Downregulation of NAD-Dependent Deacetylase SIRT2 Protects Mouse Brain Against Ischemic Stroke

Sirtuin 2 (SIRT2) is a member of NAD⁺-dependent protein deacetylases involved in a wide range of pathophysiological processes including myocardial injury, Parkinson's disease, and Huntington's disease. However, the direct implication of SIRT2 in ischemic stroke is still unclear. In the present study, we observed that SIRT2 protein was mainly expressed in the cytoplasm of neurons, but not in astrocyte and microglia. SIRT2 was upregulated in ischemic neurons in the oxygen-glucose deprivation cell model and in the transient middle cerebral artery occlusion (tMCAo) mouse model. Moreover, expression of SIRT2 was evaluated by immunohistochemistry in human brains consisting of ischemic penumbra of cerebral stroke, and their age-matched normal controls without diagnosed neurological disorders. The results revealed that SIRT2 was mainly expressed in the cytoplasm and neurites of neurons in the brains of normal subjects, while an elevated expression and nuclear translocation of SIRT2 were detected in the ischemic penumbra of cerebral stroke. Downregulation of SIRT2 using the SIRT2-specific inhibitor AGK2 or SIRT2 knockout had neuroprotective effects in tMCAo model, which could decrease the infract volume and neurological impairment scores. In summary, our findings revealed that SIRT2 was upregulated during neuronal ischemia and translocated into neuronal nuclei, while downregulation of SIRT2 could significantly protect neurons against cerebral ischemia.