Abstract TP315: The Role of Sirt1 in Nuclear Cytoplasmic Translocation After Ischemic Stroke

Abstract

Background and rationale: Sirtuin 1, NAD-dependent deacetylase sirtuin-1 (Sirt1), plays a role in the regulation of mammalian metabolism that regulates transcription of factors, modulates the chromatin, and improves motor function. Here, we investigated rapid nuclear-cytoplasmic translocation of Sirt1 in ischemic stroke both neuron-specific Sirt1 knock-in (nSirt1 KI) and wild-type mice and demonstrated that Sirt1-specific inhibition by sirtinol affected the cGK1/2 signaling pathway within 6 h reperfusion an ischemia-reperfusion injury model. Methods: Both nSirt1 KI and WT mice were subjected to 1 h of ischemia, followed by 6 h of reperfusion. All mice measured rCBF by Laser Doppler. Sirtinol (10 mg/kg) was injected intraperitoneally as a single dose on 1 day. To assess the Sirt1, cGK1, and cGK2 protein expression, brain sample specimens were divided into the cerebral cortex, hippocampus, and striatum, and then protein expressions from brain lysates were studied by western blotting. Results: The conditions described above, i) The result of cerebral cortex obtained from total protein lysate was degraded the fastest by I/R injury, but no significant difference was found in Sirt1 and cGK1/2. ii) neuronal lysate from the hippocampus confirmed the degradation of Sirt1, cGK1, and cGK2. iii) On the TTC staining, within 6 h of reperfusion, the striatum does not appear to be damaged by sirtinol treatment, but it was confirmed that rapid Sirt1 translocation occurred on the intracellular mechanism. It was also demonstrated that subphase cGK1 and cGK2 were reduced in the striatum. Conclusion: These results confirm that Sirt1 inhibition by sirtinol treatment is involved in nuclear-cytoplasmic translocation in the striatum with an inhibitory mechanism of Sirt1. In addition, cGK1/2 is inhibited by sirtinol in the striatum, suggesting that cGK1/2 is also involved in inhibitors and that cGK1/2 responds as a subphase of Sirt1. These processes are expected to lead to toxic protein aggregates, inefficient transcription, and defective nuclear-cytoplasmic translocation via nuclear pore complex damage.