Slow rise of Ca2+ and slow release of reactive oxygen species are two cross-talked events important in tumour necrosis factor-alpha-mediated apoptosis
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AbstractTumour necrosis factor-alpha (TNF-alpha) was found to be a cell cycle-independent apoptogenic cytokine in cultured fibroblast L929 cells. This assertion is based on the observations (1) TNF-alpha increased the number of cells with hypo-diploid DNA in a time dependent manner as revealed by flow cytometry, and (2) TNF-alpha induced DNA fragmentation as resolved by agarose gel electrophoresis. When cells were exposed to TNF-alpha (50 ng/ml), a slow rise in intracellular free Ca2+ level and a delayed increase in the production of reactive oxygen species (ROS) (both observed 3 h after the addition of TNF-alpha) were observed in fluo-3 and fura-red or dichlorofluorescein loaded cells, respectively. Interestingly, challenge of cells with TNF-alpha in the presence of BAPTA/AM, an intracellular Ca2+ chelator, decreased the release of ROS. Removal of ROS by 4-hydroxy 2,2,6,6-tetra-methyl-piperidinooxy (4OH-TEMPO) blocked the TNF-alpha-mediated Ca2+ rise. Moreover, when cells were exposed to TNF-alpha. with both COH-TEMPO and BAPTA/AM, more viable cells were found than from treatment with either BAPTA/AM or 4OH-TEMPO. These results suggest that ROS and cellular Ca2+ are two cross-talk messengers important in TNF-alpha-mediated apoptosis.
All Author(s) ListKo S, Kwok TT, Fung KP, Choy YM, Lee CY, Kong SK
Journal nameFree Radical Research
Volume Number33
Issue Number3
Pages295 - 304
LanguagesEnglish-United Kingdom
Keywordsapoptosis; Ca2+; cross talk; L929 cells; ROS; TNF-alpha
Web of Science Subject CategoriesBiochemistry & Molecular Biology; BIOCHEMISTRY & MOLECULAR BIOLOGY

Last updated on 2020-02-07 at 05:01