Role of intracellular labile iron, ferritin, and antioxidant defence in resistance of chronically adapted Jurkat T cells to hydrogen peroxide

Abstract

To examine the role of intracellular labile iron pool (LIP), ferritin (Ft), and antioxidant defence in cellular resistance to oxidative stress on chronic adaptation, a new H2O2-resistant Jurkat T cell line “HJ16” was developed by gradual adaptation of parental “J16” cells to high concentrations of H2O2. Compared to J16 cells, HJ16 cells exhibited much higher resistance to H2O2-induced oxidative damage and necrotic cell death (up to 3 mM) and had enhanced antioxidant defence in the form of significantly higher intracellular glutathione and mitochondrial ferritin (FtMt) levels as well as higher glutathione-peroxidase (GPx) activity. In contrast, the level of the Ft H-subunit (FtH) in the H2O2-adapted cell line was found to be 7-fold lower than in the parental J16 cell line. While H2O2 concentrations higher than 0.1 mM fully depleted the glutathione content of J16 cells, in HJ16 cells the same treatments decreased the cellular glutathione content to only half of the original value. In HJ16 cells, H2O2 concentrations higher than 0.1 mM increased the level of FtMt up to 4-fold of their control values but had no effect on the FtMt levels in J16 cells. Furthermore, while the basal cytosolic level of LIP was similar in both cell lines, H2O2 treatment substantially increased the cytosolic LIP levels in J16 but not in HJ16 cells. H2O2 treatment also substantially decreased the FtH levels in J16 cells (up to 70% of the control value). In contrast in HJ16 cells, FtH levels were not affected by H2O2 treatment. These results indicate that chronic adaptation of J16 cells to high concentrations of H2O2 has provoked a series of novel and specific cellular adaptive responses that contribute to higher resistance of HJ16 cells to oxidative damage and cell death. These include increased cellular antioxidant defence in the form of higher glutathione and FtMt levels, higher GPx activity, and lower FtH levels. Further adaptive responses include the significantly reduced cellular response to oxidant-mediated glutathione depletion, FtH modulation, and labile iron release and a significant increase in FtMt levels following H2O2 treatment.

Deferoxamine attenuates lipopolysaccharide-induced inflammatory responses and protects against endotoxic shock in mice

“…The intracellular level of iron is tightly controlled through regulation of the cellular uptake of iron and the sequestering of low molecular labile iron by iron chelators. An excess of free iron also donates electrons for the generation of superoxide radicals (known as ROS) and can participate in the regulation of hydroxyl radicals via the Fenton reaction [3]. ROS facilitates LPS-induced inflammatory processes, eventually leading to tissue damage and organ failure.…”

The effect of anti-inflammatory properties of ferritin light chain on lipopolysaccharide-induced inflammatory response in murine macrophages

“…Interestingly, FTL seems to be more sensitive to oxidation [39]. The FTL content is decreased due to the oxidation of intracellular ferritin, and the consequent proteasomal degradation reduced the ferritin content [17,[39][40][41][42]. The experiment with the proteasomal inhibitor MG-132 (presented in supplementary Fig.…”

“…1) provided evidence that the proteasome is instrumental in the turnover of FTL. As a consequence of FTL degradation, an expansion of the free iron pool is likely to occur [42,43]. Iron plays a critical role during this process because it catalyzes the generation of free radicals formed from hydrogen peroxide via the Fenton reaction.…”

“…Basal ROS production is boosted by expansive iron released from ferritin and accelerates ferritin degradation [39,43]. At the same time, the increased availability of iron induces ferritin gene transcription [42,43]. The specific iron chelator SIH inhibited LPS-induced protein expression of FTL (supplementary Fig.…”

The effect of alpha lipoic acid on hydrogen peroxide-induced lipid peroxidation in rat liver homogenates

“…Literatürde in vitro çalışmalardan indüksiyon ortamı olarak homojenat kullananlarda 10 mM, 5 mM [14,15] hücre kültürü kullananlarda ise 3 mM, 500 μM, 200 μM H 2 O 2 [16][17][18] konsantrasyonları ile oksidatif stresin indüklendi-ği görülmektedir Homogenatlarda oksidatif stres indük-lenmese bile otooksidasyon oluşmaktadır [19]. Oksidatif stresin indüklendiğini söyleyebilmek için otooksidasyona bırakılan gruptan anlamlı olarak daha yüksek lipid peroksidasyon oluşturulması gerekmektedir.…”