Cofilin Inhibition by Limk1 Reduces Rod Formation and Cell Apoptosis after Ischemic Stroke

• Published in: Neuroscience 2020-09, Vol.444, p.64-75
• Main Authors: Chen, Bin, Lin, Wanqing, Qi, Wan, Li, Shibin, Hong, Zhenfeng, Zhao, Hongjia
• Format: Article
• Language: English
• Subjects: Actin Depolymerizing Factors; Animals; Apoptosis; Brain Ischemia; cofilin rod; Infarction, Middle Cerebral Artery; Ischemic Stroke; Lim Kinases; Limk1; Rats; Stroke; tMCAO
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2020.07.019

•ATP depletion induced cofilin rod formation and neuronal apoptosis.•Infarct volume increased from 2 h to 24 h, then became stable from 24 h to 7 d after tMCAO.•Rod formation and cell apoptosis was gradually induced in the ischemic penumbra and core areas of tMCAO rats.•Inhibition of cofilin by Limk1 reduced rod formation and cofilin mediated-apoptosis at 24 h after tMCAO. Cofilin, a cytoskeletal actin severing protein, is essential for the initiation phase of apoptosis. The formation of cofilin rods (containing 1:1 cofilin:actin) has been studied in cultured mammalian neurons under conditions of excessive glutamate, ATP depletion (ATP-D) or oxidative stress. These conditions simulate the pathologies occurring during ischemic stroke. In this study, we investigated the potential involvement of cofilin during ischemic-stroke induced apoptosis. Transient middle cerebral artery occlusion (tMCAO) was performed to establish an experimental model of ischemic stroke. We used 2,3,5-Triphenyltetrazolium Chloride (TTC) and immunostaining of the neuronal marker neuronal nuclei (NeuN) to evaluate the evolving phases of infarction in rats subjected tMCAO. Immunostaining and TdT-mediated dUTP Nick-End Labeling (TUNEL) apoptosis staining were collaboratively used to examine cofilin rod formation and cell apoptosis in response to ischemia at different time points (2 h, 8 h, 24 h and 7 d). Our results showed that infarct volume increased initially, between the first 2 h to 24 h and became stabilized 24 h to 7 d after tMCAO. The formation of cofilin rods significantly increased in the cortical core (from 2 h) and penumbra (from 8 h), peaking at 24 h and gradually diminishing 7 d after tMCAO. Progressive accumulation of cofilin rods subsequently induced microtubule-associated protein-2 (MAP2) degradation and ischemic cell apoptosis in the infarct cortex after stroke. To further corroborate the role of activated cofilin in ischemic stroke, inhibition of cofilin by LIM kinase (Limk1) over-expression was performed. Lmik1 reduced cofilin rod formation and MAP2 degradation, and consequently, attenuated cofilin mediated-apoptosis 24 h after tMCAO. From this evidence we conclude that cofilin plays a role in the onset of ischemic-induced apoptosis and may be efficacious in future studies as a drug target for ischemic stroke.