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Intracellular ATP is required for actinomycin D-induced apoptotic cell death in HeLa cells
1Graduate Institute of Pharmacology, Yang Ming Medical College, Taiwan, Republic of China.
Abstract:
In the present report, we demonstrate that reduction of cellular ATP content with antimycin A blocks actinomycin D-induced apoptotic cell death in HeLa cells. Compared to cells (approximately 80%) treated with actinomycin D (1 microgram/ml; 48 h) alone in glucose-containing medium, a much smaller percentage of cells (approximately 20%) treated with actinomycin D in the presence of antimycin A in glucose-free medium shows morphological characteristic of apoptosis. ATP-depleted cells with or without actinomycin D treatment, on the other hand, die necrotically. In cells under actinomycin D short exposure treatment (1 microgram/ml; 1 h), apoptosis occurs when cellular ATP content is rapidly recovered after the removal of antimycin A and resupplementation of glucose-containing medium. In the incubation of isolated Triton-permeabilized cells with ATP ( > 0.5 mM), apoptotic nuclei become abundant 4 h after ATP treatment. These results implicate the requirement of ATP for the induction of apoptosis.
Insights
Cellular ATP depletion prevents actinomycin D-induced apoptosis in HeLa cells. Apoptosis requires ATP for induction, as demonstrated by its blockage when ATP levels are reduced, and its restoration upon ATP repletion.
Area of Science:
- Cell Biology
- Biochemistry
Background:
- Apoptosis, or programmed cell death, is a critical cellular process.
- The role of cellular energy status, specifically adenosine triphosphate (ATP) levels, in regulating apoptosis is not fully understood.
Purpose of the Study:
- To investigate the role of cellular ATP content in the induction of actinomycin D-induced apoptosis in HeLa cells.
Main Methods:
- HeLa cells were treated with actinomycin D and antimycin A (an ATP-depleting agent) in glucose-containing and glucose-free media.
- Morphological characteristics of apoptosis were assessed.
- Triton-permeabilized cells were incubated with varying concentrations of ATP.
Main Results:
- Reduction of cellular ATP content using antimycin A significantly blocked actinomycin D-induced apoptosis.
- ATP-depleted cells, with or without actinomycin D, underwent necrotic cell death.
- Apoptosis was induced when cellular ATP levels were restored after a short exposure to actinomycin D.
- Abundant apoptotic nuclei were observed in isolated permeabilized cells upon ATP repletion.
Conclusions:
- Cellular ATP is required for the induction of apoptosis.
- Energy depletion shifts the mode of cell death from apoptosis to necrosis.