High glucose induces mitochondrial p53 phosphorylation by p38 MAPK in pancreatic RINm5F cells

Abstract

Pancreatic β-cell death in type 2 diabetes has been related to p53 subcellular localisation and phosphorylation. However, the mechanisms by which p53 is phosphorylated and its activation in response to oxidative stress remain poorly understood. Therefore, the aim of this study was to investigate mitochondrial p53 phosphorylation, its subcellular localisation and its relationship with apoptotic induction in RINm5F cells cultured under high glucose conditions. Our results show that p53 phosphorylation in the mitochondrial fraction was greater at ser392 than at ser15. This increased phosphorylation correlated with an increase in reactive oxygen species, a decrease in the Bcl-2/Bax ratio, a release of cytochrome c and an increase in the rate of apoptosis. We also observed a decline in ERK 1/2 phosphorylation over time, which is an indicator of cell proliferation. To identify the kinase responsible for phosphorylating p53, p38 mitogen-activated protein kinase (MAPK) activation was analysed. We found that high glucose induced an increase in p38 MAPK phosphorylation in the mitochondria after 24-72 h. Moreover, the phosphorylation of p53 (ser392) by p38 MAPK in mitochondria was confirmed by colocalisation studies with confocal microscopy. The addition of a specific p38 MAPK inhibitor (SB203580) to the culture medium during high glucose treatment blocked p53 mobilisation to the mitochondria and phosphorylation; thus, the release of cytochrome c and the apoptosis rate in RINm5F cells decreased. These results suggest that mitochondrial p53 phosphorylation by p38 MAPK plays an important role in RINm5F cell death under high glucose conditions.

Effect of Crocin and Voluntary Exercise on P53 Protein in Pancreas of Type2 Diabetic Rats

“…Hyperglycemia promotes p53 phosphorylation which correlates with activation of pro-apoptotic proteins such as Bax. 29 Furthermore, Hinault et al (2011) demonstrated that in p53 knockout mice, the β-cell population regenerate and rescue the diabetic phenotype in this animal model. 30 According to above mention statements, it can be stated that up regulation of the apoptosis pathways are implicated in the development of type 2 diabetes.…”

Effect of High Glucose-Induced Oxidative Stress on Paraoxonase 2 Expression and Activity in Caco-2 Cells

“…Post-translational modifications of p53, including phosphorylation, are common ways to activate p53 in response to DNA damage and perturbation of phospholipid homeostasis [57]. The increased phosphorylation of p53 correlates with an increase in reactive oxygen species, a release of cytochrome c, and an increase in the rate of apoptosis [58]. Therefore, we hypothesize that the significant increase of Pp53/p53 ratio in Caco-2 cells incubated with high glucose is related to glyco-oxidative stress and contributes to apoptosis pathways.…”

Zerumbone protects INS-1 rat pancreatic beta cells from high glucose-induced apoptosis through generation of reactive oxygen species

“…Activation of MAPK pathways may lead to either cell survival or apoptosis depending on cellular contexts and stimuli [29]. It has been reported that high glucose induces p53-dependent mitochondrial apoptosis of pancreatic RINm5F cells via activation of p38 MAPK [30]. Inhibition of p38 MAPK has been shown to prevent pancreatic b cell apoptosis after islet transplantation in a canine model [31].…”