Acetylation of the Pro-Apoptotic Factor, p53 in the Hippocampus following Cerebral Ischemia and Modulation by EstrogenReport as inadecuate

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Recent studies demonstrate that acetylation of the transcription factor, p53 on lysine373 leads to its enhanced stabilization-activity and increased susceptibility of cells to stress. However, it is not known whether acetylation of p53 is altered in the hippocampus following global cerebral ischemia GCI or is regulated by the hormone, 17β-estradiol 17β−E2, and thus, this study examined these issues.

Methodology-Principal Findings

The study revealed that Acetyl p53-Lysine373 levels were markedly increased in the hippocampal CA1 region after GCI at 3 h, 6 h and 24 h after reperfusion, an effect strongly attenuated by 17β−E2. 17β−E2 also enhanced interaction of p53 with the ubiquitin ligase, Mdm2, increased ubiquitination of p53, and induced its down-regulation, as well as attenuated elevation of the p53 transcriptional target, Puma. We also observed enhanced acetylation of p53 at a different lysine Lys382 at 3 h after reperfusion, and 17β−E2 also markedly attenuated this effect. Furthermore, administration of an inhibitor of CBP-p300 acetyltransferase, which acetylates p53, was strongly neuroprotective of the CA1 region following GCI. In long-term estrogen deprived LTED animals, the ability of 17β−E2 to attenuate p53 acetylation was lost, and intriguingly, Acetyl p53-Lysine373 levels were markedly elevated in sham non-ischemic LTED animals. Finally, intracerebroventricular injections of Gp91ds-Tat, a specific NADPH oxidase NOX2 inhibitor, but not the scrambled tat peptide control Sc-Tat, attenuated acetylation of p53 and reduced levels of Puma following GCI.


The studies demonstrate that p53 undergoes enhanced acetylation in the hippocampal CA1 region following global cerebral ischemia, and that the neuroprotective agent, 17β−E2, markedly attenuates the ischemia-induced p53 acetylation. Furthermore, following LTED, the suppressive effect of 17β−E2 on p53 acetylation is lost, and p53 acetylation increases in the hippocampus, which may explain previous reports of increased sensitivity of the hippocampus to ischemic stress following LTED.

Author: Limor Raz , Quan-guang Zhang , Dong Han, Yan Dong, Liesl De Sevilla, Darrell W. Brann



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