TY - JOUR
T1 - Decreased ER-associated degradation of α-TCR induced by Grp78 depletion with the SubAB cytotoxin
AU - Lass, Agnieszka
AU - Kujawa, Marek
AU - McConnell, Elizabeth
AU - Paton, Adrienne W.
AU - Paton, James C.
AU - Wójcik, Cezary
N1 - Funding Information:
We acknowledge Dr. George N. DeMartino (UT Southwestern, Dallas, TX) for the generous gift of rabbit antisera detecting the α7, Rpt2 and Rpt5 subunits of the 26S proteasome. This research was supported by internal start-up funds of IU School of Medicine-Evansville (C.W.), as well as by the Program Grant 284214 from the National Health and Medical Research Council of Australia and NIH grant 1R01AI068715-01 (A.W.P. and J.C.P.).
PY - 2008
Y1 - 2008
N2 - HeLa cells stably expressing the α chain of T-cell receptor (αTCR), a model substrate of ER-associated degradation (ERAD), were used to analyze the effects of BiP/Grp78 depletion by the SubAB cytotoxin. SubAB induced XBP1 splicing, followed by JNK phosphorylation, eIF2α phosphorylation, upregulation of ATF3/4 and partial ATF6 cleavage. Other markers of ER stress, including elements of ERAD pathway, as well as markers of cytoplasmic stress, were not induced. SubAB treatment decreased absolute levels of αTCR, which was caused by inhibition of protein synthesis. At the same time, the half-life of αTCR was extended almost fourfold from 70 min to 210 min, suggesting that BiP normally facilitates ERAD. Depletion of p97/VCP partially rescued SubAB-induced depletion of αTCR, confirming the role of VCP in ERAD of αTCR. It therefore appears that ERAD of αTCR is driven by at least two different ATP-ase systems located at two sides of the ER membrane, BiP located on the lumenal side, while p97/VCP on the cytoplasmic side. While SubAB altered cell morphology by inducing cytoplasm vacuolization and accumulation of lipid droplets, caspase activation was partial and subsided after prolonged incubation. Expression of CHOP/GADD153 occurred only after prolonged incubation and was not associated with apoptosis.
AB - HeLa cells stably expressing the α chain of T-cell receptor (αTCR), a model substrate of ER-associated degradation (ERAD), were used to analyze the effects of BiP/Grp78 depletion by the SubAB cytotoxin. SubAB induced XBP1 splicing, followed by JNK phosphorylation, eIF2α phosphorylation, upregulation of ATF3/4 and partial ATF6 cleavage. Other markers of ER stress, including elements of ERAD pathway, as well as markers of cytoplasmic stress, were not induced. SubAB treatment decreased absolute levels of αTCR, which was caused by inhibition of protein synthesis. At the same time, the half-life of αTCR was extended almost fourfold from 70 min to 210 min, suggesting that BiP normally facilitates ERAD. Depletion of p97/VCP partially rescued SubAB-induced depletion of αTCR, confirming the role of VCP in ERAD of αTCR. It therefore appears that ERAD of αTCR is driven by at least two different ATP-ase systems located at two sides of the ER membrane, BiP located on the lumenal side, while p97/VCP on the cytoplasmic side. While SubAB altered cell morphology by inducing cytoplasm vacuolization and accumulation of lipid droplets, caspase activation was partial and subsided after prolonged incubation. Expression of CHOP/GADD153 occurred only after prolonged incubation and was not associated with apoptosis.
KW - Cytotoxin
KW - ER-associated degradation (ERAD)
KW - Subtilase
KW - T-cell receptor (TCR)
KW - Unfolded protein response (UPR)
KW - endoplasmic reticulum (ER)
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U2 - 10.1016/j.biocel.2008.06.003
DO - 10.1016/j.biocel.2008.06.003
M3 - Article
C2 - 18611445
AN - SCOPUS:51249096553
VL - 40
SP - 2865
EP - 2879
JO - International Journal of Biochemistry
JF - International Journal of Biochemistry
SN - 1357-2725
IS - 12
ER -