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329 records returned

Burst discharges in neurons of the thalamic reticular nucleus are shaped by calcium-induced calcium release.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The nucleus reticularis thalami (NRT) is a layer of inhibitory neurons that surrounds the dorsal thalamus. It appears to be the 'pacemaker' of certain forms of slow oscillations in the thalamus and was proposed to be a key determinant of the internal attentional searchlight as well as the origin of hypersynchronous activity during absence seizures. Neurons of the NRT exhibit a transient depolarization termed low threshold spike (LTS) following sustained hyperpolarization. This is caused by the activation of low-voltage-activated Ca(2+) channels (LVACC). Although the role of these channels in thalamocortical oscillation...
Source: Cell Calcium - November 12, 2009 Category: Cytology Authors: Coulon P, Herr D, Kanyshkova T, Meuth P, Budde T, Pape HC Tags: Cell Calcium Source Type: journals

Altered sarcoplasmic reticulum calcium transport in the presence of the heavy metal chelator TPEN.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)-ethylenediamine) is a membrane-permeable heavy-metal ion chelator with a dissociation constant for Ca(2+) comparable to the Ca(2+) concentration ([Ca(2+)]) within the intracellular Ca(2+) stores. It has been used as modulator of intracellular heavy metals and of free intraluminal [Ca(2+)], without influencing the cytosolic [Ca(2+)] that falls in the nanomolar range. In our previous studies, we gave evidence that TPEN modifies the Ca(2+) homeostasis of striated muscle independent of this buffering ability. Here we describe the direct interaction of TPEN with the ryanodine recept...
Source: Cell Calcium - November 7, 2009 Category: Cytology Authors: Sztretye M, Almássy J, Deli T, Szentesi P, Jung C, Dienes B, Simut CA, Niggli E, Jona I, Csernoch L Tags: Cell Calcium Source Type: journals

Molecular determinants of non-competitive antagonist binding to the mouse GPRC6A receptor.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
GPRC6A displays high sequence homology to the Ca(2+)-sensing receptor (CaSR). Here we report that the calcimimetic Calindol and the calcilytic NPS2143 antagonize increases in inositol phosphate elicited by l-ornithine-induced activation of mouse GPRC6A after transient coexpression with Galpha(qG66D) in HEK293 cells. The calcilytic Calhex 231 did not modulate this response. A three-dimensional model of the GPRC6A seven transmembrane domains (TMs) was constructed. It was used to identify seven residues strictly conserved within the CaSR and GPRC6A allosteric binding pockets, and previously demonstrated to interact with c...
Source: Cell Calcium - October 14, 2009 Category: Cytology Authors: Faure H, Gorojankina T, Rice N, Dauban P, Dodd RH, Bräuner-Osborne H, Rognan D, Ruat M Tags: Cell Calcium Source Type: journals

The sarcoplasmic reticulum Ca(2+) store arrangement in vascular smooth muscle.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study addresses whether the SR Ca(2+) store is a single continuous interconnected network or multiple separate Ca(2+) pools in single vascular myocytes. To do this, the consequences of depletion of the SR in small restricted regions on the Ca(2+) available throughout the store was examined using localized photolysis of caged-IP(3) and focal application of ryanodine in guinea-pig voltage-clamped single portal vein myocytes. From one small site on the cell, the entire SR could be depleted via either RyR or IP(3)R. The entire SR could also be refilled from one small site on the cell. The results suggest a single luminall...
Source: Cell Calcium - October 13, 2009 Category: Cytology Authors: Rainbow RD, Macmillan D, McCarron JG Tags: Cell Calcium Source Type: journals

L-type channel inhibition by CB1 cannabinoid receptors is mediated by PTX-sensitive G proteins and cAMP/PKA in GT1-7 hypothalamic neurons.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Using immortalized hypothalamic GT1-7 neurons, which express the CB1 cannabinoid receptor (CB1R) and three Ca(2+) channel types (T, R and L), we found that the CB1R agonist WIN 55,212-2 inhibited the voltage-gated Ca(2+) currents by about 35%. The inhibition by WIN 55,212-2 (10muM) was reversible and prevented by nifedipine (3muM), suggesting a selective action on L-type Ca(2+) channels (LTCCs). WIN 55,212-2 action exhibited all the features of voltage-independent Ca(2+) channel modulation: (1) no changes of the activation kinetics, (2) equal depressive action at all potentials and (3) no facilitation following strong ...
Source: Cell Calcium - October 6, 2009 Category: Cytology Authors: Hoddah H, Marcantoni A, Comunanza V, Carabelli V, Carbone E Tags: Cell Calcium Source Type: journals

The alpha(2)delta subunit augments functional expression and modifies the pharmacology of Ca(V)1.3 L-type channels.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The auxiliary Ca(V)alpha(2)delta-1 subunit is an important component of voltage-gated Ca(2+) (Ca(V)) channel complexes in many tissues and of great interest as a drug target. Nevertheless, its exact role in specific cell functions is still unknown. This is particularly important in the case of the neuronal L-type Ca(V) channels where these proteins play a key role in the secretion of neurotransmitters and hormones, gene expression, and the activation of other ion channels. Therefore, using a combined approach of patch-clamp recordings and molecular biology, we studied the role of the Ca(V)alpha(2)delta-1 subunit on the...
Source: Cell Calcium - September 28, 2009 Category: Cytology Authors: Andrade A, Sandoval A, González-Ramírez R, Lipscombe D, Campbell KP, Felix R Tags: Cell Calcium Source Type: journals

Bestrophin and TMEM16-Ca(2+) activated Cl(-) channels with different functions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the past, a number of candidates have been proposed to form Ca(2+) activated Cl(-) currents, but it is only recently that two families of proteins, the bestrophins and the TMEM16-proteins, recapitulate reliably the properties of Ca(2+) activated Cl(-) currents. Bestrophin 1 is strongly expressed in the retinal pigment epithelium, but also at lower levels in other cell types. Bestrophin 1 may form Ca(2+) activated chloride channels and, at the same time, affect intracellular Ca(2+) signaling. In epithelial cells, bestrophin 1 probably controls receptor mediated Ca(2+) signaling. It may do so by facilitating Ca(2+) re...
Source: Cell Calcium - September 24, 2009 Category: Cytology Authors: Kunzelmann K, Kongsuphol P, Aldehni F, Tian Y, Ousingsawat J, Warth R, Schreiber R Tags: Cell Calcium Source Type: journals

Structural and biophysical determinants of single Ca(V)3.1 and Ca(V)3.2 T-type calcium channel inhibition by N(2)O.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We investigated the biophysical mechanism of inhibition of recombinant T-type calcium channels Ca(V)3.1 and Ca(V)3.2 by nitrous oxide (N(2)O). To identify functionally important channel structures, chimeras with reciprocal exchange of the N-terminal domains I and II and C-terminal domains III and IV were examined. In whole-cell recordings N(2)O significantly inhibited Ca(V)3.2, and - less pronounced - Ca(V)3.1. A Ca(V)3.2-prevalent inhibition of peak currents was also detected in cell-attached multi-channel patches. In cell-attached patches containing </=3 channels N(2)O reduced average peak current of Ca(V)3.2 by d...
Source: Cell Calcium - September 24, 2009 Category: Cytology Authors: Bartels P, Behnke K, Michels G, Groner F, Schneider T, Henry M, Barrett PQ, Kang HW, Lee JH, Wiesen MH, Matthes J, Herzig S Tags: Cell Calcium Source Type: journals

Calcineurin activation by slow calcium release from intracellular stores suppresses protein kinase C regulation of L-type calcium channels in L6 cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study is the first to demonstrate that the regulation of L-type Ca(2+) channels in a myocyte model involves a balance between the differential Ca(2+) sensitivities and opposing actions of PKC and calcineurin. PMID: 19758695 [PubMed - as supplied by publisher] (Source: Cell Calcium)
Source: Cell Calcium - September 13, 2009 Category: Cytology Authors: Turner JD, Thomas AP, Reeves JP, Hantash BM Tags: Cell Calcium Source Type: journals

Extracellular NAD(+) induces a rise in [Ca(2+)](i) in activated human monocytes via engagement of P2Y(1) and P2Y(11) receptors.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Extracellular nicotinamide adenine dinucleotide (NAD(+)) is known to increase the intracellular calcium concentration [Ca(2+)](i) in different cell types and by various mechanisms. Here we show that NAD(+) triggers a transient rise in [Ca(2+)](i) in human monocytes activated with lipopolysaccharide (LPS), which is caused by a release of Ca(2+) from IP(3)-responsive intracellular stores and an influx of extracellular Ca(2+). By the use of P2 receptor-selective agonists and antagonists we demonstrate that P2 receptors play a role in the NAD(+)-induced calcium response in activated monocytes. Of the two subclasses of P2 r...
Source: Cell Calcium - September 9, 2009 Category: Cytology Authors: Klein C, Grahnert A, Abdelrahman A, Müller CE, Hauschildt S Tags: Cell Calcium Source Type: journals

Endoplasmic reticulum Ca(2+) release through ryanodine and IP(3) receptors contributes to neuronal excitotoxicity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we analyzed the contribution of ER-Ca(2+) release through ryanodine (RyR) and IP(3) (IP(3)R) receptors to a neuronal in vitro model of excitotoxicity. NMDA induced a dose-dependent neuronal death, which was significantly decreased by ER-Ca(2+) release inhibitors in cortical neurons as well as in organotypic slices. Furthermore, ryanodine and 2APB, RyR and IP(3)R inhibitors respectively, attenuated NMDA-triggered intracellular Ca(2+) increase and oxidative stress, whereas 2APB reduced mitochondrial membrane depolarization and caspase-3 cleavage. Consistent with ER-Ca(2+) homeostasis disruption, we observed th...
Source: Cell Calcium - September 8, 2009 Category: Cytology Authors: Ruiz A, Matute C, Alberdi E Tags: Cell Calcium Source Type: journals

Recent progress on STIM1 domains controlling Orai activation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ca(2+) entry in non-excitable cells is mainly carried by store-operated channels among which the CRAC channel is best characterized. Its two limiting molecular components are represented by the Ca(2+) sensor protein STIM1 located in the endoplasmic reticulum and Orai1 in the plasma membrane. STIM1 senses a decrease of the Ca(2+) content in internal stores and triggers its accumulation into puncta like structures resulting in coupling to as well as activation of Orai1 channels. The STIM1-Orai coupling process is determined by an interaction via their C-termini. This review highlights recent developments on domains parti...
Source: Cell Calcium - September 2, 2009 Category: Cytology Authors: Schindl R, Muik M, Fahrner M, Derler I, Fritsch R, Bergsmann J, Romanin C Tags: Cell Calcium Source Type: journals

Discrete proteolysis of neuronal calcium sensor-1 (NCS-1) by mu-calpain disrupts calcium binding.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Neuronal calcium sensor-1 (NCS-1) is a high-affinity, low-capacity Ca(2+)-binding protein expressed in many cell types. We previously showed that NCS-1 interacts with inositol 1,4,5-trisphosphate receptor (InsP(3)R) and modulates Ca(2+)-signaling by enhancing InsP3-dependent InsP(3)R channel activity and intracellular Ca(2+) transients. Recently we reported that the chemotherapeutic agent, paclitaxel (taxol) triggers mu-calpain dependent proteolysis of NCS-1, leading to reduced Ca(2+)-signaling within the cell. Degradation of NCS-1 may be critical in the induction of peripheral neuropathy associated with taxol treatmen...
Source: Cell Calcium - September 1, 2009 Category: Cytology Authors: Blachford C, Celić A, Petri ET, Ehrlich BE Tags: Cell Calcium Source Type: journals

Effects of neuropathy on high-voltage-activated Ca(2+) current in sensory neurones.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Voltage-dependent Ca(2+) channels (VDCCs) have emerged as targets to treat neuropathic pain; however, amongst VDCCs, the precise role of the Ca(V)2.3 subtype in nociception remains unproven. Here, we investigate the effects of partial sciatic nerve ligation (PSNL) on Ca(2+) currents in small/medium diameter dorsal root ganglia (DRG) neurones isolated from Ca(V)2.3(-/-) knock-out and wild-type (WT) mice. DRG neurones from Ca(V)2.3(-/-) mice had significantly reduced sensitivity to SNX-482 versus WT mice. DRGs from Ca(V)2.3(-/-) mice also had increased sensitivity to the Ca(V)2.2 VDCC blocker omega-conotoxin. In WT mice,...
Source: Cell Calcium - August 30, 2009 Category: Cytology Authors: Yang L, Stephens GJ Tags: Cell Calcium Source Type: journals

When worlds collide: IP(3) receptors and the ERAD pathway.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
While cell signaling devotees tend to think of the endoplasmic reticulum (ER) as a Ca(2+) store, those who study protein synthesis tend to see it more as site for protein maturation, or even degradation when proteins do not fold properly. These two worldviews collide when inositol 1,4,5-trisphosphate (IP(3)) receptors are activated, since in addition to acting as release channels for stored ER Ca(2+), IP(3) receptors are rapidly destroyed via the ER-associated degradation (ERAD) pathway, a ubiquitination- and proteasome-dependent mechanism that clears the ER of aberrant proteins. Here we review recent studies showing t...
Source: Cell Calcium - August 23, 2009 Category: Cytology Authors: Wojcikiewicz RJ, Pearce MM, Sliter DA, Wang Y Tags: Cell Calcium Source Type: journals

TRPC1 inhibits apoptotic cell degeneration induced by dopaminergic neurotoxin MPTP/MPP(+).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Disturbances in Ca(2+) homeostasis have been implicated in a variety of neuropathological conditions including Parkinson's disease (PD). However, the importance of store-operated Ca(2+) entry (SOCE) channels in PD remains to be investigated. In the present study, we have scrutinized the significance of TRPC1 in 1-methyl-4-phenyl-1,2,3,6-tetrahyrdro-pyridine (MPTP)-induced PD using C57BL/6 animal model and PC12 cell culture model. Both sub-acute and sub-chronic treatments of MPTP significantly reduced TRPC1, and tyrosine hydroxylase levels, but not TRPC3, along with increased neuronal death. Furthermore, MPTP induces mi...
Source: Cell Calcium - August 17, 2009 Category: Cytology Authors: Selvaraj S, Watt JA, Singh BB Tags: Cell Calcium Source Type: journals

Mice carrying a conditional Serca2(flox) allele for the generation of Ca(2+) handling-deficient mouse models.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sarco(endo)plasmic reticulum calcium ATPases (SERCA) are cellular pumps that transport Ca(2+) into the sarcoplasmic reticulum (SR). Serca2 is the most widely expressed gene family member. The very early embryonic lethality of Serca2(null) mouse embryos has precluded further evaluation of loss of Serca2 function in the context of organ physiology. We have generated mice carrying a conditional Serca2(flox) allele which allows disruption of the Serca2 gene in an organ-specific and/or inducible manner. The model was tested by mating Serca2(flox) mice with MLC-2v(wt/Cre) mice and with alphaMHC-Cre transgenic mice. In hetero...
Source: Cell Calcium - August 16, 2009 Category: Cytology Authors: Andersson KB, Finsen AV, Sjåland C, Winer LH, Sjaastad I, Odegaard A, Louch WE, Wang Y, Chen J, Chien KR, Sejersted OM, Christensen G Tags: Cell Calcium Source Type: journals

Dual modulation of CNS voltage-gated calcium channels by cannabinoids: Focus on CB1 receptor-independent effects.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The neuromodulatory effects of cannabinoids in the central nervous system have mainly been associated with G-protein coupled cannabinoid receptor (CB1R) mediated inhibition of voltage-gated calcium channels (VGCCs). Numerous studies show, however, that cannabinoids can also modulate VGCCs independent of CB1R activation. Nevertheless, despite the fact that endocannabinoids have a nearly equal efficacy for direct and CB1R-mediated effects on VGCC, the role of the direct cannabinoid-VGCC interaction has been largely underestimated. In this review, we summarize recent studies on the modulation of different types of VGCCs b...
Source: Cell Calcium - August 11, 2009 Category: Cytology Authors: Lozovaya N, Min R, Tsintsadze V, Burnashev N Tags: Cell Calcium Source Type: journals

Variable luminal sarcoplasmic reticulum Ca(2+) buffer capacity in smooth muscle cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sarcoplasmic reticulum contains the internal Ca(2+) store in smooth muscle cells and its lumen appears to be a continuum that lacks diffusion barriers. Accordingly, the free luminal Ca(2+) level is the same all throughout the SR; however, whether the Ca(2+) buffer capacity is the same in all the SR is unknown. We have estimated indirectly the luminal Ca(2+) buffer capacity of the SR by comparing the reduction in SR Ca(2+) levels with the corresponding increase in [Ca(2+)](i) during activation of either IP(3)Rs with carbachol or RyRs with caffeine, in smooth muscle cells from guinea pig urinary bladder. We have determin...
Source: Cell Calcium - August 10, 2009 Category: Cytology Authors: Dagnino-Acosta A, Guerrero-Hernández A Tags: Cell Calcium Source Type: journals

Calcium signals activated by ghrelin and D-Lys(3)-GHRP-6 ghrelin antagonist in developing dorsal root ganglion glial cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ghrelin is a hormone regulating energy homeostasis via interaction with its receptor, GHSR-1a. Ghrelin activities in dorsal root ganglia (DRG) cells are unknown. Herein we show that ghrelin induces a change of cytosolic calcium concentration in both glia and neurons of embryonic chick DRG. Both RT-PCR and binding studies performed with fluorescent ghrelin in the presence of either unlabeled ghrelin or GHSR-1a antagonist D-Lys(3)-GHRP-6, indicate that DRG cells express GHSR-1a. In glial cells the response is characterized by a rapid transient rise in [Ca(2+)](i) followed by a long lasting rise. The calcium elevation is ...
Source: Cell Calcium - August 5, 2009 Category: Cytology Authors: Erriquez J, Bernascone S, Ciarletta M, Filigheddu N, Graziani A, Distasi C Tags: Cell Calcium Source Type: journals

Ca(2+) regulation of connexin 43 hemichannels in C6 glioma and glial cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Connexin hemichannels have a low open probability under normal conditions but open in response to various stimuli, forming a release pathway for small paracrine messengers. We investigated hemichannel-mediated ATP responses triggered by changes of intracellular Ca(2+) ([Ca(2+)](i)) in Cx43 expressing glioma cells and primary glial cells. The involvement of hemichannels was confirmed with gja1 gene-silencing and exclusion of other release mechanisms. Hemichannel responses were triggered when [Ca(2+)](i) was in the 500nM range but the responses disappeared with larger [Ca(2+)](i) transients. Ca(2+)-triggered responses in...
Source: Cell Calcium - August 2, 2009 Category: Cytology Authors: De Vuyst E, Wang N, Decrock E, De Bock M, Vinken M, Van Moorhem M, Lai C, Culot M, Rogiers V, Cecchelli R, Naus CC, Evans WH, Leybaert L Tags: Cell Calcium Source Type: journals

Metal-controlled interdomain cooperativity in parvalbumins.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conformational behavior of five homologous proteins, parvalbumins (PAs) from northern pike (alpha and beta isoforms), Baltic cod, and rat (alpha and beta isoforms), was studied by scanning calorimetry, circular dichroism, and bis-ANS fluorescence. The mechanism of the temperature-induced denaturation of these proteins depends dramatically on both the peculiarities of their amino acid sequences and on their interaction with metal ions. For example, the pike alpha-PA melting can be described by two successive two-state transitions with mid-temperatures of 90 and 120 degrees C, suggesting the presence of two thermodynamic...
Source: Cell Calcium - July 31, 2009 Category: Cytology Authors: Permyakov SE, Bakunts AG, Permyakova ME, Denesyuk AI, Uversky VN, Permyakov EA Tags: Cell Calcium Source Type: journals

Mitochondrial Ca(2+) uptake is inhibited by a concerted action of p38 MAPK and protein kinase D.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Angiotensin II elicits cytosolic Ca(2+) signal that is transferred into the mitochondria. Previously we found in H295R cells that this signal transfer is enhanced by both the inhibition of p38 MAPK and a novel isoform of PKC [G. Szanda, P. Koncz, A. Rajki, A. Spät, Participation of p38 MAPK and a novel-type protein kinase C in the control of mitochondrial Ca(2+) uptake, Cell Calcium 43 (2008) 250-259]. Now we report that simultaneous activation of these protein kinases (by TNFalpha and PMA+an inhibitor of the conventional PKC isoforms, respectively) attenuates the transfer of cytosolic Ca(2+) signal, elicited by d...
Source: Cell Calcium - July 22, 2009 Category: Cytology Authors: Koncz P, Szanda G, Fülöp L, Rajki A, Spät A Tags: Cell Calcium Source Type: journals

Mitochondria modulate the spatio-temporal properties of intra- and intercellular Ca(2+) signals in cochlear supporting cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the cochlea, cell damage triggers intercellular Ca(2+) waves that propagate through the glial-like supporting cells that surround receptor hair cells. These Ca(2+) waves are thought to convey information about sensory hair cell-damage to the surrounding supporting cells within the cochlear epithelium. Mitochondria are key regulators of cytoplasmic Ca(2+) concentration ([Ca(2+)](cyt)), and yet little is known about their role during the propagation of such intercellular Ca(2+) signalling. Using neonatal rat cochlear explants and fluorescence imaging techniques, we explore how mitochondria modulate supporting cell [Ca...
Source: Cell Calcium - July 21, 2009 Category: Cytology Authors: Mann ZF, Duchen MR, Gale JE Tags: Cell Calcium Source Type: journals

Osmotic induction of calcium accumulation in human embryonic kidney cells detected with a high sensitivity FRET calcium sensor.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Calcium serves as a second messenger in glucose-triggered insulin secretion of pancreatic cells. Less is known about sugar signaling in non-excitable cells. Here, the high sensitivity FRET calcium sensor TN-XXL was used to characterize glucose-induced calcium responses in non-excitable human embryonic kidney HEK293T cells. HEK293T cells responded to perfusion with glucose with a sustained and concentration-dependent increase in cytosolic calcium levels. Sucrose and mannitol triggered comparable calcium responses, suggesting that the increase of the calcium concentration was caused by osmotic effects. HEK293T cells are ...
Source: Cell Calcium - July 20, 2009 Category: Cytology Authors: Hou BH, Takanaga H, Griesbeck O, Frommer WB Tags: Cell Calcium Source Type: journals

Pathways of abnormal stress-induced Ca(2+) influx into dystrophic mdx cardiomyocytes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In Duchenne muscular dystrophy, deficiency of the cytoskeletal protein dystrophin leads to well-described defects in skeletal muscle, but also to dilated cardiomyopathy, accounting for about 20% of the mortality. Mechanisms leading to cardiomyocyte cell death and cardiomyopathy are not well understood. One hypothesis suggests that the lack of dystrophin leads to membrane instability during mechanical stress and to activation of Ca(2+) entry pathways. Using cardiomyocytes isolated from dystrophic mdx mice we dissected the contribution of various putative Ca(2+) influx pathways with pharmacological tools. Cytosolic Ca(2+...
Source: Cell Calcium - July 12, 2009 Category: Cytology Authors: Fanchaouy M, Polakova E, Jung C, Ogrodnik J, Shirokova N, Niggli E Tags: Cell Calcium Source Type: journals

Inhibition of mitochondrial calcium uptake rather than efflux impedes calcium release by inositol-1,4,5-trisphosphate-sensitive receptors.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Mitochondria modulate cellular Ca(2+) signals by accumulating the ion via a uniporter and releasing it via Na(+)- or H(+)-exchange. In smooth muscle, inhibition of mitochondrial Ca(2+) uptake inhibits Ca(2+) release from the sarcoplasmic reticulum (SR) via inositol-1,4,5-trisphosphate-sensitive receptors (IP(3)R). At least two mechanisms may explain this effect. First, localised uptake of Ca(2+) by mitochondria may prevent negative feedback by cytosolic Ca(2+) on IP(3)R activity, or secondly localised provision of Ca(2+) by mitochondrial efflux may maintain IP(3)R function or SR Ca(2+) content. To distinguish between t...
Source: Cell Calcium - July 2, 2009 Category: Cytology Authors: Chalmers S, McCarron JG Tags: Cell Calcium Source Type: journals

Regulation of store-operated Ca(2+) entry in pulmonary artery smooth muscle cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Store-operated Ca(2+) entry (SOCE) is an important mechanism for Ca(2+) influx in smooth muscle cells; however the activation and regulation of this influx pathway are incompletely understood. In the present study we have examined the effect of several protein kinases in regulating SOCE in pulmonary artery smooth muscle cells (PASMCs) of the rat. Inhibition of protein kinase C with chelerythrine (3muM) potentiated SOCE by 47+/-2%, while the tyrosine kinase inhibitors genistein (100muM) and tyrphostin 23 (100muM) caused a significant reduction in SOCE of 55+/-9% and 43+/-7%, respectively. It has been proposed that Ca(2+...
Source: Cell Calcium - June 29, 2009 Category: Cytology Authors: McElroy SP, Drummond RM, Gurney AM Tags: Cell Calcium Source Type: journals

Differences of Ca(2+) handling properties in identified central olfactory neurons of the antennal lobe.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Information processing in neurons depends on highly localized Ca(2+) signals. The spatial and temporal dynamics of these signals are determined by a variety of cellular parameters including the calcium influx, calcium buffering and calcium extrusion. Our long-term goal is to better understand how intracellular Ca(2+) dynamics are controlled and contribute to information processing in defined interneurons of the insect olfactory system. The latter has served as an excellent model to study general mechanisms of olfaction. Using patch-clamp recordings and fast optical imaging in combination with the 'added buffer approach...
Source: Cell Calcium - June 19, 2009 Category: Cytology Authors: Pippow A, Husch A, Pouzat C, Kloppenburg P Tags: Cell Calcium Source Type: journals

Viral calciomics: Interplays between Ca(2+) and virus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ca(2+) is one of the most universal and versatile signaling molecules and is involved in almost every aspect of cellular processes. Viruses are adept at utilizing the universal Ca(2+) signal to create a tailored cellular environment that meets their own demands. This review summarizes most of the known mechanisms by which viruses perturb Ca(2+) homeostasis and utilize Ca(2+) and cellular Ca(2+)-binding proteins to their benefit in their replication cycles. Ca(2+) plays important roles in virion structure formation, virus entry, viral gene expression, posttranslational processing of viral proteins and virion maturation ...
Source: Cell Calcium - June 14, 2009 Category: Cytology Authors: Zhou Y, Frey TK, Yang JJ Tags: Cell Calcium Source Type: journals

Reduction in TRPC4 expression specifically attenuates G-protein coupled receptor-stimulated increases in intracellular calcium in human myometrial cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Canonical transient receptor potential (TRPC) proteins may play a role in regulating changes in intracellular calcium ([Ca(2+)](i)). Human myometrium expresses TRPC4, TRPC1 and TRPC6 mRNAs in greatest relative abundance. Contributions of TRPC4 to increases in [Ca(2+)](i) were assessed in PHM1-41 and primary human uterine smooth muscle (UtSMC) cells using short hairpin RNAs (shRNAs). Based on a reporter assay screen, one shRNA was selected to construct an adenoviral expression vector (TC4sh1). TC4sh1 induced both mRNA and protein TRPC4 knockdown in PHM1-41 cells without affecting expression of other TRPCs. Signal-regula...
Source: Cell Calcium - June 9, 2009 Category: Cytology Authors: Ulloa A, Gonzales AL, Zhong M, Kim YS, Cantlon J, Clay C, Ku CY, Earley S, Sanborn BM Tags: Cell Calcium Source Type: journals

PKC and PLA2: probing the complexities of the calcium network.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present here computational methods which have been developed to conquer such complex data, and how they can be used to make models capable of accurately predicting cellular responses within multiple calcium signaling pathways. We propose that information obtained from network analysis and computational techniques provides a rich source of knowledge which can be directly translated to the laboratory benchtop. PMID: 19345415 [PubMed - in process] (Source: Cell Calcium)
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: van Rossum DB, Patterson RL Tags: Cell Calcium Source Type: journals

Role of endocannabinoids and endovanilloids in Ca2+ signalling.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Endocannabinoids and endovanilloids are, by definition, endogenous agonists at cannabinoid CB(1) or CB(2) receptors and transient receptor potential vanilloid-type-1 (TRPV1) channels, respectively. Due to the several ways through which cannabinoid receptors influence cytosolic Ca(2+) concentrations, and to the fact that TRPV1 activation leads to the gating of cations, including Ca(2+), both endocannabinoids and endovanilloids, taken separately, can strongly influence Ca(2+) signalling. Moreover, CB(1)/CB(2) receptors and TRPV1 channels are often expressed in the same or neighbouring cells, and this can lead to cross-ta...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: De Petrocellis L, Di Marzo V Tags: Cell Calcium Source Type: journals

Regulation of Drosophila TRPC channels by lipid messengers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Drosophila TRPC channels TRP and TRPL are the founding members of the TRP superfamily of ion channels, which are important components of calcium influx pathways in virtually all cells. The activation of these channels in the context of fly phototransduction is one of the few in vivo models for TRPC channel activation and has served as a paradigm for understanding TRPC function. TRP and TRPL are activated by G-protein coupled PIP(2) hydrolysis through a mechanism in which IP(3) receptor mediated calcium release seems dispensable. Recent analysis has provided compelling evidence that one or more PIP(2) generated lipi...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Raghu P, Hardie RC Tags: Cell Calcium Source Type: journals

Role of cardiolipin peroxidation and Ca2+ in mitochondrial dysfunction and disease.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cardiolipin is a unique phospholipid which is almost exclusively located at the level of the inner mitochondrial membrane where it is biosynthesized. This phospholipid is known to be intimately involved in several mitochondrial bioenergetic processes. In addition, cardiolipin also has active roles in several of the mitochondrial-dependent steps of apoptosis and in mitochondrial membrane dynamics. Alterations in cardiolipin structure, content and acyl chains composition have been associated with mitochondrial dysfunction in multiple tissues in several physiopathological conditions, including ischemia/reperfusion, differ...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Paradies G, Petrosillo G, Paradies V, Ruggiero FM Tags: Cell Calcium Source Type: journals

First came the link between phosphoinositides and Ca2+ signalling, and then a deluge of other phosphoinositide functions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article briefly outlines how the roles of these minority membrane lipids in Ca(2+) signalling and then in multifarious other biological processes were recognised during the latter half of the 20th century. PMID: 19371949 [PubMed - in process] (Source: Cell Calcium)
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Michell RH Tags: Cell Calcium Source Type: journals

Phosphoinositide regulation of non-canonical transient receptor potential channels.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Transient receptor potential (TRP) channels are involved in a wide range of physiological processes, and characterized by diverse activation mechanisms. Phosphoinositides, especially phosphatidylinositol 4,5-bisphosphate [PIP(2), or PtdIns(4,5)P(2)] recently emerged as regulators of many TRP channels. Several TRP channels require PIP(2) for activity, and depletion of the lipid inhibits them. For some TRP channels, however, phosphoinositide regulation seems more complex, both activating and inhibitory effects have been reported. This review will discuss phosphoinositide regulation of members of the TRPM (Melastatin), TR...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Rohacs T Tags: Cell Calcium Source Type: journals

Key role of a PtdIns-4,5P2 micro domain in ionic regulation of the mammalian heart Na+/Ca2+ exchanger.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Phosphatidylinositol biphosphate (PtdIns-4,5P(2)) plays a key role in the regulation of the mammalian heart Na(+)/Ca(2+) exchanger (NCX1) by protecting the intracellular Ca(2+) regulatory site against H(+)(i) and (H(+)(i)+Na(+)(i)) synergic inhibition. MgATP and MgATP-gamma-S up-regulation of NCX1 takes place via the production of this phosphoinositide. In microsomes containing PtdIns-4,5P(2) incubated in the absence of MgATP and at normal [Na(+)](i), alkalinization increases the affinity for Ca(2+)(i) to the values seen in the presence of the nucleotide at normal pH; under this condition, addition of MgATP does not in...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Berberián G, Forcato D, Beaugé L Tags: Cell Calcium Source Type: journals

Regulation of Ca2+ entry by inositol lipids in mammalian cells by multiple mechanisms.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Increased phosphoinositide turnover was first identified as an early signal transduction event initiated by cell surface receptors that were linked to calcium signaling. Subsequently, the generation of inositol 1,4,5-trisphosphate by phosphoinositide-specific phospholipase C enzymes was defined as the major link between inositide turnover and the cytosolic Ca(2+) rise in response to external stimulation. However, in the last decades, phosphoinositides have been emerging as major regulatory lipids involved in virtually every membrane-associated signaling process. Phosphoinositides regulate both the activity and the traf...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Balla T Tags: Cell Calcium Source Type: journals

Lipids in Ca2+ signalling--an introduction.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Lipids and lipid-derived metabolites are increasingly recognised as bonafide signalling molecules that regulate many cellular processes. These include the well-established InsP(3), diacylglycerol (DAG), PIP(2), PIP(3) and arachidonic acid (AA), as well as other poly-unsaturated fatty acids (PUFAs), lysophospholipids, sphingolipids, endocannabinoids and endovanilloids. They regulate a plethora of molecules that are involved in Ca(2+) signalling, including various ion channels, pumps and transporters, thereby triggering, modulating and fine-tuning Ca(2+) signals. Although appreciated individually, it seems timely to high...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Hardie RC, Muallem S Tags: Cell Calcium Source Type: journals

Regulation of voltage-gated Ca2+ channels by lipids.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present evidence that phosphatidylinositol 4,5-bisphosphate (PIP(2)), a palmitoylated accessory subunit (beta(2a)) of VGCCs and AA appear to have overlapping sites of action giving rise to complex channel behavior. Their actions converge in a physiologically relevant manner during muscarinic modulation of VGCCs. We speculate that M(1) muscarinic receptors may stimulate multiple lipases to break down the PIP(2) associated with VGCCs and leave PIP(2)'s freed fatty acid tails bound to the channels to confer modulation. This unexpectedly simple scheme gives rise to unanticipated predictions and redirects thinking about lipi...
Source: Cell Calcium - May 31, 2009 Category: Cytology Authors: Roberts-Crowley ML, Mitra-Ganguli T, Liu L, Rittenhouse AR Tags: Cell Calcium Source Type: journals

Calcium-independent phospholipase A(2) participates in KCl-induced calcium sensitization of vascular smooth muscle.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In vascular smooth muscle, KCl not only elevates intracellular free Ca(2+) ([Ca(2+)](i)), myosin light chain kinase activity and tension (T), but also can inhibit myosin light chain phosphatase activity by activation of rhoA kinase (ROCK), resulting in Ca(2+) sensitization (increased T/[Ca(2+)](i) ratio). Precisely how KCl causes ROCK-dependent Ca(2+) sensitization remains to be determined. Using Fura-2-loaded isometric rings of rabbit artery, we found that the Ca(2+)-independent phospholipase A(2) (iPLA(2)) inhibitor, bromoenol lactone (BEL), reduced the KCl-induced tonic but not early phasic phase of T and potentiate...
Source: Cell Calcium - May 29, 2009 Category: Cytology Authors: Ratz PH, Miner AS, Barbour SE Tags: Cell Calcium Source Type: journals

Regulation of inositol 1,4,5-trisphosphate receptor type 1 function during oocyte maturation by MPM-2 phosphorylation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, the recently discovered specific Polo-like kinase (Plk) inhibitor BI2536 was used to investigate the role of Plk1 in this process. BI2536 inactivates Plk1 in oocytes at the early stages of maturation and significantly decreases IP(3)R1 phosphorylation at an MPM-2 epitope at this stage. Moreover, this decrease in Plk1-dependent MPM-2 phosphorylation significantly lowers IP(3)R1 sensitivity. Finally, using in vitro phosphorylation techniques we identified T(2656) as a major Plk1 site on IP(3)R1. We therefore propose that the initial increase in IP(3)R1 sensitivity during oocyte maturation is underpinned by IP(...
Source: Cell Calcium - May 28, 2009 Category: Cytology Authors: Vanderheyden V, Wakai T, Bultynck G, De Smedt H, Parys JB, Fissore RA Tags: Cell Calcium Source Type: journals

Fantastic Ca(2+) "z-waves" fade out quietly.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The first report that high speed Ca(2+) waves travel in a restricted zone around the cell periphery in a clockwise manner and which can only be revealed by very high speed imaging has been quietly retracted. In the original report, a single small region of high Ca(2+) was seen to spin around the cell periphery and around phagosomes formed within phagocytes in a manner unlike anything reported previously. This consequently caused a lot of interest. Several other papers reporting a similar phenomenon in a variety of cells were also published by the same lab and the phenomenon has been included in high profile reviews suc...
Source: Cell Calcium - May 15, 2009 Category: Cytology Authors: Hallett MB, Lebiedz D, Mommer MS, Reble C, Saltmarsh EJ Tags: Cell Calcium Source Type: journals

Store-operated Ca(2+) influx and subplasmalemmal mitochondria.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Calcium depletion of the endoplasmic reticulum (ER) induces oligomerisation, puncta formation and translocation of the ER Ca(2+) sensor proteins, STIM1 and -2 into plasma membrane (PM)-adjacent regions of the ER, where they activate the Orai1, -2 or -3 proteins present in the opposing PM. These proteins form ion channels through which store-operated Ca(2+) influx (SOC) occurs. Calcium ions exert negative feed-back on SOC. Here we examined whether subplasmalemmal mitochondria, which reduce this feed-back by Ca(2+) uptake, are located within or out of the high-Ca(2+) microdomains (HCMDs) formed between the ER and plasmal...
Source: Cell Calcium - May 5, 2009 Category: Cytology Authors: Korzeniowski MK, Szanda G, Balla T, Spät A Tags: Cell Calcium Source Type: journals

Intracellular Ca(2+) stores modulate SOCCs and NMDA receptors via tyrosine kinases in rat hippocampal neurons.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study provides first evidence for tyrosine based phospho-regulation of SOCCs and NMDA signalling in neurons. PMID: 19423160 [PubMed - as supplied by publisher] (Source: Cell Calcium)
Source: Cell Calcium - May 4, 2009 Category: Cytology Authors: Koss DJ, Riedel G, Platt B Tags: Cell Calcium Source Type: journals

Aberrant Ca2+ oscillations in smooth muscle cells from overactive human bladders.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study provides the first evidence that spontaneous, autonomous cellular activity-Ca(2+) and membrane potential oscillations, originates from detrusor smooth muscle in human bladders, mediated by extracellular Ca(2+) influx and intracellular release. Such cellular activity underlies spontaneous muscle contraction and defective Ca(2+) activation contributes to up-regulated contractile activity in overactive bladders. PMID: 19345414 [PubMed - indexed for MEDLINE] (Source: Cell Calcium)
Source: Cell Calcium - April 30, 2009 Category: Cytology Authors: Sui G, Fry CH, Malone-Lee J, Wu C Tags: Cell Calcium Source Type: journals

A comparison of Zn2+- and Ca2+-triggered depolarization of liver mitochondria reveals no evidence of Zn2+-induced permeability transition.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Intracellular Zn(2+) toxicity is associated with mitochondrial dysfunction. Zn(2+) depolarizes mitochondria in assays using isolated organelles as well as cultured cells. Some reports suggest that Zn(2+)-induced depolarization results from the opening of the mitochondrial permeability transition pore (mPTP). For a more detailed analysis of this relationship, we compared Zn(2+)-induced depolarization with the effects of Ca(2+) in single isolated rat liver mitochondria monitored with the potentiometric probe rhodamine 123. Consistent with previous work, we found that relatively low levels of Ca(2+) caused rapid, complete...
Source: Cell Calcium - April 30, 2009 Category: Cytology Authors: Devinney MJ, Malaiyandi LM, Vergun O, DeFranco DB, Hastings TG, Dineley KE Tags: Cell Calcium Source Type: journals

Characterization of somatic Ca2+ clearance mechanisms in young and mature hippocampal granule cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Calcium is a key regulator for expression of genes relevant to survival and maturation of newborn neurons. Mammalian hippocampal dentate gyrus generates new granule cells (GCs) throughout adult life. We identified young and mature GCs in hippocampi of young adult mice according to their electrical properties, and investigated contributions of Na/Ca exchanger (NCX), sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA), plasma membrane Ca(2+)-ATPase (PMCA) and mitochondria to Ca(2+) clearance in somata of GCs. Somatic Ca(2+) clearance was increased by about 50% as GCs matured. NCX activity increased proportionally during ma...
Source: Cell Calcium - April 30, 2009 Category: Cytology Authors: Lee SH, Ho WK, Lee SH Tags: Cell Calcium Source Type: journals

Unique isoform-specific properties of calsequestrin in the heart and skeletal muscle.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Calcium signaling in myocytes is dependent on the cardiac ryanodine receptor (RyR2) calcium release channel and the calcium buffering protein in the sarcoplasmic reticulum, cardiac calsequestrin (CSQ2). The overall properties of CSQ2 and its regulation of RyR2 have not been explored in detail or directly compared with skeletal CSQ1 and its regulation of the skeletal RyR1, with physiological ionic strength and Ca(2+) concentrations. We find that there are major differences between the two isoforms under these physiological conditions. Ca(2+) binding to CSQ2 is 50% lower than to CSQ1. Only approximately 30% of CSQ2 is bo...
Source: Cell Calcium - April 30, 2009 Category: Cytology Authors: Wei L, Hanna AD, Beard NA, Dulhunty AF Tags: Cell Calcium Source Type: journals