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Proteins of up to 230 kilodaltons are taken up by chinese hamster ovary fibroblasts exposed to electroporation under conditions generally similar to those used to mediate DNA transfection. The uptake of catalase, ovalbumin, and histone H1 labelled with fluorescein was visualized by fluorescence microscopy. Under the same conditions, the uptake of colloidal gold particles (20 nm diameter) was visualized by electron microscopy. In optimum conditions, about 25% of the cells remained viable and grew normally and about 25% of these retained labelled proteins during two cycles of further growth. About 6 x 10(4) molecules of catalase were retained per cell. Proteins were taken up when presented to the cells up to 4 h after electroporation, suggesting that mechanisms other than classical electropore formation may operate in these conditions. The proteins were localized in the cytoplasm in a predominantly vesicular pattern and histone H1 entered the nucleus in some cells.

Background:The role of uncoupling proteins (UCP) in the brain is unclear. Results: UCPs, present in astrocytes, mediate the intramitochondrial acidification leading to a decrease in mitochondrial ATP production. Conclusion: Astrocyte pH regulation promotes ATP synthesis by glycolysis whose final product, lactate, increases neuronal survival. Significance: We describe a new role for a brain uncoupling protein.