scholarly journals Redox-assisted regulation of Ca2+ homeostasis in the endoplasmic reticulum by disulfide reductase ERdj5

2016 ◽  
Vol 113 (41) ◽  
pp. E6055-E6063 ◽  
Author(s):  
Ryo Ushioda ◽  
Akitoshi Miyamoto ◽  
Michio Inoue ◽  
Satoshi Watanabe ◽  
Masaki Okumura ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Disulfide Bond ◽  
Plasma Membranes ◽  
Dependent Manner ◽  
Cellular Functions ◽  
Endoplasmic Reticulum Calcium ◽  
Disulfide Reductase ◽  
Intracellular Ca ◽  
Activity Dependent ◽  
Er Calcium

Calcium ion (Ca2+) is an important second messenger that regulates numerous cellular functions. Intracellular Ca2+ concentration ([Ca2+]i) is strictly controlled by Ca2+ channels and pumps on the endoplasmic reticulum (ER) and plasma membranes. The ER calcium pump, sarco/endoplasmic reticulum calcium ATPase (SERCA), imports Ca2+ from the cytosol into the ER in an ATPase activity-dependent manner. The activity of SERCA2b, the ubiquitous isoform of SERCA, is negatively regulated by disulfide bond formation between two luminal cysteines. Here, we show that ERdj5, a mammalian ER disulfide reductase, which we reported to be involved in the ER-associated degradation of misfolded proteins, activates the pump function of SERCA2b by reducing its luminal disulfide bond. Notably, ERdj5 activated SERCA2b at a lower ER luminal [Ca2+] ([Ca2+]ER), whereas a higher [Ca2+]ER induced ERdj5 to form oligomers that were no longer able to interact with the pump, suggesting [Ca2+]ER-dependent regulation. Binding Ig protein, an ER-resident molecular chaperone, exerted a regulatory role in the oligomerization by binding to the J domain of ERdj5. These results identify ERdj5 as one of the master regulators of ER calcium homeostasis and thus shed light on the importance of cross talk among redox, Ca2+, and protein homeostasis in the ER.

Mitochondrial Ca2+ Activates a Cation Current in Aplysia Bag Cell Neurons

2010 ◽  
Vol 103 (3) ◽  
pp. 1543-1556 ◽  
Author(s):  
Charlene M. Hickey ◽  
Julia E. Geiger ◽  
Chris J. Groten ◽  
Neil S. Magoski
Keyword(s):  
Endoplasmic Reticulum ◽  
Ion Channels ◽  
Time Course ◽  
Reversal Potential ◽  
Neuroendocrine Cells ◽  
Dependent Manner ◽  
Inward Current ◽  
Cation Current ◽  
Intracellular Ca ◽  
Bag Cell Neurons

Ion channels may be gated by Ca2+ entering from the extracellular space or released from intracellular stores—typically the endoplasmic reticulum. The present study examines how Ca2+ impacts ion channels in the bag cell neurons of Aplysia californica. These neuroendocrine cells trigger ovulation through an afterdischarge involving Ca2+ influx from Ca2+ channels and Ca2+ release from both the mitochondria and endoplasmic reticulum. Liberating mitochondrial Ca2+ with the protonophore, carbonyl cyanide-4-trifluoromethoxyphenyl-hydrazone (FCCP), depolarized bag cell neurons, whereas depleting endoplasmic reticulum Ca2+ with the Ca2+-ATPase inhibitor, cyclopiazonic acid, did not. In a concentration-dependent manner, FCCP elicited an inward current associated with an increase in conductance and a linear current/voltage relationship that reversed near −40 mV. The reversal potential was unaffected by changing intracellular Cl−, but left-shifted when extracellular Ca2+ was removed and right-shifted when intracellular K+ was decreased. Strong buffering of intracellular Ca2+ decreased the current, although the response was not altered by blocking Ca2+-dependent proteases. Furthermore, fura imaging demonstrated that FCCP elevated intracellular Ca2+ with a time course similar to the current itself. Inhibiting either the V-type H+-ATPase or the ATP synthetase failed to produce a current, ruling out acidic Ca2+ stores or disruption of ATP production as mechanisms for the FCCP response. Similarly, any involvement of reactive oxygen species potentially produced by mitochondrial depolarization was mitigated by the fact that dialysis with xanthine/xanthine oxidase did not evoke an inward current. However, both the FCCP-induced current and Ca2+ elevation were diminished by disabling the mitochondrial permeability transition pore with the alkylating agent, N-ethylmaleimide. The data suggest that mitochondrial Ca2+ gates a voltage-independent, nonselective cation current with the potential to drive the afterdischarge and contribute to reproduction. Employing Ca2+ from mitochondria, rather than the more common endoplasmic reticulum, represents a diversification of the mechanisms that influence neuronal activity.

scholarly journals p.E152K-STIM1 mutation deregulates Ca2+ signaling contributing to chronic pancreatitis

2020 ◽  
Author(s):  
Miguel Burgos ◽  
Reginald Philippe ◽  
Fabrice Antigny ◽  
Paul Buscaglia ◽  
Emmanuelle Masson ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Chronic Pancreatitis ◽  
Acinar Cells ◽  
Pancreatic Acinar Cell ◽  
Pancreatic Acinar Cells ◽  
Endoplasmic Reticulum Calcium ◽  
Store Operated Calcium Entry ◽  
Intracellular Ca ◽  
Intracellular Changes ◽  
Main Regulator

ABSTRACTSince deregulation of intracellular Ca2+ can lead to intracellular trypsin activation and STIM1 (stromal interaction molecule-1) protein is the main regulator of Ca2+ homeostasis in pancreatic acinar cells, we explored the Ca2+ signaling in 37 STIM1 variants found in three pancreatitis patient cohorts. Extensive functional analysis of one particular variant, p.E152K, identified in three patients, provided a plausible link between dysregulated Ca2+ signaling within pancreatic acinar cells and chronic pancreatitis susceptibility. Specifically, p.E152K, located within the STIM1 EF-hand and sterile α-motif domain, increased the release of Ca2+ from the endoplasmic reticulum in patient-derived fibroblasts and transfected HEK293T cells. This event was mediated by altered STIM1-sarco/endoplasmic reticulum calcium transport ATPase (SERCA) interactions and enhanced SERCA pump activity leading to increased Store Operated Calcium Entry (SOCE). In the pancreatic AR42J cells expressing the p.E152K variant, Ca2+-signaling perturbations correlated with defects in trypsin activation and secretion, and increased cytotoxicity after cholecystokinin stimulation.Summary statementp.E152K-STIM1 variant found in pancreatitis patients leads to intracellular changes in calcium homeostasis through SERCA interaction, enabling intracellular trypsin activation and pancreatic acinar cell death.

Effect of digitonin on rat myometrium subcellular membrane fractions

1981 ◽  
Vol 59 (11) ◽  
pp. 1128-1133 ◽  
Author(s):  
A. K. Grover ◽  
C. Y. Kwan ◽  
J. Crankshaw ◽  
E. E. Daniel
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Cytochrome C ◽  
Plasma Membranes ◽  
Dependent Manner ◽  
Mitochondrial Marker ◽  
Concentration Dependent Manner ◽  
Subcellular Membrane ◽  
Ca Uptake ◽  
Isopycnic Centrifugation

Isopycnic centrifugation experiments using sucrose density gradients showed that in digitonin-treated microsomes the distribution of the plasma membrane (PM) marker 5′-nucleotidase was shifted to higher densities. The treatment also caused similar but less pronounced changes in the distribution of protein, the putative endoplasmic reticulum (ER) marker NADPH-dependent cytochrome c reductase, and the inner mitochondrial marker cytochrome c oxidase. Similar experiments using more purified membrane fractions showed that the digitonin treatment led to a comparable increase in the densities of the fractions N1 and N2 previously described as subfractions of plasma membrane and to considerably less increase in the density of the fraction N3B which is enriched in the endoplasmic reticulum and the inner mitochondrial markers. Digitonin inhibited the ATP-dependent Ca uptake by the N1 fraction in a concentration-dependent manner (I50 = 0.3 mg/mL). Digitonin (0.5 mg/mL) inhibited the ATP-dependent azide-insensitive Ca uptake by all the fractions. The results support the hypothesis that (a) N1 and N2 are subfractions of plasma membrane, and (b) ATP-dependent azide-insensitive Ca uptake in rat myometrium is a property of plasma membranes.

Econazole induces increases in free intracellular Ca2+ concentrations in human osteosarcoma cells

2005 ◽  
Vol 24 (9) ◽  
pp. 453-458 ◽  
Author(s):  
H-T Chang ◽  
C-S Liu ◽  
C-T Chou ◽  
C-H Hsieh ◽  
C-H Chang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Phospholipase C ◽  
Dependent Manner ◽  
Osteosarcoma Cells ◽  
Independent Manner ◽  
Concentration Dependent Manner ◽  
Human Osteosarcoma Cells ◽  
Intracellular Ca ◽  
In Vitro Effects

Econazole is an antifungal drug with different in vitro effects. However, econazole's effect on osteoblast like cells is unknown. In human MG63 osteosarcoma cells, the effect of econazole on intracellular Ca2+ concentrations ([Ca2+]i) was explored by using fura-2. At a concentration of 0.1 μM, econazole started to cause a rise in [Ca2+]i in a concentration-dependent manner. Econazole-induced [Ca2+]i rise was reduced by 74% by removal of extracellular Ca2+. The econazole-induced Ca2+ influx was mediated via a nimodipine-sensitive pathway. In Ca2+ free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ ATPase, caused a [Ca2+]i rise, after which the increasing effect of econazole on [Ca2+]i was abolished. Pretreatment of cells with econazole to deplete Ca2+ stores totally prevented thapsigargin from releasing Ca2+. U73122, an inhibitor of phospholipase C, abolished histamine (an inositol 1,4,5-trisphosphate dependent Ca2+ mobilizer)-induced, but not econazoleinduced, [Ca2+]i rise. Econazole inhibited 76% of thapsigargin-induced store-operated Ca2+ entry. These findings suggest that in MG63 osteosarcoma cells, econazole increases [Ca2+]i by stimulating Ca2+ influx and Ca2+ release from the endoplasmic reticulum via a phospholipase C-independent manner. In contrast, econazole acts as a potent blocker of store-operated Ca2+ entry.

scholarly journals Selenoprotein N is an endoplasmic reticulum calcium sensor that links luminal calcium levels to a redox activity

2020 ◽  
Vol 117 (35) ◽  
pp. 21288-21298 ◽  
Author(s):  
Alexander Chernorudskiy ◽  
Ersilia Varone ◽  
Sara Francesca Colombo ◽  
Stefano Fumagalli ◽  
Alfredo Cagnotto ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Single Amino Acid ◽  
Redox Activity ◽  
Calcium Stores ◽  
Calcium Sensor ◽  
Oligomeric State ◽  
Endoplasmic Reticulum Calcium ◽  
Ef Hand ◽  
Luminal Calcium ◽  
Er Calcium

The endoplasmic reticulum (ER) is the reservoir for calcium in cells. Luminal calcium levels are determined by calcium-sensing proteins that trigger calcium dynamics in response to calcium fluctuations. Here we report that Selenoprotein N (SEPN1) is a type II transmembrane protein that senses ER calcium fluctuations by binding this ion through a luminal EF-hand domain. In vitro and in vivo experiments show that via this domain, SEPN1 responds to diminished luminal calcium levels, dynamically changing its oligomeric state and enhancing its redox-dependent interaction with cellular partners, including the ER calcium pump sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA). Importantly, single amino acid substitutions in the EF-hand domain of SEPN1 identified as clinical variations are shown to impair its calcium-binding and calcium-dependent structural changes, suggesting a key role of the EF-hand domain in SEPN1 function. In conclusion, SEPN1 is a ER calcium sensor that responds to luminal calcium depletion, changing its oligomeric state and acting as a reductase to refill ER calcium stores.

scholarly journals Calcium dynamics and homeostasis in a mathematical model of the principal cell of the cortical collecting tubule.

1996 ◽  
Vol 107 (2) ◽  
pp. 207-230 ◽  
Author(s):  
Y Tang ◽  
J L Stephenson
Keyword(s):  
Mathematical Model ◽  
Endoplasmic Reticulum ◽  
Basolateral Membrane ◽  
Homogeneous Medium ◽  
Principal Cell ◽  
Endoplasmic Reticulum Calcium ◽  
Na Permeability ◽  
Collecting Tubule ◽  
Intracellular Ca ◽  
Cortical Collecting Tubule

Calcium (Ca) dynamics are incorporated into a mathematical model of the principal cell in the cortical collecting tubule developed earlier in Strieter et al. (1992a. Am. J Physiol. 263:F1063-1075). The Ca components are modeled after the Othmer-Tang model for IP(3)-sensitive calcium channels (1993, in Experimental and Theoretical Advances in Biological Pattern Formation, 295-319). There are IP(3)-sensitive Ca channels and ATP-driven pumps on the membrane of the endoplasmic reticulum. Calcium enters the cell passively down its electrochemical gradient. A Ca pump and Na/Ca exchange in the basolateral membrane are responsible for the extrusion of cytoplasmic calcium. Na/Ca exchange can also operate in reverse mode to transport Ca into the cell. Regulatory effects of cytoplasmic Ca on the apical Na channels are modeled after experimental data that indicate apical Na permeability varies inversely with cytoplasmic Ca concentration. Numerical results on changes in intracellular Ca caused by decreasing NaCl in the bath and the lumen are similar to those from experiments in Bourdeau and Lau (1990. Am. J Physiol. 258:F1497-1503). This match of simulation and experiment requires the synergistic action of the Na/Ca exchanger and the Ca regulated apical Na permeability. In a homogeneous medium, cytoplasmic Ca becomes oscillatory when extracellular Na is severely decreased, as observed in experiments of cultured principal cells (Koster, H., C. van Os and R. Bindels. 1993. Kidney Int.43:828-836). This essentially pathological situation arises because the hyperpolarization of membrane potential caused by Na-free medium increases Ca influx into the cell, while the Na/Ca exchanger is inactivated by the low extracellular Na and can no longer move Ca out of the cell effectively. The raising of the total amount of intracellular Ca induces oscillatory Ca movement between the cytoplasm and the endoplasmic reticulum. Ca homeostasis is investigated under the condition of severe extracellular Ca variations. As extracellular Ca is decreased, Ca regulation is greatly impaired if Ca does not regulate apical ionic transport. The simulations indicate that the Na/Ca exchanger alone has only limited regulatory capacity. The Ca regulated apical sodium or potassium permeability are essential for regulation of cytoplasmic Ca in the principal cell of the cortical collecting tubule.

Expression of polycystin-1 enhances endoplasmic reticulum calcium uptake and decreases capacitative calcium entry in ATP-stimulated MDCK cells

2005 ◽  
Vol 289 (3) ◽  
pp. F521-F530 ◽  
Author(s):  
K. M. Hooper ◽  
A. Boletta ◽  
G. G. Germino ◽  
Q. Hu ◽  
R. C. Ziegelstein ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Homeostasis ◽  
Mdck Cells ◽  
Fluid Secretion ◽  
Calcium Entry ◽  
Loss Of Function ◽  
Capacitative Calcium Entry ◽  
Endoplasmic Reticulum Calcium ◽  
Cell Calcium ◽  
Er Calcium

Autosomal dominant polycystic kidney disease (ADPKD) types 1 and 2 arise as a consequence of mutations in the PKD1 or PKD2 genes, encoding polycystins-1 and -2. Because loss of function of either of the polycystins leads to a very similar phenotype and the two proteins are known to interact, polycystins-1 and -2 are probably active in the same pathway. The way in which loss of either polycystin leads to the development of ADPKD remains to be established, but disturbances of cell calcium regulation are likely to play an important role. Here, we demonstrate that polycystin-1, heterologously expressed in Madin-Darby canine kidney cells, had a pronounced effect on intracellular calcium homeostasis. ATP-induced calcium responses in transfection control cells exhibited a double peak and relatively gradual return to baseline. By contrast, cells expressing heterologous polycystin-1 showed a brief, uniphasic peak and an accelerated rate of decay. Heterologously expressed polycystin-1 accelerated endoplasmic reticulum (ER) calcium reuptake and inhibited capacitative calcium entry; we found no effect of the protein on mitochondrial calcium buffering or plasma membrane calcium extrusion. We therefore propose that polycystin-1 accelerated the decay of the cell calcium response to ATP by upregulation of ER calcium reuptake and consequent minimization of the stimulus for capacitative calcium entry. It is possible that cellular dedifferentiation, fluid secretion, and proliferation might therefore arise in ADPKD as a consequence of disturbances in cytoplasmic and ER calcium homeostasis and aberrant capacitative calcium entry.

scholarly journals Trace levels of peptidoglycan in serum underlie the NOD-dependent cytokine response to endoplasmic reticulum stress

2019 ◽  
Author(s):  
Raphael Molinaro ◽  
Robert Flick ◽  
Dana J. Philpott ◽  
Stephen E. Girardin
Keyword(s):  
Cell Culture ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Calf Serum ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Dependent Manner ◽  
Intracellular Ca ◽  
Inflammatory Signalling

AbstractNOD1 and NOD2 are intracellular sensors of bacterial peptidoglycan that belong to the Nod-like receptor (NLR) family of innate immune proteins. In addition to their role as direct bacterial sensors, it was recently proposed that NOD proteins could detect endoplasmic reticulum (ER) stress induced by thapsigargin, an inhibitor of the sarcoplasmic or endoplasmic reticulum calcium ATPase family (SERCA) that pumps Ca2+into the ER, resulting in pro-inflammatory signalling. Here, we confirm that thapsigargin induces pro-inflammatory signalling in epithelial cells in a NOD-dependent manner. However, the effect was specific to thapsigargin, as tunicamycin and the subtilase cytotoxin SubAB from Shiga toxigenicEscherichia coli,which induce ER stress by other mechanisms, did not induce cytokine expression. The calcium ionophore A23187 also induced NOD-dependent signalling, and the calcium chelator BAPTA-AM blunted thapsigargin-dependent pro-inflammatory signalling, showing NOD proteins responded to a rise in intracellular Ca2+. Since intracellular Ca2+directly affects vesicular trafficking, we tested if thapsigargin-induced NOD activation required endocytosis. Our results demonstrate that both endocytosis and the addition of serum to the cell culture medium were required for thapsigargin-mediated NOD activation. Finally, we analyzed cell culture grade fetal calf serum as well as serum from laboratory mice by high-pressure liquid chromatography and mass spectrometry, and identified the presence of various peptidoglycan fragments. We propose that cellular perturbations that affect intracellular Ca2+can trigger internalization of peptidoglycan trace contaminants found in culture serum, thereby stimulating pro-inflammatory signalling. The presence of peptidoglycan in animal serum suggests that a homeostatic function of NOD signalling may have been previously overlooked.

scholarly journals The p.E152K-STIM1 mutation deregulates Ca2+ signaling contributing to chronic pancreatitis

2021 ◽  
Vol 134 (3) ◽  
pp. jcs244012 ◽  
Author(s):  
Miguel Burgos ◽  
Reginald Philippe ◽  
Fabrice Antigny ◽  
Paul Buscaglia ◽  
Emmanuelle Masson ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Chronic Pancreatitis ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Endoplasmic Reticulum Calcium ◽  
Ef Hand ◽  
Pump Activity ◽  
Intracellular Ca ◽  
Serca Pump ◽  
Main Regulator

ABSTRACTSince deregulation of intracellular Ca2+ can lead to intracellular trypsin activation, and stromal interaction molecule-1 (STIM1) protein is the main regulator of Ca2+ homeostasis in pancreatic acinar cells, we explored the Ca2+ signaling in 37 STIM1 variants found in three pancreatitis patient cohorts. Extensive functional analysis of one particular variant, p.E152K, identified in three patients, provided a plausible link between dysregulated Ca2+ signaling within pancreatic acinar cells and chronic pancreatitis susceptibility. Specifically, p.E152K, located within the STIM1 EF-hand and sterile α-motif domain, increased the release of Ca2+ from the endoplasmic reticulum in patient-derived fibroblasts and transfected HEK293T cells. This event was mediated by altered STIM1–sarco/endoplasmic reticulum calcium transport ATPase (SERCA) conformational change and enhanced SERCA pump activity leading to increased store-operated Ca2+ entry (SOCE). In pancreatic AR42J cells expressing the p.E152K variant, Ca2+ signaling perturbations correlated with defects in trypsin activation and secretion, and increased cytotoxicity after cholecystokinin stimulation.This article has an associated First Person interview with the first author of the paper.

scholarly journals Endoplasmic Reticulum Calcium Pumps and Tumor Cell Differentiation

2020 ◽  
Vol 21 (9) ◽  
pp. 3351
Author(s):  
Bela Papp ◽  
Sophie Launay ◽  
Pascal Gélébart ◽  
Atousa Arbabian ◽  
Agnes Enyedi ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Differentiation ◽  
Calcium Homeostasis ◽  
Leukemia Cell ◽  
Cell Types ◽  
Ion Concentration ◽  
Endoplasmic Reticulum Calcium ◽  
Calcium Pumps ◽  
Dependent Transport ◽  
Er Calcium

Endoplasmic reticulum (ER) calcium homeostasis plays an essential role in cellular calcium signaling, intra-ER protein chaperoning and maturation, as well as in the interaction of the ER with other organelles. Calcium is accumulated in the ER by sarco/endoplasmic reticulum calcium ATPases (SERCA enzymes) that generate by active, ATP-dependent transport, a several thousand-fold calcium ion concentration gradient between the cytosol (low nanomolar) and the ER lumen (high micromolar). SERCA enzymes are coded by three genes that by alternative splicing give rise to several isoforms, which can display isoform-specific calcium transport characteristics. SERCA expression levels and isoenzyme composition vary according to cell type, and this constitutes a mechanism whereby ER calcium homeostasis is adapted to the signaling and metabolic needs of the cell, depending on its phenotype, its state of activation and differentiation. As reviewed here, in several normal epithelial cell types including bronchial, mammary, gastric, colonic and choroid plexus epithelium, as well as in mature cells of hematopoietic origin such as pumps are simultaneously expressed, whereas in corresponding tumors and leukemias SERCA3 expression is selectively down-regulated. SERCA3 expression is restored during the pharmacologically induced differentiation of various cancer and leukemia cell types. SERCA3 is a useful marker for the study of cell differentiation, and the loss of SERCA3 expression constitutes a previously unrecognized example of the remodeling of calcium homeostasis in tumors.

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