Calcium Signaling (calcium + signaling)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


Ethanol-Induced Cephalic Apoptosis Requires Phospholipase C-Dependent Intracellular Calcium Signaling

ALCOHOLISM, Issue 3 2003
Katherine A. Debelak-Kragtorp
Background: Although the ability of ethanol to elicit neural crest cell apoptosis is well documented, the initial target of ethanol in these cells, and the biochemical pathway leading to their apoptosis, have yet to be determined. Recent work in preimplantation mouse embryos demonstrates that ethanol induces a phospholipase-C (PLC)-dependent calcium transient that mediates ethanol's effects. We tested whether a similar effect on calcium and PLC is involved in ethanol-induced neural crest apoptosis. Methods: Chicken embryos were collected and loaded with Fluo-3-AM to assess the effects of ethanol on intracellular calcium levels. Pharmacological agents were used to determine the sources and mechanism of intracellular calcium increases. In separate experiments, embryos were treated in ovo with pharmacological modulators of calcium signaling prior to ethanol exposure, and resulting levels of cell death were assessed by using the vital dye acridine orange. Results: Ethanol exposure caused a localized increase in intracellular calcium levels in embryonic neural folds within 15 sec of ethanol exposure. Ethanol-induced apoptosis was specifically blocked by chelation of intracellular calcium before ethanol exposure. Pretreatment with the PLC inhibitor U73122 blocked ethanol-induced apoptosis as well as the intracellular calcium transient. Depletion of extracellular calcium resulted in a partial block of ethanol-induced apoptosis. Conclusions: Ethanol exposure alters calcium signaling within the neurulation-stage chicken embryo in a PLC-dependent manner. Increases in intracellular calcium and PLC activity are necessary for ethanol's induction of apoptosis within cephalic populations. These effects likely represent an early and crucial event in the pathway leading to ethanol-induced cell death. [source]


Monocyte-Induced Endothelial Calcium Signaling Mediates Early Xenogeneic Endothelial Activation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2005
Mark D. Peterson
Hallmarks of delayed xenograft rejection include monocyte infiltration, endothelial cell activation and disruption of the endothelial barrier. The monocyte is an important initiator of this type of rejection because monocytes accumulate within hours after xenografting and prior monocyte depletion suppresses the development of this type of rejection. However, the mechanisms that mediate monocyte-induced xenograft injury are unclear at present. Here we report that human monocytes activate xenogeneic endothelial cells through calcium signals. Monocyte contact with porcine but not human endothelium leads to an endothelial calcium transient mediated via a G-protein-coupled receptor (GPCR) that results in up-regulation of porcine VCAM-1 and E-selectin. Although human monocyte adhesion was greater to porcine than to human endothelium, especially when studied under laminar flow, blockade of the xeno-specific endothelial calcium signals did not reduce adhesion of human monocytes to porcine endothelium. Human monocyte contact to porcine endothelium also resulted in reorganization of the F-actin cytoskeleton with a concomitant increase in endothelial monolayer permeability. In contrast to the effect on adhesion, these changes appear to be regulated through endothelial calcium signals. Taken together, these data suggest that human monocytes are capable of activating xenogeneic endothelial cells through calcium transients, as well as other distinct pathways. [source]


Information processing and transmission in glia: Calcium signaling and transmitter release

GLIA, Issue 7 2006
Joachim W. Deitmer
No abstract is available for this article. [source]


Inhibition of Rac1 decreases the severity of pancreatitis and pancreatitis-associated lung injury in mice

EXPERIMENTAL PHYSIOLOGY, Issue 10 2008
Marcelo G. Binker
Pancreatitis is a disease with high morbidity and mortality. In vitro experiments on pancreatic acini showed that supramaximal but not submaximal cholecystokinin (CCK) stimulation induces effects in the acinar cell that can be correlated with acinar morphological changes observed in the in vivo experimental model of cerulein-induced pancreatitis. The GTPase Rac1 was previously reported to be involved in CCK-evoked amylase release from pancreatic acinar cells. Here, we demonstrate that pretreatment with the Rac1 inhibitor NSC23766 (100 ,m, 2 h) effectively blocked Rac1 translocation and activation in CCK-stimulated pancreatic acini, without affecting activation of its closely related GTPase, RhoA. This specific Rac1 inhibition decreased supramaximal (10 nM) CCK-stimulated acinar amylase release (27.% reduction), which seems to be connected to the reduction observed in serum amylase (46.6% reduction) and lipase levels (46.1% reduction) from cerulein-treated mice receiving NSC23766 (100 nmol h,1). The lack of Rac1 activation also reduced formation of reactive oxygen species (ROS; 20.8% reduction) and lactate dehydrogenase release (LDH; 24.3% reduction), but did not alter calcium signaling or trypsinogen activation in 10 nM CCK-stimulated acini. In the in vivo model, the cerulein-treated mice receiving NSC23766 also presented a decrease in both pancreatic and lung histopathological scores (reduction in oedema, 32.4 and 66.4%; haemorrhage, 48.3 and 60.2%; and leukocyte infiltrate, 53.5 and 43.6%, respectively; reduction in pancreatic necrosis, 65.6%) and inflammatory parameters [reduction in myeloperoxidase, 52.2 and 38.9%; nuclear factor ,B (p65), 61.3 and 48.6%; and nuclear factor ,B (p50), 46.9 and 44.9%, respectively], together with lower serum levels for inflammatory (TNF-,, 40.4% reduction) and cellular damage metabolites (LDH, 52.7% reduction). Collectively, these results suggest that pharmacological Rac1 inhibition ameliorates the severity of pancreatitis and pancreatitis-associated lung injury through the reduction of pancreatic acinar damage induced by pathological digestive enzyme secretion and overproduction of ROS. [source]


Carbonyl cyanide m -chlorophenylhydrazone induced calcium signaling and activation of plasma membrane H+ -ATPase in the yeast Saccharomyces cerevisiae

FEMS YEAST RESEARCH, Issue 4 2008
Michele B.P. Pereira
Abstract The plasma membrane H+ -ATPase from Saccharomyces cerevisiae is an enzyme that plays a very important role in the yeast physiology. The addition of protonophores, such as 2,4-dinitrophenol (DNP) and carbonyl cyanide m -chlorophenylhydrazone (CCCP), also triggers a clear in vivo activation of this enzyme. Here, we demonstrate that CCCP-induced activation of the plasma membrane H+ -ATPase shares some similarities with the sugar-induced activation of the enzyme. Phospholipase C and protein kinase C activities are essential for this activation process while Gpa2p, a G protein involved in the glucose-induced activation of the ATPase, is not required. CCCP also induces a phospholipase C-dependent increase in intracellular calcium. Moreover, we show that the availability of extracellular calcium is required for CCCP stimulation of H+ -ATPase, suggesting a possible connection between calcium signaling and activation of ATPase. [source]


Calcium signaling in invertebrate glial cells

GLIA, Issue 7 2006
Christian Lohr
Abstract Calcium signaling studies in invertebrate glial cells have been performed mainly in the nervous systems of the medicinal leech (Hirudo medicinalis) and the sphinx moth Manduca sexta. The main advantages of studing glial cells in invertebrate nervous systems are the large size of invertebrate glial cells and their easy accessibility for optical and electrophysiological recordings. Glial cells in both insects and annelids express voltage-gated calcium channels and, in the case of leech glial cells, calcium-permeable neurotransmitter receptors, which allow calcium influx as one major source for cytosolic calcium transients. Calcium release from intracellular stores can be induced by metabotropic receptor activation in leech glial cells, but appears to play a minor role in calcium signaling. In glial cells of the antennal lobe of Manduca, voltage-gated calcium signaling changes during postembryonic development and is essential for the migration of the glial cells, a key step in axon guidance and in stabilization of the glomerular structures that are characteristic of primary olfactory centers. © 2006 Wiley-Liss, Inc. [source]


Blockage of voltage-gated calcium signaling impairs migration of glial cells in vivo

GLIA, Issue 3 2005
Christian Lohr
Abstract Migration of glial cells is an essential step in the development of the antennal lobe, the primary olfactory center of insects, to establish well-defined borders between olfactory glomeruli required for odor discrimination. In the present study, we used two-photon microscopy to visualize calcium signaling in developing antennal lobe glial cells of the sphinx moth Manduca sexta. We found a correlation between the upregulation of functional voltage-gated calcium channels and the onset of glial cell migration. In addition, glial cells migrating into the center of the antennal lobe express larger voltage-gated calcium transients than glial cells that remain at the periphery. Migration behavior and calcium signaling of glial cells in vivo were manipulated either by deafferentation, by injection of the calcium channel blockers diltiazem, verapamil, and flunarizine, or by injection of the calcium chelators BAPTA-AM and Fluo-4-AM. In deafferented antennal lobes, glial cells failed to express functional voltage-gated calcium channels and did not migrate. Calcium channel blockage or reducing glial calcium signals by calcium chelators prevented glial cell migration and resulted in antennal lobes lacking glial borders around glomeruli, indicating that voltage-gated calcium signaling is required for the migration of antennal lobe glial cells and the development of mature olfactory glomeruli. © 2005 Wiley-Liss, Inc. [source]


Na,K-ATPase ,2 inhibition alters calcium responses in optic nerve astrocytes

GLIA, Issue 3 2004
April K. Hartford
Abstract Experiments were conducted to test the effect of 1 ,M ouabain, an Na,K-ATPase inhibitor, on capacitative calcium entry (CCE) and calcium responses elicited by ATP in rat optic nerve astrocytes. In the rat, 1 ,M ouabain is sufficient to inhibit the ,2 Na,K-ATPase, but not the ,1. Immortalized astrocytes derived from Na,K-ATPase ,2 homozygous knockout (KO) mice and wild-type (WT) littermates were also used. Cytosolic calcium and sodium concentrations were measured using Fura-2 and SBFI, respectively. The magnitude of the increase in cytosolic calcium concentration during CCE was significantly greater in rat astrocytes exposed to 1 ,M ouabain. To measure calcium release from stores, cells were exposed to ATP in the absence of extracellular calcium. In astrocytes exposed to 1 ,M ouabain, a significantly greater calcium response to ATP was observed. 1 ,M ouabain was shown to inhibit ATP hydrolysis in membrane material containing Na,K-ATPase ,2 and ,1 isoforms (rat muscle) but not in membranes containing only Na,K-ATPase ,1 (rat kidney). In intact astrocytes, 1 ,M ouabain did not alter the cell-wide cytosolic sodium concentration. In mouse Na,K-ATPase ,2 KO astrocytes, the calcium increase during CCE was significantly higher than in WT cells, as was the magnitude of the calcium response to ATP. In KO astrocytes, but not WT, the cytosolic calcium increase during CCE was insensitive to 1 ,M ouabain. Taken together, the results suggest that selective inhibition of the Na,K-ATPase ,2 isoform has the potential to change calcium signaling and CCE. © 2003 Wiley-Liss, Inc. [source]


Changes in the expression of plasma membrane calcium extrusion systems during the maturation of hippocampal neurons

HIPPOCAMPUS, Issue 1 2006
Sertac N. Kip
Abstract Spatial and temporal control of intracellular calcium signaling is essential for neuronal development and function. The termination of local Ca2+ signaling and the maintenance of basal Ca2+ levels require specific extrusion systems in the plasma membrane. In rat hippocampal neurons (HNs) developing in vitro, transcripts for all isoforms of the plasma membrane Ca2+ pump and the Na/Ca2+ exchanger, and the major nonphotoreceptor Na+/Ca2+,K+ exchangers (NCKX) were strongly upregulated during the second week in culture. Upregulation of plasma membrane calcium ATPases (PMCAs)1, 3, and 4 mRNA coincided with a splice shift from the ubiquitous b-type to the neuron-specific a-type with altered calmodulin regulation. Expression of all PMCA isoforms increased over 5-fold during the first 2 weeks. PMCA immunoreactivity was initially concentrated in the soma and growth cones of developing HNs. As the cells matured, PMCAs concentrated in the dendritic membrane and often colocalized with actin-rich dendritic spines in mature neurons. In the developing rat hippocampal CA1 region, immunohistochemistry confirmed the upregulation of all PMCAs and showed that by the end of the second postnatal week, PMCAs1, 2, and 3 were concentrated in the neuropil, with less intense staining of cell bodies in the pyramidal layer. PMCA4 staining was restricted to a few cells showing intense labeling of the cell periphery and neurites. These results establish that all major Ca2+ extrusion systems are strongly upregulated in HNs during the first 2 weeks of postnatal development. The overall increase in Ca2+ extrusion systems is accompanied by changes in the expression and cellular localization of different isoforms of the Ca2+ pumps and exchangers. The accumulation of PMCAs in dendrites and dendritic spines coincides with the functional maturation in these neurons, suggesting the importance of the proper spatial organization of Ca2+ extrusion systems for synaptic function and development. © 2005 Wiley-Liss, Inc. [source]


Involvement of calcium in the differential induction of heat shock protein 70 by heat shock protein 90 inhibitors, geldanamycin and radicicol, in human non-small cell lung cancer H460 cells

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2006
Yuo-Sheng Chang
Abstract Both geldanamycin (GA) and radicicol (RA) are HSP90 binding agents that possess antitumour activities. Although the in vitro data indicated that the inhibitory constant of RA is much bigger than that of GA, the in vivo data on drug efficacy might reveal different results. We have recently shown that treatment with GA induces a heat-shock response and that calcium mobilization may be involved in the process. By using induction of HSP70 as the endpoint assay, we found changes in upstream signaling mediators, including HSF1 and calcium mobilization, as well as possible involvement of protein kinase in human non-small cell lung cancer H460 cells treated with GA and RA. Our results demonstrated that calcium mobilization, a calcium dependent and H7-sensitive protein kinase, along with HSF1 activation by phosphorylation, are all involved in the HSP70 induction process triggered by the drugs. However, only GA, but not RA, can provoke a rapid calcium mobilization and thereby result in an instant induction of HSP70. Furthermore, the rapid calcium influx, followed by instant HSP induction, could be achieved in GA- or RA-treated cells placed in a medium containing excessive calcium while the response was completely abolished in cells depleted of calcium. Taken together, our findings suggest that differential calcium signaling may account for the differential induction of HSP and the action of GA and RA. J. Cell. Biochem. © 2005 Wiley-Liss, Inc. [source]


Suppressive role of endogenous regucalcin in the enhancement of protein kinase activity with proliferation of cloned rat hepatoma cells (H4-II-E)

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue S36 2001
Shyuichiroh Inagaki
Abstract The role of endogenous regucalcin, which is a regulatory protein in calcium signaling, in the regulation of protein kinase activity in the proliferation of the cloned rat hepatoma cells (H4-II-E) was investigated. Hepatoma cells were cultured for 6,72,h in the presence of fetal bovine serum (FBS; 1 or 10%). The number of cells and protein kinase activity in the 5500,g supernatant of cell homogenate was significantly increased 24 and 48,h after the culture with FBS (1 or 10%); the culture with 10% FBS was potent effect as compared with that of 1% FBS. FBS (10%)-increased protein kinase activity preceded a significant elevation of cell number of 6,h after culture. Serum stimulation-induced increase in protein kinase activity was significantly decreased in the presence of trifluoperazine (50,,M), staurosporine (10,6,M) or genistein (10,5,M) in the enzyme reaction mixture. The presence of anti-regucalcin monoclonal antibody (40 or 80,ng/ml) in the reaction mixture caused a significant increase in protein kinase activity in the cells cultured with FBS (1 or 10%). This increase was completely blocked by addition of regucalcin (10,6,M), which can reveal an inhibitory effect on protein kinase activity. Moreover, the effect of antibody in increasing protein kinase activity was significantly inhibited in the presence of trifluoperazine, staurosporine, or genistein, indicating that endogenous regucalcin has an inhibitory effect on Ca2+/calmodulin-dependent protein kinase, protein kinase C, and protein tyrosine kinase. The present study suggests that endogenous regucalcin plays a suppressive role in the enhancement of various protein kinase activities associated with a proliferation of the cloned rat hepatoma cells (H4-II-E). J. Cell. Biochem. 36: 12-18, 2001. © 2001 Wiley-Liss. Inc. [source]


Effect of selenium-supplement on the calcium signaling in human endothelial cells,

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2005
Yi Zheng
Intracellular Ca2+ signaling controls many cellular functions. Understanding its regulation by selenoproteins is essential for understanding the role of selenoproteins in regulating cell functions. The activity of thioredoxin reductase (TrxR), thioredoxin (Trx) content, and the activity of glutathione peroxidase (GPx) in the human endothelial cells cultured in selenium-supplemented medium (refer as Se+ cells) was found 70%, 40%, and 20% higher, respectively than those in the cells cultured in normal medium (refer as Se0 cells). The intracellular Ca2+ signaling initiated by inositol 1,4,5-trisphosphate (IP3), histamine, thapsigargin (TG), carbonyl cyanide p -(tri-fluoromethoxy) phenyl-hydrazone (FCCP), and cyclosporin A (CsA) was investigated in both Se+ and Se0 cells. It was interestingly found that the higher activity of selenoproteins reduced the sensitivity of IP3 receptor to the IP3 -triggered Ca2+ release from intracellular stores, but enhanced activation of the receptor-coupled phospholipase C in histamine-stimulated Se+ cells by showing much more generation of IP3 and higher elevation of cytosolic Ca2+. The higher selenoprotein activity also reduced susceptibility of the uniporter to the mitochondrial uncoupler, susceptibility of the permeability transition pore (PTP) to its inhibitor, and the vulnerability of endoplasmic reticulum (ER) Ca2+ -ATPase to its inhibitor in selenium-supplementing cells. The results suggest that cell calcium signaling is subjected to thiol-redox regulation by selenoproteins. © 2005 Wiley-Liss, Inc. [source]


Ethanol-Induced Cephalic Apoptosis Requires Phospholipase C-Dependent Intracellular Calcium Signaling

ALCOHOLISM, Issue 3 2003
Katherine A. Debelak-Kragtorp
Background: Although the ability of ethanol to elicit neural crest cell apoptosis is well documented, the initial target of ethanol in these cells, and the biochemical pathway leading to their apoptosis, have yet to be determined. Recent work in preimplantation mouse embryos demonstrates that ethanol induces a phospholipase-C (PLC)-dependent calcium transient that mediates ethanol's effects. We tested whether a similar effect on calcium and PLC is involved in ethanol-induced neural crest apoptosis. Methods: Chicken embryos were collected and loaded with Fluo-3-AM to assess the effects of ethanol on intracellular calcium levels. Pharmacological agents were used to determine the sources and mechanism of intracellular calcium increases. In separate experiments, embryos were treated in ovo with pharmacological modulators of calcium signaling prior to ethanol exposure, and resulting levels of cell death were assessed by using the vital dye acridine orange. Results: Ethanol exposure caused a localized increase in intracellular calcium levels in embryonic neural folds within 15 sec of ethanol exposure. Ethanol-induced apoptosis was specifically blocked by chelation of intracellular calcium before ethanol exposure. Pretreatment with the PLC inhibitor U73122 blocked ethanol-induced apoptosis as well as the intracellular calcium transient. Depletion of extracellular calcium resulted in a partial block of ethanol-induced apoptosis. Conclusions: Ethanol exposure alters calcium signaling within the neurulation-stage chicken embryo in a PLC-dependent manner. Increases in intracellular calcium and PLC activity are necessary for ethanol's induction of apoptosis within cephalic populations. These effects likely represent an early and crucial event in the pathway leading to ethanol-induced cell death. [source]


Calcium signaling leads to mitochondrial depolarization in impact-induced chondrocyte death in equine articular cartilage explants

ARTHRITIS & RHEUMATISM, Issue 7 2007
C. A. M. Huser
Objective Chondrocyte apoptosis is an important factor in the progression of osteoarthritis. This study aimed to elucidate the mechanisms involved upstream of caspase 9 activation and, in particular, calcium signaling and mitochondrial depolarization. Methods Articular cartilage explants obtained from healthy horses were subjected to a single impact load (500-gm weight dropped from a height of 50 mm) and cultured in vitro for up to 48 hours. Chondrocyte death was quantified by the TUNEL method. Release of proteoglycans was determined by the dimethylmethylene blue assay. Weight change was measured, and mitochondrial depolarization was determined using JC-1 staining. To assess the role of calcium signaling in impact-induced chondrocyte death, explants were preincubated in culture medium containing various concentrations of calcium. Inhibitors were used to assess the role of individual signaling components in impact-induced chondrocyte death. Results Calcium quenching, inhibitors of calpains, calcium/calmodulin-regulated kinase II (CaMKII), and mitochondrial depolarization reduced impact-induced chondrocyte death after 48 hours in culture. Transient mitochondrial depolarization was observed 3,6 hours following a single impact load. Mitochondrial depolarization was prevented by calcium quenching, inhibitors of calpain, CaMKII, permeability transition pore formation, ryanodine receptor, and the mitochondrial uniport transporter. Cathepsin B did not appear to be involved in impact-induced chondrocyte death. The calpain inhibitor prevented proteoglycan loss, but the percentage weight gain and proteoglycan loss were unaffected by all treatments used. Conclusion Following a single impact load, calcium is released from the endoplasmic reticulum via the ryanodine receptor and is taken up by the mitochondria via the uniport transporter, causing mitochondrial depolarization and caspase 9 activation. In addition, calpains and CaMKII play important roles in causing mitochondrial depolarization. [source]


How to tweak a beak: molecular techniques for studying the evolution of size and shape in Darwin's finches and other birds

BIOESSAYS, Issue 1 2007
Richard A. Schneider
A flurry of technological advances in molecular, cellular and developmental biology during the past decade has provided a clearer understanding of mechanisms underlying phenotypic diversification. Building upon such momentum, a recent paper tackles one of the foremost topics in evolution, that is the origin of species-specific beak morphology in Darwin's finches.1 Previous work involving both domesticated and wild birds implicated a well-known signaling pathway (i.e. bone morphogenetic proteins) and one population of progenitor cells in particular (i.e. cranial neural crest), as primary factors for establishing beak size and shape. But these results were limited in their ability to explain fully the morphogenetic bases of patterned outgrowth. So in a quest to identify novel genes whose expression correlated with differences in beak anatomy among Darwin's finches, a DNA microarray approach was undertaken using tissues harvested from the Galápagos Islands. The results are striking and point to a protein called calmodulin, which is a mediator of cellular calcium signaling, as a key determinant of beak length. BioEssays 29: 1,6, 2007. © 2006 Wiley Periodicals, Inc. [source]


Fibroblast response to interstitial flow: A state-of-the-art review

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010
Liu Dan
Abstract Interstitial flow (IF) modulates both the biochemical and biophysical cues surrounding cells. It represents a very important regulating mechanism for cell/tissue function and has been commonly utilized in tissue engineering (TE). This article discusses the possible regulating mechanisms of IF on fibroblasts, the various fibroblast responses to IF, the current challenges in understanding the IF,fibroblast relationship and the application of IF for fibroblast involved TE. In particular, IF can affect fibroblast growth at both intracellular (e.g., calcium signaling, protein/proteinase secretion) and cellular (e.g., autocrine/paracrine signaling, proliferation, differentiation, alignment, adhesion, migration) levels. One major challenge for understanding IF,fibroblast interaction has been the determination of the flow and cell growth condition at microlevel especially in a three-dimensional environment. To utilize IF and optimize the fluidic environment for TE, several influencing factors in the system including perfusate composition, flow profile, nutrient supply, signaling molecule effect, scaffold property, and fibroblast type should be considered. Biotechnol. Bioeng. 2010;107: 1,10. © 2010 Wiley Periodicals, Inc. [source]