Depletion of Endoplasmic Reticulum Calcium Stores Protects against Hypoxia- and Mitochondrial Inhibitor-Induced Cellular Injury and Death

1997 ◽  
Vol 240 (1) ◽  
pp. 57-60 ◽  
Author(s):  
Shayla L. Waters ◽  
Jeremy K. Wong ◽  
Rick G. Schnellmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Stores ◽  
Cellular Injury ◽  
Endoplasmic Reticulum Calcium ◽  
Mitochondrial Inhibitor

Heterologous expression of polycystin-1 inhibits endoplasmic reticulum calcium leak in stably transfected MDCK cells

2008 ◽  
Vol 294 (6) ◽  
pp. F1279-F1286 ◽  
Author(s):  
Kimberly H. Weber ◽  
Eun Kyung Lee ◽  
Uma Basavanna ◽  
Sabina Lindley ◽  
Roy C. Ziegelstein ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Release ◽  
Mdck Cells ◽  
Calcium Ionophore ◽  
Calcium Flux ◽  
Calcium Stores ◽  
Endoplasmic Reticulum Calcium ◽  
Calcium Indicator ◽  
Luminal Calcium ◽  
Er Membrane

We previously found that polycystin-1 accelerated the decay of ligand-activated cytoplasmic calcium transients through enhanced reuptake of calcium into the endoplasmic reticulum (ER; Hooper KM, Boletta A, Germino GG, Hu Q, Ziegelstein RC, Sutters M. Am J Physiol Renal Physiol 289: F521–F530, 2005). Calcium flux across the ER membrane is determined by the balance of active uptake and passive leak. In the present study, we show that polycystin-1 inhibited calcium leak across the ER membrane, an effect that would explain the capacity of this protein to accelerate clearance of calcium from the cytoplasm following a calcium release response. Calcium leak was detected by measurement of the accumulation of calcium in the cytoplasm following treatment with thapsigargin. Heterologous polycystin-1, stably expressed in Madin-Darby canine kidney cells, attenuated the thapsigargin-induced calcium peak with no effect on basal calcium stores, mitochondrial calcium uptake, or extrusion of calcium across the plasma membrane. The capacity of polycystin-1 to limit the rate of decay of ER luminal calcium following inhibition of the pump was shown indirectly using the calcium ionophore ionomycin, and directly by loading the ER with a low-affinity calcium indicator. We conclude that disruption of ER luminal calcium homeostasis may contribute to the cyst phenotype in autosomal dominant polycystic kidney disease.

Effect of a toxic glutamate challenge on the endoplasmic reticulum calcium stores in mammalian central neurones

1998 ◽  
Vol 5 ◽  
pp. 135
Author(s):  
V. Pinelis ◽  
D. Fajuk ◽  
L. Khaspekov ◽  
T. Storozhevykh ◽  
N. Vinskaya ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Stores ◽  
Endoplasmic Reticulum Calcium

Endoplasmic reticulum Ca2+-ATPase pump is up-regulated in calcium-transporting dental enamel cells: a non-housekeeping role for SERCA2b

2001 ◽  
Vol 358 (1) ◽  
pp. 217-224 ◽  
Author(s):  
Isobel K. FRANKLIN ◽  
Robert A. WINZ ◽  
Michael J. HUBBARD
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Transport ◽  
Dominant Role ◽  
Dental Enamel ◽  
Northern Analysis ◽  
Calcium Stores ◽  
Physiological Regulation ◽  
Calcium Dependent ◽  
Endoplasmic Reticulum Calcium ◽  
Quantitative Immunoblotting

Dental enamel-forming cells face a major challenge to avoid the cytotoxic effects of excess calcium. We have characterized sarcoplasmic/endoplasmic reticulum calcium-ATPase pumps (SERCA) in rat enamel cells to address the proposal that non-mitochondrial calcium stores play a dominant role in transcellular calcium transport. A single major isoform, SERCA2b, was detected during the protein-secretory and calcium-transport stages of enamel formation using reverse-transcriptase PCR, cDNA cloning, Northern analysis and immunoblotting. Most importantly, SERCA2b exhibited a specific 3-fold up-regulation to high expression levels during calcium transport, as determined by quantitative immunoblotting and ATPase assays. Sensitivity of the calcium-dependent ATPase to thapsigargin and three other SERCA inhibitors was characterized. These findings indicate that enamel cells are well-equipped to sequester calcium in endoplasmic reticulum stores and so protect against calcium toxicity, associate SERCA with transcellular calcium transport for the first time, and establish SERCA2b as a molecular and pharmacological target for future investigations of calcium transcytosis. The observed physiological regulation in enamel cells contradicts the widespread perception that SERCA2b is restricted to general housekeeping duties.

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.

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