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Modulation of passive permeability by external ATP and cytoskeleton-attacking agents in cultured mammalian cells
Abstract:
External ATP causes a passive permeability change in several transformed cells, but not in untransformed cells. We previously demonstrated that in CHO-K1 cells, a transformed clone of Chinese hamster ovary cells, the external ATP-dependent permeability change was induced when the intracellular ATP concentration was reduced by a mitochondrial inhibitor (Kitagawa, T. and Akamatsu, Y. (1981) Biochim. Biophys. Acta 649, 76-82). A permeability change with similar characteristics was also observed when the CHO cells were treated with external ATP and a cytoskeleton-attacking agent such as vinblastine or cytochalasin B. Just like mitochondrial inhibitors, vinblastine could increase the sensitivity of transformed 3T3 cells to external ATP but showed no effect on passive permeability of normal 3T3 cells. However, in contrast with the effect of the mitochondrial inhibitors, the cytoskeleton drugs caused the permeability change with little reduction of intracellular ATP concentration, suggesting different actions of these two kinds of drug on the permeability change. The present results suggest an important role of cytoskeletal structures in controlling the external ATP-dependent permeability change in transformed cells. Possible effects of intracellular ATP on cytoskeletal structures are also discussed.
Insights
External ATP alters cell permeability in transformed cells, not normal ones. Cytoskeleton drugs, unlike mitochondrial inhibitors, induce this change by affecting cell structures, not intracellular ATP levels.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- External ATP induces passive permeability changes in transformed cells, but not untransformed cells.
- Previous work showed mitochondrial inhibitors reduce intracellular ATP, enabling external ATP-induced permeability changes in CHO-K1 cells.
Purpose of the Study:
- To investigate the role of cytoskeletal structures in the external ATP-dependent permeability change in transformed cells.
- To differentiate the mechanisms of action between mitochondrial inhibitors and cytoskeleton-attacking agents on cell permeability.
Main Methods:
- Treatment of Chinese hamster ovary (CHO) cells and transformed 3T3 cells with external ATP.
- Application of mitochondrial inhibitors (e.g., to reduce intracellular ATP) and cytoskeleton-attacking agents (e.g., vinblastine, cytochalasin B).
- Monitoring of passive cell permeability and intracellular ATP concentration.
Main Results:
- Cytoskeleton drugs (vinblastine, cytochalasin B) induced permeability changes in CHO cells with external ATP, similar to mitochondrial inhibitors.
- Vinblastine increased transformed 3T3 cell sensitivity to external ATP without affecting normal 3T3 cells.
- Unlike mitochondrial inhibitors, cytoskeleton drugs caused permeability changes with minimal reduction in intracellular ATP.
Conclusions:
- Cytoskeletal structures play a crucial role in controlling external ATP-dependent permeability changes in transformed cells.
- The mechanisms by which mitochondrial inhibitors and cytoskeleton drugs affect cell permeability differ, with the latter potentially acting directly on cytoskeletal organization.