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Tumor Necrosis Factor Induces Apoptosis in Hepatoma Cells by Increasing Ca2+Release from the Endoplasmic Reticulum and Suppressing Bcl-2 Expression

Byung-Chul Kim, Heung-Tae Kim, Mizuko Mamura, Indu S. Ambudkar, Kyeong-Sook Choi, Seong-Jin Kim
2002 Journal of Biological Chemistry  
Tumor necrosis factor (TNF) plays an import role in the control of apoptosis. The most well known apoptotic pathway regulated by TNF involves the TNFR1-associated death domain protein, Fas-associated death domain protein, and caspase-8. This study examines the mechanism of TNF-induced apoptosis in FaO rat hepatoma cells. TNF treatment significantly increased the percentage of apoptotic cells. TNF did not activate caspase-8 but activated caspase-3, -10, and -12. The effect of TNF on the
more » ... TNF on the expression of different members of the Bcl-2 family in these cells was studied. We observed no detectable changes in the steady-state levels of Bcl-X L , Bax, and Bid, although TNF suppresses Bcl-2 expression. Dantrolene suppressed the inhibitory effect of TNF on Bcl-2 expression. TNF induced release of Ca 2؉ from the endoplasmic reticulum (ER) that was blocked by dantrolene. Importantly, the expression of Bcl-2 blocked TNF-induced apoptosis and decreased TNF-induced Ca 2؉ release. These results suggest that TNF induces apoptosis by a mechanism that involves increasing Ca 2؉ release from the ER and suppression of Bcl-2 expression.
doi:10.1074/jbc.m203465200 pmid:12077131 fatcat:rd6dk3v5tfc2nhecnag5byd4vq