in EEC mechanotransduction. Mechanical stimulation of a human EEC cell model (QGP-1) resulted in a rapid increase in cytoplasmic Ca and a slower decrease in ER stores Ca , suggesting the involvement of intracellular Ca stores. Comparing murine primary colonic EECs with colonocytes showed expression of intercellular Ca store receptors, a similar expression of IP receptors, but a >30-fold enriched expression of Ryr3 in EECs. In mechanically stimulated primary EECs, Ca responses decreased dramatically by emptying stores and pharmacologically blocking IP and RyR1/3 receptors. RyR3 genetic knockdown by siRNA led to a significant decrease in mechanosensitive Ca responses and 5-HT release. In tissue, pressure-induced increase in the Ussing short circuit current was significantly decreased by ryanodine receptor blockade. Our data show that mechanosensitive EECs use intracellular Ca stores to amplify mechanically induced Ca entry, with RyR3 receptors selectively expressed in EECs and involved in Ca signalling, 5-HT release and epithelial secretion. KEY POINTS: A population of enteroendocrine cells (EECs) are specialized mechanosensors of the gastrointestinal (GI) epithelium that respond to mechanical stimulation with the release of important signalling molecules such as serotonin. Mechanical activation of these EECs leads to an increase in intracellular calcium (Ca ) with a longer duration than the stimulus, suggesting intracellular Ca signal amplification. In this study, we profiled the expression of intracellular Ca store receptors and found an enriched expression of the intracellular Ca receptor Ryr3, which contributed to the mechanically evoked increases in intracellular calcium, 5-HT release and epithelial secretion. Our data suggest that mechanosensitive EECs rely on intracellular Ca stores and are selective in their use of Ryr3 for amplification of intracellular Ca . This work advances our understanding of EEC mechanotransduction and may provide novel diagnostic and therapeutic targets for GI motility disorders.
Topics: Mice; Animals; Humans; Ryanodine Receptor Calcium Release Channel; Ryanodine; Serotonin; Calcium; Receptors, Calcium-Sensing; Mechanotransduction, Cellular; Enteroendocrine Cells
PubMed: 36428286
DOI: 10.1113/JP283383 -
Journal of Agricultural and Food... Dec 2022Ryanodine receptor (RyR) is a giant calcium release channel located on the membrane of the endoplasmic reticulum (ER). Here, we report the regulation of RyRs from two...
Ryanodine receptor (RyR) is a giant calcium release channel located on the membrane of the endoplasmic reticulum (ER). Here, we report the regulation of RyRs from two major agricultural pests, diamondback moth and fall armyworm, by insect calmodulin (CaM). The recombinantly expressed full-length insect RyR could be pulled down by insect CaM in the presence of Ca, but the efficiency is lower compared to rabbit RyR1 and insect RyR with the CaM-binding domain (CaMBD) replaced by rabbit RyR1 sequence. Interestingly, the enhanced binding of CaM in the mutant insect RyR resulted in an increased sensitivity to the diamide insecticide chlorantraniliprole (CHL), suggesting that this CaM-CaMBD interface could be targeted by potential synergists acting as molecular glue. The thermodynamics of the binding between insect CaM and CaMBD was characterized by isothermal titration calorimetry, and the key residues responsible for the insect-specific regulation were identified through mutagenesis studies.
Topics: Animals; Rabbits; Calmodulin; Ryanodine Receptor Calcium Release Channel; Moths; Calcium Signaling; Protein Binding; Calcium
PubMed: 36524829
DOI: 10.1021/acs.jafc.2c07519 -
Cell Calcium Sep 2023The ryanodine receptor type 2 (RyR) is a key player in Ca handling during excitation-contraction coupling. During each heartbeat, RyR channels are responsible for...
The ryanodine receptor type 2 (RyR) is a key player in Ca handling during excitation-contraction coupling. During each heartbeat, RyR channels are responsible for linking the action potential with the contractile machinery of the cardiomyocyte by releasing Ca from the sarcoplasmic reticulum. RyR function is fine-tuned by associated signalling molecules, arrangement in clusters and subcellular localization. These parameters together define RyR function within microdomains and are subject to disease remodelling. This review describes the latest findings on RyR microdomain organization, the alterations with disease which result in increased subcellular heterogeneity and emergence of microdomains with enhanced arrhythmogenic potential, and presents novel technologies that guide future research to study and target RyR channels within specific microdomains.
PubMed: 37390591
DOI: 10.1016/j.ceca.2023.102769 -
Current Opinion in Structural Biology Aug 2016Ryanodine receptors (RyRs) are intracellular cation channels that mediate the rapid and voluminous release of Ca from the sarcoplasmic reticulum (SR) as required for... (Review)
Review
Ryanodine receptors (RyRs) are intracellular cation channels that mediate the rapid and voluminous release of Ca 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. Here we review recent advances in our understanding of RyR architecture and gating, and highlight remaining gaps in understanding which we anticipate will soon be filled.
Topics: Cryoelectron Microscopy; Ion Channel Gating; Ligands; Ryanodine Receptor Calcium Release Channel
PubMed: 27687475
DOI: 10.1016/j.sbi.2016.09.002 -
Circulation Research Jul 2021
Topics: Death, Sudden, Cardiac; Gain of Function Mutation; Humans; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum
PubMed: 34292783
DOI: 10.1161/CIRCRESAHA.121.319651 -
Frontiers in Cellular Neuroscience 2024Intracellular Ca-signaling in astrocytes is instrumental for their brain "housekeeping" role and astroglial control of synaptic plasticity. An important source for...
Intracellular Ca-signaling in astrocytes is instrumental for their brain "housekeeping" role and astroglial control of synaptic plasticity. An important source for elevating the cytosolic Ca level in astrocytes is a release from endoplasmic reticulum which can be triggered via two fundamental pathways: IP3 receptors and calcium-induced calcium release (CICR) mediated by Ca-sensitive ryanodine receptors (RyRs). While the physiological role for glial IP3 became a focus of intensive research and debate, ryanodine receptors received much less attention. We explored the role for ryanodine receptors in the modulation of cytosolic Ca-signaling in the cortical and hippocampal astrocytes, astrocyte-neuron communication and astroglia modulation of synaptic plasticity. Our data show that RyR-mediated Ca-induced Ca-release from ER brings substantial contribution into signaling in the functional microdomains hippocampal and neocortical astrocytes. Furthermore, RyR-mediated CICR activated the release of ATP and glutamate from hippocampal and neocortical astrocytes which, in turn, elicited transient purinergic and tonic glutamatergic currents in the neighboring pyramidal neurons. The CICR-facilitated release of ATP and glutamate was inhibited after intracellular perfusion of astrocytes with ryanodine and BAPTA and in the transgenic dnSNARE mice with impaired astroglial exocytosis. We also found out that RyR-mediated amplification of astrocytic Ca-signaling enhanced the long-term synaptic potentiation in the hippocampus and neocortex of aged mice. Combined, our data demonstrate that ryanodine receptors are essential for astrocytic Ca-signaling and efficient astrocyte-neuron communications. The RyR-mediated CICR contributes to astrocytic control of synaptic plasticity and can underlie, at least partially, neuroprotective and cognitive effects of caffein.
PubMed: 38812795
DOI: 10.3389/fncel.2024.1382010 -
American Journal of Physiology. Heart... Oct 2023Ryanodine receptor 2 (RyR2) hyperactivity is observed in structural heart diseases that are a result of ischemia or heart failure. It causes abnormal calcium handling...
Ryanodine receptor 2 (RyR2) hyperactivity is observed in structural heart diseases that are a result of ischemia or heart failure. It causes abnormal calcium handling and calcium leaks that cause metabolic, electrical, and mechanical dysfunction, which can trigger arrhythmias. Here, we tested the antiarrhythmic potential of dantrolene (RyR inhibitor) in human hearts. Human hearts not used in transplantation were obtained, and right ventricular outflow tract (RVOT) wedges and left ventricular (LV) slices were prepared. Pseudo-ECGs were recorded to determine premature ventricular contraction (PVC) incidences. Optical mapping was performed to determine arrhythmogenic substrates. After baseline optical recordings, tissues were treated with ) isoproterenol (250 nM), ) caffeine (200 mM), and ) dantrolene (2 or 10 mM). Optical recordings were obtained after each treatment. Isoproterenol and caffeine treatment increased PVC incidence, whereas dantrolene reduced the PVC burden. Isoproterenol shortened action potential duration (APD) in the RV, RVOT, and LV regions and shortened calcium transient duration (CaTD) in the LV. Caffeine further shortened APD in the RV, did not modulate APD in the RVOT, and prolonged APD in the LV. In addition, in the LV, CaTD prolongation was also observed. More importantly, adding dantrolene did not alter APD in the RV or RVOT regions but produced a trend toward APD prolongation and significant CaTD prolongation in the LV, restoring these parameters to baseline values. In conclusions, dantrolene treatment suppresses triggers and reverses arrhythmogenic substrates in the human heart and could be a novel antiarrhythmic therapy in patients with structural heart disease. Ryanodine receptor 2 hyperactivity is observed in structural heart diseases caused by ischemia or heart failure. It causes abnormal calcium leaks, which can trigger arrhythmias. To prevent arrhythmias, we applied dantrolene in human hearts ex vivo. Isoproterenol and caffeine treatment increased PVC incidence, whereas dantrolene reduced the PVC burden. Dantrolene treatment suppresses triggers and reverses arrhythmogenic substrates and could be a novel antiarrhythmic therapy in patients with structural heart disease.
Topics: Humans; Ryanodine Receptor Calcium Release Channel; Dantrolene; Isoproterenol; Ryanodine; Calcium; Caffeine; Arrhythmias, Cardiac; Anti-Arrhythmia Agents; Heart Failure; Action Potentials
PubMed: 37566110
DOI: 10.1152/ajpheart.00103.2023 -
The Journal of General Physiology Dec 2017Large-conductance Ca release channels known as ryanodine receptors (RyRs) mediate the release of Ca from an intracellular membrane compartment, the endo/sarcoplasmic... (Review)
Review
Large-conductance Ca release channels known as ryanodine receptors (RyRs) mediate the release of Ca 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. RyRs share ∼70% sequence identity, with the greatest sequence similarity in the C-terminal region that forms the transmembrane, ion-conducting domain comprising ∼500 amino acids. The remaining ∼4,500 amino acids form the large regulatory cytoplasmic "foot" structure. Experimental evidence for Ca, ATP, phosphorylation, and redox-sensitive sites in the cytoplasmic structure have been described. Exogenous effectors include the two Ca releasing agents caffeine and ryanodine. Recent work describing the near atomic structures of mammalian skeletal and cardiac muscle RyRs provides a structural basis for the regulation of the RyRs by their multiple effectors.
Topics: Animals; Calcium; Humans; Ion Channel Gating; Muscles; Ryanodine Receptor Calcium Release Channel
PubMed: 29122978
DOI: 10.1085/jgp.201711878 -
American Journal of Physiology. Heart... Jun 2017This perspective attempts to shed light on an old and not yet solved controversy in cardiac physiology, i.e., the impact of increasing ryanodine receptor (RyR)2 open... (Review)
Review
This perspective attempts to shed light on an old and not yet solved controversy in cardiac physiology, i.e., the impact of increasing ryanodine receptor (RyR)2 open probability on myocardial function. Based on an already proven myocyte model, it was shown that increasing RyR2 open probability results in a purely short-lived increase in Ca transient amplitude, and, therefore, it does not increase cardiac contractility. However, potentiation of RyR2 activity permanently enhances fractional Ca release, shifting the intracellular Ca transient versus sarcoplasmic reticulum (SR) Ca content curve to a new state of higher efficiency. This would allow the heart to maintain a given contractility despite a decrease in SR Ca content, to enhance contractility if SR Ca content is simultaneously preserved or to successfully counteract the effects of a negative inotropic intervention. Increasing ryanodine receptor (RyR)2 open probability does not increase cardiac contractility. However, RyR2 potentiation shifts the intracellular Ca transient-sarcoplasmic reticulum (SR) Ca content relationship toward an enhanced efficiency state, which may contribute to a positive inotropic effect, preserve contractility despite decreased SR Ca content, or successfully counteract the effects of a negative inotropic action.
Topics: Animals; Calcium Signaling; Humans; Ion Channel Gating; Kinetics; Membrane Potentials; Models, Cardiovascular; Myocardial Contraction; Myocytes, Cardiac; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum
PubMed: 28389603
DOI: 10.1152/ajpheart.00855.2016