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IRES-mediated Wnt2 translation in apoptotic neurons triggers astrocyte dedifferentiation. 2022

Hong Fan, and Jialei Yang, and Kun Zhang, and Junling Xing, and Baolin Guo, and Honghui Mao, and Wenting Wang, and Yingzhou Hu, and Wei Lin, and Ying Huang, and Jian Ding, and Caiyong Yu, and Fanfan Fu, and Li Sun, and Jing Wu, and Youyi Zhao, and Wenbin Deng, and Chengji Zhou, and Mengsheng Qiu, and Shengxi Wu, and Yu-Qiang Ding, and Yazhou Wang

Department of Neurobiology and Institute of Neurosciences, School of Basic Medicine, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an, Shaanxi, 710032, China.

Reactive astrogliosis usually bears some properties of neural progenitors. How injury triggers astrocyte dedifferentiation remains largely unclear. Here, we report that ischemia induces rapid up-regulation of Wnt2 protein in apoptotic neurons and activation of canonical Wnt signaling in reactive astrocytes in mice, primates and human. Local delivery of Wnt2 shRNA abolished the dedifferentiation of astrocytes while over-expressing Wnt2 promoted progenitor marker expression and neurogenesis. Both the activation of Wnt signaling and dedifferentiation of astrocytes was compromised in ischemic caspase-3-/- cortex. Over-expressing stabilized β-catenin not only facilitated neurogenesis but also promoted functional recovery in ischemic caspase-3-/- mice. Further analysis showed that apoptotic neurons up-regulated Wnt2 protein via internal ribosome entry site (IRES)-mediated translation. Knocking down death associated protein 5 (DAP5), a key protein in IRES-mediated protein translation, significantly diminished Wnt activation and astrocyte dedifferentiation. Our data demonstrated an apoptosis-initiated Wnt-activating mechanism which triggers astrocytic dedifferentiation and facilitates neuronal regeneration.