scholarly journals Calmidazolium and arachidonate activate a calcium entry pathway that is distinct from store-operated calcium influx in HeLa cells

2004 ◽  
Vol 381 (3) ◽  
pp. 929-939 ◽  
Author(s):  
Claire M. PEPPIATT ◽  
Anthony M. HOLMES ◽  
Jeong T. SEO ◽  
Martin D. BOOTMAN ◽  
Tony J. COLLINS ◽  
...  
Keyword(s):  
Hela Cells ◽  
Calcium Influx ◽  
Differential Sensitivity ◽  
Excitable Cells ◽  
Hormonal Stimulation ◽  
Calmodulin Antagonist ◽  
Alternative Pathways ◽  
Entry Pathway ◽  
Store Depletion ◽  
Stimulation Of

Agonists that deplete intracellular Ca2+ stores also activate Ca2+ entry, although the mechanism by which store release and Ca2+ influx are linked is unclear. A potential mechanism involves ‘store-operated channels’ that respond to depletion of the intracellular Ca2+ pool. Although SOCE (store-operated Ca2+ entry) has been considered to be the principal route for Ca2+ entry during hormonal stimulation of non-electrically excitable cells, recent evidence has suggested that alternative pathways activated by metabolites such as arachidonic acid are responsible for physiological Ca2+ influx. It is not clear whether such messenger-activated pathways exist in all cells, whether they are truly distinct from SOCE and which metabolites are involved. In the present study, we demonstrate that HeLa cells express two pharmacologically and mechanistically distinct Ca2+ entry pathways. One is the ubiquitous SOCE route and the other is an arachidonate-sensitive non-SOCE. We show that both these Ca2+ entry pathways can provide long-lasting Ca2+ elevations, but that the channels are not the same, based on their differential sensitivity to 2-aminoethoxydiphenyl borate, LOE-908 {(R,S)-(3,4-dihydro-6,7-dimethoxy-isochinolin-1-yl)-2-phenyl-N,N-di[2-(2,3,4-trimethoxyphenyl)ethyl]acetamid mesylate} and gadolinium. In addition, non-SOCE and not SOCE was permeable to strontium. Furthermore, unlike SOCE, the non-SOCE pathway did not require store depletion and was not sensitive to displacement of the endoplasmic reticulum from the plasma membrane using jasplakinolide or ionomycin pretreatment. These pathways did not conduct Ca2+ simultaneously due to the dominant effect of arachidonate, which rapidly curtails SOCE and promotes Ca2+ influx via non-SOCE. Although non-SOCE could be activated by exogenous application of arachidonate, the most robust method for stimulation of this pathway was application of the widely used calmodulin antagonist calmidazolium, due to its ability to activate phospholipase A2.

Store depletion and calcium influx

1997 ◽  
Vol 77 (4) ◽  
pp. 901-930 ◽  
Author(s):  
A. B. Parekh ◽  
R. Penner
Keyword(s):  
Molecular Mechanisms ◽  
Calcium Influx ◽  
Regulatory Mechanisms ◽  
Patch Clamp Technique ◽  
Electrophysiological Properties ◽  
Entry Pathway ◽  
Store Depletion ◽  
Proliferation And Apoptosis ◽  
Ca2 Channels ◽  
Intense Research

Calcium influx in nonexcitable cells regulates such diverse processes as exocytosis, contraction, enzyme control, gene regulation, cell proliferation, and apoptosis. The dominant Ca2+ entry pathway in these cells is the store-operated one, in which Ca2+ entry is governed by the Ca2+ content of the agonist-sensitive intracellular Ca2+ stores. Only recently has a Ca2+ current been described that is activated by store depletion. The properties of this new current, called Ca2+ release-activated Ca2+ current (ICRAC), have been investigated in detail using the patch-clamp technique. Despite intense research, the nature of the signal that couples Ca2+ store content to the Ca2+ channels in the plasma membrane has remained elusive. Although ICRAC appears to be the most effective and widespread influx pathway, other store-operated currents have also been observed. Although the Ca2+ release-activated Ca2+ channel has not yet been cloned, evidence continues to accumulate that the Drosophila trp gene might encode a store-operated Ca2+ channel. In this review, we describe the historical development of the field of Ca2+ signaling and the discovery of store-operated Ca2+ currents. We focus on the electrophysiological properties of the prototype store-operated current ICRAC, discuss the regulatory mechanisms that control it, and finally consider recent advances toward the identification of molecular mechanisms involved in this ubiquitous and important Ca2+ entry pathway.

scholarly journals Increased intracellular Ca2+ induces Ca2+ influx in human T lymphocytes.

1993 ◽  
Vol 4 (2) ◽  
pp. 173-184 ◽  
Author(s):  
D M Haverstick ◽  
L S Gray
Keyword(s):  
Intracellular Concentration ◽  
Jurkat Cells ◽  
Tumor Promoter ◽  
Excitable Cells ◽  
Entry Pathway ◽  
Internal Storage ◽  
Human T Lymphocyte ◽  
Lymphocyte Cell ◽  
Lymphocyte Cell Line ◽  
Stimulation Of

One current hypothesis for the initiation of Ca2+ entry into nonelectrically excitable cells proposes that Ca2+ entry is linked to the state of filling of intracellular Ca2+ stores. In the human T lymphocyte cell line Jurkat, stimulation of the antigen receptor leads to release of Ca2+ from internal stores and influx of extracellular Ca2+. Similarly, treatment of Jurkat cells with the tumor promoter thapsigargin induced release of Ca2+ from internal stores and also resulted in influx of extracellular Ca2+. Initiation of Ca2+ entry by thapsigargin was blocked by chelation of Ca2+ released from the internal storage pool. The Ca2+ entry pathway also could be initiated by an increase in the intracellular concentration of Ca2+ after photolysis of the Ca(2+)-cage, nitr-5. Thus, three separate treatments that caused an increase in the intracellular concentration of Ca2+ initiated Ca2+ influx in Jurkat cells. In all cases, Ca(2+)-initiated Ca2+ influx was blocked by treatment with any of three phenothiazines or W-7, suggesting that it is mediated by calmodulin. These data suggest that release of Ca2+ from internal stores is not linked capacitatively to Ca2+ entry but that initiation is linked instead by Ca2+ itself, perhaps via calmodulin.

scholarly journals Participation of phospholipase A2 isoforms in the control of calcium influx into electrically non-excitable cells.

2000 ◽  
Vol 47 (3) ◽  
pp. 591-599 ◽  
Author(s):  
K Zabłocki ◽  
M Waśniewska ◽  
J Duszyński
Keyword(s):  
Phospholipase A2 ◽  
Cell Lines ◽  
Calcium Influx ◽  
Mdck Cells ◽  
Significant Inhibition ◽  
Jurkat Cells ◽  
Excitable Cells ◽  
Secreted Phospholipase A2 ◽  
Calcium Independent Phospholipase A2 ◽  
Stimulation Of

The participation of phospholipase A2 isoforms in capacitative store-operated Ca2+ influx into Jurkat leukemic T and MDCK cells was investigated. Preincubation of Jurkat cells with either bromophenacyl bromide (an inhibitor of secreted phospholipase A2, sPLA2) or Helss (an inhibitor of calcium independent phospholipase A2--iPLA2) resulted in a significant inhibition of the calcium influx. The extent of this inhibition depended on the pH of the extracellular millieu; it increased with alkalisation. The rate of Ca2+ influx into MDCK cells was reduced by bromophenacyl bromide. Preincubation of these cells with Helss resulted in the stimulation of the influx. These observations suggest the participation of different PLA2 isoforms in the regulation of Ca2+ influx. They also show that the extent that PLA2 isoforms control the influx depends on the pH of the medium. Finally, these data indicate that various phospholipase A2 isoforms may play a role in the control of Ca2+ influx in different cell lines.

scholarly journals Thermal Mechanisms of Millimeter Wave Stimulation of Excitable Cells

2013 ◽  
Vol 104 (12) ◽  
pp. 2622-2628 ◽  
Author(s):  
Mikhail G. Shapiro ◽  
Michael F. Priest ◽  
Peter H. Siegel ◽  
Francisco Bezanilla
Keyword(s):  
Millimeter Wave ◽  
Excitable Cells ◽  
Stimulation Of

scholarly journals African Swine Fever Virus Gets Undressed: New Insights on the Entry Pathway

2016 ◽  
Vol 91 (4) ◽  
Author(s):  
Germán Andrés
Keyword(s):  
African Swine Fever Virus ◽  
Structural Complexity ◽  
African Swine Fever ◽  
Low Ph ◽  
Fever Virus ◽  
Dna Virus ◽  
Alternative Pathways ◽  
Entry Pathway ◽  
A Genome ◽  
Inner Envelope

ABSTRACT African swine fever virus (ASFV) is a large, multienveloped DNA virus composed of a genome-containing core successively wrapped by an inner lipid envelope, an icosahedral protein capsid, and an outer lipid envelope. In keeping with this structural complexity, recent studies have revealed an intricate entry program. This Gem highlights how ASFV uses two alternative pathways, macropinocytosis and clathrin-mediated endocytosis, to enter into the host macrophage and how the endocytosed particles undergo a stepwise, low pH-driven disassembly leading to inner envelope fusion and core delivery in the cytoplasm.

scholarly journals Seminalplasmin. An endogenous calmodulin antagonist

1985 ◽  
Vol 230 (1) ◽  
pp. 277-280 ◽  
Author(s):  
K Gietzen ◽  
H J Galla
Keyword(s):  
Basic Protein ◽  
Electrostatic Forces ◽  
High Potency ◽  
Calmodulin Antagonist ◽  
Basal Activity ◽  
Bull Semen ◽  
Stimulation Of

Seminalplasmin, a strongly basic protein isolated from bull semen, was found to antagonize with high potency and extraordinary specificity the function of calmodulin. Calmodulin antagonism is the result of an interaction between the two proteins, which is mainly determined by electrostatic forces. The stimulation of Ca2+-transporting ATPase and phosphodiesterase by calmodulin was half-maximally inhibited at approx. 0.1 microM-seminalplasmin. However, the basal activity of calmodulin-dependent enzymes was not significantly altered by seminalplasmin over the concentration range investigated.

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