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The complex morphology of reactive astrocytes controlled by fibroblast growth factor signaling

Authors

  • Kyungjoon Kang,

    1. School of Life Sciences, Bioimaging Research Center and Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju, Republic of Korea
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  • Sung-Woong Lee,

    1. School of Life Sciences, Bioimaging Research Center and Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju, Republic of Korea
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  • Jeong Eun Han,

    1. Department of Pharmacology, College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon, Republic of Korea
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  • Ji Woong Choi,

    1. Department of Pharmacology, College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon, Republic of Korea
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  • Mi-Ryoung Song

    Corresponding author
    1. School of Life Sciences, Bioimaging Research Center and Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju, Republic of Korea
    • Address correspondence to Mi-Ryoung Song, School of Life Sciences, Bioimaging Research Center and Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea. E-mail: msong@gist.ac.kr or Ji Woong Choi, Department of Pharmacology, College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon 406-799, Republic of Korea. E-mail: pharmchoi@gachon.ac.kr

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Abstract

Astrocytes are the most abundant cell-type of the human brain and play a variety of roles in brain homeostasis and synaptic maturation, under normal conditions. However, astrocytes undergo dramatic pathological changes in response to brain injury, such as reactive gliosis and glial scar formation. Although abnormal hypertrophy and massive proliferation of astrocytes are obvious, the molecular identity and cues that dictate the structural changes in reactive astrocytes remain unclear. This study proposes that fibroblast growth factor (FGF) signaling is responsible for making astrocyte morphology more complex and hypertrophic in response to an inflammatory stimulus such as lipopolysaccharide. Primary astrocytes isolated from perinatal brains developed more branches in the presence of FGF8 or lesser branches in the presence of FGF2. Introduction of the constitutively active form of the FGF receptor 3 (caFGFR3) into the brain increases the structural complexity, with greater glial fibrillary acidic protein level in astrocytes, while overexpression of a dominant-negative form of FGFR3 (dnFGFR3) reduces it. Treatment of FGF8 facilitated the wound-healing process of primary astrocytes in vitro by changing their morphology, indicating that the FGF signal may control the responsiveness of astrocytes in injury conditions. Finally, the blockade of FGF signaling by introducing dnFGFR3 at the site of reactive gliosis reduces astrocyte branch formation and minimizes hypertrophic responses during reactive gliosis. Taken together, these results indicate that FGF8–FGFR3 signaling controls structural changes in astrocytes during reactive gliosis, under pathogenic conditions. GLIA 2014;62:1328–1344

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