The role of endoplasmic reticular Ca2+ stores in cell viability and tumor necrosis factor-alpha production of the murine macrophage RAW 264.7 cell line
Yj. Chen et Sy. Lin-shiau, The role of endoplasmic reticular Ca2+ stores in cell viability and tumor necrosis factor-alpha production of the murine macrophage RAW 264.7 cell line, J BIOMED SC, 7(2), 2000, pp. 122-127
Thapsigargin (TG), an endoplasmic reticular (ER) Ca2+-ATPase inhibitor, can
increase the intracellular calcium concentration and then deplete the TG-s
ensitive intracellular Ca2+ pool. In this study, we investigated the effect
s of TG on cell viability and tumor necrosis factor-alpha (TNF-alpha) produ
ction in the murine macrophage RAW 264.7 cell tine. We found that treatment
with TG (10-800 nM) induced apoptosis in RAW 264.7 cells in a dose-depende
nt manner (IC50, 200 nM). Lipopolysaccharide (LPS, 1 mu g/ml) markedly pote
ntiated low concentrations of TG (10-75 nM) in inducing apoptosis (IC50, 20
nM) as revealed by the DNA ladder. Polymycin B (an LPS receptor antagonist
) inhibited the cytotoxic effect induced by LPS plus TG. Although TG, A2318
7 and ionomycin all definitely increased intracellular Ca2+ concentrations,
neither A23187 nor ionomycin mimicked TG in inducing apoptotic events in L
PS-activated RAW 264.7 cells. Moreover, the production of TNF-alpha induced
by LPS was profoundly potentiated by TG but not by A23187 or by ionomycin.
We conclude from these combined results that TG-sensitive ER Ca2+ stores p
lay a pivotal role in modulating cell viability and TNF-alpha production. T
he mutual potentiation between the LPS receptor signaling pathway and the d
epletion of ER Ca2+ stores implies the existence of cross-talk between thes
e multiregulatory mechanisms in this murine macrophage RAW 264.7 cell line.
Copyright (C) 2000 National Science council, ROC and S. Karger AG, Basel.