Related Experiment Videos
"Wages of fear": transient threefold decrease in intracellular ATP level imposes apoptosis.
Denis S Izyumov1, Armine V Avetisyan, Olga Yu Pletjushkina
1Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Moscow State University, Khokhlova Street 4, Moscow 119992, Russian Federation.
Biochimica Et Biophysica Acta
|July 30, 2004
Summary
A temporary drop in cellular ATP levels, caused by inhibiting energy production pathways, triggers apoptosis, or programmed cell death, in HeLa cells. This cell suicide mechanism is distinct from other known apoptosis pathways.
Area of Science:
- Cellular Biology
- Biochemistry
- Apoptosis Research
Background:
- Cellular energy homeostasis is crucial for survival.
- The role of intracellular ATP levels in regulating cell fate, particularly programmed cell death, remains incompletely understood.
Purpose of the Study:
- To investigate the consequences of transiently lowering intracellular ATP levels on HeLa cell viability.
- To elucidate the specific mechanisms and signaling pathways involved in ATP depletion-induced cell death.
Main Methods:
- HeLa cells were treated with inhibitors of oxidative phosphorylation (oligomycin, myxothiazol, FCCP) and glycolysis (DOG) to induce ATP depletion.
- ATP levels were measured, and cell death was assessed via apoptosis markers (Bax translocation, cytochrome c release, caspase activation, ROS generation, chromatin changes).
- The sensitivity of this apoptosis to various inhibitors (Bcl-2, zVADfmk, cyclosporine A, etc.) and other apoptosis inducers (TNF, H2O2) was evaluated.
Main Results:
- Combined inhibition of oxidative phosphorylation and partial glycolysis inhibition caused a threefold decrease in intracellular ATP, leading to apoptosis upon recovery.
- Separate inhibition of either pathway (10-35% ATP reduction) did not induce cell death.
- Apoptosis involved mitochondrial pathway activation and was sensitive to Bcl-2 and zVADfmk (which induced necrosis instead), but resistant to other inhibitors, distinguishing it from TNF- or H2O2-induced apoptosis.
Conclusions:
- Transient, significant depletion of intracellular ATP below a critical level (approx. 1 mM) can trigger a specific apoptotic cell death pathway in HeLa cells.
- This ATP-depletion-induced apoptosis is mediated by mitochondrial signaling and caspase activation but differs from other known apoptotic stimuli.
- The existence of intracellular 'ATP-meters' is proposed, which signal for cell suicide when ATP levels fall below a threshold.