Surfactant Releases Internal Calcium Stores in Neutrophils by G Protein-Mediated Pathway

2002 ◽  
Author(s):  
Mark E. Boston ◽  
G. C. Frech ◽  
Enrique Chacon-Cruz ◽  
E. S. Buescher ◽  
David G. Oelberg
Keyword(s):  
G Protein ◽  
Calcium Stores ◽  
Internal Calcium

Surfactant Releases Internal Calcium Stores in Neutrophils by G Protein–Activated Pathway

2004 ◽  
Vol 229 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Mark E. Boston ◽  
G. Christopher Frech ◽  
Enrique Chacon-Cruz ◽  
E. Stephen Buescher ◽  
David G. Oelberg
Keyword(s):  
G Protein ◽  
Calcium Stores ◽  
Internal Calcium

scholarly journals Inhibitory Effect of Somatostatin-14 on L-Type Voltage-Gated Calcium Channels in Cultured Cone Photoreceptors Requires Intracellular Calcium

2009 ◽  
Vol 102 (3) ◽  
pp. 1801-1810 ◽  
Author(s):  
Kuihuan Jian ◽  
Rola Barhoumi ◽  
Michael L. Ko ◽  
Gladys Y.-P. Ko
Keyword(s):  
Calcium Channels ◽  
Intracellular Calcium ◽  
G Protein ◽  
Inhibitory Effect ◽  
Calcium Stores ◽  
Dependent Effect ◽  
Voltage Gated ◽  
Circadian Phase ◽  
Voltage Gated Calcium Channels ◽  
Somatostatin 14

The inhibitory effects of somatostatin have been well documented for many physiological processes. The action of somatostatin is through G-protein-coupled receptor-mediated second-messenger signaling, which in turn affects other downstream targets including ion channels. In the retina, somatostatin is released from a specific class of amacrine cells. Here we report that there was a circadian phase-dependent effect of somatostatin-14 (SS14) on the L-type voltage-gated calcium channels (L-VGCCs) in cultured chicken cone photoreceptors, and our study reveals that this process is dependent on intracellular calcium stores. Application of 500 nM SS14 for 2 h caused a decrease in L-VGCC currents only during the subjective night but not the subjective day. We then explored the cellular mechanisms underlying the circadian phase-dependent effect of SS14. The inhibitory effect of SS14 on L-VGCCs was mediated through the pertussis-toxin-sensitive G-protein-dependent somatostatin receptor 2 (sst2). Activation of sst2 by SS14 further activated downstream signaling involving phospholipase C and intracellular calcium stores. Mobilization of intracellular Ca2+ was required for somatostatin induced inhibition of photoreceptor L-VGCCs, suggesting that somatostatin plays an important role in the modulation of photoreceptor physiology.

scholarly journals Oxidative stress increases internal calcium stores and reduces a key mitochondrial enzyme

2002 ◽  
Vol 1586 (2) ◽  
pp. 177-189 ◽  
Author(s):  
Gary E. Gibson ◽  
Hui Zhang ◽  
Hui Xu ◽  
Larry C.H. Park ◽  
Thomas M. Jeitner
Keyword(s):  
Oxidative Stress ◽  
Calcium Stores ◽  
Mitochondrial Enzyme ◽  
Internal Calcium

scholarly journals Econazole inhibits thapsigargin-induced platelet calcium influx by mechanisms other than cytochrome P-450 inhibition

1993 ◽  
Vol 295 (2) ◽  
pp. 525-529 ◽  
Author(s):  
J G Vostal ◽  
J C Fratantoni
Keyword(s):  
Plasma Membrane ◽  
Antifungal Agents ◽  
Calcium Influx ◽  
Calcium Stores ◽  
Alternative Mechanism ◽  
Resting Cells ◽  
Calcium Efflux ◽  
Plasma Membrane Permeability ◽  
Cytochrome P 450 ◽  
Internal Calcium

Cytochrome P-450 has been suggested as a mediator of the signal between depleted platelet calcium stores and an increase in plasma membrane permeability to calcium which follows depletion of the stores. This hypothesis is based on the observations that inhibitors of cytochrome P-450, such as the imidazole antifungal agents, also inhibit influx of a calcium surrogate (manganese) into calcium-depleted platelets. We tested the effects of econazole and of a cytochrome P-450 inhibitor, carbon monoxide (CO), on thapsigargin (TG)-induced platelet 45Ca2+ influx. TG specifically depletes internal calcium stores and activates store-regulated calcium influx. Econazole blocked 45Ca2+ influx when it was added before TG (IC50 11 microM). Econazole at a concentration (20 microM) that inhibited 83% of TG-induced calcium influx was not inhibitory to TG-induced calcium efflux from 45Ca(2+)-loaded platelets, and did not affect calcium fluxes in resting platelets. This econazole concentration was also inhibitory to calcium influx even when it was added after the stores had been calcium-depleted by EGTA and TG for 15 min and the signal to increase calcium influx had already been generated. Inhibition of cytochrome P-450 with CO bubbled through platelet suspensions did not change calcium influx in resting cells and potentiated TG-induced calcium influx (160% of control calcium accumulation at 20 min). This effect appeared to be concentration-dependent, such that a 5 min exposure to CO produced a greater influx potentiation than a 3 min exposure. These observations indicate that (1) cytochrome P-450 does not mediate store-regulated calcium influx, and (2) econazole probably inhibits store-regulated calcium influx by an alternative mechanism, such as interaction with plasma membrane calcium channels.

scholarly journals The Knockout for G Protein-Coupled Receptor-Like PfSR25 Increases the Susceptibility of Malaria Parasites to the Antimalarials Lumefantrine and Piperaquine but Not to Medicine for Malaria Venture Compounds

2021 ◽  
Vol 12 ◽  
Author(s):  
Benedito M. Santos ◽  
Bárbara K. M. Dias ◽  
Myna Nakabashi ◽  
Celia R. S. Garcia
Keyword(s):  
G Protein ◽  
Calcium Entry ◽  
G Protein Coupled Receptor ◽  
Intracellular Calcium Signaling ◽  
Store Operated Calcium Entry ◽  
G Protein Coupled ◽  
Internal Calcium ◽  
Shed Light ◽  
Antimalarial Compounds

Previously we have reported that the G protein-coupled receptor (GPCR)-like PfSR25 in Plasmodium falciparum is a potassium (K+) sensor linked to intracellular calcium signaling and that knockout parasites (PfSR25-) are more susceptible to oxidative stress and antimalarial compounds. Here, we explore the potential role of PfSR25 in susceptibility to the antimalarial compounds atovaquone, chloroquine, dihydroartemisinin, lumefantrine, mefloquine, piperaquine, primaquine, and pyrimethamine and the Medicine for Malaria Venture (MMV) compounds previously described to act on egress/invasion (MMV006429, MMV396715, MMV019127, MMV665874, MMV665878, MMV665785, and MMV66583) through comparative assays with PfSR25- and 3D7 parasite strains, using flow cytometry assays. The IC50 and IC90 results show that lumefantrine and piperaquine have greater activity on the PfSR25- parasite strain when compared to 3D7. For MMV compounds, we found no differences between the strains except for the compound MMV665831, which we used to investigate the store-operated calcium entry (SOCE) mechanism. The results suggest that PfSR25 may be involved in the mechanism of action of the antimalarials lumefantrine and piperaquine. Our data clearly show that MMV665831 does not affect calcium entry in parasites after we depleted their internal calcium pools with thapsigargin. The results demonstrated here shed light on new possibilities on the antimalarial mechanism, bringing evidence of the involvement of the GPCR-like PfSR25.

ATP regulates calcium leak from agonist‐sensitive internal calcium stores

1996 ◽  
Vol 10 (2) ◽  
pp. 302-308 ◽  
Author(s):  
Aldebaran M. Hofer ◽  
Silvana Curci ◽  
Terry E. Machen ◽  
Irene Schulz
Keyword(s):  
Calcium Stores ◽  
Internal Calcium

scholarly journals Activation of the Novel Estrogen Receptor G Protein-Coupled Receptor 30 (GPR30) at the Plasma Membrane

Endocrinology ◽  
2007 ◽  
Vol 148 (7) ◽  
pp. 3236-3245 ◽  
Author(s):  
E. Filardo ◽  
J. Quinn ◽  
Y. Pang ◽  
C. Graeber ◽  
S. Shaw ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
G Protein ◽  
Intracellular Camp ◽  
Calcium Stores ◽  
G Protein Coupled Receptor ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
G Protein Coupled

G protein-coupled receptor 30 (GPR30), a seven-transmembrane receptor (7TMR), is associated with rapid estrogen-dependent, G protein signaling and specific estrogen binding. At present, the subcellular site of GPR30 action is unclear. Previous studies using antibodies and fluorochrome-labeled estradiol (E2) have failed to detect GPR30 on the cell surface, suggesting that GPR30 may function uniquely among 7TMRs as an intracellular receptor. Here, we show that detectable expression of GPR30 on the surface of transfected HEK-293 cells can be selected by fluorescence-activated cell sorting. Expression of GPR30 on the cell surface was confirmed by confocal microscopy using the lectin concanavalin A as a plasma membrane marker. Stimulation of GPR30-expressing HEK-293 cells with 17β-E2 caused sequestration of GPR30 from the cell surface and resulted in its codistribution with clathrin and mobilization of intracellular calcium stores. Evidence that GPR30 signals from the cell surface was obtained from experiments demonstrating that the cell-impermeable E2-protein conjugates E2-BSA and E2-horseradish peroxidase promote GPR30-dependent elevation of intracellular cAMP concentrations. Subcellular fractionation studies further support the plasma membrane as a site of GPR30 action with specific [3H]17β-E2 binding and G protein activation associated with plasma membrane but not microsomal, or other fractions, prepared from HEK-293 or SKBR3 breast cancer cells. These results suggest that GPR30, like other 7TMRs, functions as a plasma membrane receptor.

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