Abstract TP32: Sirtuin 3 Regulation of Mitochondrial Dynamics and Neuronal Apoptosis During Ischemia/Reperfusion

Abstract

Ischemic stroke occurs when the blood supply to the brain is interrupted, reducing the access of affected tissue to oxygen and glucose. The lack of oxygen inhibits the electron transport chain, leading to intracellular ATP deficiency, cellular damage, and death. The restoration of blood flow, known as reperfusion, allows the reintroduction of oxygen but may cause increased oxidative stress, as it hyperactivates the electron transport chain and thus induces excessive production of reactive oxygen species (ROS), leading to further cell death. One potential therapeutic target for reperfusion injury is Sirtuin 3 (SIRT3), which mediates the deacetylation of enzymes that are responsible for the reduction of ROS, leading to protection against oxidative stress. This study aims to understand the role of SIRT3 on ischemia and reperfusion-induced neuronal apoptosis. Primary neurons were isolated from wildtype mice postnatal day 0-1 and cultured for 14 days. The neurons underwent 2-hour oxygen-glucose deprivation mimicking stroke, followed by reperfusion. The neurons were then lysed, and western blots were done to analyze changes in protein levels. The western blots show that SIRT3 levels significantly decline over 1-6 hours post-reperfusion (n≥3, p<0.05), and TOM20, a mitochondrial protein, declines at 1 hour post-reperfusion(n≥3, p<0.05), indicating mitophagy. In addition, the cleavage of caspase-3 significantly increases at 4 hours post-reperfusion (n=3, p<0.05), implying apoptosis. Our data suggests that SIRT3 plays a crucial role in the mitochondrial metabolism of neurons and could be a potential target for reperfusion therapy. Future experiments would examine the effects of a SIRT3 activator and inhibitor on cell apoptosis.