Elevated ceramide is downstream of altered calcium homeostasis in low serum-induced apoptosis

2000 ◽  
Vol 279 (5) ◽  
pp. C1640-C1647 ◽  
Author(s):  
Supriya Jayadev ◽  
J. Carl Barrett ◽  
Elizabeth Murphy
Keyword(s):  
Calcium Release ◽  
Calcium Depletion ◽  
Hamster Embryo Cells ◽  
Embryo Cells ◽  
Immortalized Cell ◽  
Induced Apoptosis ◽  
Ceramide Generation ◽  
The Relationship ◽  
Er Calcium ◽  
Low Serum

Two immortalized cell lines, sup (+) and sup (−), derived from mutagenized Syrian hamster embryo cells, were used to study the relationship and temporal order between calcium and ceramide signals during apoptosis. The early preneoplastic cells, termed sup (+), suppress tumorigenicity when hybridized with tumor cells, whereas later-stage sup (−) cells do not. In reduced serum conditions, sup (+) cells cease proliferating and undergo apoptosis; in contrast, sup (−) cells continue slow growth and undergo necrosis. In sup (+) cells, decreased endoplasmic reticulum (ER) calcium occurs 4 h after low serum treatment and precedes apoptosis. Significant elevations in ceramide are observed 16 h after reduced serum treatment of sup (+) cells but are not found in sup (−) cells. Inhibiting ER calcium depletion in low serum-treated sup (+) cells by treating with high levels of calcium prevents both ceramide generation and apoptosis. Conversely, inducing ER calcium depletion in sup (−) cells by treating with low serum plus thapsigargin results in elevated ceramide levels and apoptosis. Furthermore, C6-ceramide treatment induced apoptosis of sup (−) cells in low serum, a condition that does not normally cause apoptosis. C6-ceramide treatment did not induce apoptosis in either sup (+) or sup (−) cells in 10% serum but did cause G2/M arrest. These studies show that ceramide production is downstream of ER calcium release.

scholarly journals Calcium depletion challenges endoplasmic reticulum proteostasis by destabilising BiP-substrate complexes

2020 ◽  
Author(s):  
Steffen Preissler ◽  
Claudia Rato ◽  
Yahui Yan ◽  
Luke A. Perera ◽  
Aron Czako ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Release ◽  
Atp Hydrolysis ◽  
Secretory Cells ◽  
Nucleotide Exchange ◽  
Calcium Depletion ◽  
Er Quality Control ◽  
Cellular Processes ◽  
The Unfolded Protein Response ◽  
Er Calcium

AbstractThe metazoan endoplasmic reticulum (ER) serves both as a hub for maturation of secreted proteins and as an intracellular calcium storage compartment, facilitating calcium release-dependent cellular processes. ER calcium depletion robustly activates the unfolded protein response (UPR). However, it is unclear how fluctuations in ER calcium impact organellar proteostasis. Here we report that calcium selectively affects the dynamics of the abundant metazoan ER Hsp70 chaperone BiP, by enhancing its affinity for ADP. In the calcium replete ER, ADP rebinding to post-ATP hydrolysis BiP-substrate complexes competes with ATP binding during both spontaneous and co-chaperone-assisted nucleotide exchange, favouring substrate retention. Conversely, in the calcium depleted ER, relative acceleration of ADP-to-ATP exchange favours substrate release. These findings explain the rapid dissociation of certain substrates from BiP observed in the calcium-depleted ER and suggest a mechanism for tuning ER quality control and coupling UPR activity to signals that mobilise ER calcium in secretory cells.

scholarly journals Calcium depletion challenges endoplasmic reticulum proteostasis by destabilising BiP-substrate complexes

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Steffen Preissler ◽  
Claudia Rato ◽  
Yahui Yan ◽  
Luke A Perera ◽  
Aron Czako ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Release ◽  
Atp Hydrolysis ◽  
Secretory Cells ◽  
Nucleotide Exchange ◽  
Calcium Depletion ◽  
Er Quality Control ◽  
Cellular Processes ◽  
The Unfolded Protein Response ◽  
Er Calcium

The metazoan endoplasmic reticulum (ER) serves both as a hub for maturation of secreted proteins and as an intracellular calcium storage compartment, facilitating calcium-release-dependent cellular processes. ER calcium depletion robustly activates the unfolded protein response (UPR). However, it is unclear how fluctuations in ER calcium impact organellar proteostasis. Here, we report that calcium selectively affects the dynamics of the abundant metazoan ER Hsp70 chaperone BiP, by enhancing its affinity for ADP. In the calcium-replete ER, ADP rebinding to post-ATP hydrolysis BiP-substrate complexes competes with ATP binding during both spontaneous and co-chaperone-assisted nucleotide exchange, favouring substrate retention. Conversely, in the calcium-depleted ER, relative acceleration of ADP-to-ATP exchange favours substrate release. These findings explain the rapid dissociation of certain substrates from BiP observed in the calcium-depleted ER and suggest a mechanism for tuning ER quality control and coupling UPR activity to signals that mobilise ER calcium in secretory cells.

Transformation of hamster embryo cells by chymotrypsin-treated and untreated polyoma virus: characterization of transformants

1985 ◽  
Vol 31 (4) ◽  
pp. 356-360
Author(s):  
Vera Chlumecky ◽  
Donald C. Stranks ◽  
John S. Colter
Keyword(s):  
Common Species ◽  
Soft Agar ◽  
T Antigen ◽  
Polyoma Virus ◽  
Large T Antigen ◽  
T Antigens ◽  
Hamster Embryo Cells ◽  
Embryo Cells

The ability of chymotrypsin-treated (chymo+) and untreated (chymo−) polyoma virus to transform cultured hamster embryo fibroblasts was examined. The data show that exposure to this protease reduces the ability of the virus to transform non-permissive cells to essentially the same extent as it reduces its ability to replicate in permissive cells. Twenty-five lines of transformed cells were established from colonies growing in soft agar, and after 20 in vitro passages, cells of all lines were characterized with respect to their ability to form colonies in soft agar and their tumorigenicity in hamsters. While the studies showed that there are striking differences among the lines with respect to colony-forming ability, and real, though less striking differences in tumorigenicity, they failed to reveal any obvious differences between the groups of cell lines transformed by chymo− and chymo+ polyoma virus. Of 13 lines examined, all were found to express both middle and small polyoma T antigens, none express significant levels of large T antigen, and 11 express some form of what is probably a truncated large T antigen, the most common species having a molecular weight of 67 000.

scholarly journals In vitro Transformation of Hamster Embryo Cells with Tryptophan Pyrolysis Products

1977 ◽  
Vol 53 (3) ◽  
pp. 126-129 ◽  
Author(s):  
Shozo TAKAYAMA ◽  
Yoichi KATOH ◽  
Machiko TANAKA ◽  
Minako NAGAO ◽  
Keiji WAKABAYASHI ◽  
...  
Keyword(s):  
Pyrolysis Products ◽  
In Vitro Transformation ◽  
Hamster Embryo Cells ◽  
Embryo Cells
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