Increased [Mg2+]o reduces Ca2+ influx and disruption of mitochondrial membrane potential during reoxygenation.
AuthorsSharikabad MN, Ostbye KM, Brørs O
JournalAm J Physiol Heart Circ Physiol
PubMed ID11668073
'Increase in extracellular Mg2+ concentration ([Mg2+]o) reduces Ca2+ accumulation during reoxygenation of hypoxic cardiomyocytes and exerts protective effects. The aims of the present study were to investigate the effect of increased [Mg(2+)](o) on Ca2+ influx and efflux, free cytosolic Ca2+ ([Ca2+]i) and Mg2+ concentrations ([Mg2+]i), Ca2+ accumulation in the presence ... More
Defective pancreatic beta-cell glycolytic signaling in hepatocyte nuclear factor-1alpha-deficient mice.
AuthorsDukes ID, Sreenan S, Roe MW, Levisetti M, Zhou YP, Ostrega D, Bell GI, Pontoglio M, Yaniv M, Philipson L, Polonsky KS
JournalJ Biol Chem
PubMed ID9733737
'Mutations in the hepatocyte nuclear factor-1alpha (HNF-1alpha) gene cause maturity onset diabetes of the young type 3, a form of type 2 diabetes mellitus. In mice lacking the HNF-1alpha gene, insulin secretion and intracellular calcium ([Ca2+]i) responses were impaired following stimulation with nutrient secretagogues such as glucose and glyceraldehyde but ... More
Contributions of residual calcium to fast synaptic transmission.
AuthorsChen C, Regehr WG
JournalJ Neurosci
PubMed ID10414955
'Fast neurotransmitter release is driven by high calcium (10-100 microM) near open channels (Ca(local)), followed by a much smaller (<1 microM), longer-lasting residual calcium (Ca(res)). The most prominent component of release, phasic release, lasts several milliseconds and is thought to be triggered by Ca(local). A transient tail of release then ... More
adPEO mutations in ANT1 impair ADP-ATP translocation in muscle mitochondria.
'Mutations in the heart and muscle isoform of adenine nucleotide translocator 1 (ANT1) are associated with autosomal-dominant progressive external opthalmoplegia (adPEO) clinically characterized by exercise intolerance, ptosis and muscle weakness. The pathogenic mechanisms underlying the mitochondrial myopathy caused by ANT1 mutations remain largely unknown. In yeast, expression of ANT1 carrying ... More
Hair bundles are specialized for ATP delivery via creatine kinase.
AuthorsShin JB, Streijger F, Beynon A, Peters T, Gadzala L, McMillen D, Bystrom C, Van der Zee CE, Wallimann T, Gillespie PG,
JournalNeuron
PubMed ID17270734
'When stimulated strongly, a hair cell''s mechanically sensitive hair bundle may consume ATP too rapidly for replenishment by diffusion. To provide a broad view of the bundle''s protein complement, including those proteins participating in energy metabolism, we used shotgun mass spectrometry methods to identify proteins of purified chicken vestibular bundles. ... More
Identification of the magnesium-binding domain of the high-affinity ATP-binding site of the Bacillus subtilis and Escherichia coli SecA protein.
Authorsvan der Wolk JP, Klose M, de Wit JG, den Blaauwen T, Freudl R, Driessen AJ
JournalJ Biol Chem
PubMed ID7642557
'The homodimeric SecA protein is the peripheral subunit of the translocase, and couples the hydrolysis of ATP to the translocation of precursor proteins across the bacterial cytoplasmic membrane. The high affinity ATP binding activity of SecA resides in the amino-terminal domain of SecA. This domain contains a tandem repeat of ... More
Mitochondrial Ca(2+) uptake depends on the spatial and temporal profile of cytosolic Ca(2+) signals.
AuthorsCollins TJ, Lipp P, Berridge MJ, Bootman MD
JournalJ Biol Chem
PubMed ID11333261
'Using confocal imaging of Rhod-2-loaded HeLa cells, we examined the ability of mitochondria to sequester Ca(2+) signals arising from different sources. Mitochondrial Ca(2+) (Ca(2+)mit) uptake was stimulated by inositol 1,4,5-trisphosphate (InsP(3))-evoked Ca(2+) release, capacitative Ca(2+) entry, and Ca(2+) leaking from the endoplasmic reticulum. For each Ca(2+) source, the relationship between ... More
The function of mitochondria in presynaptic development at the neuromuscular junction.
AuthorsLee CW, Peng HB,
JournalMol Biol Cell
PubMed ID17942598
'Mitochondria with high membrane potential (DeltaPsi(m)) are enriched in the presynaptic nerve terminal at vertebrate neuromuscular junctions, but the exact function of these localized synaptic mitochondria remains unclear. Here, we investigated the correlation between mitochondrial DeltaPsi(m) and the development of synaptic specializations. Using mitochondrial DeltaPsi(m)-sensitive probe JC-1, we found that ... More
'We report that activation of GABA(A) receptors on cerebellar granule cell axons modulates both transmitter release and the excitability of the axon and soma. Axonal GABA(A) receptors depolarize the axon, increasing its excitability and causing calcium influx at axonal varicosities. GABA-mediated subthreshold depolarizations in the axon spread electrotonically to the ... More
Targeted bulk-loading of fluorescent indicators for two-photon brain imaging in vivo.
AuthorsGaraschuk O, Milos RI, Konnerth A
JournalNat Protoc
PubMed ID17406260
'One of the challenges for modern neuroscience is to understand the rules of concerted neuronal function in vivo. This question can be addressed using noninvasive high-resolution imaging techniques like two-photon microscopy. This protocol describes a versatile approach for in vivo two-photon calcium imaging of neural networks, stained with membrane-permeant fluorescent-indicator ... More
Oxidant-induced inhibition of the plasma membrane Ca2+-ATPase in pancreatic acinar cells: role of the mitochondria.
AuthorsBaggaley EM, Elliott AC, Bruce JI,
JournalAm J Physiol Cell Physiol
PubMed ID18787078
Impairment of the normal spatiotemporal pattern of intracellular Ca(2+) ([Ca(2+)](i)) signaling, and in particular, the transition to an irreversible
Actin-ATP hydrolysis is a major energy drain for neurons.
AuthorsBernstein BW, Bamburg JR
JournalJ Neurosci
PubMed ID12514193
In cultured chick ciliary neurons, when ATP synthesis is inhibited, ATP depletion is reduced approximately 50% by slowing actin filament turnover with jasplakinolide or latrunculin A. Jasplakinolide inhibits actin disassembly, and latrunculin A prevents actin assembly by sequestering actin monomers. Cytochalasin D, which allows assembly-disassembly, but only at pointed ends, ... More
Biphasic action of axonal GABA-A receptors on presynaptic calcium influx.
AuthorsStell BM,
JournalJ Neurophysiol
PubMed ID21471393
Although ionotropic ?-aminobutyric acid A receptors (GABA(A)Rs) have long been known to exist on the axons of many different cells, their effect on axon excitability and synaptic transmission remains controversial. Here, using high-speed Ca(2+) imaging, it is shown that they induce a biphasic effect in parallel fibers of the cerebellar ... More
Monitoring presynaptic calcium dynamics in projection fibers by in vivo loading of a novel calcium indicator.
AuthorsKreitzer AC, Gee KR, Archer EA, Regehr WG
JournalNeuron
PubMed ID10939328
Fluorometric calcium measurements have revealed presynaptic residual calcium (Ca(res)) to be an important regulator of synaptic strength. However, in the mammalian brain, it has not been possible to monitor Ca(res) in fibers that project from one brain region to another. Here, we label neuronal projections by injecting dextran-conjugated calcium indicators ... More
Postnatal loss of p/q-type channels confined to rhombic-lip-derived neurons alters synaptic transmission at the parallel fiber to purkinje cell synapse and replicates genomic cacna1a mutation phenotype of ataxia and seizures in mice.
Ataxia, episodic dyskinesia, and thalamocortical seizures are associated with an inherited loss of P/Q-type voltage-gated Ca(2+) channel function. P/Q-type channels are widely expressed throughout the neuraxis, obscuring identification of the critical networks underlying these complex neurological disorders. We showed recently that the conditional postnatal loss of P/Q-type channels in cerebellar ... More
Adaptive regulation maintains posttetanic potentiation at cerebellar granule cell synapses in the absence of calcium-dependent PKC.
AuthorsFioravante D, Myoga MH, Leitges M, Regehr WG,
JournalJ Neurosci
PubMed ID22993418
Posttetanic potentiation (PTP) is a transient, calcium-dependent increase in the efficacy of synaptic transmission following elevated presynaptic activity. The calcium-dependent protein kinase C (PKC(Ca)) isoforms PKCa and PKCß mediate PTP at the calyx of Held synapse, with PKCß contributing significantly more than PKCa. It is not known whether PKC(Ca) isoforms ... More
Activation of metabotropic GABA receptors increases the energy barrier for vesicle fusion.
Neurotransmitter release from presynaptic terminals is under the tight control of various metabotropic receptors. We report here that in addition to the regulation of Ca(2+) channel activity, metabotropic GABA(B) receptors (GABA(B)Rs) at murine hippocampal glutamatergic synapses utilize an inhibitory pathway that directly targets the synaptic vesicle release machinery. Acute application ... More
The neurogenic basic helix-loop-helix transcription factor NeuroD6 confers tolerance to oxidative stress by triggering an antioxidant response and sustaining the mitochondrial biomass.
AuthorsUittenbogaard M, Baxter KK, Chiaramello A,
JournalASN Neuro
PubMed ID20517466
Preserving mitochondrial mass, bioenergetic functions and ROS (reactive oxygen species) homoeostasis is key to neuronal differentiation and survival, as mitochondria produce most of the energy in the form of ATP to execute and maintain these cellular processes. In view of our previous studies showing that NeuroD6 promotes neuronal differentiation and ... More
Forward operation of adenine nucleotide translocase during F0F1-ATPase reversal: critical role of matrix substrate-level phosphorylation.
In pathological conditions, F(0)F(1)-ATPase hydrolyzes ATP in an attempt to maintain mitochondrial membrane potential. Using thermodynamic assumptions and computer modeling, we established that mitochondrial membrane potential can be more negative than the reversal potential of the adenine nucleotide translocase (ANT) but more positive than that of the F(0)F(1)-ATPase. Experiments on ... More
Fluorescent measurement of [Ca²?]c: basic practical considerations.
AuthorsSimpson AW,
JournalMethods Mol Biol
PubMed ID23007577
There is a vast array of dyes currently available for measurement of cytosolic calcium. These encompass single and dual excitation and single and dual emission probes. The choice of particular probe depends on the experimental question and the type of equipment to be used. It is therefore extremely difficult to ... More
Caffeine interaction with fluorescent calcium indicator dyes.
AuthorsMuschol M, Dasgupta BR, Salzberg BM
JournalBiophys J
PubMed ID10388782
We report that caffeine, in millimolar concentrations, interacts strongly with four common calcium indicator dyes: mag-fura-2, magnesium green, fura-2, and fluo-3. Fluorescence intensities are either noticeably enhanced (mag-fura-2, fura-2) or diminished (magnesium green, fluo-3). The caffeine-induced changes in the fluorescence spectra are clearly distinct from those of metal ion binding ... More
Intracellular Mg2+ surge follows Ca2+ increase during depolarization in cultured neurons.
AuthorsGotoh H, Kajikawa M, Kato H, Suto K
JournalBrain Res
PubMed ID10320737
The intracellular magnesium and calcium concentrations in cultured dorsal root ganglion neurons were measured using a fluorescent Mg2+ indicator, Mag-Fura-2 and a Ca2+ indicator, Fura-2, respectively. The magnesium concentration in the cytoplasm was higher than that in the nuclei at rest; 0.68+/-0.10 mM (mean+/-S.E.M., n=7) in the cytoplasm and 0.11+/-0.05 ... More
Hibernation during hypoxia in cardiomyocytes. Role of mitochondria as the O2 sensor.
During myocardial hibernation, decreases in coronary perfusion elicit inhibition of contraction, suggesting that energy demand is attenuated. We previously found an inhibition of contraction and O2 consumption during hypoxia (3% O2; PO2 = 20 torr for >2 h) in cardiomyocytes, which was reversible after reoxygenation. This study sought to determine ... More
Determinants of the time course of facilitation at the granule cell to Purkinje cell synapse.
AuthorsAtluri PP, Regehr WG
JournalJ Neurosci
PubMed ID8795622
Short-term facilitation is a widely observed form of synaptic enhancement that is not well understood. Although presynaptic calcium has long been implicated in this process, its role is unclear, particularly at synapses in the mammalian brain. We tested the role of presynaptic residual free calcium ([Ca]res) in facilitation of synapses ... More
Zinc permeates mouse muscle ACh receptor channels expressed in BOSC 23 cells and affects channel function.
AuthorsRagozzino D, Giovannelli A, Degasperi V, Eusebi F, Grassi F
JournalJ Physiol
PubMed ID11080253
1. The influx of Zn2+ through the channels of fetal and adult mouse muscle nicotinic acetylcholine receptors (gamma- and epsilon-AChRs) and its effects on receptor function were studied in transiently transfected human BOSC 23 cells, by combining patch-clamp recordings with digital fluorescence microscopy. 2. ACh-induced whole-cell currents were reversibly reduced ... More
Overexpression of Bcl-x(L) in beta-cells prevents cell death but impairs mitochondrial signal for insulin secretion.
AuthorsZhou YP, Pena JC, Roe MW, Mittal A, Levisetti M, Baldwin AC, Pugh W, Ostrega D, Ahmed N, Bindokas VP, Philipson LH, Hanahan D, Thompson CB, Polonsky KS
JournalAm J Physiol Endocrinol Metab
PubMed ID10662719
To study effects of Bcl-x(L) in the pancreatic beta-cell, two transgenic lines were produced using different forms of the rat insulin promoter. Bcl-x(L) expression in beta-cells was increased 2- to 3-fold in founder (Fd) 1 and over 10-fold in Fd 2 compared with littermate controls. After exposure to thapsigargin (10 ... More
Presynaptic calcium measurements at physiological temperatures using a new class of dextran-conjugated indicators.
AuthorsBeierlein M, Gee KR, Martin VV, Regehr WG
JournalJ Neurophysiol
PubMed ID15212445
Presynaptic calcium (Ca(pre)) has been studied extensively because of its role in triggering and modulating neurotransmitter release. Although calcium regulation and calcium-driven processes can be strongly temperature dependent, technical difficulties have limited most studies of Ca(pre) to temperatures well below the physiological range. Here we assessed the use of membrane-permeant ... More
Zinc-dependent structural stability of human Sonic hedgehog.
AuthorsDay ES, Wen D, Garber EA, Hong J, Avedissian LS, Rayhorn P, Shen W, Zeng C, Bailey VR, Reilly JO, Roden JA, Moore CB, Williams KP, Galdes A, Whitty A, Baker DP
JournalBiochemistry
PubMed ID10555969
The role of the zinc site in the N-terminal fragment of human Sonic hedgehog (ShhN) was explored by comparing the biophysical and functional properties of wild-type ShhN with those of mutants in which the zinc-coordinating residues H140, D147, and H182, or E176 which interacts with the metal ion via a ... More
The relationship between mitochondrial state, ATP hydrolysis, [Mg2+]i and [Ca2+]i studied in isolated rat cardiomyocytes.
AuthorsLeyssens A, Nowicky AV, Patterson L, Crompton M, Duchen MR
JournalJ Physiol
PubMed ID8910200
1. As ATP has a higher affinity for Mg2+ than ADP, the cytosolic magnesium concentration rises upon ATP hydrolysis. We have therefore used the Mg(2+)-sensitive fluorescent indicator Magnesium Green (MgG) to provide an index of changing ATP concentration in single rat cardiomyocytes in response to altered mitochondrial state. 2. In ... More
Three distinct mechanisms generate oxygen free radicals in neurons and contribute to cell death during anoxia and reoxygenation.
AuthorsAbramov AY, Scorziello A, Duchen MR
JournalJ Neurosci
PubMed ID17267568
Ischemia is a major cause of brain damage, and patient management is complicated by the paradoxical injury that results from reoxygenation. We have now explored the generation of reactive oxygen species (ROS) in hippocampal and cortical neurons in culture in response to oxygen and glucose deprivation or metabolic inhibition and ... More
GABA uptake into astrocytes is not associated with significant metabolic cost: implications for brain imaging of inhibitory transmission.
AuthorsChatton JY, Pellerin L, Magistretti PJ
JournalProc Natl Acad Sci U S A
PubMed ID14530410
Synaptically released glutamate has been identified as a signal coupling excitatory neuronal activity to increased glucose utilization. The proposed mechanism of this coupling involves glutamate uptake into astrocytes resulting in increased intracellular Na+ (Nai+) and activation of the Na+/K+-ATPase. Increased metabolic demand linked to disruption of Nai+ homeostasis activates glucose ... More
Dependence of transient and residual calcium dynamics on action-potential patterning during neuropeptide secretion.
AuthorsMuschol M, Salzberg BM
JournalJ Neurosci
PubMed ID10995820
Secretion of the neuropeptide arginine vasopressin (AVP) from the neurohypophysis is optimized by short phasic bursts of action potentials with a mean intraburst frequency around 10 Hz. Several hypotheses, most prominently action-potential broadening and buildup of residual calcium, have been proposed to explain this frequency dependence of AVP release. However, ... More
NH-sulfoximine: A novel pharmacological inhibitor of the mitochondrial F1 Fo -ATPase, which suppresses viability of cancerous cells.
Authors
JournalBr J Pharmacol
PubMed ID33037618
GABA is a modulator, rather than a classical transmitter, in the medial nucleus of the trapezoid body-lateral superior olive sound localization circuit.
Authors
JournalJ Physiol
PubMed ID30776090
A painful neuropathy-associated Nav1.7 mutant leads to time-dependent degeneration of small-diameter axons associated with intracellular Ca2+ dysregulation and decrease in ATP levels.
Authors
JournalMol Pain
PubMed ID27821467
Changes in transepithelial electrical resistance and intracellular ion concentration in TGF-β-induced epithelial-mesenchymal transition of retinal pigment epithelial cells.