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Proc Natl Acad Sci U S A. 2013 Jul 9;110(28):11612-7. doi: 10.1073/pnas.1300378110. Epub 2013 Jun 24.

Calcium-dependent N-cadherin up-regulation mediates reactive astrogliosis and neuroprotection after brain injury.

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1
Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.

Abstract

Brain injury induces phenotypic changes in astrocytes, known as reactive astrogliosis, which may influence neuronal survival. Here we show that brain injury induces inositol 1,4,5-trisphosphate (IP3)-dependent Ca(2+) signaling in astrocytes, and that the Ca(2+) signaling is required for astrogliosis. We found that type 2 IP3 receptor knockout (IP3R2KO) mice deficient in astrocytic Ca(2+) signaling have impaired reactive astrogliosis and increased injury-associated neuronal death. We identified N-cadherin and pumilio 2 (Pum2) as downstream signaling molecules, and found that brain injury induces up-regulation of N-cadherin around the injured site. This effect is mediated by Ca(2+)-dependent down-regulation of Pum2, which in turn attenuates Pum2-dependent translational repression of N-cadherin. Furthermore, we show that astrocyte-specific knockout of N-cadherin results in impairment of astrogliosis and neuroprotection. Thus, astrocytic Ca(2+) signaling and the downstream function of N-cadherin play indispensable roles in the cellular responses to brain injury. These findings define a previously unreported signaling axis required for reactive astrogliosis and neuroprotection following brain injury.

KEYWORDS:

calcium signal; reactive astrocyte; stab wound; translational repressor

PMID:
23798419
PMCID:
PMC3710861
DOI:
10.1073/pnas.1300378110
[Indexed for MEDLINE]
Free PMC Article
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