Synaptic mitochondria are more susceptible to Ca2+overload than nonsynaptic mitochondria.
AuthorsBrown MR, Sullivan PG, Geddes JW
JournalJ Biol Chem
PubMed ID16517608
'Mitochondria in nerve terminals are subjected to extensive Ca2+ fluxes and high energy demands, but the extent to which the synaptic mitochondria buffer Ca2+ is unclear. In this study, we identified a difference in the Ca2+ clearance ability of nonsynaptic versus synaptic mitochondrial populations enriched from rat cerebral cortex. Mitochondria ... More
Presynaptic Ca(2+) influx at the inhibitor of the crayfish neuromuscular junction: a photometric study at a high time resolution.
AuthorsVyshedskiy A, Lin JW
JournalJ Neurophysiol
PubMed ID10634895
'Presynaptic calcium influx at the inhibitor of the crayfish neuromuscular junction was investigated by measuring fluorescence transients generated by calcium-sensitive dyes. This approach allowed us to correlate presynaptic calcium influx with transmitter release at a high time resolution. Systematic testing of the calcium indicators showed that only low-affinity dyes, with ... More
Monitoring calcium in turtle hair cells with a calcium-activated potassium channel.
AuthorsTucker TR, Fettiplace R
JournalJ Physiol
PubMed ID8865061
'1. An apamin-sensitive Ca(2+)-activated K+ channel was characterized in turtle hair cells and utilized to monitor submembranous intracellular Ca2+ and to evaluate the concentration of the mobile endogenous calcium buffer. 2. Isolated hair cells were voltage clamped with whole-cell patch electrodes filled with a Cs(+)-based intracellular solution to block the ... More
Role of cytosolic Ca2+ in inhibition of InsP3-evoked Ca2+ release in Xenopus oocytes.
AuthorsIlyin V, Parker I
JournalJ Physiol
PubMed ID7932238
'1. Calcium liberation induced in Xenopus oocytes by flash photorelease of inositol 1,4,5-trisphosphate (InsP3) from a caged precursor was monitored by confocal microfluorimetry. The object was to determine whether inhibition of Ca2+ release seen with paired flashes arose as a direct consequence of elevated cytosolic free [Ca2+]. 2. Responses evoked ... More
Shift in the localization of sites of hydrogen peroxide production in brain mitochondria by mitochondrial stress.
AuthorsGyulkhandanyan AV, Pennefather PS
JournalJ Neurochem
PubMed ID15228597
'We have determined the underlying sites of H(2)O(2) generation by isolated rat brain mitochondria and how these can shift depending on the presence of respiratory substrates, electron transport chain modulators and exposure to stressors. H(2)O(2) production was determined using the fluorogenic Amplex red and peroxidase system. H(2)O(2) production was higher ... More
Bcl-2 potentiates the maximal calcium uptake capacity of neural cell mitochondria.
AuthorsMurphy AN, Bredesen DE, Cortopassi G, Wang E, Fiskum G
JournalProc Natl Acad Sci U S A
PubMed ID8790427
'Expression of the human protooncogene bcl-2 protects neural cells from death induced by many forms of stress, including conditions that greatly elevate intracellular Ca2+. Considering that Bcl-2 is partially localized to mitochondrial membranes and that excessive mitochondrial Ca2+ uptake can impair electron transport and oxidative phosphorylation, the present study tested ... More
Metabolism of inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate by the oocytes of Xenopus laevis.
AuthorsSims CE, Allbritton NL
JournalJ Biol Chem
PubMed ID9461597
'The pathway and kinetics of inositol 1,4,5-trisphosphate (IP3) metabolism were measured in Xenopus laevis oocytes and cytoplasmic extracts of oocytes. Degradation of microinjected IP3 in intact oocytes was similar to that in the extracts containing comparable concentrations of IP3 ([IP3]). The rate and route of metabolism of IP3 depended on ... More
Inositol trisphosphate-mediated Ca2+ influx into Xenopus oocytes triggers Ca2+ liberation from intracellular stores.
AuthorsYao Y, Parker I
JournalJ Physiol
PubMed ID8254510
'1. Inositol 1,4,5-trisphosphate (InsP3) functions as a second messenger by liberating Ca2+ from intracellular stores and by promoting influx of extracellular Ca2+. We examined whether Ca2+ influx modulates intracellular Ca2+ liberation in Xenopus oocytes by fluorescence monitoring of cytosolic free Ca2+ together with voltage clamp recording of Ca(2+)-activated Cl- membrane ... More
Uncoupling proteins 2 and 3 are fundamental for mitochondrial Ca2+ uniport.
AuthorsTrenker M, Malli R, Fertschai I, Levak-Frank S, Graier WF
JournalNat Cell Biol
PubMed ID17351641
'Mitochondrial Ca(2+) uptake is crucial for the regulation of the rate of oxidative phosphorylation, the modulation of spatio-temporal cytosolic Ca(2+) signals and apoptosis. Although the phenomenon of mitochondrial Ca(2+) sequestration, its characteristics and physiological consequences have been convincingly reported, the actual protein(s) involved in this process are unknown. Here, we ... More
Calmodulin-dependent regulation of inducible and neuronal nitric-oxide synthase.
AuthorsLee SJ, Stull JT
JournalJ Biol Chem
PubMed ID9765272
'Neuronal and endothelial nitric-oxide synthases depend upon Ca2+/calmodulin for activation, whereas the activity of the inducible nitric-oxide synthase is Ca2+-independent, presumably due to tightly bound calmodulin. To study these different mechanisms, a series of chimeras derived from neuronal and inducible nitric- oxide synthases were analyzed. Chimeras containing only the oxygenase ... More
Cross talk between metabotropic and ionotropic glutamate receptor-mediated signaling in parallel fiber-induced inositol 1,4,5-trisphosphate production in cerebellar Purkinje cells.
AuthorsOkubo Y, Kakizawa S, Hirose K, Iino M
JournalJ Neurosci
PubMed ID15509738
'In many excitatory glutamatergic synapses, both ionotropic glutamate receptors (iGluRs) and metabotropic glutamate receptors (mGluRs) are closely distributed on the postsynaptic membrane. However, the functional significance of the close distribution of the two types of glutamate receptors has not been fully clarified. In this study, we examined the functional interaction ... More
Axonal calcium entry during fast 'sodium' action potentials in rat cerebellar Purkinje neurones.
AuthorsCallewaert G, Eilers J, Konnerth A
JournalJ Physiol
PubMed ID8887772
'1. Using laser-scanning confocal microscopy, fast Ca2+ transients were recorded in individual not yet myelinated axons of Purkinje neurones in cerebellar slices from young rats. Axonal Ca2+ transients could be detected during a single action potential and had progressively larger amplitudes when the number of action potentials was increased. 2. ... More
Spatial heterogeneity of intracellular Ca2+ signals in axons of basket cells from rat cerebellar slices.
AuthorsLlano I, Tan YP, Caputo C
JournalJ Physiol
PubMed ID9279804
'1. Using tight-seal whole-cell recording and digital fluorescence imaging, we studied intracellular calcium (Ca2+i) dynamics in cerebellar basket cells, whose dendrites, axon and presynaptic terminals are coplanar, an optimal configuration for simultaneous optical measurements of all functional domains. 2. In Cs(+)-loaded neurones, depolarizing pulses induced large Ca2+i transients in single ... More
Mitochondria are excitable organelles capable of generating and conveying electrical and calcium signals.
AuthorsIchas F, Jouaville LS, Mazat JP
JournalCell
PubMed ID9215636
'We report Ca2(+)-induced release of Ca2+ from mitochondria (mCICR) dependent on transitory opening of the permeability transition pore (PTP) operating in a low conductance mode. The Ca2+ fluxes taking place during mCICR are a direct consequence of the mitochondrial depolarization spike (mDPS) caused by PTP opening. Both mDPS and mCICR ... More
Optical nanosensors for chemical analysis inside single living cells. 2. Sensors for pH and calcium and the intracellular application of PEBBLE sensors.
AuthorsClark HA, Kopelman R, Tjalkens R, Philbert MA
JournalAnal Chem
PubMed ID10565275
'Optical nanosensors, or PEBBLEs (probes encapsulated by biologically localized embedding), have been produced for intracellular measurements of pH and calcium. Five varieties of pH-sensitive sensors and three different calcium-selective sensors are presented and discussed. Each sensor combines an ion-selective fluorescent indicator and an ion-insensitive internal standard entrapped within an acrylamide ... More
Elementary events of InsP3-induced Ca2+ liberation in Xenopus oocytes: hot spots, puffs and blips.
AuthorsParker I, Choi J, Yao Y
JournalCell Calcium
PubMed ID8889202
'Liberation of sequestered Ca2+ ions in Xenopus oocytes by the second messenger inositol 1,4,5-trisphosphate (InP3) occurs from functionally discrete sites, which are spaced at intervals of several microns and probably represent clusterings of InsP3 receptor/channels (InsP3R) in the endoplasmic reticulum. As well as requiring InsP3, opening of release channels is ... More
Localization of the site of Ca2+ release at the level of a single sarcomere in skeletal muscle fibres.
'The development of mechanical force in skeletal muscle fibres is brought about by rapid increases in the intracellular calcium concentration (Ca2+ transients) which can be detected by optical methods. Local stimulation experiments and ultrastructural evidence suggest that, at a microscopic level, these Ca2+ transients are generated by the release of ... More
Fast kinetics of calcium liberation induced in Xenopus oocytes by photoreleased inositol trisphosphate.
AuthorsParker I, Yao Y, Ilyin V
JournalBiophys J
PubMed ID8770200
'Inositol 1,4,5-trisphosphate (InsP3) acts on intracellular receptors to cause liberation of Ca2+ ions into the cytosol as repetitive spikes and propagating waves. We studied the processes underlying this regenerative release of Ca2+ by monitoring with high resolution the kinetics of Ca2+ flux evoked in Xenopus oocytes by flash photolysis of ... More
Regulation of the permeability transition pore in skeletal muscle mitochondria. Modulation By electron flow through the respiratory chain complex i.
AuthorsFontaine E, Eriksson O, Ichas F, Bernardi P
JournalJ Biol Chem
PubMed ID9575229
'We have investigated the regulation of the permeability transition pore (PTP), a cyclosporin A-sensitive channel, in rat skeletal muscle mitochondria. As is the case with mitochondria isolated from a variety of sources, skeletal muscle mitochondria can undergo a permeability transition following Ca2+ uptake in the presence of Pi. We find ... More
The light response of Drosophila photoreceptors is accompanied by an increase in cellular calcium: effects of specific mutations.
AuthorsPeretz A, Suss-Toby E, Rom-Glas A, Arnon A, Payne R, Minke B
JournalNeuron
PubMed ID8011336
'Photoreceptors of dissociated Drosophila retinae were loaded with the fluorescent Ca2+ indicators, fluo-3 and Calcium Green-5N. In fluo-3-loaded, wild-type photoreceptors, a rapid increase in fluorescence (Ca2+ signal) accompanied the light-evoked inward current. Removal of extracellular Ca2+ greatly reduced the Ca2+ signal, indicating Ca2+ influx as its major cause. In Calcium ... More
Calcium green-5N, a novel fluorescent probe for monitoring high intracellular free Ca2+ concentrations associated with glutamate excitotoxicity in cultured rat brain neurons.
AuthorsRajdev S, Reynolds IJ
JournalNeurosci Lett
PubMed ID7907171
We describe here the properties of calcium green-5N (CG5N), a novel Ca(2+)-sensitive fluorescent probe. CG5N binds Ca2+ with an affinity of 4.29 +/- 0.67 microM. Ca2+ binding is associated with a 14.7-fold increase in fluorescence. Mg2+ binds to CG5N with an affinity of 5 mM but produces a very small ... More
Notch activity acts as a sensor for extracellular calcium during vertebrate left-right determination.
AuthorsRaya A, Kawakami Y, Rodríguez-Esteban C, Ibañes M, Rasskin-Gutman D, Rodríguez-León J, Büscher D, Feijó JA, Izpisúa Belmonte JC
JournalNature
PubMed ID14712268
During vertebrate embryo development, the breaking of the initial bilateral symmetry is translated into asymmetric gene expression around the node and/or in the lateral plate mesoderm. The earliest conserved feature of this asymmetric gene expression cascade is the left-sided expression of Nodal, which depends on the activity of the Notch ... More
Confocal imaging of calcium microdomains and calcium extrusion in turtle hair cells.
AuthorsTucker T, Fettiplace R
JournalNeuron
PubMed ID8845156
We have studied spatial Ca2+ distribution in hair cells filled with the low affinity fluorescent indicator Calcium Green 5N using real-time confocal microscopy and whole-cell recording. During depolarizations lasting several hundred milliseconds, Ca2+ fluorescence increased at a number of hotspots around the base of the cell but changed little near ... More
Calcium pump kinetics determined in single erythrocyte ghosts by microphotolysis and confocal imaging.
AuthorsKubitscheck U, Pratsch L, Passow H, Peters R
JournalBiophys J
PubMed ID7669907
The activity of the plasma membrane calcium pump was measured in single cells. Human red blood cell ghosts were loaded with a fluorescent calcium indicator and either caged calcium and ATP (protocol A) or caged ATP and calcium (protocol B). In a suitably modified laser scanning microscope either calcium or ... More
Interactions between inositol trisphosphate receptors and fluorescent Ca2+ indicators.
AuthorsMorris SA, Correa V, Cardy TJ, O'Beirne G, Taylor CW
JournalCell Calcium
PubMed ID10326680
Fura-2 and BAPTA were previously shown to be competitive antagonists of inositol trisphosphate (InsP3) receptors, but for practical reasons the analyses were performed at pH 8.3. We recently developed a scintillation proximity assay (SPA) for pure cerebellar InsP3 receptors which allows low affinity interactions to be characterized and is readily ... More
T-jump study of calcium binding kinetics of calcium chelators.
AuthorsNaraghi M
JournalCell Calcium
PubMed ID9481476
Recent experimental studies have investigated the kinetic competition between calcium chelators and the secretion apparatus at a fast central synapse. Simultaneously, mathematical modelling studies indicate the importance of a quantitative knowledge of the binding kinetics of the chelators in studying fast physiological processes operating on a millisecond time scale. Using ... More
Two dye two wavelength excitation calcium imaging: results from bovine adrenal chromaffin cells.
AuthorsOheim M, Naraghi M, Müller TH, Neher E
JournalCell Calcium
PubMed ID9793690
We tested a mixture of Calcium-Green-1 (CG-1) and Brilliantsulfaflavine (BS) for dual excitation ratiometric measurements of the intracellular free calcium concentration ([Ca2+]i) in bovine adrenal chromaffin cells. Dyes were coloaded (without being molecularly linked to each other) in the whole-cell configuration of the patch clamp technique. We compared the loading ... More
Calcium signaling in a narrow somatic submembrane shell during synaptic activity in cerebellar Purkinje neurons.
AuthorsEilers J, Callewaert G, Armstrong C, Konnerth A
JournalProc Natl Acad Sci U S A
PubMed ID7479766
Temporal and spatial changes in the intracellular Ca2+ concentration ([Ca2+]i) were examined in dendrites and somata of rat cerebellar Purkinje neurons by combining whole-cell patch-clamp recording and fast confocal laser-scanning microscopy. In cells loaded via the patch pipette with the high-affinity Ca2+ indicator Calcium Green-1 (Kd approximately 220 nM), a ... More
Molecular characterization of S100A1-S100B protein in retina and its activation mechanism of bovine photoreceptor guanylate cyclase.
AuthorsDuda T, Goraczniak RM, Sharma RK
JournalBiochemistry
PubMed ID8639567
In contrast to the membrane guanylate cyclases which are stimulated by extracellular ligands, rod outer segment membrane guanylate cyclase (ROS-GC) activity is modulated intracellularly by calcium in two ways: one, where it is inhibited, and the other, where it is stimulated. The former way is linked to the phototransduction, and ... More
Properties of tri- and tetracarboxylate Ca2+ indicators in frog skeletal muscle fibers.
AuthorsZhao M, Hollingworth S, Baylor SM
JournalBiophys J
PubMed ID8789107
Recently a number of lower-affinity fluorescent Ca2+ indicators have become available with principal absorbance bands at visible wavelengths. This article evaluates these indicators, as well as two shorter wavelength indicators, mag-fura-5 and mag-indo-1, for their suitability as rapid Ca2+ indicators in frog skeletal muscle fibers. With three lower-affinity tricarboxylate indicators ... More
Relation between intracellular Ca2+ signals and Ca(2+)-activated Cl- current in Xenopus oocytes.
AuthorsParker I, Yao Y
JournalCell Calcium
PubMed ID8055544
Activation of inositol 1,4,5-trisphosphate (InsP3) signalling in Xenopus oocytes causes intracellular Ca2+ mobilization and thereby activates a Ca(2+)-dependent Cl- membrane conductance. Measurements of cytosolic Ca2+ levels using fluorescent indicators, however, revealed little correspondence with Cl- currents. Intracellular photorelease of InsP3 from a caged precursor evoked transient currents that peaked while ... More
A continuous fluorescence-based assay for the human high-molecular-weight cytosolic phospholipase A2.
AuthorsHuang Z, Laliberté F, Tremblay NM, Weech PK, Street IP
JournalAnal Biochem
PubMed ID7856835
A sensitive method for continuously monitoring the activity of the human cytosolic phospholipase A2 (cPLA2) is described. Recombinant cPLA2 efficiently hydrolyzes fatty acid esters of 7-hydroxycoumarin, producing the free fatty acid and the highly fluorescent 7-hydroxycoumarin. All of the observed 7-hydroxycoumarinyl ester hydrolase activity (7-HCEase) in a preparation of the ... More
Properties of filament-bound myosin light chain kinase.
AuthorsLin P, Luby-Phelps K, Stull JT
JournalJ Biol Chem
PubMed ID10026225
Myosin light chain kinase binds to actin-containing filaments from cells with a greater affinity than to F-actin. However, it is not known if this binding in cells is regulated by Ca2+/calmodulin as it is with F-actin. Therefore, the binding properties of the kinase to stress fibers were examined in smooth ... More
Modulation of Na+,Ca2+ exchange current by EGTA calcium buffering in giant cardiac membrane patches.
AuthorsKabakov AY, Hilgemann DW
JournalBiochim Biophys Acta
PubMed ID8541285
Effects of calcium buffering by EGTA were examined on sodium-calcium exchange currents (INaCa) in inside-out giant cardiac membrane patches. Free calcium concentrations (Ca2+) were monitored with a calcium electrode and a fluorescent calcium indicator (Calcium Green-5N). With 1.8 microM cytoplasmic Ca2+, inward INaCa increased 2-fold at -120 mV when EGTA ... More
L-Type Ca(2+) channel charge movement and intracellular Ca(2+) in skeletal muscle fibers from aging mice.
AuthorsWang ZM, Messi ML, Delbono O
JournalBiophys J
PubMed ID10733973
In this work we tested the hypothesis that skeletal muscle fibers from aging mice exhibit a significant decline in myoplasmic Ca(2+) concentration resulting from a reduction in L-type Ca(2+) channel (dihydropyridine receptor, DHPR) charge movement. Skeletal muscle fibers from the flexor digitorum brevis (FDB) muscle were obtained from 5-7-, 14-18-, ... More
Stimulation-induced changes in [Ca2+] in lizard motor nerve terminals.
AuthorsDavid G, Barrett JN, Barrett EF
JournalJ Physiol
PubMed ID9350620
1. Motor axons were injected ionophoretically with one of five Ca(2+)-sensitive dyes (fluo-3, Calcium Green-2, Calcium Green-5N, fluo-3FF and Oregon Green BAPTA-5N). Changes in fluorescence (delta F/Frest) within motor terminal boutons following a single action potential and brief stimulus trains were monitored with high temporal resolution using a confocal microscope. ... More
Ca2+ influx modulation of temporal and spatial patterns of inositol trisphosphate-mediated Ca2+ liberation in Xenopus oocytes.
AuthorsYao Y, Parker I
JournalJ Physiol
PubMed ID8046631
Inositol 1,4,5-trisphosphate (InsP3) functions as a second messenger by liberating intracellular Ca2+ and by promoting influx of extracellular Ca2+. We examined the effects of Ca2+ influx on the temporal and spatial patterns of intracellular Ca2+ liberation in Xenopus oocytes by fluorescence imaging of cytosolic free Ca2+ together with voltage clamp ... More
Synaptic differentiation of a single motor neuron: conjoint definition of transmitter release, presynaptic calcium signals, and ultrastructure.
AuthorsCooper RL, Marin L, Atwood HL
JournalJ Neurosci
PubMed ID7790906
The opener muscle in the walking legs of the crayfish (Procambarus clarkii) is innervated by only one excitatory motor neuron, yet excitatory postsynaptic potentials (EPSPs) of proximal fibers are eightfold larger than those of central muscle fibers at low frequencies of activation, due in large measure to differences in presynaptic ... More
Genetic dissection of light-induced Ca2+ influx into Drosophila photoreceptors.
AuthorsPeretz A, Sandler C, Kirschfeld K, Hardie RC, Minke B
JournalJ Gen Physiol
PubMed ID7699363
Invertebrate photoreceptors use the inositol-lipid signaling cascade for phototransduction. A useful approach to dissect this pathway and its regulation has been provided by the isolation of Drosophila visual mutants. We measured extracellular changes of Ca2+ [delta Ca2+]o in Drosophila retina using Ca(2+)-selective microelectrodes in both the transient receptor potential (trp) ... More
Calcium-dependent and -independent interfacial binding and catalysis of cytosolic group IV phospholipase A2.
AuthorsHixon MS, Ball A, Gelb MH
JournalBiochemistry
PubMed ID9622504
Cytosolic group IV phospholipase A2 (cPLA2) plays a role in liberating arachidonic acid from the sn-2 position of mammalian cellular phospholipids. The enzyme consists of a catalytic domain joined to an N-terminal calcium-dependent, membrane binding domain (C2 domain). The interfacial binding properties of the full-length, nonphosphorylated enzyme and its C2 ... More
Lysophosphatidylcholine modulates catalytically important motions of the Ca-ATPase phosphorylation domain.
AuthorsHunter GW, Bigelow DJ, Squier TC
JournalBiochemistry
PubMed ID10194382
Catalytically important motions of the Ca-ATPase, modulated by the physical properties of surrounding membrane phospholipids, have been suggested to be rate-limiting under physiological conditions. To identify the nature of the structural coupling between the Ca-ATPase and membrane phospholipids, we have investigated the functional and structural effects resulting from the incorporation ... More
Measurement of cytosolic Ca2+ concentration in Limulus ventral photoreceptors using fluorescent dyes.
Several Ca-sensitive fluorescent dyes (fura-2, mag-fura-2 and Calcium Green-5N) were used to measure intracellular calcium ion concentration, Cai, accompanying light-induced excitation of Limulus ventral nerve photoreceptors. A ratiometric procedure was developed for quantification of Calcium Green-5N fluorescence. A mixture of Calcium Green-5N and a Ca-insensitive dye, ANTS, was injected in ... More
Altered mitochondrial bioenergetics and ultrastructure in the skeletal muscle of young adults with type 1 diabetes.
Authors
JournalDiabetologia
PubMed ID29666899
Identification and functional validation of FDA-approved positive and negative modulators of the mitochondrial calcium uniporter.
Authors
JournalCell Rep
PubMed ID34161774
Structure and mechanism of the mitochondrial Ca2+ uniporter holocomplex.
Authors
JournalNature
PubMed ID32494073
Structures reveal gatekeeping of the mitochondrial Ca2+ uniporter by MICU1-MICU2.
Authors
JournalElife
PubMed ID32667285
Mitochondrial Ca2+ Signaling Is an Electrometabolic Switch to Fuel Phagosome Killing.
Authors
JournalCell Rep
PubMed ID33238121
MICU1 Confers Protection from MCU-Dependent Manganese Toxicity.
Authors
JournalCell Rep
PubMed ID30403999
Na+ controls hypoxic signalling by the mitochondrial respiratory chain.
Authors
JournalNature
PubMed ID32728214
Opening of the mitochondrial permeability transition pore links mitochondrial dysfunction to insulin resistance in skeletal muscle.
Authors
JournalMol Metab
PubMed ID24634818
Mechanisms of EMRE-Dependent MCU Opening in the Mitochondrial Calcium Uniporter Complex.
Authors
JournalCell Rep
PubMed ID33296646
Cysteine 202 of cyclophilin D is a site of multiple post-translational modifications and plays a role in cardioprotection.