Abstract
BackgroundTaurine is a free amino acid present in high concentrations in a variety of organs of mammalians. As an antioxidant, taurine has been found to protect cells against oxidative stress, but the underlying mechanism is still unclear.MethodsIn this report, we present evidence to support the conclusion that taurine exerts a protective function against endoplasmic reticulum (ER) stress induced by H2O2 in PC 12 cells. Oxidative stress was introduced by exposure of PC 12 cells to 250 uM H2O2 for 4 hours.ResultsIt was found that the cell viability of PC 12 cells decreased with an increase of H2O2 concentration ranging from approximately 76% cell viability at 100 uM H2O2 down to 18% at 500 uM H2O2. At 250 uM H2O2, cell viability was restored to 80% by taurine at 25 mM. Furthermore, H2O2 treatment also caused a marked reduction in the expression of Bcl-2 while no significant change of Bax was observed. Treatment with taurine restored the reduced expression of Bcl-2 close to the control level without any obvious effect on Bax. Furthermore, taurine was also found to suppress up-regulation of GRP78, GADD153/CHOP and Bim induced by H2O2, suggesting that taurine may also exert a protective function against oxidative stress by reducing the ER stress.ConclusionIn summary, taurine was shown to protect PC12 cells against oxidative stress induced by H2O2. ER stress was induced by oxidative stress and can be suppressed by taurine.
Highlights
Taurine is a free amino acid present in high concentrations in a variety of organs of mammalians
Dose dependent toxicity of H2O2 in PC12 cells The PC12 cells were exposed to different concentrations of H2O2 in a range of 100-500 uM for 4 hours, the Adenosine 5’-triphosphate (ATP) assay was performed
Taurine protected PC12 cells against H2O2 induced oxidative stress In our previous paper, it was revealed that preincubation with 25 mM taurine resulted in maximal recovery from neuronal injury induced by glutamate [5]
Summary
Taurine is a free amino acid present in high concentrations in a variety of organs of mammalians. The predominant signaling pathways associated with ER stress are initiated by the ER membrane-associated proteins, protein kinase R [PKR]-like ER kinase (PERK), inositol requiring enzyme 1 (IRE1), and activating transcription factor 6 (ATF6), which in turn activate distinct signaling cascades mediating the ER stress response [15,16,17] Among these three major UPR signal transduction pathways, the IRE-1 and ATF-6 pathways increase the expression of the ER-resident chaperone, glucose-regulated protein 78 (GRP78) [18,19], and all of these three pathways up-regulate the transcription factor C/EBP homologous protein (CHOP), known as growth arrest and DNA damage-inducible gene 153 (GADD153) [20]. We demonstrated that taurine exerts a protective function against ER stress induced by oxidative stress in PC 12 cells
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