Spatially organised mitochondrial calcium uptake through a novel pathway in chick neurones.
AuthorsCoatesworth W, Bolsover S
JournalCell Calcium
PubMed ID16338004
'A brief depolarisation of chick sensory neurones evokes a calcium increase in mitochondria that peaks 1-2s after the depolarisation event and then decays over tens of seconds. Peripheral mitochondria take up more calcium than do central ones, even when the cytosolic calcium increase is spatially homogeneous. The calcium influx into ... More
Ion selectivities of the Ca(2+) sensors for exocytosis in rat phaeochromocytoma cells.
AuthorsKishimoto T, Liu TT, Ninomiya Y, Takagi H, Yoshioka T, Ellis-Davies GC, Miyashita Y, Kasai H
JournalJ Physiol
PubMed ID11410622
'1. The ion selectivities of the Ca(2+) sensors for the two components of exocytosis in rat phaeochromocytoma (PC12) cells were examined by measurement of membrane capacitance and amperometry. The cytosolic concentrations of metal ions were increased by photolysis of caged-Ca(2+) compounds and measured with low-affinity indicators benzothiazole coumarin (BTC) or ... More
Early requirement for alpha-SNAP and NSF in the secretory cascade in chromaffin cells.
AuthorsXu T, Ashery U, Burgoyne RD, Neher E
JournalEMBO J
PubMed ID10369670
'NSF and alpha-SNAP have been shown to be required for SNARE complex disassembly and exocytosis. However, the exact requirement for NSF and alpha-SNAP in vesicular traffic through the secretory pathway remains controversial. We performed a study on the kinetics of exocytosis from bovine chromaffin cells using high time resolution capacitance ... More
Roles of Ca2+ and crossbridge kinetics in determining the maximum rates of Ca2+ activation and relaxation in rat and guinea pig skinned trabeculae.
AuthorsPalmer S, Kentish JC
JournalCirc Res
PubMed ID9686757
'We examined the influences of Ca2+ and crossbridge kinetics on the maximum rate of force development during Ca2+ activation of cardiac myofibrils and on the maximum rate of relaxation. Flash photolysis of diazo-2 or nitrophenyl-EGTA was used to produce a sudden decrease or increase, respectively, in [Ca2+] within Triton-skinned trabeculae ... More
Ca2+ entry in CHO cells, after Ca2+ stores depletion, is mediated by arachidonic acid.
AuthorsGailly P
JournalCell Calcium
PubMed ID9883283
'Transfected Chinese hamster ovary cells expressing the rat neurotensin receptor (CHO-NTR cells) were used to study the 'Ca2+ stores depletion-Ca2+ entry' coupling which follows stimulation with neurotensin and liberation of inositol 1,4,5-trisphosphate. This coupling could be dissociated in time: the stores were emptied by stimulation with neurotensin in the absence ... More
cGMP inhibits IP3-induced Ca2+ release in intact rat megakaryocytes via cGMP- and cAMP-dependent protein kinases.
AuthorsTertyshnikova S, Yan X, Fein A
JournalJ Physiol
PubMed ID9729619
'1. Inhibition of inositol 1,4,5-trisphosphate (IP3) receptor-mediated Ca2+ release by cGMP was examined in intact rat megakaryocytes, by using a combination of single cell fluorescence microscopy to monitor intracellular free calcium ([Ca2+]i) and flash photolysis of caged second messengers. 2. Sodium nitroprusside (SNP), a nitric oxide (NO) donor, and the ... More
Activation of trypsinogen in large endocytic vacuoles of pancreatic acinar cells.
'The intracellular activation of trypsinogen, which is both pH- and calcium-dependent, is an important early step in the development of acute pancreatitis. The cellular compartment in which trypsinogen activation occurs currently is unknown. We therefore investigated the site of intracellular trypsinogen activation by using an established cellular model of acute ... More
Local calcium transients regulate the spontaneous motility of dendritic filopodia.
AuthorsLohmann C, Finski A, Bonhoeffer T
JournalNat Neurosci
PubMed ID15711541
'During development, dendrites, and in particular dendritic filopodia, undergo extensive structural remodeling, presumably to help establish synaptic contacts. Here, we investigated the role of calcium signaling in dendritic plasticity by simultaneously recording calcium dynamics and filopodial growth in rat hippocampal slice cultures. Local calcium transients occurred in dendritic filopodia and ... More
Regulation of dynamic behavior of cardiac ryanodine receptor by Mg2+ under simulated physiological conditions.
AuthorsZahradníková A, Dura M, Györke I, Escobar AL, Zahradník I, Györke S
JournalAm J Physiol Cell Physiol
PubMed ID12839831
'Mg2+, an important constituent of the intracellular milieu in cardiac myocytes, is known to inhibit ryanodine receptor (RyR) Ca2+ release channels by competing with Ca2+ at the cytosolic activation sites of the channel. However, the significance of this competition for local, dynamic Ca2+-signaling processes thought to govern cardiac excitation-contraction (EC) ... More
Photolysis-induced suppression of inhibition in rat hippocampal CA1 pyramidal neurons.
AuthorsWang J, Zucker RS
JournalJ Physiol
PubMed ID11410632
'1. Whole cell patch clamp recording, Ca(2+) measurement with ratiometric fluorescent dyes and photolysis of caged Ca(2+) were combined to investigate the depolarization- and photolysis-induced suppression of inhibition (DSI and PSI) in rat hippocampal CA1 pyramidal cells. 2. A 5-s depolarization from -70 mV to 0 mV or a 6-s ... More
Cysteine-disulfide cross-linking to monitor SNARE complex assembly during endoplasmic reticulum-Golgi transport.
AuthorsFlanagan JJ, Barlowe C
JournalJ Biol Chem
PubMed ID16303754
'Assembly of cognate SNARE proteins into SNARE complexes is required for many intracellular membrane fusion reactions. However, the mechanisms that govern SNARE complex assembly and disassembly during fusion are not well understood. We have devised a new in vitro cross-linking assay to monitor SNARE complex assembly during fusion of endoplasmic ... More
Protein kinase A-dependent and -independent stimulation of exocytosis by cAMP in mouse pancreatic B-cells.
AuthorsRenström E, Eliasson L, Rorsman P
JournalJ Physiol
PubMed ID9234200
'1. The mechanisms by which cAMP stimulates Ca(2+)-dependent insulin secretion were investigated by combining measurements of whole-cell Ca2+ currents, the cytoplasmic free Ca2+ concentration ([Ca2+]i) and membrane capacitance in single mouse B-cells maintained in tissue culture. 2. Cyclic AMP stimulated exocytosis > 4-fold in whole-cell experiments in which secretion was ... More
In vivo two-photon laser-scanning microscopy of Ca2+ dynamics in visual motion-sensitive neurons.
AuthorsKalb J, Nielsen T, Fricke M, Egelhaaf M, Kurtz R
JournalBiochem Biophys Res Commun
PubMed ID15020223
'We applied two-photon laser-scanning microscopy (TPLSM) to motion-sensitive visual interneurons of the fly to study Ca(2+) dynamics in vivo at a higher spatial and temporal resolution than possible with conventional fluorescence microscopy. Based on a custom-built two-photon microscope, we performed line scans to measure changes in presynaptic Ca(2+) concentrations elicited ... More
Cyclic ADP-ribose-gated Ca2+ release in sea urchin eggs requires an elevated.
AuthorsGuo X, Becker PL
JournalJ Biol Chem
PubMed ID9202011
'Cyclic ADP-ribose (cADPr) has been shown to release intracellular Ca2+ from sea urchin eggs and a variety of vertebrate cell types, although its mechanism of action remains elusive. We employed the caged version of cADPr to study the [Ca2+] transient kinetics in intact sea urchin eggs for insights into how ... More
Purinergic control of intercellular communication between Hensen's cells of the guinea-pig cochlea.
AuthorsLagostena L, Ashmore JF, Kachar B, Mammano F
JournalJ Physiol
PubMed ID11251051
'1. Hensen''s cells in the isolated cochlea were stimulated by extracellular adenosine 5''-triphosphate (ATP) applied to their endolymphatic surface while changes in membrane current and intracellular calcium concentration ([Ca2+]i) were measured simultaneously. The response consisted of (i) an initial rapid inward current accompanied by elevation of the [Ca2+]i, (ii) a ... More
Frequency detection and temporally dispersed synaptic signal association through a metabotropic glutamate receptor pathway.
AuthorsBatchelor AM, Garthwaite J
JournalNature
PubMed ID8985249
'In the classical view, a central neuron integrates incoming synaptic information by simple algebraic summation of the resultant bioelectrical signals that coincide in time. The voltage dependence of the NMDA (N-methyl-D-aspartate) type of ionotropic glutamate receptor endows neurons with an additional tool that allows one synaptic input to influence another, ... More
P2Y purinoceptors inhibit exocytosis in adrenal chromaffin cells via modulation of voltage-operated calcium channels.
AuthorsPowell AD, Teschemacher AG, Seward EP
JournalJ Neurosci
PubMed ID10632590
'We have used combined membrane capacitance measurements (C(m)) and voltage-clamp recordings to examine the mechanisms underlying modulation of stimulus-secretion coupling by a G(i/o)-coupled purinoceptor (P2Y) in adrenal chromaffin cells. P2Y purinoceptors respond to extracellular ATP and are thought to provide an important inhibitory feedback regulation of catecholamine release from central ... More
Role of Ca2+ in determining the rate of tension development and relaxation in rat skinned myocardium.
AuthorsSaeki Y, Kobayashi T, Yasuda S, Nishimura S, Sugiura S, Yamashita H, Sugi H
JournalJ Mol Cell Cardiol
PubMed ID15010276
'To clarify the roles of Ca2+ and crossbridge kinetics in determining the cardiac contraction profile, we analyzed the rate of tension development following nitrophenyl-EGTA photolysis and the rate of relaxation following diazo-2 photolysis in the absence and presence of phosphate (Pi, 5 mM) in rat skinned ventricular trabeculae. The rate ... More
Time-resolved X-ray diffraction by skinned skeletal muscle fibers during activation and shortening.
'Force, sarcomere length, and equatorial x-ray reflections (using synchrotron radiation) were studied in chemically skinned bundles of fibers from Rana temporaria sartorius muscle, activated by UV flash photolysis of a new photolabile calcium chelator, NP-EGTA. Experiments were performed with or without compression by 3% dextran at 4 degrees C. Isometric ... More
Distribution of Ca2+ extrusion sites on the mouse pancreatic acinar cell surface.
AuthorsBelan P, Gerasimenko O, Petersen OH, Tepikin AV
JournalCell Calcium
PubMed ID9232347
'The localizations of Ca2+ extrusion sites in mouse pancreatic acinar cells during elevation of the intracellular free calcium concentration ([Ca2+]i) have been studied. During an agonist stimulated calcium elevation as well as when intracellular calcium is released from a ''caged compound'', Ca2+ is primarily extruded from the apical secretory pole ... More
Inhibition of SNARE complex assembly differentially affects kinetic components of exocytosis.
AuthorsXu T, Rammner B, Margittai M, Artalejo AR, Neher E, Jahn R
JournalCell
PubMed ID10619425
'In chromaffin cells, an increase in intracellular Ca2+ leads to an exocytotic burst followed by sustained secretion. The burst can be further resolved into two kinetically distinct components, which suggests the presence of two separate pools of vesicles. To investigate how these components relate to SNARE complex formation, we introduced ... More
Contribution of a calcium-activated non-specific conductance to NMDA receptor-mediated synaptic potentials in granule cells of the frog olfactory bulb.
AuthorsHall BJ, Delaney KR
JournalJ Physiol
PubMed ID12231641
'We studied granule cells (GCs) in the intact frog olfactory bulb (OB) by combining whole-cell recordings and functional two-photon Ca(2+) imaging in an in vitro nose-brain preparation. GCs are local interneurones that shape OB output via distributed dendrodendritic inhibition of OB projection neurones, the mitral-tufted cells (MTCs). In contrast to ... More
Two-photon activation of caged calcium with submicron, submillisecond resolution.
AuthorsBrown EB, Webb WW
JournalMethods Enzymol
PubMed ID9661159
Intercellular calcium signaling and flash photolysis of caged compounds. A sensitive method to evaluate gap junctional coupling.
AuthorsLeybaert L, Sanderson MJ
JournalMethods Mol Biol
PubMed ID11218662
Neurobiology with caged calcium.
AuthorsEllis-Davies GC,
JournalChem Rev
PubMed ID18447376
In this review, I give a brief outline of the wide variety of cells and cellular functions regulated by Ca2+. Using this basic biological context, I tell the history of the development of caged Ca2+ molecules from the perspective of the requirements of the experimental application of each photosensitive probe, ... More
The endoplasmic reticulum: one continuous or several separate Ca(2+) stores?
AuthorsPetersen OH, Tepikin A, Park MK
JournalTrends Neurosci
PubMed ID11311379
The Ca2+ store and sink in the endoplasmic reticulum (ER) is important for Ca2+ signal integration and for conveyance of information in spatial and temporal domains. Textbooks regard the ER as one continuous network, but biochemical and biophysical studies revealed apparently discrete ER Ca2+ stores. Recent direct studies of ER ... More
Caged compounds: photorelease technology for control of cellular chemistry and physiology.
AuthorsEllis-Davies GC
JournalNat Methods
PubMed ID17664946
Caged compounds are light-sensitive probes that functionally encapsulate biomolecules in an inactive form. Irradiation liberates the trapped molecule, permitting targeted perturbation of a biological process. Uncaging technology and fluorescence microscopy are 'optically orthogonal': the former allows control, and the latter, observation of cellular function. Used in conjunction with other technologies ... More
Calcium buffering capacity of neuronal cell cytosol measured by flash photolysis of calcium buffer NP-EGTA.
AuthorsFleet A, Ellis-Davies G, Bolsover S
JournalBiochem Biophys Res Commun
PubMed ID9784424
N1E-115 mouse neuroblastoma cells were injected with a calcium buffer/indicator solution to allow both ratiometric measurement of free calcium concentration and the release of calcium ions upon UV flash. The solution contained sulforhodamine, a marker dye used to estimate the volume injected; fluo-3, a calcium indicator, and NP-EGTA, a high ... More
Caged compounds: tools for illuminating neuronal responses and connections.
AuthorsNerbonne JM
JournalCurr Opin Neurobiol
PubMed ID8794086
A number of new 'caged' intracellular second messengers and neurotransmitters have been developed using the photolabile o-nitrobenzyl group. This chemistry has also recently been exploited in novel ways, including the development of caged enzyme substrates and caged proteins. Although caged compounds continue to be used primarily for mechanistic (kinetic) studies ... More
Development and application of caged calcium.
AuthorsEllis-Davies GC
JournalMethods Enzymol
PubMed ID12622152
Several caged calciums have been synthesized since 1986, and three are commercially available: DM-nitrophen, NP-EGTA, and nitr-5. Each of these caged compounds has uniquely useful properties, making the choice of which cage to use dependent on the specific experiment (i.e., the cell type and divalent cation requirements of the experiments ... More
Motility of myosin V regulated by the dissociation of single calmodulin.
AuthorsNguyen H, Higuchi H
JournalNat Struct Mol Biol
PubMed ID15665867
Myosin V is a calmodulin-binding motor protein. The dissociation of single calmodulin molecules from individual myosin V molecules at 1 microM Ca(2+) correlates with a reduction in sliding velocity in an in vitro motility assay. The dissociation of two calmodulin molecules at 5 microM Ca(2+) correlates with a detachment of ... More
Rapid adaptation of cardiac ryanodine receptors: modulation by Mg2+ and phosphorylation.
Channel adaptation is a fundamental feature of sarcoplasmic reticulum calcium release channels (called ryanodine receptors, RyRs). It permits successive increases in the intracellular concentration of calcium (Ca2+) to repeatedly but transiently activate channels. Adaptation of RyRs in the absence of magnesium (Mg2+) and adenosine triphosphate is an extremely slow process ... More
Visualization of stochastic Ca2+ signals in the formed somites during the early segmentation period in intact, normally developing zebrafish embryos.
AuthorsLeung CF, Miller AL, Korzh V, Chong SW, Sleptsova-Freidrich I, Webb SE,
JournalDev Growth Differ
PubMed ID19712266
Localized Ca(2+) signals were consistently visualized in the formed somites of intact zebrafish embryos during the early segmentation period. Unlike the regular process of somitogenesis, these signals were stochastic in nature with respect to time and location. They did, however, occur predominantly at the medial and lateral boundaries within the ... More
Analysis of neurotransmitter release mechanisms by photolysis of caged Ca²? in an autaptic neuron culture system.
AuthorsBurgalossi A, Jung S, Man KN, Nair R, Jockusch WJ, Wojcik SM, Brose N, Rhee JS,
JournalNat Protoc
PubMed ID22722370
Neurotransmitter release is triggered by membrane depolarization, Ca(2+) influx and Ca(2+) sensing by the release machinery, causing synaptic vesicle (SV) fusion with the plasma membrane. Interlinked is a complex membrane cycle in which vesicles are tethered to the release site, primed, fused and recycled. As many of these processes are ... More
Continuous vesicle cycling in the synaptic terminal of retinal bipolar cells.
AuthorsLagnado L, Gomis A, Job C
JournalNeuron
PubMed ID8938127
Endocytosis and exocytosis were investigated in the synaptic terminal of retinal bipolar cells by monitoring the uptake and loss of the fluorescent dye FM1-43. Depolarization in the presence of Ca2+ stimulated a continuous cycle of exocytosis and endocytosis that was approximately balanced at rates up to 3800 vesicles per s. ... More
PINK1-associated Parkinson's disease is caused by neuronal vulnerability to calcium-induced cell death.
AuthorsGandhi S, Wood-Kaczmar A, Yao Z, Plun-Favreau H, Deas E, Klupsch K, Downward J, Latchman DS, Tabrizi SJ, Wood NW, Duchen MR, Abramov AY,
JournalMol Cell
PubMed ID19285945
Mutations in PINK1 cause autosomal recessive Parkinson's disease. PINK1 is a mitochondrial kinase of unknown function. We investigated calcium homeostasis and mitochondrial function in PINK1-deficient mammalian neurons. We demonstrate physiologically that PINK1 regulates calcium efflux from the mitochondria via the mitochondrial Na(+)/Ca(2+) exchanger. PINK1 deficiency causes mitochondrial accumulation of calcium, ... More
Munc18-1 promotes large dense-core vesicle docking.
AuthorsVoets T, Toonen RF, Brian EC, de Wit H, Moser T, Rettig J, Südhof TC, Neher E, Verhage M
JournalNeuron
PubMed ID11545717
Secretory vesicles dock at the plasma membrane before Ca(2+) triggers their exocytosis. Exocytosis requires the assembly of SNARE complexes formed by the vesicle protein Synaptobrevin and the membrane proteins Syntaxin-1 and SNAP-25. We analyzed the role of Munc18-1, a cytosolic binding partner of Syntaxin-1, in large dense-core vesicle (LDCV) secretion. ... More
An anaphase calcium signal controls chromosome disjunction in early sea urchin embryos.
AuthorsGroigno L, Whitaker M
JournalCell
PubMed ID9458044
A transient increase in intracellular calcium concentration [Ca2+]i occurs throughout the cell as sea urchin embryos enter anaphase of the first cell cycle. The transient just precedes chromatid disjunction and spindle elongation. Microinjection of calcium chelators or heparin, an InsP3 receptor antagonist, blocks chromosome separation. Photorelease of calcium or InsP3 ... More
Confocal imaging and local photolysis of caged compounds: dual probes of synaptic function.
AuthorsWang SS, Augustine GJ
JournalNeuron
PubMed ID7576625
Chemical signals generated at synapses are highly limited in both spatial range and time course, so that experiments studying such signals must measure and manipulate them in both these dimensions. We describe an optical system that combines confocal laser scanning microscopy, to measure such signals, with focal photolysis of caged ... More
Intracellular calcium dependence of large dense-core vesicle exocytosis in the absence of synaptotagmin I.
AuthorsVoets T, Moser T, Lund PE, Chow RH, Geppert M, Südhof TC, Neher E
JournalProc Natl Acad Sci U S A
PubMed ID11562488
Synaptotagmin I is a synaptic vesicle-associated protein essential for synchronous neurotransmission. We investigated its impact on the intracellular Ca(2+)-dependence of large dense-core vesicle (LDCV) exocytosis by combining Ca(2+)-uncaging and membrane capacitance measurements in adrenal slices from mouse synaptotagmin I null mutants. Synaptotagmin I-deficient chromaffin cells displayed prolonged exocytic delays and ... More
Morphological constraints on calcium dependent glutamate receptor trafficking into individual dendritic spine.
AuthorsKorkotian E, Segal M
JournalCell Calcium
PubMed ID17187855
Glutamate receptor trafficking into dendritic spines is a pivotal step in synaptic plasticity, yet the relevance of plasticity-producing rise of [Ca2+]i and of spine morphology to subsequent delivery of glutamate receptors into dendritic spine heads are still not well understood. Following chemical induction of LTP, an increase in eGFP-GluR1 fluorescence ... More
Sensitization of regulated exocytosis by protein kinase C.
AuthorsZhu H, Hille B, Xu T
JournalProc Natl Acad Sci U S A
PubMed ID12486252
Activation of protein kinase C (PKC) increases vesicular secretion in many cell types. We determined the calcium dependence of secretion and the size of the readily releasable pool of secretory granules in pituitary gonadotropes by photorelease of caged-calcium. The calcium affinity for exocytosis was roughly doubled by activation of PKC ... More
Nerve growth factor-induced differentiation changes the cellular organization of regulated Peptide release by PC12 cells.
AuthorsNg YK, Lu X, Watkins SC, Ellis-Davies GC, Levitan ES
JournalJ Neurosci
PubMed ID12019308
PC12 cells, like endocrine chromaffin cells, undergo neuronal-like differentiation in response to nerve growth factor (NGF). Here we report that this phenotype conversion produces major changes in release of a green fluorescent protein-tagged neuropeptide-hormone. First, the spatial distribution of the releasable pool is altered; peptide release from untreated cells is ... More
Involvement of the cytoskeleton in Junin virus multiplication.
AuthorsCandurra NA, Lago MJ, Maskin L, Damonte EB
JournalJ Gen Virol
PubMed ID9934697
The role of the cellular cytoskeleton in Junin virus (JV) infection was explored in two ways. Firstly, the action of inhibitors that affect individual cytoskeletal systems (microtubules or microfilaments) selectively was analysed. It was found that perturbations of microtubule or microfilament networks caused by colchicine, nocodazole, nifedipine, EGTA or DMSO ... More
Flash photolysis using a light emitting diode: an efficient, compact, and affordable solution.
AuthorsBernardinelli Y, Haeberli C, Chatton JY
JournalCell Calcium
PubMed ID15862347
Flash photolysis has become an essential technique for dynamic investigations of living cells and tissues. This approach offers several advantages for instantly changing the concentration of bioactive compounds outside and inside living cells with high spatial resolution. Light sources for photolysis need to deliver pulses of high intensity light in ... More
Nitrophenyl-EGTA, a photolabile chelator that selectively binds Ca2+ with high affinity and releases it rapidly upon photolysis.
AuthorsEllis-Davies GC, Kaplan JH
JournalProc Natl Acad Sci U S A
PubMed ID8278362
The synthesis and properties of a caged calcium are described. The compound is an ortho-nitrophenyl derivative of EGTA. It is synthesized in 10 steps and with 24% overall yield. The photosensitive chelator, nitrophenyl-EGTA, has a Kd value for Ca2+ of 80 nM and for Mg2+ of 9 mM. Upon exposure ... More
Transmitter-evoked local calcium release stabilizes developing dendrites.
AuthorsLohmann C, Myhr KL, Wong RO
JournalNature
PubMed ID12110889
In the central nervous system, dendritic arborizations of neurons undergo dynamic structural remodelling during development. Processes are elaborated, maintained or eliminated to attain the adult pattern of synaptic connections. Although neuronal activity influences this remodelling, it is not known how activity exerts its effects. Here we show that neurotransmission-evoked calcium ... More
Laser photolysis of caged calcium: rates of calcium release by nitrophenyl-EGTA and DM-nitrophen.
AuthorsEllis-Davies GC, Kaplan JH, Barsotti RJ
JournalBiophys J
PubMed ID8789118
Nitrophenyl-EGTA and DM-nitrophen are Ca2+ cages that release Ca2+ when cleaved upon illumination with near-ultraviolet light. Laser photolysis of nitrophenyl-EGTA produced transient intermediates that decayed biexponentially with rates of 500,000 s-1 and 100,000 s-1 in the presence of saturating Ca2+ and 290,000 s-1 and 68,000 s-1 in the absence of ... More
Multiple exocytotic pathways in pancreatic beta cells.
AuthorsTakahashi N, Kadowaki T, Yazaki Y, Miyashita Y, Kasai H
JournalJ Cell Biol
PubMed ID9214381
Ca2+-dependent exocytotic pathways in mouse pancreatic beta cells were investigated using both capacitance measurement and amperometric detection of vesicular contents. Serotonin was preloaded into large dense-core vesicles for the amperometry. Exocytosis was induced by rapid elevation of cytosolic Ca2+ concentrations using caged-Ca2+ compounds. Capacitance measurement revealed two major components of ... More
Inositol 1,4,5-trisphosphate directs Ca(2+) flow between mitochondria and the Endoplasmic/Sarcoplasmic reticulum: a role in regulating cardiac autonomic Ca(2+) spiking.
AuthorsJaconi M, Bony C, Richards SM, Terzic A, Arnaudeau S, Vassort G, Pucéat M
JournalMol Biol Cell
PubMed ID10793156
The signaling role of the Ca(2+) releaser inositol 1,4, 5-trisphosphate (IP(3)) has been associated with diverse cell functions. Yet, the physiological significance of IP(3) in tissues that feature a ryanodine-sensitive sarcoplasmic reticulum has remained elusive. IP(3) generated by photolysis of caged IP(3) or by purinergic activation of phospholipase Cgamma slowed ... More
Induction of filopodia by direct local elevation of intracellular calcium ion concentration.
AuthorsLau PM, Zucker RS, Bentley D
JournalJ Cell Biol
PubMed ID10366598
In neuronal growth cones, cycles of filopodial protrusion and retraction are important in growth cone translocation and steering. Alteration in intracellular calcium ion concentration has been shown by several indirect methods to be critically involved in the regulation of filopodial activity. Here, we investigate whether direct elevation of [Ca2+]i, which ... More
Spatial control of Ca2+ signaling by nicotinic acid adenine dinucleotide phosphate diffusion and gradients.
AuthorsChurchill GC, Galione A
JournalJ Biol Chem
PubMed ID11006280
Intracellular Ca(2+) is able to control numerous cellular responses through complex spatiotemporal organization. Ca(2+) waves mediated by inositol trisphosphate or ryanodine receptors propagate by Ca(2+)-induced Ca(2+) release and therefore do not have an absolute requirement for a gradient in either inositol trisphosphate or cyclic ADP-ribose, respectively. In contrast, we report ... More
Photolysis of caged calcium in femtoliter volumes using two-photon excitation.
A new technique for the determination of the two-photon uncaging action cross section (deltau) of photolyzable calcium cages is described. This technique is potentially applicable to other caged species that can be chelated by a fluorescent indicator dye, as well as caged fluorescent compounds. The two-photon action cross sections of ... More
High mechanical efficiency of the cross-bridge powerstroke in skeletal muscle.
AuthorsSugi H, Iwamoto H, Akimoto T, Kishi H
JournalJ Exp Biol
PubMed ID12604580
We were interested to estimate the maximum mechanical efficiency with which chemical energy derived from ATP hydrolysis is converted into mechanical work by individual cross-bridges when they perform their powerstroke synchronously. Glycerinated rabbit psoas muscle fibres, containing ATP molecules almost equal in number to the cross-bridges within the fibre, were ... More
Identification of a ryanodine receptor in rat heart mitochondria.
AuthorsBeutner G, Sharma VK, Giovannucci DR, Yule DI, Sheu SS
JournalJ Biol Chem
PubMed ID11297554
Recent studies have shown that, in a wide variety of cells, mitochondria respond dynamically to physiological changes in cytosolic Ca(2+) concentrations ([Ca(2+)](c)). Mitochondrial Ca(2+) uptake occurs via a ruthenium red-sensitive calcium uniporter and a rapid mode of Ca(2+) uptake. Surprisingly, the molecular identity of these Ca(2+) transport proteins is still ... More
Fusion pore expansion is a slow, discontinuous, and Ca2+-dependent process regulating secretion from alveolar type II cells.
AuthorsHaller T, Dietl P, Pfaller K, Frick M, Mair N, Paulmichl M, Hess MW, Furst J, Maly K
JournalJ Cell Biol
PubMed ID11604423
In alveolar type II cells, the release of surfactant is considerably delayed after the formation of exocytotic fusion pores, suggesting that content dispersal may be limited by fusion pore diameter and subject to regulation at a postfusion level. To address this issue, we used confocal FRAP and N-(3-triethylammoniumpropyl)-4-(4-[dibutylamino]styryl) pyridinium dibromide ... More
Local perinuclear calcium signals associated with mitosis-entry in early sea urchin embryos.
AuthorsWilding M, Wright EM, Patel R, Ellis-Davies G, Whitaker M
JournalJ Cell Biol
PubMed ID8858173
Using calcium-sensitive dyes together with their dextran conjugates and confocal microscopy, we have looked for evidence of localized calcium signaling in the region of the nucleus before entry into mitosis, using the sea urchin egg first mitotic cell cycle as a model. Global calcium transients that appear to originate from ... More
Local uncaging of caged Ca(2+) reveals distribution of Ca(2+)-activated Cl(-) channels in pancreatic acinar cells.
AuthorsPark MK, Lomax RB, Tepikin AV, Petersen OH
JournalProc Natl Acad Sci U S A
PubMed ID11535807
In exocrine acinar cells, Ca(2+)-activated Cl(-) channels in the apical membrane are essential for fluid secretion, but it is unclear whether such channels are important for Cl(-) uptake at the base. Whole-cell current recording, combined with local uncaging of caged Ca(2+), was used to reveal the Cl(-) channel distribution in ... More
Influence of ionic strength on the actomyosin reaction steps in contracting skeletal muscle fibers.
AuthorsIwamoto H
JournalBiophys J
PubMed ID10827990
Muscle contraction occurs as the result of actin-myosin interaction, which is mediated by the intermolecular forces exerted at the actin-myosin interface. To obtain information about the nature of these intermolecular forces, we tested the sensitivity of various contractile parameters of skinned skeletal muscle fibers to ionic strength (IS) at 3-5 ... More
Dynamic regulation of spine-dendrite coupling in cultured hippocampal neurons.
AuthorsKorkotian E, Holcman D, Segal M
JournalEur J Neurosci
PubMed ID15548208
We investigated the role of dendritic spine morphology in spine-dendrite calcium communication using novel experimental and theoretical approaches. A transient rise in [Ca2+]i was produced in individual spine heads of Fluo-4-loaded cultured hippocampal neurons by flash photolysis of caged calcium. Following flash photolysis in the spine head, a delayed [Ca2+]i ... More
The intraacrosomal calcium pool plays a direct role in acrosomal exocytosis.
AuthorsDe Blas G, Michaut M, Treviño CL, Tomes CN, Yunes R, Darszon A, Mayorga LS
JournalJ Biol Chem
PubMed ID12379648
The acrosome reaction is a unique type of regulated exocytosis. The single secretory granule of the sperm fuses at multiple points with the overlying plasma membrane. In the past few years we have characterized several aspects of this process using streptolysin O-permeabilized human spermatozoa. Here we show that Rab3A triggers ... More
Ca2+ signalling and membrane current activated by cADPr in starfish oocytes.
AuthorsMoccia F, Nusco GA, Lim D, Ercolano E, Gragnaniello G, Brown ER, Santella L
JournalPflugers Arch
PubMed ID12756567
Cyclic ADP-ribose (cADPr) is a second messenger that regulates intracellular free [Ca2+] ([Ca2+](i)) in a variety of cell types, including immature oocytes from the starfish Astropecten auranciacus. In this study, we employed confocal laser scanning microscopy and voltage clamp techniques to investigate the source of the cADPr-elicited Ca2+ wave originating ... More
The regulatory light chains of myosin modulate cross-bridge cycling in skeletal muscle.
AuthorsSzczesna D, Zhao J, Potter JD
JournalJ Biol Chem
PubMed ID8617809
We investigated the kinetics of Ca2+ activation of skeletal muscle contraction elicited by the photolysis of caged Ca2+. Previously we showed that partial extraction of the 18-kDa regulatory light chains (RLCs) of myosin decreased the rate of force development and was subsequently increased by approximately 20% following reconstitution with RLCs ... More
Ca2+-controlled competitive diacylglycerol binding of protein kinase C isoenzymes in living cells.
AuthorsLenz JC, Reusch HP, Albrecht N, Schultz G, Schaefer M
JournalJ Cell Biol
PubMed ID12391024
The cellular decoding of receptor-induced signaling is based in part on the spatiotemporal activation pattern of PKC isoforms. Because classical and novel PKC isoforms contain diacylglycerol (DAG)-binding C1 domains, they may compete for DAG binding. We reasoned that a Ca2+-induced membrane association of classical PKCs may accelerate the DAG binding ... More
The SNARE protein SNAP-25 is linked to fast calcium triggering of exocytosis.
AuthorsSørensen JB, Matti U, Wei SH, Nehring RB, Voets T, Ashery U, Binz T, Neher E, Rettig J
JournalProc Natl Acad Sci U S A
PubMed ID11830673
Synchronous neurotransmission depends on the tight coupling between Ca(2+) influx and fusion of neurotransmitter-filled vesicles with the plasma membrane. The vesicular soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein synaptobrevin 2 and the plasma membrane SNAREs syntaxin 1 and synaptosomal protein of 25 kDa (SNAP-25) are essential for calcium-triggered exocytosis. ... More
Endocytosis of secretory granules in mouse pancreatic beta-cells evoked by transient elevation of cytosolic calcium.
AuthorsEliasson L, Proks P, Ammälä C, Ashcroft FM, Bokvist K, Renström E, Rorsman P, Smith PA
JournalJ Physiol
PubMed ID8799897
1. To investigate the mechanisms regulating the reuptake of secretory granule membranes following regulated exocytosis, we have monitored changes in cell capacitance in single pancreatic beta-cells. 2. Membrane retrieval (endocytosis) occurred both in a continuous manner and in abrupt steps, corresponding to the simultaneous retrieval of 50-100 granules. The large ... More
Rapid coupling of calcium release to depolarization in Limulus polyphemus ventral photoreceptors as revealed by microphotolysis and confocal microscopy.
AuthorsUkhanov K, Payne R
JournalJ Neurosci
PubMed ID9030629
Microphotolysis and confocal microscopy were used to investigate the timing of calcium release and of the electrical response in Limulus polyphemus ventral photoreceptors. The fluorescent dyes Fluo-3 and Calcium Green-5N were used to monitor local Ca2+ elevations. Photolysis of caged inositol trisphosphate (InsP3) close to the plasma membrane of the ... More
Millisecond studies of calcium-dependent exocytosis in pituitary melanotrophs: comparison of the photolabile calcium chelators nitrophenyl-EGTA and DM-nitrophen.
AuthorsParsons TD, Ellis-Davies GC, Almers W
JournalCell Calcium
PubMed ID8732258
DM-nitrophen (DMN) is a photolabile calcium chelator that has been used extensively to study calcium-triggered exocytosis. Nitrophenyl-EGTA (NPE) is a recently synthesized photolabile calcium chelator that, unlike DMN, selectively binds calcium over magnesium. Here, we compare NPE and DMN for their effectiveness in raising cytosolic calcium ([Ca]i) to trigger exocytosis. ... More
Endocytosis in identified rat corticotrophs.
AuthorsLee AK, Tse A
JournalJ Physiol
PubMed ID11389200
1. We used the patch-clamp technique, in conjunction with membrane capacitance measurement, fluorescence measurement of intracellular calcium concentration ([Ca(2+)](i)), and flash photolysis of caged Ca(2+) to study exo- and endocytosis in identified rat corticotrophs. 2. Exocytosis stimulated by depolarization pulses was typically followed by a 'slow' endocytosis that retrieved the ... More
A new caged Ca2+, azid-1, is far more photosensitive than nitrobenzyl-based chelators.
AuthorsAdams SR, Lev-Ram V, Tsien RY
JournalChem Biol
PubMed ID9384535
BACKGROUND: Photolabile chelators that release Ca2+ upon illumination have been used extensively to dissect the role of this important second messenger in cellular processes such as muscle contraction and synaptic transmission. The caged calcium chelators that are presently available are often limited by their inadequate changes in Ca2+ affinity, selectivity ... More
Presynaptic target of Ca2+ action on neuropeptide and acetylcholine release in Aplysia californica.
1. When buccal neuron B2 of Aplysia californica is co-cultured with sensory neurons (SNs), slow peptidergic synapses are formed. When B2 is co-cultured with neurons B3 or B6, fast cholinergic synapses are formed. 2. Patch pipettes were used to voltage clamp pre- and postsynaptic neurons and to load the caged ... More
Kinetics of prephosphorylation reactions and myosin light chain phosphorylation in smooth muscle. Flash photolysis studies with caged calcium and caged ATP.
AuthorsZimmermann B, Somlyo AV, Ellis-Davies GC, Kaplan JH, Somlyo AP
JournalJ Biol Chem
PubMed ID7592592
The pre-myosin light chain (MLC20) phosphorylation components of the lag phase (td) of contractile activation were determined in permeabilized smooth muscles activated by photolytic release of ATP from caged ATP and/or Ca2+ from 4-(2-nitrophenyl)-EGTA (NP-EGTA). Calmodulin (CaM) shortened the td (470 ms at 0 added CaM) that followed Ca2+ release, ... More
Phosphate release and force generation in cardiac myocytes investigated with caged phosphate and caged calcium.
AuthorsAraujo A, Walker JW
JournalBiophys J
PubMed ID9172755
The phosphate (P(i)) dissociation step of the cross-bridge cycle was investigated in skinned rat ventricular myocytes to examine its role in force generation and Ca(2+) regulation in cardiac muscle. Pulse photolysis of caged P(i) (alpha-carboxyl-2-nitrobenzyl phosphate) produced up to 3 mM P(i) within the filament lattice, resulting in an approximately ... More
Fast exocytosis with few Ca(2+) channels in insulin-secreting mouse pancreatic B cells.
AuthorsBarg S, Ma X, Eliasson L, Galvanovskis J, Göpel SO, Obermüller S, Platzer J, Renström E, Trus M, Atlas D, Striessnig J, Rorsman P
JournalBiophys J
PubMed ID11720994
The association of L-type Ca(2+) channels to the secretory granules and its functional significance to secretion was investigated in mouse pancreatic B cells. Nonstationary fluctuation analysis showed that the B cell is equipped with <500 alpha1(C) L-type Ca(2+) channels, corresponding to a Ca(2+) channel density of 0.9 channels per microm(2). ... More
Rapid ATP-dependent priming of secretory granules precedes Ca(2+)-induced exocytosis in mouse pancreatic B-cells.
AuthorsEliasson L, Renström E, Ding WG, Proks P, Rorsman P
JournalJ Physiol
PubMed ID9306281
1. The glucose and ATP dependence of exocytosis were investigated in single mouse pancreatic B-cells by monitoring changes in cell capacitance evoked by voltage-clamp depolarizations, infusion of high [Ca2+]i buffers or photorelease of caged Ca2+ or ATP. 2. In intact B-cells, using the perforated patch whole-cell technique, glucose (5 mM) ... More
ATPase kinetics on activation of rabbit and frog permeabilized isometric muscle fibres: a real time phosphate assay.
AuthorsHe ZH, Chillingworth RK, Brune M, Corrie JE, Trentham DR, Webb MR, Ferenczi MA
JournalJ Physiol
PubMed ID9174999
1. The rate of appearance of inorganic phosphate (Pi) and hence the ATPase activity of rabbit psoas muscle in single permeabilized muscle fibres initially in rigor was measured following laser flash photolysis of the P3-1-(2-nitrophenyl)ethyl ester of ATP (NPE-caged ATP) in the presence and absence of Ca2+. Pi appearance was ... More
Calcium homeostatic mechanisms operating in cultured postnatal rat hippocampal neurones following flash photolysis of nitrophenyl-EGTA.
AuthorsSidky AO, Baimbridge KG
JournalJ Physiol
PubMed ID9401966
1. We examined Ca2+ homeostatic mechanisms in cultured postnatal rat hippocampal neurones by monitoring the recovery of background-subtracted fluo-3 fluorescence levels at 20-22 degrees C immediately following a rapid increase in Ca2+ levels induced by flash photolysis of the caged Ca2+ compound nitrophenyl-EGTA (NP-EGTA). 2. A variety of methods or ... More
alpha-adrenergic stimulation of cytosolic Ca2+ oscillations and exocytosis in identified rat corticotrophs.
AuthorsTse A, Tse FW
JournalJ Physiol
PubMed ID9763629
1. The patch clamp technique was used in conjunction with a fluorescent Ca2+ indicator (indo-1, or indo-1FF) to measure simultaneously cytosolic Ca2+ concentration ([Ca2+]i), ionic current and changes in membrane capacitance in single rat corticotrophs identified with the reverse haemolytic plaque assay. 2. Application of the adrenocorticotropin (ACTH) secretagogue noradrenaline ... More
Properties of exocytotic response in vertebrate photoreceptors.
AuthorsKreft M, Krizaj D, Grilc S, Zorec R
JournalJ Neurophysiol
PubMed ID12660355
Synaptic transmission at the photoreceptor synapse is characterized by continuous release of glutamate in darkness. Release is regulated by the intracellular calcium concentration ([Ca2+]i). We here examined the physiological properties of exocytosis in tiger salamander (Ambystoma tigrinum) retinal rods and cones. Patch-clamp capacitance measurements were used to monitor exocytosis elicited ... More
Inositol-trisphosphate-dependent intercellular calcium signaling in and between astrocytes and endothelial cells.
AuthorsLeybaert L, Paemeleire K, Strahonja A, Sanderson MJ
JournalGlia
PubMed ID9814820
Interactions between astrocytes and endothelial cells are believed to play an important role in the control of blood-brain barrier permeability and transport. Astrocytes and endothelial cells respond to a variety of stimuli with an increase of intracellular free calcium ([Ca2+]i) that is propagated to adjacent cells as an intercellular Ca2+ ... More
Calcium elevation in astrocytes causes an NMDA receptor-dependent increase in the frequency of miniature synaptic currents in cultured hippocampal neurons.
AuthorsAraque A, Sanzgiri RP, Parpura V, Haydon PG
JournalJ Neurosci
PubMed ID9712653
Astrocytes exhibit a form of excitability and communication on the basis of intracellular Ca2+ variations (Cornell-Bell et al., 1990; Charles et al., 1991) that can be initiated by neuronal activity (Dani et al., 1992; Porter and McCarthy, 1996). A Ca2+ elevation in astrocytes induces the release of glutamate (Parpura et ... More
Two components of exocytosis and endocytosis in phaeochromocytoma cells studied using caged Ca2+ compounds.
AuthorsKasai H, Takagi H, Ninomiya Y, Kishimoto T, Ito K, Yoshida A, Yoshioka T, Miyashita Y
JournalJ Physiol
PubMed ID8814606
1. Changes in membrane capacitance evoked by the rapid photolysis of a caged Ca2+ compound, DM-nitrophen or nitrophenyl-EGTA, were investigated in undifferentiated PC12 cells. They were interpreted as representing exocytosis and endocytosis. 2. The Ca2+ jumps evoked two components of exocytosis. Slow exocytosis was selectively evoked with small increases in ... More
Activation kinetics of skinned cardiac muscle by laser photolysis of nitrophenyl-EGTA.
AuthorsMartin H, Bell MG, Ellis-Davies GC, Barsotti RJ
JournalBiophys J
PubMed ID14747333
The kinetics of Ca(2+)-induced contractions of chemically skinned guinea pig trabeculae was studied using laser photolysis of NP-EGTA. The amount of free Ca(2+) released was altered by varying the output from a frequency-doubled ruby laser focused on the trabeculae, while maintaining constant total [NP-EGTA] and [Ca(2+)]. The time courses of ... More
The voltage sensitive Lc-type Ca2+ channel is functionally coupled to the exocytotic machinery.
AuthorsWiser O, Trus M, Hernández A, Renström E, Barg S, Rorsman P, Atlas D
JournalProc Natl Acad Sci U S A
PubMed ID9874804
Although N- and P-type Ca2+ channels predominant in fast-secreting systems, Lc-type Ca2+ channels (C-class) can play a similar role in certain secretory cells and synapses. For example, in retinal bipolar cells, Ca2+ entry through the Lc channels triggers ultrafast exocytosis, and in pancreatic beta-cells, evoked secretion is highly sensitive to ... More
Oscillations in ciliary beat frequency and intracellular calcium concentration in rabbit tracheal epithelial cells induced by ATP.
AuthorsZhang L, Sanderson MJ
JournalJ Physiol
PubMed ID12563000
To investigate how Ca(2+) regulates airway ciliary activity, changes in ciliary beat frequency (CBF) and intracellular calcium concentration ([Ca(2+)](i)) of rabbit tracheal ciliated cells, in response to ATP, were simultaneously quantified with high-speed phase-contrast and fast fluorescence imaging. [ATP]<or= 1 microM induced an increase in [Ca(2+)](i) and CBF that declined ... More
Calcium buffering and protection from excitotoxic cell death by exogenous calbindin-D28k in HEK 293 cells.
AuthorsRintoul GL, Raymond LA, Baimbridge KG
JournalCell Calcium
PubMed ID11243935
Calbindin-D28k (CaBP) is a calcium-binding protein found in specific neuronal populations in the mammalian brain that, as a result of its proposed calcium-buffering action, may protect neurons against potentially harmful increases in intracellular calcium. We have stably transfected HEK 293 cells with recombinant human CaBP in order to determine the ... More
Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore. Invariance of Ca2+ binding as a function of sarcomere length.
AuthorsPatel JR, McDonald KS, Wolff MR, Moss RL
JournalJ Biol Chem
PubMed ID9038224
Ca2+ sensitivity of tension varies with sarcomere length in both skeletal and cardiac muscles. One possible explanation for this effect is that the Ca2+ affinity of the regulatory protein troponin C decreases when sarcomere length is reduced. To examine length dependence of Ca2+ binding to troponin C in skeletal muscle, ... More
Domain zipping and unzipping modulates TRPM4's properties in human cardiac conduction disease.
Authors
JournalFASEB J
PubMed ID32681584
Local Resting Ca2+ Controls the Scale of Astroglial Ca2+ Signals.
Authors
JournalCell Rep
PubMed ID32160550
Cell Mechanics at the Rear Act to Steer the Direction of Cell Migration.