scholarly journals Control of inositol 1,4,5-trisphosphate-induced Ca2+ release by cytosolic Ca2+

1995 ◽  
Vol 306 (2) ◽  
pp. 445-451 ◽  
Author(s):  
M D Bootman ◽  
L Missiaen ◽  
J B Parys ◽  
H De Smedt ◽  
R Casteels
Keyword(s):  
Binding Site ◽  
Cell Types ◽  
Inhibitory Effects ◽  
Activation Curve ◽  
Hormonal Stimulation ◽  
A7r5 Cells ◽  
Inositol 1,4,5 Trisphosphate ◽  
Insp3 Receptors ◽  
Dependent Inhibition ◽  
Stimulation Of

The synergistic action of cytosolic Ca2+ and inositol 1,4,5-trisphosphate (InsP3) in releasing intracellular Ca2+ stores has been suggested to be responsible for the complex intracellular Ca2 signals observed during hormonal stimulation of many cell types. However, the ability of cytosolic Ca2+ to potentiate Ca2+ release has recently been questioned because of the observed inhibitory effects of Ca2+ chelators used in previous studies. In the present study, EGTA and BAPTA [1,2-bis-(2-amino-phenoxy)ethane- NNN'N′-tetra-acetic acid] poorly inhibited InsP3-induced Ca2+ release from permeabilized A7r5 smooth-muscle cells. Additionally, stimulatory effects of cytosolic and luminal Ca2+ were observed either in the complete absence of Ca2+ chelator or at constant Ca(2+)-free chelator concentration. These data suggest that potentiation of InsP3-induced Ca2+ release by Ca2+ in A7r5 cells reflects an interaction between Ca2+ and InsP3 receptors, rather than a decrease in chelator-dependent inhibition. The EC50 for activation of InsP3-induced Ca2+ release by cytosolic Ca2+ was unaffected by ATP, or by changing InsP3 concentration, although InsP3-induced Ca2+ release became less sensitive to the inhibitory effects of cytosolic Ca2+ as the InsP3 concentration was elevated. Increasing H+ or Mg2+ concentration shifted the Ca(2+)-activation curve towards higher Ca2+ concentrations. These data suggest that, in addition to the InsP3-binding site, the affinity of the Ca(2+)-binding site(s) on InsP3 receptors can be modulated by intracellular cations.

scholarly journals Characterization of the inositol 1,4,5-trisphosphate-induced calcium release from permeabilized endocrine cells and its inhibition by decavanadate and p-hydroxymercuribenzoate

1989 ◽  
Vol 262 (1) ◽  
pp. 83-89 ◽  
Author(s):  
K J Föhr ◽  
J Scott ◽  
G Ahnert-Hilger ◽  
M Gratzl
Keyword(s):  
Endocrine Cells ◽  
Calcium Release ◽  
Cell Types ◽  
Inhibitory Effect ◽  
Maximal Effect ◽  
Thiol Compounds ◽  
Inositol 1,4,5 Trisphosphate ◽  
Dependent Inhibition ◽  
Pheochromocytoma Pc12 ◽  
First Time

The inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ compartment of endocrine cells was studied with alpha-toxin- and digitonin-permeabilized rat insulinoma (RINA2) and rat pheochromocytoma (PC12) cells. The Ca2+ uptake was ATP-dependent, and submicromolar concentrations of IP3 specifically released the stored Ca2+. Half-maximal Ca2+ release was observed with 0.25-0.5 mumol of IP3/l, and the amount of Ca2+ released due to IP3 could be enhanced by additional loading of the Ca2+ compartment. Consecutive additions of the same concentration of IP3 for 1-2 h always released the same amount of Ca2+ without desensitization, providing an ideal basis to further characterize the IP3-induced Ca2+ release. Here we describe for the first time a reversible inhibitory effect of decavanadate on the IP3-induced Ca2+ release. Among the vanadium species tested (decavanadate, oligovanadate and monovanadate), only decavanadate was inhibitory, with a half-maximal effect at 5 mumol/l in both cell types. The effect of decavanadate could be overcome by increasing the amount of sequestered Ca2+ or added IP3. Decavanadate did not affect the ATP-driven Ca2+ uptake but oligovanadate was inhibitory on Ca2+ uptake. p-Hydroxymercuribenzoate (pHMB) at concentrations between 10 and 30 mumol/l also inhibited the Ca2+ release due to IP3. Thiol compounds such as dithiothreitol (DTT; 1 mmol/l) added before pHMB removed all its inhibitory effect on the IP3-induced Ca2+ release, whereas the inhibition caused by decavanadate was unaffected by DTT. Thus, the decavanadate-dependent inhibition functions by a distinctly different mechanism than pHMB and could serve as a specific tool to analyse various aspects of the IP3-induced Ca2+ release within endocrine cells.

scholarly journals Effect of adenine nucleotides on myo-inositol-1,4,5-trisphosphate-induced calcium release

1997 ◽  
Vol 325 (3) ◽  
pp. 661-666 ◽  
Author(s):  
Ludwig MISSIAEN ◽  
Jan B. PARYS ◽  
Humbert DE SMEDT ◽  
Ilse SIENAERT ◽  
Henk SIPMA ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Binding Site ◽  
Calcium Release ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Release Process ◽  
A7r5 Cells ◽  
Channel Opening ◽  
Inositol 1,4,5 Trisphosphate

The effects of a whole series of adenine nucleotides on Ins(1,4,5)P3-induced Ca2+ release were characterized in permeabilized A7r5 smooth-muscle cells. Several adenine nucleotides activated the Ins(1,4,5)P3 receptor. It was observed that 3′-phosphoadenosine 5′-phosphosulphate, CoA, di(adenosine-5′)tetraphosphate (Ap4A) and di(adenosine-5′)pentaphosphate (Ap5A) were more effective than ATP. Ap4A and Ap5A also interacted with a lower EC50 than ATP. In order to find out how these adenine nucleotides affected Ins(1,4,5)P3-induced Ca2+ release, we have measured their effect on the response of permeabilized A7r5 cells to a progressively increasing Ins(1,4,5)P3 concentration. Stimulatory ATP and Ap5A concentrations had no effect on the threshold Ins(1,4,5)P3 concentration for initiating Ca2+ release, but they stimulated Ca2+ release in the presence of supra-threshold Ins(1,4,5)P3 concentrations by increasing the co-operativity of the release process. Inhibition of the Ins(1,4,5)P3-induced Ca2+ release at higher ATP concentrations was associated with a further increase in co-operativity and also with a shift in threshold towards higher Ins(1,4,5)P3 concentrations. ATP had no effect on the non-specific Ca2+ leak in the absence of Ins(1,4,5)P3. We conclude that the adenine-nucleotide-binding site can be activated by many different adenine nucleotides. Binding of these compounds to the transducing domain of the Ins(1,4,5)P3 receptor increases the efficiency of transmitting Ins(1,4,5)P3 binding to channel opening. The inhibition by high ATP concentrations is exerted at a different site, related to Ins(1,4,5)P3 binding.

scholarly journals Ca2+ entry into PC12 cells initiated by ryanodine receptors or inositol 1,4,5-trisphosphate receptors

1998 ◽  
Vol 329 (2) ◽  
pp. 349-357 ◽  
Author(s):  
L. Deborah BENNETT ◽  
D. Martin BOOTMAN ◽  
J. Michael BERRIDGE ◽  
R. Timothy CHEEK
Keyword(s):  
Endoplasmic Reticulum ◽  
Pc12 Cells ◽  
Ryanodine Receptors ◽  
Half Time ◽  
Free Medium ◽  
Excitable Cells ◽  
Inositol 1,4,5 Trisphosphate ◽  
Insp3 Receptors ◽  
Universal Mechanism ◽  
Stimulation Of

Capacitative Ca2+ entry (CCE) is a universal mechanism for refilling intracellular Ca2+ stores in electrically non-excitable cells. The situation in excitable cells is less clear, however, since they may rely on other entry mechanisms for Ca2+-store refilling. In the present study we investigated CCE in intact PC12 cells, using acetylcholine to bring about activation of InsP3 receptors (InsP3Rs), caffeine to activate ryanodine receptors (RyRs) and thapsigargin to inhibit sarco/endoplasmic reticulum Ca2+-ATPase pumps. We found that depletion of the InsP3-, caffeine- or thapsigargin-sensitive stores promoted Ca2+ entry, suggesting that stimulation of either InsP3Rs or RyRs can activate CCE. The CCE pathways activated by InsP3Rs, RyRs and thapsigargin appeared to be independent at least in part, since their effects were found to be additive. However, CCE triggered by caffeine, acetylcholine or thapsigargin progressively diminished with time. The decay of CCE caused by one agent also inhibited subsequent responses to the others, suggesting that some component of the CCE pathway is common to all intracellular Ca2+ stores. The magnitude of CCE stimulated by InsP3Rs or RyRs was related to the size of the stores; the InsP3-sensitive store was smaller than the RyR-sensitive store and triggered a smaller entry component. However, both stores filled with a similar half time (about 1 min), and both could be filled more rapidly by depolarization-induced Ca2+ entry through voltage-operated channels. A significant basal Ca2+ influx was apparent in PC12 cells. The basal entry component may be under the control of the InsP3-sensitive Ca2+ store, since short incubations in Ca2+-free medium depleted this store.

scholarly journals Dual Regulation of Calcium Mobilization by Inositol 1,4,5-Trisphosphate in a Living Cell

2000 ◽  
Vol 115 (4) ◽  
pp. 481-490 ◽  
Author(s):  
Svetlana Tertyshnikova ◽  
Alan Fein
Keyword(s):  
Gene Expression ◽  
Living Cell ◽  
Enzyme Activation ◽  
Sustained Response ◽  
Common Mechanism ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Inositol 1,4,5 Trisphosphate ◽  
Dependent Inhibition ◽  
Stimulation Of

Changes in cytosolic free calcium ([Ca2+]i) often take the form of a sustained response or repetitive oscillations. The frequency and amplitude of [Ca2+]i oscillations are essential for the selective stimulation of gene expression and for enzyme activation. However, the mechanism that determines whether [Ca2+]i oscillates at a particular frequency or becomes a sustained response is poorly understood. We find that [Ca2+]i oscillations in rat megakaryocytes, as in other cells, results from a Ca2+-dependent inhibition of inositol 1,4,5-trisphosphate (IP3)–induced Ca2+ release. Moreover, we find that this inhibition becomes progressively less effective with higher IP3 concentrations. We suggest that disinhibition, by increasing IP3 concentration, of Ca2+-dependent inhibition is a common mechanism for the regulation of [Ca2+]i oscillations in cells containing IP3-sensitive Ca2+ stores.

scholarly journals Effect of inositol 1,4,5-trisphosphate receptor stimulation on mitochondrial [Ca2+] and secretion in chromaffin cells

2002 ◽  
Vol 365 (2) ◽  
pp. 451-459 ◽  
Author(s):  
Mayte MONTERO ◽  
Maria Teresa ALONSO ◽  
Almudena ALBILLOS ◽  
Inmaculada CUCHILLO-IBÁÑEZ ◽  
Román OLIVARES ◽  
...  
Keyword(s):  
Chromaffin Cells ◽  
Ryanodine Receptors ◽  
Catecholamine Secretion ◽  
Mitochondrial Inhibitors ◽  
High K ◽  
Inositol 1,4,5 Trisphosphate ◽  
Insp3 Receptors ◽  
Voltage Dependent ◽  
Trisphosphate Receptor ◽  
Stimulation Of

Ca2+ uptake by mitochondria is a potentially important buffering system able to control cytosolic [Ca2+]. In chromaffin cells, we have shown previously that stimulation of either Ca2+ entry or Ca2+ release via ryanodine receptors triggers large increases in mitochondrial [Ca2+] ([Ca2+]M) approaching the millimolar range, whose blockade dramatically enhances catecholamine secretion [Montero, Alonso, Carnicero, Cuchillo-Ibañez, Albillos, Garcia, Carcia-Sancho and Alvarez (2000) Nat. Cell Biol. 2, 57–61]. In the present study, we have studied the effect of stimulation of inositol 1,4,5-trisphosphate (InsP3) receptors using histamine. We find that histamine produces a heterogeneous increase in [Ca2+]M, reaching peak levels at approx. 1μM in 70% of the mitochondrial space to several hundred micromolar in 2–3% of mitochondria. Intermediate levels were found in the rest of the mitochondrial space. Single-cell imaging experiments with aequorin showed that the heterogeneity had both an intercellular and a subcellular origin. Those mitochondria responding to histamine with increases in [Ca2+]M much greater than 1μM (30%) were the same as those that also responded with large increases in [Ca2+]M following stimulation with either high-K+ medium or caffeine. Blocking mitochondrial Ca2+ uptake with protonophores or mitochondrial inhibitors also enhanced catecholamine secretion induced by histamine. These results suggest that some InsP3 receptors tightly co-localize with ryanodine receptors and voltage-dependent Ca2+ channels in defined subplasmalemmal functional units designed to control secretion induced by different stimuli.

Intracellular calcium and the regulation of sodium transport in the frog skin

1978 ◽  
Vol 202 (1148) ◽  
pp. 353-360 ◽  
Keyword(s):  
Cell Types ◽  
Metabolic Inhibitors ◽  
Transepithelial Transport ◽  
Cytoplasmic Calcium ◽  
Inhibitory Effects ◽  
Na Transport ◽  
Transepithelial Na Transport ◽  
Ca Uptake ◽  
Basal Border ◽  
Stimulation Of

Exposure of frog skins to Na-free solutions on the basal border causes a reduction in transepithelial Na transport. Since Na-free solutions produce an increase in cell Ca concentration in some cell types, we have explored whether such increase plays a rôle in their inhibitory effects on transepithelial transport. Measurements of 45 Ca uptake in isolated epithelia showed that Na-free solutions caused a threefold stimulation of Ca uptake; nearly all the increased uptake occurred through the basal border. The reduction in transepithelial Na transport caused by Na-free solutions was absent when Ca was also eliminated from the basal solution. These findings suggest that the reduction in transepithelial Na-free solutions is caused by increased cytoplasmic calcium levels. We also found that during the action of metabolic inhibitors, Ca efflux from the epithelium was increased markedly. Since such as increase in efflux is probably due to increased (Ca) in the cytoplasm, we suggest that the reduced epithelial Na permeability observed during metabolic inhibition may be due to increased cytoplasmic calcium.

Hormonal stimulation of myoblast differentiation in the absence of DNA synthesis

1982 ◽  
Vol 243 (5) ◽  
pp. C278-C284 ◽  
Author(s):  
K. A. Turo ◽  
J. R. Florini
Keyword(s):  
Creatine Kinase ◽  
Cell Differentiation ◽  
Dna Synthesis ◽  
Muscle Cell ◽  
Fold Increase ◽  
Cell Types ◽  
Myoblast Differentiation ◽  
Hormonal Stimulation ◽  
Muscle Cell Differentiation ◽  
Stimulation Of

The role of DNA synthesis in the final stages of muscle cell differentiation has been a subject of controversy for more than a decade. In an attempt to resolve disagreements over the necessity for a unique (or "quantal") mitosis just prior to the conversion of proliferating myoblasts to form postmitotic myotubes, we have studied the effects of insulin and somatomedin on the stimulation of myoblast differentiation with or without DNA synthesis. Under conditions in which at least 95% of [3H]thymidine incorporation was blocked by cytosine arabinoside, there was a 5- to 10-fold increase in the extent of differentiation (determined as fusion or creatine kinase elevation) on addition of insulin or multiplication-stimulating activity. The effect of the hormones was on myoblast differentiation, not enzyme induction; insulin did not cause any increase in creatine kinase when it was added to performed myotubes. These studies were done using two different cell types, Yaffe's L6 cell line and Japanese quail myoblasts in serum-free media; we obtained similar results in both. Our results are not compatible with the view that a quantal mitosis is required at a late stage of muscle cell differentiation.

scholarly journals Calcium puffs are generic InsP3-activated elementary calcium signals and are downregulated by prolonged hormonal stimulation to inhibit cellular calcium responses

2001 ◽  
Vol 114 (22) ◽  
pp. 3979-3989 ◽  
Author(s):  
Stephen C. Tovey ◽  
Patrick de Smet ◽  
Peter Lipp ◽  
David Thomas ◽  
Kenneth W. Young ◽  
...  
Keyword(s):  
Neuroblastoma Cells ◽  
Building Blocks ◽  
Cell Types ◽  
Cellular Responses ◽  
Hormonal Stimulation ◽  
Receptor Isoforms ◽  
Inositol 1,4,5 Trisphosphate ◽  
Trisphosphate Receptor ◽  
Calcium Puffs ◽  
Kinetics Of

Elementary Ca2+ signals, such as ‘Ca2+ puffs’, which arise from the activation of inositol 1,4,5-trisphosphate receptors, are building blocks for local and global Ca2+ signalling. We characterized Ca2+ puffs in six cell types that expressed differing ratios of the three inositol 1,4,5-trisphosphate receptor isoforms. The amplitudes, spatial spreads and kinetics of the events were similar in each of the cell types. The resemblance of Ca2+ puffs in these cell types suggests that they are a generic elementary Ca2+ signal and, furthermore, that the different inositol 1,4,5-trisphosphate isoforms are functionally redundant at the level of subcellular Ca2+ signalling. Hormonal stimulation of SH-SY5Y neuroblastoma cells and HeLa cells for several hours downregulated inositol 1,4,5-trisphosphate expression and concomitantly altered the properties of the Ca2+ puffs. The amplitude and duration of Ca2+ puffs were substantially reduced. In addition, the number of Ca2+ puff sites active during the onset of a Ca2+ wave declined. The consequence of the changes in Ca2+ puff properties was that cells displayed a lower propensity to trigger regenerative Ca2+ waves. Therefore, Ca2+ puffs underlie inositol 1,4,5-trisphosphate signalling in diverse cell types and are focal points for regulation of cellular responses.

Enhancement of Plasminogen Binding to U937 Cells and Fibrin by Complestatin

1997 ◽  
Vol 77 (01) ◽  
pp. 137-142 ◽  
Author(s):  
Kiyoshi Tachikawa ◽  
Keiji Hasurni ◽  
Akira Endo
Keyword(s):  
Binding Site ◽  
Binding Affinity ◽  
Blood Cells ◽  
Aminocaproic Acid ◽  
U937 Cells ◽  
Biochemical Basis ◽  
Equilibrium Binding ◽  
Pharmacological Stimulation ◽  
Endogenous Fibrinolysis ◽  
Stimulation Of

SummaryPlasminogen binds to endothelial and blood cells as well as to fibrin, where the zymogen is efficiently activated and protected from inhibition by α2-antiplasmin. In the present study we have found that complestatin, a peptide-like metabolite of a streptomyces, enhances binding of plasminogen to cells and fibrin. Complestatin, at concentrations ranging from 1 to 5 μM, doubled 125I-plasminogen binding to U937 cells both in the absence and presence of lipoprotein(a), a putative physiological competitor of plasminogen. The binding of 125I-plasminogen in the presence of complestatin was abolished by e-aminocaproic acid, suggesting that the lysine binding site(s) of the plasminogen molecule are involved in the binding. Equilibrium binding analyses indicated that complestatin increased the maximum binding of 125I-plasminogen to U937 cells without affecting the binding affinity. Complestatin was also effective in increasing 125I-plasminogen binding to fibrin, causing 2-fold elevation of the binding at ~1 μM. Along with the potentiation of plasminogen binding, complestatin enhanced plasmin formation, and thereby increased fibrinolysis. These results would provide a biochemical basis for a pharmacological stimulation of endogenous fibrinolysis through a promotion of plasminogen binding to cells and fibrin.

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