Related Experiment Videos
Tributyltin-induced apoptosis requires glycolytic adenosine trisphosphate production
1Institute of Environmental Medicine, Division of Toxicology, Karolinska Institutet, Box 210, S-171 77 Stockholm, Sweden.
Abstract:
The toxicity of tributyltin chloride (TBT) involves Ca(2+) overload, cytoskeletal damage, and mitochondrial failure leading to cell death by apoptosis or necrosis. Here, we examined whether the intracellular ATP level modulates the mode of cell death after exposure to TBT. When Jurkat cells were energized by the mitochondrial substrate, pyruvate, low concentrations of TBT (1-2 microM) triggered an immediate depletion of intracellular ATP followed by necrotic death. When ATP levels were maintained by the addition of glucose, the mode of cell death was typically apoptotic. Glycolytic ATP production was required for apoptosis at two distinct steps. First, maintenance of adequate ATP levels accelerated the decrease of mitochondrial membrane potential, and the release of the intermembrane proteins adenylate kinase and cytochrome c from mitochondria. A possible role of the adenine nucleotide exchanger in this first ATP-dependent step is suggested by experiments performed with the specific inhibitor, bongkrekic acid. This substance delayed cytochrome c release in a manner similar to that caused by ATP depletion. Second, caspase activation following cytochrome c release was only observed in ATP-containing cells. Bcl-2 had only a minor effect on TBT-triggered caspase activation or cell death. We conclude that intracellular ATP concentrations control the mode of cell death in TBT-treated Jurkat cells at both the mitochondrial and caspase activation levels.
Insights
Intracellular ATP levels dictate cell death pathways in tributyltin chloride (TBT) exposed Jurkat cells. High ATP promotes apoptosis, while low ATP levels lead to necrosis, revealing TBT toxicity mechanisms.
Area of Science:
- Biochemistry
- Cell Biology
- Toxicology
Background:
- Tributyltin chloride (TBT) toxicity is linked to calcium overload, cytoskeletal damage, and mitochondrial dysfunction.
- Cell death can occur via apoptosis or necrosis, pathways influenced by cellular energy status.
Purpose of the Study:
- To investigate the role of intracellular adenosine triphosphate (ATP) levels in determining the mode of cell death induced by TBT exposure.
- To elucidate the specific mechanisms by which ATP influences TBT-induced cell death pathways.
Main Methods:
- Jurkat cells were treated with varying concentrations of TBT under different metabolic conditions (pyruvate vs. glucose).
- Intracellular ATP levels, mitochondrial membrane potential, and release of intermembrane proteins (adenylate kinase, cytochrome c) were measured.
- Caspase activation and the effect of Bcl-2 were assessed.
Main Results:
- Low TBT concentrations with pyruvate (low ATP) induced necrotic cell death.
- TBT exposure in the presence of glucose (maintained ATP) resulted in apoptotic cell death.
- Adequate ATP levels accelerated mitochondrial membrane potential decrease and cytochrome c release.
- Caspase activation was dependent on the presence of ATP following cytochrome c release.
Conclusions:
- Intracellular ATP concentration is a critical determinant of cell death mode (apoptosis vs. necrosis) in TBT-treated Jurkat cells.
- ATP influences TBT toxicity at both the mitochondrial release and caspase activation stages.
- The findings highlight the complex interplay between cellular energy metabolism and programmed cell death pathways.