A novel intrinsic pro-survival mechanism against ischemic brain injury in clinically relevant animal models

Summary This exploratory proposal is motivated by the recent discovery of neuronal “actinification,” a pro-survival reorganization of the neuronal actin cytoskeleton that is observed following neuronal ischemia in vitro and in vivo. The formin protein INF2 (inverted formin 2) is the key driver of actinification. Silencing INF2 in cultured neurons prevented actinification and increased neuronal death, while augmenting INF2 increased actinification and reduced neuronal death. In a mouse model of small vessel ischemia, blocking formin activation exacerbated stroke-induced neuronal cell death. However, the in vivo effects of augmenting INF2 were not tested, due to technical limitations. The proposed project will overcome this challenge and build on the prior work to characterize actinification in vivo using middle cerebral artery occlusion (MCAO) in mouse brain, a model of large vessel occlusion that more closely represents clinically relevant stroke conditions. The central premise is that INF2-dependent actin reorganization confers a temporary pro-survival advantage to neurons undergoing ischemic stress by protecting the somatodendritic compartment from acute damage. The project will characterize actinification in vivo using this model in young and aged adult mice (Aim 1), and will directly test the hypothesis that gain of function of INF2 via overexpression of the INF2 gene will protect neurons from ischemic brain injury (Aim 2).