Spatially confined diffusion of calcium in dendrites of hippocampal neurons revealed by flash photolysis of caged calcium.
AuthorsKorkotian E, Segal M
JournalCell Calcium
PubMed ID17064764
'The extent of diffusion of a locally evoked calcium surge in dendrites of cultured hippocampal neurons was studied by flash photolysis of caged EGTA. Cells were transfected with pDsRed for visualization, preincubated with caged NP-EGTA (AM) and Fluo-4 (AM) at room temperature and imaged in a PASCAL confocal microscope. Pulses ... More
Novel approach to real-time flash photolysis and confocal [Ca2+] imaging.
AuthorsSobie EA, Kao JP, Lederer WJ,
JournalPflugers Arch
PubMed ID17323075
'Flash photolysis of “caged” compounds using ultraviolet light is a powerful experimental technique for producing rapid changes in concentrations of bioactive signaling molecules. Studies that employ this technique have used diverse strategies for controlling the spatial and temporal application of light to the specimen. Here we describe a new system ... More
Calcium-induced acrosomal exocytosis requires cAMP acting through a protein kinase A-independent, Epac-mediated pathway.
AuthorsBranham MT, Mayorga LS, Tomes CN
JournalJ Biol Chem
PubMed ID16407249
'Epac, a guanine nucleotide exchange factor for the small GTPase Rap, binds to and is activated by the second messenger cAMP. In sperm, there are a number of signaling pathways required to achieve egg-fertilizing ability that depend upon an intracellular rise of cAMP. Most of these processes were thought to ... More
Contribution of ryanodine receptor subtype 3 to ca2+ responses in Ca2+-overloaded cultured rat portal vein myocytes.
'Using an antisense strategy, we have previously shown that in vascular myocytes, subtypes 1 and 2 of ryanodine receptors (RYRs) are required for Ca(2+) release during Ca(2+) sparks and global Ca(2+) responses, evoked by activation of voltage-gated Ca(2+) channels, whereas RYR subtype 3 (RYR3) has no contribution. Here, we investigated ... More
UV photolysis using a micromanipulated optical fiber to deliver UV energy directly to the sample.
AuthorsParpura V, Haydon PG
JournalJ Neurosci Methods
PubMed ID10065991
'UV photolysis of caged molecules is a powerful method for studying cellular signaling. However, UV energy is often delivered through the microscope objective which can make certain experiments difficult. We have evaluated the utility of delivering UV pulses directly to the sample through an optical fiber. Visible (635 nm) and ... More
Turning of nerve growth cones induced by localized increases in intracellular calcium ions.
AuthorsZheng JQ
JournalNature
PubMed ID10638759
'Guidance of developing axons involves turning of the motile tip, the growth cone, in response to a variety of extracellular cues. Little is known about the intracellular mechanism by which the directional signal is transduced. Ca2+ is a key second messenger in growth cone extension and has been implicated in ... More
Localized Ca2+ uncaging reveals polarized distribution of Ca2+-sensitive Ca2+ release sites: mechanism of unidirectional Ca2+ waves.
AuthorsAshby MC, Craske M, Park MK, Gerasimenko OV, Burgoyne RD, Petersen OH, Tepikin AV
JournalJ Cell Biol
PubMed ID12119355
'Ca2+-induced Ca2+ release (CICR) plays an important role in the generation of cytosolic Ca2+ signals in many cell types. However, it is inherently difficult to distinguish experimentally between the contributions of messenger-induced Ca2+ release and CICR. We have directly tested the CICR sensitivity of different regions of intact pancreatic acinar ... More
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
Filopodia that extend from neuronal growth cones sample the environment for extracellular guidance cues, but the signals they transmit to growth cones are unknown. Filopodia were observed generating localized transient elevations of intracellular calcium ([Ca2+]i) that propagate back to the growth cone and stimulate global Ca2+ elevations. The frequency of ... More
Differential outgrowth of axons and their branches is regulated by localized calcium transients.
AuthorsHutchins BI, Kalil K,
JournalJ Neurosci
PubMed ID18171932
During development axon outgrowth and branching are independently regulated such that axons can stall or retract while their interstitial branches extend toward targets. Previous studies have shown that guidance cues and intracellular signaling components can promote branching of cortical axons without affecting axon outgrowth. However, the mechanisms that regulate differential ... More
Restricted photorelease of biologically active molecules near the plasma membrane.
AuthorsSuga T, Hirano M, Takayanagi M, Koshimoto H, Watanabe A
JournalBiochem Biophys Res Commun
PubMed ID9878552
An evanescent wave of ultraviolet light was successfully used to release biologically active molecules from caged compounds in living cells. The evanescent wave was generated by the total internal reflection in a limited region near the plasma membrane attached to the illuminated interface. At first, the photolysis efficiency of the ... 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
The endoplasmic reticulum as one continuous Ca(2+) pool: visualization of rapid Ca(2+) movements and equilibration.
AuthorsPark MK, Petersen OH, Tepikin AV
JournalEMBO J
PubMed ID11060024
We investigated whether the endoplasmic reticulum (ER) is a functionally connected Ca(2+) store or is composed of separate subunits by monitoring movements of Ca(2+) and small fluorescent probes in the ER lumen of pancreatic acinar cells, using confocal microscopy, local bleaching and uncaging. We observed rapid movements and equilibration of ... More
An astrocytic basis of epilepsy.
AuthorsTian GF, Azmi H, Takano T, Xu Q, Peng W, Lin J, Oberheim N, Lou N, Wang X, Zielke HR, Kang J, Nedergaard M
JournalNat Med
PubMed ID16116433
Hypersynchronous neuronal firing is a hallmark of epilepsy, but the mechanisms underlying simultaneous activation of multiple neurons remains unknown. Epileptic discharges are in part initiated by a local depolarization shift that drives groups of neurons into synchronous bursting. In an attempt to define the cellular basis for hypersynchronous bursting activity, ... More
Selective induction of LTP and LTD by postsynaptic [Ca2+]i elevation.
AuthorsYang SN, Tang YG, Zucker RS
JournalJ Neurophysiol
PubMed ID10036277
Long-term potentiation (LTP) and long-term depression (LTD), two prominent forms of synaptic plasticity at glutamatergic afferents to CA1 hippocampal pyramidal cells, are both triggered by the elevation of postsynaptic intracellular calcium concentration ([Ca2+]i). To understand how one signaling molecule can be responsible for triggering two opposing forms of synaptic modulation, ... More
Selective stimulation of astrocyte calcium in situ does not affect neuronal excitatory synaptic activity.
Astrocytes are considered the third component of the synapse, responding to neurotransmitter release from synaptic terminals and releasing gliotransmitters--including glutamate--in a Ca(2+)-dependent manner to affect neuronal synaptic activity. Many studies reporting astrocyte-driven neuronal activity have evoked astrocyte Ca(2+) increases by application of endogenous ligands that directly activate neuronal receptors, making ... 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
Intracellular calcium dependence of transmitter release rates at a fast central synapse.
AuthorsSchneggenburger R, Neher E
JournalNature
PubMed ID10972290
Calcium-triggered fusion of synaptic vesicles and neurotransmitter release are fundamental signalling steps in the central nervous system. It is generally assumed that fast transmitter release is triggered by elevations in intracellular calcium concentration ([Ca2+]i) to at least 100 microM near the sites of vesicle fusion. For synapses in the central ... More
Threshold calcium levels for lamellar body exocytosis in type II pneumocytes.
AuthorsHaller T, Auktor K, Frick M, Mair N, Dietl P
JournalAm J Physiol
PubMed ID10564173
Pulmonary surfactant is secreted via exocytosis of lamellar bodies (LBs) by alveolar type II cells. Here we analyzed the dependence of LB exocytosis on intracellular Ca(2+) concentration ([Ca(2+)](i)). In fura 2-loaded cells, [Ca(2+)](i) was selectively elevated by flash photolysis of a cell-permeant caged Ca(2+) compound (o-nitrophenyl EGTA-AM) or by gradually ... More
Activation of TRPM7 channels by phospholipase C-coupled receptor agonists.
AuthorsLangeslag M, Clark K, Moolenaar WH, van Leeuwen FN, Jalink K
JournalJ Biol Chem
PubMed ID17095511
TRPM7 is a ubiquitously expressed nonspecific cation channel that has been implicated in cellular Mg(2+) homeostasis. We have recently shown that moderate overexpression of TRPM7 in neuroblastoma N1E-115 cells elevates cytosolic Ca(2+) levels and enhances cell-matrix adhesion. Furthermore, activation of TRPM7 by phospholipase C (PLC)-coupled receptor agonists caused a further ... 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
Astrocytes can release glutamate in a calcium-dependent manner and consequently signal to adjacent neurons. Whether this glutamate release pathway is used during physiological signaling or is recruited only under pathophysiological conditions is not well defined. One reason for this lack of understanding is the limited knowledge about the levels of ... 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+-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
Micromanipulation by laser microbeam and optical tweezers: from plant cells to single molecules.
AuthorsGreulich KO, Pilarczyk G, Hoffmann A, Meyer Zu Hörste G, Schäfer B, Uhl V, Monajembashi S
JournalJ Microsc
PubMed ID10849196
Complete manipulation by laser light allows precise and gentle treatment of plant cells, subcellular structures, and even individual DNA molecules. Recently, affordable lasers have become available for the construction of microbeams as well as for optical tweezers. This may generate new interest in these tools for plant biologists. Early experiments, ... More
Exocytosis and endocytosis of small vesicles in PC12 cells studied with TEPIQ (two-photon extracellular polar-tracer imaging-based quantification) analysis.
AuthorsLiu TT, Kishimoto T, Hatakeyama H, Nemoto T, Takahashi N, Kasai H
JournalJ Physiol
PubMed ID16150796
We investigated exocytosis of PC12 cells using two-photon excitation imaging and extracellular polar tracers (TEP imaging) in the lateral membranes not facing the glass-cover slip. Upon photolysis of a caged Ca2+ compound, TEP imaging with FM1-43 (a polar membrane tracer) detected massive exocytosis of vesicles with a time constant of ... More
Uptake and release of Ca2+ by the endoplasmic reticulum contribute to the oscillations of the cytosolic Ca2+ concentration triggered by Ca2+ influx in the electrically excitable pancreatic B-cell.
AuthorsGilon P, Arredouani A, Gailly P, Gromada J, Henquin JC
JournalJ Biol Chem
PubMed ID10400636
The role of intracellular Ca2+ pools in oscillations of the cytosolic Ca2+ concentration ([Ca2+]c) triggered by Ca2+ influx was investigated in mouse pancreatic B-cells. [Ca2+]c oscillations occurring spontaneously during glucose stimulation or repetitively induced by pulses of high K+ (in the presence of diazoxide) were characterized by a descending phase ... 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
Piezo1-Mediated Ca2+ Activities Regulate Brain Vascular Pathfinding during Development.
Authors
JournalNeuron
PubMed ID32827455
Iron-deficiency anemia reduces cardiac contraction by downregulating RyR2 channels and suppressing SERCA pump activity.
Authors
JournalJCI Insight
PubMed ID30779710
IP3 mediated global Ca2+ signals arise through two temporally and spatially distinct modes of Ca2+ release.