ABSTRACT
High levels of glucose (HG) induce reactive oxygen species-mediated oxidative stress in endothelial cells (ECs), which leads to endothelial dysfunction and tissue damage. However, the molecular mechanisms involved in HG-induced endothelial oxidative stress and damage remain elusive. Here we show that cellular ATP level-modulated p53 Thr55 phosphorylation plays a critical role in the process. Upon HG exposure, the elevated ATP levels induced the kinase activity of TAF1 (TBP-associated factor 1), which leads to p53 Thr55 phosphorylation. The phosphorylation dissociates p53 from the glutathione peroxidase 1 (GPX1) promoter and results in reduction of GPX1 expression. Inhibition of TAF1-mediated p53 Thr55 phosphorylation abolished those events, supporting the role of TAF1 in sensing cellular ATP elevation and in regulating GPX1 expression under the HG condition. Importantly, treating cells with HG increased intracellular H2O2 and cell apoptosis, as well as suppressed nitric oxide (NO) bioavailability and tube network formation. These effects were also remarkably reversed by inhibition of TAF1 and p53 Thr55 phosphorylation. We conclude that HG leads to endothelial dysfunction via TAF1-mediated p53 Thr55 phosphorylation and subsequent GPX1 inactivation. Our study thus revealed a novel mechanism by which HG induces endothelial oxidative stress and damage and possibly provided an avenue for targeted therapy for diabetes-associated cardiovascular diseases.
Subject(s)
Antioxidants/metabolism , Glucose/pharmacology , Human Umbilical Vein Endothelial Cells/metabolism , Tumor Suppressor Protein p53/metabolism , Adenosine Triphosphate/genetics , Adenosine Triphosphate/metabolism , Cardiovascular Diseases/genetics , Cardiovascular Diseases/metabolism , Cardiovascular Diseases/pathology , Diabetes Complications/metabolism , Diabetes Complications/pathology , Glutathione Peroxidase/genetics , Glutathione Peroxidase/metabolism , Histone Acetyltransferases/genetics , Histone Acetyltransferases/metabolism , Human Umbilical Vein Endothelial Cells/pathology , Humans , Hydrogen Peroxide/pharmacology , Nitric Oxide/metabolism , Phosphorylation/drug effects , Phosphorylation/genetics , TATA-Binding Protein Associated Factors/genetics , TATA-Binding Protein Associated Factors/metabolism , Transcription Factor TFIID/genetics , Transcription Factor TFIID/metabolism , Tumor Suppressor Protein p53/genetics , Glutathione Peroxidase GPX1ABSTRACT
While p53 activation has long been studied, the mechanisms by which its targets genes are restored to their preactivation state are less clear. We report here that TAF1 phosphorylates p53 at Thr55, leading to dissociation of p53 from the p21 promoter and inactivation of transcription late in the DNA damage response. We further show that cellular ATP level might act as a molecular switch for Thr55 phosphorylation on the p21 promoter, indicating that TAF1 is a cellular ATP sensor. Upon DNA damage, cells undergo PARP-1-dependent ATP depletion, which is correlated with reduced TAF1 kinase activity and Thr55 phosphorylation, resulting in p21 activation. As cellular ATP levels recover, TAF1 is able to phosphorylate p53 on Thr55, which leads to dissociation of p53 from the p21 promoter. ChIP-sequencing analysis reveals p53 dissociates from promoters genome wide as cells recover from DNA damage, suggesting the general nature of this mechanism.
