The MDM2-p53 pathway is involved in preconditioning-induced neuronal tolerance to ischemia

Rebeca Vecino,Maria Delgado-Esteban,Angeles Almeida,Juan B Salom,Jesus Agulla,Maria C Burguete,Verónica Bobo-Jiménez,Teresa Jover-Mengual

doi:10.1038/s41598-018-19921-x

Abstract

Brain preconditioning (PC) refers to a state of transient tolerance against a lethal insult that can be evoked by a prior mild event. It is thought that PC may induce different pathways responsible for neuroprotection, which may involve the attenuation of cell damage pathways, including the apoptotic cell death. In this context, p53 is a stress sensor that accumulates during brain ischemia leading to neuronal death. The murine double minute 2 gene (MDM2), a p53-specific E3 ubiquitin ligase, is the main cellular antagonist of p53, mediating its degradation by the proteasome. Here, we study the role of MDM2-p53 pathway on PC-induced neuroprotection both in cultured neurons (in vitro) and rat brain (in vivo). Our results show that PC increased neuronal MDM2 protein levels, which prevented ischemia-induced p53 stabilization and neuronal death. Indeed, PC attenuated ischemia-induced activation of the p53/PUMA/caspase-3 signaling pathway. Pharmacological inhibition of MDM2-p53 interaction in neurons abrogated PC-induced neuroprotection against ischemia. Finally, the relevance of the MDM2-p53 pathway was confirmed in rat brain using a PC model in vivo. These findings demonstrate the key role of the MDM2-p53 pathway in PC-induced neuroprotection against a subsequent ischemic insult and poses MDM2 as an essential target in ischemic tolerance.

Highlights

Ischemic tolerance (IT) is a well-known phenomenon in which brief non-injurious preconditioning stimulus confer robust neuroprotection against a subsequent severe ischemic damage[1,2,3,4,5,6,7,8]
NMDA-PC prevented neurite degeneration (Fig. 1c,e), the activation of caspase-3 induced by oxygen and glucose deprivation (OGD), as revealed by both fluorimetry assay (Fig. 1d) and immunostaning (Fig. 1e) and neuronal necrosis and cell damage at 4 hours after OGD, which were measured by trypan blue staining and lactate dehydrogenase (LDH) release (Fig. S4c), respectively
(Fig. 5a,b) and immunofluorescence (Fig. 5c). All these results indicates that NMDA-PC increases murine double minute 2 (MDM2) protein level expression, which promotes its interaction with p53 prior OGD, leading p53 nuclear and cytosolic destabilization and preventing OGD-induced p53-mediated neuronal apoptotic death

Summary

Introduction

Ischemic tolerance (IT) is a well-known phenomenon in which brief non-injurious preconditioning stimulus (preconditioning, PC; i.e exposure to low doses of N-methyl-D-aspartate, NMDA-PC) confer robust neuroprotection against a subsequent severe ischemic damage[1,2,3,4,5,6,7,8]. The protein p53 is a stress sensor that accumulates during brain ischemia leading to neuronal death. Several evidences from both animal and human studies demonstrated that cerebral ischemia initiates a cascade of metabolic events that involve the stabilization and activation of p5312–16. MDM2 and p53 form an auto-regulatory feedback loop which acts as a repressor of p53 activity in the cell[24,27,30] Under this loop, p53 stimulates the expression of MDM2, which, in turn, promotes p53 degradation[27,31]. PC attenuated ischemia-induced activation of the p53/PUMA/caspase-3 signaling pathway and promoted neuronal survival against a subsequent ischemic damage. Our findings demonstrate the key role of the MDM2-p53 signaling pathway in neuroprotection induced by PC against a subsequent ischemic insult and poses MDM2 as an essential target in IT

Methods

Results

Conclusion