Abstract
Background: We have demonstrated that valproic acid (VPA), a histone deacetylase inhibitor (HDACI), can improve animal survival after hemorrhagic shock, and protect neurons from hypoxia-induced apoptosis. This study investigated whether VPA treatment works through the c-Jun N-terminal kinase (JNK)/Caspase-3 survival pathways. Methods: Wistar-Kyoto rats underwent hemorrhagic shock (60% blood loss over 60 min) followed by post-shock treatment with VPA (300 mg/kg), without any additional resuscitation fluids. The experimental groups were: (1) Sham (no hemorrhage, no resuscitation), (2) no resuscitation (hemorrhage, no resuscitation), and (3) VPA treatment. The animals were sacrificed at 1, 6, or 24 h (n = 3/timepoint), and liver tissue was harvested. Cytosolic and nuclear proteins were isolated and analyzed for acetylated histone-H3 at lysine-9 (Ac-H3K9), total and phosphorylated JNK, and activated caspase-3 by Western blot. Results: Hemorrhaged animals were in severe shock, with mean arterial pressures of 25-30 mmHg and lactic acid 7-9 mg/dL. As expected, only the VPA treated animals survived to the 6- and 24-h timepoints; none of the non-resuscitated animals survived to these time points. Treatment of hemorrhaged animals with VPA induced acetylation of histone H3K9, which peaked at 1 h and returned back to normal by 24 h. Hemorrhage induced phosphorylation of JNK (active form) and increased activated caspase-3 levels, representing a commitment to subsequent cell death. Treatment with VPA decreased the phospho-JNK (P = 0.06) expression at 24 h, without changing the total levels of JNK (P = 0.89), and this correlated with attenuation of activated caspase-3 at 24 h (P = 0.04), compared with the non-resuscitated animals. Conclusion: Treatment with HDACI, induces acetylation of histone H3K9, and reduces JNK phosphorylation and subsequent caspase-3 activation. This discovery establishes for the first time that HDACI may protect cells after severe hemorrhage through modulation of the JNK/caspase-3 apoptotic pathway.
Original language | English (US) |
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Pages (from-to) | 290-296 |
Number of pages | 7 |
Journal | Journal of Surgical Research |
Volume | 156 |
Issue number | 2 |
DOIs | |
State | Published - Oct 2009 |
Externally published | Yes |
Funding
The authors acknowledge funding for this study by a grant from the Defense Advanced Research Project Agency (DARPA) to HBA. EAS was supported by a NRSA postdoctoral fellowship (F32 GM79880) at NIH/NIGMS, and the Scholars in Clinical Science Program at the Harvard Medical School. Additional funds were provided through a generous donation by the Polsky family.
Keywords
- acetylation
- hemorrhage
- liver
- resuscitation
- shock
- valproic acid
ASJC Scopus subject areas
- Surgery